Playmobil rocket to flyable Playmobil rocket advice.

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Curlrup

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I'm new to scratch building model rockets. I am a model maker by trade, and would like to do a hybrid cardboard tube and 3d printed copy of this Playmobil rocket. I'm going to scale the main stage down to a BT 60 tube and go from there.
I need any and all advice to make this fly. I'm assuming I'm going to need more and larger fins to get that CP where it needs to be. Anything else I need to keep in mind?
 

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Funkworks

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The problem with plastic toys is that they're heavy, so you need bigger motors, but without certification, you're limited to A-G motors. It might be enough, but before making any investments, the first thing I'd do is weigh the rocket. Other people here can then advise on whether your plan is feasible.
 

Curlrup

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The problem with plastic toys is that they're heavy, so you need bigger motors, but without certification, you're limited to A-G motors. It might be enough, but before making any investments, the first thing I'd do is weigh the rocket. Other people here can then advise on whether your plan is feasible.
Apologies I was probably not clear. I don;t want to fly the rocket in the photo. I want to remake it from balsa, cardboard tube, and 3d printed parts using the toy as a reference. However, just looking at the toy I can see that CP will be too far forward from CG, So I'm assuming I need to add fins to the design I come up with, also some other considerations. So I was doing a sanity check with you guys, and seeing if there is anything else I need to consider. The goal is to have the new rocket based on the toy to run off a Super C or smaller motor.
 

Nytrunner

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You can take a page from the Estes mercury Atlas and make some display fin/stands that stick in the side tubes. That way the lines of the model aren't disrupted, but the stand/fins provide the stabilization
 

mbeels

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It'd be doable, I'd start with a simulation and put in your best estimates for the 3D printed parts. Then you'll get a good idea of how big the fins would need to be, and how heavy it ends up. You can make adjustments on the sim for weight and size to hit your target. As long as you're considering stability, velocity off the rod/rail, and recovery, those are the main things! The rest is details.
 

dhbarr

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That's lovely! I'd probably go with only one box-shaped clear fin affixed between the boosters.
 

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Curlrup

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Would love to hear a bit about this.
I have a bachelors degree in model making from Bemidji State University in Minnesota. I have worked for product development companies, service bureaus (model shops anyone can hire out), and now I work for the US Army. I make the one off prototype of whatever is being designed. So working prototype, photo realistic model, models of buildings, scale models of vehicles (Army stuff, it's cheaper and easier to ship a scale model to people to illustrate your point than people to a vehicle). I work in a lab full of 3D printers, and do everything from models to prototypes, to basic research and material research. In my consumer product days I made working prototypes, and photo models for catalogs. Some of my claims to fame that I did the first prototype of or photo model of are: The hands free towel dispenser that has the clear blue or smoked cover on it, the current line of lawn spreaders from Scotts, um....a lot of fishing reels since I used to work for Zebco.
 

BABAR

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This is outside the box, but I think easier than plastic fins. BTW, the base doesn't have to be round, it can be square or whatever. The base doubles as a display stand, and can be decorated to match the rocket.

 

neil_w

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Very cool! I didn't know there was a degree for that.
 

Curlrup

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It'd be doable, I'd start with a simulation and put in your best estimates for the 3D printed parts. Then you'll get a good idea of how big the fins would need to be, and how heavy it ends up. You can make adjustments on the sim for weight and size to hit your target. As long as you're considering stability, velocity off the rod/rail, and recovery, those are the main things! The rest is details.
Yeah I need to get my Rocksim software. I'm thinking it would be more accurate than old school CP and CG methods. Especially on this. I can draw it up no problem. I'm thinking nose cones, and mock thruster bell housings 3D printed...maybe some side details. The rest balsa and tube stock.
 

BABAR

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Not exactly the same thing, but shows you can use a square base. The Tank Killer was rock solid stable. Straight as an arrow, no rotation
 
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