HPR Custom Build

[thzero]

Got the external filets done with the some RocketPoxy.



Then started tested the tip to tip glassing on failed tube and scraps. Just kept it simple for this trail. First scuffed up the tube and the fin. Then mixed up some West epoxy and 204 hardener, and wetted the tube and fin. Laid down the small scrap of fiberglass cloth, and tapped it down lightly with a brush. Then wetted out the cloth again. Checked on it occasionally and wetted as needed.

 

[thzero]

Also got the two tubes and nose cone primed after some patching of bunch of pinholes in the epoxy (grrr... as bad as filling in spirals).

 

[Banzai88]

Nice thread so far.

I'm becoming familiar with filling pin holes! Although it's more critical for me since my goal was to use a colored sleeve and avoid the weight of paint except on the nose and fins.

My Soller sleeved project is a 4 inch, so no shrink sleeve.....and pin holes have become the bane of this project.

 

[thzero]

Thanks.

Yes, that is what I was initially planning... but Soller's "blue" was not what I had in mind. So went back to planning to paint it.

Did you try the denatured alcohol misting trick? I ran across that somewhere; tried it a bit myself and it seemed to help

 

[Banzai88]

Thanks.

Yes, that is what I was initially planning... but Soller's "blue" was not what I had in mind. So went back to planning to paint it.

Did you try the denatured alcohol misting trick? I ran across that somewhere; tried it a bit myself and it seemed to help

Ha.....their purple wasn't nearly purple, either! More a dark blue. And the weave showed the blotchy under tube....so I used a deep purple alcohol ink to base coat the tube and 10 drops per pump of 105 to sorta tint the resin, too. Came out acceptable, overall.

I hit upon the alcohol idea after the current coat. I'll try it for the final top skim coat.

 

[thzero]

Hadn't thought about that... nice recovery. I'll keep that in mind if I ever do this technique again (changes are approaching 0 of that happening again).

 

[Banzai88]

This will get a 400/600/1000 grit sanding, then a final skim coat, which will be polished.

 

[thzero]

Should look nice once you put all that effort into it

 

[Banzai88]

Should look nice once you put all that effort into it

Labor of love. Although, like you, I'm doubtful that I'll do it this way ever again.

 

[Banzai88]

Should look nice once you put all that effort into it

Labor of love. Although, like you, I'm doubtful that I'll do it this way ever again.

Sad to report that today, the music died.

After the 600 grit sanding, an ultra deep cleaning, and a final skim coat...there are billions and billions of tiny pin holes. They've seemingly absorbed the sanding dust and nothing will get the white dust out. I've tried everything. A test overcoat with ultra thinned epoxy only served to encapsulate it permanently and ruin the effect of clear resin and a visible weave in the sock.

Structurally the tube is amazing.....so it's going to get some high build primer and a coat of pain. Time to make it the originally intended purple!

C'est la vie

 

[thzero]

Yeah, I've ruled out doing anything like this for my level 2!

 

[thzero]

Well, at least you gave it a try! If I ever did it again, think I'd try it with peel ply first that way it has texture for the next layer of epoxy.

 

[Banzai88]

I was working with naked 4" tubes and had the same issue you did working with 3" tubes and shrink.

I think that the only viable solution to full saturation of the sock would probably be vacuum bagging. I've done half a dozen simple standard cloth lay ups, NEVER had this pin hole issue, with or without peel ply. I think that the weave of the Soller sock wants a LOT of epoxy and a LOT of compression during cure.

I'll probably use this rocket for my L2 launch. It's certainly sturdy enough! I mean, they used to do L3 builds with cloth wrapped cardboard!

 

[Banzai88]

Maybe this is the way?

 

[thzero]

I was working with naked 4" tubes and had the same issue you did working with 3" tubes and shrink.

I think that the only viable solution to full saturation of the sock would probably be vacuum bagging. I've done half a dozen simple standard cloth lay ups, NEVER had this pin hole issue, with or without peel ply. I think that the weave of the Soller sock wants a LOT of epoxy and a LOT of compression during cure.

I'll probably use this rocket for my L2 launch. It's certainly sturdy enough! I mean, they used to do L3 builds with cloth wrapped cardboard!

Yeah, I would agree with you on all points. Looking at the outcome of my test of doing layup for the tip-to-tip fiberglassing of the fins, I had zero pin holes with it - too much epoxy, but still. Think its the size difference, there isn't the big holes with the cloth that you see with the sock - think the latter contributes.

Wow... wish I had that setup!

 

[thzero]

Regarding tip-to-tip glassing of the fins, I've been pouring over this YouTube video as its best walkthrough I've seen

https://www.google.com/search?q=tip...i61j69i65l2.1455j0j7&sourceid=chrome&ie=UTF-8
I don't think on my build, based on the performance characteristics for the 38mm motors, I need as many layers so just going to head towards one layer.

When, or if, I do the 54mm fin can, which with some of the bigger motors is up over 1400f/s per sim, then I think that probably qualifies for a bit more structure like shown.

 

[thzero]

Still pondering with the tip-to-tip fiberglass if I really need to do internal filets between the body tube and the TTW fin tab. There are filets between the TTW fin tab and the motor tube, and there will be tip-to-tip which essentially binds the fin to the body tube. Thinking the internal filets to the body tube is just extra weight at that point.

 

[user 30299]

I was working with naked 4" tubes and had the same issue you did working with 3" tubes and shrink.

I think that the only viable solution to full saturation of the sock would probably be vacuum bagging. I've done half a dozen simple standard cloth lay ups, NEVER had this pin hole issue, with or without peel ply. I think that the weave of the Soller sock wants a LOT of epoxy and a LOT of compression during cure.

