Large Model Association Forum

Hi All

I'm planning a new turbo-prop project ( Westland Wyvern ) - see "Technical Help" forum for further details.

Would be interested to know if anyone has experience with any of the current commercial offerings - Jetcat, Wren etc ?

Also, I'm aware of a few 'home-built' turbo projects on Youtube - any further info', advice, etc. gratefully received !

Dave C

Hi Dave,
yes I have a Wren 44 turboprop, had it 4 years now with no problems, its been in 3 different airframes, a Graupner Taxi 2400, then a Topflight 1/5 scale Mustang and currently a YT Cessna 188 Agwagon. Any questions just ask.

Barrie

Hi again Barrie,
Just a few questions at this stage : any experience with running the jet pipe exists down the inside of the fuselage on any of your above models ? (The JP exists on the Wyvern are just above the wing trailing edges for true scale effect). Secondly, what's the largest prop size /no.of blades you've run so far with the 44 unit ? I'm also wondering about fuel weight /consumption - at 1/4 scale, I'd like a flight time of around 15-20 mins but, with keeping an all-up flying weight as close to 25 Kgs as possible ?
Cheers for now,
Dave C

Hi Dave
I usually run a 24x12 prop 2 blades which works well but have tried a 22 x 12 3 bladed as well. Consumption is about a litre in 8 mins. I don't think running the exhausts inside would be a problem as they are only half as hot as a pure jet at around 300c.
Barrie

Cheers Barrie - very helpful that. I'm now in touch with Mike Murphy (Wren Turbines) and Dave Wigley of New York (designer/builder of the 1/5th 'S4' prototype that won Top Gun). Also, Phil Clark (Fighter Aces) has offered help on the materials supply side. On the fuel front, do you get any trim change as it's used up, or, is the tank right on the CG maybe ?
Dave C

Yes Dave tank is almost on c of g and there is so much room in the cessna that the 1.5 litre tank is easy to fix anywhere, you will not have that luxury I suspect! I still have to smile every time I start the turboprop how it just winds up slowly to idle but never enough to move the plane. Getting the correct revs to taxi can be a problem, but having spoken to a pilot of a full size T/P they have the same problems.
Barrie