I don't know if it's appropriate to ask here, but I was wondering what a good payload design would be for launching an egg. The egg itself will be housed in a BT-80 perpendicular to the axis of flight. The question in mind is for the upcoming TARC competition, so any help would be brilliant.

My team uses a short, ~8" long piece of BTH-80 as a payload tube, with a thick piece of soft foam (~0.75" thick) mounted in the base of the payload bay. The egg itself is first put in a plastic bag (Always do this!!!), then has two small piece of foam put on either side of it to keep it centered, after which the egg is placed inside a BT-80 tube coupler. Two more pieces of foam would go above and below the egg, inside the tube coupler, and then the entire tube coupler assembly is put into the body tube. One last piece of foam caps off the top, and then the nose cone keeps everything together. This setup has survived a ~20 fps descent straight onto a paved road and came out fine (the balsa nose cone, alas, did not).

In general, as long as you've got a way to hold the egg tight enough that it will not bounce around during flight (I always shake around my payload section before to make sure the egg is not loose at all), and has enough padding around it to dampen vibrations (an enough padding along the axis of ascent/descent to cushion the egg during these high-acceleration phases), you should be fine.

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David Hash
NAR#77967
http://www.Semroc.com

Awesome! Thanks for the advice. So I assume that I'll see you in Virginia?

I sure hope so! My team has always seemed to be plagued by awful luck during our qualifying flights. To give you an idea, we went out to launch 2 weeks ago, and hoped to make our qualifying flights that day. Our second flight hit 759', 46 seconds. A bit of adjustment, and the next flight went 742'. One last tweak and our fourth flight hit exactly 750', 44 second duration. Sound like things were all square for a qualifying attempt? They did to me! Making sure not to change everything (rocket mass was within 2 grams of the previous flight, and motor weight was within 0.1 gram), we declared the next flight to be a qualifying attempt. Naturally, it went 732', and stayed up 37 seconds.

Our best guess is that upper-level winds were causing excessive weathercocking. We've still got one attempt left, and we're going to be flying this weekend, hopefully getting in a decent flight.

So, hopefully

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David Hash
NAR#77967
http://www.Semroc.com

Ah, that's a shame. So what are the requirements to qualify?

In years past, I think scores less than ~15-25, but of course, it varies every year (I wonder if anyone's graphed it to see if it's gone down with increased participation). With a score of 44, I don't think our first qualifying attempt has any sort of chance (I would have felt much better about the 2 from the previous flight).

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David Hash
NAR#77967
http://www.Semroc.com

I see. Sorry if it seems like I'm asking too much about your rocket, but what motor do you guys use?

Cluster of 2 E9-6's and 2 C6-5's (in theory, to diminish the effect of batch variations between individual motors, and also let me pick and choose between them to get them all to add up to the same weight).

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David Hash
NAR#77967
http://www.Semroc.com

Very neat. OK, thanks for the help.