More Half-Baked Designs Thread

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Thanks. I should get to the RS attempt(s) today or this weekend. I'll remember to try lengthening the boat tail as well as its rear diameter.

I'll keep y'all posted.
 
Has anyone done this? I bet someone has done this. Boattails move one's CP forward. Ringtails are quite effective at moving one's CP aft. When a boattail is placed inside a ringtail, which one wins?
View attachment 464060
The ring's pylons are visible in the bottom view. If it helps, the pylons could be extended forward to fill the boattail's profile up to the bottom of the body tube, but I bet that wouldn't help much if at all.

Looking at it, I see that it's similar to some air dropped bombs, and also to some torpedoes. But torpedoes can have guidance systems (the modern ones all do, if I'm not mistaken) and the bombs only have to be nominally stable.

Of course I could, and will, try it out in RS, and maybe OR too. (Wait, are ringtails that feature that OR lacks until the next release that's been just around the corner for a couple of years, or are ringtails available today?) I'm just not sure how far to trust the simulations for a model that's rather far, but not terrifically far into the weirdness zone.

If this works, it just begs to be tube launched. Before I spend the time to do the research, does anyone happen to know of a standard BT size (OD) and a common pipe size (ID) that are a good match for the purpose (close but not tight)? Don't trouble yourself looking, as looking is my job unless someone already knows.
@Dotini did something like this.

see post 47

https://www.rocketryforum.com/threads/another-finless-rocket.131953/page-2#post-2112750AnimistRingFin.jpg
 
Has anyone done this? I bet someone has done this.

If this works, it just begs to be tube launched.

you mean...

12-assembled-jpg.281509

https://www.rocketryforum.com/threads/another-finless-rocket.131953/
I'm amazed you don't remember posting to this thread! But please, put your own spin on it! I'd love to see what you can do!
 
Dotini also did this, Animist II, big brother to the Animist seen above.

DSC00235.jpgDSC00234.jpg

I can add that it is very sturdy and can take a rough landing. It goes very high, does not weathercock, and seems to be a natural backslider.

I suppose if someone wanted to tube launch it (but why?), they could add a canard ring or canard fins to center it in a tube.
 
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you mean...
12-assembled-jpg.281509
No, I mean what I sketched in post 141. The ring is the same size as the airframe (unlike Dotani's) and there is no stand-off pushing the ring back.

I did it up in RockSim over the weekend and then it slipped my mind to post it. RS says it's stable and has very surprisingly high drag. I'll try to remember to post tonight.
 
Dotini also did this, Animist II, big brother to the Animist seen above.

View attachment 464762View attachment 464761

I can add that it is very sturdy and can take a rough landing. It goes very high, does not weathercock, and seems to be a natural backslider.

I suppose if someone wanted to tube launch it (but why?), they could add a canard ring or canard fins to center it in a tube.
Again, nice look.

did this actually BackSlide with nose in place? I have seen many streamer and parachute rockets that have what I call a “Pseudo-BackSlide”. (Which may not the that “Pseudo”). Basically the deployed the nose and chute or streamer, nose came down hanging on the chute or streamer, the body of the rocket (still attached to nose and streamer) turned horizontal tail first with very slow tail first trajectory parallel to horizon will it fell, maybe better out, it descended attached to but parallel with the nose cone and chute, so it wasn’t “dangling” from the chute, in a horizontal orientation, and seemed to have a minimal added “backward” trajectory.

this seemed to happen more with my asymmetric fin rockets. I am pretty sure that asymmetric fin rockets need more fin area to be upward flight stable. They are not very efficient, I am sure I sacrifice some altitude, but good enough for government work or sport flying, and I think on my few flights with spectators they get a few more ooohs and aaahs (due to corkscrew smoke trail) than more classic and efficient 3FNC low and mid power rockets.
 
Again, nice look.

did this actually BackSlide with nose in place? I have seen many streamer and parachute rockets that have what I call a “Pseudo-BackSlide”. (Which may not the that “Pseudo”). Basically the deployed the nose and chute or streamer, nose came down hanging on the chute or streamer, the body of the rocket (still attached to nose and streamer) turned horizontal tail first with very slow tail first trajectory parallel to horizon will it fell, maybe better out, it descended attached to but parallel with the nose cone and chute, so it wasn’t “dangling” from the chute, in a horizontal orientation, and seemed to have a minimal added “backward” trajectory.

this seemed to happen more with my asymmetric fin rockets. I am pretty sure that asymmetric fin rockets need more fin area to be upward flight stable. They are not very efficient, I am sure I sacrifice some altitude, but good enough for government work or sport flying, and I think on my few flights with spectators they get a few more ooohs and aaahs (due to corkscrew smoke trail) than more classic and efficient 3FNC low and mid power rockets.
Yes, agreed on all points. Animist II backslid on a flight in which the streamer failed to deploy properly (I had left the rubber band on it). I've noticed this on other flights with proper deployment as well. IMHO, there is a lot to be said for models which land reliably without loss or damage, and do it over and over again. In only a short time, I will reveal my new pseudo backslider which will try to live up to that particular set of virtues.
 
I just ordered parts to make a quick and easy prototype. Bit Bertha nose cone and V2 boat tail with a BT-20 core hole. NYPower is a week away, and I just might have it ready to fly (built and swing tested) by then. It'll probably have to have launch lugs this time. (If I can't get a proper pipe size, I could use FARGs, but I don't expect I could get those ready by next weekend.)

Correction: Ordered the Apogee FARG for it.
 
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I just ordered parts to make a quick and easy prototype. Bit Bertha nose cone and V2 boat tail with a BT-20 core hole. NYPower is a week away, and I just might have it ready to fly (built and swing tested) by then. It'll probably have to have launch lugs this time. (If I can't get a proper pipe size, I could use FARGs, but I don't expect I could get those ready by next weekend.)

