More Half-Baked Designs Thread

[jqavins]

I'd gladly look for options; I assumed 3D printed for the dual requirements of keeping it hollow and looking for the exact right aspect ratio. I dimensioned the nose cone and other parts from a NAR graphic, and I don't want to deviate from it.

I could also look inro custom machined balsa with a BT60 size core hole.

 

[Greg Furtman]

My next project, after the Triple-V, will be a return to this. When I found the moving box with lots of my rocket stuff a week ago or so, I found the booster from this with a rebuild motor tube that I don't remember doing. I kept the sustainer for single stage use (not that I've ever actually flown it) and found that quite a while ago, so I could be ready for another ground test pretty quickly. Come to think of it, with the Triple-V going in slow motion, I might just get back to this before finishing that.

@jqavins I looked at your long running build and was pleased to see it is a Terrier-Orion sounding rocket. Two years ago I was lucky enough to spend a week at NASA Wallops with 5 students at RockOn 2018. We built an instrument package (along with 30 other teams) that was launched into space on a Terrier-Orion.

 

[mbeels]

I'm not aware of a readily available long conic BT60 nose in plastic.

Ah, I was thinking of the Estes Black Brandt nose cone, but that is BT55.

How long is that nose cone? Erockets has a balsa conical BT80 nose cone, but it is 6.5" and doesn't look long enough. Their BT-60 conical cone looks closer to the right proportions.

If I were doing it, I'd be inclined to go rear eject and eliminate the BT-60 stuffer tube in favor of a longer motor mount tube (is that 24mm?). Then your recovery space is between the BT50 and BT-80, which is quite generous. For the nose cone, I'm not entirely sure, but I like the idea of a BT-50 conical cone plus transition, as neil_w suggested.

 

[mbeels]

@jqavins I looked at your long running build and was pleased to see it is a Terrier-Orion sounding rocket. Two years ago I was lucky enough to spend a week at NASA Wallops with 5 students at RockOn 2018. We built an instrument package (along with 30 other teams) that was launched into space on a Terrier-Orion.

I'd love to read more details about this, do you have any more photos or payload specifics that you could post here on TRF somewhere?

 

[jqavins]

@jqavins I looked at your long running build and was pleased to see it is a Terrier-Orion sounding rocket. Two years ago I was lucky enough to spend a week at NASA Wallops with 5 students at RockOn 2018. We built an instrument package (along with 30 other teams) that was launched into space on a Terrier-Orion.

I read about that program years ago. I tried to talk my daughter into being interested so that I could go with her, but she's go no interest at all beyond going along on launches. I tried - for the hobby and a token effort for that - but she is just immune to the rocket bug.

Marten: yeah, if I go rear eject I'd certainly ditch the BT60. And the nose cone is just under 14". A short BT60 (standard eject) or BT50 (rear eject) nose cone would still have to have that 5.35:1 aspect ratio precisely. Could I settle for 5:1? Welll, I suppose so, but I don't want to. Would a scale modeler settle?

Rear eject with a custom 5.35:1 cone and a card stock shroud might be the answer. And then I might be back to 3D printing the cone. And I might need nose weight, but it'd still be lighter than 3D printed all the way up. Lots to consider.

 

[BABAR]

Dare I say... Rear eject???

Go you one better, SEGMENTAL recovery. Modification of Estes Wacky Wiggler or Odd’l Rockets BreakAway

Each fin is attached to a 1/4 diameter through-the-wall body tube segment

Segments are linked into motor mount pod, maybe by rods attached to nose cone, but there are lots of ways to skin this cat.

At ejection, nose cone kicks forward, pulling the fixation rods, releasing each of the four fins.

Kevlar thread attachments between all parts, nose cone, pod, four fin-tube units. If you do a standard upward flight profile, you HAVE to keep parts together or you will never find them all. It actually works amazingly well, although this will be a little different with fin units separating laterally rather than BreakAway separating longitudinally.

