More Half-Baked Designs Thread

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jqavins

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OK, Neil, two can play at this game. Or more than two. I have one half baked idea, drawn up in Visio, that I started taking about in another thread which was about what to do with two really big, heavy tubes. If I do it it'll probably just be BT60s. After this, everyone (except Neil ;)) is invited to play.
Crosseyed.jpg
 

neil_w

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For what it's worth I really like this concept... As a variation, consider joining the two tubes somewhere below the nose cone, yield a payload section of sorts up top.

I was playing around with some related ideas but nothing with two parallel tubes going all the way to the business end.
 

dhbarr

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The similar neighborhood I'm playing with is a two-fin ( yup! ) design with side-by-side g65's. Really looking forward to seeing how you work through the various challenges if you go that way.
 

jqavins

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I realized while lying in bed this morning that screwed up the geometry of the nose cone. The side view should be this:
upload_2019-10-2_7-33-43.png

But then, if I do the merge lower to create a payload section, I could do it by expanding the tubes at the same time a merging them to make one of those payload bays that's larger than the tube below. There could be a section of full diameter round tube, or not. Below, the left column is the front view, with and without the full size tube section; middle is the side views; right is the series of cross sections moving down the transition.
upload_2019-10-2_7-53-37.png
I'm now liking the large with extra payload length version. I also could print multiple versions and make them swapable.
 

MClark

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There was a rocket at BALLS years ago with two tubes similar to yours, however it had two nose cones.
It was painted black and white and was called "Spy vs. Spy" like the Mad Magazine comic.
 

mbeels

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Interesting idea. Making that nose cone would be pretty tricky. Another idea (just to throw more half-baked ideas out there) would be to have the top of the nose cone be a line, instead of a point. So the top of the cone would be a wedge, instead of a point.
 

BABAR

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However you do the nose cone(if you go single cone inserted into both tubes), shoulders need to be short and “loose”. That way if one of the cluster doesn’t ignite, ejection charge of the successful motor will be able to blow the large cone, is doesn’t “hang” on the other tube.
 

neil_w

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However you do the nose cone(if you go single cone inserted into both tubes), shoulders need to be short and “loose”. That way if one of the cluster doesn’t ignite, ejection charge of the successful motor will be able to blow the large cone, is doesn’t “hang” on the other tube.
I wonder if the shoulder shouldn't extend all the way around both halves. Perhaps omitting shoulder in certain areas (the two ends?) would reduce the chance of getting hung up.

My guess is it would require testing to determine the ideal shoulder geometry.
 

jqavins

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There was a rocket at BALLS years ago with two tubes similar to yours, however it had two nose cones.
It was painted black and white and was called "Spy vs. Spy" like the Mad Magazine comic.
I saw a photo once here on the forum of someone's pair of rockets, almost but not quite matching in design, one mostly black with some white and the other mostly white with some black; together they were Spy vs. Spy, but flew separately. Perfect for a drag race if you ask me.

Interesting idea. Making that nose cone would be pretty tricky.
Construction of the two tube to one transition, in whatever form, will by 3D printing.
Another idea (just to throw more half-baked ideas out there) would be to have the top of the nose cone be a line, instead of a point. So the top of the cone would be a wedge, instead of a point.
Interesting. I'll give it some thought.

However you do the nose cone(if you go single cone inserted into both tubes), shoulders need to be short and “loose”. That way if one of the cluster doesn’t ignite, ejection charge of the successful motor will be able to blow the large cone, is doesn’t “hang” on the other tube.
I wonder if the shoulder shouldn't extend all the way around both halves. Perhaps omitting shoulder in certain areas (the two ends?) would reduce the chance of getting hung up.
I had the same thought on the nose shoulder. Even if both sides' engines light, their ejection charges won't be dead-on simultaneous, so the nose will want to tip and will be in danger of jamming. A short shoulder with a slightly rounded bottom edge is at least part of the answer. Graphite dry lube probably is too. I guess a partial shoulder might be as well, but I'll need a little time to get my head around that. Yet another possibility is to put vent holes between the two halves to allow the pressure to equalize. (But there isn't much room for vents. I'm showing the tubes tangent, which is what I intend, but I didn't show the fillets I'd surely add. The fillet depth to each side gives a little room for vents, but not much.)
---------------------------------------
This thread isn't supposed to be just my stuff. Let's see what's half done in other people's brain ovens.
 

mbeels

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Yet another possibility is to put vent holes between the two halves to allow the pressure to equalize.

