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Thread: GA Turboprop

  1. #11
    steveinindy's Avatar
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    feed (they *typically* use 50% more fuel per hp delivered than a reciprocating engine)
    Once again, it depends on what engines you're comparing. A PT-6A which is what a lot of GA pilots think of when you say "turboprop" is a pretty inefficient engine. The difference is probably closer to 15-30% more instead of 50% unless you're going for the difference between a very low end recip and a poor quality turboprop. I based this guess off of the Honeywell/Garrett TPE-331-10AV that I am planning on using for my aircraft is rated at sea level at 0.53 lbs/hp/hr (for 940 shaft hp) as opposed to the various reciprocating engines I could have fallen back upon.

    Then again, the fuel consumption kind of balances out once you factor in that you're generally going considerably faster which means you spend less time burning fuel than you would in recip powered aircraft.

    The other two benefits of turboprops is that you don't get exposed to lead and there's a reduced risk of fire associated with either fueling or being in a crash involving an aircraft using Jet-A than with a similar aircraft utilizing 100LL or mogas. There's a reason why the Navy uses kerosene based fuels on its aircraft carriers.
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  2. #12

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    Quote Originally Posted by Kyle Boatright View Post
    There are three primary advantages of turboprops. First, they are more reliable than piston engines. Second, they are smaller and lighter than piston engines. Third, they can run on a number of more common fuels, including diesel and (for some engines) gasoline.

    Their disadvantages are that they are expensive to purchase, feed (they *typically* use 50% more fuel per hp delivered than a reciprocating engine), and maintain, relative to piston engines. Also, they are loud and their exhaust smells like a BBQ grill gone wrong.
    OK, I see. Are they considered more reliable than piston engines? And if so does that translate to a safer airplane using a turboprop instead of a piston?

  3. #13

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    Kyle, if your bar b que grill smells like a diesel, then you must be grilling something bad or the neighbors cat got caught in there. Switch out that possum meat for some real brisket.

    I think a turbo smells like a diesel garbage truck, and some of them at idle sound like an engine running without oil in the bearings. There was an OV-1, ( Ithink) that parked right behind me at EAA. People would hold their ears or leave the area when it started up. It doesn't seem to effect the people inside the plane, but sure makes it unpleasant for anyone else outside on the airport, and makes hanging around the airport not the relaxing experience it is as some small airfields. I think it is not only the volume of the noise, but the high pitch. Not like hearing Bethoven at a full volume.

    And as for as not wanting to have to talk to ATC for all of every flight, darn right. Now sometimes the weather is IMC, and part of getting through it is to talk to ATC. But on a nice CAVU day, particularly if flying in less crowded airspace, I certainly don't want to spend several hours of a flight listening to ATC yammer. It would be like if you went for a walk in the woods or a pleasure drive in the country or a bike ride and you were required to listen and talk to a local cop channel or talk show radio.
    Last edited by Bill Greenwood; 04-14-2012 at 03:10 PM.

  4. #14
    steveinindy's Avatar
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    Are they considered more reliable than piston engines
    Yes. That's what he said.

    And if so does that translate to a safer airplane using a turboprop instead of a piston?
    At least from a mechanical standpoint, yes. The problem is that turboprops are high-performance aircraft and you run into human factors issues....
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  5. #15

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    Quote Originally Posted by steveinindy View Post
    Yes. That's what he said.
    I see I was a little too quick with my response but thanks anyway.

    Next question: Are there any new turboprops for less that $75k out there, or is that just wishful thinking?

  6. #16
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    Quote Originally Posted by kjensen View Post
    I see I was a little too quick with my response but thanks anyway.

    Next question: Are there any new turboprops for less that $75k out there, or is that just wishful thinking?
    Yeah, very much wishful thinking.
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  7. #17

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    Quote Originally Posted by uavmx View Post
    There's got to be enough smart people that can get together and build something that fits those parameters.
    Well, Detroit has played with gas turbine engines in cars for a long time and they have yet to hit on the right combination of practical and affordable. The stumbling block seems to be finding a recipe for mass-producing the internals. Lot of engineering talent and $$$ has been expended looking for solutions.

  8. #18

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    Quote Originally Posted by kjensen View Post
    Are there any new turboprops for less that $75k out there?
    Only if you find a 75% off sale to go with it.

  9. #19

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    Quote Originally Posted by steveinindy View Post
    Yeah, very much wishful thinking.
    That's too bad. At what price do you think a turboprop would be interesting for the majority of general aviation?

  10. #20

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    Steve has hit on the real pro's and con's of engine selection - mission of the aircraft.

    If I wanted a true "cross the country" cross country aircraft it would look pretty good as an option. Maybe not so much for taking a friend up for an hour of sight seeing or for some touch and go practice.

    Plus we have to avoid the infamous apples-to-oranges on fuel burn. Putting a turboprop engine against a O-200 isn't fair for comparing fuel consumption - one has to go to like horsepower types, where I think it might not be too different.

    Not to say that I'd want to pay the bill just to do the runup on a turboprop, mind you...or want to tolerate the hugs and kisses from the maintenance guys when I showed up with one.
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