High accident rates in light twins an alternative?
 

We all know that the accident rate for light twins is attrocious with an engine failure.

Infact I believe you are more likely to survive a single engine failure and the subsequent forced landing than an engine failure in a twin.

Most light twins at best at grosse weight on a standard day are hard pushed to climb at 200 fpm and those figures are achieved on new aircraft with new engines, not old hanger rash aircraft, covered in flies with tired old engines.

With the second engine comes more options and with more options comes more opportunities for making a mistake.

I appreciate the high accident rate is partially due to the fact that most private pilots cannot afford to fly light twins and as such are not current enough to cope.

But where does the training figure in this high level of accidents.
We are taught to act in a particular way to an engine failure and have it drummed into us to such an extent that we go into mental autopilot and with the aircraft cleaned up go for blue line and a climb.

I have had three engine failures in my time. Two partial one full. One was at grosse and at 200 feet in the climbout. The aircraft was shaking badly but the engine was still producing some power. I elected to keep it going as even with some power I realised that I was not going to climb at all if I shut it down. I had one hand on the prop lever ready to pull it if there was a bang and then once up at a 1000 feet shut the engine down. The cause was three Sheared rocker shafts.

Another alternative was put to me by an ex fighter pilot for light twins and may be an option to add in certain circumstances.

While light twins are happy to fly along in level cruise with one shut down all day they are pathetic at best at blue line climbing. You only need a gusty day with downdrafts a desperation and fix on climbing and it is only too easy to get below blue line, get further crossed up, add further drag and loose the plot.

Once in the air an aircraft does not know that it is at 300 feet or 1000 feet and mayb in certain situations it might be better to go for level flight at 300 feet rather than the drummed in climb. Most airfields are not enclosed by high terrain and usually have a gentle turn route through where you can maintain level flight at your 300 or 500 feet. Once trimmed for level flight and at single engine cruise speeds step climb the twin in gentle increments using the trim. As the cruise speed bleeds off level again and repeat until you have sufficient hight to return or land at another airfield.

ThIs does work and while not suitable for all situations it is another option to consider if you get into a mess.
It is certainly worth trying in training with a safety pilot/ instructor and at altitude.

Pace

Blue line is the best climb speed on one engine. How is climbing, however slowley, better than maintaining altitude?

>Blue line is the best climb speed on one engine. How is climbing, however slowley, better than maintaining altitude?<

Because you may not be climbing at all at blue line and without speed your margins are smaller and it is easier to get below blue line with all the horrors of increased drag and a dramatically worsening situation which shows up in the appalling twin accident rates with one engine out.

But I am NOT putting this forward as a replacement to blue line climb but an extra alternative in certain situations. Go try it in a safe situation and make your own mind up.

Pace

I do see your point Pace, but the physics don't add up. It sounds a bit like the old "Getting it over the step" myth.

If you aren't climbing at blue line speed, i.e you are only just maintaining altitude, then you are using all the available power. If you don't have excess power to climb, you also don't have excess power to accelerate. If you DO have excess power to accelerate, you are always going to ALSO have excess power to climb.

What you seem to be getting at is keeping some extra margin over blue-line to alow for gusts etc. Fine- but holding a constant speed just above blue-line is going to be more efficient and give you a better net flight path than the "saw tooth" flight path you seem to advocate.

Unfortunatley there are no free lunches in physics- either the power is there or it isn't!

Interesting question - are there any hard statistics for this?

One way of solving the asymmetric problem is to close all the throttles! Ok you become a glider then but at least you are under control!

One thing the BA777 at LHR proved is that if you are going to crash then keep the wings level and don 't stall!

Your question only considers the take off situation. There are other occasions where it's nice to have two engines - flight over water or inhospitable terrain and/or night or IMC!

Reminds me of the definition of the ideal a/c when the engineer taps the captain on the shoulder to tell him "We've lost number 4" - the Captain replies "Which side?"

Ok yes light twins can be challenging but on balance I would rather have another engine. There are also aspects such as having 2 alternators and 2 vacuum pumps which mean more redundancy.

It would be interesting to know how many accidents have been prevented because the type was a light twin and not a single.

