Pitch is everything

[Sans Anoraque]

When I was doing my PPL, my instructor mentioned that when he was first learning to fly his first instructor had said 'Whatever plane you fly - pitch is everything', He (my instructor) then said that it was only when he had around 800 hours under his belt that he truely understood what his instructor had meant.

As a lowly 100 hour PPL, I think I know what he meant (I'm assuming it was that nothing is more important than AoA) but that's not exactly what he said, so perhaps I'm still in the dark.

Discuss.

[Hour Builder]

I am even less experienced than you, but to me I can see what your instructor meant. As long as you are always aware of what is going on around you, and fully understand how and when to adapt your pitch accordingly, you should never get into too much trouble. (ie with or without power etc). Am I wrong?

HB

[High Wing Drifter]

I think he is refering to the three Ps:

Pitch + Power = Performance.

[Hour Builder]

High Wing Drifter I have never heard that term before, learn something knew everyday.

Did you think I was referring to the 3 P's? If not and you were infact talking about Sans Anoraque's instructor, correct me if I'm wrong, but would he not have said "3 P's if referring to it?"

ahaha

HB

[mad_jock]

Hour Builder this isn't a trick question or meant to be cheeky.

What do you understand you are doing by triming a pitch?

MJ

[Fournicator]

Fly Visual Attitudes! Don't chase needles, like many PPLs seem very prone to!

[slim_slag]

Sans Anoraque,

Being a bit pedantic here, but you are more correct than your instructor when you say "Nothing is more important than angle of attack". If you get to depart successfully from a high density altitude airports you will notice you climb out at a more shallow angle. The angle of attack is the same, but the pitch attitude is less because the relative wind is coming from a different direction when at high DA. So pitch isn't everything, and thinking that way can be dangerous if in the mountains

[IO540]

Pitch trim is everything!

Makes a vast difference to the workload of flying.

[Shaggy Sheep Driver]

When we learn to fly we do it by numbers. Climb-out speed, cruise speed, approach speed etc. We even use that dreaded term 'stalling speed'.

But what we are really doing is setting an Angle of Attack for the wing. And while under certain steady-state conditions A of A can often be related directly to a speed, it is far from always so, and a pilot should always think A of A rather than speed.

A of A is the only thing the wing ever thinks about.

The best way to gain an appreciation of A of A is to do an aerobatics course. You will soon experience zero airspeed with no stall, and stalls occuring at very high indicated airspeeds. But the stall will always take place at a particular A of A for any given wing - it never varies (unless the wing varies - like extending the flaps).

That's what he meant, and he was dead right.

SSD

[mad_jock]

ya buggers I was going to try and lead him/her through so they could work it out for himself/herself :D

[slim_slag]

I think sans anoraque had already worked it out, he was confused by the instructor, which is why he asked the question :)

[Hour Builder]

Mad Jock, sorry I've only jsut read that thread, but although your question to me has been answered by others, I would have said the same thing IO540 said, "Makes a vast difference to the workload of flying." By trimming the aircarft, you calibrate the aircraft control column to a new neutral position do you not?

HB

[Shaggy Sheep Driver]

SA's instructor said 'whatever plane you fly, pitch is everything'. Not pitch trim - which varies in importance from aeroplane to aeroplane depending on how heavy the out-of-trim forces are. But coud never be described as 'everything'. Some simple aeroplanes don't even have it, and in many others it can be ignored.

A of A is absolutely everything in flying. It's the wing that flies, and A of A is the only thing the wing cares about. Not speed (at least not until mach effects become noticable), not how overloaded the cabin is, not how hot it is, not how much 'G' you are pulling - nothing except A of A. Of course, many of these things change the A of A, but the wing knows nothing of that. All it knows is A of A.

That's why that instructor (nearly) said: "whatever aeroplane you fly, A of A is everything".

Have a read of that superb book that every pilot should read - Stick & Rudder. That explains it all, in a most understandable way.

SSD

[Sans Anoraque]

To be fair SSD, it was 'Stick & Rudder' that lead me to that conclusion anyway.

I don't remember AoA being stressed all that much in my initial training. Perhaps it's easier for newbies to initially think in terms of airspeed?

Anyway, thanks for the interesting replies from the more experienced. Keep 'em coming.

