ConeFin design

[Long_Gone]

Had this Idea for awhile just got some time to sim it out. Haven't come across any that I can find. There WILL be a body tube to go to the centering ring that is in the aft end of the transition (AKA Cone Fin), I just could not make OR do that! Everything checks out and I have the parts and motors. Funny thing someone bought me these mini motors and I have two Designers kits around so I figured it would be rather low cost experiment.



LG~

 

[neil_w]

There WILL be a body tube to go to the centering ring that is in the aft end of the transition (AKA Cone Fin), I just could not make OR do that!

1) Use an inner tube
2) Rockets of this style have definitely been done.

 

[GlenP]

Another similar design for comparison:

https://modelrocketbuilding.blogspot.com/2011/10/centuri-finless-rocket-plans-from-jim.html?m=1

 

[Long_Gone]

Interesting I came with the almost exact design Idea I like the launch lug inside of the cone also for alignment.

 

[OverTheTop]

It has been done in some missiles and sounding rockets I think. Examples escape me currently though. Works quite predictably in the supersonic region IIRC, and that's why they used to do it in the early days. Easy to prove mathematically, compared to other things anyway. Double-diamond airfoil was in the same boat.

 

[kuririn]

A few more:
Rogue Aerospace Deep Surface Probe.
DSP.pdf (rocketshoppe.com)
NewWay Sky Spike:


Fliskits MX Saturn V

 

[Long_Gone]

Nice never saw those models on the farm when I was younger. I only saw a few Estes rockets. Now we have rhe internet and advanced scientific computer modeling we can do more than we could back 35-40 years ago.
LG~

 

[Long_Gone]

I am still building it because I have the materials and it looks fun.

LG~

 

[Cape Byron]

The Centuri Finless is fun to clone and flies well. I did have a plan, but it isn't to hand. (L.O.S.T.)

There was another, I think, Centuri design that used just a series of maybe five centering rings with a space between. I have one built here somewhere...

Sorry, the office has become a crowded area since the flood. I can barely find the floor.

 

[lakeroadster]

I am still building it because I have the materials and it looks fun.

LG~

It's a cool idea. Build it and let us know how it turns out.

New designs, that have never been done before, are rarer than hens teeth. But don't let that stop you!

 

[waltr]

Yep, I have one for 13mm motors. Flies very well.

Neil_n said how to do design in OR.
BT to Transition (cone). Then inner tube for MM.

 

[Long_Gone]

I tried but the planets were not aligned.

 

[lakeroadster]

I tried but the planets were not aligned.

Nice design Long Gone. I added the "inner tube" motor tube. Also made the streamer longer to drop the ground hit speed.

 

[Charles_McG]

I've built two of the same size (BT60) and a similar design to what's pictured. The paper tube/cone version flew on a C11 and was stable-ish. It corkscrewed a bit. I suspect that it's got a low amount of corrective force at low speeds.

The fiberglass with printed cone flew great on F motors - as the upper stage of Nike/Recruit and Terrier Recruit sounding rockets.

https://www.rocketryforum.com/media/nike-recruit-jpg.347778/

 

[Mugs914]

It should fly pretty well, maybe with a bit of difference in stability between boost and coast phases.

I did a bunch of cone rockets many years ago. They were semi-scale Sprint missiles. Pretty good flyers!

The one remaining...

 

[Long_Gone]

Nice

 

[Sandy H.]

Had this Idea for awhile just got some time to sim it out. Haven't come across any that I can find. There WILL be a body tube to go to the centering ring that is in the aft end of the transition (AKA Cone Fin), I just could not make OR do that! Everything checks out and I have the parts and motors. Funny thing someone bought me these mini motors and I have two Designers kits around so I figured it would be rather low cost experiment.
View attachment 513726
View attachment 513728

LG~

I like it. As others have said, even if it (or a variation) has been done, no reason not to do it yourself. In this case, prior work just indicates you're going to have a good looking, nice flying rocket.

Personally, I hated rolling paper shrouds in the past. NeilW is great at it and uses the technique often. He and I dialoged via email about it and he got me to try the 'Super Shroud' technique. Apogee newsletter 349 talks about it, but it might also be posted in other places, as I believe the article was a user submission.

Anyway, I did it the 'regular' way with a single layer template, then did the Super Shroud method and liked it a bit better. I iterated a few different methods that I thought might work for me and eventually got one that I feel like worked 100% of the time, no matter how bad your (i.e. me, not you) modelling skills are. Regretfully, it worked practically flawlessly for 'high taper' shrouds (i.e. maybe 5-10 deg) but did not work for squatty shrouds (i.e. 20-45 deg+) at all - total failure. I abandoned the method, but do have a template generator spreadsheet that can give the parameters to make a strong and easy to make paper shroud. Your shroud looks like it would be successfully made, as the taper looks pretty aggressive.

I'm not sure if that was your plan for making the cone, but if you're not getting the results you want, PM me and I can run numbers and send you a template to try as an experiment. It would be for a 3-layer thick card stock shroud, most likely, as that's how I got the best results.

Sandy.

 

[cerving]

I always thought that using the S2-S3 transition on a Saturn V could work in a two-stage configuration without any additional fins, with the S3 and the transition being the second stage. My 50th anniversary Saturn V is collecting dust... time to get it out and give it a try.

