Hi,

I would like to set a snap roll mode besides the precision mode I already have. Do I have to set larger throws just on ailerons or on all channels (rudder, elevator, ailerons.)? I increased slightly the aileron rate but could not perform fast knife edge to knife edge snaps. My model snaps a little bit slow, on avalanches for example I can not get a clear snap roll it looks like a normal roll.

Should I increase the rates, move my CG further back or both may be?

Thanks in advance,

Nick

More rudder and more aileron make the snap faster, with rudder making the snap more stalled and producing a larger cone. More elevator slows the snap, in my experience, and makes the snap more violent, with the plane's CG moving around more.

My snap mode has lots of rudder and aileron (more than I use at any other time), with medium elevator (more than normal flight but less than a spin). My control input is usually to slam elevator and rudder, then slam aileron and take out almost all of the elevator.

I'm sure there are other ideas on snap throws and technique, so try them all.

Nick,

I set up a condition on my Tx's elevator stick. When I give it full elevator, it increases the throw of the elevator and aileron, but decreases the throw of the rudder.

You do need a decent amount of rudder throw, otherwise, you won't see the pitch but just a fast aileron roll, and you willget a zero for that.

Adrian

Yassou Niko,

It depends on model design to a large extent as to what throws are needed and when. If your stab is about 22% of the wing area, then elevator throw would need to be less than if the stab was about 24-25% of the wing. That's to enter the snap. Then follow quickly with moderate (medium) rudder and then as much aileron as you have at medium rate, in that sequence.

As the stab gets larger, more elevator is needed to effect the initial stall followed by considerable amount of rudder to rapidly stall one wing; then high aileron.

Some planes that have really big stabs (28%-30%) are much more difficult to snap easily and have the models exit on line. More of everything is going to be needed for such designs, and the trick will be to lead the exit, so it comes out of the snap somewhere close. Much more rudder finnesse is needed with these and they are more prone to over-rotation. Conservation of momentum is often compromised with such designs.

There is a key design parameter called the TVC (tail volume coefficient) which is a ratio of stab to wing area multiplied by the ratio of tail moment (wing AC to stab AC) to MAC (mean aerodynamic chord). The easier flying models have a TVC in the .65 to .75 range but you won't find many in that range. Many are in the .85-.95 range and some are at 1.

As TVC increases, so does the pitch stability of the model. If you want a spritely model in any flight condition, keep the TVC somewhere around the lower numbers.

Kai ego gennithika kai megallosa stin Ellatha, stin Athena.

MattK