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Wild ride!!!

Old 03-21-2009, 10:49 PM
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CBM Racing
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Default Wild ride!!!

Have been working on my old aspire 2m sailplane. Last time it flew(4 years ago)it ended badly with a light pole collision, oops. Recently put a multiplex 480 6d motor in it, rebuilt most of the wing except the outer polyhedral panels, making it a 48 inch version. Rebuilt the nose with balsa and foam making it a little longer than stock. Looking at it, I thought, "that is plenty of dihedral for rudder/elevator set up". I was a bit mistaken. Finally took it to field today for maiden. Wasn't expecting much with the direct drive motor and 6x4 prop on 3s2100 lipo. Again, I was mistaken! Throttled up to full, ran into the ever so slight breeze, strong heave...WHOOOSHHHH!!! CRIPES! You woulda thought there was a rocket cluster strapped on it! Shot out at about 45degrees, just screaming, put into a climb to slow down and gain altitude. Shut down throttle after about a 3 second run, and was ready for the expected fast glide back down. Uh oh! As soon as throttle was down, it banked hard to the left, no amount of right stick would keep it straight, just lessened the bank angle. Had to make like 5 trips around field in constant turn before I could set it down safely. Man, what a rush! So, ordered some wing panels from tower today from there vista I believe? Going to make a 9 or so foot span, with POLYHEDRAL! . If it is still whacked out, will put on some ailerons to tame it down some. But I think it should be fine with poly wings, a 9ish foot span, all up weight of around 37ozs. Hope it goes better next time
Old 03-21-2009, 11:02 PM
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TIA
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Default RE: Wild ride!!!

With the larger wing you should be able to get that thing to thermal without even thinking about it!

Welcome to the world of LMR.
Old 03-22-2009, 01:21 PM
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Default RE: Wild ride!!!

With the tail only being 16 1/4 inches behind trailing edge of wing, will it cause problems going from a 2meter ship to 9+ foot span? Almost concerned about it, but guess time will tell, unless someone knows if it is an issue?
Old 03-22-2009, 01:48 PM
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Default RE: Wild ride!!!

Well it might be pitch sensitive and more difficult to turn. May try to move the cg foward a small amount? Otherwise do the rudder mod or change the tail moment.
Old 03-26-2009, 01:12 AM
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Default RE: Wild ride!!!

Well, had to scrap buying the extra wing plan, and on to plan B! Made a hot wire bow saw, some templates of wing ribs, and voila! My plan was to keep the span in the 8-9 1/2 ft range..., well, now I'm at 12ft 4inch span, with some polyhedral, but weight is up around 50 ozs. Not a problem I don't think though, still very light wing loading. My cutter is only 26 inches wide, so made 4 panels at 25 inches. Joined 2 panels with 5inches of dihedral in them, then joined these in turn to original wing set that has a few degrees of dihedral as well. Panels are removable for transport. Just hope it doesn't snap a panel in flight, this is my largest bird to date so far, but now I have more plans, muhahahah! If this works out, going to make a pure sailplane with 18-20ft span, use fanfold foam for building fuse to keep weight down, and find me a big freaking hill to lob it off of . I forgot how much fun fabbing and designing and building is, I love it! Especially with todays lighter glues like gorilla glue or even triple expanding foam. Shooting for 18-20ft span with same airfoil, 9 inch chord, all up weight of less than 2 lbs. But that's after this one reaches it's expiration date(might be tomorrow!) Thanks for any and all interest, will post some pics if anyone's interested.
Old 03-26-2009, 04:55 AM
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Default RE: Wild ride!!!

Got a picture of this contraption???
Old 03-26-2009, 01:10 PM
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Default RE: Wild ride!!!

Here is the monstrosity, it dwarfs the radians span. Took it out a bit ago! Ended badly though. Weather report called for 5 mph wind, gusting up to 10, they lied again. Went to the field, got it assembled, turned around to pick up radio and gust picked it up off the ground and flipped it right into me. My common sense said "just take it apart and try another day." My little kid voice said "Hurry! Wind'll die down in a second!" Well, got it all ready, a lull in the wind came on, off she went!!! It was beautifull for the first 10 seconds! Climbed at around 45 degrees, wings level as could be...then...WHOOOOOSSSHHH!!! Wind whipped up to at least 20mph [X(] AHHH! [X(]! It instantly pulled up into a half loop and then flipped rightside up again but going downwind. Cut the motor and just tried to fly it back. No use. With the now ultrashort tail moment the rudder was 100%ineffective. I pulled into another 1/2 loop, it righted itself, and was now coming toward me upwind. Wind kicked up again and pitch went crazy, up down up down...then a wing clearly started to oscillate back and forth. Nuts. POP! the wing panel seperated and drifted with the wind. The rest of the ship went knife edge so I just held full down and full top rudder. It spiralled with the wind for 2-3 hundred yards and piled in. Was a slow walk of pain, let me tell ya! Panels were ok, mostly, but fuse is toast. Snapped in 3 places, splintered all over, built up wing all busted up. Back to the drawing board though !
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