Someone build this for (any reason other than) the summer contest

Creative and looks cool nice job

I might give it a try, but I decline to be pinned down about it.

neil_w said:

I'm not sure I get the point of trying to inject humor into this thread. This sort of thing really gets under my skin.






(hope I don't need to add the implied :wink:, but there I did it anyway)

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I think you designed this rocket JUST so you could make those PUNs...

snrkl said:

I think you designed this rocket JUST so you could make those PUNs...

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Stop needling me.

To be serious for a moment: I think about building this periodically. What usually stops me is that I get bogged down trying to figure out how to take it three steps further, with a clear upper body tube and a two-piece separation like a real syringe. That turns out to be really hard, and so then this design goes back into hibernation for a while. I hope to build it in some form some day.

OK, how about this:

1. Separately make a top section an a bottom section out of clear material.
2. Join them with a coupler that is black and looks like the plunger's rubber piston.
3. The motor mount is built into the plunger shaft.
   • The shaft might be the motor mount itself, or a larger tube that contains the motor mount.
   • Either way, this requires centering rings.
   • The forward ring is easy; it's build into and hidden by the coupler.
   • The aft ring presents a challenge to integrate visually. Maybe use a sheet of clear material and make it flush with the aft end of the outer, clear tube. That would be open in a real syringe, but some compromise is probably unavoidable.
4. The laundry is made to look like the liquid medicine forward of the coupler
   • EDIT: Better yet, line the inside of the upper clear tube with colored cellophane to simulate the liquid. The laundry is behind that; if it's the same color as the cellophane then should be unobtrusive.

Okay, given this is outside the norm anyway.

What if you DON'T use rings? What if you just used flat plates for the plunger and the barrel flange? Will that give you base drag for stability? You're not going to get any altitude records anyway.

Clear tubing may be easy to simulate, maybe even use a soda bottle. This gives you clear outside surface. Inside that you put your structural tube, painted to simulate air and fluid contents.

Design lends itself to rear ejection.

Kind of similar to Gary Byrum's Magic Dart

https://www.rocketryforum.com/threads/summer-build-off-contest-magic-dart.134448/page-5

Depending on how big you wanted to make this, one of those tube light protectors you can get at Lowe's dirt cheap would be a pretty good airframe. Pretty darn close to being a BT 60 size.

I am amused at the attention this design is getting all of a sudden. I need to do a bit more simulation, now that I'm better at it and have a reasonable trick to simulate the rings. A build of this, if at all, is still in the future. I have a substantial to-do pile to work through before then.

jqavins said:

Separately make a top section an a bottom section out of clear material.

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If I went clear, I'd probably not want to have a split in it. Should be one solid piece.

EDIT: Better yet, line the inside of the upper clear tube with colored cellophane to simulate the liquid. The laundry is behind that; if it's the same color as the cellophane then should be unobtrusive.

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Now that is a pretty good idea. Will keep it in mind.

Clear adds a lot of extra hassle, but could help put the whole thing over the top.

BABAR said:

What if you DON'T use rings? What if you just used flat plates for the plunger and the barrel flange? Will that give you base drag for stability? You're not going to get any altitude records anyway.

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Although I certainly tend to build draggy rockets, I'd rather not completely capitulate and just use the plates here. I'd like this thing to fly a *little*.

Clear tubing may be easy to simulate, maybe even use a soda bottle. This gives you clear outside surface. Inside that you put your structural tube, painted to simulate air and fluid contents.

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Another good idea! That basically means a clear "wrap" tube around a normal rocket... although that wouldn't work well for the rear portion of the main tube that has only the plunger inside... you're really want to see the actual plunger in there.

If the next OR version comes through with transparent tubes, I should be able to make a spiffy model of it.

Gary Byrum said:

Depending on how big you wanted to make this, one of those tube light protectors you can get at Lowe's dirt cheap would be a pretty good airframe. Pretty darn close to being a BT 60 size.

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I had not seen those before. The T12 protectors are indeed pretty close to BT60. But not exact, which means I'd either have to custom-make centering rings and the first transition, or else do some creative shimming/wrapping.

Given that Apogee sells BT60 clear payload tube for five bucks and change for 18", I'd probably just go that route, since there'd be enough other headache to deal with here.

neil_w said:

I had not seen those before.
Given that Apogee sells BT60 clear payload tube for five bucks and change for 18", I'd probably just go that route, since there'd be enough other headache to deal with here.

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Those weren't available back when I built my upscale Constellation. The light shields are so close in size to a BT 60 that neither tube will fit inside the other. The light shield is about 1/32" wider, or rather, 1/64" wider all the way around.

The clear payload tubes became available about a year later, best I can recall. It would be the better option of course.

Oh Goody! We get another shot at it...

Gary Byrum said:

The clear payload tubes became available about a year later, best I can recall. It would be the better option of course.

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Something that's been bothering me w/respect to the clear tube approach is that once you have a clear tube for the barrel, you really want the first transition to be clear as well. Apogee actually makes clear transitions, but they're a bit bigger and would require this whole thing to be upscaled a bit. Not that that wouldn't be awesome, but it'd probably be bigger than I'd want to build.

So we're back to the original thread title. Someone please build this. BT80 clear barrel should work out nicely with a 24mm core in the plunger.

Break the rules Neil. Make the transition using a chrome wrap on it or something. For that matter, they used to be made of just metal without a transparent shaft.

Let's try that pic again.

That just scares me.

Imagine what it was like for the kids. It's no wonder they were sheared skitless to get a shot.

