Thor DSV-2J Program 437 ASAT (1:35 Scale)

[Project_Gemini]

Project Status: Concept Phase
Updated: 20180217

After a 21 year break in rocketry I have officially started my first scratch build. This is going to be a learning experience more than anything else. There will be many techniques used that I have never tried. I have decided that my first scratch build will be a 1:35 scale United States Air Force (USAF) Thor DSV-2J Program 437 ASAT. From 1966 to 1970 my grandfather was stationed, with the USAF, at Vandenburg A.F.B. During this time he would be flown to Johnson Atoll to work on a top secret nuclear anti-satellite weapon system known as the Thor DSV-2J Program 437 ASAT. This is the inspiration for building a scale model. I will be attempting to build the Thor DSV-2J Program 437 that can also be fitted with a Thor DSV-2J Program 437AP nosecone. I will not be attempting the Thor DSV-2J Program 437 HAP because there is not much information on it. This thread will include history of the program, build progress, questions, and much more. Please feel free to give me your feedback and criticism, that is the only why I will get better.

History:
Thor DSV-2 Wiki: https://en.wikipedia.org/wiki/Thor_DSV-2
Program 437 Wiki: https://en.wikipedia.org/wiki/Program_437
Johnson Atoll Wiki: https://en.wikipedia.org/wiki/Johnston_Atoll
Thor Space Launch Support: https://www.spacelaunchreport.com/thorflew.html
Gunter's Space Page: https://space.skyrocket.de/doc_lau_det/thor-dsv2j.htm
Visual Satellite Observer's Homepage: https://www.satobs.org/Program437AP/Program437AP.html

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20180217:
Attached OpenRocket file of the Thor DSV-2J Program 437 and Thor DSV-2J Program 437AP for review by members for recommendations.

 

[Project_Gemini]

I am requesting members to review the OpenRocket files attached to the OP. Please review and provide comments, recommendations, and feedback. Any assistance would be greatly apprexiated.

 

[Project_Gemini]

Has anyone taken a look at the files and come up any recommendations. Any assistance would be greatly appreciated.

 

[T-Rex]

I just gave them a look for you. I have some concerns.

Stability: As shown both models will most likely be doing cartwheels. The generally accepted minimum stability margin is 1 caliber.

Lexan surface mounted fins: Lexan is notoriously difficult to glue. If it were me, I would make them through the wall, then key them with a couple pieces of dowel on the inner wall of the tube. The dowels would need to be sanded to conform to the arc of the inner wall.

Parachute: needs to be bigger: The generally accepted standard for decent rate is a maximum of 20ft/sec. With the lexan fins, slower would be better. Don't forget to include a shock cord.

Your OR model has no couplers or bulk heads: Where does the model break for the chute to eject? if the nosecone ejects, how are you keeping it in place during flight, yet allowing it to eject from a tapered tube?

 

[Project_Gemini]

I just gave them a look for you. I have some concerns.

Stability: As shown both models will most likely be doing cartwheels. The generally accepted minimum stability margin is 1 caliber.
Thank you for the lesson on SM. I was under the assumption that as long as the CG was ahead of the CP it would be functional. The sim seemed like it would do fine. I will work on getting the SM to the 1 caliber margin.

Lexan surface mounted fins: Lexan is notoriously difficult to glue. If it were me, I would make them through the wall, then key them with a couple pieces of dowel on the inner wall of the tube. The dowels would need to be sanded to conform to the arc of the inner wall.
This is a great recommendation. Unfortunately, I do not know how to represent this using OpenRocket. I will research this more and figure out how to represent this in the design.

Parachute: needs to be bigger: The generally accepted standard for decent rate is a maximum of 20ft/sec. With the lexan fins, slower would be better. Don't forget to include a shock cord.
I will work on getting the decent rate to a max of 20fps.

Your OR model has no couplers or bulk heads: Where does the model break for the chute to eject? if the nosecone ejects, how are you keeping it in place during flight, yet allowing it to eject from a tapered tube?
I do not know which one you are referring to when you a saying OR model, I assume it is the 437AP. If this is the case the three top pieces are all the custom nosecone. I did not know how to represent this on the model as one solid piece of basswood.

I want to thank you for reviewing he files. I have added my responses in red. Please let me know if I represented you responses correctly.

 

[T-Rex]

I want to thank you for reviewing he files. I have added my responses in red. Please let me know if I represented you responses correctly.

Yes, you did well.
My statement about the nose cone, applies to both. You end your nose cone at a "Modified tube" that appears to be tapered like a transition. Is the 'straight' shoulder of your nosecone sliding into a tapered tube? If so it seems like it would be wobbly. While you don't need to show it in the file, you may need to add a ring of tube for the nose cone shoulder to slide into.
You have several sections of tube, modified to different tapers. You will need to add couplers at the joints to hold them together. Couplers can add a good bit of weight.
There is a coupling button, but it assumes the coupling to be a cylinder, not a cylinder on one end and a taper on the other. I don't think the taper will be an issue, but you need to account for the added weight.

Just add tabs to your fins, don't worry too much about the dowels in your OR file. If they end up being a significant weight, add them as a mass at the correct axial position,but don't worry about radial position.