Best Single Engine Glider?

[vabsie]

Hi again chaps and ladies ...

Haven't started my PPL yet due to work commitments :( but keep myself entertained by reading this forum and aviation books in the meantime.

I love the idea of flying (As my tial lesson was great), but safety is also important to me and I can't help but to notice the number of people on this forum who experienced engine failures.

Going through some of these threads one guy called Chuck .. had about 6 or 7 instances where the engine had to be switched off and forced landings were made.

I realise that forced landings is something that should be practiced lots so that you know what to do when it happens for real and not freak out. But from reading some of these posts ..... if you fly a lot and you fly for many years it seems like there is a pretty good chance that you will experience this at some stage ... or is this not quite the case? I have to admit the thought of it is slightly off putting.

Secondly ... some of you that do these north trans atlantic flights ... is it pretty much a case of just biting the bullet and hope for the best when you're over water? Again knowing that engine failures are "fairly common" would probably make me think twice?

Then, I know that you pretty much have one chance to make a good landing in case you experience an engine failure, which brings me on to my last question: Which single engine aeroplane would be rated as having the best "gliding" potential ... would it be a little cessna 152 or rather something like a pa28? Do high wings glide better?.. or do they all pretty much come down like rocks.

Sorry if some of these questions seem daft but your comments would be great thanks!

PS - I know that there are other threads about engine failures, spinning props and how to make the best landing, hence some slightly different questions above. Thx

[shortstripper]

All aeroplanes will glide, obviously some better than others. However, engine failures are actually quite rare and when they do happen, they can usually be linked to some failure on the part of the pilot or aircraft's maintanence (usually fuel starvation or carb icing) How well the aircraft "glides" has less to do with it's ability to arrive back on terra-firma safely than it's stall speed, mass and landing distance. I believe a Boeing 747 actually has a pretty good glide angle ... but I'd not want to dead stick one if the engines failed! A typical microlight though, glides like a brick, but can be put down safely in a space not much bigger than a garden!

I've had one engine failure but just scraped into a small airfield. It was my fault as I was new to the type and ran it out of fuel even though it wasn't empty :ouch:

SS

[Genghis the Engineer]

It depends what you fly. Whilst it is best practice to assume that if you are in a single engined aeroplane, the engine will fail at some random point on the current or next flight, the reality is that the majority of modern light aircraft engines are extremely reliable and most pilots will never experience an engine failure. (I'll admit to several including a couple of field landings, but much of my flying has been with uncertified engines and a fair bit of that test flying new homebuilts).

Unless an aeroplane has good enough glide capability to thermal, then a good glide ratio will only extend your options, you'll still be coming down eventually (and that's even true in a glider, albeit possibly much later). However, if you are looking for very good glide performance from a single engined aeroplane then the best will certainly be from a motorglider such as a G109b (or a microlight/motorglider hybrid such as a Chevvron). After that, it's likely to be the modern composite aeroplanes that are best such as the Diamond DA40 or the Europa.

For water crossings "hoping for the best" is not the best approach - it's more a combination of confirming likely engine reliability, carrying appropriate safety equipment, planning a route which minimises time over water and maximises rescue opportunities. For flights over mountains, the same applies - to be honest I'd rather have an engine failure low over the English Channel than low over the middle of Snowdonia.

G

[Frelon]

Don't have any of these engine related problems with a glider! So much to go wrong in an aeroplane with an engine.........I jest really!

But if you have not started your PPL yet why not start with a few gliding lessons to get a taste for engineless flight. You might even like it, and what's more it will give you skills that can only enhance your PPL training.

Remember in a glider you only get one chance of a landing ;)

[SNS3Guppy]

Vabsie,

Welcome to the wide world of aviation.

Most light airplanes have a glide ration which approximates about a 6:1 ratio or so, though some as little as 3:1...for every foot the aircraft descends, it glides forward three to six feet. Some better, some worse, but that's about the average. That said, the distance one can glide forward isn't particularly important. What's important is being able to land once you get done with the glide.

I've experienced a number of engine failures over the years in single and multi engine aircraft. Only one has resulted in any damage, and that occured at low level in mountainous terrain in the middle of a forest fire. The damage was minor, and I was flying the same airplane a month later after thorough inspections and some light repairs. That particular airplane had a relatively inefficient glide ratio, but the distance wasn't the issue; it was the landing, which was made on rough ground on a hillside. It ended well; I walked away.

Remember that the airplane flies with or without the engine; you don't fly the engine, you fly the wing. Excess thrust, or power, determines the ability of the airplane to climb...but not to land. Only you can do that.

Your safety depends largely on how you plan and conduct your flight. Remaining over and within distance of suitable forced landing sites, for example, is an important part of operating the airplane safely; always know where you can go and have a plan to get there, no matter what the altitude.

I've spent a lot of time in single engine airplanes in places that aren't conducive to a forced landing; inside the Grand Canyon, for example, where very few long, flat spaces are available to set down in the event of an engine failure. I did nearly all my flying there in single engine piston airplanes, often down inside the canyon, often landing on dirt runways and operating in box canyons in rocky, sheer terrain.

In such cases, glide ratio and the best glider was never an issue. The ability to put the airplane down was, and it did happen from time to time to individuals who experienced mechanical failues, fuel issues, weather, conditions that no longer permitted flight (extremely strong downdrafts, etc) and so forth. I experienced one engine failure in there during my time. What I did do was ensure that while a long flat smooth surface might not be available, I could always make a controlled forced landing if the need would arise; down river, on a sandbar, in the water, into trees, etc. I used local wind currents (such as strong updrafts on the downwind side of the canyon) to my benifit and planned my flight through terrain to take advantage of both the terrain and the conditions to give me the best opportunities in the event such a situation would arise.

Most importantly one must always recognize the concept that an engine failure is never a matter of if, but when. It's a mechanical object, just like the airplane, and mechanical objects break. I never make a takeoff without planning for an engine failure. In comparison to the number of takeoffs I've made, the number of engine failures is a very small percentage...very, very small. But it does happen, it has happened, and I always plan on it, however remote the possibility may be.

A fairly recent event in the news was a 747 which experienced multiple engine failures or power loss shortly after takeoff from a mountain field at night, and executed a very dramatic, though argueably successful, forced landing off field. The aircraft was completely destroyd, except for the flight deck, in which eight crewmembers survived. The point there is that while the airplane didn't have what one might call a favorable glide ratio, and certainly isn't made for off-field forced landings, one was made...and most importantly, no matter how many engines you may have, you should always plan on losing them. It does happen.

In a light airplane, power loss isn't the end of the world. The most common engine failure isn't a complete, catastrophic failure, but a partial-power failure. This may or may not enable you to return to an airport. A failed cylinder, for example, or even a fouled spark plug, slipped magneto, etc...might cause enough shaking and vibration to require shutting the engine down, or may simply enable you to switch the good mag and return home.

Whether the engine runs or doesn't, the airplane still flies, and your only concern is maintaining enough airspeed to maintain control while switching your plans to put the airplane on the ground.

North Atlantic flights in single engine airplanes are gambles, no matter how you slide it.

[vabsie]

thanks for the replies so far ...gte

Frelon .. someone got me a red-letter day and I'm planning to maybe do a gliding lesson as part of that .... need to call and find out where close to London it can be done.

SNS3Guppy - Very informative and hellpful thanks! It makes me realise that engine failure do not necessarily go hand in hand with kicking the bucket. At the same time, still a bit of a concern that you also experienced a few .... but I appreciate it's because you fly/flew a lot. Just thought in an ideal world it would be nice to fly without all this drama :)

V

[Mark 1]

I seem to recall the average figure was about 7000 hours per power failure.

In 2000 hours' flying I've had 3 power losses in-flight resulting in 2 successful forced landings and one where power was recovered (mechanical fuel pump failure - boost pump got me home). Probably more than my fare share.

It's part of the design and certification procedure that the higher the likelihood of one of these events, the more the aircraft has to be designed to make them survivable. Principally for single engine aircraft, this means a low stall speed making field landings reasonably possible. It's also an essential part of the training in SEPs that you practise and can safely execute a controlled glide to a suitable forced landing site. Failing to fly the aeroplane and maintain a safe speed and attitude is more likely to result in disaster than hitting obstacles in the landing run. There have been several cases where aircraft have hit trees without causing serious injury because the aircraft was stabilised at a sensible approach speed.

If you look at the fatal accident summaries for SEP aircraft, forced landings don't feature that much.

[SNS3Guppy]

Vabsie,

The most dangerous component in the airplane continues to remain the pilot.

Engine failures can occur from environmental conditions (carburetor ice, for example), misfueling (contaminated fuel, water in the fuel tank, etc), mechanical problems (thrown rod, slipped magneto, failed valve...) or disruptionto airflow (blocked air filter, and so forth). Regardless of the cause, and regardless of the statistical frequency at which they may occur, one always plans for them and takes full advantage when it doesn't happen.

I once experienced a very rapid onset of carburetor ice in a straight-tail Cessna 182 in instrument conditions. The engine ran rough and as I pulled the carburetor heat on, the control broke off in my hand (the wire leading to the carb air box failed). I landed on a gravel strip in a valley after emerging from the base of the clouds. It was a high base, and the landing was uneventful. On another occasion I pushed the power up too quickly when deer ran in front of the J-3 cub I was flying, and the engine promptly quit. I was attempting to go around, but made other plans one the power was gone. That too, was uneventful. On another occasion, I experienced a rough engine and then a failure due to a fuel flow fluctuation condition in a Cessna 207. It was in rough desert mountain terrain, and I was close to the terrain. It happened to occur in an unfavorable spot. Switching tanks, applying boost, and adjusting the throttle and mixture resulted in a quick recovery and an uneventful landing at an airport not long thereafter.

On another occasion in a Cessna 206 a lot of banging and vibration occured when a magneto failed not long after departure. I prepared to land on a road, and in the process switched mags, found that it ran extremely rough on one and very well on the other, and made an uneventful landing at an airport not too far away. On another occasion with a student, the airplane began vibrating hard and shaking, I reduced power and remained over a highway while making my way to an airport. I continued to climb a little as I went, and kept suitable sites to make a forced landing beneath me. I landed at the airport without event. On another occasion with a student, following a simulated power off approach to a runway during training, the student applied power to go around and we did...for about 30 seconds...then the engine ran very rough and then quit. Timely application of carburetor heat restored power and we continued around the pattern.