Looking at that image of yours Gary makes me wonder which was worse, the shot, or the reason you'd need a shot?

neil_w said:

jqavins said:

OK, how about this:

1. Separately make a top section an a bottom section out of clear material.
2. Join them with a coupler that is black and looks like the plunger's rubber piston.

Click to expand...

If I went clear, I'd probably not want to have a split in it. Should be one solid piece.

Click to expand...

Maybe this was clear, maybe it wasn't, so I'll try to clarify just in case. The idea was to make the black piston, i.e. the rubber part on a real syringe, the coupler. That way you can make the seam between clear tubes disappear, hide an upper centering ring for the motor mount inside the black coupler, and have room in the upper portion for the parachute, wadding, etc.

jqavins said:

Maybe this was clear, maybe it wasn't, so I'll try to clarify just in case. The idea was to make the black piston, i.e. the rubber part on a real syringe, the coupler. That way you can make the seam between clear tubes disappear, hide an upper centering ring for the motor mount inside the black coupler, and have room in the upper portion for the parachute, wadding, etc.

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It was, ahem, "clear". I don't think the piston would hide the seam in the clear barrel. Could be wrong though, hard to know for sure without trying it.

Gary Byrum said:

Let's try that pic again.

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Gary, the picture still isn’t right. It’s upside down.

BABAR said:

Gary, the picture still isn’t right. It’s upside down.

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So, my syringe will not go into space today?

Gary Byrum said:

So, my syringe will not go into space today?

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Yes, it doesn't look like you'll be able to inject it into orbit.

The original model I posted did not have any functionality to the two rings. I tried putting in a guesstimation of their effects, using fins. It improves the outlook considerably:


I was able to reduce the nose weight to 0.4 oz (could do .5 to get just a wee bit more margin). Or even a bit more to make way for the QuestJet D motors.

The CG is really quite far forward in this, because the plunger extension out back will weigh very little. The rings, if I'm simulating them correctly, give a pretty good amount of surface area to pull the CP backwards. Seems doable.

It would probably be a more fun model upscaled a little from this.

Interesting how it looks like a sounding rocket....uh....er sounding syringe?

Just to add to the challenge, does anybody else see that this is pretty much a ringfin kitbash on a Saturn V??

Gary Byrum said:

So, my syringe will not go into space today?

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Actually, if NASA has a southern Hemisphere launch pad, you should be good.

Neil, what if you take some artistic/engineering license and bump up the front to back length of the rings?

BABAR said:

Neil, what if you take some artistic/engineering license and bump up the front to back length of the rings?

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According to my current sim there's no reason to do this; there's good stability margin without excessive nose weight. Of course this assumes the way I'm simming it is reasonably accurate; I'm using a ring-equivalent fin arrangement that.... I think it was Nytrunner who first suggested it. It made good intuitive sense to me, so that's what I'm using.

If my sim is overstating the effect of the rings, then indeed larger rings might be useful. For the moment, though, I can't see any reason to go there, unless you know something I don't...

neil_w said:

According to my current sim there's no reason to do this; there's good stability margin without excessive nose weight. Of course this assumes the way I'm simming it is reasonably accurate; I'm using a ring-equivalent fin arrangement that.... I think it was Nytrunner who first suggested it. It made good intuitive sense to me, so that's what I'm using.

If my sim is overstating the effect of the rings, then indeed larger rings might be useful. For the moment, though, I can't see any reason to go there, unless you know something I don't...

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No, don't KNOW anything you don't. I haven't even computer-simmed it. I have mind-simmed it, and my spider-sense is tingling.......

It may also be that the rings actual provide much more fin surface area than appreciated just looking at 2D drawings, which is what my mind-simming is doing. I also am not seeing on the 2D drawings the connecting fins between the rocket body and the Rings, so I can't appreciate how many and how big they are.

Also, the note on the file saying, "Warning. Discontinuity in rocket diameter. Too many parallel fins" I keep hearing it with that Lost In Space Robot from the old TV series voice, "Danger Will Robinson."

I shall offer a quick digression on the ring-equivalent sim method I am using.

1. calculate the circumference of the ring
2. create a fin set with the following characteristics:
   1. rectangular shape
   2. root edge same as ring width
   3. position same as ring
   4. Total area of fin set equal to area of ring

Originally, this was done while also making the height of the fins equal to the distance from the inner BT to the ring, so that it looks the same in side view. In this case, for the front ring, that would have required more than 8 fins in the set (disallowed by OR) so I made the fins taller and used... I think 7 of them, or thereabouts. A 3" ring generates quite a bit of "fin area" when wrapped around a BT60.

If anyone wants to weigh in on whether this has any likely connection to reality, I'm all ears. To me it passes the basic sanity test because the fin set is roughly equivalent to chopping up the ring into small pieces and attaching them to the body. In cases where the diameter of the ring is closer to the diameter of the inner BT (how close exactly? dunno), and the airflow might not be as free, this whole thing almost certainly doesn't work. Given how short the rings are, and the substantial distance between them and the inner BT, I thought it would work in this case.

neil_w said:

After some instigation in another thread, I concocted a new design that amuses me but I do not plan to build.

I present to you the Space Needle:

Needs some tweaking but could be made to fly.

View attachment 290073

View attachment 290074

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You know....I’m thinking if we put a spring in the compression section of the syringe and figure out a way to drop little black powder pellets cyclically, we could turn this into a “Project Orion”-like spinoff.

Ohhhh, perfect rocket for those of us with multiple chronic illnesses!