Schedule 40 6" Test

[Bent]

Hey guys, I don't know what file format you guys are using for your videos! but I can't view them.
I can't find a good camera in town that will suit my needs. I was wondering if a web cam would give a good enough image so you guys could see the "FREAKING EXPLOSIONS" coming off of this pulse cannon.
I don't own a web cam and have steered clear of them untill now but there are some available in town.
Since I modifyed this test pipe...I haven't had it self sustaining but don't care about that now 'cause this thing detonates way better than my golf ball cannon!...now picture this
the pulse cannon is set up in my garage pointing out the middle door, I hook up the glow plug to the battery charger and then turn on the propane 1/4 throttle on the ball valve...wait 5 seconds and the windows shake in the garage , A sledge hammer percusson hits me i the chest and my ears ring before I register the sound that just hit me.
The pulse cannon just fired 5 times in about 3 seconds and with each blast...there was an air shockwave that hit the ground about 30 feet away from the garage kicking up a dust ball, the first was in the middle the second hit to the left and the last hit to the right...all within a 7' diameter. I don't think all 5 made contact with the ground but I can't be sure...Cool
I can't get it to repeat a 5 blast yet...but it will fire 2 times quite often and sometimes 3
After each run, I stick the air line to the intake and blow out the flame,
The propane draws room air in through the intake as it enters the combustion chamber and the glow plug won't ignite the mixture untill the lower explosive limit (LEL)is met. I think I will tweak the intake a bit
to see if that helps duplicate that awesome blast

[Mike Everman]

my webcam works great when I remember to focus it. I have a few Logitec's

[CG]

CNN just reported a magnitude 5 Earthquake somewhere in Northern Alberta , with aftershocks coming a few seconds apart...

[Bent]

Hey fellow testers, I apologize for the poor video quality...but I'm still just using my cell phone. here is my tuned test engine running with only 1 propane bottle feeding 1 bank. Even though I have a tee'ed fuel line set up, all the fuel is being syphoned to 1 bank or the other. Not both equally, so I will need to modify the supply.
This puppy roars now
The best way to describe the sound of this thing is " one of the low notes on Close encounters of the 3rd kind"

I had to zip the video so the site would accept it. if you don't have the viewer... http://www.apple.com/quicktime/download[url]

[Rossco]

mmm, i doubt that it is your fuel t piece, maybe it is a fueling problem although its more likely to be placement and induction than just the lines supplying it.
This seems to be the normal for such a combuster.
I had one going at one stage like this and i did a lot of tail testing trying to force it into out of phase operation.
Hell, even in phase, it would have been ok. As soon as it started to thump together, one half would cut out. It was drawing air, and plenty of fuel, it just refused to go bang at the right time.
Keep on going, your doing some interesting stuff here.

Just a comment here, but i would suggest that in this configuration it is only ever going to operate as a twin combuster, rather than any type of blast compression.
What would be the ideal blast compression is using the pressure gain to PRE compress the new charge in the second chamber. Then you have something! Getting it to self sustain this way is hard to say the least!
To do this, your combustion zones need to be a long way apart.

Rossco

[Irvine.J]

Man, thats a monster. I think its great you got her running Bent! Amazing.
I would really like to see what happens if you add an extra fuel line so your feeding both CC's with its own propane tank... and then LIQUID!!! (Tip tanks upside down when you have it running at lowest throttle. I think when its running full power the cameraman wont be able to stand behind it without earning the nickname "Stubs".

[Vermin]

Is it possible that this is reminisant of this? or somewhat similar? although bigger.....Just asking.

[Vermin]

or this? Just asking?

[Bent]

Nice job Vermin Same principle but like I said earlier...I'm just passing time and trying to learn a little while waiting for bruno. I realize most of you folks are light years ahead of me on design (both theory and practical) but the only way I can hope to catch up a bit is by tinkering...I don't want to be totally clueless when build time comes.
I am missing a fitting to get 2 bottles hooked up so I added a ball valve to isolate one bank for now and added thrust augmentors. Check out how easy it is to start without air.

