Air Turbo Rocket ATR

[airrocket]

Sounds like what most of you need is an Air Turbo Rocket ATR. With ATR you get the best of both turbines and ramjets. ATR uses a gas generator burning a rich fuel mixture liquid or solid fueled to drive a turbine for low speed acceleration until the ramjet sequence kicks in. The fuel rich gas then is injected into the combustion chamber and ignited to produce thrust. I'm currently working on a micro air-augmented rocket. And I'm searching for information on building micro turbines for Rc jets. The turbine will be the basis for my design. Anyone know of micro turbine plans? :idea:

[skyfrog]

What thrust figure do you need for your ATR ?

Here's set of plans for KJ66. Around 18lbs of thrust you can get from this turbojet engine.

http://www.pulse-jets.com/phpbb2/viewto ... light=kj66

[Zippiot]

http://www.gtba.co.uk/engine_designs/index.htm

and get this book (i gotta order my own too, amazon only has 1 left, but i cant get it yet, my parents have the amazon account and they wont be back for a few days)

http://www.amazon.com/gp/product/095105 ... e&n=283155

and this one is the follow-up

http://www.amazon.com/gp/product/095105 ... e&n=283155


but there is an issue with your ramjet. if it really was that simple it would be commonplace...

ramjets are very different from air breathing rockets, and rockets that can sustain ramjet operation are super difficult to design. air breathing rockets actually separate oxygen from the air for rocket combustion. hybrid rockets that can sustain ramjet operation have a fundemental flaw, ramjets, altough absent of moving parts, have many curves that are precisely made to shape the flow speed and pressure of incoming air. a rocket engine is usually just a smoothe pipe, doesnt have the needed curves to make good use of ramjet operation...

but ramjet/turbine hybrids do work, and work quite well as we saw in the sr-71 blackbird. also rocket assisted ramjets are commonplace in missles of all types. but the ramjet is usually separate from the rocket...

ramjets can work around 200 mph, model aircraft are now approaching 300 mph so it is possible to run an rc ramjet.

if you want to make a really simple lightweight and working ramjet, take an old empty aerosol can. gut it. cement in a flameholder (it will be damn near impossible to weld it in, and glue wont hold from the heat). drill a hole in the side for the fuel, and weld on a nozzle. if welding wont work you can make one out of cement on paper, it take s alot of practise but it does work. kitty litter is another alternative.
i have gotten about 3 pounds of force out of a very crude aerosol can ramjet, which is actually a lot more than expected. i didnt think it would work at all but i guess its easier than i thought. now the flat interior of the aerosol can goes directly against what i said eariler, well not quite...
the intake and exhaust need to be ver precisely engineered. usually the intake should be between 1/3 and 7/9 the exhaust. it all depends on the design of the flameholder and the rest of it...

the flameholder is second most important after the intake/exhaust ratios. the flameholder slows down incoming air to combustion speed, which as i understand is a few meters per second. i have seen a flameholder shoot out the back of one of my rams, and instantly the jet blew out... a stainless strainer works, but there are so many better designs if you are willing to put in some machining time.


build a working turbine, and design a ramjet around it, similar to the sr-71 design.

[Zippiot]

oh btw, solid fueled ramjets=freaking awsome!!!

i abused the hell out of my maggie muggs until one day, i thought i would mix epoxy motor oil and gasoline...

IT WORKED!!!

anything solid that readily burns will work, roofing tar works fine, pvc pipe, pvc pipe glue, most types of glue, many things.

[airrocket]

The KJ-66 at 18 Ibs thrust is in the ball park of what I need. Thanks for the link to the plans and other suggestions from others as well. I think I may be able to use turbine parts of the KJ-66. The air augmented rocket uses the turbine to compress oxygen for the augmented rocket cycle. This reduces the volume of LOX or NOX that the rocket (Mass Fraction) must carry. Once speed exceeds mach 4 the AAR shuts off the inlet to the turbine and operates as a rocket on internal stored oxidzer. The AAR is hybrid turbine/rocket, similar to a ATR in some ways. Flight profile is straight up to mach 5 for only a few seconds of powered flight in rocket mode. Then coast to apogee, pop a small kevlar chute to 15K' then Rc microflight gliding recovery of sub-scale lifting body UAV.

[Zippiot]

sweet