Shear Insanity: a build thread

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jqavins

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soft kitty soundtrack.
Reminds me of the (completely irrelevant) time many years ago that I turned on the radio and just heard a sort of rumbling noise. Sort of multiple rumblings, and shifting over time. My wife and I were listening in profound puzzlement, and just figured that radio was busticated when the announcer came on (perfectly clear) and said "That was the fugue for eleven cats purring." We didn't stop laughing for a considerable time.
 

Daddyisabar

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To increase CP anxiety the oddroc builder could add Greebles such as cut or stretched conduits, pipes, cables, or other protruding broken equipment or leaking fluids/steam. My inner rocket scientist would scream like C3-PO: "It's a nightmare!" Strap on explosives so the range officer can hit the self destruct button! Abort the abomination! Run to the Bunker, Steiner is not going to save you. Ripley's gonna get you! Fear is the mind killer, but it sure is exciting!

Sometimes I yern to launch on the kiddie pad. Just a nice safe Alpha on a A8 3...Dreams.
 

neil_w

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LAUNCH LUGS, PART 1

That's right, you get not one but *two* posts about launch lugs. You're welcome.

I eventually decided to do two smallish (3/4") lugs. The easiest side of the rocket to put them on would be in line with one of the canted fins. Because that's not possible, I went with the next best option and put the rear lug alongside the fin, and the front lug will go... well, in line with that one.

The most "normal" part of the canted fin is at the center of its root, so that's where the lug shall go. I put it on a 1/32" balsa standoff, just to ensure clearance with all the body tube segments.
lug - 1.jpeg
The pencil line on the fin is a trace of the lug, so I can be sure to apply glue in the correct spot, e.g.:
lug - 2.jpeg
Then the lug was pressed into place.
lug - 3.jpeg
Fillets will follow. Gotta let this one dry before I do the front lug, since that will involve threading a rod through for alignment.
 

neil_w

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LAUNCH LUGS, PART 2

After attaching a piece of 1/32" standoff to the second lug, I positioned it at the center of the next segment, using Mr. AA to align it with the first lug:
lug - 4.jpeg
This will put the forward lug a bit further back than I wanted, but moving it to the next segment would have been too far forward. It'll be fine.

Looking at it in person it's incredibly difficult to judge alignment. The canted segments really play tricks on the eyes.
lug - 5.jpeg
Sighting from the back, it looks good.
lug - 6.jpeg
I am incredibly proud of myself for having nailed the camera position for this picture. It's hard to do when everything is hand-held. This picture does once again show how weird and deceiving the angles are.

Finally I went to do the launch rod test, and... my launch rod is MIA. Looked for a good long time, absolutely can't find it. Hmm. So a piece of wooden dowel filled in.
lug - 7.jpeg
Fit perfectly, seems properly aligned with the longitudinal axis of the rocket. A bit of still-wet Q&T fillet on the rear lug is visible in the picture.

Lugs are finished.
 

neil_w

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FINISHING UP THE NOSE ASSEMBLY

After some measurements and fiddling in OR I decided the nose needed just a *bit* more weight. So I got a bit more lead shot and the piece of dowel that goes in the pre-drilled hole in the nose.
nose section - 1.jpeg
I put in the shot with a bit of epoxy, then epoxied in the dowel, jamming it in as far as it would go to ensure the shot was tightly held in. By chance, it ended up almost flush.
nose section - 2.jpeg
The nose + weight ended up weighing a bit over an ounce, heavier than I would like but not really much heavier than a typical plastic nose cone.

I then glued the nose into the top segment, using alignment marks I had previously made to ensure it went in the correct position. Despite the marks, I check and re-checked the position about 1000 times before finalizing the attachment.
nose section - 3.jpeg
Some CWF around the base of the nose smoothed out the joint with the body, and the assembly is done.
nose section - 4.jpeg
And assembly is now complete. Final weight: 3.7 oz, minus parachute and shock cord. Should do well on 24mm D and E motors.
completed assembly.jpeg
Never mind the apparent curve of the airframe in the above pic; that's lens distortion. The whole thing is indeed, um, "straight", and I use that word advisedly.

