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Unread postPosted: Tue Aug 04, 2009 1:41 am
Author: starman
Good job on your return to hybriding! Very solid machine there...great sound!! You must get a chrony or even an acoustic velocity measurement.

OK I'm dense...I don't get your ignition method there. Looks like an old cannon prick/fuse hole but I know that wont hold up to pressurized hybrids. What's going on there?

Yes, I'm still awaiting the watermelon shot... :wink:

Unread postPosted: Tue Aug 04, 2009 4:43 am
Author: theBOOM
Starman it's a spark plug.... One of the electrodes is the chamber and the other one is this wire which has been somehow sealed inside this fitting... I wondered what it was that you used spudfarm.. looks like teflon tape or something... Care to elaborate a bit :P?

Unread postPosted: Tue Aug 04, 2009 12:20 pm
Author: SpudFarm
starman wrote:Good job on your return to hybriding! Very solid machine there...great sound!! You must get a chrony or even an acoustic velocity measurement.

OK I'm dense...I don't get your ignition method there. Looks like an old cannon prick/fuse hole but I know that wont hold up to pressurized hybrids. What's going on there?

Yes, I'm still awaiting the watermelon shot... :wink:


I have a chrony :P I did shoot some today, i planned three shots, so i made three burst disks. the first shot went good enough, i think it was a bad mix. but atleast it did some damage. It hig the first speaker and turned it into twisted metal and went through all the other ones.
it still went to fast for the camera after passing through everything.

the projectile was a battery (one of the biggest ones i can get) with alot of cloth as wadding around and behind it. bad choise since the barrel has a thin film of molten golfball in it and that builds up ALOT of friction.
I also think the cloth was blasted past the projectile since it had a ton of battery sized holes in it.
The chrony told me 830fps with 200g projectile, 32layer disk and 5x wich dissapointed me a bit, but still pretty fast.
HGDT was pretty far off with 470m/s though.

The reason i only did one shot was that the second had a faulty disk, so i changed it and charged again, this time i forgot to attach the barrel.
(I admitt it, i am a moron after such a long time without spudding)

The cannon will get some rest since i got REALLY pissed off at myself when i did not attach the barrel.

Oh and the chrony somehow mesured 480m/s on that shot :S


The sparkplug is a 3/4" male endcap (Brass) with a hole in it. a welding electrode with shrinking tube was inserted and bent so it almost touches the edge of the endcap on the inside. the cap itself is filled with molten plastic.

the ignition itself is the same as before just portable, a camera cap dumped into a coil. the only change is that i made the circuit wireless so i don't need all those wires.


I do plan on shooting a rocket engine on a steel plate above a fire, but i don't think i can post that here. you know where to look ;)

[youtube]http://www.youtube.com/watch?v=NMYBnMoXwGA&fmt=22[/youtube]

the chrony ws 2m from the muzzle.

To much text here :P

BTW, listen to the sound of this shot and compare it to the golf ball shot. first time ever i have heared the sonic boom as clear as that.

I will now start adding videos here. I have since yesterday done one 5x blank to test the new union and a 5x with a lead slug.

Still have not forgotten the melon, I will try to do it before the weekend.

Edit: videos are on front page OFC

Edited by jrrdw.

Unread postPosted: Wed Apr 07, 2010 11:17 am
Author: SpudBlaster15
I knew you'd eventually regain the urge fire this launcher; it's a miracle you haven't blown off any fingers pursuing "other" interests. :D

Unread postPosted: Wed Apr 07, 2010 11:57 am
Author: SpudFarm
SpudBlaster15 wrote:I knew you'd eventually regain the urge fire this launcher; it's a miracle you haven't blown off any fingers pursuing "other" interests. :D


I can't allow it to rust down, now it is in a pretty practical condition.

I had to keep my fingers for now :P But it is strange that I never had any accidents. Glad for it though.

Unread postPosted: Thu Apr 08, 2010 12:50 pm
Author: SpudBlaster15
SpudFarm wrote:One more, hybrid topics needs to be bumped since no one looks at them otherwise.


Yeah, it's kind of a shame that hybrid cannons aren't more popular. In the 6 years this site has been around, only 96 topics have been posted in this forum, which equates to about 1 cannon per month. Compare that to the combustion showcase, which gets one new topic every ~3 days, and the pneumatic showcase, which averages nearly a cannon per day. Complex launchers just don't appeal to many people.

What camera did you use to film the recent golf ball shot? Casio EX-F1? Supersonic golf balls sure look great at 1200 frames per second.

