Terrier-Orion Two Stage Conversion

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jqavins

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Thread necromancy to go along with project necromancy.

I was looking yesterday for something I could build quickly, in time for a launch next weekend. Going through my build pile, salvaged parts, and partial builds I discovered that I'm really a lot closer to the rebuild on this than I remembered.

I had the booster tube with the rear ejecting motor mount, three of the four booster fins, and the more or less complete sustainer. I cut a new fin for the booster..
PSX_20201004_153403.jpg

Today I cleaned up the roots of the other three fins and got them in glue on the jig. While prepping the roots of the three salvaged fins, I broke a chip out of one corner. I went ahead and glued the fin to the tube, and I'll glue the chip into place after the edge glue dries and before I apply new fillets.
PSX_20201004_143940.jpgPSX_20201004_144046.jpg
 

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mbeels

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Cool, this looks like a fun one. Will it be BP to BP gap staged?
 

jqavins

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Yep, that's the plan. Instead of venting the booster tube near the top, gas flow is ensured by using that pressure to expel the motor mount. That is, the expanding volume serves instead of a vent. Or at least that's the idea.

I've run into a snag. When I designed this, I simmed the static margin for the stack, the margin for the sustainer, the altitude, but I didn't know enough to check the rod exit speed. Even on a C6-0 and a light A8 it's really dicey. What I wouldn't give for those old B14-0s to come back.

I may need to go to a 24 mm booster and use C11s or D12s. But that would mean starting from scratch, and there's no way it'd be done in a week.

I'll just beg a little and see if the RSO will allow it. Definitely a heads up flight.
 
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kuririn

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How about using a longer rod?
 

jqavins

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I simmed that too. Up to six feet and it's still sketchy. And if I want to launch it at the club launch then the rods are the rods.
 

UhClem

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I am very curious about the booster. I was thinking about trying to make a Boosted Zombie but couldn't think of a good way to get a recovery device out on the booster with BP gap staging.
 

jqavins

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Rear ejection. Normally with gap staging one must place a vent hole just beneath the next stage motor to ensure that hot gas and particles flow up the stuffer tube rather than pressurizing it and the space around it. In this case, instead of a vent, I'm letting the motor mount slide backward so the expanding volume behind the sustainer motor serves that purpose. When the motor mount kicks out, a streamer is deployed from between its centering rings.

The scheme involves several parts that will be much easier to explain later when I have a real keyboard; I hate thumb talking.

---------

OK, I'm back. Here's an illustration. Not To Scale
1601901367743.png

Ignition gas and particles come up the motor mount extension and coupler stock. Gas is vented through the perforated centering rings that hold the coupler stock and begins pushing out the motor mount. The motor mount tube and coupler stock have a lot of overlap initially, so they remain in contact for a while as the motor mount moves aft. The sustainer motor lights, the booster motor mount is ejected, and the booster streamer is deployed.

ALSO, Progress:

Last night before bed I glued in that chip.
 
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MALBAR 70

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Will the 0 delay motor build up enough head pressure to eject the motor mount, light the sustainer and aid in separation?
 

mbeels

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Will the 0 delay motor build up enough head pressure to eject the motor mount, light the sustainer and aid in separation?
Joe has a video here somewhere of a ground test that does just that. Joe, is your drawing in post #38 the same setup you tested in the ground test video? It looked like it was effective.
 

jqavins

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The following was written and not posted a couple of hours ago.

Well, I think so. And if it doesn't manage separation, then the sustainer's exhaust certainly will. If it kicks the motor mount only far enough to free the streamer, that'll do. And if nothing works right then it'll self-destruct.

We shall see. If they let me launch. And the more I think about it, the more I think they shouldn't. It's not just low rod exit speed; it's that followed by staging, which is a recipe for a landshark.

I'll say it one more time: I want B14-0s.


Now back to the present.

Yes, it's the same setup now as then. The destruction was caused by an attempt to augment the ignition charge with a small fraction of a gram of loose black powder. We found out later that the dispenser malfunctioned and dispensed a whole gram or so. So it's never actually been tested with a stock engine or slightly enhanced one.
 

Charles_McG

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BTW, I have successfully staged 29mm BP motors with the loose powder sitting on top of the booster grain. It can work.
 

jqavins

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Sometimes I have to let a problem sit, and think about it for a few minutes occasionally, before the eureka moment arrives.

I was worried about rebuilding the booster with a 24 mm MMT because the difference in diameter between the MMT and the airframe tubes' diameters is small and doesn't leave much room for the perforation of the static centering rings. And it also doesn't leave much room for the streamer.

Today I realized, what should have been obvious, that I don't have to rebuild the booster from scratch. I can rebuild only the ejectable pod, with a piece of BT50 for the motor and adapt down to BT20 for most of the length. That way the rest of the booster, including the static coupler stock and perforated centering rings, can stay just as they are.

