C150 vs C152 [Archive] - PPRuNe Forums

Pilot DAR

21st Oct 2008, 16:57

The 152 does have a few more horsepower than the 150, and often a somewhat more coarse pitch propeller, so a little faster cruise can be expected. In a 150, 2200 RPM is on the slow side for cruise power. 2400-2500 will get you better results, particularly if you are leaning. The mixture distribution is more even at 2450+-, than at engine speeds faster or slower.

70kts does sound a little slow though. It could be that the prop on the 150 is pitched to a very low blade angle, for better climb. There are also wing adjustment cams, whose position can slightly affect cruise speed. I presuppose that the engine maintence is adequate. The O-200 is a fine engine if well cared for, but low cylinder compression can be a problem, and it will reduce power output. The O-200 is very unhappy running on 100LL, and this was another reason for the change to the O-235, which was very happy on leaded fuel. The 80/87 of the "old" days ran very well in O-200's. Though 80/87 was permitted to contain lead, it rarely did, so lead fouling was not a problem in the O-200, until 80/87 was no longer available. When 80/87 became difficult to obtain, and 100/130 became the "norm", the O-200's suffered terribly.

The flaps are different between the types, not in the selector (the few 1977 150's had the same "preselect" flap control as the 152's), but in the angle. All 150's have 40 degrees of flaps available, all 152's have only 30 degrees. That last 10 degrees is very noticable for short field work. The problem is that the aircraft is easily able to land into a runway too short to takeoff later. It also makes full flap overshoots a little challenging, though contrary to what you will regularly read here, a 150 will safely climb away with full flaps. I think that Cessna changed their thinking to no longer optimize short field performance, and more tend toward simpler trainer type performance.

Another difference between the types is that most if not all 152's are 24 volt electrical system. The O-200 engine was not available with a 24 volt starter and alternator.

You can play around with getting on the step, but the affect is much less noticable on the 150/152, than on other types. It's not a bad Idea, but not a big help either.

I hope this helps, enjoy the 150

Pilot DAR

Pace

21st Oct 2008, 17:20

PilotDar

I can remember flying two 150s one had an 80 hp unit the other a 130 hp unit.

The one was like an old dog the other like a bat out of hell.

Pace

EchoMike

21st Oct 2008, 17:49

(Single paragraph caused by unresolved obscure browser problem.) 150 is 100 hp, if older cylinders fitted, timing is retarded to 24 degrees BTDC, you'll lose about 3 or 4 hp which you really won't notice anyway. Later cylinders timing is 28 degrees BTDC, the AD note doesn't apply, you get all 100 (thundering) horsepower. 152 is Lycoming of 108 or 110 hp (depends on year), 28 volt electrics, flaps limited to 30 degrees. 70 lbs increase in MTOW. Overall performance is about the same between 150 and 152. Your 70 to 75 kts airspeed seems slow, go ahead and flog it a little, the O-200 likes to be run hard, 75% power all day long and it will lap it up. Variations: base engine is 100 hp O-200 on ALL USA 150s (there's no 80 hp option), 108/110 on all 152s. Rheims 150 (FR150) sometimes had a somewhat problematic Rolls-Royce O-240 of 135 hp (under license from Continental), few parts available any more, and they're expensive if you can find them. STCs for the 150 include 150, 160 and even 180 HP Lycomings, for the 152, there is a "Sparrow Hawk" conversion (prop & pistons) which takes it to 125 hp. If your airplane is really only going 70-75 Kts at cruise, either open the throttle some more or look for problems, cruise at 2,500 ft MSL on a 150 is right about 100 to 105 mph, or 90 KIAS. Check the ASI calibration, read the POH for 75% power at different altitudes. Best Regards, Echo Mike N150EM

Pilot DAR

21st Oct 2008, 19:25

EchoMike is right on....

SFCC

21st Oct 2008, 20:23

EchoMike is indeed right on.
cpl4hire is talking utter bohoolicks. Just like most other people that have never spent enough time reading their books.:ugh:

Put1992

21st Oct 2008, 20:36

Apart from the ASI being in MPH as opposed to knots (you've still got the inner scale), and the flap selection being a bit different (it's more easier doing circuits in the 152 than the 150) there isn't a considerable difference. 152's with long range tanks obviously make a bit of a change when your taking flight planning into consideration.

Cheers

First_Principal

22nd Oct 2008, 09:15

I get 85-90 KIAS out of my 150 but tend to run it at 2400 rpm or a little above most of the time. Rarely would I use much less than this, so I'm with the others, try pushing it a bit more - if you're in doubt it may be worth getting the RPM gauge checked out with one of those handheld digital strobe meters, some gauges can be out by 100 rpm or more without you being particularly aware of it. So while 2200 is quite low (for a 150) already you could find it's actually running at 2100 or even less. I wonder what it indicates when you do a static check? If you look it up for the particular prop you have etc you should be able to get a reasonably accurate idea of your expected static RPM and see if it differs much from that.

FWIW the 152 I fly doesn't perhaps appear to work quite as hard as the 150 but in practice there's not an enormous difference in route times between them.

Pace

22nd Oct 2008, 09:42

For all you could ever want to know on the Cessna 150 series follow this link

Cessna 150 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Cessna_150)

Pace

Okavango

22nd Oct 2008, 18:21

Thanks to all who provided advice, your notes gave me confidence to set off on my qualifying cross country which I completed today. I tried the higher power setting and performance was just as you describe - it seemed to be just shy of 100 mph at 2400rpm in cruise. I've let the school instructors know as seemingly they had been flying it with power settings as per a C152.

Final 3 Greens

22nd Oct 2008, 19:25

Okavango

The RR/Continental engine in the 150 can collect carb ice more than the Lycoming in the 152.

You may wish to do your FREDA checks very regularly and consider leaving the carb heat on for 30-60 seconds.

If the engine runs rough, keep the carb heat on, it will clear the ice causing the rough running.

Of course discuss the above with your instructor.

Lost man standing

22nd Oct 2008, 20:05

Sorry, have to challenge Pilot DAR on the full-flap go around in a Cessna 150.

It might be that technically, this is possible, although I have never heard of anyone managing it. What it is not is safe! I have tried and failed myself, and know of at least one experienced instructor ending up in a field due to a fuse blowing on the flaps during a PFL. Unable to retract the aircraft would not climb away.

Pilot DAR

22nd Oct 2008, 20:46

With due respect to the lost man standing, I cannot agree that the full flap go around is not safely possible. I agree that they require care, but if proper flying is executed, it can be safely done. I have done it at night, when my flap fuse blew (changing it in the dark while going around, seemed like a bad idea). I have also purposefully taken off with full flaps a number of times with no difficulty. I certainly am not suggesting others do this, but for those who would like to flame me, I will draw attention to the fact that the flight manual contains recommended flap settings, but no prohibited flap settings, I also own the plane, and planned well ahead (large frozen lake - no obstructions).

