Don Fry Posted August 5, 2015 Share Posted August 5, 2015 Took my Flair DR VII for its second outing today. Towards the end of the second flight I heard a peculiar whining sound, and put in for a landing. Horror, the cowl, and it has 10 ounces of weight in it, so if that had parted company, no more DR VII I suspect. My fault, bigger screws needed for such an heavy item. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted August 5, 2015 Author Share Posted August 5, 2015 Note the crack in the top of the cowl. Still shaking. Quote Link to comment Share on other sites More sharing options...
John Privett Posted August 5, 2015 Share Posted August 5, 2015 I hope you bought a lottery ticket on the way home... Quote Link to comment Share on other sites More sharing options...
Don Fry Posted August 5, 2015 Author Share Posted August 5, 2015 Wot gets me is that this flight was the first where I threw it about. The throws are as plan, and fair do'es are spot on, rolls, loops, inside and out, spins, stall turns, it don't care. The only objection was an inverted spin entry resulted in a blur where it got right way up. And I really threw it about for nine minutes. Quote Link to comment Share on other sites More sharing options...
Josip Vrandecic -Mes Posted August 5, 2015 Share Posted August 5, 2015 Hi Donald , In war, love and RC modeling.... happiness is MANDATORY... I wish you more and more successful landing... Jo Quote Link to comment Share on other sites More sharing options...
Geoff S Posted August 5, 2015 Share Posted August 5, 2015 If the cowl is ABS as I think it may be then it's not really strong enough to support that amount lead on its own. Much better to attach the lead to something much more substantial inside the engine compartment with both glue and screws. After all if you need that much lead there's no need to scrimp on the size and weight of the wood at the front. You were very lucky. Had the screws simply disappeared or did you remove them later? Geoff Quote Link to comment Share on other sites More sharing options...
Don Fry Posted August 5, 2015 Author Share Posted August 5, 2015 The cowl is an amalgam of ABS, lite ply, epoxy, and steel shot. It is a lumpy and strong piece of kit, with screws too small. Why put weight any further back than you need, law of levers applies. Quote Link to comment Share on other sites More sharing options...
Former Member Posted August 5, 2015 Share Posted August 5, 2015 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
John Privett Posted August 5, 2015 Share Posted August 5, 2015 Without the 10 ozs of lead the cowling would probably have been fine with the screws you used. How about attaching the weight to the ply that the cowl is was screwed to? It can't be significantly further back, can it? Quote Link to comment Share on other sites More sharing options...
Don Fry Posted August 6, 2015 Author Share Posted August 6, 2015 As I recall it's about 2 ounces different in weight. I know it not a lot but I have a thing about weight. I still kick myself that I built it with the kit supplied wood at the back, which is the reason for the weight at the front being there at all. Jason Channing has the answer. And possibly a set of dowel locators to take the lateral loads off the screws. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted August 6, 2015 Author Share Posted August 6, 2015 Problem cause solved, on taking cowl off plane, two screws missing, two in cowl but unattached to plane. No damage to any of the cowl fixing holes, or in the front plate of the plane( holes or threads). Conclusion is they MAY have shaken loose, or I didn't tighten them. Stupid lucky aero modeller, either way. Quote Link to comment Share on other sites More sharing options...
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