Broken Rocket Revenge

[Bone Daddy]

I've been working on a little bright red rocket with heart shaped fins for my sweetheart (ahhhhh). I decided to use a streamer for recovery and with that in mind went off to the Mansfield Rocket Range (actually Mansfield Sports Complex). Suffice to say, my working knowledge of streamer recovery was not vast. I got off three flights, but not scott free. After each flight I had to do some fin repair. The third flight resulted in more little balsa chips than I wanted to deal with. It was then, I had an epiphany.............................

I looked at the broken little bird and thought, Hmmmmmmmmmmmm I've flown rockets with less fin area than this. So I loaded up a 1/2A and bam, a really nice flight with no damage on recovery! It was at that moment that I realized I needed to build prebroken (and artificially distressed) rockets. Thus was born Bird in Hand. I flew her three times today. Twice with a streamer - still working on that and once with a 12" chute with a large spill hole.

The last flight - on an A8-3 - with the chute was especially telling. It was fairly windy and as I watched Bird in Hand drift towards Earth, I realized she was going to clear the fence hit the parking lot. When I got to the parking lot, there was Bird in Hand being dragged by her parachute across the asphalt - with no damage except a worn spot on her fin tip!

 

[Rocketcrab]

I hope you don't mind a little un-asked for advice - but I couldn't help but notice that in looking at picture #3, the leading edge of your fins isn't with the grain of the balsa. Your fins will be a lot stronger if you cut them in that fashion. I like the design of the red rocket, too!

 

[Evo666]

^ That was what I was thinking too about the grain going the wrong way.

 

[powderburner]

Actually, I'm not so sure that Bone Daddy's fin grain isn't just fine. As long as it extends in some general spanwise direction between leading edge and trailing edge, it ought to be capable of carrying spanwise loads to the fin root. There would definitely be a problem if the balsa grain ran parallel to the root, as balsa doesn't have much bending strength in a cross-grain direction. What appears in the picture looks like it should be OK. A rough landing could tear up anyone's fin tips if the rocket lands hard on that exact spot.

 

[Bone Daddy]

Thank you for the comments they are always welcomed. And, indeed you are all right.

When I had the flash of heart shaped fin inspiration, I quickly put something together to see what it would look like - I always build a prototype first, that usually becomes the onlytype. With the fins sweeping under the rocket I knew that grain was my enemy - anyway it ran it would be weak somewhere. It didn't help that I like using thin balsa wood - easier to cut, I'm lazy that way. But I did really think it survive a flight or two.

I actually liked the look of this one enough to build a nextotype that I christened (drum role please......) Heart Attack II. This time I addressd the grain problem head on. I've solved the problem in the past using paper reinforcement. This time I went classy with the grain running perpendicular to the stress line.

She has yet to fly. I've been saving her for a club launch - which have been rained out since September. I will use a 12" chute thought rather than a streamer.

I'm also building a booster for her (know cleverly known as Double Bypass). I didn't bother to correct the grain since I consider it to be expendable. It'll fly on a B6-0 and a 1/2A. I really hope they bring the A booster back.