>If you aren't climbing at blue line speed, i.e you are only just maintaining altitude, then you are using all the available power. If you don't have excess power to climb, you also don't have excess power to accelerate. If you DO have excess power to accelerate, you are always going to ALSO have excess power to climb.

What you seem to be getting at is keeping some extra margin over blue-line to alow for gusts etc. Fine- but holding a constant speed just above blue-line is going to be more efficient and give you a better net flight path than the "saw tooth" flight path you seem to advocate.

Unfortunatley there are no free lunches in physics- either the power is there or it isn't!<

Wizofox

But it is Physics and there are no free lunches as you put it but the wrong way. With one engine out in a climb you have drag that you do not need to have. You have extra drag from a higher angle of attack on the wings and the slower you are the more rudder you will require to combat the yaw.
Its all a vicious circle.
By reducing the pitch you are reducing the drag and hence the aircraft will make the most of the available power and accelerate as it accelerates less rudder sticks out in the airstream.

On a hot day at Grosse weight your other engine might be there to carry you to the crash site. Before you make a forced landing this trick might work. As I Said go try it as its another option up your sleeve before taking to the trees.
And yes it is all about Physics so please do feel free to pull the Physics apart because it is for discussion.

Also remember we are always playing with available power and drag but we always have another source of extra power, an extra engine if you like and that is the kinetic energy inherant in the aircraft by using pitch or your
control column.

In a single engine aircraft with the engine out you have only that spare engine (kinetic energy) to maintain your speed to a forced landing. Instead of your throttle controlling your power. Your control column becomes your throttle and you are trading altitude to get that energy

Pace

flybob
 

B52 by any chance?

>Your question only considers the take off situation. There are other occasions where it's nice to have two engines - flight over water or inhospitable terrain and/or night or IMC!<

Fireblob

This is my point. You loose an engine in the cruise and its no major deal to shut it down and fly for miles on the remaining engine the plane does not know whether its at 4000 feet or 400 feet and behaves roughly the same.
But the same plane asked to climb? and you are in a totally different ball game.

Pace

RadicalRabit

No this is a serious point for discussion. I have over 2500 hrs in light twins alone and your welcome to my ATP numbers to a private E mail.

Pace

Whilst agreeing that the single engine performance of most light twins is very poor, I'd be interested to see your accident statistics backing up the initial premise - I'm usually quite on top of the accident reports and don't recall seeing many, if any, reports of losses of light twins following single engine failures.

G

All this talk about light twin accidents being 'attrocious' quite frankly is without hard facts.
In the USA, the accident rates for single and multi-engine airplanes are about the same.
However, what you don't hear about (nor reflected in statistics) are most of the multi-engine airplanes that have an engine failure enroute, and land just fine, thank you very much, at an airport.

Singles?
Usually make the news, simply because when the engine quits, you either find an airport (usually doesn't happen) or end up in the weeds somewhere.

The NTSB accident reports are there for all to read...and learn.

Of course, in other countries...could be totally different.

Mr. Boffin
 

No losses of aircraft (light twin) after OEI? Pretty bold statement, Sir. I know of two in my circle of aero alone. I'll check some more for you.(411: "atrocious" is in the eye of the beholder, your call isn't the Cessna 411? One would hope)

Airfoil

Pace,

Drag is made up of form drag, which increases as the square of velocity, and induced drag, which does indeed increase with angle of attack.

This is where we come up with the drag curve, where drag is minimum at a particular speed/angle of attack, and increases with EITHER an increase OR decrase in speed or angle of attack.

Vyse ("blue line" speed) is speed for maximum excess thrust on one engine, but is very close to the minimum drag speed. You are correct that drag from control inputs are a factor, but are included in the flight test data to determine Vyse.

Yes, but if you reduce "pitch" (I think you mean angle of attack- there is a difference) before you accelerate, you also reduce lift. If you were only maintaining height at Vyse, you are now descending. Sure you'll accelerate, but, as I said above, as you were at your minimum drag speed before, flying faster is only going to increase total drag and make things worse.

