Yeah, but at altitude that's probably 60% less in lapse rate, so not so bad. And in Europe where Jet A1 isn't taxed, this could quite quickly become cheaper to run than an Lycosaurus.
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Jet A1 is only tax free if it is used to fly commercial on international routes, at least in some countries in europe. Still cheap compared to avgas, but that is mainly because avgas is a rare and therefore expensive to produce fuel.
How long would that be true if these (or any similar) engines began to be prolific?
Sadly as mentioned above it isn't really true. Whilst in the UK the self declaration thing may not be strictly observed by some, in Europe the policy seems to be more charge first ask later. Add mineral oil tax etc and you're in to serious expense. Still not as bad as 100ll though! In saying that as Peter says 18 per hour for 240hp seems fine. But if that's in the cruise as the guy said it will be 30gph or so at msl. Could be an excellent unit for the right aircraft.
I guess it makes a lot of sense for longer missions where you plan to fly FL150 for long periods of time with the comfort of a turbine engine. Not ideal for a bimble just outside the circuit
With a turbine you do get a more efficient cowling shape, generally. But the fuel is heavier so you get less range even for the same SFC, and no turbine will match the SFC of a correctly leaned piston engine.
It's lighter but that merely severely screws up your W&B, requiring a very long mounting frame - see the Jetprop conversion. The resulting position of the nose gear could impact (pun intended) the prop clearance on grass
I'd like to see the real fuel flow at say 240HP, ISA. If they are doing 18USG/hr then they have a sterling proposition but I think they will have bent some rules of physics doing that because AFAIK nobody has got anywhere near that before.
Much more reliable. But the cost of the overhaul may not be for the faint hearted! And there's the hot section check to factor in also, again probably more costly than a new Lyco or Connie. Maybe as its specifically aimed at light aircraft the costs will be more in line with reality. I hope so.
There's a rule of thumb saying that turbines start to make sense at 400BHP. I was told this is mostly a function of blade diameter as the main energy loss is due to the gap between the blade and the sheath and the larger the diameter, the smaller it is in relation to the whole thing.
One argument against turbines in single engine planes is that they stink and being placed in front of the cockpit, you get to breathe a lot of turbine exhaust. That alone would probably keep me from buying a single engine turbine.
You should not be breathing anything at all. I have an electronic CO detector and it reads zero during normal ops. Sometimes, in slow flight, you get 10-30ppm and it goes off, and sometimes it picks up the exhaust from the plane that landed before me. But during flight, the reading is zero.
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turbines start to make sense at 400BHP.
That's perhaps true for the 1960s Allison heli engines whose business Rolls Royce bought, and are trying to flog a 450HP one with a prop shaft on the end. There are some interesting developments now - example. I have no financial interest in that venture but know the people behind it well.
But no turbine will match a piston engine for SFC. Even the huge and state of the art engines on a 787 only just about match a piston engine for efficiency.
You should not be breathing anything at all. I have an electronic CO detector and it reads zero during normal ops.
CO doesn't stink Every time I was on a single engine turbine aircraft, I noticed strong exhaust smell in the cabin, especially during ground operations. Turbine exhaust is oily and has a much stronger smell than petrol engine exhaust. In a multi engine turbine, you are not seated directly behind the turbines so it's less of an issue.
I've been in a Jetprop and flown a TBM850 for 1.5hrs but never smelt anything.
I know CO doesn't smell but if exhaust was entering the cockpit then CO would register on a decent meter - unless you are running peak-EGT or LOP in which case there shouldn't be any, but you won't be doing that during high AoA flight.
There's nothing inherently difficult in the design and manufacture of turbines with todays CNC machinery. It's got fewer parts than a piston. Therefore, it is possible to design a turbine that would cost less than any piston engine. All it takes is one visionary and it could be reality tomorrow. Don't expect it from the old guard, tho - they're to comfy with their overpriced military contracts to do an about face. It will have to be an outsider.