 

[Long_Gone]

I like it. As others have said, even if it (or a variation) has been done, no reason not to do it yourself. In this case, prior work just indicates you're going to have a good looking, nice flying rocket.

Personally, I hated rolling paper shrouds in the past. NeilW is great at it and uses the technique often. He and I dialoged via email about it and he got me to try the 'Super Shroud' technique. Apogee newsletter 349 talks about it, but it might also be posted in other places, as I believe the article was a user submission.

Anyway, I did it the 'regular' way with a single layer template, then did the Super Shroud method and liked it a bit better. I iterated a few different methods that I thought might work for me and eventually got one that I feel like worked 100% of the time, no matter how bad your (i.e. me, not you) modelling skills are. Regretfully, it worked practically flawlessly for 'high taper' shrouds (i.e. maybe 5-10 deg) but did not work for squatty shrouds (i.e. 20-45 deg+) at all - total failure. I abandoned the method, but do have a template generator spreadsheet that can give the parameters to make a strong and easy to make paper shroud. Your shroud looks like it would be successfully made, as the taper looks pretty aggressive.

I'm not sure if that was your plan for making the cone, but if you're not getting the results you want, PM me and I can run numbers and send you a template to try as an experiment. It would be for a 3-layer thick card stock shroud, most likely, as that's how I got the best results.

Sandy.

Roger!

 

[Cape Byron]

There was another, I think, Centuri design that used just a series of maybe five centering rings with a space between. I have one built here somewhere...

Found it! Okay, although it sports an Estes decal I'm sure this was a Centuri design. 21" (53.34 cm) long including the nose cone. BT-50 tube. Flies well on Bs, Cs overwhelm it a little. We have been skywriting with this one on a C6-3...

 

[Long_Gone]

Found it! Okay, although it sports an Estes decal I'm sure this was a Centuri design. 21" (53.34 cm) long including the nose cone. BT-50 tube. Flies well on Bs, Cs overwhelm it a little. We have been skywriting with this one on a C6-3...

View attachment 513995

So that just has those centering rings?

 

[Cape Byron]

So that just has those centering rings?

Yep, just relies on drag for stabilisation.

 

[BigMacDaddy]

If you trust OR's calculation of the weight of 3D printed parts (PLA) then you should even be able to 3D print the rear transition (heavier) and have a stable rocket.

 

[lakeroadster]

Moved Here to minimize thread driftage..

 

[GlenP]

Found it! Okay, although it sports an Estes decal I'm sure this was a Centuri design. 21" (53.34 cm) long including the nose cone. BT-50 tube. Flies well on Bs, Cs overwhelm it a little. We have been skywriting with this one on a C6-3...

View attachment 513995

Very cool, too cool for spool!

I thought I had seen it all, but that is a new one for me.

I wonder how much you can reduce drag by adding some vent holes or notches to those before you lose all the stability, kind of like making them into alternating slots as in a baffle to reduce some of the drag but still be stable? Probably most of the stability comes from the base drag of the most-aft largest diameter spool, the other smaller discs in front of that one are more cosmetic and make a small contribution but likely not totally essential for stability here I think. Very interesting and thought provoking design, this is inspiring me to come up with a slight variation on the theme, thanks for sharing!

 

[dhbarr]

Very cool, too cool for spool!

I thought I had seen it all, but that is a new one for me.

I wonder how much you can reduce drag by adding some vent holes or notches to those before you lose all the stability, kind of like making them into alternating slots as in a baffle to reduce some of the drag but still be stable? Probably most of the stability comes from the base drag of the most-aft largest diameter spool, the other smaller discs in front of that one are more cosmetic and make a small contribution but likely not totally essential for stability here I think. Very interesting and thought provoking design, this is inspiring me to come up with a slight variation on the theme, thanks for sharing!

Should be able to make one spin with various gaps and offsets.

 

[lakeroadster]

Moved HERE to minimize thread driftage..

 

[Long_Gone]

OMFG these cones this small size are a Mother@#$%^&r to make!!!!!!

 

[Sandy H.]

OMFG these cones this small size are a Mother@#$%^&r to make!!!!!!

As mentioned in a post a bit above, I've got a method that might make !#$^%& turn to 'ahhhh' on certain types of shrouds. It is absolutely based on other people's work and is at most an incremental improvement, but the super shroud method seems to be 80% of it IMO and my method more of an iteration at best. Having said that, if you tell me the dimensions you're working with, I can draw up the shrouds, give a brief description and send you a pdf you can print to try. I will also need to know the cardstock thickness you have on hand to print, as the method refines the geometry of the patterns and thicker or thinner paper will render it useless.

The versions I laser cut work surprisingly fast, IMO. If you want to try a version that you print and cut and a version I laser cut to see if you get different results, I'm in. Just PM me the info and I'll mail something out for you to try.

Sandy.

 

[tsmith1315]

I've been testing little frames to support the shroud. They're a bit fiddly until you get them secured with a dot of CA, but pretty stout after that.

These are for a 29mm tube, one from heavy mat and one from heavy paper, maybe 65lb cardstock.