The blue radial is there for a reason. It really is the speed for best climb performance on one engine.I have a similar amount of light twin time as you (though a lot of years ago!) and I know that sometimes equates to "Not very much!!", but it is the best you are going to get. Fly any other speed, faster or slower, and you degrade the aircrafts climb performance.

I think I understand what he's saying. He's not saying that nosing over will find you some extra power you weren't making before, but rather assuming you've got a small but positive rate of climb, so you do have excess power available by definition. Therefore it is conceivable that you might be able to reduce your workload by trading a climb that really isn't getting you up very fast for a little extra airspeed so long as you're above the surrounding terrain. Obviously, if you weren't climbing a Vyse, this would go right out the window.

However, I think the improvement in handling qualities would vary from aircraft to aircraft depending upon how wide the spread between Vmca and Vyse is and the few extra knots you gain might not be worth it.

I remember reading a very intersting article in one of the big General aviation "Comic books" when I was going my initial ME rating, written by one of the well knwon gus, whos name escapes me now.

Up to that point I had read all the material the good people at Jepps and the FAA had written on dealing with Engine failures shortly after takeoff, as well as my instructor. Essentially, get it cleaned up, and climb away at Blue Line.

The author of this article stated that Comair, who started out in life operating only light twins such as the Navajo had suffered serious accidents as a consequence of Pilots loosing an engine, and tring to climb away at blue line, but due to the face that they were nearly always at MAUW and in hot conditions or high locations, had resulted in speed decaying and loss of control in flight at low levels.

Their revised policy was this:

Engine Failure from 0ft-500ft, close throttles, land straight ahead.

500-1000ft Close throttles land ahead, with turns of up to 40 deg left or right

Above 1000ft Attempt to climb away at blue line.

The reasoning was that it was far more likely to go below VMC and violently loose control at low level resulting in a large smoking hole, then to have a more then likely survivable forced landing under control.

I only did about 15 hrs Multi Engine Piston and I fly Jets now, but I often wonder still, if I had found myself in that position would I have gone with conventional wisdom or the other option. Pardon my ignorance.

>Yes, but if you reduce "pitch" (I think you mean angle of attack- there is a difference) before you accelerate, you also reduce lift. If you were only maintaining height at Vyse, you are now descending. Sure you'll accelerate, but, as I said above, as you were at your minimum drag speed before, flying faster is only going to increase total drag and make things worse.

The blue radial is there for a reason. It really is the speed for best climb performance on one engine.I have a similar amount of light twin time as you (though a lot of years ago!) and I know that sometimes equates to "Not very much!!", but it is the best you are going to get. Fly any other speed, faster or slower, and you degrade the aircrafts climb performance<

Wizofox

Yes I do mean angle of attack :-) I can give you some figures off a Seneca Five. With an engine shut down and feathered it will cruise at 127 kts compared to 155 kts with both going and that is with a high cruise setting not max power which you would have trying to climb at blue line which is about 90 kts.

So we have a difference at a lower power setting of nearly 30 kts.
That difference is purely down to drag nothing more nothing less.

Faster air over the wings creates more lift meaning that you can reduce the angle of attack and hence the drag for a given amount of lift.

In the situation we are talking about where because of tired engines a bug splattered airframe, temps, weight etc where we have max power, blue line and no or negligable climb then yes as we reduce the angle of attack initially the aircraft will start a very slight descent. As the speed increases so does the lift meaning you can reduce the angle of attack even further and even further again as the speed continues to increase to a cruise single engine speed.

As I said do try it :-)

Pace

>The author of this article stated that Comair, who started out in life operating only light twins such as the Navajo had suffered serious accidents as a consequence of Pilots loosing an engine, and tring to climb away at blue line, but due to the face that they were nearly always at MAUW and in hot conditions or high locations, had resulted in speed decaying and loss of control in flight at low levels.<

Telstar

I agree Landing ahead is a last option and I am putting this forward as a further option which can keep you in the air rather than down in the trees. I have tried it and it does work.

If there were good twin accident statistics engine out I would shut up but they are attrocious and to me the training and options trained are not complete for light twins ONLY.

