Search found 18 matches

by MB
Tue Oct 17, 2006 4:32 am
Forum: Valved pulsejet forum
Topic: Fire in the hole!
Replies: 36
Views: 26464

re: Fire in the hole!

Two questions: Eric, Where can you buy Methanol? I presume because it's hazardous you can't just run down to Home Depot and pick it up like denatured alchohol or something. Jerry, Are the plans or specs or photos or something of the Aeromarine pulsejet on the web somewhere? Anything of dramatic impr...
by MB
Sun Oct 15, 2006 6:21 am
Forum: Valved pulsejet forum
Topic: Fire in the hole!
Replies: 36
Views: 26464

re: Fire in the hole!

Interesting concept. Hmm... Yes! We are definately getting ready for another firing next Saturday. We have the grid rebuilt, we've re-engineered the whole fuel nozzle thing, and have deployed a load cell to measure the thrust. I took a regular square-head plug (1/8" pipe fitting) and drilled a tiny ...
by MB
Sat Oct 14, 2006 5:52 pm
Forum: Valved pulsejet forum
Topic: Fire in the hole!
Replies: 36
Views: 26464

re: Fire in the hole!

Here's a short video clip of our first successful firing last weekend. This was our 5th attempt, so we were pretty excited that we finally got everything right. The engine died just as one of our team members was going to drop a rag into the jet stream to show its velocity. 28 seconds: not exactly a...
by MB
Mon Oct 09, 2006 2:58 am
Forum: Valved pulsejet forum
Topic: Fire in the hole!
Replies: 36
Views: 26464

re: Fire in the hole!

We've tried 6, 8, and 10 thousanths. These are 10's. The wooden test fixture is only temporary. We have designed a more generalized steel one that bolts onto a standard test stand we have access to, but it'll have to wait a few more weeks for funding (dang CR steel is expensive!). The rear-end of th...
by MB
Mon Oct 09, 2006 1:35 am
Forum: Valved pulsejet forum
Topic: Fire in the hole!
Replies: 36
Views: 26464

re: Fire in the hole!

Oh, these close-ups of the valves are precious.
by MB
Sun Oct 08, 2006 11:22 pm
Forum: Valved pulsejet forum
Topic: Fire in the hole!
Replies: 36
Views: 26464

re: Fire in the hole!

Oh, and I am still working on posting the video. It turns out the video capture card I have is one I used on MS/Win 95, and the vendor never updated the drivers to run on later versions of MS/Win -- bummer! So I gotta go out and get a new one afterall -- busted!.
by MB
Sun Oct 08, 2006 11:14 pm
Forum: Valved pulsejet forum
Topic: Fire in the hole!
Replies: 36
Views: 26464

re: Fire in the hole!

Lessons learned, and tasks planned: The fuel dispersal vanes were in fact splashing fuel directly on the valves, so the flame was occurring on the valve grid. Replace the nozzles with orifices that spray a cone pattern, and which will direct the flame away from the valves. We expect this will keep t...
by MB
Sun Oct 08, 2006 10:04 pm
Forum: Valved pulsejet forum
Topic: Fire in the hole!
Replies: 36
Views: 26464

re: Fire in the hole!

After about 30 seconds the engine just stopped. We figured, "Ok. We have some tuning work to do." But upon closer inspection we saw dramatic evidence of catastrophic failure. We tore it down, and discovered parts of the aluminum valve grid had melted -- in fact burned -- right through. Note that the...
by MB
Sun Oct 08, 2006 9:46 pm
Forum: Valved pulsejet forum
Topic: Fire in the hole!
Replies: 36
Views: 26464

re: Fire in the hole!

We played with it for a while with precisely the same results as before: we turned on the ignition sparker, gave it some air with a leaf blower; and all we got was some flame and a few puffs and booms. It occurred to me that when holding the blower into the inlet, there was quite a blast of air comi...
by MB
Sun Oct 08, 2006 9:24 pm
Forum: Valved pulsejet forum
Topic: Fire in the hole!
Replies: 36
Views: 26464

Fire in the hole!

Thanks to all who contributed in the thread titled, "How many things could be wrong?" That thread has wondered off to additional subjects, but I wanted to share our success. The alterations we made were that we bent the valve retainers closed a little, so the valves couldn't open quite so wide; and ...
by MB
Mon Oct 02, 2006 11:42 pm
Forum: Valved pulsejet forum
Topic: valveless "valved" pulsejet
Replies: 29
Views: 21015

re: valveless "valved" pulsejet

In all fairness to Bruce Simpson. He says on his web site that all the contents of the CD are now available on-line and is no longer distributing the CDs (any anyone who has one can get on-line). I registered for it with my credit card (it was charged by PayPal) last week, and I got a nice little no...
by MB
Sun Oct 01, 2006 10:25 pm
Forum: Valved pulsejet forum
Topic: Electric valve
Replies: 6
Views: 7777

re: Electric valve

Did I say that? What a dummy I am. Total length is the largest factor in the resonant frequency of a PJ, but the other factor is the Speed of Sound , which is the rate at which the shock wave travels. According to Wikipedia.com, "At sea level, at a temperature of 15 °C (59 °F) and under normal atm...
by MB
Sun Oct 01, 2006 6:53 pm
Forum: Valved pulsejet forum
Topic: How many things could be wrong?
Replies: 29
Views: 21353

re: How many things could be wrong?

Evildrome, I love your test-site! We do our test-firing out in the desert, where there is nothing to catch fire but dirt. You got a pretty good pop in your clip there. Ours was so big I felt the need to put my foot on it (the fixture, not the engine) to assure it wasn’t going anywhere. We are tryi...
by MB
Sun Oct 01, 2006 6:52 pm
Forum: Valved pulsejet forum
Topic: How many things could be wrong?
Replies: 29
Views: 21353

re: How many things could be wrong?

Eric, What, no girls? I'm out-a-here! Seriously. Our plumbing is configured (and sized) so we can experiment with a great variety of fuel flow. We wanted to be able to achieve and measure both ends of the performance curve varying as many parameters as possible. We presumed the intake duct was for p...
by MB
Sat Sep 30, 2006 8:13 pm
Forum: Valved pulsejet forum
Topic: How many things could be wrong?
Replies: 29
Views: 21353

re: How many things could be wrong?

Hmm... we thought that we needed more air, so we have been thinking about fabricating a more spacious valve grid. It didn't occur to us to try limiting the opening further. We'll give it a try. BTW, each of the 8 valves are 3 in. wide and about 2 1/5 in. high. I'm not sure of the jet orfice size, th...