MPR Scratch Build Rockets for the kids

[pugachu]

Years ago, I got a deal on a box of RMS 24/40 loads, so I got tons of E18's and E24's. I don't have many rockets that fit into that size. My kids are starting to enjoy rockets (ages 6-11) and I thought I'd build some rockets for them to use these engines.

These rockets are made from some 1.5" shipping tubes, along with 3d printed nose, and 29mm LOC motor mount. I don't plan on putting a G in them, but it's nice to have the option. I SLA 3d printed the centering rings, and cut the baffle sections out of 3/32" plywood. The nosecones are similar to LOC 38mm plastic nosecones, but I am FDM printing them. The tube couplers are made from the shipping tube, with a slot cut into it to reduce the diameter. the inside is epoxied to seal up the slot. I'm making 3 identical rockets, and then letting the kids paint them. I have the kids build Estes rockets, but as these are going on E-F reloads, and I have a time constraint for getting these finished, so I'm building this batch.

I am in the early stages of the build. the centering rings and #4-40 allthread (for motor retention) are bonded to the mmt, the tube couplers are made and glued into the lower airframe. The nosecones are about 60# done printing. I like to make rockets with the zipperless design, even though these are small enough not to really be a concern. I am putting ejection baffles in, so that we don't have to worry about wadding or parachute protectors.

I know these are overbuilt, quite a bit. My kids are rough on stuff, and have destroyed several Estes rockets while waiting for the pads to be free. I plan on fiberglassing the basswood fins for the same reason. I'll post the simulations this evening.

Thanks for looking.

 

[pugachu]

It's been a few days since my earlier post. The noses are finished printing. I've added an ejection baffle to remove the need for wadding or a parachute protector, and I've drawn out the template for the fins. The couplers are epoxied into the lower airframe, as well as the motor mount tube and threaded rod for motor retention. I used aluminum threaded rod to save on weight. I will be machining the acorn nut into a small eyenut. Detailed pictures will be posted when those are complete. I couldn't find 1/8" ply at Ace, so I got 3/32" thick basswood, which I will be throwing on a layer of 4oz fiberglass. I know the glass won't be required for the flights, but again, my kids are rough on stuff. Pre-COVID, they were digging holes with the nosecones of their rockets while waiting to fly. Once the fins are on, I'll update the simulation weights.

 

[pugachu]

The fins have been attached, as well as the 3/16" launch rod guides. Next is filling the spirals, priming, and then letting the kids paint them and put stickers on.

Rocksim simulates these going to 1,700' on an E, 2,100' on an F39, and 2,900' on a F40. They will take an estes D12-3, but would only go 500'

 

[Pepe Le Pew]

Very cool Brian, keep teaching the kids rocketry, especially other than traditional materials. I am an avid scratcher and love building with other that traditional materials.

 

[pugachu]

Thanks for replying, i lost interest in making more updates, cause it looked like no one was interested in reading about them. The rockets got finished and painted, and we flew one on an E28T. The 24/40 casing got kicked out and lost. We spent precious flying time looking for the casing before giving up.

I tried to fly the second one on a D9W, but the motor chuffed and burnt the igniter. The D9 has a tiny nozzle, so i had to rebuild the motor with a new starter. I sanded the charring off the slot put a sliver of blue thunder for next time.

It gets hot early here in the Sonoran desert in June, so we ran out of time to fly. We will try again next month (August)

 

[jmasterj]

Did you figure out how the motor got kicked past your retention?

Looks like a fun time with the kids!

 

[lakeroadster]

Thanks for replying, i lost interest in making more updates, cause it looked like no one was interested in reading about them. The rockets got finished and painted, and we flew one on an E28T. The 24/40 casing got kicked out and lost. We spent precious flying time looking for the casing before giving up.

I tried to fly the second one on a D9W, but the motor chuffed and burnt the igniter. The D9 has a tiny nozzle, so i had to rebuild the motor with a new starter. I sanded the charring off the slot put a sliver of blue thunder for next time.

It gets hot early here in the Sonoran desert in June, so we ran out of time to fly. We will try again next month (August)

Neat little rockets. Kudos to you for making an airframe that fits the motor, and doing it in an unconventional size.

 

[Pepe Le Pew]

The rockets look great!!! The kids look excited and it looks like a good time. I 3d print all my NC's, I get my tubes from Staples, Skycraft Surplus and my fin plywood from HD or Lowes. keep building and flying with the kids, someone did it for us and.... here we are!