I like the idea of a fairly long vent slot between the two tubes. Similar to what the Trident uses to duct the ejection charge.
 

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I like the idea of a fairly long vent slot between the two tubes. Similar to what the Trident uses to duct the ejection charge.
Would have to be below parachute storage. Otherwise chutes might get "confused " and jam up in the slot.
 

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This is well outside your original plan, but it would be really interesting to have a double rocket like this that separated on the way up, say 2-3 seconds before normal apogee. That would take electronics and a bunch more work to make happen. Just throwing it out there as a 37.5% baked idea.
 

jqavins

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I do indeed. Id' be happy if this thread becomes like that one, sims not required.

Well, this one's even less than half baked. And actually it's two. Y'know the design with a ringtail internally tangent to the body tube? Or a single tube fin attached on the opposite side from it's centerline, if you'd rather call it that. What about applying two of those rings, with interlocking slots where they pass each other? That'd look nifty, wouldn't it?
upload_2019-10-2_12-7-14.png

And what about one of these tangent ringtails but with the ring actually a Möbius strip? Oh, sure, the twisting of the ring would certainly play hob with its aerodynamics. That's OK, fix that by making the arrangement symmetrical by using two like the picture above. (Yeah, I did say "less than half baked".)
---------------------------------------------
Come on, somebody else!
 
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neil_w

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Well, this one's even less than half baked. And actually it's two. Y'know the design with a ringtail internally tangent to the body tube? Or a single tube fin attached on the opposite side from it's centerline, if you'd rather call it that. What about applying two of those rings, with interlocking slots where they pass each other? That'd look nifty, wouldn't it?
Yes it would!
new_ring1.png

Painting would be a challenge.
That could be cool. When I look at an idea like that, I then think: what could you do with the fin shape and/or paint job to really accentuate the weird fin angles? And then my standard response to myself is: I have no idea. :)
 

jqavins

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OK, I stand bested.

That could be cool. When I look at an idea like that, I then think: what could you do with the fin shape and/or paint job to really accentuate the weird fin angles? And then my standard response to myself is: I have no idea. :)
That's why I made the fins on each pair different colors with a third one underneath. So rather than "I have no idea" I can say "I've only got one idea."
 
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I do indeed. Id' be happy if this thread becomes like that one, sims not required.

Well, this one's even less than half baked. And actually it's two. Y'know the design with a ringtail internally tangent to the body tube? Or a single tube fin attached on the opposite side from it's centerline, if you'd rather call it that. What about applying two of those rings, with interlocking slots where they pass each other? That'd look nifty, wouldn't it?
View attachment 394764

And what about one of these tangent ringtails but with the ring actually a Möbius strip? Oh, sure, the twisting of the ring would certainly play hob with its aerodynamics. That's OK, fix that by making the arrangement symmetrical by using two like the picture above. (Yeah, I did say "less than half baked".)
---------------------------------------------
Come on, somebody else!
Great designing minds think alike. Jim Flis' Celtic Thunder:
1016190707.jpg
 

neil_w

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That's why I made the fins on each pair different colors with a third one underneath. So rather than "I have no idea" I can say "I've only got one idea."
Another thought: Use three colors for the fins, have each coplanar pair be the same color. I don't know if that would be good or not...

