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FT Delta Torque Roll or CG Issue?

#1
Hi, first post here. I just built an FT Delta and the maiden flight went very bad. As soon as it would leave the ground it would roll really fast. I thought maybe it was a torque roll issue so I'd cut the throttle and try to glide it back down, but it was impossible to control and would just crash over and over. The control surfaces looked good, I even dumbed them down to a little bit less than what the included control surface gauge recommended. I'm still a beginner I think but I have had several successful flights on my eflite inverza 280 and 47" value hobby sabre so I'm not a total newbie. I triple checked that none of the controls were reversed, and also kept checking the CG and it seems to be spot on according to the etched +'s on the speed build kit. However the power setup is an 8.25 x 5.5 prop on a park 370 motor with 10A ESC and 3c 1000mah battery. Which is pretty beefy for an FT Delta, so could it be too much power and causing torque roll?

Thanks for any help.
 
#2
That's a lot of weight and a lot of motor for an FT Delta. If you feel like building more I would build a bloody wonder with that setup and see how that goes. I uses a similar setup on the bloody wonder and the FT Flyer without much trouble. Are your trims set and everything is straight and level on the elevons?
 

Ace2317

Senior Member
#3
Did it still try to roll when you cut the throttle? One way you could test this is by giving it a toss (nothing too hard, but enough to get some lift going over the wings) and see if it tails off one way or the other still. Also, do you have your battery mounted in the center on the power pod? If so, it shouldn't be a CG issue because there should be about the same amount of weight on both sides.
 
#4
That's a lot of weight and a lot of motor for an FT Delta. If you feel like building more I would build a bloody wonder with that setup and see how that goes. I uses a similar setup on the bloody wonder and the FT Flyer without much trouble. Are your trims set and everything is straight and level on the elevons?
Yep I made sure the elevons were flat and centered. I got the 3 pack so I also have a Nutball and FT Flyer to try, but I was thinking the park 370 motor would be even more overpowered on those because they have smaller wingspans, would it be better on the FT flyer?
 
#5
Did it still try to roll when you cut the throttle? One way you could test this is by giving it a toss (nothing too hard, but enough to get some lift going over the wings) and see if it tails off one way or the other still. Also, do you have your battery mounted in the center on the power pod? If so, it shouldn't be a CG issue because there should be about the same amount of weight on both sides.
I think it did roll but differently. With throttle it was spinning like it was attached to a power drill, without throttle it was just all over the place, rolling and looping even though I had very small throws set and was using small stick movements. Maybe I messed up the CG? to get it to balance on the indicated balance points I had to put the battery pretty far back on the power pod, about an inch from the very back.
 

Ace2317

Senior Member
#6
I don't think it's CG. I can't know for sure without pictures, but I think it's one of two things.

1. It's out of trim. On a delta wing, your only form of leveling is the elevons. Whenever you power up the plane, look at your control surfaces. Are they both sitting level? More than likely you will actually want a little bit of right input (the right elevon be just a little higher than the left) to counterract the torque of the motor. Not much at all. Just a hair higher.

2. There is more lift on one side of the craft than the other for some other reason. It could be that the wing is a little longer on one side, the KF step is a little higher, or there could be drag somewhere on the lower side.

Which way was it rolling, do you remember?
 

IFlyRCstuff

Flyer Of Many Things
#7
All has been said. I have a unlikely theory. Your mix is backwards. I am presuming that youmchecked, but if up elevator on the stick is left or right roll, then that would influence it. Not likely though, but check
 

Ace2317

Senior Member
#8
All has been said. I have a unlikely theory. Your mix is backwards. I am presuming that youmchecked, but if up elevator on the stick is left or right roll, then that would influence it. Not likely though, but check
That could be it too. If they're flipped and you're trying to pull up, it's giving roll input. Definitely check that if you haven't already.
 
#9
That could be it too. If they're flipped and you're trying to pull up, it's giving roll input. Definitely check that if you haven't already.
Ooh! Yep you may be on to something. I was SURE they were flat to begin with because I used a ruler when centering them so they were perfect. But when I went to fly I noticed the elevator was backwards (forward stick pulled the elevons up instead of down) so I quickly reversed the channel and figured it was good to go. But I didn't really check anything after reversing it, just that the elevator input made the right result on the control surfaces, I didn't check if they ailerons were correct, since I've never set up mixing before it didn't occur to me that they may have been affected. I know they were correct in the beginning but I should have checked after reversing. I will check that, and also adjust for roll too. Thanks for the help! I might also use a 2 cell battery instead of 3 cell so it doesn't have as much weight and thrust for the 2nd maiden.