Neil_W's half-baked design thread

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BABAR

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On the good side, assuming the balls are sealed, if you get a water landing it will float.
 

BABAR

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Kind of stole this from @Mx2 Fuel Pod rocket on the OddRocs section.



The balls to me just don’t really work as “plasma” containers or sources, to me those should be in cylinders or oblong containers, not balls or blobs.

But what about this?

An interesting version would be with the container rails made like cue sticks, the balls colored and numbered like billiard balls, maybe a triangular shaped “rack” as a type of ring fin, and the nose cone shaped like either the 8 ball or the cue ball

call it “Screwball in the Corner Pocket.”
 

Senior Space Cadet

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*Usually*, most radially symmetric airframes that would be turnable on a lathe can be constructed out of a combination of body tubes, paper shrouds, and nose cones. Paper tubes (talking LPR here) are usually the core because they are very strong, light, and can contain ejection charges. Almost anything can be wrapped around the core tube to build up a different shape.

Other examples than Lake's Tintin rocket:

Again, if you see anything specific that you have a question about, just ask.
Well, that is exactly how I made my design. I used a combination of nose cones, transitions and body tubes.
In an actual build, I would be greatly limited by what is available in the real world, though with more research and improved building skill, who knows.
Let me think about what I would really like to build, that I don't know how to design on Open Rocket, and then I'll ask some specific questions. You've opened up possibilities that I didn't know existed.
I'm not that into the whole sci-fi scene, so most of my rockets would lean toward having graceful lines, like a sailing ship.
 

jqavins

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LOL. OK, it's got a cool factor, but seriously the first thing I did upon seeing this is laugh.
Still need the expanded front section in my opinion. Four might work, if they’re spaced in pairs instead of evenly. Think an x-wing.
Hmm, expanded front section with all that other crap as well? I'll have to see how to work that in.
Yes. The more you do in the aft section the more plane the front looks. The expanded section is a good start up there.

Also, the balls out on the fins, in my opinion, detract from the idea of them as plasma cores. Cores should be in or along the core of the ship.
 

neil_w

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mbeels

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Also, the balls out on the fins, in my opinion, detract from the idea of them as plasma cores. Cores should be in or along the core of the ship.
Ok, they're not plasma cores. They're Takomak anti-matter plasma containment energy wells with a central ion chamber core.
 

neil_w

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Well, that is exactly how I made my design. I used a combination of nose cones, transitions and body tubes.
In an actual build, I would be greatly limited by what is available in the real world, though with more research and improved building skill, who knows.
I've one design (well, copied from some artwork I saw) based on nose cones:
1594643559253.png

For that particular OR model, I actually did trawl through the Apogee webpage to limit myself to actual available nose cones, just in case I ever wanted to build it. You're right that options are limited, although there are actually a lot of HPR nose cones out there; problem is they're often heavy and expensive to use for this purpose.

One challenge with these things is that it is best, if possible, to slot the tail cones for TTW mounting, since it is hard to surface-glue to many nose cone plastics. Slotting a cone like that is a bit challenging, compared to easy-peasy tube slotting.

3D printing is another option, and frees you from the restrictions of what's commercially available. And you can design the slots right in. Can be heavy, though, gotta be careful.
 

jqavins

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Ok, they're not plasma cores. They're Takomak anti-matter plasma containment energy wells with a central ion chamber core.
OK, whatever you call them, they're power generating modules that use plasma, and they're positioned far from the central part of the ship, on fins with very limited space for conduits that will bring plasma or cold gas out and and plasma, electricity, or whatever back in. The only reasons I can think of to go to that much trouble are 1) cooling (radiative to space which) is usually the last thing you's want for running the plasma core-of-a-power-system (because plasma needs to be hot to be plasma) or 2) reduction of the necessary radiation shielding on the hull (inverse square), which could be accomplished more easily by just keeping all the people up at the forward end of the skip. So plasma thingies on the fins just don't make sense, no matter what you call them.
 

neil_w

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Here's another variation that I don't like as much, but I might as well show it since I spent the time to do it.
1594662282136.png

