ACR PSR 1824 Build Thread

I usually paper fins but on this one I did it the Old School way with CA/sanding sealer. The boosters fit in the fin notch and slide over the fin, so papering might get in the way. I hardened all the balsa with super thin CA.

This morning I got the fins rounded and glued onto to booster core. First image is a dry fit to check alignment vertically. I'm using a spool of teflon tape as a support. It is almost the perfect size. A little masking tape brings the fins to where I want them.

First fit as a cluster shows I have as sanding to do. As all the parts are supposed to go back together always in the same order, I've numbered the fins. I sanded the notches until they went down fully, more than actually shown in the image.

Then I had to leave for work.

UPS Tracking has my power supply in town. It should be delivered tomorrow. (It arrived late Thursday afternoon).

Next comes the lugs and pins that hold the boosters together at the top. I got the 1/16" balsa stock to the chopper and cut a 2" length. Included in that shot is my beverage of choice. A 2" length of 1/8" launch lug material gets glued to the balsa stock and from there is cut into 1/2" lengths. Those are then glued to the forward end of the booster tubes.

I was setting up the booster tubes to attach the retaining pins today. One of the fins felt real wobbly. I had to remove it and clean up the old glue from both sides. Later this week I'll get it back on.

Looking good,

This was one of my first rockets after getting back into the hobby. I'm loving seeing how someone else builds theirs! I'll post pics of mine tomorrow. I've never flown it as a full cluster (just the center) need to get the courage to fly it as intended after all the hours I out into building it.

Ok, I got my daughter all married off and re-glued that wibbly, wobbly fin. I should be able to get back to it later in the week.

judo said:

Ok, I got my daughter all married off and re-glued that wibbly, wobbly fin. I should be able to get back to it later in the week.

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Got daughter married off... was that in the instructions?... and I thought I had some quirky steps.

cosmodrome said:

Got daughter married off... was that in the instructions?... and I thought I had some quirky steps.

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Sometimes stuff just comes up in a build you have to deal with.

Booster forward mounts are completed. Launch lug pieces got glued to the balsa base. The 3/16" square balsa stock got glued to the base. Finally, the blocks were sanded round and down. Tapered end goes down and the lugs will receive a wooden alignment pin.

And that dang fin worked itself loose again.

No pictures on this one: I sanded down the alignment pins a few thousands. Hoping to get on to that real long step that gets the previous parts glued on this weekend. The faster I get that bedroom painted...

Building the ARC PSR 18/24 is not a sprint, it is a marathon, OK more like two or three marathons.

Nope. No rocket progress. Bedroom painting and fig picking instead.

I got the forward mount assemblies on. It was trickier than it sounded.

What's left should move along a bit faster. The upper half is a transition, balsa block, two body tubes, a nose cone and the recovery parts. Once that is done then it gets to be fit and fiddle with booster functionality and paint. For now I am thinking of white, orange, black and silver in a Door Knob inspired paint scheme.

The transition is going to get some abuse so I wanted to toughen it up. I gave it an coat of epoxy on the bottom of the base, through the middle, and along the outside. As previously discussed, I placed a yellow dummy tube inside the core tube as it is going to see the brunt of the ejection force. I also skipped ahead and installed the thrust ring to allow for an E12. I may never use one but I will now have the option. the transition is quite rough and will need quite a bit of finish work. I gave it two coats of epoxy and I will spray on some primer before gluing to the core tube. I feel it will be easier to work on there. At the last minute I decided to up grade from 3/16" lugs to 1/4".

After 4 coats of primer I am happy with the surface. Here it sits as the epoxy cures:


Now to find my 1/4" launch rod for lower tube lug alignment.

Be careful on the finish & paint thickness, Unless you used more tape as a guide earlier on, any build up will have to be sanded off where the boosters touch the body. Shiny and glossy paint surfaces may be a bit sticky even when dry. I found that out on my 1824.

