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Flying the Lancair Evolution turboprop in Europe (production moved to Europe)

This thread might be more relevant for comparing against certified TPs.

There is also a long Cirrus Jet thread which contains some preliminary perf data. I would be totally amazed if this turbojet got anywhere near a turboprop on the basic numbers. Jets start with a huge handicap (except the huge marketing advantage of sex appeal ) which they regain only by flying high up in thin air.

There is a Flaris thread here

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

You have lost me completely. You are arguing something which nobody is arguing about, for or against. I can’t see the relevance of whether a TBM850 is for “governmental work” which is complete bollocks since most of them are private owner flown.

What I mean is that the Evolution is simply a TBM or Meridian that is shrunk to Cirrus size. It does not offer anything that the TBM doesn’t. A good example of a homebuilt that does not exist in certified form, it is not – except for the shrinking, making it a more “personal” looking and performing aircraft than the “governmental looking” TBM Even the price of this homebuilt is comparable to a similar, but much larger certified aircraft.

Jan_Olieslagers wrote:

Neither can I understand the use of adding the pictures, I think most of us know what those planes look like.

The other pictures was the Cozy and the Velocity. They are both tourers, 200 kts. A top of the line Velocity with 250 kt cruising speed cost 300k, and this includes a brand new TSIO 550 and full IFR panel, leather interior etc. Then the turboprop RV10 and the jet Subsonex. They use the PBS jet/turboprop engine, full FADEC, more than 500 sold since they started selling it in 2008. The TP RV-10 has only 240 hp, so it doesn’t perform much better than the 260 HP 540, but it cruises along at 150 kts at 10k feet using 14 GPH of jet A1. The same guys are also building a TP Velocity conversion using the PBS. A PBS TP100 doesn’t “cost more” than a TSIO 550, probably less, and what you get is 240 HP of turbine power governed by FADEC using Jet fuel instead of AVGAS.

The elephant is the circulation
ENVA ENOP ENMO, Norway

Even the price of this homebuilt is comparable to a similar, but much larger certified aircraft

Obviously, that’s because there is no free lunch in technology.

You want a cheap plane, you will get a cheaply built plane.

You want cheap maintenance, you have to do it yourself (or get somebody else to do it for free, but then where is their payback?).

It doesn’t matter (much) whether it is certified or homebuilt.

240 HP of turbine power

240HP is not much. Bear in mind also that a TP is normally aspirated so loses power as you climb.

Also small jet engines are even more horribly inefficient than the bigger ones.

240HP would be OK for a very small plane – a little 2-seater.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

Obviously, that’s because there is no free lunch in technology.

There is nothing advanced in the Evolution that is not there in a TBM or Meridian, or that Mustang for that matter (twin jet). The only thing with the Evolution is it’s smaller and lighter. Maybe it’s just me, but I simply don’t get the logic behind the Evolution. It has none of the benefits of a homebuilt, and it has none of the benefits of a certified aircraft. It’s a good performer and it’s cool, that’s it, but it’s insanely expensive, comparable to a light certified twin jet, and most of what you pay for are potential problems waiting to happen, things you cannot fix yourself. It is always beneficial for a homebuilder to use certified parts and systems if available and they are comparable in price/performance, due to maintainability and resale value (if a dependable and long lasting aircraft is what you are after, that is, which is not always the case with an experimental homebuilt).

Peter wrote:

You want a cheap plane, you will get a cheaply built plane.

Not if you build it yourself (and I’m not telling if I mean a cheap plane or cheaply built plane ) The Evolution fails in this department, that’s the point. It’s a homebuilt at premium certified cost, no matter how you look at it.

Peter wrote:

240HP is not much. Bear in mind also that a TP is normally aspirated so loses power as you climb at the same rate as a piston engine.

The TP100 has FADEC. It is flat rated to 180 kW. Even without FADEC a TP looses much less power with altitude in general than a piston engine. At 20k feet a normally aspirated piston only has 40% power left, while a TP has 60% (in general, but could be a bit more or less depending on design and rating).

Peter wrote:

240HP would be OK for a very small plane – a little 2-seater.