You can see a pattern. How the event ends is largely under your control, and that's why you're doing your training. It's all part of the preparation to be the pilot in command of your airplane. It seems a scary thought presently, perhaps even daunting. It's not. If your instructor is worth his weight in salt, then by the time you're done, you'll be pleasantly surprised when your your engine doesn't fail, and an engine failure should be a second-nature occurence.

I was behind an Ag Truck as we prepared to go spray a field about 20 years ago. I saw a very bright fireball come out of his airplane as the exhaust blew off, a brief explosion, and he shut down. The damage was minimal, and the cause was a failed magneto. It had disintegrated, in fact. It happened on the ground as he advanced power to move onto the runway. Furtunately it happened then, but he was as fully prepared as I was to deal with it had it happened during the takeoff or any time thereafter. Just as you will be.

Bob Hoover, a well known aerobatic, test, and combat pilot, used to do an airshow routine in a shrike commander. It involved a full aerobatic demonstration on both engines. Then he would shut down one engine and perform the routine, then shut down the second engine and perform it without power. It's a matter of energy management and airmanship, and he did a superb job. The mere fact that he had no power available didn't hinder his ability to control the airplane. In fact, part of his routine was returning the airplane to it's starting point after the power off routine...still without power.

Losing your engine can and does happen, but it's not a dire emergency unless you make it so. After you've been training for a short while, you'll see why. The glide down, and the distance it consumes, is really significant only in allowing you to reach a suitable landing site. The ability to glide a long distance is meaningless and irrelevant, if you always keep an engine failure in mind, act accordingly, and keep a suitable landing site nearby. Do that, and you needn't fear.

There are few things more pleasurable than flight in a light single engine airplane. Enjoy every moment of it. Should the occasion arise when you have an opportunity to to exercise some of the abnormal or "emergency" skills you'll learn, be grateful for the experience and savor it. Such occasions don't come along often, and can't be bought with money. Fly safe.

[vabsie]

Brilliant thanks again SNS3Guppy

[SNS3Guppy]

In-Flight Emergencies: Surviving Engine Failure (http://www.pilotworkshops.com/members/login.cfm?hpage=208.cfm)

[vabsie]

will check it out thanks .. in the process of registering.

[RatherBeFlying]

In gliders, engine failure is running out of lift (or failure to find and make use of same:} ) If too far away from the home field, you will be landing elsewhere. You get used to begging for lift while low within reach of a selected field, and if lucky enough to get away may repeat the situation.

A field landing in a glider with a sink rate of 200' / min is a considerably more leisurely affair than in a single engine airplane that is going down at 800' / min.

I suggest that sink rate and the ability to control it with spoilers, sideslip and flaps counts for more than raw glide ratio; however the glide ratio does give you more choice of fields.

The more difficult form of engine failure for gliders is engine failure of the towplane at low level where you have to let go of the rope and miss the towplane, but a student on first solo just managed it: Student Pilot Makes Safe Landing (http://www.news-register.net/page/content.detail/id/512611.html?nav=510) :ok:

[Katamarino]

I notice in that article that a photo of the Pawnee is shown, and described as the glider that landed in a field (I suppose at that point it technically was...)

Hurrah for journalists!

[OFBSLF]

Bob Hoover, a well known aerobatic, test, and combat pilot, used to do an airshow routine in a shrike commander. It involved a full aerobatic demonstration on both engines. Then he would shut down one engine and perform the routine, then shut down the second engine and perform it without power. It's a matter of energy management and airmanship, and he did a superb job. The mere fact that he had no power available didn't hinder his ability to control the airplane. In fact, part of his routine was returning the airplane to it's starting point after the power off routine...still without power.I had the privilege of seeing Bob Hoover's airshow routine once. Absolutely incredible.:D

[bArt2]

In the 22 years that I fly I did about 3500 flights and did not experience engine failures or other big failures.

I did encounter a few car crashes however, dangerous thing driving a car, beware.

Keeping my fingers crossed.

Bart

[Piper_Driver]

I've seen Hoover's energy management routine at least a half dozen times, and it was perfect every time. Bob was incredible!

[Lost man standing]

Most light airplanes have a glide ration which approximates about a 6:1 ratio or so, though some as little as 3:1Not true SN3.

A Cessna 152 is around 9:1, a Warrior around 11:1. The worst you are likely to get in a "proper aeroplane" (not a microlight) is better than 7:1, and in a retractable you might get twice that if you manage to stop the prop (or have managed a double failure in a twin, and feather the props).

Lift:drag ration is equal to glide ratio. If your best lift:drag ratio was 3:1 you'd never get airborne in, for example, a 1100 kg aircraft with 160 hp.

If you put the following in Google (it sorts out all the units) "160 hp / 75 kt" it tells you that the maximum thrust from perfect transmission of 160 hp at 75 kts is 3,313 N. Maximum lift would be three times this, 9,919 N. The force just to hold up a 1100 kg aircraft is 10,791 N.

[SNS3Guppy]

Climb rate is a function of excess power, whereas glide ratio is a function of lift against drag as established by angle of attack. The lift to drag ratio varies with the AoA, which generally in light airplanes we establish by establishing an airspeed...a general approximation of AoA, but not a direct indication.

The glide ratio depends, then, on the airspeed we select, as well as the way the airplane is configured, and flown. An airplane flown at 65 knots will have a different glide than an airplane with 10% flaps extended at 65 knots, and different yet from an airplane flown slightly out of rig or out of "coordination" with or without flaps, etc. Further, the glide ratio depends on the energy absorption of the propeller, and the drag thereof; an airplane with a windmilling propeller glides farther and differently than an airplane with a stopped propeller, and different yet from an airplane being operated at a "zero thrust" setting.

Additionally, the two glides may be made with respect to "best" conditions; one will be maximum range, or the farthest glide, the other with minimum sink; decreased glide ratio and distance, but also decreased rate of descent and a longer time to reach the ground...as well as a reduced vertical impact rate if the same glide speed is maintained to impact.

Lift:drag ration is equal to glide ratio. If your best lift:drag ratio was 3:1 you'd never get airborne in, for example, a 1100 kg aircraft with 160 hp.

If you put the following in Google (it sorts out all the units) "160 hp / 75 kt" it tells you that the maximum thrust from perfect transmission of 160 hp at 75 kts is 3,313 N. Maximum lift would be three times this, 9,919 N. The force just to hold up a 1100 kg aircraft is 10,791 N.


That's incorrect, both regarding lift, and regarding thrust. In particular, one cannot equate the horsepower output of the engine with thrust, especially without specific information regarding propeller (pitch, fixed, constant speed, etc), propeller efficiency, propeller slippage, atmospheric conditions, propeller RPM, torque, airspeed, and so forth. Additionally, the engine never provides "perfect transmission." Further, climb is a function of excess thrust beyond that required to sustain level flight for a given equivilent airspeed and aircraft configuration. Further still, lift is a function of configuration and angle of attack, not engine power or thrust imparted by the propeller to the airstream.

You stipulated a force (in Newtons) which presumably represents the thrust you've calculated required to sustain level flight in a light airplane. Without having addressed the aircraft type, airspeed, weight, and other pertinent conditions, you simply can't throw out a number suggesting how much power is required, because no other information is given. What you have there is wild guesswork. Lift required to sustain flight is the weight of the aircraft plus down load, in a simple model.

You've confused yourself somewhat by attempting to come up with a thrust value in the first place, further by attempting to multiply it by three to equate a theoretical glide ratio (it doesn't work that way), and by introducing thrust into a glide equation in the first place. Moreover, an aircraft which glides 3:1 at L/Dmax doesn't require three times the thrust to fly, or four times the thrust to fly. You're attempting to impose the thrust value you've arbitrarily determined against what you perceive to the the value of the drag (which isn't known, and can't be directly determined strictly based on the glide ratio)...glide ratio is not the same as L/D ratio, and varies disproportionately as L/D is varied with configuration and AoA.

But it sounds good on the surface view.

You are correct, however, in that some airplanes have higher glide ratios than others. The Katana, or some versions, have glide ratios in excess of 14:1. Sailplanes can be very high...60:1. The U-2 wrings out about 28:1. The Cessna 150 and the Concorde both shared about the same number, around 7 to 8:1.

The cessna 150 has a sea level gross power to weight ratio of 1:16...sixteen pounds per one horsepower, though this is rated power and the engine produces substantially less with an increase in altitude, as well as lower propeller efficiency, etc. This isn't particularly relevant when discussing glide ratio, however, as previously discussed.

Again, however, the specific glide ratio for a given airplane under a given set of conditions really isn't important; the space shuttle has a dismal glide ratio, yet manages to hit it's mark each time, and the glide isn't nearly as important as the landing at the end. Additionally, unless one is far from a suitable forced landing site, then maximizing one's glide is really irrelevant, and minimum sink with a decreased glide ratio may become more important to establish communications, attempt an engine re-start, configure the aircraft or personnel on board for a forced landing, etc.

[Lost man standing]

SN3

Your first paragraph is correct, but irrelevant. Yes glide ratio is also a function of speed and configuration. However if we considering best glide ratio which is close to how we fly a glide, so that can be assumed constant for a given design, it is also close to best rate of climb speed.

My thrust calculation is not wrong, unless there have been some fairly radical advances in physics since I took my degree.

It was was never meant to be accurate. Read it again and note that I said "the maximum thrust from perfect transmission" of the power. I was not assuming this would be achieved. Of course there are losses along the way, but as you point out these are not quantifiable. All we can do without further information is say that the thrust is less than a certain figure (it is common in physics to work out the constraints of a problem if you can't work out the exact answer, before making some esimates or experimental adjustments). I proved that the thrust is constrained to less than the figure required just to remain level. I never considered climb, as we certainly can't do so unless we can remain level. I am aware that rate of climb depends on excess power. I am also aware that angle of climb depends on excess thrust. I am also aware that to achieve either you need excess power and thrust.

By the way, I have ignored one or two factors. I know enough about the issue to judge that they make less difference than the inefficiencies in power to thrust transfer, and we are only making a ballpark calculation. If you know enough to challenge them, then we can discuss whether they are valid.

I calculated what lift was required to sustain level flight, not the power. For that the only information needed is the mass and 9.81 N/kg.

I was not confused by trying to calculate the limit to thrust (I wasn't trying to calculate actual thrust, we don't have enough information). It is the only way we can consider constraints to available lift. Power can only achieve lift through thrust.

