Turbine Heli in freezing cold?

[sunnyville]

Hi all!

A quick question: Do any of you have experience flying a turbine heli in subzero (Freezing) temperatures? I am simply interested in whether or not a turbine would have trouble starting for example or keeping constant RPM, etc. I have no turbine experience as of now, but that may soon change!
Your answers are very important to me, so thank you in advance!

[Skiddz]

I don't think the engine will care as long as the bearings aren't frozen solid before trying to start up, but you may have a problem with fuel freezing up in the tanks..

It would probably be a good idea to keep the heli in a warm car until just before you're ready to fly.

I don't know what the gyro (or flybarless controller) might do without it "aclimating" to the difference in temps tho...

[sunnyville]

Ok, thanks. JetA is ok I think till -49 Degrees C. So i should be fine ;-)

[flymustangs]

I know I flew mine below freezing, probably down to about 20F. I did lower the max rpm to keep my head speed under control. That was much easier than adjusting throttle curves and had a similar effect. Of course, the governor solved that problem.

[sunnyville]

I'm guessing you're flying a JetCat if you have a governor right?

[satsuma]

Originally Posted by sunnyville

I'm guessing you're flying a JetCat if you have a governor right?

Could ALSO be a Jakadofsky as both makes governed, and both work very well indeed.

[ppridday]

I have flown my Wren 54 Predator in the winter in Minnesota and now down here in Alabama. It definitely is happier starting down here in the heat as opposed to 20 degrees F in Minnesota. Kerostart may help that though if you went with that option...

Paul

[sunnyville]

Originally Posted by satsuma

Could ALSO be a Jakadofsky as both makes governed, and both work very well indeed.

Jadakovsky have governors? Might pay them a visit, they're about 40 minutes away from my house.

[sunnyville]

Originally Posted by ppridday

I have flown my Wren 54 Predator in the winter in Minnesota and now down here in Alabama. It definitely is happier starting down here in the heat as opposed to 20 degrees F in Minnesota. Kerostart may help that though if you went with that option...

Paul

Are wren 54 still in production? I see a lot of Helis with that power plant but they don't seem to be on the wren site.

[ppridday]

Don't believe they are still a production item, but they have only just been replaced with the 44. Parts and servicing will still be available for quite some time. I think there is a good parts supply.

Paul

[DominicD]

Proof

[lperagallo]

Many of us are running Vbar and Skookum governors on our Wren 44s. They work quite well. As for running in the cold, they do run fine, but if you are starting with Powermax you have to be careful it doesn't freeze up on you. I always warmed the Powermax can by the heater on the floor to keep in warm in the car.

With the new Kero start in our Wrens we will have to see how easy it fires up. I suspect that it will be fine, but this will be my first winter with Kero start.

Lou

[sunnyville]

Thanks for the replies! I could see kerostart being am issue in the cold. So I look forward to your experiences with that this winter!

[flymustangs]

As Lou mentioned, it was a Wren 44. I was using the vbar governor on mine. It's predictive nature lets it work very well with the turbine.

[Luvmyhelis]

Originally Posted by DominicD

Proof

OMG! you guys are totally insane!

[MidLifeCrisis]

Sunnywille,

I'm still brand new to the RC Helicopter world, but I've vast experience with aircraft derivative turbines.

You should be aware that three things happen in extreme cold climates with a gas turbine of any type or size. (Aside from the typical fuel considerations, that is.)

1- Fuel efficiency goes down. Possibly by as much as 28% depending on the fuel, turbine design, altitude etc.

2- Maximum available shaft HP goes up. This is primarily due to lower inlet and outlet temperatures. It doesn't mean the turbine, shaft, compressor, labrynth seals or any other component of the turbine can actually handle the extra available power without tearing up, but it can catch you by surprise if you're not expecting it. On some occasions your governor might be caught a little by surprise as well and it might hunt a bit.

3- Turbine flutter and stall can become more of a concern. Since the inlet air is more dense, so are the effects of turbulence. This in turn can make for harder starting.

The good news is- gas turbines are exceptionally well suited for cold weather climates overall- so long as they are maintained and everything is tailored to handle the cold.

Best of luck!
MLC

[sunnyville]

Thank you VERY much for that thorough answer! The higher turbine HP should not be a problem as teh SPH5-T has a built-in governor to keep the headspeed constant. At least that is my hope!
And obviously maintenance is important!

[flyinfool]

I do not have a turbine heli yet but my kero start jet plank with snow skis attached works great in the cold. The only difference is that the cool down cycle at the end of a flight is a lot shorter.
The only thing you may want to watch is that you do not spend to much time with the heli spooled up on a snow covered pad, I'm not sure if the snow particles are going to wear the compressor blades as they go thru.

[sunnyville]

interesting! How far below zero have you tried kero start? I thought that sticking with the old propane would be a safer choice as I could warm up the propane in my pocket/car and then start with the warm propane. I would think that the kero start heater unit (sorry don't know the technical term) would experience difficulties far below freezing (say -20C).