First HPR 2 Stage build

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Well-Known Member
Jun 19, 2017
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Vacaville, CA
I started enjoying the more complex side of rocketry. So, I started building my first big staged rocket (I’m not counting my Comanche 3). I picked up a box of random 3” tubes. I wasn’t sure what they came from until I seen PML on the inside of some of the tubes. I went online and was browsing 3” kits with these lengths of tubes. It appeared that I had most of a PML Quantum Leap II. I picked up a Fiberglass/gelcoat nose cone from Performance Rocketry, and a section of 3" phenolic for the booster section. I’m not sure what the outcome will be exactly. But I did some rough Rocksim mockups and its looking good. This rocket will be 116” tall and weigh 11 pounds. After separation, the sustainer will be 81” and 6.5 pounds. Those weights include everything except motor. I am still unsure if I will cut down the 26” payload section and maybe a little off the drogue bay. Currently she will stand 2 feet taller than the Quantum leap.

I was unsure if I wanted to leave the tubes alone or glass them. I am still sanding the wrap job on my HyperLOC 835. I ended up calling Solar composites and buying some biaxial sleeve and their heat shrink. I was mostly happy with that process. One tube the heat shrink pulled to short and the lower inch of the tube wasn’t covered. The second tube I melted a small hole in the heat shrink and had some epoxy squeeze out. The third tube came out perfect. The first two tubes required a decent amount of clean up and pin hole filling. I need to figure out how to prevent all the pin holes.

The motor mount tube had previously been mounted in the sustainer body with the top two centering rings. The top was sealed with its coupler, bulkhead, eyebolt and plenty of epoxy. Only allowing the use of a plugged motor. It appeared to be set up for a zipper less tube that separated at the bottom. But I wasn’t a fan, So I vented the motor mount tube and bonded the two tubes together prior to glassing. I prefer the stiffer rocket over being able to disassemble it more.

I made an aft CR, and sanded to fit. Drilled a hole in the CR and through both middle and upper CR. With the sustainer ignition conduit installed it will sit .25" bellow the Aeropack retainer. It will be a tight fit, but there will be a bit over .10" between the aeropack retainer and the interstage coupler.
One post and I already love this thread. What are you planning for electronics?
I picked up a sheet of 1/8” fiberglass from Wildman to make some fins. I ended up using some of the sheet for another project and only had enough for the sustainer fins. I did not stick to the QL2 fin design. Kind of went with a Nike Smoke fin shape. I hit the belt sander and airfoiled the fins as perfectly as I could freehand them.

For the booster fins I wanted to make them a little bigger and draggier. I am hoping to get a good drag separation and not need the installed separation charge. I went with ¼” plywood and air foiled them to a lesser extent of the sustainer fins. I am still undecided if I want (or need) to glass them, or do a tip to tip. Input on that for booster stage???

More sanding an filling on the tubes is needed. I have exposed the original fin slots, but still need to cut them open.

I had a thought run through my head. Would it be a better performer if i built it as a 3 fin? Changing it to 3 fins in Rocksim didn't reduce the stability much.
For electronics:
Booster (interstage coupler), Eggfinder TRS for DD and tracking booster. With an ARTS2 for sustainer separation charge 2 seconds after MECO, and back up apogee deployment.

Sustainer Avbay, RRC3 for drogue and main with the AUX channel igniting the sustainer stage. Quark as redundant deployment.
Nosecone, Eggfinder Mini for tracking sustainer.

I'm hoping and planning for drag separation. But I will run a .3g separation charge in the top of the interstage coupler.
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I had a thought run through my head. Would it be a better performer if i built it as a 3 fin? Changing it to 3 fins in Rocksim didn't reduce the stability much.

Yes, definitely. For a basic 3FNC rocket I simmed in OR at Mach 1.2, each fin was about 10% of the total drag. So switching to 3 fins should give you a 10% drag reduction, more or less.
I will have to decide soon. I'm about ready to cut the fin slots. Now I'm really thinking about making it 3 fins, instead of 4.

Sent from my VS988 using Tapatalk
I took a break from filling and sanding the glassed tubes. I was able to get some work done on the sustainer Avbay. The amount of room in the drouge bay seamed small. So I offset the avbay up to give me more space. I will probably just wire charges directly to altimeters and seal the bay with tack puddy. Not sure if I will install charge wells. I have been happy with glove finger tip charges that I place above or below recovery, depending on location and situation.

I will be using the RRC3 for primary deployments and sustainer ignition. Powered by 9V Duracell with a screw switch. The Quark will be back-up deployment at +2seconds and -200 feet. Powered by a 200 mAh 2S, with a screw switch.

I have 3 vent holes, and 2 of them line up with the screw switches using the tinny screw driver to turn on altimeters.

Sent from my VS988 using Tapatalk
So I haven't worked on this rocket in about 6 months. When I had tried to do more filling and sanding of the fiberglass pinholes. Kept having issues with the filler and primer that was already down. So I gave up for another 6 months.