Multiplying by three was correct. It does work that way. If lift:drag ratio is 3:1 then the weight that can be sustained in level flight is 3 times the thrust. Thrust equals drag in sustained flight, and lift is three times drag. That's what lift:drag ratio means.

I never suggested it needed three times the thrust to fly. Multiplying by three I was working from drag to lift, not the other way round.

Drag can indeed be determined from the glide ratio given a known weight. Glide ratio is identical to lift:drag ratio. In steady flight thrust=drag and lift=weight. Divide weight by glide ratio and you have the exact thrust required to sustain level flight. This always used to be taught in the ATPL theory, and I assume it still is.

Before you post again, I suggest you go into the books. Most of this discussion is beyond what a typical pilot would ever bother to learn. However denying that lift:drag and glide ratio are equal you have made an error that no ATPL student would, at least not one who was likely to pass the exams. It is one of the basic facts in the syllabus (I could prove it if you like, but diagrams are a pain here so I suggest you look it up). I don't expect a PPL to know necessarily, but if you're going to discuss aerodynamics at ATPL level then it's really necessary.

Where did you get the figures 6:1 and 3:1 anyway? As I said, they are not the figures I have found. The 14:1 comes directly from the manual of a retractable. The 7:1 was from the manual of an aircraft with lovely short wings, so poor glide performance (in fact I think it was 7.3:1). The rest come from various sources, less reliable but consistent. And anyway, think about a C152 in the glide, about 800 feet per minute at 70 kts as far as I recall from teaching in them. That's a bit less than 9:1 at a bit over ideal glide. The Warrior has a wing optimised for low speed, so it has a better glide ratio.

You now admit that the Katana has 14:1, not surprising from the sleek shape and long wings. Why would you assume that a typical light aircraft is so much worse as to give 6:1, and a poor one 3:1? I don't think you realise how that would affect performance, as you were unaware of the lift:drag ratio's relationship with glide ratio.

[Lone_Ranger]

"an airplane with a windmilling propeller glides farther and differently than an airplane with a stopped propeller"


?????...I thought a rotating prop caused more drag than a stationary prop.

BTW, I have zero hours in my log book (I believe your expected to make that clear in here)

[SNS3Guppy]

Power can only achieve lift through thrust.


Power doesn't achieve lift. Wings do that. Perhaps you meant to say that thrust imparts motion causing airspeed, causing lift, but thrust doesn't create lift.

"an airplane with a windmilling propeller glides farther and differently than an airplane with a stopped propeller"


Good catch. That should have been written the other way around. An airplane with a stopped propeller glides farther.

With respect to the glide ratio of the airplane and it's L/D ratio, while in perfect theory the two may be considered mathematically identical, they're not. An airplane in a power off condition which provides a given glide ratio does not provide an equivilent indication of the drag to be overcome in a powered situation, considering the windmiling propeller. A windmilling prop will generate drag in excess of a plywood disc out there, of the same diameter as the prop...that's a lot of drag. To attempt to make a comparison between a gliding airplane with a wind milling prop, and the power required to sustain flight is not the same, and not comparable (is not identical) to the drag incurred in a power-off, windmilling glide.

As an example of a worse-case scenario in a light single, I flew a polish M18 Dromader for about seven years, with several different types of powerplants. These were turbine, but piston vs. turbine is really irrelevant here. With a TPE-331-10 powered airplane, retarding the power to idle produced a glide ratio of approximately 1-2:1; from level flight the airplane could slow down so quickly it would throw me forward in the harness and required application of full forward stick to keep from stalling. It was a useful characteristic for the type of flying we were doing, which involved high angle descents into terain, etc. (not a desireable characeristic in a typical light pleasure airplane).

Despite such a dismal glide ratio, the airplane had excellent performance with the power pushed up. The drag which caused the poor glide ratio was due to the propeller at idle, in a windmilling state. (it wasn't particularly impressive in a failed windmilling state either as I can attest from experience). To equate the glide ratio with the power required to fly the airplane would be a highly incongruous. The L/D ratio in a glide isn't comparable to the L/D ratio under power...and one cannot simply say that an airplane with a small powerplant and a poor glide ratio can't be made to fly on that small power...because the power required to fly isn't the same as the power to overcome the drag in the glide. There's less drag in a powered condition. Glide ratio doesn't necessarily equate to a powered state.

Another airplane which I used to fly, which is no longer in service, was a large four engine airplane with radial piston power. One engine at idle, not feathered, could prevent sustained level flight on the remaining three. While most here aren't going to be flying that kind of an airplane, it's an example of a situation in which only one quarter of the available propellers are producing windmilling drag and yet the airplane is still in a highly impaired state...with three more identical engines still functioning perfectly, attempting to sustain flight. The windmilling prop can produce substantial drag which isn't present during a powered state when the engine is driving the prop...to suggest that the power required to sustain flight is comparable to the drag produced in a windmilling glide is incorrect, and that applies to a light single as much as a large four engine recip.

[Lost man standing]

"Power doesn't achieve lift"

Try telling that to a helicopter pilot.

It does not directly achieve lift. However lift cannot be produced without power, and power produces lift by causing net airflow over the wings. This is achieved in various fashions (I can think of 4 off the top of my head), although for now we are talking about by its use to produce thrust to overcome drag and keep the aircraft with fixed wings moving through the air.

Unless you really are not keeping up with the physics here you are quite aware that my words were short hand. Do I really need to go into detailed, pedantic description, like the previous paragraph, of every idea every time I mention it, even when I have already explained it before?

Yes a windmilling prop provides prop drag. However an engine has to overcome prop drag in order to provide thrust, that is one of the inefficiencies we both alluded to. Therefore it is on both sides of the equation and cancels out (in fact it saps thrust in the powered aircraft by more than the increase of drag after engine failure, as the prop is driven faster).

However all this proves is that you are over complicating the matter. I was never making any attempt to precisely calculate thrust or maximum lift. I was using figures of the correct order of magnitude but deliberately conservative assumptions to simplify the problem to prove that there is no way that an aircraft with typical power to weight ratio of light aircraft could fly level if its glide ratio was 3:1. This I have adequately shown. You are simply nitpicking, and have not addressed the central point.

Using a back-of-the-envelope calculation, simplified but with either conservative or realistic assumptions to either constrain or approximate the answer to a problem is a common technique in physics (conservative assumptions to constrain, realistic assumptions to approximate). I remember at university for example being shown that you could work out in a few seconds how long it takes to boil an egg, from basic priciples and the properties of the egg. It is not meant to be an accurate representation of heat flow in an ovoid shape and does not even attempt to model the denaturing of albumen proteins. However it comes up with about the right figure (I think we got 5 minutes).

What is the relevance of an M18 Dromader to "most light aircraft" that you first posted about? That is a piece of drag-inducing ironwork with a huge engine on the front and a massive prop. It doesn't have the power to weight ratio of a Cessna 172, so of course my scratch calculation is not relevant.

Likewise how is a "large four engine airplane with radial piston power" relevant to most light aircraft?

[SNS3Guppy]

"Power doesn't achieve lift"

Try telling that to a helicopter pilot.


Would you prefer to have a rotor wing discussion instead? Not at all relevant here. However, power is not required for a controlled, autorotative state, either. Power in a fixed wing airplane is not at all required to achieve lift. Try saying otherwise to a sailplane pilot.

However lift cannot be produced without power, and power produces lift by causing net airflow over the wings.


Entirely untrue.

Yes a windmilling prop provides prop drag. However an engine has to overcome prop drag in order to provide thrust, that is one of the inefficiencies we both alluded to. Therefore it is on both sides of the equation and cancels out (in fact it saps thrust in the powered aircraft by more than the increase of drag after engine failure, as the prop is driven faster).


No, not at all. A propeller producing drag in a windmilling state alters the LD ratio substantially such that the glide ratio of an aircraft isn't comparable with a high drag propeller and ingine installation to a situation in which the engine is driving the propeller. The drag incurred, even that imparted to the engine (which does not contribute to airframe drag) in a powered situation, is considerably less than windmilling drag. This is why we feather propellers. Two examples were given of this demonstrating the effects of high drag from a windmilling propeller, but based on the comments at the end of your post, this seems to have gone over your head.

However all this proves is that you are over complicating the matter. I was never making any attempt to precisely calculate thrust or maximum lift. I was using figures of the correct order of magnitude but deliberately conservative assumptions to simplify the problem to prove that there is no way that an aircraft with typical power to weight ratio of light aircraft could fly level if its glide ratio was 3:1. This I have adequately shown. You are simply nitpicking, and have not addressed the central point.


You did attempt to do this, but you were shown to be wrong, as I demonstrated in the case of the Dromader...which experiences a 1-2:1 glide ratio at idle...yet miraculously manages to fly all the same...even at greatly reduced thrust. You didn't find this relevant, for some reason....perhaps simply choosing to dismiss a personal example which shows your point incorrect.

What is the relevance of an M18 Dromader to "most light aircraft" that you first posted about? That is a piece of drag-inducing ironwork with a huge engine on the front and a massive prop. It doesn't have the power to weight ratio of a Cessna 172, so of course my scratch calculation is not relevant.


The M18 is a light, single engine, tailwheel general aviation airplane in common use throughout the world. I used it as an example because I spent seven years flying them. It serves as an example of an airplane with a very low glide ratio (in some of the copies I flew) which is very incongruous to the powered L/D, with the vast majority of it's drag in a glide coming from the propeller. It demonstrates that a low glide ratio in a windmilling state, with the propeller and engine absorbing energy from the airstream, cannot be used to determine how the airplane will fly or on what percentage of power. The fact is, it can be flown at very low power settings, certainly not needing it's rated power to fly...despite having a very, very low glide ratio. In fact, it has nearly the same power to weight ratio of a 172, now that you mention it...so yes, it's relevant.

Likewise how is a "large four engine airplane with radial piston power" relevant to most light aircraft?


I spent several years flying it, and am familiar with it, so I included the example. As a propeller driven aircraft with only one out of four engines windmilling, with three others producing takeoff power...the airplane at times couldn't maintain level flight. It's an interesting study in the effects of windmilling drag in a real world situation...even at twice the power to weight ratio of the 172. The glide ratio can be very low, which doesn't necessarily have a bearing on how much power is required to fly in a powered situation.

