Neil_W's half-baked design thread

[BABAR]

I'm not especially a LOTR fan so I'll leave the decor details to others. If anyone wants the ORK file so they can do all up, let me know.

Realistically, for my version, I would call it "Ring Warrior" and come up with new names for the others. As I stared at it yesterday, I realized that conceptually it has a *lot* of similarity to Alcubierre, which makes it a bit less appealing as a possible build (hate to repeat myself any more than necessary). But I still like it and may fiddle with it some more.

How committed are you to Open Rocket? How about some geometric cross section rockets, triangles or squares?
Nice thing is, the nose cones are dirt cheap, easily crafted from card stock. Centering triangles or squares from foam board. Rocket sides are cardstock, no spirals to fill. Fins? Can still use balsa, but hotel key cards or card stock also possible.

 

[neil_w]

How committed are you to Open Rocket? How about some geometric cross section rockets, triangles or squares?
Nice thing is, the nose cones are dirt cheap, easily crafted from card stock. Centering triangles or squares from foam board. Rocket sides are cardstock, no spirals to fill. Fins? Can still use balsa, but hotel key cards or card stock also possible.

My problem is I can't visualize them easily, and I really need to. My CAD chops are not adequate for me to do that sort of thing.

Edit: I should say I can fake square airframes, not nose pyramids though. And I did mock this one up a while back:

(I'd still kind of like to do that one. Haven't figured out an adequately precise way to make the body)

 

[BABAR]

Haven't figured out an adequately precise way to make the body)

Picture matting board?
Score the inner surface to create perfect folds, leaves you with only one seam.

 

[neil_w]

Wouldn't that be really heavy?

I was thinking thin balsa cladding, but there would need to be some good precise supports underneath. Admittedly I haven't thought about it too seriously recently, for various reasons.

My big brainstorm was to use pink Plasti-Dip for the eraser.

 

[mbeels]

My big brainstorm was to use pink Plasti-Dip for the eraser.

Oh, that would work. Maybe even cushion the landing a tiny bit . You could also use aluminum tape for the metal banding.

 

[jqavins]

Turn a balsa piece in a lathe to make the groves in the metal band, then press the aluminun tape into the grooves as you wrap it around.

 

[BABAR]

Wouldn't that be really heavy?

I was thinking thin balsa cladding, but there would need to be some good precise supports underneath. Admittedly I haven't thought about it too seriously recently, for various reasons.

My big brainstorm was to use pink Plasti-Dip for the eraser.

If it sized out right, use the cap from a can of pink spray paint

 

[neil_w]

I am utterly smitten with the design of the newly announced Lotus Evija, particularly the tail:

I don't know if I can take inspiration from that for a design, but I'm gonna think about it. Frankly, the whole car is not too far away from being a sci-fi rocket.

Don't think I'll be picking one up too soon, though, at a price tag of $2.1 million.

 

[neil_w]

This fin can has some potentially interesting (?) ideas in it.

 

[jqavins]

Yeah, a few interesting ideas. Maybe too many all at once. Or maybe not, if you can get the paint scheme right.

 

[neil_w]

Maybe too many all at once.

Almost certainly. Needs plenty of exploration and refinement.

 

[BABAR]

This fin can has some potentially interesting (?) ideas in it.
View attachment 392295
View attachment 392296
View attachment 392297

With minimal modification could be made into a non gap two stage

 

[boatgeek]

My problem is I can't visualize them easily, and I really need to. My CAD chops are not adequate for me to do that sort of thing.

Edit: I should say I can fake square airframes, not nose pyramids though. And I did mock this one up a while back:

(I'd still kind of like to do that one. Haven't figured out an adequately precise way to make the body)

I was thinking foam core board. Could still be scored with a ruler and then broken. It probably wouldn't be light enough to fly on BP motors, and I'm not sure where you stand on composites.

 

[neil_w]

Yeah, in a sort of Solar Flare sort of way. Actually, now that I think about it, *quite* similar to the Solar Flare.

I think I'm not crazy about the fin shape in those pictures. I think like the idea of the ring with thick parts between paired fins, and then thinner parts spanning fin pairs. Need to try it with a wing-style arrangement.

As always, doing funky-shaped rings built up from segments in OR is a tedious process. So trying out different variations is slow going.

 

[neil_w]

I was thinking foam core board. Could still be scored with a ruler and then broken. It probably wouldn't be light enough to fly on BP motors, and I'm not sure where you stand on composites.