Looking at it from the rear makes me think of a dried lotus pod:
1594662435419.png
 

jqavins

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1. I like five fin balls better than three, and I don't expect four would be any better.
2. Turning the fin ball axes from vertical (original) to horizontal (most recent) certainly make a big difference. I can see either one as better depending on how I tip my head or squint. I think overall I like the horizontal better, but it's very nearly a toss-up.
Looking at it from the rear makes me think of a dried lotus pod:
3. It made think of an office chair. But I still like it.
1594670322448.png
 

neil_w

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Been fiddling more with Plasma Dart decals, think I finally got the payload section to where I'm satisfied with it after just a small tweak:
1594848512621.png

An amusing realization dawned on me... the plasma pattern I ended up choosing is called "cell energy"... gives "Plasma Dart" a new level of meaning. :)

Which also means that I'm probably gonna stick with the red, unless I want to make it Vulcan green...

(although I do also like purple)
1594848714763.png
 

mbeels

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I'm definitely partial to that reddish-orange color. I had to go back and remind myself of where this left off, and what your tweak was. Looks like you carried the triangle shape over from the nose cone onto the body tube. (post #859)
 

neil_w

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I'm definitely partial to that reddish-orange color. I had to go back and remind myself of where this left off, and what your tweak was. Looks like you carried the triangle shape over from the nose cone onto the body tube. (post #859)
Correct! I think it fills in the front a bit better.
 

neil_w

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BTW I continue to struggle with launch lug location for this one, since there's not good mounting point anywhere near CG.

One thought I had was to put a standard 2" job in one of the main fin roots, and put a wire loop in between the two front transitions. That would stabilize it just long enough to get moving, but that front lug would be off the rod pretty quickly and then the rear lug would take over. Does that sound workable? I do *not* want any sort of visible lug uglying up the central core of the rocket.

What readily-available household wire would work as a lug? Would a large paper clip be suitably durable? I tend to think it would, even though it would likely get bent-up if it took a landing impact, although that's not a location where it typically would.
 

jqavins

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BTW I continue to struggle with launch lug location for this one, since there's not good mounting point anywhere near CG.

One thought I had was to put a standard 2" job in one of the main fin roots, and put a wire loop in between the two front transitions. That would stabilize it just long enough to get moving, but that front lug would be off the rod pretty quickly and then the rear lug would take over. Does that sound workable? I do *not* want any sort of visible lug uglying up the central core of the rocket.

What readily-available household wire would work as a lug? Would a large paper clip be suitably durable? I tend to think it would, even though it would likely get bent-up if it took a landing impact, although that's not a location where it typically would.
1. I've searched and never found a good reason for puting a launch lug at the CG, at the CP, or any other particular spot. The two inch lug down in the fin can is probably all you need.

2. Yes, a paper clip should do fine. That's what I used for Office Supplies.
 

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Two ideas

1. Easter Egg Dye?

2. @kuririn ’s apogee post requoted on last page post 1,171.
late to the game here, but I’m thinking some of those clear plastic Christmas ornaments ...paint goes on the inside, a little marble rolling around to spread some colors... might be an interesting option if the right size can be found
 

BABAR

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BTW I continue to struggle with launch lug location for this one, since there's not good mounting point anywhere near CG.

One thought I had was to put a standard 2" job in one of the main fin roots, and put a wire loop in between the two front transitions. That would stabilize it just long enough to get moving, but that front lug would be off the rod pretty quickly and then the rear lug would take over. Does that sound workable? I do *not* want any sort of visible lug uglying up the central core of the rocket.

What readily-available household wire would work as a lug? Would a large paper clip be suitably durable? I tend to think it would, even though it would likely get bent-up if it took a landing impact, although that's not a location where it typically would.
How about placing the lug directly in the dorsal fin/body tube joint, running the length of the fin? Not in the angle, but with the lug dead center between the fin and the tube. Probably could hide it with standard fillets, if not, small 1/16 balsa long wood panels on each side to hide the lug. Especially with the wood, this would be stronger than the normal fin joint, and just about completely hide the lug from site, while making it easily accessible. Yeah, it’s a bit remote from CG and CP, but given the long size unlikely to bind and since it is so far in the tail it stays on the rod longer, so helps stability a bit (makes EFFECTIVE rod length longer than a more standard placed lug,)

Interesting, Tim Van Milligan did a NAR report on launch lug drag. A Torus (basically a wire lug ring) turned out to be much higher drag than a standard lug. It was all done on a computer, so not sure how true that is in real life. On the other hand Open Rocket is the same.....