You seem to miss the point, or even make light of it by suggesting that the drag which causes the low glide ratio has an identical effect in robbing engine performance such that the glide and the powered level flight or climb are handicapped in the same manner. This is simply not true.

For the original poster, again, the fact remains that the glide ratio is really unimportant; it's the landing at the end which counts, and once more, this is entirely within the purview of the pilot.

[Lost man standing]

How does one produce lift without power?

Power is required for autorotation, otherwise one could autorotate and remain level. I suggest you find a physics text book and look up the meaning of the word power. I can assure you it will talk about conversion of energy. Energy can be in the form of potential energy or in the form of chemical energy before its conversion, but power is by definition simply a rate of conversion of energy.

To try and simplify things for you we'll take a glide speed of 70 kts. At a glide ratio of 3:1 that means a rate of descent of 2363 feet per minute. That is not a rate i would like to see in a light aircraft.

Perhaps you could, instead of trying to nitpick minor factors in a calculation that was never meant to be accurate, factors that are overwhelmed by the scale of extra thrust needed to lift your 3:1 L:D ratio aircraft, you could suggest one that has that ratio.

I have looked up the C152 again, and the estimate I found was 8.75:1 (pretty close to the 9:1 I mentioned earlier). So where are your examples of "most" light aircraft at 6:1? Where is the normal light aircraft, relevant to private flying, with a 3:1 lift to drag ratio?

[vabsie]

LMS / SN3

Admittedly some of what you are saying are slightly over and above my little head, but as long as the conversation is conducted in a good and friendly spirit then it's terrific reading which I'm trying to understand.

As for my original question, SN3's answer was more than sufficient as he managed to put my mind at ease with a detailed explanation and some 1st hand experience examples.

Thanks.

[Lost man standing]

Only his answer is wrong, Vabsie. The examples he gives are not relevant, as they are not typical light aircraft. I am not sure why he mentions single-seat agricultural plane I have never heard of in 20 years involvement in a variety of sides of aviation to a question in private flying.

Typical light aircraft have a much better glide ratio than he suggests, which is important to people who are planning flights, especially if there are areas where an engine failure would lead to a difficult landing - over water, woodland, mountains or other rough terrain. I have a friend who managed to glide just clear of the rough moorland hillside he had an engine failure over. Poor glide ration would have meant he could not have made the glide off the hills, and had he thought like that he would have concentrated on the wrong thing, minimising impact in a poor location, rather than achieving a safe landing in a good one.

SN3 also concentrates on prop drag, which is a problem that can be overcome but is also not as dominant as he suggests. Stopping a propellor cancels out 95% of prop drag, and can be achieved in a light aircraft. However a decision has to be made to do that or concentrate on the glide. Shutting down an engine in a light twin all commercial pilots train in at some point is far more relevant as a demonstration of the prop drag of a light single (similar power per engine) than one of four large radials in a big aircraft. Prop drag is important, but really ain't as much as he suggests. If it was it would be really important to stop the propellor in the glide, but except in marginal conditions it is not.

SN3

Forgot to mention that with that large prop the airflow is much slower than the little prop on a normal light single, so the sum changes giving more thrust under power as well as more drag when windmilling. In fact airflow is something I reckon, on further consideration, I over-estimated in my original equation so the thrust limit is higher than I had guessed. However not by enough to actually let the aircraft fly in practice! In fact a scratch calculation which takes that into account, using just pure Newtonian mechanics of energy and momentum brings in some fundamental physical limitations to efficiency due to speed of airflow. Through a typical 78" diameter prop this gives an even lower thrust limit, around 2,200 N. So actual thrust must be well under 2000 N.

Worked with a larger prop the force gets higher of course (because energy relates to velocity squared, momentum only to velocity, so the same energy produces less change of momentum if the speed change is higher. Force equates to rate of change of momentum), and with a helicopter rotor diameter much higher still, which is how it can fly.

[SNS3Guppy]

Only his answer is wrong, Vabsie. The examples he gives are not relevant, as they are not typical light aircraft. I am not sure why he mentions single-seat agricultural plane I have never heard of in 20 years involvement in a variety of sides of aviation to a question in private flying.


You've never heard of the most common agricultural aircraft in the world, and used in every part of the world where agricultural aviation is conducted? Not that it matters, of course. Clearly the example went over your head, but was used as a worse-case example of a poor glide ratio...with an aircraft that has a power to weight ratio the same as the 172 in the example you created...the airplane you said couldn't possibly fly with a 3:1 glide ratio...yet somehow this airplane manages to do very well with even a lesser glide ratio. You don't get why that's relevant? It couldn't possibly be more relevant. What it does do is use a real-world example to show that you're tack here is far off base. A light single with the same power to weight ratio, a lesser glide ratio...and meets the criteria of your example, and it flies despite your predictions that such flight is impossible. How could this be??

SN3 also concentrates on prop drag, which is a problem that can be overcome but is also not as dominant as he suggests. Stopping a propellor cancels out 95% of prop drag, and can be achieved in a light aircraft. However a decision has to be made to do that or concentrate on the glide. Shutting down an engine in a light twin all commercial pilots train in at some point is far more relevant as a demonstration of the prop drag of a light single (similar power per engine) than one of four large radials in a big aircraft. Prop drag is important, but really ain't as much as he suggests. If it was it would be really important to stop the propellor in the glide, but except in marginal conditions it is not.


It very much is as critical as I suggest...with real-world examples provided to boot. In a typical single engine light airplane at lower altitudes, the average pilot may do more harm than good by stopping the prop due to the altitude lost while attempting to do so, to say nothing of the attention required which might be better served elsewhere. That, however, isn't relevant to the discussion...which first and foremost is why a student pilot shouldn't fear an engine failure in a light airplane...because AGAIN...the glide ratio is unimportant, whereas the landing at the end is important, and is entirely within control of the pilot.

What you have dragged into the conversation, needlessly and incorrectly, is the assertion that an airplane with a low glide ratio and the power to weight ratio of a typical light airplane couldn't fly...and that's not true. The fact is that the glide ratio of the airplane with a windmilling propeller has no bearing on the capability of the airplane to fly when under it's own power. It doesn't.

That's the point of the Dromader, in fact....used because it's a light single with a very low glide ratio under certain installations (as previously repeatedly described), the same power to weight ratio as the Cessna 172 you invoked, yet flies very well under it's own power...because the glide ratio has no bearing on the way it flies under it's own power.

Most light airplanes do well without power, because power doesn't create lift, contrary to your own assertions, and can easily trade altitude for airspeed (and thus lift) without any benifit of engine power or thrust, and even in the presence of propeller drag.

There's a reason why some propellers are featherable...because drag is so high.

Point being, your original assertions are incorrect, in the parallel you attempted to draw between powered flight and a windmilling glide. Most light airplane glide ratios are provided given a windmilling glide...and any references to stopped propellers are thus irrelevant to the discussion. You attempted to state that an airplane with a low glide ratio simply can't fly given the power a typical light airplane has...and clearly you're wrong....just as you're incorrect regarding the amount of drag a windmilling propeller creates and the energy it absorbs...again, in excess of the equivilent flat-plate area of the prop disc in many cases.

Forgot to mention that with that large prop the airflow is much slower than the little prop on a normal light single, so the sum changes giving more thrust under power as well as more drag when windmilling.


Your statement makes no sense. "Slower airflow" produces more thrust, you say? What are you trying to say when you say that a large propeller produces slower airflow? Are you trying to say a larger propeller is operated at a slower speed? You're invoking "newtonian physics," and attempt to suggest that moving mass airflow at a slower speed produces more "thrust?" By definition that defies several laws of physics, and while both interesting and incorrect, is also not particularly relevant to the original posters question, or your own assertions.

Shutting down an engine in a light twin all commercial pilots train in at some point is far more relevant as a demonstration of the prop drag of a light single (similar power per engine) than one of four large radials in a big aircraft.


Okay. I've also been unable to maintain altitude in a King Air 90 when a prop wouldn't feather. Also in an Apache. A Cessna 310. A seminole. Yada, yada, yada. Same thing, just not as clear an example of what happens to the airplane with good engines, even multiple good engines, fighting the drag of a single windmilling propeller. Yet another example that sailed right over your educated, newtonian head, in it's 20 year exposure to "a variety of sides of aviation.

You're not going to try to invoke rotor-wing flight again, are you?

Typical light aircraft have a much better glide ratio than he suggests, which is important to people who are planning flights, especially if there are areas where an engine failure would lead to a difficult landing - over water, woodland, mountains or other rough terrain. I have a friend who managed to glide just clear of the rough moorland hillside he had an engine failure over. Poor glide ration would have meant he could not have made the glide off the hills, and had he thought like that he would have concentrated on the wrong thing, minimising impact in a poor location, rather than achieving a safe landing in a good one.


You've never had an engine failure resulting in a forced landing, have you? Your thought process in the matter is still academic, based on what friends did and what you've read...perhaps it's easy to understand, then, why you don't seem to get it. It's becoming clearer.

Worked with a larger prop the force gets higher of course (because energy relates to velocity squared, momentum only to velocity, so the same energy produces less change of momentum if the speed change is higher. Force equates to rate of change of momentum), and with a helicopter rotor diameter much higher still, which is how it can fly.


Ah, well. You're really spinning off into left field now, and have returned to your helicopter discussion. You'd be far better off, and everyone better served, by starting a separate thread to tackle rotor-wing discussions, as they have NO bearing on the question asked by a student-pilot in this thread. What you are managing to do is little more than add incorrect information and confusion to a very simple question. Once again, we're talking about airplanes, here. Not helicopters. You seem to be troubled by examples using light single engine tailwheel airplanes and multi engine airplanes, but have no difficulty trying to introduce the dynamics of the helicopter.

That aside, your last paragraph makes no sense. Try it again.

How does one produce lift without power?


AIRSPEED!!!!!

Have you ever flown an airplane?

Have you ever seen a sailplane? Ever flown one? Ever shut off the engine in a light airplane and glided for a while? Lift is still produced, even with no power. Even with no engine. Imagine that. Airplanes even go back up, even perform entire aerobatic routines with full control, and plenty of lift...all with no power. Does this dazzle your mind? It really shouldn't.

Power is required for autorotation, otherwise one could autorotate and remain level. I suggest you find a physics text book and look up the meaning of the word power. I can assure you it will talk about conversion of energy. Energy can be in the form of potential energy or in the form of chemical energy before its conversion, but power is by definition simply a rate of conversion of energy.


