Silly question

[flyinfool]

Well OK maybe not so silly.
I know very little about turbines but do want one.

The impression that I have gotten from a number of posts has been that you can not add a Governor to just any turbine.

What is the difference between the output of a gov and the out put of the RX commanding a throttle position.

What brought this to my attention was a posting that a heli supplier is substituting a different ECU so that he can add a GV1, (or was the ECU change just to get Kero start)

I read so much talk about the ECU's other than the JetCat not having a Gov option and you must setup pitch/throttle curves and mixes.

Am I missing something here?

[cbergen]

First to answer your question, Yes you can install a gov into the Wren system, for a time Greg Alderman used a revmax in his Bergen Turbine.

Obviously you have to figure out some kind of RPM pickup, reading off of the clutch bell for instance.

I believe the real purpose there, as you mentioned, was to get the Kero start.

The question that I asked of this (Wren In the Bergen) system was, "Is the gov really needed?" In this system, the throttle curves are so very simple and basic to acheive extraordinary results, my answer is "NO!" :D

The proof that can be seen is in the videos, or If you happen to be at IRCHA, watch us fly. Watch the aerobatics, the inverted flying, the powerful takeoffs. In none of these flights will you see the need for a gov. The headspeed doesn't shoot all over the place through rolls, power on descents, or loops.

I suppose if you were flying at the absolute max power of the engine all the time, it might be helpful. But there is so much power available from this system, that we aren't even close to running it full out, I actually have the max RPM dialed way back!!

A gov does require programming, as do the throttle curves. I don't expect the throttle curves woudl ever fail, not sure about a gov or it's sensor....

[flyinfool]

I will be at IRCHA and hope to be able spend some time talking about turbines with you and others, maybe over some RumBalls. :mrgreen:

Your right there are pros and cons to everything.

If I'm not careful one might follow me home. :shock:

[cbergen]

MMMMM... Rumballsssss

You are a bad man!! :twisted:

Do you have a Turbine Waiver? If not we can do the test flight there with Gary and/or Greg, if so, I'll let you have a go at the sticks.

[rkeith2]

To echo Chris's response - my Bergen Turbine is set with the max rolled way back as well and easily dialed in throttle curves and it flies and behaves extremely well.

I have some flight footage in this silo if you want to view it.

http://www.keithranch.com/videos

Ron

[Heli_jack]

Ok, I think we are missing his question.

Pahl, Jadofsky, and the belt drive Jetcat along with probably a couple of others are gear/belt driven off the turbine coming out a clutch. Between gears and turbine speed you can dial in your head speed. With this type of setup, you just dial in the turbine rpm and run at that rpm all the time.

Wren, the two stage Jetcat, and maybe another, I am not sure, have a free running turbine with a scavenging second stage that uses the exhaust gasses to turn the second turbine wheel in the secondary stage. NO DIRECT CONNECTION, thusly, one needs to run a curve on this type..... Also AMA has a maximum head speed of 2000, which you probably wont even get near.

Now my understanding is that the Jetcat has a governor built in, and Wren does not. Those using the Wren have been having luck with the Throttle Jockey Rev Max. There is lag, all turbines lag. Not sure how much in those systems. I like my gear drive so far.

That in this condensed version I think answers your question.
Jack

[flyinfool]

Thanks all.
My question and a lot of others, are pretty much answered after IRCHA.

I think up more though.

[heliman53]

Ron, just wondering what do you have your max rpm set down too? I am playing with those numbers at present on my Intrepid and I am currious. Craig B

[rkeith2]

I am running the std 28 and 45 but top end is dialed down to 137,000

I also had to play a little with some other numbers to get a solid start up when cold and shorten the time from propane to jeta

[heliman53]

Thanks Ron, what kind of run times are you getting? Craig B

[rkeith2]

14:39 if I fly circuits in normal and a couple loops and rolls in idle 1 ...

[heliman53]

Sounds good Ron, I must be pretty close I am getting 14 mins and change on the TX timer and reading 16 or so on the ECU, I have maxrpm at 122,000 with 28 and 43 throttle curves are 32.0% @ 0 pitch 38%@ hover and 40%@ full pitch running 1500 head speed pretty much all the time. Craig B