Peter wrote:
Has this one (or an identical looking one) not been exhibited at Friedrichshafen every year since for ever?
Yes, that’s the one, and it looks like commercial availability has been “forthcoming shortly” for years…
Hmmm… 180kW=240HP so that is more like it.
Has this one (or an identical looking one) not been exhibited at Friedrichshafen every year since for ever?
LeSving wrote:
Looking at the numbers again, they just cannot be real at all. 100 hp up to 33k feet? At 3.5:1 “overall” pressure ratio, then at 33k feet, the internal pressure in that turbine is lower than atmospheric pressure at sea level. The pressure ratio has to be way more than 3.5:1 to get any sort of power out of it at 33k. Then maybe the pressure ratio is much higher at 33k, but only 3.5:1 at sea level? This could work I guess, but then the efficiency at sea level would be abysmal, an order of magnitude more fuel consumption than they list, and the turbine really only runs well at 33k. But, why on earth would a turbine meant for microlights need to go to 33k feet? 99% of the flying is done 5000 ft and below.This turbine makes no sense IMO. Looks to be vapor ware to me.
+ 1 !
Cobalt wrote:
the compressor (before the combustion chamber), which is probably the number you refer to.
Yes, on their site it does say “overall pressure ratio”. I take this to mean compressor pressure ratio. Looking at the numbers again, they just cannot be real at all. 100 hp up to 33k feet? At 3.5:1 “overall” pressure ratio, then at 33k feet, the internal pressure in that turbine is lower than atmospheric pressure at sea level. The pressure ratio has to be way more than 3.5:1 to get any sort of power out of it at 33k. Then maybe the pressure ratio is much higher at 33k, but only 3.5:1 at sea level? This could work I guess, but then the efficiency at sea level would be abysmal, an order of magnitude more fuel consumption than they list, and the turbine really only runs well at 33k. But, why on earth would a turbine meant for microlights need to go to 33k feet? 99% of the flying is done 5000 ft and below.
This turbine makes no sense IMO. Looks to be vapor ware to me.
.
Adam, all the ones I mentioned are EASA certified, only M601A and M601B aren’t.
Ultranomad – that is probably correct, but I don’t think many of the 601’s are certified in the west. I know a few are, but not all of them.
AdamFrisch wrote:
PT6’s and TPE’s an M601’s do well here, but they start at 600+hp. […] GE is expanding it’s H-series, so it’s not unlikely that something smaller will come from them in the future.
Actually, M601 does exist in versions rated at 315 hp (M601Z, with a separate drive for spraying/dusting equipment), 430 hp (M601D-11NZ, for Fletcher FU-24) and 540 hp (M601D-2) max continuous, but they all weigh 200 kg, same as more powerful versions. The GE H-series extends the M601 family upward, and there are currently no plans to make smaller ones, and in fact, the current Hxx-s are said to suffer from some unexpected reliability problems.
Some of the older Allisons (don’t remember exactly which ones) were designed for fixed-wing applications, too, though they may have been a bit over 500 hp. An Allison 250-C20B on RFB Fantrainer is 545 hp. RR300 and RR500 are essentially the same design.
Helicopter gas turbines are not well suited for aircraft as they have low thermal rating. This is why the P210’s, Extra 500’s and a few others lose their will to live at 16000ft. They just run out poop. PT6’s and TPE’s an M601’s do well here, but they start at 600+hp. There is a gap there for aviation grade turbines in the 250-500hp region. The RR500 was going to be the solution for that, but the development stalled for some reason. GE is expanding it’s H-series, so it’s not unlikely that something smaller will come from them in the future.
EPR is measured between intake and exhaust of the turbine engine only (excluding the pressure generated by the prop).
For a turboprop, it is desirable to be LOW, because most of the energy of the gas stream through the engine is extracted by the turbine that drives the propeller. Which is different from a jet engine, where is should be HIGH, because here the gas stream thrust is used directly to propel the aircraft. For turbofans, it includes the pressure generated by the fan.
This is different from the compression ratio of the compressor (before the combustion chamber), which is probably the number you refer to.
I have no idea why they mention the 3.5:1 number, as it is hardly relevant, and if it is even correct, though.
