Search found 26179 matches

by jackssmirkingrevenge
Thu Nov 16, 2023 11:19 am
Forum: Hybrid Cannons
Topic: Compression Ignition Hybrid Testbed
Replies: 6
Views: 5074

Re: Compression Ignition Hybrid Testbed

Excellent post!!! You can see all the experimental work with a single glance!!! Thank -you- for this great collaboration :) There is room to investigate different fuels but one thing to take into account when making comparisons is the relative size of the cylinder that is a critical parameter in th...
by jackssmirkingrevenge
Sun Nov 12, 2023 10:23 am
Forum: Hybrid Cannons
Topic: Compression Ignition Hybrid Testbed
Replies: 6
Views: 5074

Compression Ignition Hybrid Testbed

As mentioned earlier what was presented as the Mini Hybrid II is actually a component of a wider project that I will attempt to detail here. I would first of all like to thank hectmarr with whom this project was a collaboration and without whose input would not have happened. Here is an animation sh...
by jackssmirkingrevenge
Sat Nov 11, 2023 8:40 am
Forum: BB, Airsoft, and Pellet Guns
Topic: Yet another help request
Replies: 1
Views: 1408

Re: Yet another help request

Welcome to the forum! That's a lot of questions and indeed if you're completely new to the subject the amount of information here can be overwhelming. a pneumatic semi-automatic BB gun as a self-defense weapon, purely for educational purposes It's worth noting that this forum frowns upon any discuss...
by jackssmirkingrevenge
Sat Nov 11, 2023 8:15 am
Forum: Pneumatic Cannons
Topic: Coke can to 150 meters?
Replies: 4
Views: 2129

Re: Coke can to 150 meters?

No worries, that's what this forum is for :) have you tried right-clicking on the GGDT icon and selecting "Run as Administrator"? That usually solves the issue.
by jackssmirkingrevenge
Sat Nov 11, 2023 8:09 am
Forum: Hybrid Cannons
Topic: Mini Hybrid II
Replies: 11
Views: 28285

Re: Mini Hybrid II

mark.f wrote:
Sat Nov 11, 2023 4:10 am
Does it have to do with cartridges?
Thanks! It's sort-of related with cartridges in that I mated it with the cartridge from the fl(air) gun to make a dual chamber testbed, lots of data generated with that one so it will take some time to compile.
by jackssmirkingrevenge
Sat Nov 11, 2023 12:53 am
Forum: Hybrid Cannons
Topic: Hybrid disk burst pressure effect on performance
Replies: 20
Views: 29899

Hybrid disk burst pressure effect on performance

One of the experiments I've done with this project to to see how burst disk strength influences performance. Intuitively one would tend to think that the stronger the disk, the higher the pressure it will burst at and therefore the better the performance will be; this might be true of a pneumatic bu...
by jackssmirkingrevenge
Thu Nov 09, 2023 2:48 pm
Forum: Combustion Cannons
Topic: Dose UKARA cover spud guns in the uk
Replies: 6
Views: 5598

Re: Dose UKARA cover spud guns in the uk

mrfoo wrote:
Thu Nov 09, 2023 1:08 pm
For example, anything that could be considered a "blow gun" is a restricted weapon and possession of one could land you up in jail. Think "pea shooter".
What a complete farce. This event seems to be going strong though, perhaps it's not so bad in practice.
by jackssmirkingrevenge
Thu Nov 09, 2023 12:26 pm
Forum: Hybrid Cannons
Topic: Mini Hybrid II
Replies: 11
Views: 28285

Mini Hybrid II

It's been over a decade since I first made this project and almost as long since I dabbled in hybrids so here is a recent project along the same lines: 20231108_233649.jpg Nothing particularly special about the design, chamber volume is around 34cc and it's currently fitted with a 490mm long 6mm bar...
by jackssmirkingrevenge
Thu Nov 09, 2023 10:49 am
Forum: Pneumatic Cannons
Topic: fl(air) gun - mechanically locked pneumatic cartridge for a 26.5mm flare gun
Replies: 13
Views: 31419

Re: fl(air) gun - mechanically locked pneumatic cartridge for a 26.5mm flare gun

Mate, that’s cool stuff, I miss the days of air gun fabrication 10-15years ago. The online landscape has changed, social media has effectively killed off this kind of forum for many such hobbies, and the majority of the cadre that was keeping Spudfiles alive has grown up or moved on and there haven...
by jackssmirkingrevenge
Thu Nov 09, 2023 10:33 am
Forum: Pneumatic Cannons
Topic: PVC and ABS pipe for the barrel
Replies: 5
Views: 3841

Re: PVC and ABS pipe for the barrel

cokecancannon.jpg Here is a quick GGDT model of a pneumatic launcher with a 0.25 C:B ratio and a relatively lightweight 25 gram projectile in a 1 inch diameter barrel. The model suggests that starting with 300 psi and using a fast valve, the pressure in the barrel spikes at 250 psi, the blue line o...
by jackssmirkingrevenge
Thu Nov 09, 2023 10:08 am
Forum: Pneumatic Cannons
Topic: Coke can to 150 meters?
Replies: 4
Views: 2129

Re: Coke can to 150 meters?

double post please delete
by jackssmirkingrevenge
Thu Nov 09, 2023 9:57 am
Forum: Pneumatic Cannons
Topic: Coke can to 150 meters?
Replies: 4
Views: 2129

Re: Coke can to 150 meters?

Wecome to the forum! 1) Based on your experience, can a pneumatic like I describe reasonably do this? I am having a really hard time guessing how the can will fly, so I'm worried it will produce a lot of drag and I won't be able to make the range target I have. I suggest you download Gas Gun Design ...
by jackssmirkingrevenge
Thu Nov 09, 2023 9:45 am
Forum: Combustion Cannons
Topic: Ideal C:B ratio?
Replies: 3
Views: 3415

Re: Ideal C:B ratio?

mark.f wrote:
Fri Oct 20, 2023 4:19 pm
You could try using HGDT to model your cannon instead.
Seconded, and as the creator of said program has expounded above, the real answer is "it depends" and HGDT goes a long way in giving a very good idea of how those variables will affect performance and efficiency.
by jackssmirkingrevenge
Thu Nov 09, 2023 9:41 am
Forum: Pneumatic Cannons
Topic: High pressure 50cal rifle
Replies: 6
Views: 5119

Re: High pressure 50cal rifle

The sealing faces in the picture are made of brass, which worked great for about 30 shots, but then became problematic (likely due to dust/contaminants). I rebuild the sealing faces out of Delrin, which has worked consistently. I remember wondering about this in your first thread and to be honest I...
by jackssmirkingrevenge
Thu Nov 09, 2023 9:31 am
Forum: Combustion Cannons
Topic: Dose UKARA cover spud guns in the uk
Replies: 6
Views: 5598

Re: Dose UKARA cover spud guns in the uk

This thread is over a decade old but probably still relevant, UK laws were fairly restrictive then and I doubt they have gotten better in the meantime.