I'm fine with single-use motors and motor eject. Single-use F motors start to get a little pricey for my taste for routine flying (with the notable exceptions of the F44 and F67).

I still think balsa cladding (say, 1/16") would be feasible, given some supports at the corners. OR shows a 24" airframe made from BT55 clad in 1/16" balsa at 2 oz, which should keep the finished model in a very reasonable weight range (fine for E motors). Others would probably visualize this thing in larger sizes.

I've also debated inside my head whether it would be best off with shoe white square fins, in homage to the Estes Skywriter, or go for maximum pencilness with clear plastic. In the latter case, it would be fun to really go all out making the thing as pencil-y as possible. I like @jqavins ' idea of wrapping foil tape around a form for the metal eraser holder (does that thing have a proper name?)

 

[jqavins]

[T]he metal eraser holder (does that thing have a proper name?)

I'd call it a ferrule.

 

[neil_w]

I'd call it a ferrule.

...and you would be correct. Thank you sir.

Could almost cannibalize one of these things for parts...

 

[boatgeek]

I'm fine with single-use motors and motor eject. Single-use F motors start to get a little pricey for my taste for routine flying (with the notable exceptions of the F44 and F67).

I still think balsa cladding (say, 1/16") would be feasible, given some supports at the corners. OR shows a 24" airframe made from BT55 clad in 1/16" balsa at 2 oz, which should keep the finished model in a very reasonable weight range (fine for E motors). Others would probably visualize this thing in larger sizes.

I've also debated inside my head whether it would be best off with shoe white square fins, in homage to the Estes Skywriter, or go for maximum pencilness with clear plastic. In the latter case, it would be fun to really go all out making the thing as pencil-y as possible. I like @jqavins ' idea of wrapping foil tape around a form for the metal eraser holder (does that thing have a proper name?)

That thickness of balsa would definitely get it done. I did visualize in larger sizes, but a 24mm motor mount/stuffer tube with 1/4" foam core panels (approx. 37mm across the flats) would fit pretty nicely with a BT-55 body tube for the nose and eraser. That might be light enough to fly on E motors, but if not an F44 would do nicely. I don't know if there's a conical nose cone readily available for BT-55. If I get my act together on other projects, I may try to give that a build sometime this winter.

I personally would go maximum pencil-ness, but YMMV, etc. etc.

 

[mbeels]

I don't know if there's a conical nose cone readily available for BT-55.

Estes has a 3-pack of BT-55 cones that includes a conical one.

 

[neil_w]

I had previously had the semi-clever idea of taking a BT60 conical nose cone, cutting it off at the shoulder, and cutting/sanding it down like so:


Using a balsa cone is key, because (a) you can sand it, and (b) you get nice natural wood-grain. Only need some CA go finish it.

Sanding it accurately and then Cutting those little parabolic pieces to fit and getting the whole thing to really fit tightly would be no small challenge. Now that I think of it, I'd probably move the couple down on the BT; having the seam so close to the point would call too much attention to it.

 

[jqavins]

You've noticed how, when a pencil is sharpened, the paint-to-wood line shows a crenelated patters to to the cone coming further down the corners than it does the flats. The hexagon-to-circle transition could be done with a 3D printed part.

EDIT: Oops, ninja'd. Using a balsa nose cone would give the natural wood grain, as you say, and 3D printing would make shaping it precisely a whole lot easier.

Incidentally, the curves are hyperbolic, not parabolic.

EDIT Again: I've got it. Make the hexagonal body prism. Get or make a balsa nose cone that fits the corner-to-corner diameter so that it hangs over on the faces, with the shoulder fitting the face-to-face diameter. (Here's the aha! bit.) Attach a piece of very thin sheet metal* to a face of the body and put the cone in place.Then you can sand the cone down to the face without sanding through the metal. In effect, the body itself becomes the jig that assures a perfect fit to itself.

* There's stuff called shim stock that's thinner than anything usually called sheet, only a few time foil thickness.

 

[neil_w]

Incidentally, the curves are hyperbolic, not parabolic.

Right you are! I had to go review my conic sections again. Been a loooooooooooong time.

EDIT Again: I've got it. Make the hexagonal body prism. Get or make a balsa nose cone that fits the corner-to-corner diameter so that it hangs over on the faces, with the shoulder fitting the face-to-face diameter. (Here's the aha! bit.) Attach a piece of very thin sheet metal* to a face of the body and put the cone in place.Then you can sand the cone down to the face without sanding through the metal. In effect, the body itself becomes the jig that assures a perfect fit to itself.