Okay...you're back to helicopters again. Try to focus, will you? We're talking about AIRPLANES. The ones with the wings that don't spin around...take some time, look at some pictures, you'll see the difference. You appear rather confused.

I really have to question if you have any experience or training or education in flying an airplane at all. You don't seem to have a clue what you're talking about. I'll help you out, and then I think it's time to dismiss you as a troll and move on. A helicopter under autorotation is operating with the transmission clutch disengaged; the rotor is not under engine power or the influence of engine power at all. When we speak of powered flight, we speak of various types of internal combustion engines (in most cases) producing power to drive a propeller or rotor, or to produce jet thrust. A helicopter descending in an autorotative state is not doing so under an engine driven rotor, and is not in a powered state. This appears to be a new concept to you, or perhaps you're just overly arguementative...but your arguements have left the realm of rational discussion, relevant discussion, and now you're talking stupidly.

The only exception to powered autorotative flight is the autogryo, or gyroplane, in which the aircraft operates continuously in an autorotative state under power, despite the fact that the rotor itself isn't powered. That's far afield from the original poster's question, and as he's already stated that he's received the answer he desired, I'll end my discussions with you now, and leave you to your ramblings.

[Lost man standing]

SN3

Ag planes are rarely if ever used in the countries where I fly most. I have no interest in ag flying. Why should I have heard of such a plane? Why does it have any relevance to private flying? What proportion of private pilots fly them?

There is one comment you make that proves you misunderstood all the relevant physics, therefore this is a bit of a pointless conversation. It is the response to my query about how to produce lift without power, by saying "airspeed".

Of course it is impossible to achieve any airspeed (above windspeed), or sustain airspeed against drag, without converting energy. Conversion of energy is power.

A sailplane uses the power in converting potential energy to kinetic energy to produce airflow and thus lift, and takes kinetic energy out of rising air to convert to potential energy and to kinetic energy in another direction. To a physicist that is still power. Power is just rate of conversion of energy. Without power a sailplane cannot fly.

I introduced the helicopter as an extreme example in the consideration of energy used to produce given thrust. The same power producing slower airflow has to move more air and will provide higher thrust. Large props produce low speeds of flow, and note that speed of airflow comes into all the calculations, so large props behave differently. It is standard physics, the same reason a high-bypass turbofan is more efficient than a turbojet. I was talking specifically about propellors, and in physical terms a rotor is a very large propellor, so it was relevant. It should be obvious that an R44 produces far more thrust from its 205 hp than an Arrow does from 200 hp, or the later would be able to hover on its prop.

Helicopters are also relevant if you start to make wild statements like "power doesn't achieve lift". It is a more direct example of power doing just that.

Note I never denied that a prop creates drag, but nor was I trying to make an accurate calculation, as the data are not easily available. In fact I pointed out that it always produces drag. However prop drag is related strongly to prop diameter as is thrust produced by a given power. That is why power of an aircraft with a large prop diameter and poor glide ratio is irrelevant to consideration of something like a PA28 or a 172, with a tiny prop which has a small, although measurable effect on glide ratio (or so I am told by someone who stopped it in the glide, cutting out 95% of prop drag, and made it a little further than otherwise, critically over the airfield fence).

You still haven't come up with any typical GA aircraft with a glide ratio less than 7:1. So what is the point of arguing the case for an ag plane that is irrelevant?

[cats_five]

<snip>
Which single engine aeroplane would be rated as having the best "gliding" potential ... would it be a little cessna 152 or rather something like a pa28?
<snip>


Taking your title to the thread (best single engine glider) very literally, probably one of these two:

Lange Aviation - Antares 20E - Intro (http://www.lange-aviation.com/htm/english/products/antares_20e/antares_20E.html)
ASH 30 Mi (http://www.alexander-schleicher.de/produkte/ash30/ash30_main_e.htm)

Both about 60:1 I believe.

And to the folks talking about a low aerotow launch failure, a low winch launch failure is also horribly entertaining for the few seconds it takes to get back on the ground. :eek:

[Islander2]

SNS3Guppy said:
Most light airplanes have a glide ration which approximates about a 6:1 ratio or so, though some as little as 3:1.I've come late to this discussion, so will merely observe that SNS3's observation is wildly inaccurate.

The vast majority of light aeroplanes actually have best-glide ratios in the range 9:1 to 12:1 (just over 10:1 in the case of my A36 Bonanza), although a small number of examples can be found either side of these boundaries. Modern jet airliners do somewhat better at >15:1, and high performance sailplanes can be up around 60:1.

[BeechNut]

From my Beech C23 (Sundowner) POH:

"Glide distance is approximately 1.7 nautical miles per 1000 ft of altitude above the terrain".

Doing the math, that gives a 10.3:1 glide ratio.

Beech

[BelArgUSA]

Just to throw this into your discussion...
The glide ratio of a 747 is close to 18:1 -
My answer to those who say "a jetliner glides like a brick" -
My opinion - lightplanes glide like bricks.
xxx
Often played the game of IDLE descents from FL390 to 1000 ft AGL/MSL -
Gliding distance is generally 110/120 NM (no wind factor) -
xxx
Oh sure... I admit there is residual thrust of the 4 engines...
We do not shutdown the motors at TOD and relight at outer marker to impress you further.
xxx
Now ready to be accused of reckless flying -
Trouble is, among the many who practiced similar games were... chief pilots.
Yes yes, I know - with YOUR airline, you are professionals and do not indulge in such.
xxx
:8
Happy contrails

[larssnowpharter]

Best Single Engine Glider?

Something along the lines of an ASH 25e or a Stemme S10?

[englishal]

In my experience (Math(s) aside), 10:1 is realistic for most light aeroplanes.

The main thing is that they normally don't drop like a brick. The pilot often messes up the emergency landing though, but that is another story. I see on the BBC website today (31.08) someone in Devon made a sucessful emergency landing into a marsh / boggy land or all places. Good one :ok:

[Fitter2]

Not a Stemme S-10, although it's a good compromise between an aircraft capable of touring and an adequate performance glider. I offended an owner by suggesting after flying one that it was almost as good as having a glider................

Currently either the Eta or the Binder EB-28, both of which are self launching 2-seater sailplanes with a best glide (engine off and retracted) in excess of 60:1

http://i35.tinypic.com/24dge53.jpg

EB28. The 28 is for wingspan in metres.

However, while that answers the original question,I don't think it's whet the thread starter meant.

[SNS3Guppy]

I introduced the helicopter as an extreme example in the consideration of energy used to produce given thrust. The same power producing slower airflow has to move more air and will provide higher thrust.


It's an extreme example because it's irrelevant. You're attempting to say that moving airflow more slowly produces higher thrust, which is contrary to basic physics. Now, if you were attempt to say that a substantially larger propeller disc with more area moves more airmass, then that would be correct, but it has nothing to do with the propeller speed.

We manage it in a turboprop engine at substantially slower speeds, but the RPM isn't relevant...the size of the prop and the design of the blades, as well as the angle of attack coupled with a greater torque capacity mean that more air can be moved. Light single engine piston propeller driven airpalnes have limited RPM ranges, limited propeller options, and are really no comparison to a helicopter...so introducing the helicopter is a ridiculous example.

Large props produce low speeds of flow, and note that speed of airflow comes into all the calculations, so large props behave differently. It is standard physics, the same reason a high-bypass turbofan is more efficient than a turbojet.


A turbofan is more efficient at lower altitudes, where the fan does more of the work. However, it's also a ridiculous comparison, particularly in light of the fact that most piston powered light general aviation single engine airplanes aren't turbofan powered, or turbojet powered, and the differences between the two are substantial notwithstanding the light airplane. In particular attempting to compare a propeller with a ducted fan, and a two or three blade direct driven propeller against a multi-blade ducted fan free-spool powerplant...just doesn't wash.

I was talking specifically about propellors, and in physical terms a rotor is a very large propellor, so it was relevant. It should be obvious that an R44 produces far more thrust from its 205 hp than an Arrow does from 200 hp, or the later would be able to hover on its prop.


If you were to attempt a reasonable comparison in your wild example it would be to compare the component of lift from the rotor used in forward flight, to the motive force in forward flight imparted the propeller of the Arrow...and you'd find that the propeller of the arrow is producing a substantially higher force with respect to propelling the aircraft foward through the air...and in fact even then the comparison wouldn't be adequate because of the translational lift differences of the helicopter in forward flight.

You're simply confusing the topic with ridiculous comparisons...such as the introduction of a helicopter into a discussion of glides in a fixed wing airplane.

Helicopters are also relevant if you start to make wild statements like "power doesn't achieve lift". It is a more direct example of power doing just that.


Power does not achieve lift. In the case of a helicopter, you're confused between the relative motion of the rotor...which will turn with or without power (visit autorotation), and which operates under very different principles. It's not a big propeller; it's a big wing, and it's purpose, aerodynamics, and principles are not the same as a propeller, nor is it's use. A helicopter rotor isn't a propeller; it's a wing that rotates...hence the term rotary wing.

A better comparison might be an autogyro with a propeller being driven by an engine, and a rotor producing lift in a state of autorotation. The difference between a state of auto-rotation and a driven rotor state is two-fold. The obvious difference is the motive force to turn the rotor, but the clear difference is the direction of airflow through the rotor plane.

Of course, you seem to have trouble understanding how the introduction of a light single engine piston powered general aviation airplane relates to a conversation involving light single engine piston powered general aviation airplanes...so it's no surprise that you're confused.

[Chuck Ellsworth]

Lost Man standing, my hat is off to you attempting to discuss flying with SNS3Guppy.

There was a time when I was tempted to but decided the effort was not worth it because it would not really change the way the world evolves, you see SNS3Guppy has done it all and none of us unwashed mortals know anything about flying.

This bit I clipped out says it all.
Quote:

SNS3Guppy said:
Quote:
Most light airplanes have a glide ration which approximates about a 6:1 ratio or so, though some as little as 3:1.

Quote from Islander2:

I've come late to this discussion, so will merely observe that SNS3's observation is wildly inaccurate.

For sure it is entertaining non the less.

[Lost man standing]

Cheers Chuck.

It's fun though, and ever since school and my degree physics has been a kind of hobby with me, so it is interesting to go through the processes SN3's misunderstandings of basic physics force upon me.