If anyone wants to argue the Pyschics feel free as I am purely opening up a discussion not trying to win points

I am not trying to reinvent the wheel but wonder whether the wheel was totally round in the first place regarding light twin training. The problem could be that historically light twins have been used to train for bigger stuff that climbs at 1000 fpm engine out and the training doesnt look at the light twin on its own.

Pace

AirfoilMod - I don't dispute that accidents must occur since I don't manage to read every accident report in the world and I'd be amazed if there aren't some SEI related accidents. But are they really significant in the global scheme of things - that is compared to other accident causes, or for that matter in terms of engine failures causing accidents when they do occur? I'm happy to be convinced, but I've not seen the stats to do so.

G

By any chance do you mean that L= CL*1/2 rho*V>2? Cause it does.

If what you said above were true, then the faster you went, the less total drag you'd produce, and the aircraft would just keep accelerating until it approached the speed of light! Congratulations, you've just invented perpetual motion and solved the universes energy crisis!!

Induced drag is one side of the story. On a typical light aircraft it reduces to near its minimum value at about 5deg A of A, and peaks at CLmax, which is to say stalling angle.

But as speed increases, so does form drag.

Tell me, if you put your hand out the window of your Seneca at 127kts as opposed to 90 kts, at which speed would you feel the most drag? That's called form drag which, as I explained, increases with velocity. Do you dispute this?

So, you have one form of drag that INCREASES with speed, and one that REDUCES (though, after a while, only by a little). At some point, the sum of these two values is at a minimum, and that is Dmin, which is very close to Vyse.

Hav a look here:- http://selair.selkirk.bc.ca/aerodyna...rag/Page9.html

Your Seneca may be able to maintain a Tas of 127 at altitude, but it won't sustain a climb at that speed. The maximum sustained rate of climb occurs at a particular speed, and the nice guys at Piper even put a blue radial on your ASI to let you know what it is.

By any chance do you mean that L= CL*1/2 rho*V>2? Cause it does.

>If what you said above were true, then the faster you went, the less total drag you'd produce, and the aircraft would just keep accelerating until it approached the speed of light! Congratulations, you've just invented perpetual motion and solved the universes energy crisis!!

Induced drag is one side of the story. On a typical light aircraft it reduces to near its minimum value at about 5deg A of A, and peaks at CLmax, which is to say stalling angle.<

NO because at the end of the day the airframe is pushing through air and there will always be a terminal velocity for given power. Hence even a sky diver will hit a terminal velocity. As you know the higher in the atmosphere the faster you go.

>If the BEST rate of climb is zero, flying any other speed produces a descent.<

Yes if you have 90 kts and blue line and you are only staying level any reduction in the angle of attack will result in an initial decent and an increase in airspeed as Kinetic energy comes into play and assists the energy produced from the engine. But then as airspeed increases the lift increases for a reduced angle of attack and the descent rate will reduce until as the airspeed increases further you will finally achieve level flight at single engine cruise speed.


The same as pushing a wooden spoon through custard and water and a wooden spoon isnt a wing and neither is the sky diver.

I am fully aware of other forms of drag and your theories on how blue line is calculated for single engine climb. But as you know only too well at best lighttwins do not climb very well and at worst dont at all, You are also very close in speed to where if you get below blue line the drag increases dramatically and that is the killer.



Pace

Pace:

Sorry but the Wiz is right on this one (but never mind the man behind the curtain! - sorry, couldn't resist). When you do flight test to determine Vy, you do climb testing at various airspeeds and construct the total drag curve shown in the reference he cited. The bottom of that curve is Vy and it gets published in the books. Vyse is determined in a similar manner with one engine out which automatically takes into account the added drag of using rudder to counteract the yaw moment. So there's no way to reduce drag by deviating from the blueline speed. Hence, if you're not able to climb at Vyse, reducing your AOA is going to result in a loss in altitude that you will not be able to regain. Not a good situation.

However, what I think your fighter jock friend was getting at is that for many airplanes, the bottom of that curve is rather flat. That means that if you have a little excess power available (i.e. a positive rate of climb at Vyse), you might be able to gain a significant amount of airspeed if you level off. But this effect can - and probably does - vary quite a bit between aircraft. On some it might work great. On others, it might not be worth it. Therefore it's not something you could teach folks to do unless you were willing to submit to requiring a type rating each aircraft.

