Jim.Thompson's blog View Details
Archive for November, 2012
Posted by Jim.Thompson | Nov 16, 2012 @ 01:58 AM | 10,684 Views
I don't think I ever posted a picture of my finished Kingcobra (P63) here on my blog. It's been flown at the last Borah Festival since this picture.

Posted by Jim.Thompson | Nov 12, 2012 @ 09:39 PM | 9,306 Views
I've have some more insights into why my servos stalled in the plank "Circa" and totalled it.
The reflexed wing section (airfoil) on a plank flies straight and level when trimmed correctly. The reflex trailing edge part of the section provided negative lift to counteract the normal forward pitching moment of the aifoil as it generates lift.
So it follows that the control surfaces (and the servos) will have a load on them in normal, level flight, to provide this self stabilising force.
Which means that as the speed increases, the demand on the servos to maintain the level flight, reflexed inclination, will increase. As in a dive!
Then, if additional demand load is required of the servo to pull the control surfaces up, it might be pushed beyond it's limit. This will happen earlier in the case of a reflexed plank airfoil, than in a tailed aircraft with a conventional airfoil. (all other factors taken into consideration.).

All the more reason for the servos to stall!

Comments, corrections and additions invited, as usual.