Vladimir,
I cannot give a detailed aerodynamic explanation. I am not talented enough to fly F1D and despite the excellent plans which are posted from time to time one does not pick up, or understand, the finer points of trimming unless one is competing oneself.
You mention models getting shorter, larger tailplanes and a more forward CG and also a reduction in wing and tailplane offset. From other sources I have heard of smaller propellers, thinner motors and a faster rate of climb. Allied to the faster climb some stalling problems have been mentioned
I am puzzled by the models getting shorter. I would have expected a thinner motor would have suited a longer motor stick and to shorten a tailboom and increase the tailplane size would seem to be staying in the same place from considerations of stiffness, weight and Vbar.
If the models are stalling on the climb then the forward movement of the CG may be a quick fix. I wonder if the stalling could be because of the thinner motors giving less torque turn to the left. Some left sidethrust would be another answer to that. The reduction in wing and tailplane offset may be another way of encouraging a left turn.
As the propeller is smaller and rotating at a different speed there will be a change in the pitching force on the propeller but I would not presume to guess whether it was of any significant magnitude.
One other factor; as most of us are engineers we like to think that ‘form follows function’ but I sometimes think that models follow fashion just like women change their skirt lengths. Anyway Vladimir I should be interested to hear your own take on the points you have mentioned.
John Barker - England
From: Indoor_Construction_at_yahoogroups.com [mailto:Indoor_Construction_at_yahoogroups.com]
Sent: 03 April 2016 00:42
To: Indoor_Construction_at_yahoogroups.com
Subject: [Indoor_Construction] F1D design changes
Dear all
It is evident in the new 1.4 g models the models
Are getting shorter with stabs getting larger. CG is moving forward. The stab offset is reducing and is the wing offset. Can anyone offer a well thought out detailed areodynamic explanation of these changes.
Vladimir Linardic
Received on Mon Apr 04 2016 - 11:06:58 CEST
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