I did some measuring and marking and cut some fin slots with the dremel cutoff wheel.


Then I came up with a name for this rocket. It will be "Grayscale" . After building several fiberglass kits in the last year. I have decided I won't be glassing my own tubes anymore. Not worth it for me. So thess pinholes are staying and it will get a grayscale texture. I sprayed a really heavy base coat of gray. Then recoated it 8 hours later with a different shade of gray. Completely outside of the recoat window. And I got the wrinkles that I was looking for. Waited 4 more hours and applied two more shades of gray in a pattern of sorts.



I will tack the fins in next. They probably won't receive big smooth fillets like I have been doing lately. Just needed to get this pile of tube out of the corner.
I installed the sustainer ignition conduit.
I had a couple Aeropack retainer bases set aside for this rocket. Then they got used on some recent Mach 1 kits.


I'm not sure if I still want Aeropack retainers. I left the conduit 1" bellow the motor mount for clearance. But it will be a tight fit. Also with redundant altimeters, I will just fly the motor plugged and not need anything more then friction for aft retention.

The aft centering ring was installed for conduit alignment. Internal fillets will have to injected. The aft centering ring will also only have epoxy on the forward side. The interstage coupler will butt flush against it.
I really like the paint..but that will absolutely disappear in the sky...Sounds like you have tracking under control though.
I really like the paint..but that will absolutely disappear in the sky...Sounds like you have tracking under control though.

Thanks. Lol, yes... The cloud cover camo will keep visual tracking fun. But I do plan on GPS in both sections.
Booster and sustainer fins are tacked on with BSI 30 minute.


Also the interstage coupler got its switch band epoxied in place. I had to wait until the sustainer aft centering ring was installed. The coupler and switch sit level against the sustainer at the same time.


I will start doing external fillets next. Then to finish the paint.

I was thinking about keeping the fins and nosecone black. Thoughts? Should the switch bands also be black?
The last couple days I spent doing external fillets. All the joints were scuffed with 60 grit, then whiped with acetone. I masked everything off real nice to give me the size of fillet I wanted.

I did a side of the booster and sustainer at the same time.


After 5-10 minutes the masking tape was removed. Then about 10 minutes later a gloved thumb diped in IPA smoothed them out to a good shape.


After the fillet epoxy started getting real firm. I mixed up 2 pumps of West System and poured it into the internal cavity. Then installed the aft centering ring all the way to the fin tabs. I rotated the rocket in every direction to spread the epoxy evenly.

The aft side of the centering ring and inside surface of the body was coated with West as well.

Then JB weld was mixed up and applied to the MMT and printed retainer base.


Then both pieces went into the oven for curing.

Is that West with a filler?
I started with Rocketpoxy. After doing the first set. It looks like my jars were running low. Unless I did really small fillets. So half of the fillets are Metalset A4 and half are Rocketpoxy. Alternated sides, so each fin has a fillet of each epoxy.
Now there's an interesting test....

My hypothesis is that since the metalset is stiffer then the Rocketpoxy. It will cancel out any harmonics and eliminate fin flutter.

But I have no real clue what I'm doing. Just having fun and winging it.
I flew "Gray Scale's" sustainer on an H250G I assembled earlier in the year and wasn't able to fly in another rocket. It was a good test to check its stability and see if it would spin. It flew perfectly straight up to 950'.



I just had the payload and nose friction fit since they were empty. I will use screws next time. The payload tube separated from the coupler and did a nosedive. No damage done. Just received a little education on how tight friction might not be good enough.




I think I will start prepping a 2 stage flight for early next year. If I can get this RRC3 working right.
So.... Since the sustainer flew so straight on an H250G. I decided it was two stage time. So I loaded up a couple motors that are a little bigger.

I decided to go with a CTI K740 C-Star booster, to an Aerotech K185 sustainer.

Booster had a Quantum in Airstart mode for separation charge and apogee deployment. Used the motor delay as back-up ejection and had the booster chute on a chute release.

The sustainer had an RRC3 for shagging and apogee deployment, with another Quantum as backup deployment. The main chute was in the forward payload on a chute release as well.

The flight went great. 2.5sec boost. .5 sec sap charge delay. 5 second coast. Then 7.5 second sustainer burn to 14,700'.

It's very tall on the pad.

Blasted of the pad with great authority.

Perfect drag separation right after MECO. And sustainer ignition.

Good piece of advice.... Don't pip the main chute at 14,700 feet. I'm not sure how the Chute Release came of early. But it drifted over 6 miles down range.


Good thing I had an amazing Eggfinder Mini in the nose. Never lost signal and displayed up to 24,500' as we were heading out to recover.


Thank God for friends with recovery UTV's and for soft risked soil.

Quantum report.

Might not be possible to directly upload. Take a picture and upload system works for me..