First, do you have the original kit? If so, I know why you want to upscale it. If not, get it, build it and then you'll really want to pull it off.
This kit was my first 'hard' kit. I got it as a Christmas gift and after looking at the picture and the parts in the bag, I quietly put it away for a while. I was intimidated. But, some 6 months later I had a weekend to myself and nothing to do, so I thought I'd give it a serious try and I am glad I did.
The kit involves a few techniques that are more than the typical 3FNC builds. There are a few paper transitions, various detail parts and a neat set of gussets on the motor mount. I simply followed the directions and over a few days, had a really great looking rocket. In all honesty, though, I balked at the painting, so it still sits covered in plain white on a shelf where it won't get damaged. I need to do the paint and fly it, though, as it was a great build.
So, as far as BT-80 goes, I don't see why not to try it. The transitions etc can be scaled with free software, the rocket seems like it has a good length to weight to fin ratio by eye, so I be getting it stable should be easy. I agree that a 29mm MMT is not a bad idea. Although there is a 24mm F32 from AT right now that could also work on a heavier rocket.
Lastly, the dowels are probably going to be tough as Ted mentioned. I also like his idea of making them intentionally break away on impact vs just fiberglassing the heck out of it. To do this one right, I think keeping the aft weight in check is better than getting it too heavy back there and then adding nose weight. The other option could be a separation method where you break the rocket into 2 pieces and bring the back down on its own, oversize chute.
Just some thoughts. I'd like to see it done, so I hope others chime in with good ideas.
Sandy.