Thanks Gr8, There"s no place like home!!

Pace,

One big difference between Skydivers (1200 jumps and an AFF rating, just by the way!!) and aeroplanes is that skydivers don't have engines!! Aeroplanes don't have "Terminal velocities". They accelerate until the total drag (which, we've established, INCREASES as speed increases at any speed above Dmin) is equal to the thrust.

I think you may be acknowledging that the best performance is indeed achieved at Vyse. What you then suggest, i.e that the problem is that at any speed below that, drag increases, is totally valid. If you have excess performance, indeed it may be wise to use it to climb at a higher speed, thus increasing your margins over the bottom of the drag curve. This will, however, lead to a reduced climb rate. If the terrain makes this acceptable, then it may be fine as a technique.

You did, however, indicate that you believe the aircrafts total drag reduced and performance increased at speeds in excess of Vyse and, I think I've shown, this is simply false.

Wizofox

>One big difference between Skydivers (1200 jumps and an AFF rating, just by the way!!) and aeroplanes is that skydivers don't have engines!! Aeroplanes don't have "Terminal velocities <

Firstly aeroplanes most certainly DO have terminal velocities!!! and sky divers most certainly DO have engines :-) Ok not in the conventional sense but in the Kinetic energy they are using returning earthbound and which was created hoisting them skybound. In the same sense a glider has an engine in its Kinetic energy which was created pulling it skybound and which is on tap to the glider pilot through the joystick earthbound. the joystick is his throttle if you like.

No again :-) Put in simple terms as I am a practical sort of pilot and not a mathematician what do you do if you are holding blue line, you are at 400 to 500 feet and rather than getting a climb your VSI and altitude are going down?

You either panic as do many low time twin pilots and pull back trying to get a climb and go into coffin corner or you put it down hoping you dont take out trees or buildings in the process.

Take my word for it there are many situations as above where the aircraft ends up as a hole in the ground. Hence the bad engine out record of twins.

You also know that while many twins really struggle especially on hot days at grosse weight and blue line does not work in giving you the desired climb or even maintaining altitude.

So you have two choices you either continue trying to get a climb and end up in coffin corner with the usual stall /spin hole in the ground or you close both engines use the kenetic energy( which incidentely was created by the aircraft engines dragging the plane mass to altitude) and become a glider to a forced landing. (using the inherant kinetic energy to control your speed on the way down ie your spare engine as with the Skydiver) :-)

Your other option is to try out what I have said on your next flight. Mathematics or armchair pilot discussions aside it does work. I have seen and experienced the reality of this with my own eyes.

Then when you have tried it come back and explain why.
As they say the proof of the pudding is in the eating

You are missing something in the science or the mathematics here but the clue has to be in the fact that light twins will happily cruise all day on one engine at 127 kts but will not happily climb at blue line in all conditions and that is a practical answer.

Pace

The rationale seems to be that even if your rate of climb at Vyse is pitiful, with no terrain to worry about it may be better to accept even half of pitiful in return for the better control that a speed above Vyse offers, since fatalities are typically associated with loss of control rather than CFIT. Since the curve is relatively flat, you may manage quite a speed increment without losing all your climb capability.

I can't see the point in step climbing. Surely a sustained, trimmed, shallow climb is preferable, and will return the same or better average RoC without having to flirt with Vyse from time to time?

>I can't see the point in step climbing. Surely a sustained, trimmed, shallow climb is preferable, and will return the same or better average RoC without having to flirt with Vyse from time to time?<

We use that technique all the time in underpowered citation jets at high altitudes. It is again using your jet engine power which is insufficient to maintain an adequate climb and subsidising that power by adding the kinetic energy created in level flight.

While in a citation 2 you may struggle from FL350 and pan out trying to achieve FL370 at a given weight and conditions. You can get up there by allowing the aircraft to accelerate and then use the jet power plus the kinetic energy to give you the climb to FL370

Pace

So let's all call for an abort after V1, overboost our engines for the sake of getting more runway left if we need an abort, instead of using the shameful derates/flex, and tell the crew to change seats when hanging by the props because of the rotational direction...