A full flap overshoot is a required design compliance element, and I am required to demonstrate that the aircraft can still do it after some aerodynamic modifications (installation of wheel skis). The text of the standard is as follows:

3.596.
(c) Balked landing conditions. The steady angle of climb at sea level shall be at least 1:30 with:
(1) Takeoff power on all engines,
(2) Landing gear extended,
(3) Wing flaps in the landing position.
If rapid retraction is possible with safety without loss of altitude and without requiring sudden changes of angle of attack or exceptional skill on the part of the pilot, wing flaps may be retracted.

If I can't make the plane safely do this, I do not approve the modification. My personal criteria is that rapid retraction is not possible, if the fuse could have just blown. It gets flown away full flaps. I do not retract the flaps at all, until I have seen a sustained climb. I'm not saying it's a great climb, but it will do it. I've even had mechanical Cessna flaps fail down! (broken flap track on floatplane) By the way, a 1:30 climb is pathetic.

There are other operations in which flap settings exceeding the flight manual recommended settings will produce results better that the recommended flap settings. Climb is not one of those.

I shall take the opportunity to glance off the comment about instructors as a measure of skill in piloting: There are good pilots, not so good pilots, and instructors. Instructors can be in either of the former catagories. I do not consider an aspect of an aircraft's handling or performance good or bad based upon the opinion expressed by an instructor, just because they are an instructor. I will listen to the opinion of a pilot's license holder with a lot of time on type, and experience on similar types. Instructors are a vitally important element of aviation, but not always the final stop for knowledge and wisdom.

There is no reason that you, as a pilot under instruction, or solo, when way up high, where it is extra safe, would not try a full flap go around, just to see how the plane flies that way. (hint, it's slow flight at full power)Things fail.... You may as well practice!

I hope that reassures you a little.

Pilot DAR

Lost man standing

22nd Oct 2008, 23:15

Either you misread my post, or your definition of "safe" is somewhat different from mine. Assuming that the requirements were the same when the 150 was designed as they are now and it therefore complies, it can barely do so and only when in good condition. It certainly isn't easy to achieve any climb at all in a typical, battered, abused airframe with 40° flap. It is therefore not a good idea to suggest it is safe in a forum frequented by pilots of a variety of experience levels.

An instructor who has run the flying school which owns the aircraft for several years is probably about as good at flying a 150 as anyone. If he can't fly away in an area with no especially steep terrain, I reckon it isn't a safe manoeuvre!

Mark1234

23rd Oct 2008, 00:17

I suspect the issue may well be to do with how slow one is willing to fly - in this day and age we are taught to fly with such fear of the edge of the performance envelope that most pilots aren't willing to get within a country mile of the low speed end of things. You'd have to be going pretty slow to climb with full flap.

PilotDAR what sort of airspeed are you using for a full flap climb?

Incidentally, I was given to believe (again by a crusty old instructor type) that the reason for the 30degree flap limit on later aircraft was to permit increased MTOW while still allowing the full flap climb requirements to be met.

Practically I've noticed little difference between the 150/152, other than I can't turn final in my customary (very high) position in the 152 without sailing past the numbers at a great height... that last 10degrees makes a big difference.

Pilot DAR

23rd Oct 2008, 03:15

The information given to Mark1234 sounds the same as that I have heard, the 152 has a lesser flap limit due to less than adequate climb performance at gross weight with 40 degrees of flap. The 152 seems to have a propeller optimized more for cruise than climb. I have taken off 152's from runways where they struggled out where a 150 in the same runway had no difficulty, in otherwise very similar operating conditions. I have not done a detailed comparison of performance data though.

The airspeed required to obtain a climb in a 150 with full flaps will be very close to stall warning speed.

"Safe" is a very challenging thing to measure. Hence my pasting in the wording of the standard which would be applied to the 150, both back then, and now. The current standard's wording for the same requirement is:

523.77 Balked Landing

(a) [Each normal, utility, and aerobatic category reciprocating engine-powered aeroplane of 6,000 pounds or less maximum weight must be able to maintain a steady gradient of climb at sea level of at least 3.3 percent with:
(1) [Takeoff power on each engine;
(2) [The landing gear extended;
(3) [ The wing flaps in the landing position, except that if the flaps may safely be retracted in two seconds or less without loss of altitude and without sudden changes of angle of attack, they may be retracted; and
[(4) A climb speed equal to VREF, as defined in 523.73(a) (http://www.tc.gc.ca/aviation/regserv/carac/CARS/cars/523/english/523sa-be.htm#523_73_a).

Vref would be about 1.3 times stalling speed in that configuration. Still pretty slow. The reference to skill still applies by a reference from a preceding paragraph. Thus the reference to airspeed for climb is the only difference between the two standards.

The earlier (previous post's) standard (CAR3) is the wording which would apply to the designs of both the 150 and the 152, though at the time that the 152 design was being validated by Cessna the newer wording would have been available (and for certain Cessna would know it well) so Cessna would have have compliance with the newer standard in their mind too.

The challenge is deciding what "without requiring.... exceptional skill on the part of the pilot" really means. That is where we are measuring "safe" as objectively as possible. The later standard does add one more condition, which reduces the demonstration pilot's opportunity to use his/her exceptional skill so as to show "safe" compliance of the aircraft. It is understood that the demonstration pilot's recent experience performing such flying, might give that pilot exceptional skills in that aircraft type. This is to be discounted by the pilot who performs the certification evaluation flying.

So how sloppy is that pilot to be to be fair to both sides? I know that I'm doing it very fairly when I pilot an aircraft type which I've never flown before, and show compliance with a requirement. If I've never flown that type before, I'm certain that I do not have exceptional skill in it. When Flying Cessnas, I have to be more cautious, as I've flown many types before. I try to be a tiny bit careless, and see if the plane bites me. If it's a trainer type, more careless.

During a Transport Canada approved flight test for the purpose of confirming the proper repair of a flying club 172, I purposefully took off with full flaps (only 30 in that model). I did re-land it before I left the runway. The instructor who accompanied me (for insurance reasons) was apparently very surprised this was possible at all. Later in that flight he asked me to demonstrate a roll to him. I would not. I later learned that he was the club safety officer, and second most "experienced" instructor. This was a larger club with more than 25 aircraft. I was reminded that instructors don't know everything.

During a recent flight test in a multi engine aircraft with external modifications, I simply could not make it climb as required (one only one engine) by the prevailing standard. I tried for more than 30 minutes. It did not pass the flight test.

