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Re: [Paparazzi-devel] My new toy is ALIVE


From: Chris
Subject: Re: [Paparazzi-devel] My new toy is ALIVE
Date: Wed, 14 Nov 2012 19:48:38 +0200
User-agent: Mozilla/5.0 (X11; Linux i686; rv:16.0) Gecko/20121028 Thunderbird/16.0.2

Hi Reto yes i will post in the wiki as soon as possible (for sure tomorrow at work). About the flutter problem, i use a Kontronik Tango 45-06 with a 13X8 Graupner and 8S lipo which gives me a pitch speed of 108km/h and that gives me a final speed below the X8's fluttering speed of ~100km/h Either use flat or round carbon spars spanwise (i use flat) where the X8's spars end for starters or better take a carbon or glass cloth and reinforce from the leading edges to about 15-20cm minimum in to the wing which is very easy to do (use a little spray adhesive on the wing, apply cloth and after 10 minutes apply resin or the lighter water based 2 component floor varnish)
In other words create a "U" reinforcement at the leading edges.
I intend to cover the wings with fiberglass cloth also.
Here is a post i found interesting:

Causes (and potential fixes) of flutter in foam planes:
1. aileron/elevon flutter (if the stock push rods and horns are used, there is gap and the gap lets the elevon to move and now only what is needed to induce the resonant frequency of the elevon and brrrr bang). Fix: use better pushrods and horns, with better tolerances, it is good if there is no play when you try to move it with your hand. 2. wing twisting (happens because it is not stiff enough) (make the wing more stiff, e.g. by covering it with glass fiber) The stiffness of the leading edge (first 50%) of the wing is most critical component in avoidance of wing twisting that may lead to flutter.
Chris





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