More Half-Baked Designs Thread

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How do you get the CG and CP outside the rocket?
It’s a display error on the 3D view, I think it’s a compatibility issue with the v22 beta release on my machine. I don’t have the coding knowledge to fix it, nor do I really want to make a GitHub account to report it and the occasional stability problems I’ve been experiencing.
 
Thanks to a rocket name posted here, this may just have to be my next build.
1663867096240.png
I'm thinking three inch body tube and thick rounded fins. The little people astronaut is to scale. It's short, so it'll need nose weight, but I'm guessing not too much. I may have it separate completely so the "capsule" can come down on it's own; if I can figure out a good way to get a streamer attached to the top of the nose cone so the capsule comes down right side up then I'll definitely have to do that. And I do have a germ of an idea how to do it.
 
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Thanks to a rocket name posted here, this may just have to be my next build.
View attachment 538642
I'm thinking three inch body tube and thick rounded fins. The little people astronaut is to scale. It's short, so it'll need nose weight, but I'm guessing not too much. I may have it separate completely so the "capsule" can come down on it's own; if I can figure out a good way to get a streamer attached to the top of the nose cone so the capsule comes down right side up then I'll definitely have to do that. And I do have a germ of an idea how to do it.

That would be awesome as a low altitude rocket, and a few of the astro's coming down on parachutes.
 
Thanks to a rocket name posted here, this may just have to be my next build.
View attachment 538642
I'm thinking three inch body tube and thick rounded fins. The little people astronaut is to scale. It's short, so it'll need nose weight, but I'm guessing not too much. I may have it separate completely so the "capsule" can come down on it's own; if I can figure out a good way to get a streamer attached to the top of the nose cone so the capsule comes down right side up then I'll definitely have to do that. And I do have a germ of an idea how to do it.
Had to be done:
1663879481300.png
 
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Of course, I'd like to use one of the classic wooden little people. But, if I'm willing to give up that detail, there is this:
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Or this:
1663880867903.png
 
Thanks to a rocket name posted here, this may just have to be my next build.
View attachment 538642
I'm thinking three inch body tube and thick rounded fins. The little people astronaut is to scale. It's short, so it'll need nose weight, but I'm guessing not too much. I may have it separate completely so the "capsule" can come down on it's own; if I can figure out a good way to get a streamer attached to the top of the nose cone so the capsule comes down right side up then I'll definitely have to do that. And I do have a germ of an idea how to do it.
Maybe, uh, adjust the fin shape a little or something?

https://www.navytimes.com/news/your-navy/2019/05/14/the-navys-probe-into-sky-penis/
 
I've been fooling around with highly-optimized minimum-diameter rockets that make use of very long delays. Most of them are questionable for one reason or another but I think this is a whole other level. Lots of half-baked things on this one. It makes my other OR creations look almost practical. More a question of "what would it take?" than "is it possible?" I'm starting to suspect that the full 15-second delay setting wasn't really intended to be used, not with LPR single-stagers anyway.

I ended up calling it complete once the ideal delay time was halfway between the 12- and 15-second settings.

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Also, try changing from a truncated cone tailcone to a truncated elliptical or ogive. A longer tailcone might help, and the smallest back end you can manage. Is that as small as the motor diameter? Is it as small as the nozzle, with the tailcone friction fit to the body tube and serving as the motor retainer?
 
Have you considered if Mr. Krushnik will attend the maiden flight of your rocket?

View attachment 542126
I’ve elected to shelf this one. I realized that I set the fins to 1mm thickness somehow and correcting them to 1/8 inch sapped a lot of delay time. The durability of the tailcone was also a concern, if I ever end up going for the full 15 it’ll be with a complex configuration I think.

This is the half-baked thread, after all.
 
So I tried to make a Buzz Bomb / V-1 with the engine in the top pod where it was supposed to be... That did not work (even without the wings to move the CP forward and make things even less stable -- although maybe they would have counted the spin)...

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Has anyone done a P38 Lightning inspired rocket?

Just a quick mock-up in OR to figure out where CP is more or less on this oddroc. Seems like it might be feasible. I have not done a traction engine before and this has a bit of that... Not sure if I can jam a chute in that short front section. Maybe it should be rear ejection...?

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That would be cool. I'd be a little worried with rear ejection getting tangled up with the horizontal stabilizer. Seems safer to get the laundry out the front, challenging though that might be.
 
Has anyone done a P38 Lightening inspired rocket?

Just a quick mock-up in OR to figure out where CP is more or less on this oddroc. Seems like it might be feasible. I have not done a traction engine before and this has a bit of that... Not sure if I can jam a chute in that short front section. Maybe it should be rear ejection...?

