Taking the Rocket Plane to the Next Level


Sunny Day Park Flyer
I like planes. I like rockets/space. I have model rocket engines from a few years ago. I have a Cargo plane with a large enough cargo bay. LINK:http://forum.flitetest.com/showthread.php?19823-Twin-Boom-Twin-Engine-FPV-Cargo-Plane-Build-Thread
So, being the Mad Scratch Builder I am, I decided to mash them together to build something awesome.

I first needed to mount the rocket engine in my plane, which presented it's own challenge.

Technical Bit:
Most model rocket engines have 3 "stages" of fuel: Propellant, Delay, and Ejection. The Ejection charge is basically a little explosion which, on rockets, blasts the parachute out the top end so it doesn't lawn dart. But this is no model rocket. So, I anticipated there will be a little explosion and I decided that the best way to not have the plane explode is to shoot the engine out the back. NOTE: If you want to try this sort of stuff, you can get engines without an ejection charge. I'm lazy and broke, so I made my own problem.​

I have a PVC pipe with an end sealed, the engine itself, and an O-ring holding the engine in place (which worked better than expected) The ejection charge would simply knock the engine out the back.

I was trying for about an hour yesterday, but earlier, I got it to work.

Let me know if you have any concerns about me putting this on a plane (be honest)


Senior Member
If you eject the motor, it may land someplace flammable and still be hot enough to start a fire. It's better to keep it in the plane. You can drill a small hole in the side of your pipe and arrange things so that the ejection charge vents out the bottom of the plane. Or use the charge like it's used in rockets to activate something - release swept-back wings or something to that effect.


Sunny Day Park Flyer
I've considered that possibility of a grass fire. In addition to an extinguisher; I'd only do this after a rainstorm, or in the winter with snow everywhere.

As for the ejection charge, I like the idea for it to blow out the bottom!
what I was thinking is to have concentric pipes with holes for the ejection charge blast to escape out the larger pipe
Either way, I just want to see if it's POSSIBLE for a model rocket engine to be launched from an airplane with motors.

One of the reasons I'm doing this is because nobody has thought to have both a motor, AND a rocket (also, the EDF afterburner concept seems a bit advanced for me)

Also, is the video fixed?
My brother and i used to build rockets all the time as kids. I have thought about doing this, but want to get my flying down a bit better before I start strapping external rocket boosters to my planes.;) it will happen some day though.

I also had the same idea as you regarding the chute blast ejecting the engine. Great minds think alike, hehe

the main issue i had is that mounting the rocket engines on the back, then ejecting them is going to play havock with the CG


Senior Member
Wow! Just watched the video. How much thrust is that generating? Are you using potassium nitrate for the primary fuel source?
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Sunny Day Park Flyer
I don't know what these engines use as fuel. That engine was an Estes A8-3. I might use a B6-4 for the flight.
The total weight for the a standard engine is around 10g, not enough to mess with the CG.

What I'm more worried about is the thrust-angle. These engines make up to 3lbs of thrust (for.2 seconds)
So I have to be careful about the angle and position.
I'll probably put it 1/3 from the bottom of the cargo bay so it's mounted slightly above in-line with the battery.

I have to make the mount next, but with school, it might be a while until I can fly it.


Senior Member
I thought you had made the engine!!! It looked similar to this project:

1/3 from the bottom sounds good to me. I have played around with model rockets myself, and they are a blast (pun intended:p)


Sunny Day Park Flyer
Mount Finished!

Sorry in advance, this took longer than expected due to major educational setbacks (homework)

I've figured out how to mount the pipe/engine assembly in the plane!
As you can see:
WP_20150912_21_23_02_Pro 1.jpg
I just cut some holes in a hose clamp, and attached pieces of wood with screws.

I think it looks pretty nice. Now I've got to get a brushed ESC to ignite it
WP_20150914_13_39_26_Pro 1.jpg
Looks promising. the reason I had mentioned CG is that i had thought about putting one (maybe two) on the back of a Viggen. i guess in the load bay of your cargo plane it wont make much difference
I have just taken delivery of some C2 rocket motors and have started building a new Viggen to put them in. apparently they produce 2Kg of thrust. coupled with the 12 blade 3500KV edf im guessing its gonna go pretty fast :O i have a turnigy reciever operated switch which im using as a relay for a seperate 9V circuit to trigger the igniter. hopefully it wont explode or fling itself at the ground at 150mph :black_eyed: