After Burner Use

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nitro
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After Burner Use

Post by nitro » Sun Nov 17, 2013 11:59 pm

Hi Everyone.I just had to put this subject in as yesterday I gave it a try and to some degree it worked.As we all know,Pulse Jets can suck back air after each bang produced.How much and how far back it goes is debatable but any air not used is air to fuel a afterburner.I put 5 off 6inch SS 1.6mm pipes all connected together strait up my German er90 Pulse Jets back end about 3inches.My thought on this was that it will mix with what air is coming back and burn in the tail cone like a rockets outlet and it worked.With the pulse jet running at full power static (12lbs) this instantly added at least 1.5lbs thrust for nothing.And a nice looking tail flame.I intend to develop this more and add it to my er90 for good.I want to add it to my Bailey fast jet to for Control Line one day & may just crack a new speed record.Anyone want to beat me to it to be the first.Why not.Cheers everyone

dynajetjerry
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Re: After Burner Use

Post by dynajetjerry » Sat Nov 30, 2013 4:21 pm

Nitro,
I'm sure there are many ways to add an "afterburner" to pulsejets; it is possible, however, your observed increases in thrust are due to the added mass of your extra fuel as much as because of the increased heat. Indeed, many pjs show similar improvements in thrust that result from injection of almost any liquid, including water!
In any case, Academy of Model Aeronautics rules for pj competition prohibit any kind of afterburners. What are allowed are ducts downstream of the exhaust that mix auxiliary air into the exhaust, so long as no extra fuel is involved. The exact size and position of such a duct is critical.
Jerry Wiles
Louder is always better.

nitro
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Re: After Burner Use

Post by nitro » Sun Dec 01, 2013 12:47 am

I did try water,& a 50/50 mix of methanol water but I noticed no change.Kero did.All a afterburner needs is air & in one report they claim 66% air to run the pulse jet came from the tail pipe.A instant jump & impressive change in sound & flame going from 12-13 to 14.5lbs static was fun testing anyway.It did use lots of fuel to do it.More lost if pumped into the center.I think putting it in through 6 pipes about 4 in from the end gets best result.OK.It may be not allowed to be used in flight.Reeds handled it fine.

nitro
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Re: After Burner Use

Post by nitro » Sat Dec 21, 2013 6:44 am

I did try a basic afterburner on the HobbyKing but go no result.I tried a basic fuel injector to but could not get it to run so gave up for now.The er90 is just so much more fun in every way.Starts instant,uses only 350mls of Kero type fuels a minute Static at 12.5lbs thrust.Throttles back to 5lbs smoothly & now the reeds are running cold & wet the hole time.A Very impressive engine.

nitro
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Re: After Burner Use

Post by nitro » Thu Dec 25, 2014 2:19 am

Afterburner not used now.ER90 getting 16lbs static thrust now and 17 with afterburner so not worth all the fuss.

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