[Irvine.J]

Heya Bent.
GET THAT FITTING!!! DO IT DO IT DO IT!!! Hehehe. Also, try to spark both CC's at exactly the same time when ready.I'd suggest run your 2 propane lines from the bottles to a 3 way connector. Off the free plug/thread (going to your engine), attach a nice big 1/4 or full turn tap. Immediately off that, another 3 way split, so that as you turn up the valve, the 2 CC's get the same amount of gas with plenty of flow. Also, you can have both bottles turned to max fuel, and simply throttle on the tap/needle valve. Heres a quick easy setup and its all 1/4 inch to go straight from Primus (orange) gas lines, then your standard 1/4 airhose fittings you can braze 1/4 inch copper lines directly into, and run them to the CC. (With double D's of coarse )

Heya Vermin.
Reminiscent yes, similar I'd have to say no. Your engine is also very nice and is adopting a similar principle, though is a very different design. Thats where the similarities end I would imagine. The Blast Compression chambers Bruno talked about many years ago, and he kindly provided us all with a huge amount of information to do with what we will (Thanks Bruno!)
To me this engine looks strikingly different Vern, its just another engine that employs a principle which you thought was worth a try and sure enough you succeeded in quite a nice engine!

Bent again:
I'm gonna speculate here...
I would suggest that because the combustion chambers are separated by that U-bend, that the blast compression event might actually be running at some time out of phase with the wave event down the tailpipe. If it just so happened you got the numbers right, you just mind find your compression reflected wave, is reaching the CC in time with the return wave from the tailpipe, hence increasing your chamber pressure much higher, which would be a VERY interesting and quite possibly more powerful engine than I think your expecting. Your intake setup is very interesting too, I'm actually very enthusiastic about it. The U bend is a short distance and I'd say off the top of my head that the U bend might be running at twice the frequency of the tailpipe though, its hard to say, FUEL IT UP and get lots of good video! Food for thought anyway.

[pgup]

Is it possible that this is reminisant of this? or somewhat similar? although bigger.....Just asking.

hey Vern what was the total thrust of that engine?

[Irvine.J]

I forgot to mention that with that duel fuel line setup you can have the engine running like you normally do on one of the tanks and 1 tank upside down ready to crack straight on with the liquid propane.

[Bent]

I had one going at one stage like this and i did a lot of tail testing trying to force it into out of phase operation.
Hell, even in phase, it would have been ok. As soon as it started to thump together, one half would cut out. It was drawing air, and plenty of fuel, it just refused to go bang at the right time.
Keep on going, your doing some interesting stuff here.
Rossco

Hey Rossco, I got it running on both banks simutainiously! It roars now
Irvine, I'm just a newbie at this but... I think that adding the extra propane bottle for its volume of fuel didn't help as much as giving the resonating pulses feeding back through the fuel line another chamber to dissipate into. What do you think?
It certainly doubled the thrust comming out of the exaust on both banks and there is now a pure blue focused flame out of both intakes and exausts. I'm just glad I moved it outside prior to firing it up for the 2 bottle test because it was glowing yellow in seconds

[Irvine.J]

In an engine like that it would be completely negligible. With 2 bottles simultaneously feeding fuel into each CC it should be just fine, I think getting them to fire at the exact same time would be the most difficult thing. If you want to give yourself the best chance perhaps you need the same sort of thing for your air compressor, so that you have not only the same amount of fuel, but air too when you spark both chambers. You'd have to double your psi to make sure both CC's get a big slug out of air tubes. (100psi for both chambers should do it no problem. 50 each)
Sounds like you got thumping now, keep experimenting and keep us up to date.

If its glowing yellow in seconds you are definitely on the right track

[Bent]

Hello James, the engine fires up without air and with both 20 lb propane tanks turned on, I just needed to "feather" the ball valves a bit to get both chambers firing. I should note that with both chambers firing...I noticed a significant increase in thrust and a dramatic decrease in propane consumption.
I'm done with this test motor as it is! I have recorded all dimensions and internal baffle placements and will find a place to either store it or buck it up for some future project
Thanks to all who've shown an interest, my rant is done!
Bruno... I'm ready when you are