Really?

Nice one SSG v4.0... I can't wait for V5.0
---
Another beer Pace?

PK-KAR

PK-KAR >Another beer Pace?<

Is it my round or yours ? :-)

Actually I am getting quite fond of him popping in in different guises :-)

Pace

Sorry mate, I miscounted...
It's v7.0 now... just waiting for v8.0...

At the rate this is going, I'd have liver failure pretty soon!

Oh whaddaheck... Here's another round of beer...

A few ill-conceived ideas floating around in this thread ..

(a) AEO/OEI, the climb performance graph is something of an upturned teacup profile .. with the AEO picture sitting a long way above the OEI

(b) the actual numbers will depend on the aircraft, configuration, atmospherics, etc

(c) regardless of the numbers, best climb performance is somewheres in the middle .. not at the ends of the graph

(d) typically, in a light twin other than at low weight and Hp/OAT, this OEI best climb performance will be modest .. or negative (ie a descent)

(e) if the aircraft flies slower/faster (presuming same thrust) it will be at a reduced climb/increased descent as appropriate .. you can't make something from nothing

(f) blue line is for one set of conditions and may not be appropriate for the actual conditions (including aircraft in-service deterioration) but it's probably a good place to start unless you have the flight test info to start with a different speed

(g) the problem of letting speed decay trying to chase mythical climb performance ... is one of flight management discipline and airmanship and has a predictable outcome in most cases ...


So far as ssg is concerned .. we will continue to remove posters who show an uncanny resemblance to him ... however, each new incarnation takes a little while to suss out. If it provides a modicum of amusement for the remainder of the folk, so be it.

Pace,

Last post for me as you've proven you're not good at listening.

If, in the above situation you now lower the nose to accelerate (assuming you were at the correct Vyse at the time), your descent will increase and will stay that way. Thus your hole in the grond will be nearer and deeper.

As to "Step climbing" a Citation, if you didn't have the excess thrust to get to 370 in the first place, you won't have the thrust to stay there.

Find me one authioratative text that refers to an aircrafts level airspeed as a "Terminal velocity."

As to being an "armchair pilot", MY armchair is located at the front left of a Boeing 777!

>If, in the above situation you now lower the nose to accelerate (assuming >you were at the correct Vyse at the time), your descent will increase and will stay that way. Thus your hole in the grond will be nearer and deeper.<

So what you are saying is that even at 2000 feet and a blue line climb with no climb. If you reduce the AOA and increase speed you will descend all the way to the ground from 2000 feet?

>As to "Step climbing" a Citation, if you didn't have the excess thrust to get to 370 in the first place, you won't have the thrust to stay there.<

Again step climbing is used by many citation pilots where the climb rate is so low that the only way you can stop it going on the back of the drag curve is to allow the speed to increase, lower the angle of attack and use the kinetic energy to assist that last bit of climb. As you level and the aircraft accelerates and angle of attack reduces so does the drag making the available thrust sufficient.
At high level the gap between the Ias and stall is small and yes there will be a level where to maintain that gap you would start sinking.
It is not just about available thrust its also about AOA and drag.

>Find me one authioratative text that refers to an aircrafts level airspeed as a "Terminal velocity."<

Every object will have a terminal velocity

Wizofox

Rather than point scoring over each other I would rather leave it with you and beg to differ. You will not change my opinions and I will not change yours.
All I will say is that the accident rate is very poor for engine failures on Light twins and that is an unacceptable state. So something has to be wrong somewhere?

All the best

Pace

This sort of 'statistic' surfaces from time to time...

The fact is that following engine failure in a twin, providing the subsequent landing is safe, there will be no formal 'publicity'; the event is non-reportable and will not be investigated. Thus the numbers are slewed - all the published reports you see relating to twins with one engine out are accident reports, because something has gone wrong.

The assertions above are simply rubbish. Even if you wanted to prove them, you couldn't, because there are no statistics to help you. Many engine failures occur in light twins, and end in safe landings on proper runways.

