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The issue is with finding elliptical tubes of specific, particular sizes. For instance, the tube for my current project is 33 x 66 mm; since the original point was to reduce area and circumference of the tube relative to a circular tube that holds the same cluster, it has to be that particular size, or quite close to it, or you start rapidly losing that advantage. This is for a cluster of two 24 mm motors. One could obviously do the same for other motor sizes, and one would still need a rather particular tube size for each motor size. And one might want mandrels for the corresponding couplers, though those could be 3D printed. Ellipse-to-ellipse and ellipse-to-circle transitions could also be 3D printed.

So the issue isn't just where to get elliptical tubes, but where to get the right elliptical tube.
 
I can see that being an issue, if you have that specific requirement in mind. I was looking at the other way around, where I'd find a suitable tube as a mandrel, then design a rocket around what I could do with that.
 
I'm bringing this thread back to the top again. This is a rocket I call Antares; its a gap-staged model, but got a bit unique when I decided that I wanted the booster and sustainer to both have boat tails. The sustainer is a bit Astron Sprint-like, its the same diameter and uses the same cone as the Sprint XL. And, as mentioned, has a boat tail. The booster is larger diameter than the sustainer, so it has a transition up from the coupler to the body diameter, then terminates in a boat tail.

29405148596_6b817aa987_b.jpg

29359723411_c582c424c6_b.jpg



The tricky part comes from having to accomodate a paper transition boat tail while still providing a connection for the booster to the sustainer. So, I made the booster 29mm and the motor mount in the sustainer 24mm. The sustainer's motor mount is centered in a 29mm tube, which is in turn centered in and sticks out of the main body tube. This lets the paper transition cone mount on the 29mm tube's outside, while also providing the inside diameter for a coupler sticking out of the booster's 29mm mount tube to plug into. The sustainer's 24mm mount is partially (but not too far) cantilevered back into the 29mm coupler from the booster. I hope all that makes sense...

On a 24 & 29 mm black motor combination, the lift off would be quite slow if using the E16-0 or F15-0 as booster motor. According to Rocksim, it would use every bit of a 6' rail. But I think it would make a pretty cool flight, at least on a calmish day. Fastest lift off combination appears to be an E16-0 to C11-7, which only needs 4.5' instead of 6'; that might be the best first-flight pairing, and should still hit about 1400'.
 
I've been thinking, now and then, about how to put a boat tail on the sustainer atop a booster, and never thought of this simple solution of using an hourglass. I've been trying to find a way to burry the boattail in the forward end of the sustainer, but this is so much more straightforward. Hats off.
 
Since this is now final and official (i.e. I'm gonna build it), might as well revive this thread:
attachment.php


Should be a fun build.

avalon_final_or.png
 
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I'm bringing this thread back to the top again. This is a rocket I call Antares; its a gap-staged model, but got a bit unique when I decided that I wanted the booster and sustainer to both have boat tails. The sustainer is a bit Astron Sprint-like, its the same diameter and uses the same cone as the Sprint XL. And, as mentioned, has a boat tail. The booster is larger diameter than the sustainer, so it has a transition up from the coupler to the body diameter, then terminates in a boat tail.

29405148596_6b817aa987_b.jpg

29359723411_c582c424c6_b.jpg



The tricky part comes from having to accomodate a paper transition boat tail while still providing a connection for the booster to the sustainer. So, I made the booster 29mm and the motor mount in the sustainer 24mm. The sustainer's motor mount is centered in a 29mm tube, which is in turn centered in and sticks out of the main body tube. This lets the paper transition cone mount on the 29mm tube's outside, while also providing the inside diameter for a coupler sticking out of the booster's 29mm mount tube to plug into. The sustainer's 24mm mount is partially (but not too far) cantilevered back into the 29mm coupler from the booster. I hope all that makes sense...

On a 24 & 29 mm black motor combination, the lift off would be quite slow if using the E16-0 or F15-0 as booster motor. According to Rocksim, it would use every bit of a 6' rail. But I think it would make a pretty cool flight, at least on a calmish day. Fastest lift off combination appears to be an E16-0 to C11-7, which only needs 4.5' instead of 6'; that might be the best first-flight pairing, and should still hit about 1400'.

I'm very intrigued by this one. I'd really like to attempt to build it... And I wouldn't need an L1 cert. to fly it!
 
Is the blockyness in the fins deliberate? I looks llike some really low res rendering, but the rest isn't like that.

