3G Lift-off

[Bobs]

I have a 600N with 3G that flies good after lift-off (except for tail wag issues) but it's only a matter of time before the blades hit the ground when taking off. And yes, I've done the mod and it's the V2.1. After the blades spool up (Edge FBL) the heli tilts backwards until the tail fin hits the ground and then it leans to the left (the CG is perfect). If I make corrections then when it lifts off it lurches forward and to the right. Anyone got a solution for this problem? This is my second flybarless build. I converted a Vibe 50 over to Align's FBL head and 3G electronics and do not have this same problem. I also recently converted another Vibe 50 over to BeastX. Other than the fact it exhibits no bad habits, I'll reserve making further comments about BeastX at this time.

[Philluoma]

Redo the DIR setup and reset your sensor 'center'. Not sure what to really call it... But DIR mode teaches the 3G where nuetral is... Were all your trims centered in setup? Mine will spin on the ground without tilting til full spoolup, then lift off straight up. Mine is on a 500 ESP though. Sounds like a recentering or nuetralizing would help... Is the phasing of the swashdriver correct?

[1004ron]

I had my 550 behave similar when the head speed was too low at point where there was just enough collective to make it light on the skids - now with high HS well in advance of the pitch increase my lift off and landing is very stable.

[danyl]

Your 3G software allows for an adjustment of the "Swash Return". This controls how quickly the Swash returns to level when it comes off the skids. This could affect your problem, however it isn't the most likely. You could adjust it some and see.

The 3G is constantly correcting for unwanted movements of the body. The resistance of the ground against the skids is an "unwanted" movement. The rotor may be trying to pull the heli sideways or front to back, but before the rotor achieves lift, the skids resist the movement. The 3G corrects for this. Then, just as the heli achieves lift, the ground releases it's hold on the skids and the body swings, or pendulums into a new position. The 3G system must then correct for this "unwanted" movement by trying to return the rotor back to it's previous position.

The gain could be too high or too low. I am not certain which. Also your trims could be way out which is causing the heli to want to drift. Adjusting the "Swash Return" may fix some of the problem, but you may need to investigate for the source first.

[Philluoma]

Here's an idea... what's your pitch curve and throttle curve for normal mode? I run a dx7, and have a pitch curve in norm as 45-48-50-75-100... That way I'm not stuffing the heli down into the dirt during spoolup. Next thing I've got is a super soft start, and put the thro to midstick on spoolup every time... Then I wait for the motor to ramp up to the tx input... So the whole time I'm spoiling up I'm at zero pitch, or close...

[FrozenOne]

While testing different mounting solutions (pads, plates, zeal, 3M 3010) I had this happen to me. It was either vibrations due to the mounting solution I used or the sensor was slightly misaligned to the heli. The issue left with the mounting solution and has not happened since. Only the mounting was changed to induce and resolve the issue in my case. The heli flew ok in the air (some bad tendencies due to the mounting or misalignment) but would lean in a certain direction as the skids left the ground requiring corrections on takeoff.

[oppie]

On the maiden of my 550 I was very aware of the freak out on first lift off and almost lost it with a tip over but was able to lift off. I found I didn't have my blades tight enough and with a very soft start set up it almost tipped over. Next flight I tightened the blades and every thing was fine.

[K2Freak]

"While testing different mounting solutions (pads, plates, zeal, 3M 3010) I had this happen to me. It was either vibrations due to the mounting solution..."

+1

Same exact. Early on I had mine mounted with a single layer of Gyro tape (oops!) and it acted just like this. 3 tapes and a metal plate later it's really smooth.

[Bobs]

Thanks for all the suggestions but I've given up and ordered a BeastX to replace the 3G.