Unread postPosted: Thu Apr 08, 2010 1:06 pm
Author: SpudFarm
SpudBlaster15 wrote:
SpudFarm wrote:One more, hybrid topics needs to be bumped since no one looks at them otherwise.


Yeah, it's kind of a shame that hybrid cannons aren't more popular. In the 6 years this site has been around, only 96 topics have been posted in this forum, which equates to about 1 cannon per month. Compare that to the combustion showcase, which gets one new topic every ~3 days, and the pneumatic showcase, which averages nearly a cannon per day. Complex launchers just don't appeal to many people.

What camera did you use to film the recent golf ball shot? Casio EX-F1? Supersonic golf balls sure look great at 1200 frames per second.


I totally agree. Earlier, hybrids where promoted as nuclear devices that only needed to be looked at to kill the user. That is to bad really, Hybrids are not that complicated either. My metering system is now fool proof and simpler then a meter for en advanced combustion, probably cheaper to..

Yes I do use the EX-F1. It is something you must have when spudding!
I was hoping the cannon had atleast a small muzzle flash so I where disappointed by the shot. I did capture a supersonic ring of condensed air though. When the sun peeks at me while I am shooting it I might be able to use higher shutter speeds and get a clear view of the projectile.
Perhaps flour behind the projectile would make a decent video?

I can't wait to fire a decent APFSDS round while filming it at 1200fps.

Good that we still have the spirit then ^^

Unread postPosted: Thu Apr 08, 2010 1:18 pm
Author: SpudBlaster15
I'd love to see steel ball bearing or marble grapeshot filmed at 1200fps.

Unread postPosted: Thu Apr 08, 2010 1:40 pm
Author: SpudFarm
SpudBlaster15 wrote:I'd love to see steel ball bearing or marble grapeshot filmed at 1200fps.


I will try to do the marble grapeshot tomorrow. Might be a problem that they break in the barrel, hope they break before denting my barrel...

How would you like it filmed? Angle I mean.
I might get a few 70 pound blocks of clay tomorrow, if that's the case I will have priority on a hollowpoint lead slug.

Unread postPosted: Thu Apr 08, 2010 1:53 pm
Author: SpudBlaster15
For the angle, maybe have the camera set up near the end of the barrel, aimed slightly downrange. Hopefully, that would allow it to effectively capture both the cluster of rounds exiting the barrel, and the spread pattern as the marbles travel toward the target.

Unread postPosted: Thu Apr 08, 2010 2:36 pm
Author: SpudFarm
SpudBlaster15 wrote:For the angle, maybe have the camera set up near the end of the barrel, aimed slightly downrange. Hopefully, that would allow it to effectively capture both the cluster of rounds exiting the barrel, and the spread pattern as the marbles travel toward the target.


I can't have a "down the barrel" view because of the smoke from the muzzle.
I can do something like the second GB shot.

Unread postPosted: Thu Apr 08, 2010 2:36 pm
Author: CpTn_lAw
I'd say far behind, zoomed in but still allowing to see barrel, focused on the target. That gives the best result IMO... I will be able to make a video comparaison, of a single marble filmed at 1200 fps, just for scientific purpose ^^

Unread postPosted: Thu Apr 08, 2010 4:39 pm
Author: SpudFarm
CpTn_lAw wrote:I'd say far behind, zoomed in but still allowing to see barrel, focused on the target. That gives the best result IMO... I will be able to make a video comparaison, of a single marble filmed at 1200 fps, just for scientific purpose ^^


I can't use the zoom to much since it decrease the light sensitivity. I always try to use as high shutter speed as possible.
You can se the difference of a side view and a "down the barrel" view in my most recent video.

It looks like I get the clay tomorrow to. Lead buckshot and slugs will be shot and mabe a golf ball and marble grape shot.

Unread postPosted: Thu Apr 08, 2010 5:28 pm
Author: CpTn_lAw
you know you can do a 60 fps photo capture and set the shutter speed to be very very high? this will (granted with a little chance) hopefully give very good full-res results.
(I did that two years ago and it worked)

Unread postPosted: Fri Apr 09, 2010 5:20 am
Author: SpudFarm
CpTn_lAw wrote:you know you can do a 60 fps photo capture and set the shutter speed to be very very high? this will (granted with a little chance) hopefully give very good full-res results.
(I did that two years ago and it worked)


I will probably try that, full resolution picture of a discarding sabot would be nice.

BTW, the chance of a shot today is pretty slim. Very humid weather and I have grinded the rust protection off the barrel. And the art shop had to order my clay from the producent.. On top of that they only had 10kg buckets :/