blade angle on a seneca

[aslan1982]

if you were to pitch up in a seneca what would happen to the blade angle

what I know is the

blade angle = angle of attack plus helix

the seneca has a constant speed unit that keeps the angle of attack to its optimum by changing the blade angle.

On take off the blade angle is set to fine pitch = low blade angle
and during cruise the blade angle is set to coarse = high blade angle

as forward speed increase like on take off the blade angle starts to move towards coarse

so if i pitched up speed would decrease so the blade angle would move towards fine which would reduce the blade angle???

Please let me know if my understanding of this is correct.

Thanks in advance

[ab33t]

Whatever RPM you have set this will be maintained be reducing and increasing the pitch , so if you wanted to climb , prop(rpm) , power and that will give your pitch

[172_driver]

so if i pitched up speed would decrease so the blade angle would move to fine which would reduce the blade angle???

I concur with your reasoning, except I like to say fine(r) and coarse(r)

[fdr]

except...

the preceding is valid so long at the blade angle has not reached the fine pitch stop. If your power setting was low to start with, thew blade angle would be fine, and when it reached the fine pitch stop, any reduction in airspeed will result in a reduction in RPM.

When operating at a high angle of attack, the inflow to the propellor is not axial, but is oblique to the axis of rotation. At such times, the descending blade, RH on the PA-34 from aft for the left engine, opposite for the RH engine, has a higher angle of attack and also a higher inflow velocity than the LH blade. This causes an asymmetry of lift, being offset from the center of rotation, which increases some vibration, and results in the P factor issue on non CR aircraft.

The governor is balancing the total drag force of the blades which is dependent on the sum of each blades drag, which are different when any inflow is not axially aligned with the propellor, with the torque being output to the propellor hub by the engine. Within the governing range of blade pitch. Outside this range, RPM will vary.

regards