aart wrote:
in a HW one always has obstructions
Admittedly moot point for the OP, but you and I can attest to it that not all types: there are retractable-gear, strut-less HW’s out there…
aart wrote:
A turbine powered VL3 and Bristell NG5, both ULM, are under development. Other than maybe the convenience of JetA I don’t really see the point. They won’t be economical in purchase price and running cost and won’t perform better than the high-end Rotax equipped ones I guess
GoGetAir are finishing off their turbine powered G750 for a client in Africa where the availability of other fuels except Jet A1 can’t be assured. The manufacturer advised that the aircraft will be exhibited at Aero and after that, handed over to the new owner. There is also a second benefit to the turbine – 3000 hours before overhaul; he indicated that the price / performance would be close to that of a 915iS powered aircraft (140HP turbine).
he indicated that the price / performance would be close to that of a 915iS powered aircraft (140HP turbine).
Turbine will use at least 2-3x the fuel, right?
GoGetAir are finishing off their turbine powered G750 for a client in Africa where the availability of other fuels except Jet A1 can’t be assured. The manufacturer advised that the aircraft will be exhibited at Aero and after that, handed over to the new owner. There is also a second benefit to the turbine – 3000 hours before overhaul; he indicated that the price / performance would be close to that of a 915iS powered aircraft (140HP turbine).
Since when is a Rotax 915iS a Turbine engine? It’s a small geared and turbocharged 4 cylinder engine and it cannot sustain 140hp for long periods of time, you would only use the full 140 for a short time during take-off. Also, there’s no point in trying to compare this engine typically used to power ULM/LSA aircraft and a Turbine engine. They simply aren’t comparable. There’s no point in trying to build a Turbine to power the same aircraft you would normally use a Rotax 915 for, the result would be disastrously uneconomical if possible at all.
LeSving wrote:
Technically the 915 has a turbine Perhaps it’s this little TP engine that’s meant for the G750 ?
It doesn’t have a turbine, it has a turbocharger, it’s a compressor, driven by the engines exhaust gasses it pumps more air into each cylinder, giving you higher compression ratios → (more power). It’s especially useful if you want to fly high, as the air gets thinner with altitude, with the turbocharger adding compressed air → your engine will keep working at greater altitudes.
A turbine engine is just a completely different type of engine, it has little in common with a Rotax except for the fact they both burn fuel and can power an aircraft.
The engine your link leeds to looks interesting. However, I don’t see anything regarding fuel consumption, so I have my doubts. Turbine engines have the advantage of having great power to weight ratios, they scale up well, but downsizing them never works, because the fuel consumption would be astronomical, you see there’s a very well pronounced boundary between where a Piston engine or turboprop makes more sense than the other. Piston engines have the advantage of having absolutely great fuel consumption rates, in fact the old piston engined airliners in the 50’s can rival present day jet powered airliners in that regard. But they would be way to heavy, maintenance intensive, and the planes would be slower etc.
A piston engine is really ideal for all small aircraft except military fighter jets off course. (There is a range where you can consider both a Turboprop and a Piston engine and at that point it depends mainly on what you prioritize and how big your wallet is, But then we’re not talking about 2 or 4 seater short range aircraft anymore. :) )
I my opinion if you really really want an engine of that size to burn jet-A, you should go for a diesel, like an SMA, Continental or Austro engine, or a straight converted automotive diesel engine. it’s the only thing that would makes sense.
Since when is a Rotax 915iS a Turbine engine?
It isn’t.
Steve6443 was talking about a turbine powered GoGetAir, not a Rotax piston powered one.
Turbine engines have the advantage of having great power to weight ratios, they scale up well, but downsizing them never works, because the fuel consumption would be astronomical
Exactly!
The jet powered Cri cri is testament to that.
The only way of getting any flight time is to push it to the threshold.🙂
Eagle20 wrote:
downsizing them never works, because the fuel consumption would be astronomical
I will differ… downsizing works. But not in the matter done since we can’t really speak about downsizing. Anyone looking into the inlet of a single stage mini jet turbine, which might be of radial or axial type, as to looking into the next airliner jet engine inlet will spot the differences. Fan size, fan ratio, multiple compressor/turbine shafts, etc. This stuff is more complicated than what is seen on these toy turbines, and would/will cost way more to replicate.
Then there is consumption. Airliners have very high consumption too, the more so on the ground (there were plans for towing trucks bringing them to the threshold on fields where delay is routine) and at lower levels. The cruising levels used, say the typical FL350-400, are not mainly chosen for comfort, but above all for maximum efficiency as in best miles/kg of fuel.
A mini turbine, such as used on the SubSonex has to be flown at higher levels too, probably >FL200, to reach some kind of efficiency.
We have a couple of interesting homebuilt projects here, to be powered by jet turbine… it will be interesting to see how those will perform.
Perhaps it’s 
