Oops 2 Level 1 Cert Build

The following will be a build thread for my Oops 2, which will be my level 1 certification rocket.

It is a 3" diameter bird, 26.5" long, with 7 54mm tube fins. The nose and upper 8" of body tube separate from the bottom, in the standard zipperless design. The rear of the nose cone will be removed to provide more space for the laundry.









View attachment Oops 2 Level 1 Cert.ork

I finally got a hold of my shipment today, and started the build process.

First photo is of all (well most) the stuff splayed out on the table.

2nd photo: scoring the tubes with the ultra precise edge-of-paper-wrap method. Even using a pretty fresh exacto blade (not new, because I am all out of new blades,) it took forEVER to cut all those tube fins. My wrists still hurt.

3rd photo: dry fitting the rear assembly, minus tube fins. I am trying to decide what to do with the fore centering ring. Ideally, I'd grind it down to fit inside the tube coupler, but that sounds like a lot of work, and hard to get quite perfect. The other option would be to grind down half of it, so it nestles on top.
Suggestions?

4th photo: nose cone assembly. The nose cone is nearly as long as the rest of the rocket combined. The nose cone is 12.5" tall, whereas the rest is 14". Should make for a nice stubby looking rocket.




Next up is a whole ton of drilling. I need to make holes in a tube fin and the body tube and rear centering ring for the rear rail button. Anyone know how far I have to space the button off of the body tube for it to clear through the tube fin? I bought a few spacers along with my rail buttons.
Another hole must be drilled as far up on the rear 6" body tube as possible, through the coupler, for the fore rail button. 6" is under 1/4 of the way up the rocket, which seems rather low, but is as high as I can get.
Two more holes must be drilled in the rear centering ring for motor retention. I'll be using some mirror brackets to hold the motor in, along with hex cap bolts.
Another 2 holes will be drilled in the fore centering ring for a mini u-bolt for the recovery harness to attach to.
A final 2 holes will be drilled through the upper BT into the nose cone to hold it on. The tube is large enough I should be able to slide my hand in to tighten nuts. Any suggestion for what type of bolt to use for minimum drag?


All this drilling is going to be a real pain without a drill. I'm headed out to get some drill bits for my dremmel, and will have to trust in my steady hand and high rpm, for clean holes.

I don't have open rocket, at least I haven't loaded it since I did the Win7 Pro upgrade. What size MMT are you using. I hope it's at least a 38mm.

I did (almost, I forgot one hole,) all of the drilling today. I talked to the school machinist, but no go until I've got club status. Instead of quickly popping a few holes on the drill press, I got to try my hand at dremel drilling. The smallest bit was too small, so I wrapped a few layers of tape, and that seemed to work. The largest was too big, so we had to go with the medium bit, and enlarge from there.

Photo one: the whole lineup. All of the tubes cut to length.

Photo two: U bolt in the fore centering ring

Photo three: bolts holding the nosecone on to the fore section of body tube

Photo four: drilling into the side of the rear centering ring for the rear rail button

Handeman said:

I don't have open rocket, at least I haven't loaded it since I did the Win7 Pro upgrade. What size MMT are you using. I hope it's at least a 38mm.

Click to expand...

Yep, its a 9"x38mm MMT. I'll be testing on a G79SS, and then flying my cert on a H143SS.



Photo one: t nuts in the aft centering ring for motor retention

Photo two: starting the hole with an exacto knife. Without a drill press, and nothing to brace against, starting the hole well is really important.

Photo three: test fitting the rear centering ring, rail button, and accompanied tube fin. It all fits!

Started the gluing process today. I am to use mostly wood glue, but I've used epoxy on all of the hardware joints.

Photo one: fore centering ring ground down to nestle into the tube coupler

Photo two: motor retention using mirror brackets

Photo three: they were giving out play dough at school for some reason. Its perfect for keeping epoxy in check

Photo four: keeping epoxy in check inside the tube is a little bit tricky, but again, play dough saves the day

Looks a lot like Larry Brand's "H-Pod"...but different.

Are you going to reinforce the tube fins? I used half doublers and epoxy on my tuber. Solid.

o1d_dude said:

Looks a lot like Larry Brand's "H-Pod"...but different.

Click to expand...

