2.63" (formerly 3" Mailing) Tube Printed Rocket

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thzero

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Well after some printing issues, I finally have 3 fins! And it worked. I am considering creating mold of these to make creating replacements easier! Also, thinking of putting a layer of fiberglassing on the fins.

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thzero

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The recovery hardpoint. Its meant to be glued to the motor mount tube and then screwed into the sidewalls of the outside tube. I had a previous version that was just going to be screwed to the outside tube only, however I was a bit concerned about forces torqueing on the tube and causing it to buckle or crinkle.

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thzero

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Started on the nose cone

PXL_20210225_125915096.jpg


And then the bottom which has the attachment point for a bulkhead that will have a eyebolt for recovery attachment. It also allows for holding a gps, and/or altimeter within the nose cone. Working on that sled to hold both the gps and altimeter - its based on the size of a bt60 body tube (for reuse in some of my other rockets)

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thzero

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More progress... ground down the t-nuts to fit. Went with t-nuts over inserts as there are only two, and this gives a mechanical support for the forces acting on the motor retention ring. Retention just bolts up with button headed bolts; with a dab of blue loctite.

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And then same for the bottom of the nose cone. The center circumference is the ID of a BT-60 tube; have some BT-60 based altimeter/gps payload sleds that I plan to reuse and this was almost a prefect fit.

Then I'll have just a standard plywood bulkhead with a eyebolt attached to it; bulkhead will attach with hex button bolts to the t-nuts with a dab of blue loctite; used this a lot with my other mid and smaller high power rockets.

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thzero

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And then after many many hours of printing (and an issue with the 3d printer), the three pieces of the nose cone. Tallest print I've done, and looks like I still need some adjustment towards the top as I got a very slight wobble in x/y axis. However, it does look worse in the picture than it is. A bit of sanding, and I think I'll do a single layer of fiberglass and it'll be good to go.

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The bottom and mid pieces will be epoxied together; not sure the mechanical lock will do anything, but it does work so I'm happy with that.

The nose cone tip will be replaceable; I'm sure it'll get beat up. Just going to epoxy a nut into it then use a bolt and washer to screw it much like we do with fiberglass nose cones.

And all three together... looks like a nose cone!

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thzero

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Fully loaded as it stands now, we are looking at about 32.4oz on a G-64. Compared to one of my 54mm LOC builds that is roughly equivalent that's 25.1oz. on a G-64. Or my level 1 (fiberglass, plastic nose cone, motor mount and rings were carboard/plywood) weight in with G-64 at 35.4oz.

So not too bad.

On G-64, looks like about 1300'... which given some of my launch sites (cough NIRA) is just fine. H123 puts it at 2900', and H180 puts it at 2662'. I*s are all in the 3000-4000' range.
 

thzero

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Yup. In this case, the kevlar shock chord I'm using has a sewn loop in it already, so I'll just put looping the chord through and no quick link.

That is one nice thing here, the motor mount will just unbolt from the tube and can be removed so replacement in this case will be a snap. Also also a damaged body tube, fin, etc. to be replaced pretty easily.

If you are going to use a quick link, be sure this hard point has adequate clearance to attach it, or you'll just have to tie to it, not that it is a problem.

I am forever finding out how my hands won't fit into certain places.
 

Donnager

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...the motor mount will just unbolt from the tube and can be removed so replacement in this case will be a snap. Also also a damaged body tube, fin, etc. to be replaced pretty easily.
Nice.
 

thzero

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Have the tip setup to mount into the nose cone. Decided to go the opposite direction and epoxy a threaded rod (#10-24) into the tip, then attach the bolt onto the threaded rod. This is as opposed to metal tips where the bolt is screwed into the tip itself.

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Then shot of the flat washer bolted in with a lock nut.

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thzero

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The internal motor mount structure... just need to glue it up.

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Did introduce a "heat break" so the metal of the motor bottom ring isn't directly against the plastic. Was going to use some carboard of about the thickness of the tubing, but didn't find any handy so just used a spare ring.

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thzero

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Power core is basically finished

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From the business end

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\\

With the motor.. this is a 38mm motor, am planning to have a 29mm adapter for 29mm motors

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And with the retainer bolted on.

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thzero

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Shock chord attached to power module.... fun saying power module!

View attachment 453655


Power module (tim the toolman sounds) bolted in for mockup!

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Shock chord attached to nose cone.

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Nose cone locked together and mostly assembled again for mock-up purposes. Need to make sure I put on the rail buttons and get the gps/altimeter sled printed out, and want to fiberglass cover the fins (just bit more strength), then some finishing work and should be ready to fly!

View attachment 453659
 

thzero

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Shock chord attached to power module.... fun saying power module!

PXL_20210304_214138867.jpg



Power module (tim the toolman sounds) bolted in for mockup!



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Shock chord attached to nose cone.

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Nose cone locked together and mostly assembled again for mock-up purposes. Need to make sure I put on the rail buttons and get the gps/altimeter sled printed out, and want to fiberglass cover the fins (just bit more strength), then some finishing work and should be ready to fly!

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Dustin Lobner

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Got a chance to read through it. Awesome stuff!

Can I ask, what kind of thermal inserts did you use? There's a ton of variety out there...PLA generally taps really well, but I've been moving to PETG and it SUCKS to tap PETG, so I've been looking into PETG. I know some inserts are better at torque resistance, others at pulling out, etc...
 

thzero

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Honestly just some random brass inserts from Amazon. Guess we'll see what they do. Bit leary, probably wouldn't use it for more than this small stuff. I did do a redesign of the fincan to use t-nuts so that there is more of a mechanical attachment point.
 

thzero

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Started fiberglassing the fins

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Without ply peel.... I had forgotten about doing that when I started the first one.

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Next two were done with ply peel...

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And you can see the difference (a bit)... but definetly will do the rest with the ply peel. I'm going to try and use some Smooth On XTC-3D anyways, so I think that will give a nice final surface (and with the color dyes, it'll be pre-colored!) - will need to experiment, thankfully have a bunch of old 3d test print pieces to try on!

Ply peel on the left, without on the right.

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thzero

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Printed up some 29mm to 38mm adapter parts, and a new motor retention component for 29mm. Looking to send it up on an F and G tomorrow, then inspect, etc. If everything is looks good, hoping to go with an H.

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thzero

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On the launch pad...

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And the launch... not very good video, but was on a time limit. The launch was successful, with a good recovery. Everything is intact and checked out - am planning to unbolt it and check out the insides.

 

thzero

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And the business end of the retainer... isn't too bad; most of the burnt residue is from the masking tape used to secure the igniter wires.

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thzero

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Disassembled the rocket in order to do some paint - not often you get to say that with a model rocket. Another reason for disassembly was to see what the effects of the ejection charge had if any, as well as check the fin mounts for any damage, etc. All is look pretty good.

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thzero

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Disassembled....

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And yup thats the same rocket *after* I had launched it..

 

thzero

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Got a chance again to launch the rocket yesterday. Had two really good flights on G-64s. Next up for next month's launch will be a H128.

Put together a video from the flight. Unfortunately the in flight video did not record.

 
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