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I'm reading a flight manual where they are talking about the tendency of the airplane to Mush at high altitudes. I think I know what that means, but I just want to be sure.

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I would define it as loss of positive control response in a "normal" timeframe or a lack of "normal" response to inputs. This may or may not be accompanied by uncommanded changes in any axis.

Typically it implies slow speed / edge of performance behaviours..eg, at or near maximum ceiling, maximum angle of attack, stall speed, rather than loss of control due to excessive speed. Some aircraft (eg Extra, Spitfire, C152) maintain positive feel right down to stall, others (modern C172) get decidedly sluggish.


Anyone else??


Darryl

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The best way to explain "Mushy" controls to a non-pilot or someone who hasn't experienced them yet is to compare it to driving your car in mud. Notice how you make large control changes and nothing really happens initially. That is "mushy control". Same thing in the airplane. When the airplane starts to "mush" (I like the word "wallow" more as more people know what that is) it starts to respond very slowly to control inputs, even when you're perfectly within the normal operating range of the airplane (i.e. safely above stall).

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I was always of the understanding that a "mush" was when the airplane falls out of a climb without a stall. There is at least one older model Ultralight that the pilot who wrote about it could not get the plane to stall and he said that the best that he could achieve was a mush, which is easily recoverable, and never a full stall, which is not always so easy to recover from.

I cold be wrong, but that is what the evaluating pilot wrote about the aircraft in one book, published in the mid 80's, as a guide to the different U/L aircraft available at the time.

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You're going to notice "mushiness" at low airspeeds. When you are flying a plane in slow-flight, you will understand this. To emulate; pick an altitude and hold it while bringing the power back. As you slow down you will have to add back-pressure to maintain altitude. When you start to near your stall speed, start bringing the throttle back in and stabilize your airspeed just above stall speed. You should now have a nose-high pitch attitude and the stall horn/indicator going off with the airplane in level flight (if you are doing it right.) Now make a 30° banked turn 90° to the left/right (your choice) and notice that the airplane is slow to respond to your control inputs. The reason is because instead of smooth air travelling over your control surfaces, you now have turbulent air flowing over the surfaces which effectively reduces their aerodynamic effectiveness. You have to make larger control inputs to do the same as smaller inputs do in normal (faster) flight.

While this test is nice, please limit your bank to 15 degrees. 30 degrees is asking for a stall/spin.

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I guess...I was asked to demonstrate it at 30° on both the single and multi commercial checkrides. As long as you are staying coordinated and not stalling the airplane, you aren't going to spin; that's the point of the maneuver after all. I suppose that you don't even need to go to 30° to feel what we are trying to describe; you still feel it at 15°. I've just been hammering out lesson plans lately and happened to have done slow flight a couple days ago.

*Disclaimer: Unless you are a licensed private pilot seeking a commercial rating, do not attempt to perform this maneuver using more than 15° bank; in real life, in a real plane. If you do, you do so at your own risk.

**If you just want to try it in Flight Simulator; go nuts!

I don't know where you're flying at so I can't make an educated response on your personal training, but all of the instructors I've ever flown with have cautioned me to not exceed 15 degrees of bank during slow flight, coordinated or not. If a gust hits you wrong while you're in true slow flight and you're in a 30 degree bank, it doesn't matter how coordinated you are, you're in a stall. A good pilot doesn't put himself in that position.

Additionally, both the Jeppessen and Cessna Private Pilot books and the FAA's Private Pilot PTS only speak of a "medium-banked turn", which is generally considered to be less than 20 degrees. If you're doing 30, great on you, but I don't think it's a safe thing to be doing.

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if your at 20 30 degree in a slow flight and you hit a gust that stalls you its not a big deal as long as you have ALTITUDE and or you don't place yourself in a deep stall or if you're not in a FULL stall but you're in a buffet, also it depends what you are flying. there are SOME aircraft that will NEVER stall straight they always drop a wing first, My 182 even with vgs stol kit and wing extensions will stall flat ahead, I have stalled my 1959 182 through about 6 thousand feet of air just yoke in my lap and experimenting with my ailerons at a full stall. Ive done High speed stalls in steep turns and it still stalls straight ahead or should I say in the attitude of the bank, as long as im coordinated havent tried a high speed stall uncoordinated not that I would try might snap me into a snap roll. It really depends how you are placing yourself in the situation. say LOW to the ground HIGH density altitude LOW power output HOT day and Terrain around then YES your gonna get killed if you dont know what youre doing but today in age most pilots I know are wussies, they are not stick and rudder pilots they are auto pilot pilots, and these pilots usually SUCK at flying. I cant even STALL my 182 at 3000 ft at full flaps and full power without exceeding 30 degrees it just climbs and climbs. I DO NOT ADVISE newbies do this. If your comfortable with your plane then do it but if not, DONT and spare your life

I will say something, a GOOD pilot will get to KNOW his aircraft and that means putting himself in situations he wouldnt normally be in, Now some are good enough to do it by themselves some need instructors with them. I have never spinned my 182 because of my training, I have saved my 182 from entering spins MANY MANY TIMES as I pushed my envelope on high speed stalls, slow flight etc, I believe its the duty of a pilot to train as much as possible in abnormal attitudes. The pilot that didn't do spin training For example is usually the dimwit who spun on approach killing all his passengers with him.

as for the MUSHING I would say its just that the control input response is not brisk. the description for driving in mud would be the closest comparison I could make.

Really? huh... 15-30º here in Canada, and over 30º is steep. You know also when I got my gliders license we did spin training from a medium banked turn, with the controls crossed. It was very effective because this is how your most likely to spin a glider on the turn into final. Making a turn being high and adding a bit of a slip, bang stall spin crash... you know the rest. Also effective for getting out of the flight levels in a glider... oops.

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I did a lot of my commercial slow flight exercises up to 30 degrees as well. In fact, it was a performance criteria on the flight test. And as seaniam81 said, medium-banked turn is between the ranges of 15 and 30 degrees (here in Canada anyways!).

man I dont remember very well but I think in my training we went all the way to 45 degrees, Im pretty sure FAA asks for 45 degrees as long as its within aircraft limits

http://www.avweb.com/news/leadingedge/l ... 220-1.html this is all I cared to find lol.

The terms I've always heard were "shallow" being 10* and under, "medium" being 11*-20*, "standard" being 20*-30*, and "steep" being anything over 30*.



Steep Turns and Slow Flight are two different things. We are talking about banking while in slow flight and what is the safe "maximum" bank for the maneuvers.

BTW, what I was talking about with stalling while in slow flight, specifically in the Cessna 172R for this example.

Typically "slow flight" is approx. 50-55 KIAS for a 172R after a max gross weight takeoff (2450 lbs). Flaps Up stall speed is 44 knots. At 30* bank, stall speed is 48 knots. That's cutting it really close to stalling if you're doing 50 knots. Having done slow flight in even light chop, 5 knot excursions aren't unusual. That means that you can easily stall the aircraft. The point of slow flight is to learn how to fly slow, near stall, without actually stalling. If you stall, you've failed the task. So, putting the airplane in a condition where you're within 5 knots of the stall speed for the given bank angle is setting yourself up for failure and thus is not a safe practice. That's where my issue with using 30* of bank is. You're not learning anything by stalling and potentially spinning the plane, no matter what the altitude, especially when the aircraft is explicitly not spin approved. For a glider or spin-approved aircraft, there is some merit to "cutting it close" while under the watchful eye of an instructor or safety pilot because the risk of bending or breaking the aircraft is very low, but for most training aircraft, you're putting yourself in a dangerous position. To assume that an aircraft can safely survive an accidental spin ignores the accidents that prove otherwise and the reason for the regulations that require aircraft to be approved for spinning.

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I can kind of agree to the point that you really are not learning that much at 30 degrees of bank if we look at slow flight in by itself. However, in terms of considering what is the safe maximum bank, I tend to disagree that 30 is necessarily that far out unsafe (or asking for a spin and such). After all, every commercial pilot in Canada who does their training here are expected to, by standards, be able to demonstrate control of their aircraft in slow flight at 30 degrees of bank. For private pilots, it's a little bit more lenient, and while I don't necessarily feel that 30 degrees really adds much to say the 15 degree standards that some of our private pilots are required to perform, the performance involved does constitute a fine-tuning of skill that is expected from some of the pilots here. To be fair, after being required to do this through some of my training, it's not really that much more dangerous than performing a power-on stall, or simulating an engine failure in a twin (heck, you can spin or flip the airplane over in those exercises too if you screw up royally, and boy can they happen quick). I mean, sure, the stall speed increases the further you bank, but one isn't necessarily chasing the airspeed indication either (slow flight isn't so much a set airspeed as it is a condition). The point is to keep the airplane between stall and endurance and maintaining control in the worst case scenario; with worst case scenario being the focus of most training exercises done in an airplane. If you are a private pilot, or training for the ticket, I can kind of understand instructors telling you not to go too far in terms of bank. But it really isn't as dangerous as it seems in terms of practicing such maneuvers for training purposes with a little bit of experience and giving yourself a safety buffer in terms of altitude and space. It's not like one normally does this intentionally during a normal course of flight with passengers on board (even if we do experience slow flight during every landing ). Even then, a stall in a bank doesn't necessarily equal a spin either.