CFI myths..Special VFR day/night et al

[Timebuilder]

There's only one small problem - no physicist in the world agrees with what you just wrote.

There may be several reasons that no one agrees, but they don't worry me. In order for a calculation to be relevant, you have to have an equation that models the relationship that is the basis of the hypothesis. I suspect that this is the reason for disagreement.

All we are talking about is taking a pilot tube that is pointing in one direction where the forces are additive and turning it to a direction where the forces are subtractive. It's that simple. What makes it interesting is the fact that the pitot tube gives us a representation of the flow of relative wind over the wing. The question for the model is this: how quickly is the orientation being changed? Under normal conditions, the change is so painfully slow that the forces involved have plenty of time to "keep up" with the evolving situation, as the airplane is affected over time by the fact that its relationship to the wind is changing. The key is that at a point found by the extreme maneuvering of ag planes on a windy day, these changes happen much more quickly than than any "timed turn" experiment would reveal.

Perhaps additional variables are coordination and pitch attitude, since we are apparently not discussing an effect in a "normal" turn. In this case, we have to ask "how abnormal" a turn do we have to look at?

It's an interesting question. This would certainly explain problems that might arise during the modelling process. Does the turn have to happen so fast that it is a skidding turn?

 

[VNugget]

Why would a continuous steep turn not demonstrate the desired effect, if the airspeed is low enough and the load factor is high enough to reach come close to a stall? Why would a 90 degree show the effect but not a 360, or a 720, or a 1080, ad infinitum? My guess is because it is a less controlled experiment, and more likely to introduce factors such as trying to make the upwind and downwind turns with the same-shaped ground track, or in the same amount of time after a crabbed crosswind leg, etc., but then again, who am I to pass judgement?

 

[Checks]

Fact: For a given pitch and powersetting the airplane will maintain the same airspeed and rate of climb regardless of turning upwind or downwind.
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I agree but it takes time for the aircraft to achieve steady state conditions.

Ask any pilot who flies slow aircraft, close to the ground, whether the downwind turn is an illusion they will agree that is isnt.

 

[Sctt@NJA]

Ask any pilot who flies slow aircraft, close to the ground, whether the downwind turn is an illusion they will agree that is isnt. [/B][/QUOTE]


I don't have to ask one, I AM one. I have several hundered hours of 7ac aeronca champ time. Low, slow and way underpowered with 65 horse power. Much of that flying time is under conditions where I was flying lower than nearby terrain or obstacles. With this airplane you tend to fly between hills rather than over them.

And you don't have the power to get yourself out of trouble either. Its very possible to find yourself in a position where you are in a "bowl" with rising terrain on all sides and very limited climb performance to help you cope. Very important to use all advantages of terrain and wind to your advantage. Flying into the wind for better climb angle is critical. Locating a thermal helps too.

I have tested the downwind turn (with a bit of altitude) for loss of airspeed, and there was no loss. No gain turning into the wind either. These are my observations, so for folks who have seen otherwise I can't explain.

The science (which says you wont lose airspeed in a downwind turn- i mean other than induced drag) meshes with my personal experience in airplanes.

I just wanted to point out that I am not just speaking from a text book. And also, I wouldn't have tested it myself if I never had doubts!

 

[Checks]

I went out and did 20 degree bank turns with the AutoPilot on and power set yesterday.

I used 90kts and the airspeed would rise to 93kts as I went into the wind and then would decrease as I was turning downwind.

Maybe I did something wrong but I saw the airspeed change Yesterday.


I will say that all you naysayers have me wondering if I am missing something. The next day the wind is really howling I will do it again.

 

[100LL... Again!]

The real issue -

An airplane is not a laboratory, and it is not possible to isolate single factors. This is why flight test aircraft are often fitted with enough computers to run the space shuttle.

The physics say no. Some of the pilots say yes.

If the effect is there, it is for some other reason.