>The fact is that following engine failure in a twin, providing the subsequent landing is safe, there will be no formal 'publicity'; the event is non-reportable and will not be investigated. Thus the numbers are slewed - all the published reports you see relating to twins with one engine out are accident reports, because something has gone wrong.

The assertions above are simply rubbish. Even if you wanted to prove them, you couldn't, because there are no statistics to help you. Many engine failures occur in light twins, and end in safe landings on proper runways.<

FrontLefthamster

You may have a valid point and it would be nice to see those statistics and how they arrive at them?

But fair dues a pilot of a light twin always has the option of closing both down and treating it as a forced landing.

That is the difference the second engine gives you more options than in a single my suggestion was another further option to have up your sleeve.
If that still doesnt work close them both and take your chances with what lies ahead. Your not loosing anything and it does work science or no science.

Pace

Pace, the difference is that I am stating facts, not opinion.

Best rate of climb, single engine is just that. Minimum drag is just that. Maximum altitude is just that. You claim to somehow magically be able to make an aircraft climb at BETTER than BEST rate of climb by achieving LESS than MINIMUM drag, and climb to HIGHER than MAXIMUM altitude.If that's the case, Boeing needs to talk to you now!!

The problem is not so much the marginal rate of climb following an engine failure shortly after take off, but the failure of the pilot to take instantaneous corrective action including the feathering procedure. The flying schools teach an often inappropriate lengthy period of identification via various methods, and often critical seconds have gone by the time the pilot gets around to actually feathering the propeller.

A generic drill mouthed by the pilot may include identification of the failed engine by the direction of initial yaw (dead side - dead leg etc). Then a careful check of the engine instruments to confirm the cause of the initial yaw. Then a further confirmation takes place by slowly retarding the throttle of the suspect engine. All this time the colossal drag of the windmilling propeller is taking steady toll of airspeed and within literally seconds the airspeed has dropped 10-15 knots from the initial engine failure figure.

The fact is the feathering of the propeller must take place immediately after the engine failure is detected in order to stop the danger of speed decay. The risk of closing down the wrong engine must be balanced against the certain potentially fatal loss of airspeed that will occur unless the dead engine is feathered without delay. The act of closing the throttle of the suspect engine as a means of confirmation, raises the question of how fast do you close that throttle lever. It is generally accepted as a slow movement just in case the wrong throttle has been closed and you don't want to momentarily lose all power (wrong throttle pulled back and dead engine already dead equals a problem!).

A slow pull back of the suspect engine loses more precious seconds of windmilling drag and thus decaying airspeed. To competently handle an engine failure after take off at low altitude requires instantaneous correct feathering action without the luxury of "dicking around". This way, the danger envelope of windmilling drag is minimised to perhaps around 5-8 seconds. But to arbitarily state the pilot should deliberately close both throttles and crash straight ahead simply because the altitude is less than 500 feet when an engine fails, is shutting off all options that may have been available.

>Best rate of climb, single engine is just that. Minimum drag is just that. Maximum altitude is just that. You claim to somehow magically be able to make an aircraft climb at BETTER than BEST rate of climb by achieving LESS than MINIMUM drag, and climb to HIGHER than MAXIMUM altitude.If that's the case, Boeing needs to talk to you now!!<

Wizofox

Yes I appreciate best rate of climb single engine. I appreciate Minimum drag at best rate of climb BUT I am not talking about climbing at all or minimum drag in the climb.

The reason I am NOT is the very fact that even with new aircraft where the miserly 200fpm are achieved on standard days, Many light twins may be 20 years old, be covered in hanger rash, have tired engines and the temperatures may be above standard.

Most light twins quote 200 fpm as new test aircraft, some not even that. So the point is not to climb at all but even low level to go for a single engine cruise.

With any climb you are looking at an increase in angle of attack and with an increase in angle of attack you are looking at DRAG.

Remove that drag and as I stated as fact a seneca will accelerate to near 130kts on one engine in a level cruise. Push the nose over and that 130 would increase as the aircraft traded altitude for its inherant kinetic energy.

