Doubt: can I rocket have a decreasing diameter?

[Eduardo]

Hello everyboy,
I would like to know if would it be possible to a rocket have an inverse silhouette, a decreasing diameter: the nosecone bigger than the last part of body tube.
Follow an image as an ilustration.
Thanks.

 

[rharshberger]

Yes, the Estes Ventris, Magnum Payloader, and Magnum II and several others are examples of commercial kits, FAI Parachute and Streamer Duration models are yet more extreme versions.

 

[XrayLizard]

Photo of a photo of an egglofter lol

 

[neil_w]

Estes X-ray, introduced in 1965:

 

[Steven]

When mine lawn darts.

 

[GlenP]

This body tube goes down from 18mm to 13mm, one long transition after the nose cone shoulder portion.
(this is not the actual Astron SPRINT, but a kit bash modified version.)


https://www.rocketryforum.com/attachments/dsc_8850-1-jpg.428958/

and another one of my favorites, the Centuri Snipe Hunter

https://www.rocketryforum.com/threads/centuri-snipe-hunter-gallery.25290/

 

[prfesser]

Also the Farside-X, that had a BT-50 airframe and a BT-60 payload tube.

The Camroc Carrier (see https://www.spacemodeling.org/jimz/eirp.htm, #60) was a neat little package that made it possible to take photos with a single-stage rocket; previously a two-stage rocket was recommended as the vehicle. It had a 24 mm airframe and the Camroc itself as the payload, about 38 mm diameter if memory serves.

Best -- Terry

 

[mbeels]

And the Estes Eggspress/Scrambler:

 

[Funkworks]

Some versions of the Titan, Falcon 9, and New Shepard rockets, and the The Honest John.

 

[mbeels]

Tom's Yellow Submarine (on a "P" motor):

 

[BABAR]

Go big or go home!

 

[stantonjtroy]

So the short answer to your question, as evidenced here, is "Yes", it's possible.

 

[bill_s]

5.5" diameter, simmed like 2.5", flew almost like it too. Also rear ejection so it came down nose first, however super cramped to pack and that was its undoing. No pictures after final paint job.

Note, any reducing transition in the back half of the rocket reduces stability, must sim, the CG in this rocket is just behind the front rail guide.

 

[Michael L]

I was going to mention the Falcon 9 and Falcon Heavy from SpaceX but they require thrust vectoring similar to what Joe Barnard is experimenting with. Fun project if the larger motors ever become available again

 

[CoachSteve]

 

[CoachSteve]

 

[CoachSteve]

4" down to 24MM - flies awesome on F39s

 

[hermanjc]

As basically demonstrated by various other posts above, you can fly just about any shape Just need to make sure you have your CG far enough forward of the CP. Looks like you plan to have fins on the tail, so just size them appropriately. My Falcon Heavy Center Core flies straight and true, just needed fins (harder to see in these pictures because I used clear poly carbonate).

 

[rocketace]

54mm at its widest down to 29mm.

 

[ThirstyBarbarian]

So the answer is yes you can do it, and there are lots of examples. The main things you need to make it work are standoffs for your launch lugs or rail buttons so the wide part can clear the rod or rail.

And you need to figure out where you are going to separate the rocket and deploy the parachute. If you are going to have the chute in the narrow tube, you can have a solid transition piece and everything forward of that can be glued together as a single piece, like one big nose cone. Or if you are going to have the chute in the wider forward tube, then the transition can’t be solid, and you need a tube to pass the ejection gasses into the forward section.

Just from looking at your image of the Vanguardist, my gut feeling is the fins need to be bigger to move the CP aft.

Good luck with your project!

 

[BABAR]

Go wild!

https://www.spacemodeling.org/jimz/eirp/eirp_49.pdf

 

[Funkworks]

Ariane 1 to 4, kind of.

 

[OverTheTop]

Half-scale Apache



M1.05 on a CTI M840.

 

[BDB]

View attachment 435563

Go big or go home!

Is that nosecone a float from a toilet tank?!

 

[GlenP]

Is that nosecone a float from a toilet tank?!

Kind of a striking resemblance to this kit

https://www.rocketarium.com/Rockets/Tank-Buster
but I like the tank float version better.

 

[BABAR]

Is that nosecone a float from a toilet tank?!

Yup.

Flew arrow straight on D12

 

[jqavins]

Some versions of the Titan, Falcon 9, and New Shepard rockets, and the The Honest John.

And Atlas 5 5x1 (521 pictured).

And you need to figure out where you are going to separate the rocket and deploy the parachute. If you are going to have the chute in the narrow tube, you can have a solid transition piece and everything forward of that can be glued together as a single piece, like one big nose cone.

Another option is to break for deployment below the first transition (as TB said) but friction fit one of the joints above to allow for inserting a payload. You've probably noticed that many of the models and all of the "real" rocket examples cited so far have the larger section for the carrying of payloads.

 

[Eduardo]

Thanks so much everybody for this lot of material you've sent me

 

[Gonzo]

Dual deploy setup. 3” booster section with 4” payload fairing