Difference in roll performance
 

Hello all,
I’m still new here so be gentile…. I’ve got a H9 raptor, and though I know it not the greatest sport plane ever, I just wanted to know if it is the airframe or something else causing my issues. I’ve noticed when I perform a roll, there’s a difference in what the tail tends to do. If I roll to the left, rolls are axial and no funny business. However, if I roll to the right, about 90deg into the roll, the tail starts to swing ahead of the fuselage, kinda like a crappy snap roll. I have checked all the control surfaces, and all the throws are identical from left to right. Is this a thrust angle issue, and if so, what would I have to do to correct this?... More LT thrust? Just a thought, if I'm headed in the wrong direction, pleas let me know.

Any inputs are much appreciated

RE: Difference in roll performance
 

You may be inadvertently adding elevator. I know i did that a few times when i was learning

RE: Difference in roll performance
 

Hmmmmm. Have you balanced the model laterally? That is, tied with a string around the prop shaft and between hinges of the rudder it hangs level along the centerline, without one wing dropping consistantly before the opposite side. You should also carefully measure from wing-tip to the top of the vertical stab from both sides and make sure that measurement is equal.

You can correct some barrel-roll tendancy with differential aileron mix (more up than down throw) but the tendency for the tail to advance on one side is new to me. You've built Lomcevak into it somehow! Neat trick!

Does the tail swing to the inside or the outside of the roll? If the tail droops towards the ground it is reacting like it was extremely tail heavy. That, or the rudder & vert stab alignment is unequal and it is tucking one side once it has rolled enough that the rudder is providing lift (or anti-lift). Check the incedences of ALL the fixed surfaces and not just the control surfaces.

RE: Difference in roll performance
 

I agree with the above that your either unknowingly control mixing, or your airplane requires additional control trimming.

RE: Difference in roll performance
 

Lateral balance - Check - No weight required

The plane is a tad nose heavy (helps with ground handling), but the c/g is well within the recommended limits

The tail swings into the roll. If I was to measure it somehow, it looks as if the tail is making a 1ft circle while the nose stays centered.

It just seems funny to me that it only happens when I roll to the Rt. If I am adding elevator, then crap, I'm the dummy! But anyhow, when I get a chance this evening, I’ll measure the distance from wingtip to the tip of the vertical stab and see what I get. Also, I have attempted to knife-edge this thing, it won't hold it, but the nose drops off at a pretty consistent rate either Rt or Lt, no difference in the sink rate or habits. This plane doesn't like rudder as it is, and I try to stay away from it unless I need to crab for a crosswind, and when I do use it, I better be ready with opposite aileron to compensate. Rudder alone will flip it on its back in a heartbeat, so I can’t give any better info on any rudder habits, sorry.
Thanks for the info fellas, Spit

RE: Difference in roll performance
 

OK, measured the distances from wingtip to vert stab tip on both sides, and they're within a 1/16'' or mabye a little less of each other. Need some new ideas....

RE: Difference in roll performance
 

The real simple solution is to get an experienced flyer at your field to fly the plane. That will eliminate pilot error from the equation and an experienced eye may spot the setup problem fairly quickly.

RE: Difference in roll performance
 

Double hmmmmm.

Oooooo. I looked up the Raptor and I take it you have the F-22 Raptor model? All bets are off. That has two outwardly angled vertical stabs and a single prop. You're probably getting the vortex of the prop wash on one vertical surface and not the other, which might cause it to react differently depending on the roll direction. It may never roll evenly with a tractor prop. If one stab is out of alignment with the other, or the engine has offset, that would further complicate a smooth roll with two large stabs. I believe some of the WWII German bombers and night-fighters that used twin tails had some problems in handling, also.

If you're also using the plastic "droops" it further messes with conventional model aerodynamics.

May be worth noting that the modern fighters are "fly-by-computer" and not just fly by wire; as the basic designs are unstable enough that a human can't fly them on training and instinct alone. I'm sure Hangar 9 modified the airframe to be suitable for R/C. But perhaps not suitable for FAI pattern.