Spiral Instability

[3Dreaming]

Re: Spiral Instability

Any time we make a 360 degree turn with one of our airplanes the outboard wing will have to travel farther
(about 200 feet). With a .5 mile circle and the inboard wing tip traveling 100mph the outboard tip will be traveling 2.6 mph faster. The difference in distance and speed will vary with bank angle. The greater the bank angle the less the difference. Unless the airmass changes to match the turn of the airplane the outboard wing will also have to have a higher airspeed. Just like the propeller has a greater speed at the tip compared to the hub. The slip or skid will change the speed also, but only while the slip or skid is changing.

[flyguy]

Re: Spiral Instability

This is kinda fun. I love the student reaction to the stall and even more so when they start pulling Gs in the spiral.

http://www.youtube.com/watch?v=WWo-sryzQiQ

DC

[jim cooper]

Re: Spiral Instability

Jeffery Quill was the head test pilot for the supermarine Spitfire. He also flew MANY other types of aircraft as test pilot. One was a Wellesley. Over New Malden (in England) he relates: "I cranked the trim all the way up and let the Wellesley deaccelerate and stall. I then took my hands off the controlls and started to enter the indicated speed of the stall" (prior to this flight he had flown this aircraft many times in test and found it to be "Ladylike")" I was scribbling on my knee pad waiting for the nose to drop and she suddenly lurched into a right hand spin.". (He tried everything, gear down, full power, full flaps, etc. it just speeded up the spin.) " Finally he had to "Take Silk". The cockpit was IN FRONT of the wing so reluctantly he cut the ignition and "Took Silk." The airplane followed him for a while, narrowly missing him. It landed near a home. He landed in a tree in a backyard where a cocktail party was in progress and was invited in for a "Bracer". I hope some of you can get hold of this book! This fellow was something else! Interesting that the Spifire, in its evolution, went from about 1100 hp to 2400 hp mostly by 2 stage supercharging and better fuel to burn. (America had the better fuel.) The book is "Spitfire, a Test Pilots Story" by Jeffery Quill. (The Wellesley was a single engine bomber) Its a shame that the Taylorcraft did not evolve like the cub into something like the super cub, one with 100 hp, one with alot more. JC