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View Full Version : Collective POP is gone

povern
02-27-2010, 08:13 PM
Running a Protos with the 360, 9650 (4.7 volts / 16mm from center) at 2600 HS.

When I do pitch pumps they are very sluggish, when I do pitch pumps on the FB protos at 2400, with HS-85 (non- digital, 4.7 volts, 16mm from center) they are very sharp, heli stops on a dime.

When I still had my Flybar on the FBL Protos, it too stopped very crisply, add the Skookum and Blah.

Any thoughts?

povern
OnTheSnap
02-28-2010, 01:40 AM
Same collective pitch in both cases?
Slyster
02-28-2010, 02:08 AM
Same blades?
povern
02-28-2010, 08:07 AM
Yes and Yes.

Forgot to mention this is with a Skookum unit, not V-Bar
MrMel
02-28-2010, 08:30 AM
Reversed thrust bearings in the head?
cbergen
02-28-2010, 09:51 PM
How did you modify the head or what head did you put on it?
povern
03-01-2010, 06:34 AM
I went from the Stock MSH head, to the stock MSH FBL head. Same dampners

I before I installed the MSH FBL head, I had the RJX FBL head for the Trex500. There was no POP with that haed eighter.

It is like there is something in the Skookum that is limiting the speed of the collective movement in the head.
Slyster
03-01-2010, 09:02 AM
Vbar you can set the stick responses to "Slow, normal, aggressive and Hard 3D" etc.. is there something similar on Skookum? Sure made of difference for me when I went to Hard 3D... now this isn't agility or how fast it rolls and flips... just stick response... they are seperate things.
povern
03-01-2010, 10:02 AM
Through the Elevtaor and Ail gains you can speed them up, but there is not an overall "stick speed' setting.
Wazzer
03-01-2010, 11:37 AM
Definitly sounds like a Skookum Setting

have you tried starting from scratch with teh Std Skookum 3D profile?

or just comparing the two when you are Offline?

Just a thought
rickn816
03-01-2010, 12:52 PM
I went from the Stock MSH head, to the stock MSH FBL head. Same dampners

I before I installed the MSH FBL head, I had the RJX FBL head for the Trex500. There was no POP with that haed eighter.

It is like there is something in the Skookum that is limiting the speed of the collective movement in the head.

I don't know that we can figure this out without hands on the heli.

My TRex 500 had an SK360, and the collective was faster than I could imagine. :YeaBaby:

I actually reduced the max collective pitch just so I could keep it in view.

Rick
Wazzer
03-01-2010, 01:02 PM
Have you checked your full pitch range in setup mode?

You may need to adjust this with swash percentages maybe?

Ben
Flexis
03-01-2010, 01:08 PM
You might get some more pop by editing your pitchcurve. V-bar for example has servo geometry adjustment which is a bit like adding expo. You might need some negative expo to make the sticks more sensetive around center, or maybe you just need more pitch?

Another thing, flybarless puts more load on your servo's, so if your servo's are too weak they might slow down under the extra load.
Penguin
03-01-2010, 02:24 PM
I had Skookum360 on my Trex 500 and when I switched from trailing edge main blade control with positive delta to leading edge blade control with negative delta, I noticed a significant decrease in "Collective Pop". I didn't like it at first but I got used to it and eventually felt more in control.
povern
03-01-2010, 06:23 PM
I starting to lean towards weak servos (9650) and lack of collective management.

Maybe when I get my third Protos up, I will move the FBL unit over to that one. and see if there is a difference.

Until then I use the FB protos for collective POP and the FBL protos for everything else.
povern
03-02-2010, 01:33 PM
How about servo arm lenght?

Should I move the balls out past 16mm, that would speed up the throw correct?

povern
prototype3a
03-04-2010, 08:33 AM
Increasing the radius of the arm (moving the balls out) is a sort of trade off. When the servo is not working against any force, yes this would speed the movements up at the cost of precision. However, in the case of a cyclic servo and especially in FBL setups, the servo is always working against the forces transmitted down through the head and the swashplate. Torque is defined as force times the perpendicular radius to the line of action of that force. So, if you are concerned that your servos are not strong enough then you should move the balls in so that the servos do not have to work as hard to move the arms a given distance and can get there more quickly. Moving the balls out will force the servos to work even harder and probably slow them down too.

I hope this makes sense.
povern
03-04-2010, 11:04 AM
Makes great sense.

Changed my strategy, going to change the voltage to the servos to 6v, from 5v. (And put a step down in for the tail) and see what happens.

If that doesn't help, I may move the balls out on the arms a llittle.
Penguin
03-05-2010, 10:54 AM
Can you post a good picture of your FBL head showing blade grips?
Wazzer
03-08-2010, 09:55 AM
Makes great sense.

Changed my strategy, going to change the voltage to the servos to 6v, from 5v. (And put a step down in for the tail) and see what happens.

If that doesn't help, I may move the balls out on the arms a llittle.

Any News?

Did teh above help solve your problem?

keep us posted
povern
03-08-2010, 11:14 AM
Changing to 6V helped a little. Not enough to call it fixed.

I would like to post a picutre, but I totaled it this weekend. It was a stock Protos FBL head though.

In the rebuild, going to try different servos and some other items. Will try to keep everyone updated, but it is going to be a few weeks before this one is in the air again.

povern