Why no gas turbine engines in light a/c?

[gasax]

oh do pay attention people - The Extra - price $1.7M, I'll have a brace please - imagine how much cheaper with a piston engine?

The Kestrel - guide price £2.8M - oh I'll just have one then!

[AdamFrisch]

Half of that price is to greedy engine manufacturers!

[gasax]

Try chiselling a single crystal hot section turbine blade and then work out how much it actually costs. And then produce a couple of hundred.

You are much more likely to be abducted by aliens than be able to knock out a 'cheap' turbine.... Remember "the truth is out there". In many cases a very long way out there!!!!

[Charles E Taylor]

Why no gas turbine engines in light a/c?

None?

‪Glasair Turbine G-icbm‬‏ - YouTube

Charlie

[fireflybob]

thanks for all the posts and information - Charlie I love that Glasair one!

[Zulu Alpha]

I talked to the builder and he reckoned that over the engine life there was no cost difference between a 6 cylinder Avgas and a turbine. This took into account the initial cost, TBO, fuel and the higher speed of the turbine.

[gasax]

Given the performance of a turbine Glasair I suspect that tips the 'balance a bit.

From what I recall a RR250 is around $250k, the hot end inspection at 1750hrs is about $80k. An IO540 $65k - fuel at 60 lt/ht - say $150 in the Uk. So $260k in fuel for 1750 hrs, plus the initial 55 makes $325k. The turbine still works out rather more expensive - but the performance is very impressive. I've seen this aricraft fly and if I could I would!

Given the ability to climb near vertically the costs do seem to be worth it!

Better hope the tax on JetA1 does not increase - it would deprive us of some spectacular machines

[172driver]

Have to say I LOVE the reg on this one ! Probably a fitting description.

[Zulu Alpha]

gasax,

You are working it out per hour. Try working it out per mile as if flies quite a bit faster.

[Green Knight]

Kerosene Based Rotary

Well there is the other way around this, certainly for machines like the Glasair and Lancair (although they do seem to have more imaginative pricing), it needs a bit more work for me to want to put it in an aircraft, but it powers our research vehicles (mainly tracked through electric drive) just fine.

Efficiency is in the middle between the Walter and an Austro.

Walter 601 = 0.68lb/hp/hr (£0.374/hp/hr)
ADM RR1 = 0.52lb/hp/hr (£0.286/hp/hr)
Lycoming TIO540 = 0.47lb/hp/hr (0.59/hp/hr)
Austro = 0.4lb/hp/hr (£0.22/hp/hr)

JET A1 = £1/litre (~£0.55/lb)
100LL = £2/litre (~£1.26/lb)

But the inverse is true for the weight, power is also quite limited at the moment, I spoke to Textron and they hope to have something workable in a 4 cylinder form this time next year, but it wont be cheap!

In the mean time I guess we will keep plugging away at the RR1 and 192kg isnt to shabby for 300KW (400HP), although this is on a 75% full power duty cycle, so will require more work and derating. The main aero application is currently seen as APU (for those that dont want to spend $600k on the equivalent item from honeywell). There is probibly a bit more weight saving to come out the rotors and the end casings, so may find ~-18kg.


Im not sure how quick ICBM is but 400hp should give you 300+kts

[magpienja]

Goes quite well in a Landrover.

[IO540]

JET A1 = £1/litre (~£0.55/lb)
100LL = £2/litre (~£1.26/lb)

I don't think so, with the tax on avtur for private use.

Not sure how they are working the collection though.....

[flyingfemme]

Cost is the main reason why light turboprops are not more common. You can buy a turbine conversion for your 206, 210 or Bonanza - starting around half a million dollars. An uncertified engine is available for quite a bit less if you are flying experimental but this is not an option for Europe-based aircraft.
You also need a higher level of technical expertise to maintain one on a homebuilt.
Jet fuel is taxed, for private use, in Euroland so the running cost benefit no longer exists.
Pilot training is also an issue - type ratings etc for turbine power on the eastern side of the Atlantic. Probably quite awkward to define in an uncertified model.
Change, in aviation, is very expensive (because the authorities say so) so don't expect any in the near future.

[IO540]

There is little incentive to make turbines work because they burn much more fuel per HP than pistons, and the only way to recoup some of the loss is by getting a high TAS gain which means flying high, say FL200+, which is possible but difficult unless pressurised (oxygen flow is high at those levels, as I know having flown at FL200 a number of times in the TB20, and one has to breathe so deliberately that this is not a game for "kids" etc) and there are very few pressurised airframes around.

The PA46 is the one good case for a conversion - the Jetprop. That works very well, and is much cheaper to run than say a TBM. OTOH it has the build quality and strength of a Piper, not a TBM

[VMC-on-top]

Jet fuel is taxed, for private use

I thought this was only a proposal by the uk govt at the moment and hadn't reached legislation yet?

[flyingfemme]

In the UK jet fuel is taxed by consent - when you buy a tankful there is a statement on the uplift form to be signed so you certify if it is for "personal pleasure" use. If it is, you are expected to make a declaration to HMRC and send it in to them with a cheque. I think the duty rate is about 52ppl.
You will, of course, have paid VAT on it, if not for export - probably at 5%.
Across the rest of Europe there is generally no choice; VAT and duty are added to the bill automatically, unless you can provide an AOC with your tail number clearly stated. This is actually contrary to EU law, which allows any non-private pleasure user to uplift duty free fuel.
The Isle of Man does not allow AOC use on their register but many M reg aircraft are corporate and, therefore, business use. They helpfully provide an official certificate of "business" use to show to fuellers but it is mostly dismissed and the taxes charged.
Rebates of duty, as with the UK "drawback", are pretty much unavailable anywhere else.

[Piltdown Man]

Why not? Certification costs - Conversion costs - Fuel Burn (slightly more per hour for most GA folk) - New price - More training (even thought they are simpler!) - Heavy Duty Battery requirements (and maybe even GPUs).

PM