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Cone stabilized finless rockets
#1
Over at http://www.oldrocketforum.com/showthread.php?t=15334  I posted about my new cone stabilized finless rocket, the Rxiiiab, and there's mention of some other similar rockets: the Arcturus and Candlestick from ca. 1970 Model Rocketry, a design from a ca. 1970 American Rocketeer, the SAI Vulcan, the Hot Rod Bell Bottom, the FlisKits Mighty Saturn V, and the Odd'l Rockets Flare. I wrote more about some of these at https://richsrockets.wordpress.com/2015/...-thoughts/ , and J. Steven York  had some interesting comments here https://plus.google.com/1182910563173591...9GEdBnsJVd 

Anyone else have insights? Particularly about stability. If the Barrowman CP is relevant for these designs, then it seems the ca. 1970 ones all had significantly more nose weight than is needed — even if you don't include an adjustment for base vortex drag, which would pull the CP even further back. On the other hand, York says "I've heard from some people the cone stabilized rockets are very susceptible to angle-of-attack problems, and can seem stable until something (wind, off-center or deflected thrust, ...) kicks them off straight and true. Then they go all to hell."

The Rxiiiab seems quite nose heavy, tending to impale itself lawn dart style even after deploying the streamer, and I'd like to try reducing the nose weight. But I'm already using less nose weight than one would probably expect based on the ca. 1970 designs, and York's comments suggest it may be best not to go there. Any thoughts?
Rich Holmes
Camillus, NY
Secretary / newsletter editor
Syracuse Rocket Club

http://richsrockets.wordpress.com
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#2
It will be interesting to see the final consensus. I have only built one cone stabilized rocket that wasn't a true cone or basically a saucer. It is 10.5mm minimum diameter to fly on the old Apogee motors. I don't have a sim and will have to find it, but I don't remember adding any nose weight other than using a resin cone. It is a foot long or so as I remember so it has a large l/d.

Issues with dynamic stability wouldn't surprise me. I'll have to sim mine and determine the thrust to weight ratio for the B2's that I flew it on.

I'm not sure my rocket will provide a lot of insight. I made a quick Rocksim model, which is attached. I couldn't load a motor as Rocksim no longer has the 10.5mm motors loaded. Luckily I had one on hand to check the loaded CG and I can still find the specs online.  The loaded CG still yields a stability margin of over 6. By my calculation, the thrust to weight is over 7 based on the average thrust and something crazy like 22 for the peak.

BTW, the Barrowman and Rocksim comp methods yield the same CP...something I've never encountered before. I don't think you safely can count base drag on typical rockets even with the cone base. Bruce Levinson's base drag stuff were all predicated on short stubby rockets.

It probably applies here:


Attached Files Thumbnail(s)
       
Member of MDRA, NAR and NARHAMS;
Level-2 certified but mostly fly G and under;
Volunteer compiler of manufacturer's news for ROCKETS Magazine.
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#3
Photo 
I can give you info on the BellBottom.n
Specifications:
Length 11.25”
Width  .544
Cone Span 2”
Fly it on just about any 10mm motor from the big "E".

Used a cast resin Cone.  Definately heavyer than balsa.  
Notes:  I am a Cone/Shroud tail junkie...  I have launched all manner of versions of this scaled for 18mm motors and (my personal favorite) 24mm motors.

Ahhhh... cone rockets with smokey reloads....  Nice smoke rings!  

Now I never fly these of any scale in anything but the Calmest days.  They are prone to weather cock in a bad way in a brezeze.  Just think Glider weather..  A good Glider day is a good Cone Tail day.
Mine are oldies but goodies, not designed with any confuser programs.  You kinda have me wondering what happens if I try them in a sim program...  Hmmm?
[img]<a href=[/img][Image: bell.jpg]" />
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#4
That is COOL!


Bill Clune L3 | NAR#88583
Been a launch Director
Founded a Club
MARS Club|SRC|MDRA - Forever
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#5
Apparently blue is the proper color.

[Image: img_6954.jpg]
Rich Holmes
Camillus, NY
Secretary / newsletter editor
Syracuse Rocket Club

http://richsrockets.wordpress.com
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#6
Found my Larger ConeTail while packing up to move.
  24mm motor mount.  Also Blue.  As I took another look at this one I think the improvements for the next ConeTail will be a smaller diameter cone.  and a stronger/ hardened materiel for cone shroud.  Shroud on this one is Cardstock.  Possibly I will coat the next one in light epoxy, if I think I can get it  light enough.

[Image: 20151006_145612%20small.jpg]
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#7
(09-20-2015, 12:55 PM)HotRodRockets Wrote: "I can give you info on the BellBottom.
Specifications:
Length 11.25”
Width  .544
Cone Span 2”
Fly it on just about any 10mm motor from the big "E".

Used a cast resin Cone.  Definately heavyer than balsa.  
Now I never fly these of any scale in anything but the Calmest days.  They are prone to weather cock in a bad way in a breeze.  Just think Glider weather..  A good Glider day is a good Cone Tail day."
________________________________________________________________________________________________________________________

The Bell Bottom is a favorite of mine. Perfect small field flyer.
My kit had ta balsa nose cone.

Question: Where did you find that ribbed streamer material used in the kit?
Hans "Chris" Michielssen
Old/New NAR # 19086 SR
www.modelrocketbuilding.blogspot.com

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#8
(10-17-2015, 10:18 AM)hcmbanjo Wrote:
(09-20-2015, 12:55 PM)HotRodRockets Wrote: "I can give you info on the BellBottom.
Specifications:
Length 11.25”
Width  .544
Cone Span 2”
Fly it on just about any 10mm motor from the big "E".

Used a cast resin Cone.  Definately heavyer than balsa.  
Now I never fly these of any scale in anything but the Calmest days.  They are prone to weather cock in a bad way in a breeze.  Just think Glider weather..  A good Glider day is a good Cone Tail day."
________________________________________________________________________________________________________________________

The Bell Bottom is a favorite of mine. Perfect small field flyer.
My kit had ta balsa nose cone.

Question: Where did you find that ribbed streamer material used in the kit?

Yup.  Most kits have Balsa Bt-5 cone.  works much better / flies higher.  My original personal and the first batch where resin.   (That's infofor all you collector types)

- Ribbed streamers....  Well  here's more insider info: Littel old Special efects majic there!
 If it's real Shiny Sparkely mylar it's from the party store Gift wrapping.  Makes perfect streamers.  Bright and reflective in the air and on the ground in the tall grass!
-Crimping is done with a paper crimper.   Make it by the mile! 

http://www.joann.com/fiskars-paper-crimper/4121422.html
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