Alternative is CATO recovery, where you launch on a Zero delay motor and all parts separate about 25 feet above the pad (very dramatic, especially if RSO isn’t in on it.). Finding 6 parts that separate 25 feet off the pad is doable (paint them bright colors, including the motor mount and the INSIDE of the fin units.). Finding them when separation occurs 100 feet or more above the pad, more of a challenge.

Fin units (tethered or not) will fall with the tube side DOWN, as that will be the lowest drag, so the fins are unlikely to be point of first contact when rocket hits Terra all-too-Firma

So either Segmental or CATO recovery is a way of recovery delicate fins intact (although you have to basically DeConstruct the rocket in flight, it’s still kind of fun)

 

[BABAR]

Nose cone is a true cone. Make it out of paper. (I.e., Roll your own!). This will make it much lighter, cheaper, less likely to break. Extend your rear eject motor mount tube far up into the nose cone itself, and put your “nose” weight on the forward end of the motor pod. This is a GREAT trick for rear eject pop pod gliders, you can eject most of your nose weight with the pop pod.

 

[BABAR]

Heck, make the nose cone AND the body from card stock

 

[jqavins]

Go you one better, SEGMENTAL recovery. Modification of Estes Wacky Wiggler or Odd’l Rockets BreakAway...

Alternative is CATO recovery...

I have a BreakAway in my build pile, and your CATO recovery is a fun idea I've been considering trying out for some time now. But not this time. Feel free to take the basic design and run with it in any direction you like.

Nose cone is a true cone. Make it out of paper...

Not a bad idea. Building rockets from parts is more interesting to me than fabricating parts. When I need to make parts I'd rather use a laser cutter, 3D printer, or some other CNC (i.e. nearly goof proof) method than try to do anything freehand, because I suck at anything freehand. But that doesn't mean I'll refuse to do it if it's the best way to solve a given problem, and maybe this time it is. At least I can laser cut the card stock to roll it from.

Heck, make the nose cone AND the body from card stock.

See above. No. It's designed around BT80, and BT80 it will be.

 

[BABAR]

. And I could make up some basswood ply just as easily as balsa ply. And paper it.

I like this. Wondering if it might be worth it to paper the balsa ply sheets BEFORE cutting them out, might help the off axis ply (perpendicular to leading edge) to hold together better before you “ply” the fin sections to each other, even better would be to ply the balsa before you cut it, but I don’t know what your equipment is. Might be tough to cut plywood bass, at least with an exacto knife.

 

[jqavins]

My equipment is the laser cutter at my nearest maker space. So yes the plan, no matter what ply construction, paper, or both, is to make it up as pieces of stock and then go cut.

 

[jqavins]

Speaking of tube fins, what are the interesting, weird design possibilities of tube canards?

 

[neil_w]

I think the challenge with tube canards is that the really pull CP forward.

 

[BABAR]

I think the challenge with tube canards is that the really pull CP forward.

@rcktman actually built and flew this

https://barc775.files.wordpress.com/2015/05/ring-hawk-plans-002.pdf
Although I can’t find his post on it. Essentially a sliding ring, works as a fin during boost and a canard after burn string breaks and ring slide forward to canard position. I still struggle with the physics of it, how does a ring shaped glider figure out which way is “up”, but it sure looks cool.

 

[Nytrunner]

Very interesting design.

My thoughts are that the roll orientation is immaterial due to the symmetric profile, and the main factors are angle of attack and CG CP balance (maybe CL in its case). The vehicle receives the same lift no matter its roll position, fea ity still works "down" and geberal air density decreases "up".

Ingenius design

 

[mbeels]

@rcktman actually built and flew this

https://barc775.files.wordpress.com/2015/05/ring-hawk-plans-002.pdf
Although I can’t find his post on it. Essentially a sliding ring, works as a fin during boost and a canard after burn string breaks and ring slide forward to canard position. I still struggle with the physics of it, how does a ring shaped glider figure out which way is “up”, but it sure looks cool.

That is really cool! Looks like it would be a ton of fun fly!

 

[jqavins]

As we all know, one of the challenges in designing a rocket glider is having a mechanism the shifts the CG and/or CP to transition from a stable rocket (CG ahead of CP) to the glide configuration (CG and CP nearly coincident). Here's my novel solution. Mind you, I don't know the second thing about designing a glider, so I'm sure this needs a whole lot of work.

