ShoeString,
I enjoyed reading your comments about precision hovering especially the anti-torque roll. I think obtaining more precision in hovering is a very noble pursuit and one that will help better define what needs to happen design-wise to improve our current capability. The technical part of this, which you mention, cannot be overlooked (torque, spiral slipstream, P-factor, gyro precession, prop normal force) because combinations of these five propeller "evils" are the primary source of our lack of precision. You'll find it really interesting when you start hovering because you can see each one of these effects rear it's ugly head before you can counter act it with a stick input. Hovering is also an unstable situation and introducing some level of natural stability would help pilots better control the airplane in a hover but part of the mystique of the maneuver is it's difficulty. It's also one of the few flight regimes in R/C aviation where the inertial forces far outweigh the aerodynamic damping you typically have.

I realize that you didn't want to talk about the aero/S&C technicalities but there are a few things you may find interesting. Torque and spiral slipstream are obviously the big propeller effects that make hovering difficult and they are the ones that you have to deal with all the time. The others only get to be a problem when you start maneuvering such as in a "torque rolling square loop" that John Glezellis performed at the E-TOC...this was also a required maneuver at the prestigious Japanese Aero-pagent several years ago. The torque problem is simply a left rolling reaction equal to the moment required to spin the prop at a given RPM...it is well understood for the most part and other than I still hear most full-scale pilots say that torque is what causes one's airplane to yaw left on takeoff which of course is false.

Jon mentioned this years E-TOC which was the first time I'd ever seen the anti-TR used in actual competition. I'll point out some of the problems I had using the anti-TR. First, no airplane whose propeller spins in a single direction will be capable of equal sustained roll rates in both directions. I worked on increasing the aileron power of the Tensor design to just barely make the roll rate to the right equal to the natural torque roll spin rate to the left using no aileron input. While this gave the appearance that the rates were equal in reality when one combines the motor's torque and left aileron power the true roll rate capability is nearly double that of the anti-TR roll rate.

The spiral slipstream causes something a bit different than what you learn in standard flight school. My Tensor design which I used in the E-TOC had equal vertical fin area above and below the thrust line and therefore didn't need any right thrust to counter spiral slipstream but what I found interesting was that when I deflected ailerons to the right it would cause a nose down pitching moment and a nose up moment when holding full left aileron. Once the roll rate fully developed this pitching moment reduced quickly but nevertheless this is an interesting phenomenon whose asymmetry is a result from the slipstream rotating in a single direction. This effect had to be compensated by the pilot to make the transition from TR to anti-TR look seamless.

I've been working on hovering into a garbage can for a while now and I must say that it's extremely difficult task especially when you put a time limit on it. I find it much easier to hang the wheels on a basketball hoop than drop down into a garbage can.

As far as what's new and exciting in hovering I think that Mark Leseberg Jr. is doing some of the most amazing point-TR's that I've ever seen...very precise and timed to music. Point anti-TR are slow and boring right now in comparison and simply a waste of time until we can command a change the direction of the torque...these type of designs are currently in development. Right now hovering is still a very dynamic maneuver and I feel that as pilots we're simply hanging on for the ride for the most part but nevertheless I'm a true believer and I feel that one day we'll tame the TR and get to where we have full precise control over every axis.

Thanks for bringing up an interesting subject,

George Hicks
Team JR

BTW, Thanks guys for all the kind comments about the anti-TR