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# 3 - Gary Robinson 03/15/2012 - 23:59 - City: Clackamas - State: OR - Country: USA
Hi,
I am envolved in model airplane pylon racing and appreciate your article on gyroscopic behavior of propellers. As a retired physicist I have also looked into this problem especially with regard to propeller vibrations and flight dynamics in F3D pylon racing. It is my impression that the F3D community until now generally has not understod the pulsating character of this gyroscopic moment.

An article for example by Dr Martin Hepperle on his home page about gyroscopic moments of F3D propellers did not recognise the pulsating character and also had several other serious errors. I communicated with him on this matter about a year ago. Hoeever this article now seems to be withdrawn.

In F3D, higher engine performance with more torque variations per engine revolution, as well as increased turn rates using flaps now contribute to increased loads on the propeller blades. The blades are also made thinner, especially at the tips. According to preliminary measurements I have done there is now a risk that the resonance frequency of the propeller blades can be excited in the direction of the gyroscopic force. Coupled with increasing engine torque oscillations in the plane of propeller rotation we could have a propeller performance issue and a strength problem. Have you considered and discussed this resonance problem?

Regards,
Gert
# 2 - Gert Bjarnholt 10/28/2011 - 17:46 - City: Tyreso - State: - Country: Sweden
This is the new guestbook for Supercoolprops.com
# 1 - Beth 10/15/2011 - 09:34 - City: - State: - Country:
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