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Jet Engine in a Model Rocket?

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RocketFeller

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There is another thread with a similar question that quickly turned into speculations about hundreds of G motors reaching space.

I was actually curious if you really could put a jet engine (the RC type) in the aft end of a rocket.

Would it have enough thrust?

Would it be within NAR/TRA regulations?

What kind of performance could you get?

I would think it could be cool if doable. You could fly it out of fuel and then recover electronically.
 

georgegassaway

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If you used nothing but a jet engine in a model that looks like a "rocket", then you have a model aircraft, not a model rocket.

If you augmented it to say use two rocket motors on the sides to get it going, then that would make it a model (or HPR) rocket depending on the engine(s) and mass. However, unless it was an electric powered "jet engine" (Electric Ducted Fan), then the fuel used by the jet engine would break the safety code rule that prohibits flammable payloads (no point in quibbling over whether fuel for the jet is a "payload", no legitimate RSO is going to allow a rocket model containing flammable liquid to launch).

But back to a pure jet powered "rocket shaped model aircraft", that would be OK as far as the model aircraft safety rules were followed. Now things like thrust to weight, totally depends on the jet engine thrust and how heavy (or light) the "rocket" was built. But it would be pretty unlikely to have a TWR of 2:1, in which case for a vertical liftoff it would not fly very long without weathercocking. So, for a project like that, it would really need to use some form of guidance, whether 100% manual R/C (very hard to do with a rocket even for an expert pilot), or some type of autopilot/flight controller that can help keep it vertical, or want to fly vertical. The actual physical steering in pitch/yaw would either need to be by some form of thrust vectoring (causing the engine itself to pivot, or having some heatproof "paddles" just behind it to deflect the exhaust), or aerodynamic controls such as pivoting nose fins. However, aerodynamic controls need some airspeed to be effective, so it would have issues of randomly veering off shortly after liftoff till it got up to a fast enough speed for the aerodynamic controls to be effective.

Hey, I actually found on youtube, a pulsejet powered "model rocket". But since it uses only the pulsejet, it's not a model rocket, it's a model aircraft.

[video=youtube;abr2Pt7SGi4]https://www.youtube.com/watch?v=abr2Pt7SGi4[/video]

This one is free-flight, no steering of any kind, so it starts to pitch over, but not too badly. So, the acceleration was pretty good, if that model had some form of guidance system and aerodynamic control surfaces on the lower fins, it could have been capable of flying itself to an great altitude before running out of fuel or the air getting too thin. Note that in this case, the pulsejet engine and its fuel tankage is pretty much the "rocket" body, with fins attached at the bottom. Actually this is one hell of a homemade pulsejet, it has three "nozzles" from about the middle point.

An earlier video, below, shows a lot of early static tests. Seems like it not only has those three middle nozzle-chambers (whatever they are), but also the classic pulsejet exhaust out of the bottom of the long tube.

He does have an R/C Transmitter, but that seems to be involved with the motor (throttle and perhaps shutdown), as well as deploying a parachute by R/C. So, technically it does use R/C, but not for steering/guidance.

[video=youtube;zV1snAMK-bY]https://www.youtube.com/watch?v=zV1snAMK-bY[/video]
 
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SaturnV

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Of course you can. Tomahawk is such an engine :) But I think it is more suitable for longer manageable flying rocket. Vertical flight Ordinary engine with solid fuel is more simple and convenient :)
 

TopRamen

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I have long wondered this ever since seeing the Jet engines they have for RC stuff nowadays.
Will be an interesting thread to watch, even though it is one of the threads where some will outright shun the idea because it is radical, and outside the realm of normal rocketry.

Regardless of which kind of waiver you would need or what it would classify as, don't tell me that this kind of tech could not some how, some way be used to get a rocket pretty darn high before stage one ignition:

[video=youtube;dTHWBSluUjU]https://www.youtube.com/watch?v=dTHWBSluUjU[/video]

[video=youtube;qQ9dSrrBN28]https://www.youtube.com/watch?v=qQ9dSrrBN28[/video]
 

TopRamen

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But let's also not forget, when these things crash, there would be a real mess of propellant and fuel.

The RC planes take off horizontally, but if you wanted to eliminate the mass and drag of the wings, yet get up to speed for continuous vertical thrust, you would need some form of track with a ramp.
 

SaturnV

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The advantages of this engine is that it does not bear the oxidant with him. Takes oxygen from the air. It can work relatively long time. The disadvantages are that a greater altitude where there is no oxygen, it can not work. Another disadvantage is that compared to engine of solid fuel is much more expensive and provides less thrust.
Possibly four such engine would be a good first stage for an amateur rocket :)
 

SaturnV

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As can be seen from the video engine does not have enough thrust and the rocket can not be stabilized. This can be achieved with a system for managing thrust or if the engines are more but it is costly and difficult to implement. Much easier and cheaper it is achieved with an engine using solid fuel.
But as first stage a great amateur rocket could be landed as the first stage of the Falcon 9. Only refilled with fuel and ready for a new flight :)But the cost of the turbines just do not think :)
 
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