That depends entirely of what you want. The TP100 is a direct replacement for the O540. It is the turboprop engine homebuilders (some of them at least) have been waiting for since the beginning of times. Already the RV-10 is fitted with one, soon the Velocity, the Subsonex has the jet version, and I think also a couple of BDs, and I’m sure lots of others will follow. We may even see microlights with this engine. Not that it necessarily makes sense, in a getting from A to B kind of way, but making that kind of sense is not necessarily a priority. That is what I don’t like about the Evolution. It is marketed, and sold, as a competitor to top of the line certified aircraft that make sense (if you got the money), at a comparable price, while in reality it is the kind of homebuilt aircraft that does not make awfully much sense, and it is not even a real homebuilt.

The elephant is the circulation
ENVA ENOP ENMO, Norway
a TP is normally aspirated

Another illustration of the danger of abbreviations. The full “turboprop” would have shown that a TP always has a turbo. By definition.

EBZH Kiewit, Belgium

A turboprop and a turbojet engine are both normally aspirated. There is no “turbo” in the piston engine context i.e. there is no device which maintains the inlet air pressure at some regulated (or even boosted) level.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

A turboprop and a turbojet engine are both normally aspirated. There is no “turbo” in the piston engine context i.e. there is no device which maintains the inlet air pressure at some regulated (or even boosted) level.

In some sense there is. The power is limited by temperature, pressure and rpm of the core compressor/turbine. At the same time the power is also limited by the torque and/or thrust of the propeller/power turbine and gearbox assembly. By making the core able to deliver more power (hot exhaust gases for the power turbine) at sea level than the max thrust/torque of the power turbine/propeller, the engine will be able to deliver max thrust/torque at much higher altitudes. This is essentially the same as a turbo does, the effect is the same.

The elephant is the circulation
ENVA ENOP ENMO, Norway

That, however, AIUI, is not due to external maintenance of the inlet air pressure. It is due to the engine being de-rated low down. It would be a bit like a 250HP IO540 being derated (and say FADEC controlled) to 100HP, and then you could say the output is constant from MSL to FL180. The turbine limitations (torque, temps, etc, whatever) achieve the same effect.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

That, however, AIUI, is not due to external maintenance of the inlet air pressure.

That is precisely what it is. Thermodynamic vise there is no difference between a turbo and the core turbine of a TP. The job the core turbine has to do is to deliver energy (hot exhaust gases) for the power turbine, and that’s it. It does this by increasing or decreasing RPM according to the fuel rate. The inlet pressure is in this case the outlet pressure (pressure, density and temperature) of the core turbine. All the excess energy or power is extracted through the power turbine. A turbo is a device that does the same thing for the piston engine, but the inlet pressure and temperature is of course very different.

The similarity would be if the power turbine and the compressor turbine were mounted on the same shaft. This will be like a normally aspirated piston engine, because you loose one degree of freedom – the pressure, density and temperature control of the gases into the power turbine. Several engines are built like this also, particularly early turbo jets. The engine I know (or should know from way back ) is the PW F-100 for the F-16. It is a double spool low bypass turbo jet, with augmented afterburner. The power at all altitudes and the augmented (uses fresh air) afterburner would be completely impossible without the free spinning inner core turbine/combustion/compressor unit, which essentially is the “turbo” for a jet engine.

A flat rated turboprop is very much like a piston engine with a normalized turbo. A car engine with a turbo is a bit different, this would be like a a TP where the power turbine and gear and propeller where increased to output the max available zero alt power from the core turbine. Such a TP would loose power quickly with altitude.

I know what you mean, but it’s not correct. A more correct view (IMO, even though it is only for explanation, not necessarily how it is done) is the max power is designed according to the max propeller torque, and also the available power from the power turbine at a given inlet pressure and temperature. Then the inner turbine is designed to supply the power turbine with that pressure and temperature at the altitude the aircraft needs it. If that alt is 25k feet, then obviously the core turbine would be able to produce much more pressure at lower alt, but not without exceeding the structural limits of the prop, shaft, gears etc. Therefore the inner core has to reduce (maintain) the same pressure further down, hence it must be flat rated.

The elephant is the circulation
ENVA ENOP ENMO, Norway

Here it is again – at Mali Losinj LDLO where it flies all the time

Administrator
Shoreham EGKA, United Kingdom
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