So I return to my previous statement: Up high, in a safe environment, put the plane into slow flight, apply full power, and see if you can make it climb. If you cannot, question the airworthiness of the aircraft. It sounds like Lost Pilot Standing is already questioning the airworthiness of aircraft he flies, with terms such as "condition", "battered" and "abused". I assure you that these terms would not apply at all to the "typical" Canadian Cessna 150 I have seen and flown. Honestly, if the aircraft is not "airworthy" as measured by the standards of maintenance of the airframe, engine, and propeller manufacturer's respective publications, it might not perform as required by the design standards. This is one of the many very good reasons to assure that the aircraft you fly has been correctly maintained.

I would agree that a flying instructor who owns the flying school, and the Cessna 150 they are flying would generally be extended credit as a compotent pilot. As a compotent pilot, I presume that they are flying an aircraft which they have found to be airworthy. That said, with level terrain, I would wonder why that pilot could not accomplish something which the design standard says must be possible (and I have done). I am not in a position to speculate. Aircraft stick flaps, I would hope that intructors are training students what to do when it happens, so as to make the best use of the aircraft capabiltiy demonstrated during certification, which was required for exactly that circumstance.

"Safe", airborne in a battered and abused aircraft? Perhaps not so much...

Pilot DAR

Old Fella

23rd Oct 2008, 05:06

I regularly fly a very well maintained C150 Aerobat and I would not recommend anyone to attempt a go-around with full flap if it can possibly be avoided. With only 100 HP and the drag 40 degree flap generates climb is extremely limited. Wings level and land straight ahead would be my preference in almost every case. I have witnessed an unintentional attempt to go-around with full flap. The aircraft had to be flown level with incremental reduction of flap until sufficient airspeed to climb was attained. That was with about half full fuel tanks and two lightweight POB.

chevvron

23rd Oct 2008, 07:47

I learnt on '150 F models at Marshalls. Full flap go-arounds were part of our training, but you had to re-trim very quickly while slowly retracting the flaps; with your third and fourth hands you flew the aircraft and handled the throttle.
By the way, there is a BIG difference in aerofoil section between these early '150s and later marks/'152s. With these early ones, we were taught the following short takeoff technique: full throttle on the brakes with 10 deg flap; release brakes; rotate at 45 mph and initial climb at 50 mph. You could never do this with the later aerofoil; I know, I tried it when I checked out at Denham a few years later on their '150Gs (frightened the instructor to death too!)

Edited from 20 deg flap to 10 deg flap; haven't flown one in about 17 years!!

dean4689

23rd Oct 2008, 22:12

Full power, retract flaps immediately to 20 degrees. It'll climb away nicely.

Don't mistake the nose down trim change for sink! Flaps up - nose up.

Mark1234

24th Oct 2008, 02:32

So, the target speed for the full flap climb in a 150 would be about 54kts (don't know about the 152)... at which it should climb at least as well as prescribed. How many folks would be willing to pitch for that?

Why would it not climb - see above.. this would be a case where an 'extra 5kts for the wife and kids' would not help. Also note that the prescription is 'at sea level' (presumably standard conditions). High density altitude will really hurt that..

I don't think anyone's suggesting that it's a smart idea to do this, or that you shouldn't retract if in any way possible. Merely that it is possible, contrary to popular belief..

Pilot DAR

24th Oct 2008, 08:19

Yeah, if the wife and kids are so heavy that you need the extra 5 kts, you'd be better off with a more powerful plane. Generally, speed exceeding the manufacturer's recommendations for given a phase of flight is not benificial as expected. Drag increases as a square of the speed, so if you have drag, it is increasing faster than anything else, who wants that?

And, no, the fact that something is possible in an aircraft, and a required design requirement to be shown, does not necessarily make doing it a good idea for casual undertaking by low experience pilots.

Pilot DAR

chevvron

24th Oct 2008, 09:15

Please note 'edit' in my entry of yesterday. STO technique is 10 deg flap not 20!!

cpl4hire

24th Oct 2008, 10:33

Hey SFCC whats with all this venom ?

cpl4hire is talking utter bohoolicks. Just like most other people that have never spent enough time reading their books.

I was only trying to help the guy by suggesting he gets the aircraft cruising in the right attitude (i.e. not slightly tail down) and increasing the power slightly to 2300 RPM.
This was something he could (and did try) on his next outing (with good results).

On the matter of C150 Go Around with 40 degrees of Flap. Yes, it is possible to climb away but the resultant rate of climb is truly pathetic and when I did it as a Rookie one hot summers day I was only able to get away with it by flying between two trees on the extended Runway centreline!
I note Pilot DAR (who also slagged my suggestion for gettiing the most out of the Aircraft in cruise) did at least one of his 40 deg flap go arounds in the winter.

Regards,

CPL4hire

Pilot DAR

24th Oct 2008, 11:28

Winter does create very pleasing performance improvements. Certainly account must be made for the affects of a hot, humid day. The climb performance of a 150 with full flaps out is, as I have previously stated, pathetic. The requirement from the design standard is 1:30. That means that during flight testing in (or corrected for) a standard atmosphere, the 150 demonstrated a change in altitude in a mile of 5280/30=176 feet, or probably 176 feet per minute if you're doing at 60 MPH. If in doubt, go up high and try it. I would have, and reported back by now, but I'm working in Germany this week, and not near my plane.

Pilots of broadening flying skills need to get used to aircraft with non-stellar perfomance. Why? Once you are truly comfortable handling a plane with a best rate of climb of 176 feet per minute, you'll be ready for the single engined performance of some twins when heavy. Recent flight testing I did on a transport category twin, with externally mounted equipment and wheel skis, produced a negative rate of climb on one engine with 110% power on the other The aircraft did not pass. It would have been a bad day if we'd actually lost an engine after takeoff!

Don't knock poor performing aircraft, learn to deal with them the way the manufacturer intended (oh, I've just been told we're going to fly it again - see ya)

Pilot DAR

Lost man standing

24th Oct 2008, 13:23

I should have mentioned that the only time I ever flew a C150 was in Florida, and that the instructor who ended up in the field was flying in the summer. I could not comment on the hours on the engines, but none of the aircraft is new!

Pilot DAR

24th Oct 2008, 14:23

Hours on an O-200 is fairly meaningless, compared to being sure of it's condition. I've flown high time O-200's (3600hrs since overhaul) which were fine, and when disassembled were still fine, and I've flown engines fresh out of overhaul, which were really pretty poor. Sometimes it's the devil you know verses the devil you don't. It's only after the first well done inspection in service you know what you've got.

That said, more than other engine types, O-200's have some tolerance for non-ideal condition, before you really begin to notice a loss of performance in the plane.

