RE: Stall Question
 

Ilikebipes-

There isn't anything they could have done. The washout just delays the problem a little for example. While that is good washout is a finesse application of a solution to get a little slower landing speed and optimize flow fields over the wing for something like a big cargo carrier. Washout to stop the hard snap that occurs when a lot of up elevator is suddenly applied won't do much, some but not much. The same for all the other things mentioned, they are finesse items, they might modify the break angle a few degrees but it will still break just as hard when it does.

It is just what airplanes do. You can do a lot of calculations and wind tunnel data and at the end of the day it is just something airplanes do. Pick up a rattle snake and shake it and it will bite you. It's just its nature. The same with an airplane and up elevator.

The best cure is to not do it.

RE: Stall Question
 

Mr Lanterman,
Thankyou for your reply(I seem to have taken over the thread, and I apologise.). Could you explain why left rudder has corrected the snap for me. I also notice that when Mike McConville pulls hard up at high speed into a hover, I can see the rudder move hard left. I've studied quite a bit of video from these guys and they all seem to do it as well.

RE: Stall Question
 

Schmleff,
No offence taken. Thankyou. I'd just like to help out someone else who deals with this issue, as much as you want to help. So- I probably get out of hand sometimes.

RE: Stall Question
 

I have owned three different funfly type planes. They were of the simplist designs. Thick cambered fully symetrical wings, with no washout/in or taper built into the wing. Increndibly low wing loadings, fiberglass boom fuse's. No matter how much elevator you dialed in, I never experienced a snap during loops.

I believe that is was due to simple aerodynamics that it was so predictable. Some aircraft are horrible. I have owned two Cap 232 one around 50 inches and the other one 85". Nothing I did helped them.

Build your aircraft as light and as straight as you can. Mixing a tiny amount of flaperons DEFINETLY helps. I am going to investigate this topic furthur, because I dont believe there is much information available for us modelers. I know that is the wing root stalls before the tip do, then you get a straight stall without any rolling tendancies. Therefore I think that if you use an airfoil with a sharp leading edge near the root, and blending in with an airfoil that has a very round leading edge at the tip, that should fix it. Hopefully one day soon, I will be able to give you specifics.

RE: Stall Question
 

Fun fly type airplanes tend not to snap for a few reasons, mostly due to the highly cambered airfoil and very round leading edge.

Interesting idea about changing the leading edge. You might consider some type of stall strip also.

It was found that by making an abrupt change in the chord of the wing near the tip caused the tip to keep flying longer. The F-4 Phantom used this method of preventing tip stall. Take a look at the wingtip of one and it is very easy to see.

Schmleff

RE: Stall Question
 

I have the exact same problem on my Lanier 1/4 scale Extra 300. I only got about 3/8" throw on the elevator and same thing, pull a little to hard in making a loop and it'll snap. It seams when you pull hard into a loop it snaps when it gets to about 45* and if you hold it there it will turn into a roll. Strange.
Does wing loading effect how quickly it snaps? A guy at the field figures it weighs about 15# and he said on a 72" ws it was too much and causing it to snap.

RE: Stall Question
 

Here's my oar in the water. I hope I'm not paddling in circles. I have had airplanes that snapped more easily with a forward cg. I attribute this to the fact that a forward cg makes you fly with more up trim to maintain level flight. More up trim increases the wing incidence to create more lift, etc. putting the incidence of the wing closer to the stall angle, making the airplane snap easier. I like the stall strip idea. Put a short piece of 1/4" triangle stock on the leading edge next to the fuselage, forcing the wing to stall there first before the tips can stall. Full size planes often use them, sometimes only 12-18 inches long. Jim

RE: Stall Question
 

Ilikebipes, Call me Ben, the other makes me feel as old as I am!!

My guess is that the airplane, due to all of the factors we have mentioned, and which is probably a nicely build and trimmed machine has the characteristics snap to the right. If it is dependable and repeatable then by using the rudder, which is not stalled, the yaw rate to the right can be stopped and keep everything straight.

I would like to experiment with one of these kinds of airplanes you mentioned. In a few flights we could find out a lot.

Most of my airplanes except my Cap are setup for the older big smooth style of flying and rarely get into the snap roll producing flight condition.

As time permits I will try the left rudder thing on the Cap through. It certainly is a good starting point. Good observation on your part.