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Neil_W's half-baked design thread

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BABAR

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It occurs to me that if it's an engine, then it needs some sort of nozzle-y thing in the back. Sealed at both ends and separate from the main airframe (spaceframe?) doesn't make much sense, even to me.

I suppose the alternative could be that it's simply a power source positioned outside the main body, but I'm not sure that's the most logical explanation.
It could be a sensor unit or a communication unit, or a power supply mounted far out on the wingtip to protect the vehicle occupants from Theta Radiation (or the latest Google WiFi router)
 

jqavins

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This is just begging for some internal LEDs.
Ooh, yes yes yes! Multiple, unsynchronized color shifting LEDs* along the length. Place four or five of them along the length of the tube, with the inside frosted to blend them.


An RGB LED with the red, green, and blue elements ramping up and down at slightly different frequencies so you get a pseudo random shifting color. Dial in the limiting resistors to equalize the brightnesses so that when all three are on full the white is balanced. I made one years ago as a starting out Arduino exercise and proof of concept. It takes two layers of diffuser (white paper) to get the colors well blended, but one would be the surface of the tube.
 

jqavins

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I like it better without the ring, but I see at least one of the outer fins of a set breaking off on nearly every flight. The ring definitely majes them more secure.
 

mbeels

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I think I do like the version with the ring better, both are cool, and definitely, unmistakably "Wolverine". The ring sort of looks a bit like a fist.
 

neil_w

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I have played around with Moonshot quite a bit in OR. Building it as a two-stager turns out to be tricky.

If it's staged 18mm->18mm, then it really struggles to get off the pad. I just can't get it mass low enough, and it's a sure bet that the rocket would end up heavier than the OR model anyway. Given that the rocket has not one but two rings, it's possible it would stay straight even on a slow launch, but I just wouldn't feel good about it.

It could be two-staged, 24mm->18mm, although then I have annoying retention problems in the booster. That could send it up to about 1000' on a D12-0 -> C6-3, which would be a pretty nice flight although I may never find the booster.

If I revert back to a single stage, 18mm, then it shows up to something like 500+ feet on a Q-jet D. That's probably OK, this rocket wouldn't exactly be intended for performance anyway.

But I just don't feel conviction about any solution, so I'm going to hold off on it for now. It'll go right to the front of the build queue as soon as I make a decision. On to other things in the meantime.
 

BABAR

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Cluster the booster.

Main is still midline C6-0 ducted straight to the sustainer.

Secondary is a BT-5 motor tube with 13 motor, hidden “behind” the main (yeah, it will ruin the perfect symmetry, and you may need to run it a bit into the sustainer motor mount to give you more length). But at least from one side view it will be invisible, and if you paint it white it should be pretty well camouflaged in the other angles,

With a central C6 and auxiliary A10-3T (you want a delay for this to slow down before the A10-3T deploys the chute) you go from 8.82 to 10.82 total NS, but 2 more important factors

Nice initial power spike off the pad to get the stack moving

A recovery system for the booster. You pack a chute in the BT-5, as I said, you can use a longer tube than the current booster section and nest it into the sustainer motor mount. It just slides out at separation. Nose cone optional but perhaps advisable, chute might slide out from inertia when the booster kicks off the sustainer

In my experience (this is my most common technique for long gap black powered staging, since the long booster can’t successfully tumble), the slight asymmetric thrust from the off center auxiliary has negligible effect on flight path.


 

BABAR

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“Nesting “ the forward end of the auxilliary booster tube into the sustainer will also provide a more solid “link” between the two (you mentioned retainer problems, if the issue is lateral motion or “tilt” at the motor/sustainer junction, this fixes it in spades, but built right the nested tube section should easily slide straight out at separation, with booster chute deploying about 3 seconds later.)
 

BABAR

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I really like the two-stage idea, with the plunger popping out as the first stage. That would be fun to watch.



Perhaps, but fabricating that nose cone doesn't look trivial, and I bet it'd be a hit with the spectators.
Paper nose cone would be PERFECT for this. Easy to make, cheap, and SAFE, since if fecal turbine interaction occurs, it just collapses, leaving a much larger area to spread/disperse impact force (and therefore less lbs/square inch localized impact force. Analogy, given same mass and velocity which would you rather get hit by, a tennnis ball or a Phillips head screw driver pointy end first?)

Down side is you may want to keep a protective cover on it during transport to keep it from getting damaged (gee, kinda like a real needle cap, although for different reasons!)
 

jqavins

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I have played around with Moonshot quite a bit in OR. Building it as a two-stager turns out to be tricky.

If it's staged 18mm->18mm, then it really struggles to get off the pad.
So I take it this is the design you mentiomed in that other thread that needs to old B14-0 or new C5-0.
Analogy, given same mass and velocity which would you rather get hit by, a tennnis ball or a Phillips head screw driver pointy end first?
Closer analogy, the crumple zones in a car.
(gee, kinda like a real needle cap, although for different reasons!)
Oh, and make it look like a giant needle cap. Yeah, OK, more trouble than it's worth; just use some pipe. (But you coud use ½ or 1 oz fiberglass with a touch of pink pigment in the resin.)
 

lakeroadster

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Anybody made or observed a launch pad where, when the motor fires, it activates a mechanism (think crossbow) that shoots the rocket upward? That would minimize the motor's requirement to get the mass moving off the pad.
 

jqavins

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I've heard of one that went the opposite way. First a crossbow-like mechanism lets go and then the motor lights. Just add a small capacitor in parallel with the igniter to get the delay. You would have to make sure the igniter retaning plug is well secured. And I can't vouch for the veracity of the tail. It might require a longer rod, which might, sometimes at least, be all one needed in the first place.
 

jqavins

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Thinking of Moonshot, maybe someone's already said this, in current circumstances maybe it should be called Vaccine instead.
 

neil_w

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Thinking of Moonshot, maybe someone's already said this, in current circumstances maybe it should be called Vaccine instead.
Something like Vaccinator could work, but for now I still like the double-meaning of Moonshot.

Regarding above suggestions: I'm not really interested in doing something complex here to make the two-stage approach work. The interior construction is already more complex than I would like. I'll come back to this one.
 

BABAR

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Something like Vaccinator could work, but for now I still like the double-meaning of Moonshot.
Took me a moment, but I got it in the end.
 

neil_w

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A quick hack-and-slash from another thread:
1611419492597.png


Making this fly wouldn't be so easy due to asymmetry. The squeeze handle almost surely would be better off as two separate fins rather than one massive block.

Today I learned you can buy empty caulk tubes.
 

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I really like the Wolverine design, especially without the ring. A rear-ejection setup would remove the risk of snagging the chute.
 

jqavins

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Good luck getting anything short of mechanical fasteners to stick to that stuff.
The last time I noticed (not recently) the ones that inexpensive calk came in were like Pillsbury canisters, rolled cardboard with a glossy or foil outer layer, and a metal end cap crimped on. So carefully scoring and stripping the outer layer in key areas to take glue wouldn't be so hard. Getting the metal end past the RSO might be harder.
 

Nytrunner

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The last time I noticed (not recently) the ones that inexpensive calk came in were like Pillsbury canisters, rolled cardboard with a glossy or foil outer layer, and a metal end cap crimped on. So carefully scoring and stripping the outer layer in key areas to take glue wouldn't be so hard. Getting the metal end past the RSO might be harder.
Hmm, when I come across caulk tubes, they're usually superslick plastic, like cottage cheese or sour cream tubs.
 
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