In good conditions, you can get a 150 (with 10 flap!) off the ground with 2200 RPM (about 75% power). Yes, it takes a lot more runway, and the climb is poor....

Old Fella

25th Oct 2008, 05:06

Pilot DAR. What purpose did the reduced power take-off serve? Seems like an exercise in futility to me. :(

Pilot DAR

25th Oct 2008, 05:38

For me, a less than full power takeoff, when available space is not a concern, is a zero risk activity (you can always open the throttle to continue if you need to). The benifit for me of doing this in many aircraft types, is be more prepared for a partial power loss during a takeoff, when you are committed to make the best of it. One example of a 25% power loss during takeoff is a stuck exhaust valve on a four cylinder engine, which has happen to me three times. It also provides practice in handling finesse. I remind myself that the somewhat lighter cub I used to fly would get the same load airborne as my 150, and do it on 65 HP - do I need all of that mighty 100 HP? - It seems not! Where this is of the most value to me, is the real finesse required to get a floatplane or flying boat off the water. You can easily cook an engine dragging such an aircraft into the air after an excessive takeoff run. Much better to practice your technique partial power to hone you skills. It makes the availability of full power seem like JATO!

I could be guilty of complacency, if I did not do something to keep my skills up. Whenever I fly with an instructor by circumstance, I ask for a refresher, often I'm told "Oh, you're fine" after a circuit. A complement is nice, but not what I need, it's the challenge to my skills I need. So I gave up on getting it elsewhere, and do it for myself on a regular basis. The people whose aircraft I fly, and the companies who insure those aircraft expect me to keep my skills sharp, so I do.

I think that practice and training are only futile when they are unsafe, wrong, and encouraging poor technique, other than that, if it's safe, and you learn, go for it!

Pilot DAR

chevvron

25th Oct 2008, 07:50

I did a 'reduced power' takeoff once inadvertantly in a Cyclone AX3 microlight. It was a bit gusty 20 - 25 kt at 30 deg to the runway; I began opening the thottle slowly in case a gust lifted the wing, and as I moved forward I thought 'this seems smoother than I expected'.
It was smooth because I was already airborne on just over half throttle after a ground run of less than 50ft! This particular AX3 stalled at 28kt ias two up, so with a headwind of about 20kt, it didn't take much extra speed to get airborne!!

Pilot DAR

25th Oct 2008, 08:22

Yes, I too became airborne at only about 65% power while on the step taking this photo:

http://i381.photobucket.com/albums/oo252/PilotDAR/34onthenicewater.jpg

Pilot DAR

Old Fella

25th Oct 2008, 08:25

pilot DAR, if your explanation of why you conduct reduced power takeoff's in light aircraft was intended to impress I am afraid I find it somewhat confusing. Maybe it is because I am a retired professional flight engineer used to using approved procedures and just a recreational pilot. My understanding is that you conduct take-offs at reduced power regularly so that you will be better prepared to handle a partial power loss during takeoff. I fail to understand why, if you believe that you are honing your skills, you conduct the take-off in a non-standard and non-approved manner. I could better understand what you do if you were to use full power to become airborne and, after airborne, reduce power. I am always willing to learn, however I believe the lesson learned must be based on sound principles. You claim that it is easy to cook an engine after taking off from water after an extended takeoff run. I fail to understand how your reduced power "training" has any benefit in the scenario you mention. I have been involved in numerous "de-rated" thrust takeoffs. These were always an approved operation, within clear limits and properly authorised. I am unaware of any published data which covers reduced power takeoff in light piston engine powered aircraft. You mention getting a refresher if flying with an instructor. I would be interested to know what reaction you got from an instructor if and when you carried out a reduced power takeoff. My own personal pre-takeoff planning includes reinforcing my actions. If I were to suffer a partial power loss before airborne I would close the throttle and bring the aircraft to a stop. In almost all cases this course of action would, to me, be preferable to carrying a 'sick' engine airborne. Old fashioned and unadventurous I may be, but I do not believe intentional non-standard operations are justified.

Pilot DAR

25th Oct 2008, 12:01

Wow, a lot to be responsible for... Fortunatately I have very little need to impress anyone here, because really, what does it matter anyway? I just try to offer a tiny bit of experience, which people may adopt as wisdom if they choose...

"non-standard" and "non-approved" have less meaning in the world of general aviation than they do for large aircraft. Indeed, I'm not sure that "standard" has much regulatory use at all in this realm. As for "approved", the regulatory authorities will generally decline "approving" procedures which differ from those required to show compliance with the requirements applicable to that particular aircraft design. Thus, there are many things which are have no status as "approved", only because nobody sought to approve them, because there was no need at the time. That simple fact does not make them unsafe or prohibited. If, during certification, a certain condition was found to be unsafe, yet did not cause a finding of non compliance with the design requirements, it would be "prohibited", thus obviously "non-approved". Spins being a good example. In some aircraft they are expressed as "Approved", in other aircraft, they are "Not Approved", and yet other aircraft they are "Prohibited". The same aircraft could have two of these conditions, depending upon configuration. So, are you legally permitted to spin an aircraft for which spins are stated as "Not Approved"?

Where the flight manual and placards are silent, air regulations otherwise do not prohibit, and it is not plainly unsafe, it is not forbidden to do it. Pilot's training and judgement must be applied. If training and judgement inadequate, get more!

My choosing to takeoff with less than full power on occasion, when conditions are favourable, is to, in other words, "reinforce my actions" for planning to fly the aircraft in unusual circumstances. It is very certainly my preference, to be safe, to set the power at the time of takeoff rather than as becoming airborne - that is the time a change in power could cause an unexpected loss of power, perhaps more than one sought! By the time I reach the altitude at which I would normally consider it safe to start reducing power, I'm already about the completion altitude for my self appointed excersise.

Reduced power practice on the water is as harmless as step taxiing. If the pilot's technique is such that consistanly good takeoffs are made with less than full power on the water (finding and feeling the step with more awareness) full power takeoffs will be accomplished with greater skill. You can force a waterborne aircraft into the air with power, or you can fly it off with power, and much less strain on the engine. You cannot force it off with reduced power. Therefore, if you got off the water with reduced power, obviously your technique was good, and that was the best way. If I have to check myself out in a floatplane or flying boat I have not flown before, I might do this if I have time.

Yes, if I can detect an engine problem, and abort, I would much rather have the sick engine on the ground. It's not always an option. Several times I have had engines turn sick just as I crossed the trees. If you manage the plane properly, and get it back around safely, the engine will be back on the ground, where it should be, for maintenance. If you forget to fly the sick airplane, you'll be in the trees. There are many reports of crashes after a partial power loss, where it is agreed that plan could have been flown to a safe landing.

