Smash Rocketry New Group Project – The Proton M

[smashburn]

No, Adrian, I do not. I was preparing to order some. If you are coming to the launch Saturday, I would be happy to take some from you. Since we live probably about 70 to 80 miles apart, the only other way to get any is to mail some. I do have some Rocketflite ignitors that I made up, still a little pricey, but they work good and I may go through a bunch of ignitors in running a success/failure test.

This reminds me, any idea of how long I need the tails on the ignitors for the finished product, Steve? 12″

Steve, if you ran some half inch pins through the mating plates, it seems that it might reduce some of the strain that will be put on the bolts, which might help prevent failure. What do you think?

From what James has told me of the Delta III Project Kevin did, they only used 4-6 bolts .. and that was considerably bigger than this. Here’s a pic of their early tests. Note they came in form the threaded end .. they corrected that in later tests and the final to come in from the Hex as to avoid hassles w/ the wires.

quote: “The major components will be held together during flight with
these bolts. The bolts are drilled and each packed with 1 gram
of black powder, then filled the rest of the way with epoxy.
The on-board electronics will fire the charges,
allowing the sections to separate. Here you can see a before
and after picture of a bolt.”

Bear .. 12″ seems a little short, depending on where the electronics are located. The ‘pins’ seem like a good idea to provide additional horizontal stability .. I hope to get all the motor/bulkhead assemblies built this weekend and will have a better idea of how it will all fit together.

[smashburn]

Here are, more or less, the 3 Proton Stages.

will extend the 3rd stage a little.

Booster is 60″, stage 2 is 48″ and stage 3 is around 72″. I plan to add fin and motor mounts to the 3rd stage for a potential 3 stage flight at some point. The critical issue of course will be getting the CP/CG right on all scenarios .. may be quite difficult. But I figured since we’ll be breaking it apart for recovery anyway .. why not.. plus the Motor Mount/Fin assembly will add some needed weight to the upper section.

[BEAR]

What size bolts did they use? The picture looks like a 3/8 X4″. I was thinking of something at least 2″ long, 1 1/2′ for two pieces of 3/4″ plywood and a 1/2″ for the nut. Easy to get longer, and/ or to start long and cut it down to any length we want. I can get 3/8′ bolts all day long, but 1/2″ and 5/8″ are more difficult.

[BEAR]

Steve, I presume the dimensions in your drawing are meters?

[smashburn]

Steve, I presume the dimensions in your drawing are meters?

yea .. that’s the original drawing we started with. We will vary slightly but close to that.

Still waiting for Kevin to get back with details .. but it may be 3/8″ .. feel free to pursue that. However I’m not going to spend any time reinventing the wheel when they have a flight tested and proven technique on an even larger and more complex rocket.

A more important design issue is the booster/outboard attachment detail and nosecone design. btw, Rich has recalculated all the dimensions into inches and the boosters will be 44″ long and the nosecones 12″ long. Our scale is 12.9.

[BEAR]

There is not a lot of wheel to invent here. The photos and the description almost says it all. Just need to know which size to work with so we can figure out the stress tolerances. When you think about it, all there is, is to drill a hole, put powder in, add a crusty wire, and seal it so the stuff does not fall out. The question is, will it support and exceed the stress that will be placed on it. Reduce the stress, and the less number of fasteners that are necessary. Have I missed something?

[smashburn]

There is not a lot of wheel to invent here. The photos and the description almost says it all. Just need to know which size to work with so we can figure out the stress tolerances. When you think about it, all there is, is to drill a hole, put powder in, add a crusty wire, and seal it so the stuff does not fall out. The question is, will it support and exceed the stress that will be placed on it. Reduce the stress, and the less number of fasteners that are necessary. Have I missed something?

Just size of bolt, size of hole, depth of hole, amount of BP, type of ematch, seal material, number of bolts, to score or not score the outside (don’t think he did), torque on bolts, thickness of bulkheads .. all worked out by them already. You’re results will likely be fine, but I am more comfortable going with his “flight tested, flight proven” technique. Like I said, go ahead if you wish but it seems a waste of ematches and bolts ($$$), and I’m going with Kevin’s design in the end anyway. We’ll go through enough ematches and bolts as it is later on testing our assembly.

[BEAR]

Your call. I see it as a different rocket, different weights, different aerodynamically induced stresses, different number of bolts, different configurations, new wheel. Where do you start? You can make everything identical to Kevin’s and still have to make it different. Again, your call. I have enough other things to keep me busy until you have it figured out and we start on prototyping and manufacturing. I look forward to seeing more details of Kevin’s so we can reproduce them to see how well they meet the needs.

[Dr_J]

Great project. Fun to read. A long time ago I made these pyro-bolts:

The brass part has an undercut. The stainless bolts are just igniter holders. The advantage of the brass is that they are relatively strong before breaking. Here is a drawing (sorry… metric):

More info here: http://www.nerorockets.org/nero/neh-projects-e36-para.htm

Jeroen

[BEAR]

That is very interesting and gives insight. Thank you for sharing this with us.

I would like to express the same with Edward in regards to his sharing his line cutter also.

[Author]

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