Posted: Mon May 23, 2011 2:26 pm
New pengun ammo? 
Geez... I didn't thought about that... now JSR will FAP againLockednloaded wrote:New pengun ammo?
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Posted: Mon May 23, 2011 2:28 pm
Posted: Mon May 23, 2011 2:53 pm
No.LeMaudit wrote:Geez... I didn't thought about that... now JSR will FAP again
But now you have to make a nano-boy for a future project
Posted: Mon May 23, 2011 3:11 pm
Fair enough. Never abuse good things...No.
Well, this retrorocket was collecting dust... It's about 4mm diameter, a tad smaller than a BB pellet.... I could fire itBut now you have to make a nano-boy for a future project
Anyone know a nice <s>bïtch</s> beach?
Making a little mold for miniature lead ammo would also have some appeal
I already have some brass casing:
Posted: Mon May 23, 2011 3:16 pm
LeMaudit wrote:I already have some brass casing
MUST HAVE LATHE AAAAGH!!!!!
Posted: Wed Jun 01, 2011 9:43 pm
Bump
After a little bit of penetration testing, I have decided to fire my custom made round for distance. The problem I am having is that I do not know how to calculate the drag coefficient. I thought you guys might be able to help. The rod is 3/8" in diameter by 10" long with 3, 2.5" by .75" fins welded on to it. I realize the probability of recovery is very low but a drag estimate would be useful. If you need any more information, let me know.
After a little bit of penetration testing, I have decided to fire my custom made round for distance. The problem I am having is that I do not know how to calculate the drag coefficient. I thought you guys might be able to help. The rod is 3/8" in diameter by 10" long with 3, 2.5" by .75" fins welded on to it. I realize the probability of recovery is very low but a drag estimate would be useful. If you need any more information, let me know.
Posted: Wed Jun 01, 2011 11:53 pm
A bit difficult to calculate, is usually determined experimentally.
Looks like it will go far though, what are you shooting it out of? And what does the sabot look like?
You could make your own wind tunnel, this is from 1942 - when men were men and carved their own propellors!
Looks like it will go far though, what are you shooting it out of? And what does the sabot look like?
You could make your own wind tunnel, this is from 1942 - when men were men and carved their own propellors!
Posted: Thu Jun 02, 2011 12:05 am
Isn't irisher's projectile too tail heavy?
Posted: Thu Jun 02, 2011 12:38 am
... but the fins are pretty huge so the centre of pressure is very far back.MrCrowley wrote:Isn't irisher's projectile too tail heavy?
Posted: Thu Jun 02, 2011 7:15 am
I actually thought it would never work after I measured center of gravity but I have had great success with this round. The sabot system is short dowel wrapped in duct tape as the pusher plate and carved Styrofoam as the guides. I am firing this thing out of my 1.5" sprinkler gun.
Posted: Thu Jun 02, 2011 7:49 am
Videos/photos please!irisher wrote:I have had great success with this round.
Posted: Thu Jun 02, 2011 12:03 pm
Here is the CP based on 1/8" thick fins.
The CG should be at least one caliber 3/8" ahead of CP.
irisher, where is the actual CG?
The CG should be at least one caliber 3/8" ahead of CP.
irisher, where is the actual CG?
Posted: Thu Jun 02, 2011 3:43 pm
The center of gravity is exactly 6" from the tip. I made some holes in 1/8" plate steel but the fins never actually get through. It will bury itself approximately 5.5" into solid wood and is quite annoying to get out.
Posted: Thu Apr 19, 2012 12:36 am
Just over a year since this thread was started and not that much progress 
MrC, what are the chances of fitting a smaller calibre (25-35mm) barrel to your hybrid? If you could shoot stuff with those dimensions I could perhaps cook up some less elaborate projectiles with relative ease, something that would be more likely to be fired and it would not be a tragedy if they were never found.
MrC, what are the chances of fitting a smaller calibre (25-35mm) barrel to your hybrid? If you could shoot stuff with those dimensions I could perhaps cook up some less elaborate projectiles with relative ease, something that would be more likely to be fired and it would not be a tragedy if they were never found.
Posted: Thu Apr 19, 2012 12:59 am
Shouldn't be too difficult, I have some ~25mm iron pipe in the garage although it does have a seam running its length. I wonder if it would be best used on my smaller burst disk hybrid: faster opening time and convenience vs. greater flow and larger chamber volume.