I differ, in that I firmly believe that non-standard operations are justified, and indeed, vitally important when conducted safely with preplanning, and not in conflict with flight manual, or other regulatory material. In some cases, formal approval is appropriate. For those pilots who can imagine a non standard operation, which they know they have not training for, they can seek out the training. For operators who can imagine using the aircraft for a task which could require modifications, and might involve degraded performance, formal approval must be sought.

Is towing a glider a standard operation? You're sure flying the aircraft with effectively less than full power! Is flying with a draggy external load, which really affects the performance of the aircraft a standard operation? It can have the effect of reducing performance like having less power. I have approved both such types of operations as only two examples where an aircraft will be flying with less gusto than the "normal" version of that aircraft.

As a personal "check and balance" I like to practice out of the ordinary. It broadens the mind. When I test further out of the ordinary, I apply for a flight permit, that extra check and balance for safety.

Flight permit not required for a partial power takeoff in a 150...

Pilot DAR

Old Fella

25th Oct 2008, 23:43

pilot DAR, I guess you and I have fundamental differences in our approach to how we fly. If you are an approved test pilot with requirement to explore the boundaries I can see why you feel the way you do. Your profile states that you hold a PPL. No doubt, you have vast experience. I cannot fathom how you, as an instance, can say that "you can force a waterborne aircraft into the air with power, or fly it off with power, and much less strain on the engine". If the engine is operating at full power it makes no difference to the "strain" on the engine whether you "force" the aircraft airborne or whether you "fly it off". All the engine knows is that it is operating at full power. We will obviously continue to "do it our own way". As I said, old-fashioned and unadventurous for me. Happy landings. BTW, your photograph is very impressive.

barit1

26th Oct 2008, 00:23

I have a few hours in an old Howard DGA-15P - and I'd expect the Beaver to behave the same - and takeoffs are always most impressive. You must open the throttle slowly, so not to run out of rudder authority (especially in a left crosswind!!!).

On a standard day, with a typical load (4100# TOGW), you will be off the ground within 5 seconds of reaching takeoff power (2300 rpm / 36"Hg). At this point, unless you have an obstacle to clear, you can start backing down to 30" and 2000 rpm to conserve engine life - you'll still climb over 1500 fpm @ 85 kt.

Treat yourself to a video! (http://www.youtube.com/watch?v=nztQ1Ar8JRg)

Pilot DAR

26th Oct 2008, 08:35

Yes.

If the engine is operating at full power it makes no difference to the "strain" on the engine whether you "force" the aircraft airborne or whether you "fly it off". All the engine knows is that it is operating at full power.

All the engine knows is that it is operating at full power, and for how long, with poor cooling due to low airspeed. With unpracticed techinque, you can eventually succeed in draging the aircraft into the air, and keeping there because you kept forcing it up below flying speed, and eventually it stayed. I've done it, I'm not proud. Or, using a practiced technique, you can have the aircraft off the water a mile sooner, and speeding up in the air as intended, with the engine being properly cooled. It might still be operating at the strain of full power, but it is much happier being properly cooled. (and a lot less pounding on the airframe as a bonus)

When I have been asked by Transport Canada to evaluate an unproven float installation, ease of getting off the water (due to "deck angle", or choice of propeller) is one thing I'd be looking for. That goes to how long a pilot is likely to operate the engine at full power and below normal flying speed. From a proper step taxi (which would not be sustained at full power), if I can get airborne, I just did a partial power takeoff. If I did not, no harm done, add a bit more power, and try again.

Old Fella, I do appreciate that we might fly using techniques which occasionally differ, and as long as they are safe in each case, I am very happy to think that you are enjoying safe flying, as we all should. Nothing at all wrong with old fashioned and unadventurous, as long as the underlying skills remain sharp.

A small part of the service I perform relative to aviation, is to evaluate a change to an aircraft within my delegated scope, and recommend it for approval, if I find it meets the design requirement. It's a little adventerous sometimes, though I try to keep the adventure to a safe minimum. It has been the case so far, that all of the "adventure" I have experienced while doing such flying has been a failing of underlying maintenance, not the modification.

I'm pleased that you enjoy the photo. I was practicing glassy water landings to keep my skills sharp. As I step taxiied, I looked out, and thought "I want to remember this in my old age", so I shot a few pics. A moment later, things got very smooth. I was flying! I only had 65% power, and had no intention of leaving the water yet!

I salute your enjoying flying in your later years, after an aviation career, I hope that it continues to reward you for years to come!

Pilot DAR

Mark1234

27th Oct 2008, 00:31

I'm a fairly low hours PPL (and only a recreational pilot.. for now), but have came to powered having flown gliders for a few years, and do aeros in both (i.e. I've spun, many times..). Let me throw in a thought, (maybe two) on a bit of a pet peeve of mine :)

Looking around me at my fellow PPL's (generally around the 100hour mark) they very 'by the numbers'; e.g. 1700rpm, 2 stages of flap on base, etc., etc., Ok, as someone pointed out, the numbers have a habbit of working out.. but they're only 1 solution of many, and a lot seem totally out of their depth with anything non-standard - there's no judgement factor.

That said a significant portion are also terrified of the low speed regime to the point they add 5-10kts to the numbers (speed is safety right?) - we're talking 70-80 knots before getting the nosewheel of a warrior off the ground, and 70+knots over the threshold. Fortunately we're blessed with miles of gorgeous smooth tarmac.

I'm of the opinion that both of the above are a problem - glide approaches, anything other than the 'standard' circuit is 'abnormal', to be feared, passed on the checkride, and forever avoided. We're taught to fear the edges of the envelope, the dreaded stall/spin, but have no idea where those edges really are (it's probably harder to spin than most think.. not that I suggest you go around pushing your luck of course!). I can't help but feel that one day each of us will need that judgement - and judgement is like experience, you get it by doing.

Just as a caveat, I do understand anecdotally, that large 'transport category' aircraft are necessarily by the numbers, not feel aeroplanes. I've only ever sat down the back of those, so I wouldn't know.

Jumbo744

27th Oct 2008, 03:37

SFCC, why? cpl4hire gave a good advice. You need to let the plane accelerate a little after leveling off, and then reduce power to around 2300-2400 rpm.

Finn47

27th Oct 2008, 13:54

I got my initial training on some pre-1965 C150 models. The manual flaps were nice. You could do some instant tricks with manual flaps, once you got the hang of it. Also, the manuals said spins were approved, so up we went and spin we did - and had a good time. So many years ago...

longwings

27th Oct 2008, 19:41

Had to throw away a landing the other week with 30 degrees set in a 152 from about 10 ft agl on a gusty day. Patience & concentration?..yes, everything happens very slowly..drama? No.

