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spudgun range, are we falling short?

A place to ask general spud cannon related questions.
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Unread postAuthor: LeMaudit » Sat Apr 30, 2011 6:09 am

After a few trial and errors I think I feel now better how to turn and mill UHMW.

I will also be able do slow-mo footage. If velocity was around 50m/s over a distance of 3m and I filmed at 420fps, I should get 30 frames of the projectile and sabot.

Sound great!


the thinnest of ali plates should be enough as a backplate - polished of course

Ah! Now you're talking!
The thinnest of the plate is whatever I cut from the metal rod ;-)


What are the dimensions of the rectangles and plug thickness?

You like dimensions way too much dewey :D
in mm, so far:
plug thickness in 13.1. petals are 29.3x98.8 cut from 1/4" plate
But I'm going to mill them some more, so don't draw it yet ;-)


Why not use adhesive backed aluminum tape. It could be replaced easily enough or even double layered if required.

Please don't be rude! ;-)
Really not a problem to make a thin metal cup. Nothing would adhere really well to UHMW but I guess some tape could work for a single shot, yes. The advantage of a metal cup would be to remove some stress from the plastic plug. It could be tear at the slot angles I'm afraid, in particular when the plug exist the barrel and the petals separate. A cup would protect from that stress nicely. I'm going to try to make a thin and rigid one with some grooving (groovy!) and see how much it weight. If it's a few grams I'll cut a recess in the plug for it and maybe make it less thick.

I know, I know... I could compute the theoretical weight... but that's not fun ;-)
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Unread postAuthor: dewey-1 » Sat Apr 30, 2011 1:01 pm

LeMaudit;
I needed to find out what the specific gravity is for the UHMW that you had.

I was using .95 based on typical specifications but yours is about .934.

The CAD program will calculate volume for me so that I can derive the weight for the individual pieces.

I got my version of "hinged" sabot down to about 39 grams with out hardware. Note the 4 detents and pins to hold MiniBoy.

edit: got it down to 39 grams by enlarging holes from the original 46.
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Unread postAuthor: LeMaudit » Sat Apr 30, 2011 1:26 pm

I needed to find out what the specific gravity is for the UHMW that you had.

No need to justify... to each is own madness :D


I got my version of "hinged" sabot down to about 46 grams with out hardware. Note the 4 detents and pins to hold MiniBoy.

Lots of holes... niceeee....


Here's a shiny disc I just finished. Weigth is 4.2 grams. Not bad, it's very rigid, I think I can remove some UHMW.
Image
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Unread postAuthor: LeMaudit » Sat Apr 30, 2011 6:21 pm

The aluminum plate is fitted to the UHMW plug, and I shaved some weigth while I was at it... minus 5 grams! Yes!!

Image

Image

Image
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Unread postAuthor: MrCrowley » Sat Apr 30, 2011 6:23 pm

Looking very good indeed.

Oh by the way, awhile back you said that a caulking tube should fit perfectly in my barrel. Well, I tried that out yesterday and you were right :wink:
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Unread postAuthor: LeMaudit » Sat Apr 30, 2011 6:38 pm

haha! That's a powerful source of ammo you have there ;-)
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Unread postAuthor: LeMaudit » Sat May 07, 2011 7:18 pm

I'll continue the update of the sabot in the Miniboy thread
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Unread postAuthor: dewey-1 » Mon May 23, 2011 10:59 am

I came across something interesting for premade fins for a projectile.
It is used on arrows but it may have a use for our type of projects.
No one has posted about it so I thought. why not.

http://www.starrflight.com/how.php
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Unread postAuthor: LeMaudit » Mon May 23, 2011 11:35 am

This looks interesting.

It kinda remember me similar fins that where used during WWII for mines, lauched against submarines from hydravion in the Pacific war...

I know because I made them as 1/35 resin models :-D But can't remember the name of the bomb to find a picture. Maybe JSR will know that?
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Unread postAuthor: dewey-1 » Mon May 23, 2011 12:02 pm

Here are some German WW2 variations you might be thinking off.


http://commons.wikimedia.org/wiki/Categ ... pped_bombs
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Unread postAuthor: LeMaudit » Mon May 23, 2011 12:06 pm

Look like that, but forgot to say it was an allied bomb.
Damn memory... :?

[edit] Now I remember!
It was retro-rockets fired from Catalina airplanes against Japanese subs during the Pacific war, that had similar fins. It was not a bomb dropped from an airplane, really it was like a rocket.
I did a model 1/35 scale for casting in resin but it was a private commission and I didn't kept anything... except the master :-D
Anyway nothing of importance really, except my old brain now can rest ;-)
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Unread postAuthor: dewey-1 » Mon May 23, 2011 12:59 pm

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Unread postAuthor: LeMaudit » Mon May 23, 2011 1:10 pm

Yup. Those rocket I think I remember were kinda prototype, an experiment. I'm not sure really the exact context, I did that 8 years ago :?
I doubt the info about those Catalina rockets is somewhere on the internet, if you can find any, kudos to you! :D
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Unread postAuthor: dewey-1 » Mon May 23, 2011 1:55 pm

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Unread postAuthor: LeMaudit » Mon May 23, 2011 2:24 pm

Ohhhhhhh :cheers:

I'm most impressed!
Yes, those Mousetrap/Retrorocket look exactly like the right deal:

Image

They were attached to rails under a Catalina for deep bombing.

And I found my model in an old box in the meantime :D

Kudos to you!!!
:wav:
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