 

neil_w

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1. I've searched and never found a good reason for puting a launch lug at the CG, at the CP, or any other particular spot. The two inch lug down in the fin can is probably all you need.
We've had many discussions about this and I haven't seen a conclusive answer, only various people's intuition.

It would make me more comfortable to not only have a single lug way behind the CG. I'm going to at least try to see if I can get a wire loop up front. There's a bit of fabrication challenge to it (not the loop itself, but mounting it), but I'm always up for a gratuitous fabrication challenge to keep me busy.
 

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Anything you see substantial arguments about in rocketry doesn't really matter -- if it mattered nobody would be taking the wrong side (when was the last time you saw someone arguing CP should be ahead of CG?). The farther your lugs are behind CP and CG the more torque you've got on the lug, but unless you've got a pretty extreme rocket it won't make any difference.
 

mbeels

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Anything you see substantial arguments about in rocketry doesn't really matter -- if it mattered nobody would be taking the wrong side (when was the last time you saw someone arguing CP should be ahead of CG?). The farther your lugs are behind CP and CG the more torque you've got on the lug, but unless you've got a pretty extreme rocket it won't make any difference.
Good point, and I totally agree. When I was younger, I only ever put one launch lug at the fin root, not because I knew what I was doing, but I just copied other existing designs that did that. It worked fine. Launch lug position concerns seem to be a fairly recent invention.

I bet you wouldn't need the paperclip loop at front, but it certainly wouldn't hurt anything to have it there.
 

mbeels

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FWIW, here is a rocket I built before I knew about "over-stability" and before I could drive a car. It is 44" tall, BT-55, and I've launched it as a 1, 2, and 3 stage rocket. The first stage is BT-60, so I added a second 3/16" launch lug for clearance. I only used the 1/8" rod once, it wasn't enough.

P7170790_e.JPG
 

neil_w

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I shall consider. Feels like kind of a big rocket to have only the single lug in the back, but if I make it 3 or 4 inches long (or two 1-inchers a couple inches apart) maybe that's good enough. I'm going to see if I can cleanly implement a front-mounted wire loop; if not I'll just stick with the fin root.
 

jqavins

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If you want to mount the wire loop, here's what I did on Office Supplies; it worked quite well.
View attachment 391573
View attachment 391575

Mine have loops at both ends of the straight section, which is overkill for your situation. The straight section goes inside the body and is held in place by a coupler. Honestly, a patch of card stock would probably do, but there needs to be something covering it if you're using wood- or white glue that won't bond to the metal. This technique is one of only two things I took away from that build which I might use again on "normal" rockets.
 

mbeels

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If you want to mount the wire loop, here's what I did on Office Supplies; it worked quite well.
Yeah, that paperclip lug is a nice trick, it came out well.

I briefly thought about some kind of internal launch lug that ran inside one of the "plasma strakes", but that results in a hole in the front of the rocket, adds complication, and doesn't really help much. A small, clean wire loop is probably less noticeable than a launch rod exit hole.
 

BABAR

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Anything you see substantial arguments about in rocketry doesn't really matter -- if it mattered nobody would be taking the wrong side (when was the last time you saw someone arguing CP should be ahead of CG?). The farther your lugs are behind CP and CG the more torque you've got on the lug, but unless you've got a pretty extreme rocket it won't make any difference.
One practical matter where it makes a difference is individual versus club launches. The reason is related to the time spent on the pad waiting for “your turn” at club launches. My first experience with this was NSL 2019. It was (IMO) extremely well run, it was also the first “big” event I attended. Given location it logically catered to high power launches, but they did their best to humor us low power people with three banks of low power pads. There were still times when things got busy that 30 minute or more the rocket would spend on the pad. And the winds got bad, most the time acceptable but still high, at times launches were appropriately held or cancelled until winds died down.

I can’t speak for high power, but for low power with the rocket sitting on the pad buffeted by wind gusts, if lugs are not either AT the CP, or two lugs one distal and one proximal to CP, the leverage or moment arm between the Center or Pressure and the lug location puts a LOT of stress on the lug and may twist it off.
 

neil_w

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Some ideas sound better in your head than they end up looking in real (sim) life. Here's YAPCD*:
1595210137464.png

It's possible there's a better way to put these pieces together.

*Yet Another Plasma Core Design
 
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