I'll probably use this rocket for my L2 launch. It's certainly sturdy enough! I mean, they used to do L3 builds with cloth wrapped cardboard!

They still do L3 builds with just cardboard - no cloth wrapping required.

 

[Banzai88]

Regarding tip-to-tip glassing of the fins, I've been pouring over this YouTube video as its best walkthrough I've seen

https://www.google.com/search?q=tip...i61j69i65l2.1455j0j7&sourceid=chrome&ie=UTF-8
I don't think on my build, based on the performance characteristics for the 38mm motors, I need as many layers so just going to head towards one layer.

When, or if, I do the 54mm fin can, which with some of the bigger motors is up over 1400f/s per sim, then I think that probably qualifies for a bit more structure like shown.

That's the video that I learned T2T from, too. No issues there. I think that, pretty much, T2T is based on as much what/how fast your landing on as what speed you're going to hit going up.

I did a T2T on my 3" 38mm motor mount Thor since I was concerned about fin flutter on 1/8" fins. Turns out that T2T was overkill, by a large margin! But, HEY I learned a new skill. !/4" fins, just about any shape you could make is going to be OK without T2T as long as you're sub mach.

And as for hitting Mach+, there are proven fin shapes for altitude/speed seekers that work best overall without T2T, and plenty of folks do it.

Heck, some few years ago when the fiberglass Go Devil was the 38mm Min Diameter speed/altitude seeker of choice, folks did plenty of Mach+ 10K feet launches with the 1/16" fiberglass fins, surface mount, and simple rocketpoxy fillets!

These days, I only do T2T for landing on potentially hard surfaces or if I'm expecting speed and committed to long, thin fins. Otherwise, I find the trade off to 1/4" fins worth the trade off in NOT having to do fiberglass work.

 

[Banzai88]

Still pondering with the tip-to-tip fiberglass if I really need to do internal filets between the body tube and the TTW fin tab. There are filets between the TTW fin tab and the motor tube, and there will be tip-to-tip which essentially binds the fin to the body tube. Thinking the internal filets to the body tube is just extra weight at that point.

Generally it's considered that the ONLY fillets that are going to matter for strength of the mount are between the fin tab and the motor tube. With a T2T layup, you could probably get away with a generous 'double butter, double dip' type application, depending on what epoxy you're using. The EXTERNAL fin fillets between the body tube and the fin root are as much for air flow as for strength, depending on the material that you use for the fillet.

 

[thzero]

Thanks, that is helpful!

 

[Banzai88]

Post final sanding mock up. All up weight comparison of my tubes shows that I'm about 10% over weight after glass/resin. Not too bad, but still too much to sand off without burn throughs to the sleeve. Oh well, I'm hoping for perfection with an imperfect process, so I guess 10% ain't bad.

 

[thzero]

Nice looking rocket.

Much better than my ratio more like 50% more. But overall weight is still within my predicted/rough guess range where I wanted it to be so there is that.

 

[thzero]

Built a 29mm mount adapter using a LOC adapter kit, and some Aeropack retainers.





Now I can screw the 29mm motor into the adapter, and then the adapter into the 38mm motor mount. Now I can use this on any 38mm Aeropack retainer rockets I build.

 

[thzero]

Took the plunge and started in the tip-to-tip fiberglass, after rewatching the above video again...

Taped up the backside to control 'leakage'.



Cut out the cloth. I used the trick of fingernail polish around the edges to cut through, that way the cloth doesn't fray.



Applied the epoxy, and waited. I had to watch it on and off until it started setting since the epoxy would want to slide down into the filets; probably should have used release fabric, that might help. But since I had already started, decided to do all three sections the same way. Overall it came out fairly well, not perfect. Will need to go over with a light coat again as there was some parts where the cloth texture is still there... just need enough epoxy to smooth out the surface. Then onto sanding.



I'll note that I pulled the tape off after the epoxy setup enough bit before it became leathery. Then once it became leathery, I took a new exacto knife and cut off the excess.

That was the first one... have the second one curing now. Then onto the third one.

 

[thzero]

Have to say, I forgot how much I detest painting! What a pain... and of course I didn't go for the simple one color paint only scheme.

 

[thzero]

Well spent some more time working on the ebay.



Then we have the individual sleds.. one for the Missileworks RRC3 and the other for the Featherweight Raven



And then the put together. Still need to start on the wiring, and build a battery rest and block for the Raven's battery





Am probably going to have a set of holes of a zip tie to give extra hold to the battery. Also tweaked the design file a bit to space out the battery holder and the RRC3 a bit more on the sled.

 

[thzero]

And then I've completed painting... looking at sticker shock for some decals to use, and trying to come up with a good name for it.

Mostly primered...



And then the paint job.... wanted something different from my usual blue/green and black/red paintjobs, so took some inspiration from sounding rockets, roll patterns, etc. Its not perfect, but what actual rocket is?!. From 10' the paint job looks pretty good although may still need to work a bit on the nosecone.

 

[thzero]

I drew up the wiring diagram for the eventual full electronics bay, learning Kicad (at least some of it) as I was doing so.



But here is what I'm going to concentrate on for the first flight... main at apogee, motor backup, plumbed for drogue but will probably go with the Jolly Logic but we'll see.

 

[thzero]

Add some stickershock23 stickers and others to give it a bit of the 'sounding rocket' vibe.









Then I realized I forgot to put in the rail guides... doh! Not too big of deal, as they were going to go on the lower tube anyways to make it easier to switch out the fin cans.