View Full Version : High Speed Wobble
Gary O
06-13-2006, 01:03 PM
I'm running a Tempest FAI set up and I have a wobble in my idle up RPM ranges. I'm using the 1:0.9 set up on the fly bar for max fly bar and min cyclics. I also have it set for neg delta. It's fine between 1500 and about 1685. Above that and it starts to wobble pretty good. I've tried everything I can think of and can't get it to stop. Any ideas?
DavidH
06-13-2006, 01:22 PM
What paddles you using and how much do they weigh?
David
Also, what dampers are you running. On the Tempest FAI head, the slower you want to run the head, the softer the dampers you need to run. I run four 50 durometer O rings and hover between 1450 and 1500 without a problem. At the end of an auto, when the speed drops off, I sometimes get a slight wobble even now.
If you are runnning a LOT of negative delta, it seems that you have better luck if you run heavier blades to keep the head stable at higher rpm. I run only 8.5mm negative delta and run 195 gr blades which seems to work OK. If you go to 20 mm of neg delta, the blades need to go up in weight to around 225 grams to keep the system stable.
Gordie
Gary O
06-13-2006, 01:58 PM
I'm running the X-Cell paddles at 40 grams.
Gordie, my problem isn't on the low rpm side, it's in the 1700 and higher rpm ranges is where I'm running into the wobble problem. I'm using a 70 and 60 duro dampner in ea side of the head. I had 60's all the way and tried the 70 to see if that helped but it didn't change it. I also went from 720 V's that were 195 to Radix 710's and it didn't change anything either.
DavidH
06-13-2006, 02:08 PM
I have never used 70 duro dampeners in the FAI head. I have used 50/60 and 60/60. I like the 60/60 as it gives me a little more crisper aerobatics. But I have to bump the rpm up in hover to keep it from wobbling.
1500-1525 rpm hover
1900-1950 rpm aerobatics
710 mm TG blades 195 grams
45 grams on the P3 paddles
5.5 mm negative delta
Gear ratio 7.75
David
Gary O
06-13-2006, 02:58 PM
I'm going out now to decrease the delta and see what that does. I'm thinking of leaving the dampner set up alone for now so I'll know if the delta is the problem. If I change too much at one time I won't know which one was causing it.
Gary O
06-13-2006, 05:13 PM
It's fine now. I changed the flybar ratio to 1:0.65 and it's rock stable in a hover at 1500 rpm. Idle 1 is 1750 and idle 2 is 1850 and both are smooth. I went ahead and left the delta alone the way it was. The aerobatics are actually better with the slower flybar and quicker cyclics and collective.