2 fins and a nose cone...and it flies.

[sl98]

The recent Apogee Peak of Flight contained a free plan for a 2 fin spin stabilized rocket. The rocket is designed by Kevin Cronwell and is in issue 514. The rocket only requires 6 parts, which I had on hand. The longest part of the build was waiting for glue to dry. Total build time was about 1 hour. I was a little skeptical whether it would fly. I launched today on an A8-3 and it flew straight and true. I don't think I would use a larger motor because you may never find it again. This little guy earned its paint.

 

[mbeels]

Neat! That's a fun idea.

 

[kuririn]

Cool!
First thought: wonder if it can be upscaled?

 

[gna]

Nice! I saw that design, too, and thought about building one. I have everything but a coupling laying around here.

 

[sl98]

I have everything but a coupling laying around here.

If you have a shorter coupler, you could use a thrust ring and glue the shorter coupler above the thrust ring. You could also try one of the yellow tubes Estes provides for placing thrust rings as your coupler. It might be a little bit of a loose fit but a wrap of tissue paper and soaking in thin CA might make a good fit.

 

[BABAR]

Very cool!

Other stable two fin designs

@Flyfalcons
Guitar rocket (super cool)

https://www.rocketryforum.com/threa...c-n-roll-flying-v-guitar.134436/#post-1588660

Also

Lucky 7

https://www.rocketryforum.com/threads/stable-two-planar-fin-rocket-return-of-lucky-7.154443/

Or you can go with one fin

Corkscrew

https://www.rocketryforum.com/threads/tired-of-3-or-4-fnc-time-to-pull-out-the-corkscrew.38719/

Or no fins

Up Cup

https://www.rocketryforum.com/threads/styrofoam-cup-rocket-anybody-done-this.148007/#post-1814952

 

[gna]

The recent Apogee Peak of Flight contained a free plan for a 2 fin spin stabilized rocket. The rocket is designed by Kevin Cronwell and is in issue 514. The rocket only requires 6 parts, which I had on hand. The longest part of the build was waiting for glue to dry....

Just curious--they list 1/8 balsa. Did you use 1/8 or 3/32 balsa?

If you have a shorter coupler, you could use a thrust ring and glue the shorter coupler above the thrust ring. You could also try one of the yellow tubes Estes provides for placing thrust rings as your coupler. It might be a little bit of a loose fit but a wrap of tissue paper and soaking in thin CA might make a good fit.

I'll have to dig through the bin with all my parts and see what's in there. I looked the other day for BT20 and didn't see any couplings, but I wasn't really looking for them.

 

[sl98]

I did use 1/8 but it sure is overkill. I think 3/32 would be just fine. I would even try 1/16 basswood if I made another one.

 

[SDramstad]

Cool!
First thought: wonder if it can be upscaled?

Hmmmmmmmm..........

 

[Alan15578]

Cool!
First thought: wonder if it can be upscaled?

Certainly.

I had an old NACA report that explained it all, but I lost it. I think it dated back to the WWW I era. They wanted to stabilize dropped bombs with planar fins (two fins canted) because they could be packed and dropped more efficiently. NACA figured out how to size and cant the fins, but then fond that such stabilization was unsuitable because the bombs had a larger dispersion pattern. This type of stabilization was most often seen on the Parks water rockets. For sport rockets, it is just a novelty, but I still want to find the report number and the report itself. I think all the old NACA reports are available on line, but there are too many to search through.

 

[sl98]

Painted after maiden flight and made one fin black to make it easier to visualize the spin. You can see almost 1 full rotation in first two pictures as it is leaving the launch rod. Another perfect flight with an A8-3. Time to upscale.

 

[sl98]

Started a 223% upscale using BT-60. Fins are cut. Working on 24mm motor mount. Initially I was thinking rear deploy. I am going to try MM that ejects with a streamer and still breaks rocket in 2 for tumble recovery. If that doesn’t work a switch to rear deploy should be easy.

 

[gna]

Here’s mine:
I papered the fins for a bit more strength. Of course, there’s no green grass here, so it’ll be a while before it flies, or gets painted...

 

[sl98]

Ready to begin final assembly of "Big Cyg." Not pictured is 18" upper tube, PNC-60AH nose cone, kevlar, and steamer that will be attached to motor mount. The coupler serves as a thrust ring for the the motor mount. The nose block will be glued in about 1 1/2 inches from the bottom of the upper tube. First flight will be on a C11-3. The new C5-3 might be a good option too.