[Shaggy Sheep Driver]

As I said in an earlier post, we are taught to fly 'by numbers'. That's because the concept of A of A is not easy to grasp until you've been flying for a while, so to teach A of A from day one would be very difficult, since the student would have no 'background' to apply it to. So by the numbers it is.

However, afer we've been flying a while we should have begun to realise that 'by numbers' isn't the whole, or even the correct, story. That's when we can start to think 'A of A' and fly 'A of A'.

When we are students, it seem counter-intuitive at the stall to have to pitch the aeroplane nose-down to recover from a condition where the aeroplane is already descending. If you're thinking 'A of A', it's the most natural thing in the world to do and is instinctive.

Edited to add that the one instrument I'd really like in the Chippy is an A of A indicator. But they seem to be the presrve of fast jets and Concorde.

SSD

[IO540]

One could argue for ever which one thing is "most important" in flying. Based on actual accidents one could say that checking there is juice in the tank might be important :O

However, I would argue, for general GA flight (not aerobatics) and in the context of a 45hr PPL and typical PPL pilot currency:

If AOA becomes actually critical to flight, and if this happens frequently, then the pilot will end up dead pretty soon.

One just doesn't operate an aircraft that close to the line.

[Sans Anoraque]

Edited to add that the one instrument I'd really like in the Chippy is an A of A indicator. But they seem to be the presrve of fast jets and Concorde And the Wright Flyer. A piece of ribbon tied to a strut if I recall.

[Shaggy Sheep Driver]

If AOA becomes actually critical to flight, and if this happens frequently, then the pilot will end up dead pretty soon
One just doesn't operate an aircraft that close to the line.
.

10540 - I think you've missed the point. It's nothing to do with 'being close to any line'. A of A isn't something that 'might become critical to flight', as if it's only important if you exceed the max A of A the wing can handle without stalling.

A of A is flight. It's all the wing knows about, the whole time it's flying. And if you're flying an aeroplane, what you are really flying is a wing. The rest of it is just there to enable the wing to do its job (tailplane etc), to give the crew somewhere to sit (fuselage), and to add energy to the equation (engine and fuel system - these latter are optional in that gliders dont have them).

That's why SA's instructor said what he did.

SSD

[stiknruda]

IO540 - you are obviously no big fan of aerobatics:(

Stik

[FlyingForFun]

Agree that AoA is everything.

However, as has already been pointed out, most of us don't have an AoA dial. Therefore, for non-aerobatic flight, we use a combination of pitch and power to produce the required AoA.

Most people have no problem setting the required power. But it takes a bit more experience to be able to set an attitude automatically, without having to think about it. And if you can do that accurately, then your AoA will be correct, and the aircraft will perform correctly.

(Stik - can't speak for IO540, but I love aeros. However, I'm not suitably qualified to talk about how to judge AoA when doing aeros, although from my limited experience I'd say that the flightpath can vary sufficiently that the attitude is no longer a suitable indicaiton of AoA, which is why I've excluded it from my general statement above. :ok: )

FFF
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[Andy_R]

OK, stupid question time, but would love to know the answer...........

Do different wings have different A of A's?

Or is it a constant regardless of wing shape/chord/ span etc.?

[High Wing Drifter]

Do different wings have different A of A's?
Yes, most certainly. Low drag swept wing designs can tolerate incredibly high AoA as can delta wings, just look at past footage (sadly) of Concorde on Final approach. They are generally low lift wings with about +3deg positive pitch in the cruise at umpteen-loads knots, as the speed decays they rely on high AoA (as well as high lift stuff like slats'n'flaps) to stay in the air.

As for chord/span. Flaps increase the AoA of the wing, creating more lift, hence the reason why you can pitch at cruise attitudes when well below cruise speed.

[18greens]

Theres a lot of discussion here about pitch and AOA which are undoubtedly important. In fact AOA is very important but...

Was the original question not about flying the picture or flying the attitude when he referred to pitch being very important.

If you lost all of the instruments in a light aircraft you could still fly and land it in VMC without difficulty if you had a grasp of attitude rather than flying the numbers.

In any light ac if you covered up all of the insts I bet you could make a decent fist of a landing based on the noise the engine is making and the attitude of the ac outside the window.

Attitude adjustments are far easier to do by looking out the window rather than chasing the ASI. (Ask any IMC student, a peek is worth a thousand scans)

[Shaggy Sheep Driver]

Do different wings have different A of A's?

