Prop speeds
Thread Starter
Joined: Oct 2006
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From: cornwall UK
Prop speeds
Can someone tell me roughly the operating range for prop speeds on a turbo prop aircraft? My Google search gives me every detail known to man except prop speeds.
Much obliged
Much obliged
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From: london, UK
well thats probably still true. Tip speeds get close to and sometimes through the speed of sound - boeing stearmans make the rasping noise they do because of the tips going supersonic. A 90" prop on something like a king air is describing a path about 7 metres round and at 2200 rpm thats ..um M0.78.
Saturday afternoon maths of course..
Do you mean just rpm? if so, no idea, google is your friend
http://www.enhanced.aero/pdf/performance_raisbeck.pdf
(might be talking rubbish.. am sitting here watching the F1)
Saturday afternoon maths of course..
Do you mean just rpm? if so, no idea, google is your friend
http://www.enhanced.aero/pdf/performance_raisbeck.pdf
(might be talking rubbish.. am sitting here watching the F1)
Last edited by tommoutrie; 3rd November 2012 at 15:56.
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From: Brisbane, Australia
Just to add another, larger diameter turbo-prop to the mix.
The Lockheed P3 Orion, and therefore the Electra props are constant speed (in flight) at 1,021 rpm, with an 11 foot diameter prop if I recall!
Though the Electra had square-tipped and the Orion round-tipped prop blades.
The Lockheed P3 Orion, and therefore the Electra props are constant speed (in flight) at 1,021 rpm, with an 11 foot diameter prop if I recall!
Though the Electra had square-tipped and the Orion round-tipped prop blades.
Last edited by EW73; 3rd November 2012 at 23:53.
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From: Canada
Homebuilts powered by Volkswagen engines typically have a 3300 RPM redline.
However if you wanted to generalize:
Large Turboprop airliners (30 plus seats): prop RPM range 800-1200
Small Turboprops.................................................. .....1700-2200
Pistons engines ........................................................1800-2700
However if you wanted to generalize:
Large Turboprop airliners (30 plus seats): prop RPM range 800-1200
Small Turboprops.................................................. .....1700-2200
Pistons engines ........................................................1800-2700
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From: flyover country USA
The BIIIG pistons had even slower-turning props.
For example - P&W R-4360-4
Max crankshaft RPM = 2700
Reduction gear ratio = 0.425
Resulting prop RPM = 1148
Other R-4360s had gear ratios as low as 0.333, for prop rpm = 900.
For example - P&W R-4360-4
Max crankshaft RPM = 2700
Reduction gear ratio = 0.425
Resulting prop RPM = 1148
Other R-4360s had gear ratios as low as 0.333, for prop rpm = 900.
Last edited by barit1; 4th November 2012 at 01:25.
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From: Austria
DH8D:
maximum (takeoff/go around) 1020, as has been mentioned; climb power 900, cruise power 850 (also useable for climb and landing; brings some reduction in noise and performance).
DH8C: Maximum 1200, intermediate setting 1050, cruise 900 rpm. Also on this series, 900rpm is allowed for climb and landing with some performance penalty but noticeably less cabin noise.
NK-12 powered turboprops (Tupolev 95, An-22): 700rpm, which results in supersonic tip speeds due to the large propellers. Still seems to be efficient though.
maximum (takeoff/go around) 1020, as has been mentioned; climb power 900, cruise power 850 (also useable for climb and landing; brings some reduction in noise and performance).
DH8C: Maximum 1200, intermediate setting 1050, cruise 900 rpm. Also on this series, 900rpm is allowed for climb and landing with some performance penalty but noticeably less cabin noise.
NK-12 powered turboprops (Tupolev 95, An-22): 700rpm, which results in supersonic tip speeds due to the large propellers. Still seems to be efficient though.
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From: Correr es mi destino por no llevar papel
IIRC (five years have passed) ATR 42-300 with PW120 and Hamilton 14SF5 four bladed props used 100% for takeoff and approach, 86% detent for climb and 77% for cruise when out of icing conditions, 100% being 1200 RPM. We could set RPM anywhere between detents and often used 92% for cruise in icing conditions as it was less noisy than 86%, increase in consumption was minuscule and cruise speed (250 KTAS) not affected.
Thread Starter
Joined: Oct 2006
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From: cornwall UK
Prop speeds
Many thanks for the further info. As an ex-rotary man I had thought that cruise rpm would have been about 2000 as with piston engines, say DC3. An eye-opener to see rpm as low as 850.
Boslandew
Boslandew
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From: Texas
Looked through a couple old manuals, both the P&W 1830-94 and Wright 1820-80 have 16/9 reduction gears. So if the engine is turning 2050 rpm in cruise, the prop is turning about 1150 rpm. I know R985s don't have a reduction gear and judging from the sound R1340s don't either.
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From: flyover country USA
R-1340 prop speeds
There are both direct-drive and geared (3/2) versions; the direct-drive model is much more common. The geared version (R-1340-AN-2) was built primarily for large blimps, with oversize prop for low-speed efficiency.
Thread Starter
Joined: Oct 2006
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From: cornwall UK
Prop speeds
The logical question has just occurred to me. Why should turboprop rpm be half that of a piston engine on a comparable type, say DC3 against DH8C.
Probably not a good comparison of types but I hope you get the point I'm trying to make
Probably not a good comparison of types but I hope you get the point I'm trying to make
Last edited by Boslandew; 5th November 2012 at 09:04.
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From: Germany
Why should turboprop rpm be half that of a piston engine on a comparable type, say DC3 against DH8C.
i think the extreme was a lockheed starliner where the engine turned the props via a .355 gearing so prop speeds were something about 750-800rpm in cruise .
Thread Starter
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From: cornwall UK
Aerobat
Probably didn't use precise enough terms. According the Pilots Notes Once had, the DC3 Prop turns at about 2000 RPM plus or minus a bit in the cruise, nearly twice that quoted below for, say, the Q400. Have I missed something?
Probably didn't use precise enough terms. According the Pilots Notes Once had, the DC3 Prop turns at about 2000 RPM plus or minus a bit in the cruise, nearly twice that quoted below for, say, the Q400. Have I missed something?
