Coating To Add Strenth

[RocketNut 1]

Does any one know what coating I can use to to strengthen a model so it will not beak at the outer shell layers? The project I am working has to survive and not break when dropped from high heights. So I want to coat the model with a hard coating to ensure it does not break alone the shells layers.

Thanks

Rocket Nut

[yellowshark 153]

Well XTC-3D certainly cures to a very hard finish. Its job though is to provide a smooth finish so I have no idea just how much abuse it would take. I will see if I can drop a piece from a 1st floor window tomorrow 8)

[RocketNut 1]

Thanks yellowshark

I am working a model rocket booster for a multi stage bird. If the math is correct it could be over 1500FT when it drops off. It should tumble on the way down, reducing the force of impact.

May be adding carbon fiber or fiber glass strands to the coating will possibly increase survivable.

Edited February 10, 2017 by Guest

[avogra 68]

I would rather look out for the best printing material. Can't imagine that any coating helps against more than scratches in surface.

My suggestion would be to print in Nylon, which is not super stiff, so it can dampen the impact.

I think Carbon reinforced material breaks even easier, becausr it is stiffer.

[SyntaxTerror 344]

Agreed. I'd go for something that bends a little rather than something stiff. Stiffness gives you nothing but a tendency to break. Trees in the wind and all that. Which materials have you tried this with?

[geert_2 556]

My first idea too was to try nylon. But maybe PET or PETG would have a better layer bonding, and they are still relatively flexible? You don't easily break a PET bottle when dropping it. And PET is easier to print and has a better bed adhesion.

I think it will also depend a lot on the shape, whether that is able to absorb any shocks, and to distribute the load, without high local concentrations of forces.

Try smashing the part into a concrete wall to test it.

Would be interesting if you could post a few photos of the results.

[RocketNut 1]

You can find all tech info (along with pics) at MAMMOTH Stage 1 Booster V2 As you can see this a larger bird.

I using Taulman Nylon Bridge 3D Printing Filament. I have not used PET or PET. What are advantage and differences of these from filaments?

I like that XTC-3D smoothies the surface of the print, making more the booster more aerodynamic reducing drag.

I am still a newbe to 3D printing. I really a appreciate you all shearing your wisdom.

Rocket Nut

Edited February 14, 2017 by Guest

[krys 206]

Hi there,

For me, PETG has a bit of flex, like ABS, but not huge. Nylon (i.e. Bridge) is damn near indestructible, but it can deform if bent too much. Another option would be Polycarbonate. It is both stiff and strong. But it is also hard to print. That said, I have not tried the newer PC formulations that are easier to print. So it might be an option to explore if you want both stiff and strong.

Anyway, hope this helps.

[DeathMachine 23]

I think you are asking too much from a paint coating. I would choose a different material to make your print from.

[geert_2 556]

Just a few things that came to my mind:

- What about the heat generated? Is that contained in the engines, or does it spread out to the 3d-printed housing? If any heat is spread out, obviously PLA would be a bad choise. Maybe all plastics. Especially on a vertical take-off from the ground there is a possibility that the wings would melt and catch fire.

- What about flutter of the wings? I have heard this is a very common problem in airplanes, even at relatively low speeds (a few 100 kt)? It already is a problem when driving with open windows in a car at 100km/h. When using flexible materials, this could be a problem too, unless you would use very thick wings with internal stiffening structures. But that would greatly increase the frontal area and thus drag.

- How do you plan to stear the rocket? Does it have active controls and do the vanes move like in military missiles? If not, the tiniest imbalance in the engines or wings could bring it out of course.

Concerning survivability, I think not much is going to survive a drop from 1500 feet. Unless you attach a sort of parachute or balloon that automatically deploys. Or speed brakes that fold out, activated by springs, or so. But that adds complexity and weight. Most model airplanes are destroyed on a crash even at low speeds and heights.

Personally, I think I would go for thin aluminum plates to make the wings. Or if they were steerable, maybe use a sort of "gratings" instead of wings, like in modern military missiles. I am not sure why they use these? Maybe better control? More compact? Easier to fold and transport? Less drag? But you see it more and more.

Anyway, I think this is an interesting experiment. I am curious about the final results.

[RocketNut 1]

geet_2:

Your thinking of NASA type of rockets. This booster is make for model rocketry. Meaning most of the things you mentioned, do not apply with is project. Most model rockets are made with paper tubes, balsa wood fins and possible some plastic parts (nose cone, fins, payload compartments, ETC) . For this project I am using a 3D printed booster for a multi stage bird.

Edited February 20, 2017 by Guest