I have a Limbo Dancer that has plenty of power for 3D as well as plenty of throw in the control surfaces. However, when I position the airplane in torque roll/hover position, the rudder has apparently very little authority, even though it has plenty of travel (50 or 60 degrees each side) and is apparently large enough to kick the tail around. Whenever it starts to fall of a hover, I kick in some rudder and it simply doesnt seem to make much difference. BTW, I am using high torque servos on rud. and ele., so, lack of torque is not an issue. It feels to me that the prop wash doesnt reach the rudder as the rudder may be too high so it isnt in the path of the wash. does it make any sence?
I have seen several pics of people hovering their Magic, which to me, looks a lot like a limbo dancer. In fact, I wouldnt be able to tell the difference between them.
Why is that happening?

Thanks

How far aft is the CG?

What type of engine?
2 or 4 cycle? I am willing to bet its a 2 cycle.
Nothing wrong with a 2 cycle for 3D on these types of planes however, a four cycle produces much more prop blast over the tail because they can swing a larger prop.
You may be right in thinking that not enough air is getting to the rudder at High Alpha. (3D)

I'm not that familiar with what a limbo dancer looks like. Do you have a pic?

The CG is about 1/2 inch behind balance point.
Yes, I have a TT46 pro with a 12.25/3.75 APC prop on it. It has anough power to hover at 1/2 trottle.
The pic bellow is not my plane but thats how it looks like. You cant quite see the distance3 between the stab and the rudder, but on mine (per plans) there is about 1 inch gap between stab and rudder.
Thanks

It actually looks like it has more rudder area than my magic does, or it might just be the picture. It might also be a bit further forward that the magic. It sounds like you have the cg a little forward. With the 46 in the nose, you have to counterbalance alot of weight and force at the tail to overcome it. Can you move the battery pack backwards some? I noticed that my magic has awesome rudder authority at lower speeds, but is terrible at higher speeds. If your balance checks out ok, then check for any slop in your linkages, or actual flexing of the vertical fin and rudder. Try putting on some small tail wires, I used .024 music wire, and 4/40 screws with aluminum washers between the wire and the wood, and went all the way around. The #1 complaint I have read on the magic/limbo dancer tail setup was that they flexed under large deflection. I could see where that was going to be a problem on mine, and put the wires on right from the getgo. How much throw do you have, low/high rates, and total throw?

If all else fails, build a larger rudder, and angle the lower rear portion, to clear full elevator deflection. Try adding 1inch or so, maybe 1 1/2 inches. You could build that out of solid sheet balsa if you have lead on the tail, and remove some of the lead.

Good luck,
Steve

Everything I've got that can hover from a Sudokhoi turning a 12x3.75 to an extra 260 turning a 27x10 would probably feel to you like it "doesn't have enough rudder authority when hovering". My Sudokhoi hovers easily with the 12" prop. I don't feel any need to go buy a 4 stroker that'll spin a 14" prop.

What other planes have you tried to hover? Do they feel like they have enough rudder authority for you? Two things to remember when hovering. 1) You're balancing the plane. Once it falls off very much at all it doesn't matter how much rudder or elevator you have it'll need a kick in the tail to right it.
2) You can quadruple your surface authority by flooring it while providing your rudder or elevator input.

The trick to hovering is to learn how to keep the plane balanced. If you see it start falling off then try and catch it, you will be too slow. If it always falls off to the right, know this. Keep some left rudder in it all the time until you get it to start falling off to the left. Then decrease the rudder input. Repeat.

Oh, and I don't find the CG makes diddly for difference when hovering. Put a weight on the end of a stick and balance the stick on your finger. If the weight's 20" away or 20.5, it's still damn hard to balance.

Steve,
The limbo dancer has as much throw on high as it has on low. The only difference is that I use positive expo on high and neg expo on low. Thats because even on low for taking of and landings, I want to know I have plenty of throuw in case I need. Besides, I like to go from an usual flight to a 3D flight (spins and such ) without having to flip the switches. Then I flip them up for torque roll and hovering only. Just a way I feel confortable with.
I was checking today and It probably has 60 or 70 degrees to each side from center. This is probably too much as it is probably acting as airbrake. Ill bring it down to 50 degrees or so. Ill probably have to move the cg a little aft. in fact, It has some nose weight to balance it. And steve, ill probably follow you advice and install some wires to keep the fin from flexing as well as keeping it from breaking.
regarding the slop in linkages, thats I am sure is not an issue as I am using pull pull for rud and ele and they are pretty tight.

barryb
I can hover my sig ultimate funfly for a good 30 seconds as well as my bearcat funfly and the rudder definitelly has plenty of authority as it will respond to any rudder input nearly instantly.

I use some POSITIVE (around 20%) expo on ele and rud on high rates and about 40%neg on low. Same throws on high or low rates.

Thanks again

Sounds more like your behind the curve...in other words..your letting the plane get too far off center before the recovery is made...also an 11/4 zinger wood seems to be the best performer on the TT 46 pro....just my opinion...hope it helps