I know Bill has probably coverd this somewhere before, but I figured I would share.

After slamming my gasser around for a while, I got tired of overspeeding the head at times. I'm running the GV1 with the Stator Gator sensor. It was most noticeable during big push-outs to inverted where my headspeed would come up to around 1900 to 2000. I would need to either load the rotor system again or hover for 5 or 10 seconds for it to come back down.

I decided to try an experiment that seems to have really worked out nice.

My thinking was that, unlike a glow machine, the butterfly valve carb on the gas machines is not linear. It tends to have most of it's change at a nearly closed position and very little change from about half way open to full open. I figured the GV1 was having trouble with the minute adjustments required to maintain a good headspeed as I unloaded the rotor system.

So I changed my throttle linkage to include as much mechanical expo as I could get. This would give the GV1 better resolution at lower throttle settings and less at higher settings which in effect made the throttle much more linear.

During test flying the setup, I tried my best to overspeed the head. The GV1 was right on top of any change. The worst it got was a minor overspeed during big push-outs to inverted. The GV1 would almost imediately fix the overspeed though, very much like my glow machine.

This also changed my throttle curves from a "U" shape to a "V" shape which tells me that the throttle is now very linear.

Try it out, you'll like it.
Malorie

Life's a journey, NOT a destination.

Mal -

as always, excellent feedback! I re -read this and relaized you said mechanical expo! great directions too.

Malorie

By mechanical expo, do you mean, setting the ball link close to the servo shaft and setting Atv 140 both ways? Im lost with your explanation.
Thanks
Felipe

Mechanical Expo

I think by that she means making the servo arm "face" or point towards the throttle arm on the carb when the throttle is in kill mode. This way the servo has to move more in order to open the throttle to a working range and hence has more movement in the lower end to work with.

I'd like to hear Malorie's explanation but this is what I think she means.

-=>Raja.

You're right on Mal...

Coming from a fixed-wing gasser perspective, we noticed many years ago that at about 50% opening you're often reaching upwards of 75-80 percent max RPM.

The Big Wally

Raja,
Your right on the money.

I set my arm on my servo so that at full closed throttle it is pointing nearly straight down the linkage and a full throttle it is pointing just past 90 degrees. Then I set the arm on the carb so that at full closed it is at nearly 90 degrees and at full open it is pointing almost straight down the linkage.

This way at near closed position the servo has to rotate quite a bit to get little rotation from the arm on the carb. At near full throttle the servo only rotates a little to get a lot of rotation from the arm on the carb.

This setup really make the gasser act a bunch more like a glow machine as far as throttle curves go.

Have fun, I really like this setup.
Malorie

Life's a journey, NOT a destination.

Malorie:

Thanks for clearing it up. I will give it a try.

Felipe

Malorie,

I assume you had to reset the gov right? As in the high and low on the throttle limits?

And I am not clear on the ball position, did you change that or just the arm postition? You would have to reset the end points right?

Thanks,

Scott

.
Great tip, Malorie! I'm gonna do just that.

.

Flying helis since gyros had springs.

No need to change the ball position on the servo, and only minor endpoint adjustments should be needed. The length of the linkage may need to change a bit, but only by a few mm.

Best of luck,
Malorie

Life's a journey, NOT a destination.

Thanks for the reply!

I will try that this weekend!!

Scott

How's this working out for you guys?

I just got back from the Joe Nall where I didn't get much of a chance to run the Gasser. Was just wondering how this setup is working out for those that have tried it? From the one short flight I did get on my Gasser at the Joe Nall, it seemed to still be working out great on my machine.

Any updates?

Malorie

Life's a journey, NOT a destination.

I did it!

I know this post is old but I'm new to the Bergens and I just discovered this post.I was having throttle setting issues.I was hovering around 25% and the head speed was high as well.So I looked at Malorie's gallery at the throttle diff set up.I set mine up just like it.I am happy to report that this has worked great.I'm now hovering at 50% on the curve and head speed 1520.SO as far as I'm concerned Mal's little trick work awesome for me.Thanks
Mal.

Nice find! I am also going to implement this.

Just remember

I takes a little work but well worth it.Just remember to start with a fresh linear curve in all modes and sub trim zero.You will have to reset your starting and idle positions, reset your False safe position,and throttle hold.After that head to the field and test hover.If you are not using a GOV.set your head speed where you like it then work on the idle up curve.Mine flies like a new bird.
later
Good luck

Gasser Throttle Link Setup

Anyone who isn't using this setup is really missing out. I've just changed to this setup after seeing this resurrected post,and I have to say that nothing I've tried has made such a dramatic difference.I've fallen back in love with my gassers.They no longer seem to fly "heavy",but rather just like glow powered helis without the mess and hassles!

IS THERE A PICTURE OF THIS SETUP? I don't understand from the description.

Check out this diagram. This is pretty much how I have my throttle set up on my G26 gasser

Gas is Great
Camper Fuel is Better!!
QWW Helis

I've been reading this thread since 2004 and honestly I still don't get it. Even from the Revlock manual they recommend something quite similar but I do not understand that either . Please do not try to explain further, I am definitely hopeless . From the picture above for example, how can the throttle arm move slower at idle and faster at full throttle (isn't a servo speed constant?) is beyond me.

Link copied from Malories Gallery if you missed it.

Zone...Constant speed of the servo isn't what we're looking at here. Its the length of travel associated with the angle of the control horn and the control rod. The control rod moves the most when its 90° to the servo horn. Hopefully the pic from Malories Gallery helps clearify it.

P-Gasser Se, Raptor 50 Se Hyper, Raptor 30v2, Trex450se, 3dx450...