TWAMD-80 From United States of America, joined Oct 2001, 1006 posts, RR: 3
Reply 1, posted (14 years 3 months 2 weeks 2 days 21 hours ago) and read 2815 times:
An advantage of a turboprop over a piston is that it can cruise at a faster speed. A disadvantage of turboprops is that the operating cost is higher than a piston's operating cost. However, I'm not exactly sure about the economics.
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Goldenshield From United States of America, joined Jan 2001, 6170 posts, RR: 13
Reply 2, posted (14 years 3 months 2 weeks 2 days 21 hours ago) and read 2811 times:
The turboprop is the least expensive turbine to operate, due to the fact that there is a prop, pushing lots of air, at a relatively slow speed. It is usually most efficient in the .3-.5 mach range.
The piston often cant go as high as a turboprop, since it relies on normal aspiration to feed the engine. A turboprop uses a turbine, which is relatively the same pressure in the air, as on the ground.
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Jeff G From United States of America, joined Jan 2002, 449 posts, RR: 1
Reply 3, posted (14 years 3 months 2 weeks 2 days 21 hours ago) and read 2806 times:
Pistons in general are much cheaper to operate than similar size turboprops. Turboprop engines are far more expensive than their piston counterparts to purchase and maintain, and burn more fuel. But turboprops are more reliable and easier to use. It's relatively easy to wreck a high-end, especially turbocharged, piston engine with sloppy handling. Turboprops are almost bulletproof. Just keep temperatures out of the red, and you're good to go.
BTW, Goldenshield, you have it exactly backward: turbocharged piston engines are the engines that see higher pressures to the engine than at sea level. All turboprops are normally aspirated and lose power as they climb. You can get around that limitation by flat-rating the engine, in essence behaving like a turbocharged engine, but they are still normally aspirated.
XFSUgimpLB41X From United States of America, joined Aug 2000, 4300 posts, RR: 34
Reply 6, posted (14 years 3 months 2 weeks 1 day 16 hours ago) and read 2750 times:
Some pistons like the Cessna 421 are pressurized...it's pressurization comes off of the turbocharger.
I've never heard of a piston that is as fast as its turbine counterpart....and Jeff G is right.. you lose power as you gain altitude. You can see the torque fall off as you climb up and have to up the power levers just like you do in a piston...just the fact that you are putting out an unholy amount of torque at any altitude though makes up for that fact.