Pilot DAR

1st Nov 2008, 22:48

Last week we had a go 'round (pun intended) about Cessna 150 performance with full flaps. I was working overseas, and unable to present evidence to support my claim that a Cessna 150 can safely be flown in a go around with 40 flaps extended the whole time.

I have now returned from overseas, and today flew to aquire the evidence to support what I had stated earlier. Just so you know, I own the plane and the runway, and did not fly the aircraft in a way prohibited by regulation.

THE FACT THAT I HAVE FLOWN THE AIRCRAFT IN A WAY TO CREATE EVIDENCE TO SUPPORT MY CLAIM, DOES NOT MEAN THAT EVERYONE ELSE SHOULD GO AND DO THIS. IT IS NOT A PROCEDURE RECOMMENDED BY CESSNA.

Conditions of flight: 100 pounds under gross, temp 6C, 90 degree crosswind at 5-8 kts. 2000 foot grass runway, no obsticles. Airspeed at liftoff 45 MPH, accelerated to 60 MPH, and climbed out at that speed, never lower. Altitude above ground when crossing the far end of the runway 200+ feet. (and yes, I did use full power). Not quite the usual performance, but surprisingly good, I expected less. I did not retract the flaps at all for the circuit.

Here's the video, should anyone wish to watch:

Video of C150 40 Flap Takeoff - Photobucket - Video and Image Hosting (http://s381.photobucket.com/albums/oo252/PilotDAR/?action=view&current=C15040FlapTakeoff.flv)

So, fly the plane the way your instructor, and the manufacturer say you should, but know that it will do a bit better if you really need it to, and you fly it right....

Pilot DAR

Pilot DAR

3rd Nov 2008, 00:19

Roger,

Appreciate the many merits of the 150! I'd take the 150 over the 152 any day.

The money control is also more or less the time control. Time is money. I would think that generally, people flying Cessna 150's are not doing so to get somewhere quickly! They're flying to build time, so the longer it takes to get where you're going, the better. As for flap use, you may find varying opinions on that. There were a lot of posts on that subject, and my recent reply. Check out the video clip I posted, that was done full flaps in a gentle crosswind, with not problem at all! It was certainly no accident!

Enjoy the 150, and it's wonderful flaps, and have a tiny amount of pity for the pilot who only has a 152 to fly!

Pilot DAR

Thud105

3rd Nov 2008, 14:22

Regarding partial power take-offs, I was taught to never do this, as when at full power another jet in the carb operates -its function being to allow extra fuel to help cool the engine.

Pilot DAR

8th Nov 2008, 15:24

The MA3 and MA4 carburettors which are common to most of these engines, and are installed (MA3) on the O-200 in the 150, contain additional jets for idle and very low power, principally to aid engine acelleration. Once any significant power is selected, the engine is being supplied fuel by the carburettor main jet, whose mixture is also pilot controlled. Presmuming that the pilot has the mixture control full rich (and the carburettor is set up correctly in the first place) the use of partial power cannot cause harm to the engine. If it were to cause harm to the engine fvor takeoff, flying at anything less than full power in cruise flight would also be causing that harm. Operating the engine for a partial power takeoff would be the same as operating the engine for cruise flight, just you began stopped on the ground. (This presupposes that a maximum performance takeoff is not required for safety).

All that being said, I'm not advocating partial power takeoffs for any reason other that pilots practicing technique and becoming more aware of aircraft handling. In certain operations, partial power takeoffs benefit aviation as a whole, in creating good public relations. (noise abatement)Most takeoffs, however, would be presumed to require full power to be conducted safely. Engines benefit from being operated at full power too.

Pilots from time to time experience unusual events. Safely practicing operating an aircraft outside the "norm" though still within it's limitations is an excellent way for pilots to be just a little more ready to handle an unusual event. There certainly cases where an otherwise flyable aircraft, albeit with a defect, has been crashed by a pilot, who perhaps a little more prepared for the unusual event, would have completed a safe flight.

Safe and appropriate practice is always a good idea....

Pilot DAR

Buzzerd

16th Nov 2008, 19:41

I have a question for you 150 pilots out there;
How do you manage your O-200's fuel mixture on cross-countrys?
Do you run it full rich?
Do you lean it till it begins to run rough, then enrichen it slightly?
Do you lean it with the EGT gauge?
Do you run it Rich of Peak?
Do you run it Lean of Peak? (Is that even possible?)
And;
What is the optimum RPM setting, in reference to engine longevity, NOT speed...NOT economy, but to get her to her TBO?
I await your wisdom.

Pilot DAR

16th Nov 2008, 20:36

Buzzerd,

I always lean my Cessna 150, unless staying in the circuit. I lean with reference to the digital EGT. I lean so as to be about 50 rich of peak on the leanest cylinder. You can go more lean, though at higher power settings I'm not so happy with the extreme temperatures to which the entire exhaust system will be subjected. It is possible to damage the muffler with very high EGT's (ask me how I know!). I run at 2500 RPM, as that is the engine speed at which the mixture at each of the cylinders is the closest to ideal. At higher or lower power settings, the mixture distribution is much less even. It is possible to run lean of peak, though I would only do this in situations of dire need to increase endurance. The small increase in endurance could come at quite a cost in exhaust valve/ exhaust damage. As said, I run at 2500RPM unless some circumstance dictates otherwise. You can easily expect 3500 to 4000 hours between overhauls for a well cared for O-200, though expect to have at lease one set of cyilnders replaced during that time. I run Mogas nearly exclusively, and credit the lead free fuel with preventing lead fouling and other unhappy engine events. I have never had a problem which I attributed to the use of Mogas.

I overhauled my engine at 3750 hours since the previous overhaul. I did this only because I found metal in the oil filter. It turned out to be shavings from the crimped on alternator drive coupling (which would only have required removal of the alternator, but I did not know that). The engine was otherwise in excellent condition. The only thing which was non-conforming, was wear on one crankshaft journal which was .0008" undersized in one dimension only. I had the crank ground 10 under, and it will serve me as long as I fly. I have had the 1975 150M for 21 years, during which I have flown it 2660 hours. I could not be happier with it!

I hope this helps.

Pilot DAR

Mikehotel152

16th Nov 2008, 21:21

There are a lot of technical dissections of the C150 as compared with the C152 on this thread and I am certain the authors are very well informed. I can't add to the technical side, but I have flown both aircraft.

In my experience the C150 is lovely to fly but awfully slow. The two particular C150s I have flown managed 90 mph almost flat out with about 2450 RPM. The C152s I have flown many hours on all returned 90 kts from a 2300 RPM cruise. I seem to remember being annoyed at increased fuel consumption despite going slower! Then again, my memory might be a little rusty:}

In summary, quite unsurprisingly the C152 feels like a more powerful evolution of the older C150. I don't recall the handling being much different.

