Graveyard Spiral

sdfcvoh said:
I would pull power and trim nose up full then pull out two twists (usually gets glide speed).
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The configuration you describe is usually recommended for a letdown out of the clouds with a working panel by someone who perhaps isn't instrument-rated. Personally, I would be very leery about making any control movements that would induce a yaw or roll in the airplane because I could not detect it. I'd make a small power reduction and leave it at that.
 
sdfcvoh said:
2nd question then: Even in a spiral, wouldn't the airplane maintain it's trimmed speed?
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No, it maintains its trimmed AoA. (See pitch thread. ;)) That AoA corresponds to different airspeeds as the bank increases. In a 60 degree bank, the airspeed should increase about 40%.
 
tgrayson said:
No, it maintains its trimmed AoA. (See pitch thread. ;)) That AoA corresponds to different airspeeds as the bank increases. In a 60 degree bank, the airspeed should increase about 40%.
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Okay - that does make sense! I'll check out the thread too - but I can picture why now that you point it out. thx!
 
sdfcvoh said:
Okay - that does make sense! I'll check out the thread too - but I can picture why now that you point it out. thx!
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Yes, you've experienced it while doing steep spirals for Commercial/CFI students. As the bank increases, it takes powerful back pressure to keep the airspeed from increasing.

On the last page of the pitch thread, I posted a diagram showing the direct relationship between elevator position and lift coefficient. The trim sets the elevator position and the elevator position controls the AoA which controls the Cl which controls airspeed. (whew!)

Trim->Elevator->AoA->CL->Airspeed.
 
I had that thought once too.
I came up with spin out of the clouds or tie a shoe string to the mag compass and try a slow let down.
 
Spins though clouds? next you're gonna bring back lamp lighted air routes and goggles...


but... i never wanted to be an airmail pilot... :)
 
tgrayson said:
A level won't function as a level in an airplane, which is why we have gyroscopes. At best it will give you slip/skid info. Since that reveals the direction of lateral acceleration, it's conceivable that it might provide some bank information. However, slips can be caused by yaw, too, not just a banked attitude, so that instrument would have a lot of noise in it. I bet the pilot would very promptly have the aircraft in an unusual attitude if he tried it.

The pilot has no real hope of controlling the airplane in IMC without a gyroscopic instrument. Best bet is to take the hands off the yoke, begin a gentle blind descent, and rely on the airplane's dihedral to prevent too steep of a bank before breaking out of the clouds.
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True! I was trying to think of ways to fashion makeshift instruments with items I would be likely to have with me. I suppose one could also try to fashion a makeshift compass using the permanent magnet from the no longer working whisky compass and floating that in a liquid. It might wind up just sensing the aircraft structure, though.

Of course the scenario about total elec. failure on a moonless night without a working flashlight would negate my attempt, also. Not only would I not be able to see my bottle once I was done peeing into it, I probably wouldn't be able to even urinate into a bottle without peeing all over the plane and myself anyway!
 
Oh, you know what? There are some Iphone Apps out there that are supposed to work like an ADI. They aren't approved for flight, and not that accurate, but they might be better than nothing. (Personally haven't used any of them, so I don't know if they work, or how well).

Might violate sdfcvoh's intent with the scenario, though, since it seems like his scenario is based on a total lack of instruments of any kind. Pulling out an iPhone app is probably too close to using some kind of partial panel.
 
fish314 said:
Oh, you know what? There are some Iphone Apps out there that are supposed to work like an ADI. They aren't approved for flight, and not that accurate, but they might be better than nothing. (Personally haven't used any of them, so I don't know if they work, or how well).

Might violate sdfcvoh's intent with the scenario, though, since it seems like his scenario is based on a total lack of instruments of any kind. Pulling out an iPhone app is probably too close to using some kind of partial panel.
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Yeah was going to say if you had an iPhone with a GPS app, could use the heading information as a bank indicator - depending on the update lag, it would probably work fairly well. Could also use its ground speed readout to give you a rough estimate of airspeed, along with the sound of the airplane.

Interesting scenario to think about, just hope that never happens to ya, a complete failure of pitot/static, electrical, vaccum AND mag compass at the same time would be REALLY bad luck, :laff: Fate is the hunter!
 
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