Airwolf Wobble :-(

[the-borg]

I have a Trex 500 with a Align FBL head and a Beast X that has been flying fine as a Pod and boom.
I put it in a RC Aerodyne Airwolf 500 fuselage but when I try and hover her it wobbles.
I replace the main shaft and main shaft bearings but I cant get rid of the wobble.

This is a short video of the problem
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Anyone had this problem ?

[DaveG]

More Headspeed required Scotty!!

More headspeed or softer dampers now you have the extra weight of the fuz, hard damping is not required.

[trexamanic]

where is the beast x situated now?
just wondered if it was causing any issue

[the-borg]

The Beast X is in the same place as it has always been on the block on the tail rotor gear at the back of the main frame.

[the-borg]

More Headspeed required Scotty!!

More headspeed or softer dampers now you have the extra weight of the fuz, hard damping is not required.

Would using Fly Bar blades have the same effect ?

[Mark Chaplin]

Hi,

As already stated try upping or lowering the head speed. You now have a resonance by adding the body. Increase or decrease the head speed to move the frequency of the resonance.
You said it was flying ok before adding the shell so I suspect this is the problem if nothing else has changed.
Hope this helps.

Mark.

[tomatwalden]

Have you tried lowering the cyclic gain (pot no. 1)

[French Paul]

Adjusting the cyclic gain will have the same effect as adjusting a flybar so no it wouldn't make a difference.
i would also up the head speed as everything has to work harder with the extra weight, and also read the beastx manual for adjusting the cyclic gain as its responding out of time.works the same as your tail gain, but for your cyclic control, and i think its adjuster no.1 on the unit from memory.
will be a cool little heli when you get it sorted!

[the-borg]

Hi all, I changed the dampers for softer ones (the old ones seemed quite soft any way) I also changed the Pinion to give me a higher head speed. Wend to a fly lunch time but it has made no difference .
So I will put it back to a Pod and Boom setup and fly it to check there is no issue the the mechanics.

[Smudgyboy]

You need harder dampers with flybarless they need to be rock solid.

[scallybert]

Have you tried lowering the cyclic gain (pot no. 1)

As well as being a very likely candidate; this is a quick and easy thing to try.

So, I can't think why anyone would try anything else first...

[the-borg]

As well as being a very likely candidate; this is a quick and easy thing to try.

So, I can't think why anyone would try anything else first...

I cant get to the pots where the FBL unit is so as part of putting it back to a pod and boom is to move the FBL unit to a more suitable place.

[French Paul]

I cant get to the pots where the FBL unit is so as part of putting it back to a pod and boom is to move the FBL unit to a more suitable place.

If that's the route you must take then an easy way to tune the cyclic gain before you put the fuselage back on would be to add the same amount of weight as the fuse to the skids.
just make sure the weight is directly beneath the mainshaft to keep the centre of gravity, also it is important to recheck the centre of gravity with the fuse reinstalled and baLance if necessary!
Also make sure all of your servos are set to 90 degrees because if they arent then the resolutions will be different and would also create these symptoms your getting.

[scallybert]

If that's the route you must take then an easy way to tune the cyclic gain before you put the fuselage back on would be to add the same amount of weight as the fuse to the skids.[...]

It might be 'easy', but it's not necessarily valid; and I'm not sure why you'd think it might be.

[French Paul]

It might be 'easy', but it's not necessarily valid; and I'm not sure why you'd think it might be.

Ever seen a fbl heli with heavy skids behaving the same way?
Each helicopter is designed to behave correctly within a certain weight limit, one of the reasons a battery weight is sometimes suggested as well as capacity limits.
Most just assume this is all to do with the actual size limits of the battery but it's got alot to do with keeping the machine within functional limits.
I'm guessing I'm totally wrong about this mechanical science.....?
A different weight hanging from the disc will take a different amount of time to react to the same input hence tuning the cyclic gain to react faster or slower.
If you still don't understand then go back to conkers, but stick a bowling ball on the shoelace, see how the reactions change.

You'll also see that most understand this simple science by only suggesting to lower the cyclic gain for the heavier forces.