SpudFiles

Those numbers are looking pretty crazy! That's around adult-class pellet gun velocity, but you aren't shooting pellets. You're shooting .3 caliber lead balls, lol. Safe to say the air cane works well now.

Moonbogg wrote: ↑

Thu Mar 04, 2021 12:53 am

Those numbers are looking pretty crazy!

We're definitely in modern big bore airgun territory

It turns out there's a book that looks at these devices in detail, "Construction and Operation of the Air Gun Volume 2 - The Walking Stick Air Gun"

The performance listed for a similar muzzle-loading air cane is in the same ballpark as the results I got from the unmodified design:

More balanced valve development:



Version 2.1 with a stronger spring and a shoulder that bottoms out before the base of the valve hits the end of the balance chamber.

At 1100 psi, again using 45 grain 0.310" lead balls, the chrono read 789 fps for 62.2 ft lbs.

At 1500 psi, 860 fps / 73.9 ft lbs.

At 1600 psi, 163 fps / 2.7 ft lbs - obviously beyond what the hammer can reasonably open.

Not bad, but I was sure it could do better, so a coil was cut off the spring and further testing was carried out

At 1100 psi there was a slight improvement, up to 795 fps / 63.1 ft lbs.

At 1500 psi, WHOOOOOOOSHHHHH... no reading from the chrono as the chamber dump blew it three feet along the floor.

Subsequent investigation revealed that the spring had slipped over the valve shoulder, obviously the maximum diameter was a little too close.



This inspired the final balanced valve version 2.2 with as wide a diameter as could be made without compromising flow vis a vis the barrel diameter.

At 1100 psi it remained in the same ballpark at 786 fps / 61.7 ft lbs.

At 1600 psi now the hammer opened the valve comfortably so 4 shots were fired:

1) 869 fps / 75.4 ft lbs

2) 873 fps / 76.1 ft lbs

3) 860 fps / 73.9 ft lbs

4) 858 fps / 73.5 ft lbs

I thought I'd push my luck and took it to 1750 psi, another 4 shots were fired over the chrono:

1) 726 fps / 52.6 ft lbs

2) 883 fps / 77.9 ft lbs

3) 884 fps / 78.1 ft lbs

4) 878 fps / 77.0 ft lbs

The first low shot suggests that it's at the hammer's limit in this configuration.

More shots starting at 1700 psi showed similar results. I think I can happily call this "done", muzzle energy has been effectively doubled compared to the original and I'll wager it's some sort of record for an antique air cane. Also having fired about 25 shots with this last valve without failure, it looks like it's up to the job.

Here's one interesting result from the 786 fps shot at 1100 psi:



The lead ball entered the base of the aerosol can and ricocheted off the base at a 45 degree angle, still with enough energy to exit the can.

La investigación posterior reveló que el resorte se había deslizado sobre el hombro de la válvula, obviamente el diámetro máximo estaba demasiado cerca.

That's what I mean when I say that mechanics always teach me something, when I do tests, and I think that most of the time, first there is the fact and then the law ... On the other hand, their numbers are very good and the baton Victorian a modern and much improved weapon.

hectmarr wrote: ↑

Fri Mar 05, 2021 9:04 am

That's what I mean when I say that mechanics always teach me something, when I do tests, and I think that most of the time, first there is the fact and then the law

My style of engineering tends to be... "optimistic" ... so it usually takes a few tries before I do it properly, the way I ought to have done it in the first place

On the other hand, their numbers are very good and the baton Victorian a modern and much improved weapon.

I am half tempted to add a Picatinny rail mount for a laser sight, but no

Mi estilo de ingeniería tiende a ser ... "optimista" ... por lo que generalmente se necesitan algunos intentos antes de hacerlo correctamente, como debería haberlo hecho en primer lugar. :rollo:

In this way mechanics works, (and many other subjects of knowledge, if not all), when they are giving us a master class.
The laser sight would be great, but I think it would destroy that retro effect, when you look at the cane. As my dad used to say, new wine in old jars.

hectmarr wrote: ↑

Fri Mar 05, 2021 10:05 am

As my dad used to say, new wine in old jars.

A true poet, I like this expression

Damage video just to wrap things up, this thing is a lot of fun!

Yes, I am bumping this thread because I missed the final product after my annoying suggestions. Great work as always!

The damage video was fun to watch. This was a great project.

Thanks gents! Need to find the time to get back in the workshop, my current project is an old Remington 760 in for a full "tactical" conversion, KeyMod forearm, AR grip and stock, the works, and in exchange the owner promised a little deer hunting trip

jackssmirkingrevenge wrote: ↑

Thu Aug 19, 2021 11:32 am

KeyMod

Quad rails god rails.

mark.f wrote: ↑

Sat Aug 28, 2021 12:27 pm

Quad rails god rails.

That's what I ended up using, although it's now a tri-rail after I cut it to fit.

Here's what it used to look like:



... and here it is now, in all its shameful glory:

tech-ti-cool

what flash hider is that?

Anatine Duo wrote: ↑

Fri Nov 12, 2021 6:32 am

what flash hider is that?

Surefire knock-off made for airsoft, it's steel but I doubt it's going to last a long time to be honest.