I won't be able to work on it for a couple of weeks, as I'm away from home. Stay tuned.
 

Sooner Boomer

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I've got a similar project I started, but let it sit and "mellow". I decided to go 24mm gap staged to 18mm. The booster stage really, really wants to be stable, so I added a bunch of weight in the tail. This means I have to add a bunch more into the nose of the upper stage to keep the assembled rocket stable. Without the tail weight, the booster would want to keep flying, and core sample. I didn't want to add the complexity of active recovery, trusting to unstable, tumble recovery. It may turn out to be a single-use rocket.
 

jqavins

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Look out for the trap I fell into: rod exit speed. I had to go up from 18 mm to 24 mm in the booster even without a bunch of added weight. With the weight you're adding at both ends, a D12 might still not be enough.
 
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Sooner Boomer

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This was my last sim in Open Rocket, as of 11/18/13

..... well, how do I post an OR file now?
 

jqavins

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Below the box I'm typing in, to the left, ther's the "Attach files" button. Should be self-explanitory from there.
 
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smaire

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Not certain where you stand on this, but take a look at Evan "Buzz" Nau's September/October 1997 issue of "Sport Rocketry", "Investigations into Gap-Staged Booster Recovery". The article is available on "Ye Olde Rocket Forum" site.

I have done a boilerplate Nike-Nike Smoke with an 8-1/8 booster. Sustainer did ignite, but booster was affixed to tightly to sustainer and was immolated by the sustainer. Revisions in work.
 

jqavins

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I have a plan, but am held up by a lack of centering rings, the lack of hand-eye coordination to make rings by hand that actually center anything, and lack of access to a machine to make them. I need rings for BT-50 to an oddball Quest tube.

And lately I've been discouraged by some bad launch experiences and I'm hardly doing anything rocketrywise except reading and shooting my mouth off on the forum.
 

jqavins

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I haven't got the dimensions at hand (I'm away from home) but what I need is to put a piece of BT-50 into the lower section of the Quest Terrier-Orion, which is not an Estes-size tube. It's close to BT-55 or -56, but not quite.

So, either two such centering rings, or a pack of B14-0s.
 

tsmith1315

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Perusing payloadbay.com, it looks like what you need could be 1.338"OD with a 0.976" hole...
 

jqavins

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Sounds about right. I'd gladly 3D print or laser cut them if I had access. There is a maker space inside one of the localish public libraries, but they were only open on weekdays, and after 5:00 only on Thursdays, and that was before COVID. The last time I checked they weren't open at all.
 

tsmith1315

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Next time I'm doing that sort of thing, I'll make a couple and see how they turn out.

I have double-sided PCB in 0.033" and 0.050", 0.125" craft plywood and 0.125" G10. Would any of those work for you?
 

Sooner Boomer

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OK, you might have just motivated me to complete my build. I've got some stuff already glued together, but I stopped working on the project because I needed to weigh the tail weight and didn't have scales that would work. I'll take pictures to show how I've solved some of the problems you've run into.
 

jqavins

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I have double-sided PCB in 0.033" and 0.050", 0.125" craft plywood and 0.125" G10. Would any of those work for you?
Yes, any of those would do. Thank you!

I'll take pictures to show how I've solved some of the problems you've run into.
The biggest problem I've run into was realizing, after I had everything glued up, that a C6-0 wasn't going to get me sufficient rod exit speed. Since B14s are no more and a C5-0 has never been, I have to upsize the booster motor mount to take a D12.
 

Sooner Boomer

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Here's what I did

First I started playing with Open Rocket to see how the parts work together. Then I started playing with the individual stages. From the beginning, I had intended on making this a two stage rocket. The bottom stage will be stable after seperation. Not a good thing, as it will core sample. The solution is to add weight in the tail until it becomes unstable as a single stage. OR thinks about 1.5 oz will do. I've got some solid core solder I will epoxy in, down the length of the tube. This is going to make it heavy. Obviously, it will need a 24mm motor.

The original kit (work in progress)
kit.jpg


Another problem is that there needs to be venting for the gap staging to work. One could perforate the centering rings to do that. I decided to put strips of balsa down the motor mount to center it.

mm.jpg

top.jpg


This is how it fits in the body tube

top2.jpg
mm2.jpg


and how the plastic shroud between the stages looks

shroud.jpg


So... What I need to do is to cut the tail weights and glue them on, punch a couple of holes at the top of the motor mount tube for venting, glue fins on both stages, fabricate and install motor mount in upper stage.

I think I'll recover on a plastic streamer. I think this rocket can get some good altitude to it.
 

jqavins

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The use of strips instead of centering rings is a nice idea. Where I have the one perforated centering ring that allows the gas to push the booster motor mount out, strips like that would have been a better idea. If I build this (or something like it) over from scratch I'll do it that way.
 
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