Thats the basis of the design. Just with my own slightly more practical and durable spin on it (no offense Larry Brand). I just need to figure out how to attach the recovery harness to the nose cone. I'm cutting the bottom of the nose cone off, so I'll need to do something. I could go for Larry's approach and glue a dowel in there. Any other suggestions?

o1d_dude said:

Are you going to reinforce the tube fins? I used half doublers and epoxy on my tuber. Solid.

Click to expand...

I was considering it, but I'm not sure I will. The tube I am using is quite thick, so I think it should fair alright. The H won't push it past 664fps, so I don't think fin flutter should be too much of a problem. I will however use Larry's masking tape on the leading edge trick.

For my Madcow squat, a similar size rocket (29" tall, 4" diameter) I cut the nosecone base off, then I roughed up the top area with a lot of 100 grit sandpaper. To attach the recovery system, I put a 1/4-20 T-nut in a 54mm bulkhead, and used a lot of JB weld to attach it. Then my dad put a large amount of a type of construction adhesive in (I forgot the name, but it was suposed to stick well to the plastic). To attach the recovery system, I used a length of threaded rod, put an eye nut on one end, added nose weight with fender washers, followed by a hex nut to hold it together. Then I tied the shock cord to the harness, reached in and screwed it in.

(Note, my avatar is of my squat drag racing Larry Brand's tubefinned squat)

I finally got all those damn tube fins glued on! Here is the rocket, almost completely built. It still needs some finishing, and paint of course.

Instead of wrapping masking tape over the leading edge or soaking it in CA (flying in sub zero weather makes that one a no-no,) I have tried embedding a bit of wood glue in each edge. I just wipe a thin film of glue over the leading and trailing edges of the tube fins, and try to smush it in to the fibers. With a thick paint job, hopefully delaminating won't be a problem.

As for the nosecone problem, I think I have found my solution. I'm going to use copious amounts of epoxy putty to attach a quicklink as far up the nose cone as I can reach my hand. That way I can easily replace the recovery harness should it be damaged, or add nose weight if stability proves a problem. It will also keep my options open if I chose to add electronics later.

Lentamental said:

Instead of wrapping masking tape over the leading edge or soaking it in CA (flying in sub zero weather makes that one a no-no,) I have tried embedding a bit of wood glue in each edge. I just wipe a thin film of glue over the leading and trailing edges of the tube fins, and try to smush it in to the fibers. With a thick paint job, hopefully delaminating won't be a problem.

Click to expand...

If you want the wood glue to soak in like thin CA, make up a 50/50 mixture of wood glue and water, and add several drops of liquid soap or dish washing detergent. It will soak in very fast and still dry hard. This is what train models use to glue the gravel ballast on the train tracks.

Just made an ACE run, and picked up all of my painting supplies. I went entirely for Rustoleum. No cheap paint this time. Depending on how the weather treats me, I'm planning to go the whole 9 yards, with two coats of (Rustoleum Painters Touch Ultra Cover 2x) primer, with 250 grit sanding, and then 400 grit sanding. Then will go a layer of yellow, followed by proper masking, and the top coat of black. I also got one of those rattle-can guns to try out.

Speaking of the weather, do you have any last advice for painting in sub-freezing weather?

My dorm has a heated bike storage shed that I leave my rockets in to set. We get all laid out in the shed, shake up the can, get the rocket masked, and all that prep stuff. Then I dash out the door and quickly lay on a few sprays of paint before running back inside. There we hold the rocket in front of the heating vent, wait a minute or so, and run outside to repeat the process. It takes a while, but it seems to work.

I heard one person recommend letting the cans sit in warm water, to keep it from spitting too much. Anything else you can think of?

Finally got it all finished a week or so ago, but haven't taken photos of the completed project. It looks pretty amazing if I do say so myself.

Here are photos before the black coat went on.
I'll get photos of the final rocket before too long.

I finally got it all done, and had a fantastic launch with CRMRC. First flight on a G79-8ss had a bit of a bonus delay, but went without a hitch otherwise. Then I loaded it back up with a H143-6ss, and roared my way to level 1. It was a long walk on a 36" chute, but I got the rocket back unharmed.

Congratulating you on your L1! Well done, Tube Man!

I didn't realize you built it with 7 fins. D'oh!

o1d_dude said:

I didn't realize you built it with 7 fins. D'oh!