 

[pugachu]

Did you figure out how the motor got kicked past your retention?

Looks like a fun time with the kids!

The retention for the 24mm-29mm adapter is just an Estes style motor hook, while that adapter was held in place with the nuts and threaded rod. For the next flights, I will use some wire wrapped around the threaded rod, across the nozzle, and back to the other side to tie it in.

 

[jmasterj]

The retention for the 24mm-29mm adapter is just an Estes style motor hook, while that adapter was held in place with the nuts and threaded rod. For the next flights, I will use some wire wrapped around the threaded rod, across the nozzle, and back to the other side to tie it in.

Ah, gotcha. Aluminum tape is good for wrapping as well.

 

[86mustang408w]

Cool topic, glad they are getting into it. And building your own is priceless! Really looking forward to flight videos! I've always still used a little wadding or dog barf for my low power with baffles, guess I don't but I'm paranoid! Just did a Big Daddy with nosecone mods and its great I love putting your own twist on rockets. Love that your sharing it with the young ones, my niece and I used to build and fly them. I'm hoping she gets back into them one day...Great job man!

 

[novahobbies]

Thanks for replying, i lost interest in making more updates, cause it looked like no one was interested in reading about them.

I know that feeling, sometimes I feel like I'm just posting to the ether. It's not that people don't read, it's just that these days not many of us respond. I'm guilty of it as well. I think it's the FB/Instagram mentality, we just scroll and smile, then keep scrolling.

I'm interested, you mentioned you sla-printed your centering rings? What kind of resin were you using? I have both resin and FDM printers, and I would have thought printing the centering rings on the FDM printer would be better than resin. To date, I've never printed anything load bearing for rockets. Just nose cones and various little things.

 

[pugachu]

I used a formlabs resin printer for the centering rings, as they end up much more round than my FDM printer can do. I have a cheap belt driven FDM printer, and there is slop in the drive, so i end up with egg shaped round features, especially with small diameters. The SLA parts are brittle, so i make them thick. I use plywood for load bearing HPR centering rings.

 

[novahobbies]

I used a formlabs resin printer for the centering rings, as they end up much more round than my FDM printer can do. I have a cheap belt driven FDM printer, and there is slop in the drive, so i end up with egg shaped round features, especially with small diameters. The SLA parts are brittle, so i make them thick. I use plywood for load bearing HPR centering rings.

Ah that makes sense, so you still use old school to make sure the motor mount doesn't try to become an internal rocket on its own, and the resin ones are just to help. I was worried about heat so that explains a lot, thanks. From what I can find online, it's true that resin might be overall better for the temperatures involved. Siraya Tech has a heat resistant that can withstand 160c temps. But Estes BP motors can reach up to 200c occasionally, so I'd be cautious. Don't think it would stop me from trying! Heh.

Also......tighten up those belts, or else get yourself a new FDM! LOL. I've got a Neptune 3 and I'm still learning the ropes there, but I DO quite like it.

 

[pugachu]

2 months ago, we lost my oldest son's rocket to the wind on an E28. I asked him to help me design the replacement. It's almost done now. The tube is from an AT J425R packaging. 1 7/8" OD, 1 3/4" ID. Printed nose and boat tail. He wanted 4 fins, and the shape similar to V2 fins, but with an elliptical nose. Tonight ill be spraying it with primer, then he can paint it tomorrow. Plan on flying it this weekend.

I should be bringing my DSLR, so I'll try to get a liftoff shot.

 

[bad_idea]

Well done. Always love a repurposed-motor canister rocket.

 

[Wrightme43]

2 months ago, we lost my oldest son's rocket to the wind on an E28. I asked him to help me design the replacement. It's almost done now. The tube is from an AT J425R packaging. 1 7/8" OD, 1 3/4" ID. Printed nose and boat tail. He wanted 4 fins, and the shape similar to V2 fins, but with an elliptical nose. Tonight ill be spraying it with primer, then he can paint it tomorrow. Plan on flying it this weekend.

I should be bringing my DSLR, so I'll try to get a liftoff shot.

I love the tailcone. Thats a cool design.

 

[pugachu]

Here are the pics from Oktoberfest in Jean NV. Malachi's CATOed on a D9W, Lilandra's flew on a F20W, and my oldest, Eloden's flew on an E28T and then a F20W