Correction: Ordered the Apogee FARG for it.
Who do you order those desirable Estes parts from?
I'm very interested in your experiment, and intend to keep making ringtails myself, and access to those parts short of buying the full kit might suit my plans very well.
 
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I ordered them from Balsa Machining Service. It would have been more precise to say Big Bertha nose cone and V2 boat tail equivalents, but in solid or cored-out balsa. When I do this full scale, 3 inch body and 29 mm motor mount, I don't know where I'll find the parts. But I'll cross that bridge when I come to it. It may just be the kick in the ass that I need to try some fiberglass fabrication, but if I can buy the parts rather than make them I will. (I'd rather build rockets than rocket parts, but that's me, and your millage may vary.)
 
I do indeed. Id' be happy if this thread becomes like that one, sims not required.

Well, this one's even less than half baked. And actually it's two. Y'know the design with a ringtail internally tangent to the body tube? Or a single tube fin attached on the opposite side from it's centerline, if you'd rather call it that. What about applying two of those rings, with interlocking slots where they pass each other? That'd look nifty, wouldn't it?
View attachment 394764

And what about one of these tangent ringtails but with the ring actually a Möbius strip? Oh, sure, the twisting of the ring would certainly play hob with its aerodynamics. That's OK, fix that by making the arrangement symmetrical by using two like the picture above. (Yeah, I did say "less than half baked".)
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Come on, somebody else!
Already been done. See attachment. One of the best flyers I've ever built.
 

Attachments

  • POF #516 - Sagittarius A Plan.pdf
    1.2 MB · Views: 43
Write now it's only primed, the weather has only gotten warm enough to paint in the last week. I haven't decided on the paint scheme yet; unless it's all one color it's going to be a masking nightmare.

I've flown it twice so far on an E30T and an F44W. The most amazing thing is most rockets fall somewhat short of the Rocksim altitude estimates. This bird has exceeded the estimates on both flights, by 14% and 40%, respectively. Flies straight as an arrow. It's one of my all time faves.
 
That's a beautiful design. I may need to add that to my virtual build pile. (Since the pile is virtual, it doesn't matter if no kit exists.)
Ooh, you built that one? I'd love to see some pics, and also hear how you did the paint sequence. It's a beautiful design, looks like the sort of thing I would design only a lot better.
Careful. Internally tangent rings are dangerously close to tube fins. And you shun tube fins. ;)
 
That's a beautiful design. I may need to add that to my virtual build pile. (Since the pile is virtual, it doesn't matter if no kit exists.)
Careful. Internally tangent rings are dangerously close to tube fins. And you shun tube fins. ;)
I have created a number of designs with interlocked rings like that. Regrettably none of them are as nice as that one.
 
I have parts for but haven't yet built a triple-interlocked internally tangent ring using 6" fins and a BT-80 body tube. It'll fly on larger 24mm motors. I want something relatively draggy so I can fly larger motors on a smaller field.
 
Ooh, you built that one? I'd love to see some pics, and also hear how you did the paint sequence. It's a beautiful design, looks like the sort of thing I would design only a lot better.
Here is a pic painted, no decals yet. The flight this weekend had a chute malfunction and a hard landing. One of the long stringers on the one fin cracked (reparable). If I were making it again, I would use basswood for the stringers....
Sagitarrius A-Star.jpg
 
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I only bumped this thread yesterday by accident. But since we're back...

I didn't get the BT-60 prototype built for NYPOWER, but I did get a quick and dirty one built over the weekend, which I'll swing test. If it passes that, I'll give it a test flight next week.

If the prototype test flight is successful, I'll move on to a three inch version with a 38 mm motor mount. A Build thread would would be certainly be involved.
One method of using Gas Dynamic Stabilization. I'm working on a Polaris A3 missile that using an alternate method...
GDS is certainly cool, but not what I'm trying for. The point isn't just to go finless, it's to test the specific idea of a ring tail and boat tail that overlap. Anything else, while all well and good, is off the mark.
 
Inspired by the above, and many other intersecting ring fins such as this, I wonder about truncated tube fins. Sort of like "What if ring fins actually intersected the body tube?" Here are some way less than half baked possibilities for aft views of what I'm talking about. I like the last one best, but I'm not sure if there's enough open space in the partial rings to make it stable. (Well, stable without an ungainly amount of nose weight; I'm confident the CP will be shifted aft somewhat.) RS allows for tube fins, but with the tubes partially buried in the body I doubt it will calculate and simulate correctly. I'd have to build and test.
1629896792392.png
1629896864307.png
1629896936108.png
 
Inspired by the above, and many other intersecting ring fins such as this, I wonder about truncated tube fins. Sort of like "What if ring fins actually intersected the body tube?" Here are some way less than half baked possibilities for aft views of what I'm talking about. I like the last one best, but I'm not sure if there's enough open space in the partial rings to make it stable. (Well, stable without an ungainly amount of nose weight; I'm confident the CP will be shifted aft somewhat.) RS allows for tube fins, but with the tubes partially buried in the body I doubt it will calculate and simulate correctly. I'd have to build and test.
View attachment 479178
View attachment 479179
View attachment 479180
I like the concept, but...

I think these types of designs might run into the boundary layer problem you can get with flat fins that have a short span. If the fin doesn’t get out into clear air, it doesn’t have as much effect. The rule of thumb I’ve seen for flat fins is that span should be minimum 1x body tube diameter. The top one would probably work for that, the bottom one probably not.
 
Yes!!

FWIW, my experience has been that area is the key. It must be at least equal to what a normal fin area would be. Also, my experience has been that about 5/8" clearance between ring and tube is sufficient.

But... isn't that experience based on ring fins, not tube fins?
 
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