Mandalorian Rocket

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lakeroadster

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BABAR

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And now for a couple pictures of the (hopefully) final design.
View attachment 453746
View attachment 453747
And now for a couple pictures of the (hopefully) final design.
View attachment 453746
View attachment 453747
25BB2577-C58C-4A02-9326-C4BBA2B89AA1.jpeg

okay, this probably says more about me, but here goes,

the complete rocket is really cool, but can you please paint the tube some other color or put on some crazy decal or paint scheme that sort of hides that long cylindrical thing that comes out between his legs? It just looks kind of, well, wrong.
 

lakeroadster

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View attachment 454349
okay, this probably says more about me, but here goes,

the complete rocket is really cool, but can you please paint the tube some other color or put on some crazy decal or paint scheme that sort of hides that long cylindrical thing that comes out between his legs? It just looks kind of, well, wrong.
Some cotton balls for display purposes? :dontknow: (to simulate exhaust plume.....)
 

Funkworks

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... It just looks kind of, well, wrong.
I see this as a prototype and at this stage, anything goes!

... including the idea of making it big enough to actually put two motors in the jetpack, but to start I have settled with a Mandalorian wearing a jetpack figure with the rocket tube up through the legs and body ....
Also: heads pops up so this one is not a human. 🤖
 

lakeroadster

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RockSim model isn't a perfect representation, but with the added fins around the ring fin (modeled as a cylinder in RockSim) I should have "good" margin for stability. The swingtest is a must I think. I will try it both with just the conical ring fin and with added external fins.
View attachment 453737
View attachment 453738
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Did you try shortening the tube to the point that he is standing on the fin can, and then adding ballast at his head?
 

hermanjc

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View attachment 454349
okay, this probably says more about me, but here goes,

the complete rocket is really cool, but can you please paint the tube some other color or put on some crazy decal or paint scheme that sort of hides that long cylindrical thing that comes out between his legs? It just looks kind of, well, wrong.
Painted the tube gray, and I do plan to add a "THIS IS THE WAY" decal.

Did you try shortening the tube to the point that he is standing on the fin can, and then adding ballast at his head?
Completed a swing test tonight with the longer tube and it was stable. Total weight with a D12 is at 200g. I would have had to add significantly more "helmet weight" if I wanted to shorten the tube.
IMG_20210309_235100166.jpgIMG_20210309_235109724.jpg
IMG_20210309_235127028.jpgIMG_20210309_235141298.jpg
 

lakeroadster

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lakeroadster

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Painted the tube gray, and I do plan to add a "THIS IS THE WAY" decal.


Completed a swing test tonight with the longer tube and it was stable. Total weight with a D12 is at 200g. I would have had to add significantly more "helmet weight" if I wanted to shorten the tube.
View attachment 454681View attachment 454682
View attachment 454683View attachment 454684
One thing to be mindful of is the drag of the conical ring makes the rocket more stable than the simulation indicates.

My mindsim thinks you could cut the distance from his feet to the ring in half and it would still be a good flyer, without adding any weight. Might be something to try after he already has a number of flights under his belt.
 

hermanjc

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Maiden flight today. Flew slow and low on a C5-3. Good second flight too, but chute took too long to open and suffered some tube bending above the ring fin. But I'll take this as a win. He can be repaired, next flight will be on a D12.
IMG_20210320_160458814.jpgIMG_20210320_160505002.jpg
 

lakeroadster

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BABAR

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Very cool.

what’s the mass of the ring assembly itself?

I was wondering if the next rendition might work with a larger ring (like the diameter of the current edge of the outer fins), ditch the outside fins, use 3 or 4 internal dual purpose fins/spokes, and ditch the angle on the ring and the outer fins. I think such a construct would provide greater stability (good), possible less drag by ditching the angle on the ring (also good), but not sure of effect on mass of the fin can unit compared to current.
 

hermanjc

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Very cool.

what’s the mass of the ring assembly itself?

I was wondering if the next rendition might work with a larger ring (like the diameter of the current edge of the outer fins), ditch the outside fins, use 3 or 4 internal dual purpose fins/spokes, and ditch the angle on the ring and the outer fins. I think such a construct would provide greater stability (good), possible less drag by ditching the angle on the ring (also good), but not sure of effect on mass of the fin can unit compared to current.
Given that I had to cut out a section of body tube just above the existing conical ring, I took you up on your suggestion @BABAR. I have increased the outside diameter to 9 inches, which required me to print the ring in 5 parts (my printer has a max build footprint of 5.5in x 5.5in) Rocksim model shows some margin for stability, and I will swing test with the ring temporarily in place to confirm stability. Mass of the new ring is 60g, while the old one was about 40g, so it did go up some.
9in_ring_update.JPG
Mando_RockSim_2D_Side1_short.JPGMando_RockSim3D_short.JPG
IMG_20210325_092626813.jpgIMG_20210325_092640382.jpg
IMG_20210325_092753739.jpg
 

BABAR

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Given that I had to cut out a section of body tube just above the existing conical ring, I took you up on your suggestion @BABAR. I have increased the outside diameter to 9 inches, which required me to print the ring in 5 parts (my printer has a max build footprint of 5.5in x 5.5in) Rocksim model shows some margin for stability, and I will swing test with the ring temporarily in place to confirm stability. Mass of the new ring is 60g, while the old one was about 40g, so it did go up some.
View attachment 457053
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First, still looks great.

second, comparing this to previous version sim, your mass is as you say up 20 grams, but your length is down 6 inches. Looks great either way, just wondering why the change?

Stability dropped below 1 caliber.

At 200 grams currently, you have plenty of room before you max out the lift capacity of your D12.

it may fly fine the way it is now, a stable swing test would certainly encouraging.

potential issues with the shorter tube:

recovery gear space will be at a premium, even tighter than before.
If stability really IS marginal, I suspect you can easily get back to what you had before by restoring 2 or 3 inches of tube length, I don’t think you will need to go back to the full 20” previously. This will both increase your stability and but you a little more room for wadding and chute. It won’t cost much in extra mass, 5-10 grams maybe?


does losing the canted ring for a straight ring cost you or gain you in the stability market? I am guessing the canted ring adds more drag and provides more stability than straight, but i am guessing.

your design gives me an idea for a dual TYPE of recovery for a rocket, eject the ring fin and motor mount tube with a windowed ring for horizontal spin, but keep it connected as one piece with a snap swivel (to allow to spin) with the body of the rocket (in this case the actual BODY of the Mandalorian!) which comes down under a chute. Biggest problem I see is unlikely the snap swivel can keep up with the spin on the ring (it’s gonna whirl like the proverbial Dervish!) and will likely tangle up the cord
 
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