SN3

Still no actual, relevant examples?

If you move more air (say by using a larger prop) with the same power then it moves more slowly than moving a small amount of air with the same power. However because there is more mass flow the thrust is actually higher. Thus the size of prop is critical in understanding the issue we are talking about (note that I never mentioned propellor speed at all. I am not sure where you got that from).

That is why the helicopter rotor is relevant. It is nothing to do with the forward component of lift causing the forward motion of as helicopter, that really is irrelevant and I have no idea why you brought it in. It is to do with how a large prop compares with a small prop in terms of producing thrust from a given power. A helicopter rotor moves a larger amount of air than an aircraft prop, at a lower speed given the same power. The helicopter is straight-forward proof of this. An R44 rotor can produce thrust greater than its own max all-up weight in order to hover using only 205 hp. An Arrow with only 5 hp less could not hover on its prop even with only a pilot on board and a small amount of fuel, when it would be lighter than the R44.

Just because you say it ain't so doesn't mean it isn't, or a lot of 777s with their nice high-bypass turbofans would have started crashing just as you said it!

I can prove it with a few equations if necessary, but it is rather irrelevant if you are unable to understand those equations. If you could understand them they should be irrelevant, if I give the following description.

Energy is 1/2mv^2 and momentum is mv. Power is rate of change of energy, and force is rate of change of momentum (thrust is a force). So take m to be the mass of air passing in a second, v its change of velocity, mv is then momentum change in a second, i.e thrust and 1/2mv^2 is energy conversion in a second, i.e. power.

So increasing the mass flow by a factor of x at the same power reduces the velocity by a factor √x. The thrust is proportional to the mass flow and velocity, so is multiplied by a factor of x/√x. This is √x. So at the same power, reducing the speed of the airflow increases the thrust, as I said in the first place! Double the mass flow you have 41% more static thrust.Power does not achieve lift. In the case of a helicopter, you're confused between the relative motion of the rotor...which will turn with or without power (visit autorotation)How does a rotor achieve relative motion without power?

Autorotation requires power. The rotors require power to start moving and to overcome drag and friction in all its various forms. The power in autorotation is the conversion of potential to kinetic energy. It's still power, even if it doesn't involve chemical energy!

You really don't understand what power is, do you? I say again: power is the rate of conversion or transfer of energy. Nothing more, nothing less. It does not require machinery. It can come from the burning of fossil fuel, the falling of a weight or the differential heating of the Earth's surface. It's still power!

An autogyro is not a better example. I wanted a more direct example of motive, mechanical power (i.e. what you already accepted as power, as I didn't at the time feel the need to teach you basic physics) producing lift than a fixed-wing aircraft, which does it by producing thrust, which moves the aircraft, which causes airflow across the wing which then produces lift. The helicopter just uses power to movement of a wing that produces lift. You then come up with an autogyro, which does use power to produce lift but in an even more roundabout way than a fixed-wing aircraft!Of course, you seem to have trouble understanding how the introduction of a light single engine piston powered general aviation airplane relates to a conversation involving light single engine piston powered general aviation airplanes...so it's no surprise that you're confused.Have you ever actually read the title of the forum? Do you know what "Private Flying" is? Have you noticed that there is a separate forum for "Biz Jets, Ag planes GA etc." flying, in which an answer including an ag plane might indeed have been relevant?

The matching number of engines and the power plant type are beside the point, as is the fact that it is a GA aircraft. The fact that it is not used for "Private Flying", the entire purpose of this forum, means it is irrelevant to the discussion.

[Chuck Ellsworth]

Lost man Standing, I am not anywhere near educated enough to understand the math behind the physics of flying as I am a mere pilot who was fortunate to have worked at many different types of flying during my career, SNS3Guppy has brought Ag Flying into the mix and it brought back fond memories of years long passed......

...seeing as this is a private pilot forum I am attaching a story I wrote about my first flying job.....if it bores people they can just skip it, if they like it then there was nothing lost by posting it.

************************************************************

The Tobacco Fields - By Chuck Ellsworth

For generations the farmers of southern Ontario have planted cared for harvested and cured tobacco in a small area on the northern shores of lake Erie. Our part in this very lucrative cash crop was aerial application of fertilizers and pesticides better known as crop dusting.

At the end of the twentieth century this form of farming is slowly dying due to the ever-increasing movement of the anti-smoking segment of society. Although few would argue the health risks of smoking it is interesting that our government actively supports both sides of this social problem. Several times in the past ten or so years I have rented a car and driven back to the tobacco farming area of Southern Ontario, where over forty years ago I was part of that unique group of pilots who earned their living flying the crop dusting planes.

The narrow old highways are still there, but like the tobacco farms they are slowly fading into history as newer and more modern freeways are built. The easiest way of finding tobacco country is to drive highway 3, during the nineteen forties and early fifties this winding narrow road was the main route from Windsor through the heart of tobacco country and on to the Niagara district. Soon after leaving the modern multi lane 401 to highway 3 you will begin to realize that although it was only a short drive you have drifted back a long way in time. Driving through the small villages and towns very little has changed and life seems to be as it was in the boom days of tobacco farming, when transients came from all over the continent for the harvest. They came by the hundreds to towns like Aylmer, Tillsonberg, Deli and Simcoe, these towns that were synonymous with tobacco have changed so little it is like going back in time.

Several of the airfields we flew our Cubs, Super Cubs and Stearmans out of in the fifties and early sixties are still there. Just outside of Simcoe highway 3 runs right past the airport and even before turning into the driveway to the field I can see that after all these years nothing seems to have changed. I could be in a time warp and can imagine a Stearman or Cub landing and one of my old flying friends getting out of his airplane after another morning killing tobacco horn worms, and saying come on Chuck lets walk down to the restaurant and have breakfast. The tobacco hornworm was a perennial pest and our most important and profitable source of income. Most of my old companion's names have faded from memory as the years have passed and we went our different ways but some of them are easy to recall.

Like Lorne Beacroft a really great cropduster and Stearman pilot. Lorne and I shared many exciting adventures in our airplanes working together from the row crop farms in Southern Ontario to conifer release spraying all over Northern Ontario for the big pulp and paper companies. Little did we know then that many years later I would pick up a newspaper thousands of miles away and read about Lorne being Canadas first successful heart transplant. I wonder where he is today and what he is doing?

There are others, Tom Martindale whom I talked to just last year after over forty years, now retired having flown a long career with Trans Canada Airlines, now named Air Canada. Then there was Howard Zimmerman who went on to run his own helicopter company and still in the aerial applicating business last I heard of him. And who could forget Bud Boughner another character that just disappeared probably still out there somewhere flying for someone.

I have been back to St. Thomas, another tobacco farming town on highway 3 twice in the last several years to pick up airplanes to move for people in my ferry business. The airport has changed very little over the years. The hanger where I first learned to fly cropdusters is still there with the same smell of chemicals that no Ag. Pilot can ever forget. It is now the home of Hicks and Lawrence who were in the business in the fifties and still at it, only the airplanes have changed.

My first flying job started in that hangar, right from a brand new commercial license to the greatest flying job that any pilot could ever want. There were twenty-three of us who started the crop dusting course early that spring, in the end only three were hired and I was fortunate to have been one of them.

With the grand total of 252 hours in my log book I started my training with an old duster pilot named George Walker. Right from the start he let me know that I was either going to fly this damned thing right on its limits and be absolutely perfect in flying crop spraying patterns or the training wouldn't last long. It was fantastic not only to learn how to really fly unusual attitudes but do it right at ground level.

To become a good crop duster pilot required that you accurately fly the airplane to evenly apply the chemicals over the field being treated. We really had to be careful with our flying when applying fertilizers in early spring as any error was there for all to see as the crop started growing. This was achieved by starting on one side of the field maintaining a constant height, airspeed and track over the crop. Just prior to reaching the end of your run full power was applied, and at the last moment the spray booms were shut off and at the same time a forty-five degree climb was initiated. As soon as you were clear of obstructions a turn right or left was made using forty five to sixty degrees of bank. After approximately three seconds a very quick turn in the opposite direction was entered until a complete one hundred and eighty degree change of direction had been completed. If done properly you were now lined up exactly forty-five feet right or left of the track you had just flown down the field.

From that point a forty-five degree dive was entered and with the use of power recovery to level flight was made at the exact height above the crop and the exact airspeed required for the next run down the field in the opposite direction to your last pass. Speed was maintained from that point by reducing power.

To finish the course and be one of the three finally hired was really hard to believe. To be paid to do this was beyond belief. When the season began we were each assigned an airplane, a crash helmet, a tent and sleeping bag and sent off to set up what was to be our summer home on some farmers field. Mine was near Langdon just a few miles from lake Erie.

Last year I tried without success to find the field where my Cub and I spent a lot of that first summer. Time and change linked with my memory of its location being from flying into it rather than driving to it worked against me and I was unable to find it. Remembering it however is easy, how could one forget crawling out of my tent just before sunrise to mix the chemicals? Then pump it into the spray tank and hand start the cub. Then to be in the air just as it was getting light enough to see safely and get in as many acres as possible before the wind came up and shut down our flying until evening. Then with luck the wind would go down enough to allow us to resume work before darkness would shut us down for the day. The company had a very good method for assuring we would spray the correct field.

Each new job was given to us by the salesman who after selling the farmer drew a map for the pilots with the location of the farm and each building and its color plus all the different crops were written on the map drawn to scale. As well as the buildings all trees, fences and power lines were drawn to scale. It was very easy for us to find and positively identify our field to be sprayed and I can not remember us making any errors in that regard.

Sadly there were to many flying errors made and during the first three years that I crop-dusted eight pilots died in this very demanding type of flying in our area. Most of the accidents were due to stalling in turns or hitting power lines, fences or trees.

One new pilot who had only been with us for two weeks died while doing a low level stall turn and spinning in, he was just to low to recover from the loss of control. He had been on his way back from a spraying mission when he decided to put on an airshow at the farm of his girlfriend of the moment. This particular accident was to be the last for a long time as those of us who were flying for the different companies in that area had by that time figured out what the limits were that we could not go beyond.

Even though there were a lot of accidents in the early years they at least gave the industry the motivation to keep improving on flying safety, which made a great difference in the frequency of pilot error accidents. Agricultural flying has improved in other areas as well especially in the use of toxic chemicals.