There is a lot of flexibility with this design. If it flies well, I could make another motor mount for 29mm. The set up will also make it easy to convert to rear deploy if the eject/tumble separation doesn't work or if it becomes too difficult to track MMT and rocket coming down separately.

 

[sl98]

Big Cyg is ready for primer and a first flight.

 

[sl98]

I took Big Cyg out for its first flight today along with original Cygnus. Big Cyg was loaded with a C11-3 and Cygnus was loaded with a B4-4. Big Cyg's flight was dramatic and cut short by a CATO.

I got some of the best CATO pictures I've ever taken. The flame coming out of the rocket looked larger that a H128. The motor mount was destroyed and the upper tube will have to be replaced. The fin can is fine. The repairs shouldn't take take that long.

No pics of Cygnus on a B4-4 because I wanted to focus my attention on tracking it. Cygnus shot off the pad laser straight. Nice deployment and tumble down.

I've noticed Cygnus likes to come in nose first. Fortunately the grass is still soft. For Big Cyg, I actually designed it to hopefully shake the nose cone free and tumble down in 3 pieces. After repairs, I will test this concept on Big Cyg.

 

[BABAR]

Wow!

There’s one to put in the Lift Off Gallery.

Or maybe start a Best CATO Gallery

 

[ebruce1361]

Has anyone ever built a one-fin rocket? I'm thinking of a spiral that wraps around the body so it behaves like a ring fin, but is one piece.

 

[lakeroadster]

Has anyone ever built a one-fin rocket? I'm thinking of a spiral that wraps around the body so it behaves like a ring fin, but is one piece.

Like a Dr. Evil's subterrenian drill... but it goes up, instead of down....

 

[ebruce1361]

Like a Dr. Evil's subterrenian drill... but it goes up, instead of down....

Kinda like that! I was thinking a bit longer though.

 

[dhbarr]

Kinda like that! I was thinking a bit longer though.View attachment 408099

Apogee Peak of Flight 220, pg 8

https://www.apogeerockets.com/education/downloads/Newsletter220.pdf

 

[sl98]

I took advantage of nice weather and an empty field to try Big Cyg again. This time, I used a D12-5. Lift off was straight and true for the first 20-30 feet (Pics 1-5). Then Big Cyg started to corkscrew (Pics 6-8). Ejection worked as planned. The rocket separated into two pieces to tumble down and the motor mount spit out and came down on 2 - 6 foot long streamers (actually 12 feet of streamer tied in the middle to the mount) (pics 9-10).

Apogee: 684 ft.
Max speed: 255.2 ft/s.
Time to Apogee: 7.68 sec

Original Cygnus had two flights on a A8-3 and B4-4. Perfect flights but no pictures.

 

[BABAR]

Nothing wrong with corkscrewing as long as net trajectory remains relatively vertical!
Makes for a neat smoke trail, and keeps altitude manageable for smaller fields and shorter walks.

 

[gna]

We had a social distance launch Saturday. I flew mine on an A8-3; it flew great.

The problem was, I lost track of it. I had a separation, but I did find the pieces. I will need to glue the the shock cord to the lower level on better.

 

[gna]

I repaired my Cygnus and painted it much like yours, orange with a black fin. Here it is on the rack:

It flies very well on an A8-3.

 

[GlenP]

These are easy enough to find, just posting the link here, as I was just looking it up, very cool design.

Could paint one side blue and the other side yellow and see if if looks green on the way up! Or blue and yellow barber pole stripes to hide the tube spirals, maybe?

Peak of Flight index:
https://www.apogeerockets.com/Peak-of-Flight?pof_list=archives&m=education
#514 - https://www.apogeerockets.com/Peak-of-Flight/Newsletter514
https://www.apogeerockets.com/education/downloads/Newsletter514.pdf 02/04/20 1.7 MB
Fillets in Model Rocketry
Cygnus Rocket Plan

EDIT - a cardstock model, variation on the theme:
https://www.rocketryforum.com/threads/inspired-by-cygnus-pof-514-plan.161787/#post-2043794

 

[Ronz Rocketz]

These are easy enough to find, just posting the link here, as I was just looking it up, very cool design.

Could paint one side blue and the other side yellow and see if if looks green on the way up! Or blue and yellow barber pole stripes to hide the tube spirals, maybe?

Peak of Flight index:
https://www.apogeerockets.com/Peak-of-Flight?pof_list=archives&m=education
#514 - https://www.apogeerockets.com/Peak-of-Flight/Newsletter514
https://www.apogeerockets.com/education/downloads/Newsletter514.pdf 02/04/20 1.7 MB
Fillets in Model Rocketry
Cygnus Rocket Plan

That’s a lot of uptodate reading.