I'd also be interested to see ring segments bridging between... the uh... let's say "each pair of far-apart fins" (I have no terminology for this.) Maybe about 2/3 the way up the fins.
 

mbeels

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Great designing minds think alike. Jim Flis' Celtic Thunder

Ah, I knew that reminded me of something, but I couldn't remember what. It is the Celtic Thunder I was thinking of.

Joe, I do like your Triple V design. I think that fin concept could also be used with your twin tube rocket design.
 

jqavins

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I had Celtic Thunder somewhere in the back of my mind and couldn't remember the name or source. And I like that design. The one I offered, with two rings rather than three, gives a sort of figure eight (or infinity) look that the other doesn't, and I like in a different way.

Thanks for all the kind words and ideas on my half (or less) baked ideas. Now come on, folks, let's have someone else's!
 
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boatgeek

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I've mentioned elsewhere that I'm running for school board here. When the election is over in 3 weeks, I need to collect all of my yard signs. And then they either go into the trash or something useful happens with them. So what can be done to make them into a rocket? I'll need a motor mount, but otherwise everything is going to be planar surfaces, and none longer than 24" (signs are 18x24). I have a one sign for another race that's got the reinforcing running along the 24" direction, but most are along the 18".

I'm thinking something like a downscale of my Dimetrodon rocket, maybe 2" square. It should fly OK on F motors on a 29mm motor mount, though I could also go 24mm and use CTI 2 and 3-grain motors. Any suggestions for fins or structure would be appreciated. No paint, just cut up signs from several campaigns. I'd probably have to glue/screw some stringers in the square corners to hold everything in place.
 

jqavins

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What kind(s) of glue work well that plastic? If there's one that holds firmly you could use - dang, what's the term? - alternating notches like a squared off dovetail joint. With the non-trivial thickness of those signs as compared to the 2" side that should be somewhat stiff. With the centering rings that also serve as ribs down low and a nose pyramid shoulder that also acts as a rib up top I don't think you'd need any other corner reinforcement.

There are two ideas I've pondered before for the fins on a square rocket. First is you could place them on the centers of the sides, with through the wall tabs that are only as deep as the signs are thick, maybe two or three separate tabs in separate slots. Second is to form the fins by widening the bottom portion of each side in one direction, with the squared off dovetail notches becoming slots in that area to receive the tabs from the unwidened edge of its neighbor. I'd go with plain square fins to go along with the rocket's overall blocky look.

Make sure at least one panel shows off your own name from the original printing!

And let's hear it for rocketry in the schools! Good luck at the poles.
 

boatgeek

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What kind(s) of glue work well that plastic? If there's one that holds firmly you could use - dang, what's the term? - alternating notches like a squared off dovetail joint. With the non-trivial thickness of those signs as compared to the 2" side that should be somewhat stiff. With the centering rings that also serve as ribs down low and a nose pyramid shoulder that also acts as a rib up top I don't think you'd need any other corner reinforcement.

There are two ideas I've pondered before for the fins on a square rocket. First is you could place them on the centers of the sides, with through the wall tabs that are only as deep as the signs are thick, maybe two or three separate tabs in separate slots. Second is to form the fins by widening the bottom portion of each side in one direction, with the squared off dovetail notches becoming slots in that area to receive the tabs from the unwidened edge of its neighbor. I'd go with plain square fins to go along with the rocket's overall blocky look.

Make sure at least one panel shows off your own name from the original printing!

And let's hear it for rocketry in the schools! Good luck at the poles.

I gotta do some more research on glue. One issue is that the printing is like a vinyl decal, so it peels off pretty easily.

One of my flyers has a picture of the students in the rocketry club holding a TARC rocket that took 3rd at nationals a few years back and their last HPR project (3" hand-rolled carbon fiber, 13,500 feet, Mach 1.6).
 

boatgeek

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It seems I have ordered some parts for this one from 802high, which I didn't entirely mean to do at this time. So now I have to build it. Which means I have to decide on all the little details. Design and build thread to follow, I guess.

Oh noes! You have to build a rocket?! :)
 
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