In 1961 Rachel Carson wrote a book called "The silent spring. " This book was the beginning of public awareness to the danger of the wide area spraying of chemicals especially the use of D.D.T. to control Mosquitoes and black flies.

For years all over the world we had been using this chemical not really aware that it had a very long-term residual life. When Rachels book pointed out that D.D.T. had began to build up in the food chain in nature, she also showed that as a result many of the birds and other species were in danger of being wiped out due to D.D.T. Her book became a best seller and we in the aerial application business were worried that it would drastically affect our business, and it did.

The government agency in Ontario that regulated pesticides and their use called a series of meetings with the industry. From these meetings new laws were passed requiring us to attend Guelph agricultural college and receive a diploma in toxicology and entomology. I attended these classes and in the spring of 1962 passed the exams and received Pest Control License Class 3 - Aerial Applicator.

My license number was 001. Now if nothing else I can say that I may not have been the best but I was the first. Without doubt the knowledge and understanding of the relationship of these chemicals to the environment more than made up for all the work that went into getting the license. From that point on the industry went to great length to find and use chemicals less toxic to our animal life and also to humans.

It would be easy to just keep right on writing about aerial application and all the exciting and sometimes boring experiences we had, however I will sum it all up with the observation that crop dusting was not only my first flying job it was without doubt the best. I flew seven seasons' crop dusting and I often think of someday giving it another go, at least for a short time.

[micromalc]

OK, so I had the pleasure of flying a Stemme S10 recently, what a joy, a ratio of 50-1, side by side seating and an engine that can push you along at
100 mph. A great aircraft, but, at what a cost, over £150000. So if you cant afford that try popping over to Enstone (Chipping Norton)and try out their lovely Super Dimona, it has an excellent glide ratio, so if the engine fails you should have enough time to sort out a suitable landing zone. It has great air brakes which make it reasonably easy to get into most fields.

[SNS3Guppy]

An autogyro is not a better example. I wanted a more direct example of motive, mechanical power (i.e. what you already accepted as power, as I didn't at the time feel the need to teach you basic physics) producing lift than a fixed-wing aircraft, which does it by producing thrust, which moves the aircraft, which causes airflow across the wing which then produces lift. The helicopter just uses power to movement of a wing that produces lift. You then come up with an autogyro, which does use power to produce lift but in an even more roundabout way than a fixed-wing aircraft!


Your examples get more idiotic by the moment. When you find a helicopter with a rotor diameter the same as the propeller on the arrow, then you'll have your comparison. An autogyro has a propeller which achieves thrust in the same way as the arrow, and is therefore a better comparison, while the rotor remains in a state of autorotation providing lift...just as the arrow's fixed wing produces lift.

Put a propeller on the arrow the same diameter with the same blade area and properties as the rotor on the helicopter, and find a way to get it in the air without striking the prop...and you'll have a rough comparison. However, you won't be able to make one between the arrow as it stands, and a helicopter (particularly with respect to gliding); no comparison between lift, thrust or drag.

Are you thick enough you can't tell the difference between an airplane and a helicopter? Someone allows you to pilot an aircraft in that condition?

You really don't understand what power is, do you? I say again: power is the rate of conversion or transfer of energy. Nothing more, nothing less. It does not require machinery. It can come from the burning of fossil fuel, the falling of a weight or the differential heating of the Earth's surface. It's still power!


Also irrelevant in light of your assertions that an aircraft with a limited glide ratio couldn't fly on the power provided by a light airplane engine. That was your assertion before...which is wrong. In fact falling back to your ther-world helicopter example...you're not going to find a helicopter with an impressive glide ratio in autorotation (or for you, an autorotative-powered state, if you wish)...never the less, without needing an ungodly amount of engine power, it flies, hovers, and returns to land intact.

You asserted that an aircraft with a low glide ratio couldn't do it...it was this ridiculous assumption which kicked off the discussion, and the fact of the matter is that the glide ratio isn't necessarily indicative of what the aircraft can do under power. Several examples have been provided of aircraft with power to weight ratios approximating most light airpalnes in which glide ratio was very poor with power reduced by varying percentages...yet the airplanes managed to do very well under power.

Again, to the point of the original poster (which you never found, and what bit you did, you apparently lost very early on)...the glide ratio isn't particularly important; it's what occurs at the end that counts. That applies every bit as much in an airplane as in a helicopter.

[Lost man standing]

Sounds fantastic Chuck. I knew a helicopter Ag pilot, actually US Coast Guard when I met him. Great guy, lots of stories with brilliant sense of humour and turn of phrase - "went down like a waxed piano". Very outgoing for rotary!

SN3

Still no examples of light aircraft commonly flown privately with a glide ratio less than 7:1? When you find a helicopter with a rotor diameter the same as the propeller on the arrow, then you'll have your comparisonThe entire point is that a helicopter’s rotor, while being aerodynamically a propeller, has to be very large in order to produce a lot of thrust. If a helicopter of a reasonable weight and power existed with a rotor the size of an Arrow’s prop then it would in fact support your view, not mine. If you will only accept the relevance of non-existent aircraft that would prove your mistaken physics then we are really not going to get very far. The whole relevance to my point is in the difference in size between the Arrow prop and the R44 rotor.

I think your confusion is in assuming that thrust has to be forward. Of course the lift of a helicopter is just thrust produced in an upward direction. That is the thrust I am talking about. An autogyro is an irrelevance only introduced by you. It has nothing to do with any of the points I have made, as the big propeller on the top is not powered directly by the engine, so cannot illustrate the greater thrust produced by an engine coupled to a larger prop.

The meaning of power cannot be irrelevant if we are talking about power. So far you have clearly shown that you have misunderstood the meaning at every mention.

The difference between a helicopter and an aeroplane is clear to me. That is why I only used the helicopter to illustrate that power can be used to produce lift and that a large propeller produces more thrust than a small propeller, given the same power.

You on the other hand have just done exactly what you said incorrectly I had done, and mistaken a helicopter for an aeroplane. Since a helicopter flies in a completely different way to an aeroplane none of my arguments apply to a helicopter. Yet you use a helicopter as a counter example. Therefore either you have been unable to follow any of the discussion and are really lost, or you really think aeroplanes and helicopters fly in a similar way. So if you thought I was thick when you mistakenly believed I had made that error, what do you think of yourself now that you have?

No-one “allows” me to fly aircraft, thanks. I authorise myself, and others, to fly aircraft. That is my job, along with ensuring that when we fly we all fly safely.

I never denied that an aircraft with poor glide ratio could fly with limited power by the way. What I pointed out was that a typical GA design would not fly if it had a glide ratio that poor, because of the relationship between glide ratio and lift to drag ratio. I really do mean it, if you just tripled the drag on these aircraft they genuinely wouldn’t fly. I am bemused by the fact that you think they would.

Perhaps you are right that someone here should be kept away from all aircraft!

Actually I don’t think that is the case. I don’t think you are stupid at all. I think you are just hide-bound and stuck in simplified concepts you were taught years ago in principles of flight groundschool, perfectly good enough for flying but not useful beyond that. Concepts like thrust only being along the line of travel. Either your physics wasn’t up to any really deep understanding of those concepts and their inter-relationships or more likely you simply were not that interested.

[SNS3Guppy]

What I pointed out was that a typical GA design would not fly if it had a glide ratio that poor, because of the relationship between glide ratio and lift to drag ratio.


Yes, you did so incorrectly, as previously demonstrated. The glide ratio is not merely the function of the L/D ratio of the powered airplane; the L/D ratio of the airplane with a windmilling propeller is not the same as one under it's own power (let's be clear; it's own engine power...before you run off another semantic rant). As discussed, a light single engine airplane may very well demonstrate a very poor glide ratio, yet perform admirably under it's own power with the same power to weight ratio as most other single engine light airplanes (and in one example you didn't seem to comprehend, an airplane which has lost 25% of it's thrust and was unable to fly, performed admirably without the drag of a single windmilling propeller and it's 25% thrust restored...that's just a quarter of the thrust...not even the difference between a complete power off glide and a powered climb).

The original poster was interested in airplanes that glide well, for safety, and the bottom line again, and for the last time is that he needn't worry. The distance the airplane can glide is superfluous and unimportant when considering if the airplane is safe. It's the pilot that makes it safe, and distance isn't at all important when one keeps a viable landing site beneath on at all times.

I've had enough of you. You're on the ignore list now too.

[Contacttower]

One common GA type which is actually a very good glider...especially with the prop fully back is the Firefly, nice long wings and very light construction. Otherwise 500ft lost per NM seems about good to average for a light aircraft.

[airplanesey]

i hope i am not confusing things even more, but something just occured to me...

wouldnt the better glider need a longer landing distance? surely that would mean the aircraft that glides less would be better in an emergency situation as it could land in a shorter field, right:confused:

please forgive me if this post is nonsence, im still in very early days of my PPL...

[SNS3Guppy]

airplanesy,

That makes sense, but it's not necessarily so.

What a higher glide ratio, or flatter glide does for you is allow you a wider range of options in the event you must glide. It doesn't mean you must maintain that rate of descent for the entire descent, or even that descent angle.

Think of it this way; you can always increase the descent rate or angle with a slip, with flaps, with spoilers, or simply by flying a different angle of attack (airspeed), by putting out gear, and so forth. You can make an airplane with a significant glide ratio descend steeper...but you really can't make an airplane with a poor glide ratio go flatter or farther.

The landing distance is a function of approach speed, weight, configuration, and pilot technique. The slower you approach, the shorter the landing distance. Putting the airplane down where you want in order to make the most of the available space is pilot technique. A lighter airplane is easier to get stopped than a heavy airplane, to a point, and the way you configure (flaps, etc) and the way you use that configuration makes a big difference.

An airplane that's a great glider can still be set down just like any spot landing; thats up to you. You can always slip.

An airplane with a very limited glide ratio can't be upgraded...you can pitch up, increase angle of attack, and sacrifice airspeed and energy a brief decrease in descent rate...but that's about it. It's never really going to get better. An airplane with a higher glide ratio can always be degraded to get down, and if you find you've misjudged and you're slipping to make your landing spot, you can always stop slipping and readjust your landing point. If you've misjudged in the airplane with the lower glide ratio, you're out of luck.

