SpudFiles

Are you at all worried about ddt in the 60x oxy/propane hybrid. In my opinion it would be almost impossible to avoid because of the mix and fact that you are using oxy instead of air. But for all I know the chamber is designed to take DDT's regularaly.

It would kind of suck if it DDTed, but it would provide us with some useful information. 20x oxy/propane isn't detonating in my ME20H-41, and I'd like to see where the limit is.

On the other hand, SB15 built a gun a while back powered by some REALLY awesome dust that would have detonated every time, and it only failed when the threads on the 8 1/2" bolts holding the backplate on got ripped out. Maybe, if the chamber can handle significantly more than the detonation pressure, detonation wouldn't be a significant concern, at least over the rather short operational lifetime of a ridiculously powerful and impractical hybrid.

DYI- What are you looking at with the previous mentioned 60X in terms of muzzle velocity and ft*lbs?

DYI wrote:The only product of oxy/hydrogen combustion is H₂O, which should increase the SOS in the post-combustion gases.

It certainly would. Also, if the SOS really does need boosting, you can supplement in helium to lower the gas density even more.
In theory, a mix of 1 part helium to 1 part H2/O2 mix would have a SOS high enough to reach a MV of over 1 mile a second without any problems with transonic effects.

(And having read that, you just know, don't you, that DYI is almost certainly considering trying that...)

My summer project is rather likely to drag on into an autumn and winter project as well, it's a long and complex task, and is also competing for funds with other hobbies.

As you probably know by now, I can't do big cannons - the ME of my project will only be 400 to 500 ft-lbs, so nothing really special there.
But that's not to say I can't cook up my own custom brand of mischief - two words: "Pancor Jackhammer". That's all I'm saying.

I'm working on a shell ejecting airsoft sniper rifle, just because shell ejecting guns have that "wow effect" and I want it for playing airsoft. I just finished making 50 shells for it out of brass tubing (took me almost an hour to de-burr them all) and tomorrow I will buy the rest of the parts to build it out of, so I should have it completed by the end of the weekend.

It certainly would. Also, if the SOS really does need boosting, you can supplement in helium to lower the gas density even more.
In theory, a mix of 1 part helium to 1 part H2/O2 mix would have a SOS high enough to reach a MV of over 1 mile a second without any problems with transonic effects.

I'm beginning to like the sound of this Helium would have the obvious benefit of providing a buffer against DDT, while not lowering the overall SOS in the chamber. On the other hand, I don't think it could be done on a scale that even approaches practicality, so I'm not going to drop everything to work on this.

Other-railgun and 3 stage coilgun.
Hopefully 5KJ for the railgun, 500-1kJ each stage for the coilgun.

BBMG hands down

Winter for me, but oh well.

1) Hybrid
2) High Pressure BB Singleshot
3) Big ass 4" piston valve cannon
4) Anything else

Those are projects i'll work a bit on each, I doubt i'll finish any more then one of them.

First things first, I am going to build a piston gun, especially now that I am inspired by MrCrowley's new piston gun. Afterwords, I want to try to develop JSR's Pre-Charged Piston idea. I'm fairly certain I can make it work. Drawings soon to come.

well this WINTER i will be working on a copper small bore, experimenting with the wonderful world of burst disks and getting around to posting my GB piston gun.

I am looking for something that is small, affordable, and can launch really far. Maybe try making some of those pvc rockets. I keep thinking about a hydrogen/oxygen cannon.

DYI wrote:I'm beginning to like the sound of this Helium would have the obvious benefit of providing a buffer against DDT, while not lowering the overall SOS in the chamber.

I knew you'd like the idea.
In fact, SOS after combustion in a mix like that would increase from around 1500 m/s (plain H2/O2) into the region of 2 km/s - and would have a surprisingly small effect on the peak pressure.

I spend a lot of time thinking about these things, although I will never be able to build most of them...
But if I can't build it, who am I to see the idea wasted by not at least suggesting it...

Enjoy it while you can guys, there will come a time when summer will be just like winter, only a little hotter

DYI is going to make a split around the ecuator (?) at some time!

i'll talk to you on MSN about these things


and i think i am going to make my pneumatic bolt action

After a few nights of not sleeping, I have decided to make a big hybrid