Looking at that picture, I now realize that I put the lugs on the wrong side of the rocket; that is the side that I wanted to put the logo decal. Never even considered that until just now, oh well. Speaking of which, I need to start figuring out the paint scheme, although who knows when next paint opportunity will arise. The rocket really could use a coat of filler/primer, but I don't think I have it in me to sand all the nooks and crannies of this one.
 

lakeroadster

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FINISHING UP THE NOSE ASSEMBLY

After some measurements and fiddling in OR I decided the nose needed just a *bit* more weight. So I got a bit more lead shot and the piece of dowel that goes in the pre-drilled hole in the nose.
View attachment 500088
I put in the shot with a bit of epoxy, then epoxied in the dowel, jamming it in as far as it would go to ensure the shot was tightly held in. By chance, it ended up almost flush.
View attachment 500089
The nose + weight ended up weighing a bit over an ounce, heavier than I would like but not really much heavier than a typical plastic nose cone.

I then glued the nose into the top segment, using alignment marks I had previously made to ensure it went in the correct position. Despite the marks, I check and re-checked the position about 1000 times before finalizing the attachment.
View attachment 500090
Some CWF around the base of the nose smoothed out the joint with the body, and the assembly is done.
View attachment 500091
And assembly is now complete. Final weight: 3.7 oz, minus parachute and shock cord. Should do well on 24mm D and E motors.
View attachment 500092
Never mind the apparent curve of the airframe in the above pic; that's lens distortion. The whole thing is indeed, um, "straight", and I use that word advisedly.

Looking at that picture, I now realize that I put the lugs on the wrong side of the rocket; that is the side that I wanted to put the logo decal. Never even considered that until just now, oh well. Speaking of which, I need to start figuring out the paint scheme, although who knows when next paint opportunity will arise. The rocket really could use a coat of filler/primer, but I don't think I have it in me to sand all the nooks and crannies of this one.

Have you considered something like a lightening bolt as a decal? It kind of lends itself to the design.
 

Daddyisabar

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FINISHING UP THE NOSE ASSEMBLY

After some measurements and fiddling in OR I decided the nose needed just a *bit* more weight. So I got a bit more lead shot and the piece of dowel that goes in the pre-drilled hole in the nose.
View attachment 500088
I put in the shot with a bit of epoxy, then epoxied in the dowel, jamming it in as far as it would go to ensure the shot was tightly held in. By chance, it ended up almost flush.
View attachment 500089
The nose + weight ended up weighing a bit over an ounce, heavier than I would like but not really much heavier than a typical plastic nose cone.

I then glued the nose into the top segment, using alignment marks I had previously made to ensure it went in the correct position. Despite the marks, I check and re-checked the position about 1000 times before finalizing the attachment.
View attachment 500090
Some CWF around the base of the nose smoothed out the joint with the body, and the assembly is done.
View attachment 500091
And assembly is now complete. Final weight: 3.7 oz, minus parachute and shock cord. Should do well on 24mm D and E motors.
View attachment 500092
Never mind the apparent curve of the airframe in the above pic; that's lens distortion. The whole thing is indeed, um, "straight", and I use that word advisedly.

Looking at that picture, I now realize that I put the lugs on the wrong side of the rocket; that is the side that I wanted to put the logo decal. Never even considered that until just now, oh well. Speaking of which, I need to start figuring out the paint scheme, although who knows when next paint opportunity will arise. The rocket really could use a coat of filler/primer, but I don't think I have it in me to sand all the nooks and crannies of this one.
I would paint/decal it with some scheme that would make it look as if it was cut up. Off set images, stripes or letters on decals. Reminds me of freshly cut, unbaked cinnamon roll dough. Ummm... Yummy Cinnabon! On the cut ends show the internals.