View attachment 556713

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It'll be interesting to see how this turns out. I've done a P-40 Warhawk inspired rocket, an F-4U Corsair one (that was almost stable) and a B-29 inspired one, all based on Pringles cans as body tubes. But they're all more traditional rocket in style with features from their inspirations and require 3D printed components.
 
Thanks everyone for the earlier feedback on the P-38. Lots of iteration on that one but it is flying and looks pretty cool (I need to finish my 3rd build of one with the propellers in place to see how it flies with them)!

Anyway, posted in its own thread so as not to drag down this one with tons of P-38 posts... (most people have probably seen it but just in case here is the link):
https://www.rocketryforum.com/threa...5-3d-printed-parts-plywood-wings-fins.177167/
 
Next questionable / half-baked project -- do you guys think that the Snark can be built and made stable without additional fins?

Other than the huge forward-placed wings, the biggest challenge I see is the relatively small and singular vertical fin (although placed far back on the model).
1679142632388.jpeg

I was wondering what if I used the boosters as the only engines -- maybe a pair of 24mm engines in those boosters. How do mid-body motors compare to traction motors or standard rear motors?

I played around with OR w/ a BT-80 main body and BT-55 boosters. Might need to downscale to BT-60 + BT-50. That tube fin is larger than the intake would be but I was thinking of making the intake connect through to boat tail exhaust so it should have a stabilizing effect.
1679142608789.png

I know that Apogee has a Snarky model and have seen some other builds that are hybrids of the Snark with something else.
 
Robert,

Referring to your V-1, here is what has worked for me with a pusher airplane with a high thrust line in relation to the wing. If the thrust line of the motor is parallel to the wing, the airplane will dive under application of throttle with the dive increasing with addition of more throttle. To fix that, you point the thrustline down through the CG of the wing and you no longer have trim changes with throttle change. I've included a picture of a tailless model seaplane I've used this on.

The parallel to the wing thrust line might have worked on the V-1 because it's thrust to weight ratio and acceleration is probably a lot less than a model rocket. They were also launched off a compressed air powered ramp or dropped from an He-111, which means the engine wasn't used for high acceleration launching but for cruise. It would probably be simplist to put the motor on the centerline of the fuselage with the wing on and launch it fairly noseheavy.

Something more interesting for you to try is a ZELL (ZEro Length Launch) F-104. You can see in the pictures that the thrustline goes through the CG of the wing. If you got around to your BT-80 F-104, that would be an impressive vehicle! Probably have to launch it at 45° and have the launch lugs on the bottom of the booster and under the nose.

Richard
 

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Robert,

Referring to your V-1, here is what has worked for me with a pusher airplane with a high thrust line in relation to the wing. If the thrust line of the motor is parallel to the wing, the airplane will dive under application of throttle with the dive increasing with addition of more throttle. To fix that, you point the thrustline down through the CG of the wing and you no longer have trim changes with throttle change. I've included a picture of a tailless model seaplane I've used this on.

The parallel to the wing thrust line might have worked on the V-1 because it's thrust to weight ratio and acceleration is probably a lot less than a model rocket. They were also launched off a compressed air powered ramp or dropped from an He-111, which means the engine wasn't used for high acceleration launching but for cruise. It would probably be simplist to put the motor on the centerline of the fuselage with the wing on and launch it fairly noseheavy.

Something more interesting for you to try is a ZELL (ZEro Length Launch) F-104. You can see in the pictures that the thrustline goes through the CG of the wing. If you got around to your BT-80 F-104, that would be an impressive vehicle! Probably have to launch it at 45° and have the launch lugs on the bottom of the booster and under the nose.

Richard
Thanks - yes, came to better understand this with the P-38 model. I have not revisited the V-1 but I worry that the motor would need to be canted too much to make the offset motor work and still look prototypical. I suppose if the motor mount is larger than the engine I can hide the engine cant some. Maybe I just need to do a token booster motor in the top motor space a bit like the NASA style F-104 I made (but that would require a larger main engine).
 
Make a ZELL F-104 into a 2 stager: First stage is using the booster to get it off the pad. Second stage is the tail motor lit at booster burnout. Some other ZELL subjects to consider are the Firebee, Mace, and Matador.

My favorite Firebees are the early retro versions. They recovered by parachute. There are 72nd and 48th scale plastic kits available to scale from.

It would give you whole new category of thrust lines to evaluate.
 

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Make a ZELL F-104 into a 2 stager: First stage is using the booster to get it off the pad. Second stage is the tail motor lit at booster burnout. Some other ZELL subjects to consider are the Firebee, Mace, and Matador.

My favorite Firebees are the early retro versions. They recovered by parachute. There are 72nd and 48th scale plastic kits available to scale from.

It would give you whole new category of thrust lines to evaluate.
That is a really interesting model -- would need to be almost all 3D printed which is difficult to make cost effective but definitely interesting looking!
 
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