S-Works

17th Nov 2008, 09:36

I had a 152 for years, flew a thousand hours in it all over Europe. Great bit of kit. I fitted K&N Filter, Gap Seals and Sensenich prop when I zero timed the enngine along with a full IFR fit, Garmin, Fuel computer etc. With the mods it would cruise at 100kts at 2300rpm doing 23lph.

Cheap fun flying in anyone's book. I swapped it in for a souped up Hawk XP for private flying. You can't beat a Cessna for performance, value and versatility.

DeeCee

17th Nov 2008, 10:17

Regarding an earlier comment about an Aerobat having 100hp, I thought it had more. Anyone know?

First_Principal

17th Nov 2008, 11:00

DeeCee

FYI we have a standard 100hp C150 Aerobat here, also a re-engined 150hp Aerobat. The former is very underpowered but a tidy machine, the latter is much better power-wise but there's some question over the ability to officially do aero's due to the motor change...

Interestingly my standard (ie. non-Aerobat) 150 is a little better to fly than the 100hp Aerobat - gets to higher places more quickly :)

Pilot DAR

17th Nov 2008, 11:27

American made Aerobats are the same as regular 150's firewall forward (I think the same holds for 152 Aerobats, but I'm not quite as certain). I understand that French made Aerobats may have had different engines, but that is someone else's to answer - we don't get the French built Cessnas in North America very much.

Pilot DAR

DeeCee

17th Nov 2008, 13:58

The one that I flew was the French built version. My recollection is that somebody told me it was 130hp. It certainly went up well!

I find the differences between 150s and 152s quite minor really. Some definately fly a bit faster than others, but unless you are planning a longish trip it won't make much difference in time.

Both are fun and easy to fly.

hatzflyer

17th Nov 2008, 15:11

Just read this thread,I'm supprised no-one has mentioned the fact that the 152 has a more powerfull engine (115/118hp) than the standard (100hp) 150, but the increase in weight is exactly the amount that it takes the extra horses to lug it into the air!
There is no significant differance between a well worn 152 and a good 150 ,in fact a pristine early (read-light) 150 can out perform a slghtly tired 152.Hence it all comes down to the condition of every idividual plane.
The choice of prop is an important factor in cruise performance,most 152's have corse pitch props fitted as standard and don't achieve anything like full power on take off (max power @ 2750rpm). You can get cruise props for a 150 but the climb is degraded.
General rule of thumb is 2 aircraft in good condition,early 150 will come off the deck better,more suited to small strips(250 yards flown light) but a 152 will cruise faster,but not significantly unless you are going over 100miles.
The early 150's fly nicer and lighter controls in my opinion.
I have operated a number of both and ferried many of both!

barit1

17th Nov 2008, 15:31

The early straight-tail 150 has noticeably less friction in the rudder pedals, thus more pleasant turn coordination. If you look at the cable runs and rudder control horns, comparing straight-tail vs swept, you can understand why.

And not to put too fine a point on it - this accident (http://www.ntsb.gov/ntsb/brief.asp?ev_id=20050414X00457&key=1)is related to the above. :uhoh:

dont overfil

17th Nov 2008, 15:55

Our club had several C150 Aerobats. They were FR150L and FR150M models which I believe were fitted with 125hp and 130hp O-240 Rolls Royce Continentals. Being French built they were factory corrosion proofed. They had a shorter TBO than the Lycomings and were more expensive to overhaul but performed very well. 65% cruise was 2400rpm and gave 90kt cruise. 40 degree flap go arounds were not a problem.
DO.

Pilot DAR

18th Nov 2008, 00:45

The several accidents attribuited to the rudder stop, should be attributed to pilots aggressively flying unairworthy aircraft, having failed to observe a very obvious unsafe condition during the preflight inspection. The AD which was written in Canada to address this was particularly silly in it's wording. I used my 150 as the example as to how an airworthy rudder could not possibly jam under such circumstances, and the Transport Canada engineer at the time agreed, after a detailed inspection, but by then the AD was out, and not to be withdrawn. It's hard to argue against making a plane safer, even if it's already plenty safe!

There are certainly cases where a fatal accident is investigated up to the point where a possible cause is found, and then no further. The fact that the possible cause was a poor maintenance/preflight inspection situation, rather than a design shortcoming fails to be mentioned. So to protect against liabilty, Cessna provides service kit with overkill parts in it. Who can blame Cessna?

As applicable to all flying, if you fly an aircraft with a defect, undected or otherwise, you chances of a problem increase. The rudder control horn and stops are very easily inspected during a preflight.

The rudder control runs of both the eariler and later 150's and 152 are effectively identical, other than the use of 3 pulleys instead of 3 fairleads, which should be expected to reduce friction in the system. The rudder itself is quite different, and may require a little more force, but is also somewhat more effective too, and so will not require so much deflection to achieve the same control. There should be no net difference.

A regular 150 does not require a lot of additional rudder during normal flying. However, the addition of a STOL kit has the affect of a slight reduction in dihedral effect, and an improvement in aileron authority, so there is a need for the application of rudder to offset the aileron input, or else the ball will wander all over. I usually lead my turns with a bit of rudder, so the ball stays in the middle from the onset of the turn.

Beginning with the "M" model of the 150, and all 152's, the height of the rudder was increased 6" so as to increase the area of the rudder for improved spin recovery. The "M" is more desireable for airwork and STOL kits for this reason. With the lower touchdown speeds possible with the STOL kit, the better rudder authority is helpful in crosswinds.

Agreed, full flap go-arounds are no problem in a 150, as I presented with a video earlier in this thread. I am pleased that some pilots will give the credit due to such a good and economical aircraft design. I think that the Skycatcher will have some stiff competition in it's predecessor!

Pilot DAR

LowNSlow

18th Nov 2008, 13:02

I managed a 40 deg flap takoff as an inexperienced PPL with the yolk still wet behind my ears. I'd forgotten to retract the flaps after checking their travel. The 150 was a good one and levitated into the air as I was heading straight into a 10 knot wind. It didn't want to go forward very quickly and I soon realised what I had done. I just eased the flaps up gently and she accelerated away with no hight loss.

