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So I have gotten everything done besides motor mounts and paint. Current plan is for E12 booster and either a 24 or 29mm sustainer.
Open rocket sims the E12 to F15 combination as stable... barely. Plus there is the problem of a big enough place to fly it on both stages.
Made using a 3M 2” I.d. Mailing tube and a balsa nose cone made from the parts in the first post.
trying to come up with a name too.
Open rocket sims the E12 to F15 combination as stable... barely. Plus there is the problem of a big enough place to fly it on both stages.
Made using a 3M 2” I.d. Mailing tube and a balsa nose cone made from the parts in the first post.
trying to come up with a name too.
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d12 comes off the pad with the same thrust spike but lower mass, right? Would stage almost immediately....
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D12 shaves off 22 grams. That’s gonna buy you some stability. Plus since it is tumble recovery, the booster will be lighter and less likely to break a fin.
you Gonna put a tracker in the sustainer? If not, go with a D12-5 or maybe 7 for sustainer, at least for the first flight.
many reasons
less tail mass, so again helps stability.
IF this thing is still vertical at staging (obviously what you are hoping for!) it‘s already cooking velocitywise when it stages, so it’s gonna go a LONG way up, which means high potential for drift if you have any wind. May be a pain to find.
if for whatever reason this is NOT vertical at staging (and you’ve already suggested it’s borderline stable. “Danger Will Robinson,”) the less powerful motor inside the safer it is (not that I am EVER advocating launching any rocket let alone a multistage that you don’t expect to be stable, but meconium happens, so until you have a maiden flight that proves the design, I’d stay on the conservative side. If It’s gonna come into ground under power, better a D than and F.) And even if it just weathercocks (like multistagers tender to do) rather than comes in under power, it is gonna go a long way laterally, you are looking at a Loooooong walk even if it is only 45 degrees off vertical.
take a look at @rklapp post 549 sidewinder. Now imagine that with an F instead of an A.
https://www.rocketryforum.com/threads/updates.160959/page-19
Yeah, that right there was a scary flight. I think I would have needed new clothes for the ride home.
To be more clear, the two stage stability doesn’t seem to be an issue in any configuration; the stability issue happens when the first stage is gone. I am right at 1 caliber at that point (with an F15 loaded) and since there aren’t published weights for mailing tubes, I am making educated guesses.
It looks like I am going to go with 24mm in both to start. This is one to grow with anyway. There are some other things I would like to try with the general design at some point, so we will see what happens.
Right now it’s a wait for good weather.
To be more clear, the two stage stability doesn’t seem to be an issue in any configuration; the stability issue happens when the first stage is gone. I am right at 1 caliber at that point (with an F15 loaded) and since there aren’t published weights for mailing tubes, I am making educated guesses.
It looks like I am going to go with 24mm in both to start. This is one to grow with anyway. There are some other things I would like to try with the general design at some point, so we will see what happens.
Right now it’s a wait for good weather.
Should be able to easily run the sims in OR. We can do it if you give us the dimensions.
The problems with the Sidewinder is that the C11-0 was underpowered and the D12-0 was too heavy. I need to figure out how to add weight to the NC that can be easily removed afterwards.
The problems with the Sidewinder is that the C11-0 was underpowered and the D12-0 was too heavy. I need to figure out how to add weight to the NC that can be easily removed afterwards.
I have simmed in OR. Says it’s fine no matter how you shake it...BUT as a data reviewer I have learned to always question results when they are on the edge f acceptability.
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Would a hole with a plug that you could fill with sand work?
That could work for the balsa comes. Now what to do with the Nike Smoke cone?
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If it’s hollow, couldn’t you drill a hole in the bottom, make a paper funnel, fill it with sand,and put in a removable plug? Maybe a piece of foam earplug? I’m kind of brain storming/free associating here.
I like it.
(Gee, I just finished writing some potentially lame design suggestions for exchangeable nose weights in another thread.) I myself would go with some design that allows for a selectable washer stack. Since it is a balsa nose cone, you've got lots of options for that. STOP reading here.
Still reading? For a plastic nose cone there are surely ways to make an exchangeable washer stack system. Possibly this: Most glues wont adhere (or won't adhere well) to most plastic nose cones. But epoxy can be used to make a blob inside that can't pull through. This should work for a larger cone with a reasonably tough base: pour some really runny epoxy in through the hole in the base, then stick a short threaded rod through the hole, then turn the whole thing pointy end up so the epoxy runs down to the rod and cures around it. Add washers to taste, then lock the whole thing together with a nut. Next a coupling nut goes on, to connect an eye bolt.
I'm probably overthinking this. I do that.
Still reading? For a plastic nose cone there are surely ways to make an exchangeable washer stack system. Possibly this: Most glues wont adhere (or won't adhere well) to most plastic nose cones. But epoxy can be used to make a blob inside that can't pull through. This should work for a larger cone with a reasonably tough base: pour some really runny epoxy in through the hole in the base, then stick a short threaded rod through the hole, then turn the whole thing pointy end up so the epoxy runs down to the rod and cures around it. Add washers to taste, then lock the whole thing together with a nut. Next a coupling nut goes on, to connect an eye bolt.
I'm probably overthinking this. I do that.
For the Nike Smoke, would I need a release agent in the NC point or will Bobs epoxy not likely stick? It would need to be a long bolt. Just the weight of that would probably be enough.
Alternatively, I could decide I have enough 2 stage rockets and just rip out the 18mm and replace with 24mm with extra NC weight.
Decisions, decisions...
Already been thinking that.
I have already resigned the fact that, for multiple reasons, I am going with a E-D, D-D, or D-E configuration with the first flight(s). BUT.. if I choose to go with a E-F (F-F???) configuration, I have something very similar worked out to what you have drawn here. My idea is large screw-eyes holding in washers to add weight in the nose.
