Search found 60 matches

by randompkguy
Thu Apr 08, 2010 7:51 pm
Forum: Hybrid Cannons
Topic: Hydrotesting Vs. Shock Pressure
Replies: 16
Views: 6817

well this is good, obviously you don't assume deformation like you said, but i have some of this: http://www.mcmaster.com/#8980k54/=6ksz6v so i don't think i'll get too much deformation before it bursts. i'll have to read that other analysis too. EDIT: dHall, I'm using 80% of the yield strength, and...
by randompkguy
Wed Apr 07, 2010 11:45 pm
Forum: Hybrid Cannons
Topic: Hydrotesting Vs. Shock Pressure
Replies: 16
Views: 6817

yeah, I'm no longer worried. Also where are you getting CrMo from? DOM tubing is usually 1026 mild steel. No backpurge, as the end plugs were well machined to close tolerances, and about .75 inches thick, so the gas wouldn't help too much.

thanks for teh comment on mah welds. I love my miller :D
by randompkguy
Sat Apr 03, 2010 2:50 am
Forum: Hybrid Cannons
Topic: HEEELLLLP! (ignition troubles)
Replies: 16
Views: 6398

I was planning on getting the two from mcmaster (f'in love that place :D despite the high prices) but i just got impatient, so i used what i had (I'm sure you know what that is like)
by randompkguy
Fri Apr 02, 2010 6:12 pm
Forum: Pneumatic Cannons
Topic: Auto Loader 32mm
Replies: 36
Views: 11423

any pics of the inner workings of that schweet arse reg you built?
by randompkguy
Fri Apr 02, 2010 4:57 pm
Forum: Hybrid Cannons
Topic: HEEELLLLP! (ignition troubles)
Replies: 16
Views: 6398

It has numbers every 5 psi, major gradations every psi, and then minor gradations every half psi. Also I have been using my meter pipe for the latest tests, but I think the meter pipe method actually adds more inaccuracy to your measurement system because it necessitates a volume measurement, wherea...
by randompkguy
Thu Apr 01, 2010 11:01 pm
Forum: Hybrid Cannons
Topic: HEEELLLLP! (ignition troubles)
Replies: 16
Views: 6398

I'm sorry, I should have read your posts more thoroughly. Anyway, right now I'm using the 0-30 psi gauge that came with my lpg regulator. (I think it's probably the most accurate gauge I have now, but I plan to get some better ones) Thus I am limited to 2x mixes. I do have a spare welding cylinder o...
by randompkguy
Thu Apr 01, 2010 2:53 pm
Forum: Hybrid Cannons
Topic: HEEELLLLP! (ignition troubles)
Replies: 16
Views: 6398

Oh I don't skimp on hearing protection. I'm studying to be an audio engineer, so my ears are a huge asset. I'm actually worried that even with adequate protection the sonic boom from higher mixes will deal me some permanent damage. Also, " The smoke you've experienced in the chamber could be due to ...
by randompkguy
Sun Mar 28, 2010 10:04 pm
Forum: Hybrid Cannons
Topic: HEEELLLLP! (ignition troubles)
Replies: 16
Views: 6398

Well, finally got some consistency :D Five 2x shots in a row. Still only 6 layers, but I'll take what I can get. Gunna try some higher mixes when I can find a huge field far away from my city house :roll:
by randompkguy
Sun Mar 28, 2010 5:42 pm
Forum: Hybrid Cannons
Topic: HEEELLLLP! (ignition troubles)
Replies: 16
Views: 6398

Tried a couple of 2x shots and so far all have ignited, but I still can't use any more than 6 layers of foil. I'm going to try and tune the mix to see if I can get better combustion. Also there is still quite a bit of smoke left over in the chamber after firing, so that is another hint that my mix i...
by randompkguy
Sat Mar 27, 2010 7:17 pm
Forum: Hybrid Cannons
Topic: HEEELLLLP! (ignition troubles)
Replies: 16
Views: 6398

hm, ok i'll try that tomorrow and post results. I still haven't added the orifice. Also the times that i have been able to achieve combustion, there was always smoke in the chamber. Does this indicate a rich mix?
by randompkguy
Sat Mar 27, 2010 5:12 pm
Forum: Hybrid Cannons
Topic: HEEELLLLP! (ignition troubles)
Replies: 16
Views: 6398

Propane is heavier than air if I recall correctly....wont it separate from the mix by then?
by randompkguy
Sat Mar 27, 2010 3:54 pm
Forum: Hybrid Cannons
Topic: HEEELLLLP! (ignition troubles)
Replies: 16
Views: 6398

HEEELLLLP! (ignition troubles)

So I began work on my first hybrid a few months ago. It's designed for 20x mixes, made of DOM steel, and has been hydrotested to 3500 psi. Unfortunately, it doesn't fire half the time :-(. I've looked all around this forum, read the wiki, and read Hybrid Fueling 101. First I tried using the chamber ...
by randompkguy
Fri Mar 26, 2010 4:07 pm
Forum: Hybrid Cannons
Topic: HYBRID FUELING 101
Replies: 106
Views: 297104

Thanks for clearing that up. So I guess the method detailed on that other site gives you mass percent, which is useless in this case since we are measuring by volume. (stupid mistake on my part)
by randompkguy
Thu Mar 25, 2010 2:59 am
Forum: Hybrid Cannons
Topic: HYBRID FUELING 101
Replies: 106
Views: 297104

Sorry to correct the thread again :roll:, but there is one more thing I thought I should add: the proper ratio of air to propane is actually 15.6:1, or 93.9% air. In the first post it is listed as 95.8% air which is a bit lean (too much air). The ratio can be calculated using the method detailed on ...
by randompkguy
Wed Feb 10, 2010 10:25 pm
Forum: Hybrid Cannons
Topic: HYBRID FUELING 101
Replies: 106
Views: 297104

I was reading over this sticky as it is my first time building a hybrid, and I thought I'd like to point out what I think is missing information. Regarding the chamber pressure method of measuring mixes, you would first calculate the correct amount of propane for say a 10x mix: Vp = ((100/.958)-100)...