I had an A150L which was an imported Aerobat with the Continental O-200. Lovely little thing. Shame that she was wrecked in a gale. The FRA 150 had the R-R Continental O-240 which is basically an O-200 with O-360 cylinders to take the capacity out to 240 cu ins. Huge improvement on the climb and makes it a more usable aerobatic machine. Rumour has it that the R-R built O-200s put out 105hp compared to the 100hp (on a good day) that was expected from Continental's offering.

bilhar

18th Nov 2008, 14:44

pilot dar

did you have to do any adjustments to engine settings to use Mogas or are avagas and mogas interchangeable without adjustment

I assume we are not allowed to mogas use it C150 in uk

BEXIL160

18th Nov 2008, 18:01

The UK CAA stance on MoGAS in Cessna 150s and many other types is here

http://www.caa.co.uk/docs/33/AN98.pdf

and here

http://www.caa.co.uk/docs/33/AN98A.pdf

from which, under certain conditions you CAN use MOGAS in a Cessna 150 in the UK

BEX

Pilot DAR

18th Nov 2008, 20:25

Bilhar,

There are no adjustments to the O-200 to operate on Mogas, though be cautioned that the configuration of the engine and fuel system can affect the interchangeability of Mogas and Avags use. In particular, "O" rings and other seals, including in particular, the plunger of the fuel strainer, may be affected by the Mogas (they could swell up). Also, some carburettors have a foam float, others a metel float. You'd rather have the metal, as the Mogas will not attack the metal, and it may the foam.

There are other considerations with Mogas use. Read and understand them. Transport Canada has an excellent document #TP10737 on the subject (I contributed to it). Once you have a good understanding, it is an excellent fuel for 150's. And the icing on the cake is that in Ontario, Canada, I get the road tax imposed upon the Mogas refunded to me, as I did not use the gas on the road!

Pilot DAR

bilhar

19th Nov 2008, 10:30

I knew it to good to be true we allowed to use mogas conforming to bs4040 in uk
ie 4 star leaded petrol but its sold in very few outlet at price same as avagas 1.59per litre in herts

LowNSlow

19th Nov 2008, 12:58

bilhar, it will have 4 times LESS lead than 100 LL so will reduce any plug fouling problems you may encounter when using 100LL in a Continental A-65 or it's siblings. Bit of a problem carting it around in 5l containers though......

Pilot DAR

19th Nov 2008, 12:59

I have no knowledge of the UK requirements for operation of an aircraft on Mogas. I can say that technically, leaded or high "octane" gasoline is not requirement for the O-200, and many other low (7:1) compression engines. The absence of alcohol is important though. The O-200 will happily run on automotive gasoline (free of alcohol) of the lowest "octane" rating available. The test methods for octane in Avgas, and "octane" in Mogas vary slightly, but are close, particularly for normally aspirated engines. Thus the fact that the O-200 was born to run 80/87 (note 80) means it does not require the "octane" rating of even the lowest automotive gasoline, which is generally around 87. The purests here will be able to offer more detailed comments, but that's the general idea.

If regular automotive gasoline (free of alcohol) is not approved for use in appropriate aircraft in the UK, someone should be considering that. The downside however, may be that regular automotive gasolines contain alcohol in the UK (I don't know). These gasolines would work (we flew a 150 with a slightly modified O-200 on pure ethanol for two years) but there are changes to be made. Still a good idea though...

Pilot DAR

Mickey Kaye

19th Nov 2008, 15:11

I bet the "engine" itself would run fine on it.

BEXIL160

19th Nov 2008, 15:46

Ahem, there's more form the CAA about the use of unleaded MogAS here

http://www.caa.co.uk/docs/33/AN98C.pdf

and a very good saftey sense leaflet here

http://www.caa.co.uk/docs/33/ga_srg_07webSSL04.pdf

BEX

Big Pistons Forever

19th Nov 2008, 15:58

Re reduced power takeoff.

When teaching for the Cpl I always did a reduced power takeoff as a dual exercise. The purpose was to expose the student to how the airplane would feel and what the performance would look like when attempting a high density altitude takeoff. It was also valuable for reinforcing the importance to fly the airplane on speed and perfectly coordinated. The difference between a few knots too fast and the ball 3/4 out of the cage can be as much as a 50 % reduction in climb rate for a low powered airplane and high DA.

I also used the "make the airspeed indicator go to zero" exercise (in the C150/C172) part of my slow flight training. I was amazed at how many students had never been slower than 55 kts and how they thought they were going to die if the stall warning horn came on on flight. Concentrating on what the aircraft felt like at low speeds was a good confidence builder and emphasized the point the airpalne should always be doing what you want it to be doing at any given part of the flight.

barit1

19th Nov 2008, 16:14

Concentrating on what the aircraft felt like at low speeds was a good confidence builder and emphasized the point the airpalne should always be doing what you want it to be doing at any given part of the flight.

Absolutely, and there is nothing new here. That was part of the USAAF WWII pilot training syllabus, and my father employed it there and for the next 50 years in civil instruction. :)

Pilot DAR

19th Nov 2008, 18:25

Yes, the airspeed indicating zero in an airborne C150 was I problem I encountered during the initial flying in my recently purchased STOL C150 21 years ago. Whenever I flew in the STOL speed range, the airspeed information was not useful. Shortly thereafter, I purchased a Bell 206 helicopter airspeed indicator, and marked it appropriately for Cessna 150 speeds. As that airspeed indicator will indicate reasonably down to 10 MPH, it does the job. There is a little position error at the high angles of attack, but by flying in dead still air, and comparing the GPS, it's only 1MPH or so. My lowest indicated airspeed during level flight was 21 MPH, with 25 MPH being easily attainable. You don't want to spend too long there though, as the engine gets warm! Bear in mind though, takeoff, approach and landing are not possible at such speeds though, becasue the angle of attack is such that you strike the tail before the mainwheels touch or leave the runway as the case may be (ask me how I know).

As an aside, I used to fly a late model Robertson STOL Cessna 185 on Wipline ampibious floats. The Robertson Flight Manual Supplement for that aircraft instructed that a runway takeoff be rotated at 32kts IAS. the factory airspeed indicator is just quivering at that speed, but the plane would fly. This was possible because the angle formed between the main wheels and the transomes of the floats was large enough to permit the high angles of attack on the ground to really get the STOL kit doing what it should be.

The use of alcohol in aircraft has considerations in addition to operating compatability, those are fuel flow and flight manual information. The lower energy density of the alcohol results in the possible need for changing the jet size in the carb to permit increased fuel flow. If there is a greater fuel flow, the preformance information (range) in the flight manual is no longer valid. The problem is that depending upon the mixture of gasoline and alcohol in the system the fuel flow varies considerably. The Pure enthanol C150 I used to fly had a fuel flow at takeoff of 11 to 13 GPH, at takeoff, and 9 or so in cruise. When run on pure gas, it was more like 7 to 9 on takeoff, and 5 GPH in cruise. When taking off on pure gasoline, you'd have to have the mixture about half way out, or the engine would flood, and quit. These variabilities made the aircraft very operator technique sensative, and thus not eligible for STC approval.

Enthanol works, but there's more to it than meets the eye.

Pilot DAR