Throttle curves on a turbine?

[DDragon]

Gary and Greg;
Did some attemped hovers in my driveway; i.e., just barely lifted off, and some skidding laterally, but feel sure the head speed was close to hover. I was so busy concentrating on keeping the bird upright, didn't think about a head speed measurement, but think it was around 1500 rpm. My son did do a fuel consumption measurement; used over 40 onces of fuel in 7 minutes. That seems a little excessive.

My throttle curve goes from 0 to 52% at mid stick, and from 52% to 53% from mid stick to full throttle (per Bergen's instructions). Pitch curve goes from -9 to 0 at mid stick, to +9 at full stick. At these settings the bird has PLENTY of power; the collective stick barely moved above center position at liftoff. Should I lower the throttle curve for better fuel economy?

Garren

This is a repost. But I thought I'd start a new thread because I'm curious now. I saw this an old message and was wondering about this and maybe someone can shed some light.

I thought that turbine helis didn't have throttle curves, and the speed of the turbine was control by a slider on the radio. So that you are either in idle or full throttle. But from the message above it seems that you can set the throttle curve the same as a regular engine (gas or electric) to control the headspeed? I'm assuming that you would the throttle channel?

BTW... how many channels should you have for a Wren turbine? 7 or 9?

Thanks

Thanks.

[Sara]

On the Wren you need throttle curves.

Some of our competitors do things differently, especially with the single-stage heli engines, so that's probably what you heard.

Sara Parish
Wren Turbines

[DDragon]

On the Wren you need throttle curves.

Some of our competitors do things differently, especially with the single-stage heli engines, so that's probably what you heard.

Sara Parish
Wren Turbines

Thanks Sara, that's actually better for me. I think in terms of thottle/curve pitches. So the throttle channel on the receiver would be used as in a normal gas/electric engine?

BTW... do you need a 7 channel or 9 channel transmitter?

[cbergen]

You would need no more channels than if you were flying Gas, Nitro, Or electric. In the application of the Wren 2 stage, It does not require extra channels to facilitate starting, RPM settings, anything of that nature.

The ECU plugs into the Throttle channel of your Rx, That's it.

We do use throttle curves with this system, but in some applications, that throttle curve may be very flat, similar to an electric. In my case, my throttle curve in normal starts at 0, goes up to about 51% at hover, and the top of the curve at 53%. My Idle up is 55% at low, 53% at mid, and 55% at high. These may change slightly depending on temps and altitudes, but you get the idea.

Others have had luck running a more "normal" curve, such as you would find with a gasser.

It's not difficult to do, I can usually dial one in in 1 flight, taking headspeed measurements and adjusting the throttle curve accordingly. As I often need to be reminded, it is important for the ECU to "see" full power, which is how my "launch" takeoff got started...:)

[DDragon]

Very cool! Thanks for explaining it Chris. For some reason I'm making it more complicated that it really is.

Yeah, I was wondering about those launches :) They just seem to shoot up into the air!

[rkeith2]

The fast take off is usually met with the same sort of comment as this photographer in San Diego. My Bergen turbine is just a few minutes into the video.

Ron

http://www.circlecityflyers.com/kenadams500243.wmv