Bomarc ramjet

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metiz
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Bomarc ramjet

Post by metiz » Tue Jul 01, 2008 1:13 pm

Courtesy of James, this is my first and probably last Ramjet. Darn these things are boring - better stick it behind my Talon 4 for some entertainment value. :P One thing tho can anyone confirm that this thing is actually operating as it should? (my leafblower is not exactly top of the range so keep that in mind)

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larry cottrill
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Re: Bomarc ramjet

Post by larry cottrill » Tue Jul 01, 2008 2:45 pm

metiz -

Nice. I figure if the roar of combustion drowns out the sound of the silly blower, you're probably actually developing some pressure. The flame seems a little unstable, but then I realize your leafblower was just hand-held (i.e. not really aimed straight in and locked down). One of the tough things about ramjets is that if you gate the airflow slanted a bit to one side, the diffuser efficiency sort of "rolls of the table" because you start getting shear & turbulence along one side. But, I think this basically looks like a pretty good run.

What I think somebody ought to do with their ramjet is make a nice motorjet out of it. Once the ramjet is perfected, it's a shoo-in -- all you need is one of the new high efficiency ducted fan units the R/C guys use and duct it in. Of course, a nice big one of those is going to be pretty expensive (batteries, too!). Another approach would be to use a piston model airplane engine with a leafblower impeller. You would make a custom housing (carved foam or balsa, reinforced with epoxy) so that you would get cooling air over your piston mill first, then duct it right into the ramjet. This sounds like a hassle, but any experienced modeler has probably done things much more complicated already.

I can never understand why motorjets are so utterly neglected. They have been used successfully, even in full-scale aircraft.

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metiz
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Re: Bomarc ramjet

Post by metiz » Wed Jul 02, 2008 2:09 pm

I atmit defeat. To save some dignity I wil post this hear before somebody else does - the engine is backwards. So there, I said it. I has been tested a 2nd time and it actually runs better if I blow in the intake instead of the tailpie! who would ever know...
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metiz
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Hehe entertainment value get

Post by metiz » Wed Jul 02, 2008 11:01 pm

Entertainment value get.

Strapped the Bomarc to my T4 engine, positioned at about 5 inches from the tailpipe. Injector used is a double slit 1/4 inch ss line located aprox. 2 inches from the flameholder. Man this should be good. Sorry for the crappy pic.
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Irvine.J
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Re: Bomarc ramjet

Post by Irvine.J » Thu Jul 03, 2008 2:43 am

Hahaha Metiz it was an honest mistake, don't feel too bad about running the engine backwards!

Man that looks shit-hot bud. I like the bomarc style as it has a really long diffuser, hopefully sorting those pressure pulses out before they get to the flameholder.
If you have problems with the flame holder keeping its flame in check, (it is very thin) and just stick your mig gun down there and weld on a little circle in the middle to take up some extra room, or even a very thing ring about 1/2 the diameter of the chamber.

The mounting looks sweet and I can't wait to see what you do here, looks rad as bud goodluck!
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metiz
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Re: Bomarc ramjet

Post by metiz » Thu Jul 03, 2008 4:15 pm

Is it possible to scale ramjets linear? (IE x2)
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