Single Scoupe Stable, Double Scoupe not so much

Not sure with these funky off center cylindrical slanted ring fins this rocket is simulatable anyway.

In any case, the Single Scoupe is a beautiful flyer on a Quest A6-4. Double Scoupe with C6-0 to A8-3 was a bit more, well, entertaining.

If I mark the CG for Single Scoupe (fully loaded with A6-4)

and then add the booster stage with C6-0, then add enough nose weight to bring the CG forward to the same as the stable Single Scoupe, should this two stage then be stable?

So long as the CG is in the same place, yes, it should be stable. The extra fin on the booster will actually make it a little overstable- which is exactly the problem you might have with the sustainer. If it has enough nose weight to keep the CG stationary after adding the weight of the booster, the sustainer could weathercock severely. I would recommend putting the CG with the booster a little behind the CG without the booster, though without knowing the effect the booster fin has on the CP, you want to err well on the side of caution.
Of course, even if the sustainer does weathercock severely, it may not be a problem if you have enough altitude. When I flew my scratch-built two-stager, the sustainer was traveling horizontally a second or two after staging, but it recovered perfectly because it had traveled high enough on just the first stage.
Good luck!

The rocket is being stabilised by one tube fin. What effect will doubling the length of that tube fin have on the CP? As I understand it, tube fins may become less efficient if they are longer.

adrian said:

The rocket is being stabilised by one tube fin. What effect will doubling the length of that tube fin have on the CP? As I understand it, tube fins may become less efficient if they are longer.

Click to expand...

That's a very good point. I had forgotten about that, and was relying on my knowledge of "regular" fins.
However, I think if you keep the CG constant, you might still be okay. As Uncle Vanya said in this post, (assuming he is correct) a tube fin is effective until it reaches the point where the length is three times the diameter. However, I don't know if it becomes less effective as it becomes longer, in which case keeping the CG constant may not be enough to ensure that it is stable.

I saw this illustration and immediately thought of @BABAR , check it out:



https://siamagazin.com/lockheeds-concept-ring-wing-airliner/
Search "Lockheed Ring Wing" for more articles.

mbeels said:

I saw this illustration and immediately thought of @BABAR , check it out:

View attachment 600035

https://siamagazin.com/lockheeds-concept-ring-wing-airliner/
Search "Lockheed Ring Wing" for more articles.

Click to expand...

too much craftsmanship for me. But @hornet driver , @neil_w , or @lakeroadster could easily pull it off!

My concern is that the booster stage may not tumble or glide slowly after separation. You could probably trim it to glide reasonably.

That looks like a crazy Midjourney creation, or maybe something from an unreleased Gerry Anderson project.

OK, ready for this??? If you build the booster stage 90 degrees off from the sustainer, it'll work. Right now you're trying to work with the look, and have the two sets of fins line up, which looks great, but the tube fin becomes too long to be effective, but if you rotate the lower stage to be 90 degress off, the two sets of fins work together and will make it stable (although less pleasing to the eye).

techrat said:

OK, ready for this??? If you build the booster stage 90 degrees off from the sustainer, it'll work. Right now you're trying to work with the look, and have the two sets of fins line up, which looks great, but the tube fin becomes too long to be effective, but if you rotate the lower stage to be 90 degress off, the two sets of fins work together and will make it stable (although less pleasing to the eye).

Click to expand...

Actually, the two stage works great as pictured.

https://www.rocketryforum.com/threa...n-glider-and-new-gyskelion.38883/#post-362599
See post 4

booster tumble recovers nicely. Even did it with a far longer sustainer which recovered by Back Slide.

It’s a surprisingly easy build. Balsa free!

BABAR said:

too much craftsmanship for me. But @hornet driver , @neil_w , or @lakeroadster could easily pull it off!

Click to expand...

Neat bird.... I'll add it to the build list.

And this guy actually flew (with a conventional tail)

mbeels said:

And this guy actually flew (with a conventional tail)

Click to expand...

That took some guts! I'm not sure I'd put my life on the line taking that into the air. For a model, it's all about "can it be done?" Practicality doesn't matter. For piloted aircraft, I guess people do things to get into the record books, like the worlds smallest manned plane and manned jet, but this design wouldn't break any records.

Drag too one sided, too asymmetrical, pushing the envelope too far?

Daddyisabar said:

Drag too one sided, too asymmetrical, pushing the envelope too far?

Click to expand...

I've done several of these, including the most recent NAR, flown as single and two stage. The always turn in a NET straight trajectory, although a variable amound of corkscrewing. DEFINITELY not good VideoCam birds. But they are reliable fliers, haven't had one go unstable yet.

Symmetry is FAR over-rated, much more important is ALIGNMENT. And perfect alignment is pretty easy to achieve in these., line up a straight line on the inside tube with a straight line on the outside tube and you're golden.

I have to admit, I was surprised when the two stage flew well, but it did.

this one might encourage @lakeroadster that his plan for post 11 is do-able.

https://www.rocketryforum.com/threads/spirit-of-america-or-does-1-3fnc-3ncf-3-engine-cluster.153732/

BABAR said:

Symmetry is FAR over-rated,

Click to expand...

Blohm & Voss would agree with you, check out their BV 141. Apparently it flew fine:

https://en.wikipedia.org/wiki/Blohm_&_Voss_BV_141

Does anyone know where I can get the wing pivot plans for the scissor wing transport?

49markt said:

Does anyone know where I can get the wing pivot plans for the scissor wing transport?

Click to expand...

http://www.spacemodeling.org/jimz/estes/est1265.pdf
also has been rereleased

https://jonrocket.com/shop/index.php?main_page=product_info&products_id=7695
there are other sources, can’t recall what company did the redo but someone will chime in.

in any case, I think there are at least two threads in last year of the build of the rerelease Which may help you, apparently it is a bit twicky.

lakeroadster said:

Neat bird.... I'll add it to the build list.

View attachment 600266View attachment 600270​

Click to expand...

Something you will like about the recovery, this bird will never land directly on the fin or ring. It will fall either straight tail first or if sideways with the ring and fin UP.

It‘s a nice feature for asymmetric fin models. The cost (or bonus, if you like the entertainment value) is they tend to corkscrew a bit on the way up. I think it’s kind of fun, but I may be a minority in that regard.

Looks like a Corkscrew (rocket).

If we are looking at asymmetry, don't forget the Rutan Boomerang


https://en.wikipedia.org/wiki/Rutan_Boomerang
http://stargazer2006.online.fr/aircraft/pages/boomerang.htm

BABAR said:

too much craftsmanship for me. But @hornet driver , @neil_w , or @lakeroadster could easily pull it off!

Click to expand...

Damn, I wish I would quit stopping by--Now I have to think about this one--It is doable, crazy, but doable--Oh lord , I'm being sucked in again !

hornet driver said:

Damn, I wish I would quit stopping by--Now I have to think about this one--It is doable, crazy, but doable--Oh lord , I'm being sucked in again !

Click to expand...

We'd love to have you back.

Remember,


https://www.aperfectworld.org/0428.html