When flying at higher altitudes, does it matter if you have a turboprop vs a piston engine driving a propeller?

In general, a turbine engine will produce more power than a piston engine at higher altitudes. A turbocharged piston engine, with compressed air intake, will lose less power at altitude than an normally aspirated piston engine. A turbine engine will lose even less.

As a rough example, a normally aspirated Cirrus SR-22 has a service ceiling of 17,500 ft. A turbocharged SR-22 has a ceiling of 25,000.

A turbocharged piston Piper Malibu Mirage has a service ceiling of 25,000 ft., while the turbine powered Malibu Meridian has a ceiling of 30,000 ft.

The turboprop Pilatus PC12 and Socata TBM-850 have service ceilings of 30,000 ft. or above.

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    Might be worth comparing a pressurized piston single like a Cessna P210 or Piper Malibu - they're more directly comparable to the pressurized turbine singles you mention! Both have a service ceiling of 25,000 ft, but as with the turbo Cirrus I think that's a certification thing rather than performance. – egid Dec 21 '13 at 20:01
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    Good point. I added Malibu Mirage and Meridian. – xpda Dec 22 '13 at 2:19
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    For most of these aircraft, the altitudes you are actually maximum operating altitudes for certification purposes, not (necessarily) the same as the service ceiling (100fpm climb rate). However, what you said generally is pretty much correct. – Qantas 94 Heavy Feb 16 '14 at 13:01
  • Good point. Now that you mention it, I seem to remember the max operating altitudes on the Pilatus and Socata are set because of pressurization limits. – xpda Feb 17 '14 at 3:52
  • I don't thing this statement is correct: "A turbocharged piston engine, with compressed air intake, will lose less power at altitude than an normally aspirated piston engine. A turbine engine will lose even less." Depending upon the turbocharging system the piston system may still be producing the same power at ground level and at high altitude. A turbine will lose power as the plane climbs, but has a lot more power to start with. – JerryKur Sep 2 '14 at 16:49

Of course it does!

One simple way of looking at this is that piston-powered (well cylinders) are constant-volume engines (ie. 1200cc). As you go higher the air becomes less dense so there is less air mass (and fuel) getting into the engines. If the density becomes half what it was at sea level, you now have in effect a 600cc equivalent engine, etc. Power will be less and less.

A turboprop is a constant pressure engine, so as you climb, you kinda need to go faster and faster, but basically you still burn the same amount of air/fuel. You will lose power as you climb in a turboprop, but that's mostly cause the propeller loses efficiency at the higher speeds you fly higher up. The turbine itself is still as efficient as on the ground.

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    The turbine has it's limits too. A jet engine will at FL350 produce less than half of what it can do at sea level. But the power does indeed decline much more slowly. – Jan Hudec Feb 17 '14 at 7:37
  • +1 for constant volume vs constant pressure. The efficiency mystery makes sense now (: – kevin Dec 17 '14 at 13:30

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