Turboprop 10?

[JDRhodes]

Originally Posted by majuro15

I'm interested in this as a second option to the IO-540. At the rate that 540s are getting hard to find used and the higher and higher cost of new ones, this could be a doable project if reliability and compatability proves they are on par. Not to mention the fuel issue and price of 100LL (and/or replacement later on). This is what experimental aviation is all about! I'll put oxygen in my plane anyway, be happy to get up to 18K and do 200knts IAS but 300knts GS!!!

The IO-540 (one of the most widely used aviation pistons ever produced) is getting scarce and expensive, so we're going to look at a one-off brand new turbine that costs twice what a factory new Lycoming costs and burns 3X the fuel in cruise as an alternative? Huh?

[majuro15]

Wow I'm surprised as this forum is usually pretty tame about hopping on others comments. I clearly said the wrong thing and apologize for expressing interest in something different!

For what it's worth, there will be a trusty IO-540 in my airplane and I am just fine with that.

[majuro15]

I will admit my AS comments were unfounded by not keeping in mind TAS vs IAS. Big difference between the two. And I do recognize the airframe's Vne.

[glenn654]

There are a couple of big implications with all this turbine talk......

Van is going to have to come out of retirement and design a new RV for this engine.

And the engine maker is going to have to turn up the power to 11 or 12...
at least 400 shp to make it worthwhile.

I think some of you guys are getting itchy for a new project.



Glenn Wilkinson

[comfortcat]

Actually, I'd like to see the other way...

Me:
"180 shp, sipping 4gph red diesel, FADEC, 2 moving parts with a 5,000 TBO"

Wife:
"Wake up you idiot, you're dreaming again... And who's Karen?"

CC

Originally Posted by glenn654

And the engine maker is going to have to turn up the power to 11 or 12...
at least 400 shp to make it worthwhile.



Glenn Wilkinson

[Kevin Horton]

Originally Posted by Low Pass

Then there's the powerplant reliability.

Early turbine engines were very unreliable. The major manufacturers eventually learned what it took to build reliable turbine engines. A new, small manufacturer will probably have to go through their own painfull learning process before their engines have the same high reliability we expect from turbine engines from P&W, Rolls-Royce, GE, etc.

[rocketman1988]

I think that this engine design has been around for some time...it is pretty reliable.

I would LOVE to have it my -10...if it weren't for the comparatively worse fuel economy, high cost of acquisition, and lack of performance gains (re: Vne=200 KTAS), it would be my first choice of a power plant...

It would be EXTREMELY cool, though...

[Kevin Horton]

Originally Posted by rocketman1988

I think that this engine design has been around for some time...it is pretty reliable.

How many of this model have flown? How many of those have over 1000 hours of operation? I'm betting the answer is zero. If so, the real reliability is not yet known. The engine might be very reliable. Or maybe not. We just don't know. We also don't know what installation details are critical to achieve the hoped for reliability, as these details are only learned via service experience.

[rocketman1988]

Actually, if you re-read my post, I stated that the engine DESIGN has been around for awhile. Single shaft radial compressor with annular combustion chamber and axial turbine section...sounds a lot like an APU, and there are THOUSANDS of these operating for MILLIONS of hours. Or you might look at the Merlin/Metroliner...myself, I have 5000 hours in the Metro and never had a single hiccup from an engine.

No, I think it is pretty much a proven design. Now whether or not they can make it work in the -10, that remains to be seen. I would give you odds that it will work just fine. Then you look at the Lycoming and all of it's related issues, probably the greatest of which is keeping the darn thing cool, and well, the turboprop starts to look more and more attractive...

Again, if the acquisition cost was reasonable and the fuel flows were comparable, I, personally, would take the turboprop over the Lycoming in a heartbeat.

Unfortunately, that is probably not going to happen any time soon, so it will be a Lycosaurus for my -10

[Kevin Horton]

Originally Posted by rocketman1988

Actually, if you re-read my post, I stated that the engine DESIGN has been around for awhile. Single shaft radial compressor with annular combustion chamber and axial turbine section...sounds a lot like an APU, and there are THOUSANDS of these operating for MILLIONS of hours. Or you might look at the Merlin/Metroliner...myself, I have 5000 hours in the Metro and never had a single hiccup from an engine.

No, I think it is pretty much a proven design. Now whether or not they can make it work in the -10, that remains to be seen. I would give you odds that it will work just fine. Then you look at the Lycoming and all of it's related issues, probably the greatest of which is keeping the darn thing cool, and well, the turboprop starts to look more and more attractive...

That's a bit like saying that a VW Beetle engine would make a great aircraft engine because it is a four cylinder, air-cooled, horizontally opposed engine, and the good service history of Lycoming and Continental prove that this is a good design. In fact, the early VW users in aircraft experienced many failures, until they learned what modifications were required to achieve acceptable reliability. The Lycoming ALF-502 turbo-fan engine had a pretty terrible service history in the early years, until Lycoming made enough detail design changes to make it a reliable engine.

There is a lot more to reliability than the choice of basic design layout. Details matter. The only way to learn whether they have the details right is lots of test time, either by the manufacturer (if they have the budget for many thousand hours of test time in actual aircraft), or by the early users (i.e. those who choose to be beta testers)

I've had two engine failures over the years, and both were on turbine engines - one was an ALF-502 on a Canadair Challenger, and one was a J-85 on a Canadair Tutor. So much for the vaunted turbine engine reliability.