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Originally Posted by barone
As I've got it built, the model weighs in at just over 8 ounces without the motor mount and motor (glide weight). Currrently, replacing the nose cone so I can try another launch. Was planning a lower impulse F but if you think an E15 would be adequate, I can give it a try. Of course, if that works, then the design needs to be changed to accomodate a 24mm motor. That might help with stability but probably more weight will be needed for the glide. Or, the up elevator can be adjusted down......Hhhmmmmm......maybe I should lessen the elevator instead of adding weight? Ok....let me see if shimming the elevator so there isn't as much will help. Sounds logical. Going to have to give it a try.....
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Heck at 8 ounces, even an E15 is sort of overkill.
A the very least, you can test fly it on a D12. A D12 can put a pound of anything up a hundred feet or more. And if things go badly on boost, good thing it is only a D12. If it goes very well, then you can try an E11 or E15.
As for accommodating a 24mm motors, well, a 29mm fits, so all you need is an adapter. Where the real problem of fitting a motor could be if anyone wanted to use a 32mm RC casing in order to use an F13 or G12 reload. Ok, I just realized you probably meant keeping the adapter inside, and only ejecting the engine, in which case you would need to modify the model to work with ejecting a 24mm motor, but that would be a good thing. Then you’d have less o a CG shift from liftoff with loaded motor to glide when the engine ejected. Which then would mean for a desired CG for glide, then the CG would be LESS AFT for boost, which would make it more stable.
I really do think that second 180 degree turn (when it went from pointing down to pointing up) looked more like an unstable flip than a pitch-loop. When a RBG does loops on boost, or half-loop into the ground, it tends to be close to a constant radius once it gets enough airspeed going, where more speed just means it loops faster rather than tighter.
Also, possibly that F25 got it moving so fast that the elevons fluttered. That is probsbly the FASTEST that design ever went. Like putting an Aerotech D13 into an Astron Space Plane.
As for adjusting for weight, definitely simply reduce the elevon angle to work with an E15 or D12, instead of adding dead weight in the back to make up for the weight difference from an F25. Take note that the adapter mount will add something there too. Then you’d have less for a CG shift from liftoff with loaded motor to glide when the engine ejected.
- George Gassaway