Large Scale Central

Rocket launcher car idea

Modeling
#21

So Dan Gilchrist and I have been doing a little conversing about this car. The juices are flowing and I really don’t think it will be a difficult project. I have a depressed center flat car that I will probably never use, so I will use it as the base car for this rocket launcher. I will use a servo and control board to operate the launcher. I will employ some sort of remote switch to operate the servo and another to fire the igniter.

This will be a simple whimsical affair, not trying to even attempt anything close to prototypical. Just good throw it together fun. For the rocket I jumped on Fusion and designed some parts to be printed that will be joined with standard paper tubes. Rocket is small(ish), 20 cm long as designed, but since it uses standard paper tubes the length is customizable. . Will hold a 1/2A motor and be tumble recovery by ejecting the motor. Already ordered the rocket stuff. even if the car never sees the light of day I can still have fun with the rocket.

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This little Bluetooth controller would allow me to raise and lower as well as fire the rocket using my smart phone. It would be the switch that then runs the servo control board Dan posted.

#22

Deven,

As long as the flames are deflected away from anything plastic, it’ll work just fine! That short blast of intense heat will melt plastic and scorch wood if that it touches.

Eric

1 Like
#23

Already have a plan for a deflector if all goes as planned.

#24

After further review, and the clearing of some brain fog, I need to clarify earlier statements about recovery method:

Tumble Recovery: Does not eject engine, but shifts it’s position to alter the center of gravity. There is a metal clip built into the engine mount to retain the engine in the second position. There is a hole in the body tube below the nosecone to release excess pressure of the ejection charge. The shift in CG causes the rocket to tumble adding drag to reduce the descent speed.

Featherweight Recovery: Engine is ejected at apex (approximately) reducing the weight of the rocket so it can fall safely back to Earth. No holes in body tube, no special motor mount.

My confusion in the terminology is probably why the body tube hole I mentioned earlier was questioned.

#25

Okay that makes sense now Jon. I have never used the first method. But I have used the second method of ejecting the engine. And that is what I am aiming for for this little guy. But I am glad you said something sooner rather than later. As I have designed some printable sections and the upper fin section I designed a hole in it per your explanation. But I haven’t printed it yet so I will plug it.

#26

So since I can’t actually start my mik project I have been playing with the rocket launcher car. Printed the rocket parts I designed. They look good but I need the tubing and engines to arrive in the mail so I can test fit.

I also have an additional piece to go with the car that I have been working on. A “Mad Max” inspired diesel battle loco. I have a set of trucks and various parts of a switcher loco of some sorts that I acquired. Hoping to make a small armored loco to pull the rocket car.

Just looked at USA Trains and rhe donar loco is parts from a Alco S4. It was already chopped up and all I had was various pieces. But I shortened it another 3 inches from what it already had been shortened too. So it will be a pretty short loco.

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#27

Short enough to power with a single 3 axle truck?
Like a TP56

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#28

Not that short. I thought about doing something like that but since I had a pair of two axel trucks I shortened it enough that I could still but both trucks under it.

#29

Little more work on the battle loco

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Skinned the cab in armor.

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And added a textured walk way.

#30

Got a few details parts for the loco printed but not installed yet.

Rocket parts arrived and mated pretty well with my printed parts with just minimal sanding. Its a little heavier than I’d like but thats a matter of just making future ones with thinner walls. For this project I think it will launch just fine and I really don’t want a lot of height to make recovery easy.

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#31

We want video when its launched or Youtube Live will work too. Look forward to seeing it fly.

#32

Dan, just received the Vasile devices and I don’t understand what the wiring connections should be. The Vasile has the vcc terminal marked as negative, which is opposite of the Sparkfun. Also, does the input wire from the LM go to one side of the switch connection? Jim

#33

I actually haven’t had a chance to play with it. Every servo plug I’ve seen is Ground - Power - Signal and by looking at the video above it looks to be the same. MEC 31900-32149
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#34

Just got mine also. But haven’t started messing with it.

#35

So I have a whole bunch of electrical gizmos now. I think I have all of the gizmos I will need to make this work shy of a battery. I am not doing anything with it until the challenge is over but I can’t wait to play with all the gidgets and gadgets and see If I can get it all animated and running. If all goes well I have a key FOB that runs an electronic “switch” that has two outputs. One will run the actuator to raise and lower the rocket and one to light the igniter. I have a servo motor and control board. I also have a buck converter to drop the voltage tot he igniter down to say 9V from the 12V I am thinking of using overall.

#36

I have a feeling if the boys see this that i may have to reprioritize my post-MIK modeling!