Or is it a constant regardless of wing shape/chord/ span etc.?

Cloud69 - not a stupid question at all. I'll try not to give a stupid answer. ;)

To add to HWD's answer, the A of A is actually the angle between the mean wing chord and the airflow - that is, the angle at which the wing is presented to the airflow. So a wing doesnt 'have' an A of A, but 'experiences' whatever A of A it is presented with.

The problem comes when the A of A reaches the angle at which the airflow can no longer follow the top surface of the wing, and breaks away. This is the stall. That angle depends on the design of the wing - including aspect ratio (chord to span ratio), and cross-sectional profile. These factors also affect how the wing behaves at high A of A - for instance, whether the airflow suddenly detaches, or does so more progessivly - or not at all.

The example of Concorde HWD gives is interesting - narrow delta wings like that will work at extremely high A of As without stalling - but the drag goes up at a phenominal rate, so as a delta is pitched up it genertaes more lift and more drag (as do all wings). But whereas a conventional wing will reach a stallling angle (around 15 degrees on most light aircraft) the delta just goes generating more lift and more drag - much more drag. Soon it reaches a point where, despite full engine power, the only way is down, and the aeroplanes sinks earthwards.

SSD

[High Wing Drifter]

In any light ac if you covered up all of the insts I bet you could make a decent fist of a landing based on the noise the engine is making and the attitude of the ac outside the window.
I doubt you could sense the wind noise different of say 10kts and on approach you may well have the engine on idle or low power so I doubt those cues will work well. However, the level of mushyness in the handling should be an excellent indicator. You know how utterly unresponsive the a/c just prior to the stall and how realtively unresponsive it is on approach. The difference in 15kts is quite marked (on the little un's I've flown anyway).

[Andy_R]

Thanks for that guys!!!

[stiknruda]

FFF

In short, generaly civvy aerobatic capable machines don't have an AoA indicator.

So how does the aerobatic pilot assess AoA? Quite simply through practice, initially one stalls or departs from the attitude being flown, then one begins to register the buffet, then one learns to ease off and only mildly "nibble the buffet", for greatest effect.

Then an amazing thing happens - you suddenly realise that the buffet and ensuing stall happen at a certain stick position, regardless of speed, bank, etc! That it works just the same for negative as for positive G makes flying even more magic, ie whilst inverted, the same stick position will cause the aircraft to stall regardless of configuration.

The military have AoA indicators primarily to assist the operator turning the flying machine into a weapons platform and doing so in as simple a manner as possible.

So very simplistically, even those unfortunates who have to to fly William T's aeroplane's have an accurately calibrated AoA indicator - it's called the column/yoke or stick!

Stik

[englishal]

However, the level of mushyness in the handling should be an excellent indicator.
I did this exercise once, covering up all instruments except for oil temp, and oil pressure and flew back in, joined and landed.

Very interesting it was too, combining the visual attitude with the "feel" of the aircraft and I made a perfect landing. I often wonder why people spiral to their death when an ASI fails or they take off with the pitot cover still on.....?

[FlyingForFun]

Stik - thanks for that, very interesting. The only time I've inadvertantly stalled an aircraft was at the top of a loop, and I knew I'd stalled because I registered the buffet.....

But I think your reply has confirmed my earlier reply, and that of others: during non-aerobatic flight, the principal way of telling the AoA is by a combination of power and, more importantly, attitude - but that's not true for aerobatic flight.

FFF
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[slim_slag]

Hmm, I think the discussion of aerobatic flight came from an earlier significant misunderstanding of what the thread is about (which probably comes from a misunderstanding of aerodynamics). Then it got onto how you can detect the stall without using an AoA indicator. None of this from you FFF, but surely it's the same wing on the way to the aerobatic box as it is in the aerobatic box :)

[Sans Anoraque]

Englishal - I suspect that kind of excercise would be more than interesting for someone with my level of experience!

After all, some pilots still manage to stall on final turn, even with fully working ASIs.

[slim_slag]

I think you would do just fine Anoraque, you should try it. People stall-spin-die on the base-final turn because they use rudder in an attempt to tighten the turn, not because they have poor airspeed/pitch control.

[englishal]

You should do it with an instructor then;)

Another interesting exercise is to fly to the local area, then fly back in, join and land using nothing but the rudder, trim and power......ok, not land, but take it to the runway using trim only, you can use the stick / yoke to flare if you like:D