What exactly is a snap roll and/or snap turn and how do you do one? (and why?)

Thanks

Hey chemie
where is the middle of MI. I'm in the southern part.

It is a roll where one wing is stalled. The lift imbalance causes rapid rotation. Some aircraft are designed with airfoils and control surfaces which encourage this.

You would do this at mid to high speed by raising the nose then applying opposite ruddder to the aileron input. Some models will do this easily others will not do it at all. It helps to have a rearward CofG.

WARNING THIS IS A VIOLENT MANOUVRE AND CAN BREAK MODELS.

I have to disagree with this statement. To do a positive snap roll, the rudder and ailerons move the same direction with the application of elevator. Only when doing outside snap rolls (with down elevator), do the go in opposite directions. Another thing is to unload the elevator one the rotation begins. This keeps the stall from going too deep and helps maintain flying speed after the snap. Unloading the elevator means to release part of the elevator throw that started the snap.

Many models will snap roll with just the rudder and application of elevator.

The other thing is the entry speed. Rudder manouvers are more effictive at slower speeds. While you can snap at full throttle, you will find that most models do them better at half throttle and it also limits the stress on the airframe.

Also what we call snap rolls are called "flick rolls" in England.

Now if you want to do an interesting variation of the common snap roll, try doing them from Knife Edge flight. Half a snap, full snap or a snap and a half are possible with practice getting the timing right. The difficulty is the recovery, as model will want to fall into a spin if you don't establish flight on it's side before putting the rudder back in to hold knife edge.

snap rolls are how you lose wings lol

They are common in IMAC and pattern sequences. Getting them to start and stop on line can be a real challenge, but very fun!

I always like to snap roll at the top of a loop. From there i can either finish the loop or fall out into a spin. When done properly and cleanly, they are very impressive maneuvers. I have always wanted to do a loop with a snap 1/4 up, at the top, 3/4 and at the bottom. I imagine this would be a very hard maneuver to do, but i think it would look sweet.
If you are just learning how to do them, start at half throttle, and with lots of alt. worse case scenario, you over rotate and end up inverted and heading for terra firma. Once you get them down, try and do 3 or 4 in a row. Its very hard to do right, but it looks great. I just love stalled maneuvers.
when i try new things with a snap, i just use full elevator and full rudder. It slows it down alot and makes it easier to end the snap where you want. Most full scale planes dont use aileron to do this, except the edges and yaks, ect...
Snapping this way also makes you loose almost all of your "E" at one time, so you need quite a bit of power if done in a veritcal maneuver.