Neil_W's half-baked design thread

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BABAR

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Here's a 2-stage version:
View attachment 468469
The required enlargement of the sustainer fins makes it look a little more traditional (albeit nice). And here's what the sustainer looks like on its own:
View attachment 468470
I don't think I would trust those fins to survive boost *or* landing.
First, as always, cool.

second, sustainer fin problem easily solved with rear eject. For flight purposes, stick a section of Nerf Dart or tape on the nose tip to reduce chance of breakage since this will be point of “First Contact” on landing (not the Star Trek kind, either!)

third, is BOOSTER stable post staging? If so, you are indeed looking at a true Core Sampler. If NOT, does the surface area of the fins provide enough drag for a safe tumble recovery? Options include deploying a small Nomex streamer tucked around the sustainer motor mount, or mounting accessory cluster pod or pods on the booster. Simplest would be a 1/2A3-2T BT-5 pod, just long enough for motor, wadding, streamer, and nose cone. The delay allows the sustainer to stage and separate before the auxilliary pod pops the streamer.

you would be fine IMO with a single pod, the asymmetric thrust assuming you put the pod right up against the main body tube is negligible. If you are a purist, or for aesthetic looks, use two, one on each side. Gives you more redundancy.

another advantage of the smaller pod motors, if the main doesn’t light, the auxiliaries are likely too weak do get the rocket off the pad. Mildly embarrassing but not a safety risk. If the main lights and the auxilliary does not, at worst you are looking at the same core sample you would have otherwise had. Not optimal, but a cone less rocket tube coming down open tube end first is unlikely to do much damage, except possibly to your relationship with the RSO…. Actually, if the auxilliary does NOT light, it increases the probability the booster will be UNSTABLE (good thing) as it will be a bit more tail heavy, so better chance of tumble.
 

BABAR

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If you go Auxilliary root, do NOT use a zero delay motor on the AUXILLIARY, obviously you need it for the main assuming BP gap staging. If you do you will deploy the streamer AT or near Staging. This sounds good, but it’s not. The booster will be at or near MaxV, this is the WORST time to deploy a streamer. I know, I tried something like this with a parachute. Came down with one shroud line intact….

you can argue that if you nest the streamer in the sustainer it is EXACTLY when you will deploy it, but in that case you HAVE no other option (except maybe to fold it up kind of tight, so it unravels slowly. Problem with this is it may not unravel at all….)
 
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BABAR

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A cool part of your design if you go two stage is it naturally vents into the small gap around the “plasma core.” You can not get a gap position better than than, gases will go straight forward up and around the sustainer motor. Perfect.
 

jqavins

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third, is BOOSTER stable post staging? If so, you are indeed looking at a true Core Sampler. If NOT, does the surface area of the fins provide enough drag for a safe tumble recovery? Options include deploying a small Nomex streamer tucked around the sustainer motor mount, or mounting accessory cluster pod or pods on the booster. Simplest would be a 1/2A3-2T BT-5 pod, just long enough for motor, wadding, streamer, and nose cone. The delay allows the sustainer to stage and separate before the auxilliary pod pops the streamer.
Another option is to rear eject a streamer from the booster.

Gap staging typically involves vent holes up near the sustainer motor. One can, instead, use an expanding volume to keep ejection gas moving upward; this is done by using a combination of vented and solid centering rings and coupler stock to light the sustainer motor and eject the booster motor pod and let a streamer out.

See my Quest Terrier-Orion two stage conversion build thread for details. There is a ground test which, despite it explosive climax, does provide evidence (if not proof) of concept. It's a slightly complex build, but a lot less so than many of Neil's previous builds. And it provides, in my opinion, a nice elegant solution.
 

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Another option is to rear eject a streamer from the booster.

Gap staging typically involves vent holes up near the sustainer motor. One can, instead, use an expanding volume to keep ejection gas moving upward; this is done by using a combination of vented and solid centering rings and coupler stock to light the sustainer motor and eject the booster motor pod and let a streamer out.

See my Quest Terrier-Orion two stage conversion build thread for details. There is a ground test which, despite it explosive climax, does provide evidence (if not proof) of concept. It's a slightly complex build, but a lot less so than many of Neil's previous builds. And it provides, in my opinion, a nice elegant solution.
I get nervous trying to reliably get one expanding gas cloud to do TWO things, light the sustainer AND blow the laundry.

with Neil's design, easy to run a motor mount chimney forward, stop about 3 to 5 mm below nested base of sustainer. Gases flow up chimney. Circumferentially bath the sustainer motor and continue up and around sustainer base out the gap around the narrow segment. Bob's your uncle.
 

neil_w

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I don't think about any of that stuff at this very early stage of design. To be sure, gap staging implementation considerations could render a design impractical, or force significant changes, or push the design back to a single-stage.

But that's all for later, if at all.
 

jqavins

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It's been a little while with no posts. You know we all wait eagerly for new half baked ideas.
 

neil_w

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I’m trying to revitalize this thread a bit, but right now I’m at the beach. 😀
 

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Aren't those beaches where the original Jaws was filmed? Da-da, da-da...

-Bob
 

jqavins

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From HGTV.com (the headline result from Googling (jaws filming location)
Though the film takes place in the fictional town of Amity Island in New York, it was actually filmed throughout Martha's Vineyard, Mass. (Long Island was considered "too busy" — the filmmakers wanted an island that would feel eerily empty to filmgoers.)
Why HGTV, I couldn't say; they were probably doing an episode of something out on Martha's Vineyard; "Jaws was filmed here."
 
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