Drop below blue line and you are into coffin corner as the drag increases dramatically and that is where the margins are very small.
The guy who does everything right establishes blue line, has the aircraft clean and still has no climb or even a descent has two choices one is to close both throttles and glide to a landing ie using kinetic energy alone to control his speed to a landing or he can reduce the drag of a climb and set up a level cruise.

Its not Magic but pure fact that a light twin will cruise for hours happily with one shut down but will not climb happily with one shut down.

The step climb works on the fact that you are dipping into Kinetic energy to add to the available power from your engine and gain some altitude.
I will give an example from the seneca.
You have one engine running your speed in level flight is 127kts (fact) you are not going down but level. Now you pitch for a climb. You still have the power of that one engine which is constant but you trade some speed for extra climb. As you pitch up the drag increases and the aircraft is now climbing with the constant engine power plus the kinetic energy. What happens is the speed starts to decay but you get a greater climb rate than you would at blue line. Allow the speed to decay from 127 kts to say 105 kts and then pitch for level flight again maintaining altitude. Slowly the speed will increase. when you are back to 127 kts go through the process again.

All I am saying here is make the plane do what it can happily do ie fly level not climb. If you cannot see that I really do not know what to say Other than I will beg to differ with you these are facts not suppositions and I am happy to demonstrate to you any time. If I am right you pay for the flight if I am wrong I pick up the bill.

Pace

It can become 50fpm before you know it... if you're lucky... and that's before OEW revisions...
Whenever we got one engine out on take off, I have to rush back to the hotel and pick up clean underwear... not too often, but you know what I mean.

At 33C, we're often reduced, because otherwise, we'd be forced to do what Ssg does on N-1 at anywhere during the take off, abort... I refused a "symbolic" V1 for the ops... reduce the load thank you! The first time I saw that light twin do a near MTOW run after maintenance, the engine conked out and 3000m runway suddenly looked very short!!!!! (thanks to a former CASA/MDCA guy who advised we avoid MTOW citing reasons Pace mentioned).

For ref: It was a C402B, a DAMN OLD one... :}:yuk::ugh:

PK-KAR

Pace,

We are actually closer to agreement than you recognize, at least in terms of technique. Flying level at a higher speed rather than climbing slowly at Vyse may indeed have merit as a technique where terrain is not a factor.

What I am NOT willing to let you go on is some of your more outrageous errors when it comes to aerodynamics, as they have led you to make statements that work only in the magic kingdom.

Your statement:- and then say Shows that you neither appreciate or understand a fairly basic concept.

Minimum total drag occurs at a particular angle of attack, which, at a given weight, will correspond with a particular speed. Whether you climb, descend or stay level at that speed depends on how much power is applied. You continue to imply that accelerating , because it lowers the angle of attack reduces drag. It REDUCES induced drag whilst INCREASING form drag, thus INCREASING total drag. Minimum means minimun, anything else is an increase.

Vyse is not exactly Min drag, but it's close, as it takes into consideration things such as control drag. BUT it is the BEST RATE OF CLIMB SPEED and thus, by definition, any other speed has LESS rate of climb (Look BEST up in the dictionary!). If the BEST rate of climb is zero, flying any other speed produces a descent.

Go ahead and and fly level all day. As I said, it may be resnoble under some circumstances. Just don't imply you can somehow make an aircraft do BETTER than BEST!.

By the way, have another look at that chart that gave you 127kts cruise on one. TAS right? At what weight and what height? Work out what INDICATED speed that corresponds to, and get back to me!!

When I flew twins off a reasonable runway, I would get the old girl airborne let her accelerate to about Blue line +20 before putting the gear up and climbing away. I would be through 1000' AGL in no time. That way, if one quit prior to blueline +20 I didnt have to worry, I would just put her back down on the runway if I needed to and once the gear was up, I was gauranteed a climb with a healthy margin above blue line until about 1000' AGL where I could level out and asses the situation. My reason for flying like this was for the exact reason PACE asked the initial question. To keep a healthy speed above blue line!

Bear in mind, this option isnt advisable on a short runway!

OSOP