Warning: The following suggestions might get you banned for the use of excessive morbidity. CUT THAT MEAT! Just like the Peyton Manning commercial. With a pointed nose cone you could do a chopped up "buttered finger" as shown in Tim Burton's ALLICE. Chopped snake or worm. I am currently working on a rocket named Join or Die, a famous chopped up snake image from Ben Franklin. Good thing the old dudes like 18th century American history or it just might be a banning.
 

Daddyisabar

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"Out West; RSO" :oops: I thought it was "The Wild West"?
Wyoming bound for the real Wild Wild West. Heaven's Gate. The local law man is present and made a wager it will fly straight. Living in the 80's, heading for the 90's...the 1890's!...In the Wild Wild West! The Gay 90's! (A historical term referring to the optimism, happiness and fimancial booms of the 1890's. Included so as to not trigger semantically sensitive moderns.)
 

neil_w

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Hope to have some paint scheme details to share soon. Or should it be a surprise?

In the meantime, I have observed that with all the body segments glued together with centering rings, this thing is a *tank*. And with all of its super-dragginess, it would be a good candidate to load up with E motors (I'm thinking Q-jet E26-4). Should I be concerned that a 16" long BT50 (core tube) is a bit small for an E ejection charge? Or is it not something to worry about?
 

mbeels

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Should I be concerned that a 16" long BT50 (core tube) is a bit small for an E ejection charge? Or is it not something to worry about?

I would bet that is fine. I've flow Es and Fs in a dual deploy rocket with a lower booster section smaller than that. I think that the important thing would be to have a shock cord long enough so that it can dissipate the energy of the nose cone flying off. You wouldn't want the nose cone yanking too hard, or springing back against the rocket. My favorite method is to put small loops of masking tape on a Kevlar shock cord, it helps keep things neat, and when they tear, it dissipates a lot of energy.
 

DigBaddy

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Hope to have some paint scheme details to share soon. Or should it be a surprise?

In the meantime, I have observed that with all the body segments glued together with centering rings, this thing is a *tank*. And with all of its super-dragginess, it would be a good candidate to load up with E motors (I'm thinking Q-jet E26-4). Should I be concerned that a 16" long BT50 (core tube) is a bit small for an E ejection charge? Or is it not something to worry about?

E26 doesn't have much punch out of the gate, D22 has more. E20 may be a better choice.
 

neil_w

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My favorite method is to put small loops of masking tape on a Kevlar shock cord, it helps keep things neat, and when they tear, it dissipates a lot of energy.
I've seen this done in high-powered rockets... in an LPR scenario I can never tell how strong to make the tape. Too strong you've just made a super-short shock cord. :) Also have never seen the tape loops applied to an elastic shock cord, somehow doesn't seem like a good idea.
E26 doesn't have much punch out of the gate, D22 has more. E20 may be a better choice.
This rocket will be only about 4 oz dry, I suspect an E26 will have no trouble getting it moving. I have some E20s handy as well if needed. :)
 

Bruiser

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I think the shock cord should handle it. I like using kevlar coming out of the tube then I transition to elastic. I will fold the elastic over on itself a few times and put a wrap of masking tape around the folds. I do that a few times to help dissipate energy like mbeels wrote

-Bob

You ninja'd me :)
 

Bruiser

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I use blue painter's tape and just wrap the folds so the tape sticks to itself

-Bob
 

mbeels

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I've seen this done in high-powered rockets... in an LPR scenario I can never tell how strong to make the tape. Too strong you've just made a super-short shock cord. :) Also have never seen the tape loops applied to an elastic shock cord, somehow doesn't seem like a good idea.

Yeah, probably you can just pack it up as normal, and the rocket would be fine. A long shock cord helps as well, but this is getting packed into BT50, which doesn't leave much room!
 

neil_w

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Crochet your long kevlar shock cord and neatly pack into small tube.
Tried that once unsuccessfully on Starship Avalon, but in that case I had crocheted 1/8" elastic. It kind of jammed up and didn't pull clean on ejection. When I had tested it over and over outside the rocket, it pulled cleanly and easily every time. Maybe Kevlar would be more likely to pull clean, being smoother.
 
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