ANALYSIS OF THE PRE-ROTATION ENGINE LOADS IN THE AUTOGYRO

Jean Claude

Jean Claude

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Location
Centre FRANCE
Aircraft
I piloted gliders C800, Bijave, C 310, airplanes Piper J3 , PA 28, Jodel D117, DR 220, Cessna 150, C
Total Flight Time
About 500 h (FW + ultra light)

Authors
Zbigniew Czyż1, Tomasz Łusiak2, Daniel Czyz1, Dariusz Kasperek3

Comment
This paper shows the calculation of the power required to pre-rotate an autogyro rotor applied to an 8.8 x 0.22 m two-blade of 9H12 NACA section.
Unfortunately, it omits the effect of the induced speed due to static lift, since the pitch setting is not zero.
The drag coefficient of the blade sections is based on an angle of attack of the sections of 2°, but do not confuse this angle with the pitch setting
and it is not specified how they obtained this 2° value.
It therefore seems to me that the predicted power (5.5 kW at 250 rpm) is significantly underestimated (by 30%?).
 
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Jean Claude said:

Authors
Zbigniew Czyż1, Tomasz Łusiak2, Daniel Czyz1, Dariusz Kasperek3

Comment
This paper shows the calculation of the power required to pre-rotate an autogyro rotor applied to an 8.8 x 0.22 m two-blade of 9H12 NACA section.
Unfortunately, it omits the effect of the induced speed due to static lift, since the pitch setting is not zero.
The drag coefficient of the blade sections is based on an angle of attack of the sections of 2°, but do not confuse this angle with the pitch setting
and it is not specified how they obtained this 2° value.
It therefore seems to me that the predicted power (5.5 kW at 250 rpm) is significantly underestimated (by 30%?).
Click to expand...

Inserting the numbers in the formula you gave in a post dated Oct 23, (pls see below) the power required to keep that rotor at 250 rpm seems to be quite high... I get 9,5 kW...

[RotaryForum.com] - ANALYSIS OF THE PRE-ROTATION ENGINE LOADS IN THE AUTOGYRO
 
Yes Xavier (but rather 8.9 kW with my calculator)
The aerodynamic characteristics on which this authors rely are those obtained in wind tunnels, systematically reduced to the infinite aspect ratio when no indication to the contrary is given
So, they omit losses due to the finite aspect ratio of the blades and to the induced speed through the rotor disk
 
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