Turboprops?

Question

The first person to find me the maximum speed of ANY turboprop at sea level versus its maximum performance at altitude will get 10 points.

preferably a single or low horsepower twin

Thanks for the incredibly vague answer with no useful info whatsoever.

Just seeing if its as hard to find as It seems.
What Im really looking to do is find the actual performance of the turboprop by using formulas for induced and parasitic drag on all components of the aircraft to see how dramatic the differences in performance are.
The turbine produces the same power at the same RPM at all altitudes, but the efficiency of the propeller and the parasitic drag on the airframe vary greatly.
If I have the speed, altitude, and the vital statistic on the aircraft, then I can actually calculate what the actual reduction in drag and efficiency of the propeller are, and that they do not decrease at the same rate with altitude.
Any altitude would be fine because once I know the stats on the prop, engine, and airframe, then Its simple to calculate the drag and thrust and then use basic trig to find out the performance at any given altitude.

Answer 1

The TBM does not cruise at 360k, not even the 850 model. I've cruised at about 290 plus or minus about 5 knots at FL 290, in the 700. I think the max cruise in the 850 is around 320k. The Piaggio Avanti II is quite fast for a turbo prop---up around 390k plus at altitude.
In jets, the max speed at sea level is considerably less than the max speed at specified higher altitudes, so a little surprised by the numbers proffered in a couple of the responses. For example, in 3 of the jets I fly, the Vmo is dependent on altitude and is less below 8,000 than in the next higher altitude segment. As much as 30 knots less than the Vmo at the next higher specified altitudes. So, Vmo is dependent on altitude in jets I am familiar with. Also, speed will drop off at very high altitudes, such as above FL 390 or so, but lower fuel consumption will emerge as the principal reason for flying up there (and possibly weather avoidance or better winds).
Anyway, good luck with your project.
Anyway, from a pilot's point of view, weight, temperature, altitude, fuel flow, power setting, and other variables are relevant.

Answer 2

Its difficult to tell what the max speed of an airplane is at sea level, since the only time it would ever be there is when its on land.

There are turbo singles like the TBM Socata that cruises at about 360 knots at FL 200.

Speeds at altitude versus speeds at low altitude (sea level) are typically limited by different things. At higher altitudes, speed it typically limited by a critical mach number , which is an aerodynamic limitation, whereas at low altitudes it is limited by structural concerns. Each airplane is different though.

Edit: Adding information..As an aircraft climbs, its indicated airspeed will decrease relative to its true airspeed. So indicating 200 knots at 20,000 feet is actually faster than 200knots at sea level. Also, aircraft typically go a bit slower as they climb due to the scarcity of the air. However, this is offset by a larger reduction in drag that improves fuel economy.

Answer 3

This is a pretty dorky question. What altitude are you asking about? Max ceiling? Max cruise? This sort of info is available from manufactures.
In our P3 we would practice enemy fighter evasion by dropping from whatever altitude we were down to sea level (20 - 50 feet above the water) and fly at 400+ K

Answer 4

For example, the Beech 1900 (which I fly in regularly from FLL to EYW) twin engine turbo;

At Sea level 303 Kts (556 Km/hr). At Cruise altitude 288 Kts (533 Km/hr)

Answer 5

So Skytrain is a Tube-Slug (P-3 Orion Crew) ??

Answer 6

Vague answer? How about your vague question? You might as well ask how long is a rope.

Answer 7

http://en.wikipedia.org/wiki/L-410

tiwn engined turboprop, 20 passengers

Answer 8

Ok
I found it. Now what do I do with it ?