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Missile Construction Question

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Missile Construction Question

Postby Ramius-II » Thu Jan 08, 2009 9:49 pm

Hi All! :D
I have been trying to follow the June 1995 Issue 21 article by Mathew Spade on constructing missiles. In the article he writes "Next, drill a 1/6th inch hole in the bottom of the missile and slightly counter bore the hole." If my calculations are correct, 1/6th inch hole is .166 decimal or a #19 drill. This seems very large to me. Has anyone actually built a missile or missiles following this article and is this a correct and valid size hole or did I do something wrong?

Thanks, Ed
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Postby wlambing » Thu Jan 08, 2009 10:44 pm

Ed,

1/16th inch is 0.062.

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Postby Ramius-II » Fri Jan 09, 2009 1:25 am

Thanks and the article says one-sixth of an inch which seems very large.
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Postby wlambing » Sat Jan 10, 2009 12:10 am

Ed,

I just reread the article. I think we have a recurring typo for that fraction! Some thought food; There's butt-tons of 1/16 stock in our little universe and I suspect only two lengths of 1/6, stored somewhere in the vaults of Lower Slobovia. I also supect those pieces are made of Nonobtainium. ;^)

If the hole (nozzle) in the bottom of the missile is much bigger than 1/16 you'll not get too very much thrust from the gas expanding through same.

Take care,

Bill
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Postby Ramius-II » Sat Jan 10, 2009 1:25 pm

Hi Bill! Thanks. Where I get confused is when I look at the pictures in the article it looks just as you said, about 1/16th inches. I was given some Estes rocket motors (1/2A6-2) by my neighbor and the exhaust holes are about 1/6th of an inch! My intent is to incorporate the proper size o-ring in the tail of the missile as a seal against the "pin". Here is a drawing of the missile with a 1/6th hole. What do you think?

Best, Ed
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Give Matt a call

Postby Mike Dory » Sun Jan 11, 2009 7:22 am

Guy's - You might just give Matt a call. He's always been willing to help others. The last phone number I have for him is (770) 929-1945. You won't find a better man. Best Wishes..... Mike Dory
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Postby wlambing » Sun Jan 11, 2009 2:54 pm

Ed,

I thought you were going with a gas ejection system. Matt and Dr. Art Broder have good experience with missiles. If you're going to use Estes motors, that's a whole different world. I remember years ago when Loren Perry burned the bow of his USS Long Beach (CGN-9) using the smallest Estes motors for A/A missiles. It was sad!!

Good luck, I'm going back to sleep now!

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Postby Rogue Sub » Sun Jan 11, 2009 2:58 pm

I seem to remember watching a video where Mike was talking about how his rocket motor missile went through some lady's house and ruined her carpet.... Dont quote me.

Bill I am the one using a gas ejection system.
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Postby Ramius-II » Sun Jan 11, 2009 5:00 pm

Hi Guys! :)
Thanks to all. Yes, I am using a gas system and I was only looking at a rocket motor to see what size Estes used. The plan is to incorporate an 0-ring seal in the base of the missiles.

Best, Ed
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Postby wlambing » Sun Jan 11, 2009 5:05 pm

Kevin,
I know you're using gas. That's why I'll have my trusty and faithful MK V mask with the heavy duty cartridges installed!!!! :shock: :lol:


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Postby Ramius-II » Sun Jan 11, 2009 8:06 pm

Hi All!
First, thanks Mike I called Matt Spade, we had a great conversation and I learned a lot! He sends his greetings and best wishes to everyone. The answer is 3/32" or .09375. Matt started with 1/16" and found that 3/32" worked better. For all those developing missiles, one piece of valuable info is that a missile will work very different when launched from underwater than in plain air. "In plain air a missile will appear to be very disappointing, while launched from underwater will work amazingly!"

Best to All, Ed
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Postby Rogue Sub » Sun Jan 11, 2009 8:44 pm

As you may or may not know I have been makin a missile system for my ohio. Here is a look at how it works so far. I have been launching the missiles using 60psi and liquid air for propellant in the missile. The cylinders are 4" long and about 3"- 2.5" nominal gas space inside. Overall Missile length with balsa nose cone is 5". The exhaust port is 1/16" with a taper bore nozzle and o-ring seal. For my testing I am using air from my compressor to launch, later I will use propel on board, which has a pressure of about 70psi at around 70 degrees F. Right now I am test launching out of a bucket and getting small heights. To increase my height I am going to reduce weight by cutting down on bulkhead thickness. this will not only increase my gas volume but also decrease weight. A 3/32 nozzle is also interesting. Now for some photos and a movie!
Sorry If I jacked your thread Ramius I will move it if you like :)

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Image
[/youtube]
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Postby Rogue Sub » Sun Jan 11, 2009 8:48 pm

Kevin
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Postby expfcwintergreen » Sun Jan 11, 2009 8:50 pm

Kevin with increased gas volume.... great....
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Postby Rogue Sub » Sun Jan 11, 2009 9:05 pm

Yeah believe it buddy as you type at this moment I am killing the dogs.
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