Dual deploy on HoJo type NC / airframes

[Tim51]

Hi all
Quick question - for an Honest John type nc/airframe combination, where the NC dia is wider than the aiframe, is there an optimum location for an AV bay with static ports? For example, my understanding is that static ports should not be placed immediately behind a reducing transition. Is it ok to place them further back, and if so, how many calibers?
Thanks

 

[3stoogesrocketry]

Virtually all modern electronics are not prone to mach shock wave interference like the old blacksky units . I have rockets that house the electronics in the NC with the vent about 1 inch above the base of the cone.

 

[Tim51]

Virtually all modern electronics are not prone to mach shock wave interference like the old blacksky units . I have rockets that house the electronics in the NC with the vent about 1 inch above the base of the cone.

Thanks. In your view/experience is placing the altimeter in the NC the only option in HoJo type designs, or could the aiframe tube be used?

 

[Speaknoevil]

Or you could make the center of the nosecone the dual-deploy break point like I did in this build (see post #16): https://www.rocketryforum.com/threads/honest-john-fin-profiling-after-the-fact.61860/. Inside the cone is a normal av-bay as below.

 

[Tim51]

Thanks @Speaknoevil that looks great - even though I did a search I hadn't seen your Honest John build before - really nicely done.

 

[3stoogesrocketry]

Thanks. In your view/experience is placing the altimeter in the NC the only option in HoJo type designs, or could the aiframe tube be used?

Speaknoevil laid out a very nice option. You could also have the Altimeter(s) in the BT if you made it "zipperless" and kick the fin can off as I did with the old Public Enemy HOJO. I used to "compete" in the bowling ball launching , and wanted to carry the concept into the hojo as a goof . I found That a standard size soft ball fits perfectly inside of a 4 inch NC with the bottom cut off . That and s 24 inch chute made a fun main deploy. The last flight I threw a I435 in it and the decel after burnout shot the soft ball turned cannon ball right up and blew the mains at 500 mph give or take.