It's for that reason that being high is better than being low during a forced landing. No matter what the glide ratio. You can always do more to get down...but if you're truly on your way earthward, you can't do a lot to go back up unless you're in a sailplane, have ridge lift, or you can find some lift along the way. Erring on the side of safety by staying a little high and bleeding it off with flaps or a slip or other means is better than finding one's self short and low and slow and having no way to recitify the situation.

Be on speed and in practice...it's the best defense against calamity in a forced landing. A prepared state of mind is much more important than how far you can glide; prepare mentally and prepare physically (keep forced landing sites available) is the key.

[Chuck Ellsworth]

. The distance the airplane can glide is superfluous and unimportant when considering if the airplane is safe. It's the pilot that makes it safe, and distance isn't at all important when one keeps a viable landing site beneath on at all times.


So how does a pilot make a safe landing if he/she is flying one of those airplanes with a glide ratio of 3:1 and there are only tall trees and big rocks below, yet just a little further away is an airport that a light aircraft such as a Cessna 150 with a glide ratio of 8:1 would be able to glide to with altitude to spare?

Just exactly what magic or superman skills would this " safe " pilot have that would trump the ordinary pilot in the airplane that could glide to the airport?


The distance the airplane can glide is superfluous and unimportant when considering if the airplane is safe.

That kind of statement has no place in a forum meant for private pilots as it may influence some newbie to actually believe such garbage.

[Chuck Ellsworth]

Lost Man Standing, I finished my Ag. years flying the Hughes 300, but my true love is the Stearman with the P&W 985.

By the way of all the flying devices I flew over the decades the most fun is the gyroplane.....why I even managed to get a US Commercial Gyroplane Pilots License. :ok:

[SNS3Guppy]

Come now, chuck. Even you aren't that stupid. You're just being difficult.

A landing site beneath the aircraft, for which one has no need to glide negates any significance of a glide ratio. You understand that if one has no need to glide anywhere, and one has exercised good airmanship by keeping a forced landing site beneath ones self and accessible given the type of aircraft which one is flying...then the actual glide ratio is irrelevant. You get this, right?

Chuck, you really need to work on your comprehension skills.

[airplanesey]

sns3guppy, i appreciate your response. that does make alot of sense.

thanks:ok:

[Pace]

>So how does a pilot make a safe landing if he/she is flying one of those airplanes with a glide ratio of 3:1 and there are only tall trees and big rocks below, yet just a little further away is an airport that a light aircraft such as a Cessna 150 with a glide ratio of 8:1 would be able to glide to with altitude to spare?

Just exactly what magic or superman skills would this " safe " pilot have that would trump the ordinary pilot in the airplane that could glide to the airport?<

Chuck really dont want to get very involved in all this :-) so just a couple of warnings.

Realistically there is always a danger of trying to make a runway or distant place in any plane. Why ? because it focuses the mind on one point.
I was always taught in life to always have an "out" In a forced landing situation that to me means having a number of options and being able to take another option if you realise that one door or landing spot is not going to work for you.

There are many factors which will determine whether you get to a distant chosen landing site one being wind or groundspeed which can change on your way down. Flying in moving air we also have to consider rising or falling pockets of air and how that will effect your chosen profile.

The success of a forced landing will depend on skill and a certain amount of luck but also a quick mind in determining that something is not working and being able to change tack and take somewhere else which might mean a crosswind component or even tailwind.

Taking somewhere else might be somewhere which is not ideal and may take out a hedge or damage the undercarriage but at least you keep the thing flying to the ground.

A little tip worth trying for extending a glide very low level is to dip the nose to increase speed and get into ground effect. I can remember many moons ago being with an examiner in a forced practice landing. He told me that no way was i going to make the runway. I dipped the nose increased speed levelled in ground effect and we sailed along like a hovercraft to the runway. it does work why? havent a clue but worth trying in a practice situation.

:-) take care all

Pace

[SNS3Guppy]

I dipped the nose increased speed levelled in ground effect and we sailed along like a hovercraft to the runway. it does work why? havent a clue but worth trying in a practice situation.


Ground effect? Reduction of induced drag. Formerly known as T-effect.

[Pace]

SNS3Guppy

>Ground effect? Reduction of induced drag. Formerly known as T-effect<

Thanks for that :-)

Pace

[Chuck Ellsworth]

We can beat this subject to death forever and put forward as many arguments as there are stars in the sky.

However for someone like myself who is just a simple minded aircraft operator if I am to be faced with an engine failure at any altitude I'll take the aircraft with the best glide ratio every time.

The very worst scenario I can imagine flying a machine like that is having to wait a little longer for a safe landing rather than having to be super pilot with only a few seconds to display my exceptional skills just before I smack into the trees.

By the way how many of you here have used T effect to increase range during long over ocean flights?....... I have. :ok:

As long as we are sharing flying experiences what was your longest flight as a pilot flying the thing, mine was 19 hours and 10 minutes. :E

[Piper_Driver]

If I had an engine failure I would prefer an aircraft with the lowest stall speed and the lowest sink rate. A great glide ratio doesn't help a lot if that glide ratio is achieved at 120 knots. An aircraft with a low stall speed and sink rate will usually fare better in an off-field landing. It will also be capable of forced landings in smaller places. Just my opinion.

[SNS3Guppy]

By the way how many of you here have used T effect to increase range during long over ocean flights?....... I have.


Aha! I KNEW there would be someone here old enough to remember when it was T-effect.

As long as we are sharing flying experiences what was your longest flight as a pilot flying the thing, mine was 19 hours and 10 minutes.


Eleven hours and some change...but that's too long. Three hours is a lot better. We do eight hour legs all the time, and back to back legs with a tech fuel stop in between...but that's where a light airplane shines...not enough reach to go those kinds of distances. One to three hours is a lot better for me.

Going a long stretch like that gives a lot more meaning to the thought of someone like Lindbergh doing his 33 and a half hour flight...alone. That's a long time to not stand up and go visit the gentleman's room.

If I had an engine failure I would prefer an aircraft with the lowest stall speed and the lowest sink rate. A great glide ratio doesn't help a lot if that glide ratio is achieved at 120 knots. An aircraft with a low stall speed and sink rate will usually fare better in an off-field landing.


Touching down with minimum vertical speed is essential for an off field landing...but that's really nothing to do with glide ratio. Let's face it, even the space shuttle manages to land without winding up like a pancake, and it doesn't exactly have a stellar glide (just starts a little higher than most). Arresting the descent rate to land, with or without power...is just another landing. If you think about it, it's the same thing you do on every landing. Even in the 747, we land power-off...it's no different than landing a piper cub.

Sooooo...it's not the descent rate in the glide that determines how you'll touch down...that's just a matter of the distance you'll glide.

So far as the descent rate, most students are never taught that two basic glide speeds apply; one is the "best glide" speed, which is essentially what we're talking about in this thread. That's the speed at which the aircraft moves forward the farthest distance for a given amount of altitude lost. There's another equally important speed to consider, however, and that's minimum sink. Minimum sink speed provides the slowest descent rate, or more practically, the longest time aloft. It's found at a slower speed than best glide, and roughly speaking approximates the sea level best angle of climb speed for most light airplanes.

Best glide approximates the sea level best rate of climb speed. The speeds don't exactly coincide, of course (best angle and best rate are functions of available power--that's engine power for some--and change with altitude as available power and propeller efficiency change), but close enough.

Minimum sink is the speed to use when you want to stay aloft as long as possible, to troubleshoot a problem, communicate a position, etc. When stretching a glide as far as possible isn't important (it isn't if your landing site is below you), minimum sink may be just what you need to have time to prepare for the landing.

When you get to the bottom of the glide, of course, it won't matter what speed you used in the descent so far as the angle and descent rate...only that you arrest it (flare) to land.

[dont overfil]

How about one of the worst in GA. I remember my instructor inviting me to try a practice forced landing in a loaded Cherokee Six. From 3000ft the touchdown zone was inder the nose! A very capable airoplane with the engine running.
DO.

[Pace]

>?As long as we are sharing flying experiences what was your longest flight as a pilot flying the thing, mine was 19 hours and 10 minutes. <

Chuck my longest flight was a couple of months ago flying a Citation as Captain Florida to South Africa via Goose bay, Iceland direct, Prestwick (Scotland) Santander (Spain) Then down through Morocco, Algeria. across Nigeria to a little island on the Equator called Sao Tome and on down to South Africa.

This Citation was an S2 with a fuel capacity of 5800 ibs and 1500 nm range with reserves.

Diciest leg was to Sao Tome 400 miles off the Africa coast with not enough reserves to come back after the Nigerians refused to let us go high.

Total flight time 35 hrs at usually FL390 but with fuel stops and overnights.

But then again mine was in a Jet not like you brave guys in singles

Pace

[Chuck Ellsworth]

Chuck my longest flight was a couple of months ago flying a Citation as Captain Florida to South Africa via Goose bay, Iceland direct, Prestwick (Scotland) Santander (Spain) Then down through Morocco, Algeria. across Nigeria to a little island on the Equator called Sao Tome and on down to South Africa.

I have flown over Sao Tome but never landed there. But by longest flight I meant non stop without landing. .:)



But then again mine was in a Jet not like you brave guys in singles

There is no way on earth you could tempt me to ferry a single engine airplane on over water routes.....period...because I'm a coward.:E


Diciest leg was to Sao Tome 400 miles off the Africa coast with not enough reserves to come back after the Nigerians refused to let us go high.


AAhhh Africa, you just gotta love it.

I would love to share some of my more interesting experiences flying in Africa but I can get enough flack here just making comments about flying generally. :E

Pace

[Pace]

>I have flown over Sao Tome but never landed there. But by longest flight I meant non stop without landing. .<

Chuck what were you flying with that endurance ? it must have been tanked.

I have some nice shots of Sao Tome but cannot see how to add them here without linking to a site where they are held? They are on my computer.

A few of the airfields we used in Africa were over 5000 feet up still with temperatures in +35 deg thank god the runways were huge :-) cant remember the book rotation speeds

Pace

[Chuck Ellsworth]

Chuck what were you flying with that endurance ? it must have been tanked.


One of these, they can fly for around 23 hours when the fuel tanks are full.

http://i43.photobucket.com/albums/e353/ChuckEllsworth/Africanriver.jpg

That picture was taken in Senegal on our way from Toulouse France to Santiago Chile in 1998.

My 19 hour and 10 minute non stop flight was in the Canadian Arctic in 1968.

You must forgive me for being a little brain damaged but it really isn't my fault because I am a victim of aviation. :E