Nope, that's just the best I can do in OR; each of those fins is divided into 9 segments. Maybe if I get bored I'll subdivide it into a larger number so it'll look a bit smoother (tedious) but for now you just have to sort of imagine it. Here's the pre-build thread. If I can get it built according to the model, I think it'll be neat. The decor still needs work, but the rest of the design is final.

edit: OK, I made the change and updated the image in my previous post. Looks better (still blocky, but less so).
 
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I posted about this in Oddrocks; I'm working on an induction tube model that uses Gas dynamics for stability. Just for the heck of it, I attempted to make it in OpenRocket, and I'd like to try it in Rocksim once I make that purchase.

Phantom body tube makes OR unhappy, but I got the weights pretty close to the physical model.GBIsim.jpg
 
Anyone have anything new and interesting? I haven't done any new design in a while, as my current builds are keeping me amply busy, but I want to get hacking with the new version of OR (supporting pods) whenever it comes out.

I still really like EXPjawa's Sagittarius Arrow, wouldn't rule out using that as a starting point for a new build at some point. Would be fun to build something with those signature strakes. :)
 
Not from me at this time. I've been busy the last few months in simming and refining models for both MAC Performance rocket kits that I've recently built, plus a few spin offs. A lot of work in those, but the models are as accurate (in terms of mass and placement) as I've managed so far. Now to correlate them to real data...
 
Not exactly new, but I have updated my RocSim9 file for the 4x Orbital Transport in order to get the decals on correct. The RocSim9 file has been multiplied by a factor of 4 to get the upscale, but I have not edited the simulation so far to have the correct materials for the upscale.

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  • 4x Orbital Transport.doc
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The Biohazard looks amazing! Is there a way to do all those tubes/rings in OpenRocket that I'm missing? I can't seem to find it...
 
The Biohazard looks amazing! Is there a way to do all those tubes/rings in OpenRocket that I'm missing? I can't seem to find it...

Ring tails are done using an "internal tube" and just making it larger than the BT. They are not factored in the simulation at all (other than for CG calculation).

The pods are implemented with tube fins, mounted to a phantom body tube (a zero length, zero wall thickness BT in the size appropriate to support the pods.)

To make the interior of the pods a different color, a separate set of *slightly* smaller tube fins was positioned concentrically to the outer tubes, and colored red.

The actual flight simulation of that model isn't worth much, given all the things in it that aren't simulated properly, but it looks nice. :)

If you want I'll post the OR file tomorrow, but there are numerous other files that have been posted by all different folks that use these techniques.
 
OK, I get it now.

Is there a way to do "fins on fins" - like Estes' Photon Disruptor, Alien Invader, or one of countless others?

Sorry for being such a noob!
 
Has OR been successful in adding functional pods to the program yet? That is one area that Rocksim does pretty well (pods, ring tails, tube fins, etc) and seems to make a reasonable difference in the sim results. It isn't perfect (or particularly user friendly), but it does a decent job. In Rocksim, simming a ring tail using an internal tube has no apparent impact on the physics modeling, but the ring tail tool does. I wonder if modeling it as an internal tube in OR is similar.
 
Is there a way to do "fins on fins" - like Estes' Photon Disruptor, Alien Invader, or one of countless others?

The new version (I don't know when it is likely to be released) will enable this, although it can be a bit of a chore to implement. Here's one I did to test it out:
attachment.php


Has OR been successful in adding functional pods to the program yet? That is one area that Rocksim does pretty well (pods, ring tails, tube fins, etc) and seems to make a reasonable difference in the sim results. It isn't perfect (or particularly user friendly), but it does a decent job. In Rocksim, simming a ring tail using an internal tube has no apparent impact on the physics modeling, but the ring tail tool does. I wonder if modeling it as an internal tube in OR is similar.

Well, "successul" is a value judgment. ;) The upcoming version does support pods, although the implementation has room for improvement. Perplexingly, ring tails are still not supported as a first-class component type. It is theoretically possible to create a ringtail using a pod, but I don't know how it would simulate (hmm, I think i need to try that out and see what it does).

sw_render.png
 
Interesting. I'd wonder if a pod-derived ring tail (or tube fin) would properly account for the drag of that part. I think that's why Rocksim broke them out into separate part types. Either way, I'm glad that OR is moving forward, unlike Rocksim which is stuck in 2010 or so it would seem. Unfortunately, it appears that Apogee is uninterested in further developing it (or removing long-running bugs)...
 
The new version (I don't know when it is likely to be released) will enable this, although it can be a bit of a chore to implement.

Is there an early access/beta that I can get to use this feature? I love weird fin configurations, but I don't love simming them...
 
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