Click to expand...

Its a bit trickier to align, but the drag is greatly reduced, and at least with the stubby tubers, in my opinion, 7 fins looks much sleeker.

I'm going to have to build one of these.

Congrats on the L1!


Braden

I highly recommend it. The stubby tube finned rockets are a lot of fun to fly and incredibly strong. You can toss that thing in the back of the car and not worry about it. If I'd fiberglassed the outside edges of the tubes, I'm pretty sure I wouldn't even need a parachute...

Lentamental said:

I highly recommend it. The stubby tube finned rockets are a lot of fun to fly and incredibly strong. You can toss that thing in the back of the car and not worry about it. If I'd fiberglassed the outside edges of the tubes, I'm pretty sure I wouldn't even need a parachute...

Click to expand...

This one is three inches in diameter right?


Braden

Yep, 3"x27" with 7x 54mm tube fins. They needed little balsa shims to fit perfectly.

Well done on your L1.

I'm impressed you had the confidence to fly it on a G before going for the H.

Bones

Well I had two Gs and only one H (as per ordering restrictions) and I really didn't want to have make another order of a single highpower motor, due to the insane shipping fees. I'd rather wreck the rocket on a G and have to fix it, the test on the 2nd G, than test on the H, have it fail, and have to order motors again.

Maybe in the summer, with a kit, I would have felt more comfortable launching the cert motor right away, but dealing with thermal expansion, chuffing, uncertain delay times, and my first reloadable motor ever, I wanted to make sure I had it down right first. Most important for that first flight was getting tips from the other people there on assembling a HPR motor (even if it was a simple CTI) as I had never done that before.

Congrats on the L1!:clap:

Lentamental said:

Well I had two Gs and only one H (as per ordering restrictions) and I really didn't want to have make another order of a single highpower motor, due to the insane shipping fees. I'd rather wreck the rocket on a G and have to fix it, the test on the 2nd G, than test on the H, have it fail, and have to order motors again.

Maybe in the summer, with a kit, I would have felt more comfortable launching the cert motor right away, but dealing with thermal expansion, chuffing, uncertain delay times, and my first reloadable motor ever, I wanted to make sure I had it down right first. Most important for that first flight was getting tips from the other people there on assembling a HPR motor (even if it was a simple CTI) as I had never done that before.

Click to expand...

RMS 101, eh?

I neglected to mention how nice the black and yellow color scheme turned out. Bet it really stands out on the snow.

I'm in the process of masking off my Bottle Bat 2.6 and have gone through half a roll of tape just to get the insides of the tubes a different color from the outsides. Lotta work, innit?

Bone Daddy said:

Well done on your L1.

I'm impressed you had the confidence to fly it on a G before going for the H.

Bones

Click to expand...

Not only that, he got his L1 with a scratch-built bird.

o1d_dude said:

Lotta work, innit?

Click to expand...

Oh my, so very much. Keeping the insides of the tube clean was impossible. No matter how I pressed the tape in, it always seemed to make some air bubbles. In retrospect I should have painted the bottom black instead of yellow, because after two flights on smoky sams, I honestly couldn't tell whether I had painted it black or yellow. Even attacking it with a wet sponge only got it back to a grimy half black half yellow.

Thank you all for you compliments. I need all the courage I can muster to push on through level 2, 3, and then, in theory, for my senior engineering project, into space with a rockoon. Call me over ambitious if you like, but as they say, "If you shoot for the moon and miss, you'll still be among the stars."

I love those smokey sams as well and find that you need to have some of those Clorox wipes to get the residue off....

Lentamental said:

.

Photo two: U bolt in the fore centering ring

Click to expand...

Hey, where'd you get that cute little u-bolt?

I know, its adorable, isn't it? It was from some hardware for steel cable. It was part of a set used to make a loop end with steel cable, and looked too perfect to pass up. The one thing you have to be careful of is that its a very tight fit to connect the quicklink to. I can only get it in at a very precise angle.

Lentamental said:

I know, its adorable, isn't it? It was from some hardware for steel cable. It was part of a set used to make a loop end with steel cable, and looked too perfect to pass up. The one thing you have to be careful of is that its a very tight fit to connect the quicklink to. I can only get it in at a very precise angle.

Click to expand...

Sometimes adorable is high maintenance.