L1 using cardboard airframe and 3-D prints?

[Vonkrumm]

Hi Guys,
Just wondering if anyone has done a similar scratch build rocket, using a H or I motor....



Airframe: Cardboard mailer tube, reinforced using fiberglass and epoxy.
Nose cone: 3-D Print PLA
Fin can: 3-D Print PLA
Motor: 38mm DMS - Ejection delay

I will check loads once all put together... but it looks like a lot of other people have done something similar.
As long as I pick the thrust curve so the rocket pulls 5-10g's I think.

It's hard to find airframe kits in Australia because of covid, so I'm hoping this will be a good option.

Anyway thanks for reading and any help is much appreciated

 

[BigMacDaddy]

Why not print in ABS or PETG? PLA is very susceptible to melting -- even just being in a car or in the sun for a little while can distort it and it is definitely not going to hold up to the heat produced by the motor as well as some other materials.

Are you planning to print the fins as part of fin can? I have seen a fair amount of 3D printed fins that got distorted due to high-speed flight. Is there a reason that you want to print the fins instead of printing a slotted boat tail or something can that takes plywood fins?

 

[Ronz Rocketz]

Since it's a mailer tube, why not make it longer?

I bought a 1010 rail from Granger that came in this awesome mailer tube that I've been saving. Been thinking of making something big, maybe a Mean Machine with an F motor.

 

[OzHybrid]

Where are you launching? Which club are you with?

 

[OverTheTop]

Just wondering if anyone has done a similar scratch build rocket, using a H or I motor....

I have seen a lot of uni students and even some high-school students do this. Printed fincan and NC, in PLA or PLA+. Some look a bit rougher than others, but the flights are largely successful. Even the rail guides are 3D printed and glued to the airframe.

 

[Pepe Le Pew]

Give it a whir Vonkrumml! I used a 4" mailing tube from Staples and printed a nosecone from PLA, 4 layers so I would not have a weak nosecone or have to add weight to it. 5mm light ply from Home Depot and flew it with a G57 first flight. No issues. H motors next month.

 

[tsmith1315]

Fiberglass isn't necessary, neither is keeping it in the 5-10G range. At 0.07", your mailer tube is 2x the thickness of LOC cardboard tubing.

However, if your .ork file is faithful to the rocket's measurements, 7500' with motor ejection may not be a great choice for a certification flight profile since it must be recovered.

 

[rharshberger]

Fiberglass isn't necessary, neither is keeping it in the 5-10G range. At 0.07", your mailer tube is 2x the thickness of LOC cardboard tubing.

However, if your .ork file is faithful to the rocket's measurements, 7500' with motor ejection may not be a great choice for a certification flight profile since it must be recovered.

+1, definitely no need for fiberglass and 7500' is very high for visual tracking (it can be done but is easily lost track of).

 

[Vonkrumm]

Thank you for your messages, I will take all suggestions on board!
There is no local club here but looking to travel to tripoli victoria.

Yes PETG or ABS looks like a better material than PLA (edited)

Warping of PLA wings and PLA motor mount does sound like a problem. Might need a phenolic or cardboard motor tube, something that won’t melt. (Edited)

These things really hook along don't they. The local shop is all out of H motors, so I might be stuck with using an I motor!

Slow and steady hey

 

[OverTheTop]

I use ABS for rockets but have never had problems with warping. Proper ABS should be better than PETG and PLA if the printer is working properly I think.

 

[jqavins]

Warping of ABS wings and ABS motor mount does sound like a problem. Might need a phenolic or paper motor tube.

If these statements are meant to be connected then I'm missing something. And why would you need to downgrade the body tube?

 

[Pepe Le Pew]

I'm lost too.....

 

[Vonkrumm]

I had the materials incorrect, sorry, made edits.

 

[OzHybrid]

If you need anything printed in ABS, let me know. That's all I print in.

 

[OzHybrid]

Does anyone know why ABS Plus doesn't dissolve in acetone? It burns like ABS, the fumes smell like ABS and it prints like ABS.

 

[Vonkrumm]

Oh nice! Yeah I will let you know if I need any, thanks for the offer. I have done a bit of printing, but it seems like another skill that takes time to master.

 

[jqavins]

Does anyone know why ABS Plus doesn't dissolve in acetone? It burns like ABS, the fumes smell like ABS and it prints like ABS.

Undoubtedly something in its composition; duh. But what? I did a little googling to find just what it's composition is, and the best I could find is from a Reddit post:

There’s no standard within the plastics industry for an abs+. Unless you have a comparable TDS, who knows what the differences are, if any. Luckily the industry is moving towards a greater prevalence of TDS availability, and standardized data, but I mostly see it with the bigger names right now, probably due to the cost of testing.

So as far as I can tell, the answer to your question is .

 

[rlburdett]

Thank you for your messages, I will take all suggestions on board!
There is no local club here but looking to travel to tripoli victoria.

Yes PETG or ABS looks like a better material than PLA (edited)

Warping of PLA wings and PLA motor mount does sound like a problem. Might need a phenolic or cardboard motor tube, something that won’t melt. (Edited)

These things really hook along don't they. The local shop is all out of H motors, so I might be stuck with using an I motor!

Slow and steady hey

Have you seen https://www.thingiverse.com/thing:3164819/files

Checked baggage rocket. I just built and plan to fly in July with an I218-8

 

[OzHybrid]

Have you seen https://www.thingiverse.com/thing:3164819/files

Checked baggage rocket. I just built and plan to fly in July with an I218-8

How many screws are in it? Are the nuts recessed into the mate? I count 64. no nuts.

 

[OverTheTop]

Looks like a mob of screws and some 6-32 heat-set nuts in the parts list.