Oh, there was copious sanding between coats. I alternated white and gray primer to fill the divots in the balsa. My plan for now is to only have color in places where tubes do not make contact. As I am going for a Door Knob inspired, sounding rocket looking paint scheme, this one is going to have a flat finish. I still owe you rocket. Keep those tips coming.

The whole reason behind the next step is to get the lower launch lug into place. I'm thankful for a few things here: God-given creativity, spare parts, rocketry experience, tools, and that this was not the first time I'd used epoxy to join parts. As alignment between the upper and lower parts is super critical, the epoxy gave me time to put plan into motion.

First, the recovery tube gets placed on the transition for a rough alignment. I gave it a "gun sight" look to get it close. I ran the rod through the lug for any final tweek. I brought the alignment line from the tube down to the transition. Here goes...

I mixed up some 30 minute epoxy and smeared it around the bottom of the tube and joined it all together.

I just was not satisfied with where the lower lug rested against the booster. I looked back to the previous steps and built up some electrical tape as a shim. I used white glue on the stand-off and rotated it into place.

The last picture shows the rocket suspended and banded and shimmed and I don't know what all else.

Getting it all lined up and sliding good is a challenge and makes it a solid skill level four.

Here you can see the payload section assembled. I epoxied the balsa bulkhead into the payload BT. The nose is friction fitted. It also had the same rough finish as the transition so it needed some care. I gave a good rubbing of wood filler, allowed that to dry, then gave it a gentle sanding. I mixed up some finishing epoxy and applied two coats, allowing curing in between. I'll have it primed sometime this week.

Here I have all my pieces parts set out for an exercise in repetition. Four notches filed into centering rings with a triangular file. Four sets of Kevlar/elastic shock cords tied to four sets of notched centering rings. Four sets of notched centering rings with attached Kevlar/elastic shock cords ready to be epoxied into four booster tubes. Four previously discussed booster tubes set aside to cure. Four previously aforementioned booster tubes completed with nose cones and streamers

I have 5 shoulders all sanded down to fit into their respective body tubes. I started to attach the provided shock cord but thought it to be 3 times shorter than I would be comfortable with. My shock cord material is stored in an outside shed now and it's been raining all day. I want to put some primer on the nose cone as well but I've long learned that spray paint and rain are poor mixes. The next pictures you are likely to see are of the finished nose and the full unpainted stack.
I need to apply fin fillets soon. I have two fins now that worry me. I still need to smooth up the fins as well. There are some other kit-specific fiddly bits yet as well. I think I can have it done by the end of the month. Yeah, that's what she said.

No pictures to follow. I got the fins sanded with a series of 150-220-320 grit papers. Need to get the deep grains filled with either wood filler or spackle and then resand. Anyone have some spare time they could send my way?
Thankfully the summer heat is waning.

Yeppers, you slap your forehead and say "I coulda had a V8!" On the 18/24 you slap your forehead and say "I coulda built Eight 3FNC rockets!"

Been lurking for far too long...Just picked up on this thread and must say this is an awesome build! I have the 1318 version in the pile and its been there a long time. This maybe just the boot I need to get building

Starbug said:

Been lurking for far too long...Just picked up on this thread and must say this is an awesome build! I have the 1318 version in the pile and its been there a long time. This maybe just the boot I need to get building

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When you dive into this one, make sure you have some extra stock balsa. Everything you cut needs to be exact and square. Having extra on hand will save aggravation on trying to make something not quite perfect fit. Hope you have a fin jig. If you don't, make one. Make ALL of your lines straight and dark.

I've not been posting but I've not been idle. I sprayed gray primer on the boosters. That was the oops. I sanded it (mostly) all off and reshot it with about 5 coats of Wally World flat white. It took that many coats to hide the gray dots. I've given them all a delicate sanding in prep for some red-orange. I hope to have that done by this weekend. I don't have to go to work again until Saturday.

It is gonna be purdy!