That is a darned good idea. Would be the first thing I try, to be sure.

In the meantime, I went and rechecked my sizing, and it is a BT55 + 1/32" thick cladding to achieve nearly perfect match with a BT60 nose cone. Perhaps in my next parts order I'll get one of those cones and give a whack at sanding it down. That's a good winter project.

I think even 1/32" balsa would work fine, given that I would paper it or something for extra strength and to seal it.

Got an idea for accurately aligning and supporting the cladding at the corners?

Could use strips of basswood, but they'd need to be applied dead straight and perfectly positioned in order to support both pieces. Maybe not so bad, but it worries me. Even building a test piece a few inches long won't tell me if it's gonna work at 24".

Maybe if I use 1/32" plywood I won't need the supports?

 

[jqavins]

Maybe use a cradle, 3D printed so you get great precision. A bottom piece of just the right width, then sides at 60° up, and they don't need perfectly precise lengths. Lay in three pieces and your center tube. Once that glue is hard you can rotate it and add on more side at a time.

Come to think of it, you probably need two cradles, one at each end, since you probably can't get one piece printed that's long enough. But you could design in a feature that lets you use a pair of straight things (like aluminum angle or tube) to align them.

 

[BABAR]

Right you are! I had to go review my conic sections again. Been a loooooooooooong time.


That is a darned good idea. Would be the first thing I try, to be sure.

In the meantime, I went and rechecked my sizing, and it is a BT55 + 1/32" thick cladding to achieve nearly perfect match with a BT60 nose cone. Perhaps in my next parts order I'll get one of those cones and give a whack at sanding it down. That's a good winter project.

I think even 1/32" balsa would work fine, given that I would paper it or something for extra strength and to seal it.

Got an idea for accurately aligning and supporting the cladding at the corners?
View attachment 392337
Could use strips of basswood, but they'd need to be applied dead straight and perfectly positioned in order to support both pieces. Maybe not so bad, but it worries me. Even building a test piece a few inches long won't tell me if it's gonna work at 24".

Maybe if I use 1/32" plywood I won't need the supports?

Any chance your launch lug could be internal, between the ring and the hexagon?
Paper soda straws are cheap on amazon, and they will have easily handle to up to 3/16 rod

 

[jqavins]

Ooh! You stated you'd be papering the airframe after assembling it. How about preprinting the paper with the classic pencil yellow color and even the markings on one side?

Essentially it's structural papering and a full body wrap in one. That'd certainly make finishing a heck of a lot easier.

 

[BABAR]

Sounds like a StickerShock job.

Big box stores have rolls of adhesive paper for lining drawers and cabinets. Since you are papering such a large surface, might work to just build the rocket with sanded but otherwise raw balsa, using a single piece of adhesive backed paper to wrap and provide a smooth base, and then do a vinyl wrap.

 

[neil_w]

Any chance your launch lug could be internal, between the ring and the hexagon?
Paper soda straws are cheap on amazon, and they will have easily handle to up to 3/16 rod

Looks like it won't fit, there's very little room in there.

Ooh! You stated you'd be papering the airframe after assembling it. How about preprinting the paper with the classic pencil yellow color and even the markings on one side?

Hmm, not impossible... would need to be at least one seam in the middle. If I made the seam at the location where the body tube breaks, then I'd only have a single seam to worry about.

What I would worry about is laying down label paper accurately. You only get one shot with it. Then on the nose cone I would need to sand-trim it, which would leave very white edges.... hmm I would need to think hard about that.

There are many stupid technical challenges on this build... which I am not in any way committed to at the moment. Still, it might be fun to experiment with various little bits of it, to see if they'll work.

Sounds like a StickerShock job.

Maybe. Trimming the crenellated edge around the point would be a challenge. That's the area where painting would be easier. Masking would be a pain, but wouldn't need to be perfect the first time, could keep working with it until I get it right.

 

[neil_w]

This is an interesting challenge. I am experimenting.


Even I an reproduce this, how do I attach fins to it, clear or otherwise?

 

[Nytrunner]

Talk to the modeler's good friend Joe-Bob Weld

 

[neil_w]

Talk to the modeler's good friend Joe-Bob Weld

'Twould be a mess, gluing to the bumpy surface. Dontcha think?