Short question topic

[jrrdw]

would a smooth bore 0.177 pellet gun be terribly inaccurate ?

When I was a kid I had a Daisy 880 that was great.......... up to 50 feet.

[jackssmirkingrevenge]

A question. The difference in temperature at which the air is heated in a hybrid, varies a lot or little depending on the stoichiometric ratio of fuel gas, butane or propane, be it 3.5% up to 8%? Does anyone know or have experimented with this?

If I remember well the experiments I had done with combustion cannons indicated that the ideal mix (ie not too rich or too lean) was the one that gave the most power.

would a smooth bore 0.177 pellet gun be terribly inaccurate ?

"Diablo" style pellets were originally designed to be used with smoothbore barrels so assuming you're not pushing them to transsonic velocities they should be fairly accurate. You want medium weight pellets around 7 grains that have the weight focused in the front. That being said a 0.177" rifled barrel should not be too hard to obtain, visit the "for sale" section of local forums and you should pick up a used one cheaply.

[hectmarr]

I am trying to vary the proportions, and I have obtained a lot more power and a lot less power depending on the case. 4.5 or 5% butane seems to give the best result.

[hectmarr]

I have seen that hydrogen peroxide of high concentration produces steam of hot water and under high pressure, passing through a silver grid catalyst. It is the fuel of the jetpack. It would be possible to push a bullet with this, I think. The peroxide is complicated to handle but I imagine that in small quantities it could be used.

[jackssmirkingrevenge]

I have seen that hydrogen peroxide of high concentration produces steam of hot water and under high pressure, passing through a silver grid catalyst. It is the fuel of the jetpack. It would be possible to push a bullet with this, I think. The peroxide is complicated to handle but I imagine that in small quantities it could be used.

Hydrogen peroxide with sodium permanganate is what provided the steam to drive the turbopump on the A-4/V-2 rocket:



https://v2rockethistory.com/gmedia/a4-v ... ifold-jpg/

[hectmarr]

I have seen that hydrogen peroxide of high concentration produces steam of hot water and under high pressure, passing through a silver grid catalyst. It is the fuel of the jetpack. It would be possible to push a bullet with this, I think. The peroxide is complicated to handle but I imagine that in small quantities it could be used.

Hydrogen peroxide with sodium permanganate is what provided the steam to drive the turbopump on the A-4/V-2 rocket:



https://v2rockethistory.com/gmedia/a4-v ... ifold-jpg/

Yes, I read that it was the hardest thing to achieve in the V-2 project. This is what injects ethyl alcohol into the combustion chamber, overcoming the internal pressure of this. Tremendous work of engineering for that time. In the case of the jetpack, they use an inert gas, high pressure nitrogen, to force the oxygenated water, to pass through the small reaction chamber that contains the catalyst. Complicated, no doubt, even if it does not seem so.
"The approximately pure peroxide is relatively stable, but in contact with a catalyst (for example, Silver), it decomposes into a mixture of superheated steam and oxygen in less than 1/10 millisecond increasing the resulting volume by 5,000 times, 2 H2O2 = 2 H2O + O2 The chemical reaction is exothermic with the consequent release of heat (approximately 2500 kJ / kg), forming in this case a vapor-gas mixture at about 740 ° C. "

[jackssmirkingrevenge]

I think it has potential, indeed we have another application of this from WWII where it is used to fire a "projectile" - the launch catapult for the V-1 flying bomb.



T-Stoff being high test peroxide and Z-Stoff was calcium permanganate/sodium permanganate mixed in water

We can see it explained in this German WWII training film for the device.

[hectmarr]

I had seen this video, excellent! I am sure that with the necessary tests and the necessary development it could be used to drive some type of ammunition.
What I see is that concentrated hydrogen peroxide is expensive, and on these sides, where I live, they sell it in large quantities. It is complicated to have this chemical to play a little. Apart from that, it is necessary a lot more technology and theoretical tools and knowledge than I have, to try it. It was just a "loud" thought. Maybe with a peroxide not so concentrated, that you can buy commonly, at 35%, and an alternative catalyst, and extra, you could make something basic, just to see and hear how it shoots. The question is to investigate if it has some power in these concentrations.

[farcticox1]

Saw one, actually 2 of those at Duxford IWM

[hectmarr]

Saw one, actually 2 of those at Duxford IWM

V1.JPG

IMG_2794.JPG

wow !! how lucky you are. It is an interesting piece of history. We, with the guys from the model airplane club, make a few, with and without valve on a clear scale. Engine interesting and quite simple to build.

[farcticox1]

You would have liked it there then

[hectmarr]

Without a doubt, I would like it. I actually have the planes as a hobby, which I build myself. Although it is out of topic I show you some. I have several. Excellent your photographs.

[jackssmirkingrevenge]

Saw one, actually 2 of those at Duxford IWM

Here's mine, it seems the piston caught my eye as did the fragmentation damage

The highlight of my visit however was coincidentally catching Sally B starting up for a test flight, literally brought tears to my eyes:

... and of course, her nemesis which remains a personal favorite:

Without a doubt, I would like it. I actually have the planes as a hobby, which I build myself. Although it is out of topic I show you some.

Nice work! You should make a thread in the off-topic section, that's what this part of the forum is for!

I also came to spudguns from model aircraft, but lost interest in them after I found out that making holes in things was much more satisfying! My first exhaust valve design even used balsawood plugs as endcaps, oh the folly of youth...

[hectmarr]

"making holes in things was much more satisfying!" :bounce: :bounce: :bounce:
YES !!! I love the holes !!! of the rocket nozzles, gas turbines, pulsorreactores and of the arms to combustion and of all type. I have always thought that all these little great passions are part of the taste for technology. I like ALL !
oh the holes in general, they are the most ...

[mrfoo]

Duxford's great.

When I worked for a certain airline, I won't give names but it was one of the ones who had a fleet of Concordes and wasn't french, we used to pop up to Duxford occasionally to "borrow" parts from the display Concorde. Hard to get the parts, you see, and some of them had a tendency to drop off the plane mid-atlantic at supersonic speeds.