Blast Plate Designs

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Mike

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I was in the model shop not too long ago and knowing I wanted to make a blast deflector I bought some Aluminium 10" x 4". I was wondering what would be best way to turn it into a blast plate.

The most that will probably launch off it it clusters of Estes D12s.

Thanks in advance.
 

powderburner

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I am afraid you will quickly get burn-throughs with aluminum, especially if it is thin (2-3 mm or less).
 

jflis

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I agree with the comment about steel vrs alum...

I've even used 1/4" aluminum and had it burn through after a while. Steel would be your best choice. If you want to go *real* cheap, yet reliable, get one of those galvanized steel plates that are used to cover electrical boxes. Knock a hole in the center and you're ready to go.

If you do get some sheet steel, I've attached a drawing of a simple blast deflector that I've used on occation.

jim
 

mtmind

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I'm going to make a blast deflector from Durhams water putty as soon as I get a nice day outside. The stuff is used in making nozzles for amateur motors so I figure it should hold up to the heat pretty well. It's going to be a kind of "concave cone," that is, if I don't screw it up too bad. I plan to put a hole in the center of the paper plate for the launch rod tube. This is a piece of T-2+ from Totally Tubular through which the launch rod will extend. It should be able to fit a 1/4 inch rod but I'll only need 1/8" and 3/16". The tube is lined up perpendicular to the plate and glued in place so that the putty won't run out the hole in the bottom. Then I just build the putty up aroud the tube so that the outer shape is where I want it. I don't have experience with this putty myself yet so I don't know whether it will need to be built up in stages or if one big glob will hold the shape from the get-go. The putty is supposed to expand slightly when it hardens and this should mean that it doesn't crush the tube inside. The picture is shoddy, I just did it now, but everything's labelled.

Peace :cool:

Mike
 

cls

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some other ideas:

an auto brake drum works if you can find one. also a brake rotor, although the center hole may be too big.

I've seen old grinding disks used as blast deflectors... no circular saw blades though!

and you can use a flower pot if you have one lying around ...

too bad AOL CDs don't work that well :)
 

Zippy

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Christmas Cookie lids & cans. Gallon paint can lids.
 

Ryan S.

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my club uses grinding disks. They already have a hole in them and they are resistant to heat. They may have replaced them, but it is what they used to use
 

Johnnie

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I have used rain gutter elbows, which at motor start up, directs the blast down and away, and helps with not having the blast cook the bottom of your rocket.
 

jflis

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Originally posted by gerbs4me
I heard you can use a coffee can
Yep, i've done that often too. Specially if we built a quick setup in a classroom as a part of a rocketry class.

Here's a link to a simple setup that uses a coffee can for a blast deflector:
https://fliskits.com/products/free_dl/simple_pad.pdf

basically, you cut out the top and bottom of the can, then you cut the remaining tube in half. You then take one of the halves and crease/fold it along its center to form your blast deflector.

simple, cheap and easily replaced (heck, you get TWO out of each can :) )
 

Mike

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OK so I won't use the aluminium, I'll have a look tomorrow to see if they have any steel sheet. They definatley had brass, would that work?
 

sandman

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Mike,

Go to a local "ironmonger", you Brit will know what that means and buy an olf fasion metal funnel. About 50 pence.

sandman
 

Steward

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In my youth...I built a (somewhat credible) gantry on a small platform, with a set of ball bearing rollers. By using a stainless steel plumbing "elbow" I guess... about two inches in diameter... curved, and about 12 inches long... It chaneled the engine exhaust out and against a wall of the structure... that actually pushed the gantry away from the launch rod....
It didn't weigh very much...(made from plastic spools found at the fabric store).....and moved quite easily....
Really fun to do and fun to watch the "real type" liftoff....
I have a picture of the tower...but don't have one of it working...this was long before cameras were invented...LOL
 

powderburner

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My vote is for simple, fast, cheap, light, and easy (anyone wishing to steer this line of thought toward the subject of 'women' can start a different thread).

I like a piece of sheet steel just big enough to do the job and not much bigger. Scrap stuff is fine. I like one little hole to slide the deflector over the launch rod. End of design.

I do not like a big block of ceramic or other material that costs me $5 and that I have to carry out into the field with the launcher (sorry, even if they work nicely, I'm too lazy).

I like something that if it gets lost in the garage, or the kids ruin it while digging holes in the back yard with it, or if it burns through, it's no big loss.

An overlooked source of thick (1/8 inch or so) plate stock is your local welding shop scrap pile. I got several discs (approx eight inch diam) roughly cut out for me for $5 a couple years ago. Catch the shop guys on a slow day, and they'll probably be quite willing to help you out.
 
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