Think of it as a boosted dart. The booster and the "dart" are each designed to glide, with static margins near zero, but the dart acts as a nose weight making the launch stack stable.

 

[Mugs914]

Cool idea!

The Centuri Space Shuttle from years ago sorta used the same technique. The orbiter part acted as nose weight for the booster during boost. (Oddly enough, the motor was in the orbiter as well so the "booster" was lifted by the orbiter....) Both glided back after separation.

 

[neil_w]

I like it! My main concern (other than that the "dart" needs more wing area) is that for the dart to meaningfully move CP of the full stack forward, it'll need to be very heavy for its size, and therefore unlikely to be a reasonable functioning glider. It's possible there's a way to finesse the problem so it'll work. I too know very little about gliders; what I know at all is from reading Frank Burke postings here.

 

[jqavins]

I did need 35 grams in the dart, so I figure it will a very steep glide path and this a short glide. As long as it doesn't come in ballistic or tumble, I'll call it a glide and be happy.

 

[BABAR]

Not quite the same but a bit similar

Fake Wulf
https://archive.rocketreviews.com/reviews/all/rokit_fake_wulf.shtml
I like the idea. If i get it right, the dart doesn’t glide, it must have a streamer or chute, basically it is your ballast nose weight. Would be nice if you could dump the motor (reduce mass of the glider), trying to figure out how to do motor eject AND separate the dart with a chute or streamer. Without electronics, it is challenging to get a single ejection charge to reliably do two separate things. I’d like to see this bear some fruit!

 

[jqavins]

No, the dart does glide. It's heavy, so it doesn't glide far, but it is trimmed to glide such as it can. So a rocket stack goes up, and two gliders come down.

 

[lakeroadster]

After this, everyone (except Neil ) is invited to play.

How about a scratch build "Beneath The Planet Of The Apes Rocket"....

BT-60 based, flying on a D12. Everything ahead of the BT-60 is a custom turned pine nose cone.. and a couple ounces of ballast to give it a decent stability margin.

Used an internal lunch lug so as to not mess up the bullet shape.

 

[jqavins]

Do you really need the nose weight? Pine is so dense (by model rocketry standards) I would expect that nose cone to plenty heavy enough.

Oh and, yeah, I like it.

 

[lakeroadster]

Do you really need the nose weight? Pine is so dense (by model rocketry standards) I would expect that nose cone to plenty heavy enough.

Oh and, yeah, I like it.

Stability is 0.47 w/o the 2 ounces. With the ballast it's 1.14.

I'm ok with lower apogee flight's.. I think it makes the flight more exciting.

 

[jqavins]

Sure, whatever it is is OK. I'm just really surprised you need the weight. But if you do, you do.

 

[lakeroadster]

Sure, whatever it is is OK. I'm just really surprised you need the weight. But if you do, you do.

Seems to be par for the course for the rockets I build. Eye Candy -vs- Aerodynamics

 

[BABAR]

How about a scratch build "Beneath The Planet Of The Apes Rocket"....

BT-60 based, flying on a D12. Everything ahead of the BT-60 is a custom turned pine nose cone.. and a couple ounces of ballast to give it a decent stability margin.

Used an internal lunch lug so as to not mess up the bullet shape.

https://www.walmart.com/ip/Estes-Hunter-s-Choice-Model-Rocket-Launch-Set/38578739or just buy the Estes Magnum load cut the body tube be shorter and paint it gold!

 

[BABAR]

How about a scratch build "Beneath The Planet Of The Apes Rocket"....

or just buy the Estes Magnum load cut the body tube be shorter and paint it gold!

https://www.walmart.com/ip/Estes-Hunter-s-Choice-Model-Rocket-Launch-Set/38578739

 

[boatgeek]

Seems to be par for the course for the rockets I build. Eye Candy -vs- Aerodynamics

That one does have dinky little fins, but scale has its demands! It wouldn't look right with bigger fins.