First two-stage HPR project

[Fearoflightning]

Hello,

As the title states, I have decided to build a two-stage high powered rocket as something to kind of transition into my level three cert.

So here's what I have in mind:

The sustainer will be either 3" or 2.6" (depending on what transitions for the interstage coupler I can find.... I prefer 2.6) with a 38mm mmt. All bluetube with G10 fins. It will be standard dual deploy with likely a stratologger CF as the altimeter. I will have an electronics bay between the fins to hold motor ignition electronics, which I have not decided on. Suggestions are welcome

The booster will be either 3" or 4" (Again depending on transitions... 3" is preferred.) with a 54mm mmt. Bluetube with G10 fins, standard dual deploy. (I have toyed around with the idea of using a jolly logic with a single compartment...) I want to be able to pretty easily fly this section on it's own as well with the addition of a nosecone.

This brings me to the interstage coupler. I plan on fitting an AV-bay with the necessary electronics (suggestions welcome) inside of the coupler section. I will have small charge separate the stages. There's too much chance relying on drag separation. I will have a coupler fit inside the sustainer and butt up against a recessed (by at least an airframe caliber) centering ring. This seems to be a universally agreed upon method, but if not, please offer suggestions

I will be posting all progress here, but alas, I am a poor engineering student, so progress will likely be pretty slow....

I'll have an openrocket file/screenshot posted within the next few days of my ideal design.

I am open to any suggestions, thoughts, ideas, and examples!

Thanks!

 

[Bat-mite]

op:

Looking forward to it.

 

[Titan II]

Have you considered putting the electronics to start the second stage motor in the e-bay along with your Stratologger? The wires run down the inside of the airframe and go through a tube to below the bottom centering ring. You just twist and tape the ignition wires together below the e-bay. They easily come apart during separation.

If you have not seen it, here is a recent thread that may be of interest:

https://www.rocketryforum.com/showthread.php?135498-2-stage-coupler-assistance

 

[BDB]

I'm hoping to build two HPR two-stage rockets over the winter, so I'd love to see what you have in mind. I've posted this pic elsewhere on TRF, but this is as far as one of the two projects has gotten thus far. It's not shown in the picture but I have a 3" FG nosecone an a length of 54 mm coupler that I am planning to use to make my interstage transition/coupler. 2017 will be the year of the HPR two-stage!

 

[Fearoflightning]

Have you considered putting the electronics to start the second stage motor in the e-bay along with your Stratologger? The wires run down the inside of the airframe and go through a tube to below the bottom centering ring. You just twist and tape the ignition wires together below the e-bay. They easily come apart during separation.

If you have not seen it, here is a recent thread that may be of interest:

https://www.rocketryforum.com/showthr...ler-assistance

I like that idea, it saves a bit of work and complication. It also allows the sustainer to have less area between the mmt and airframe.

2017 will be the year of the HPR two-stage!

Yes!!!

So I decided to go with a 54mm sustainer and a 75mm booster. Each is stable with the largest motors I can fit. With a two second delay between separation and sustainer ignition it will do mach 2. I don't think I'll push it that hard though.... I'd like to hear some thoughts on whether bluetube and 1/16 (or 3/32) G10 can take mach 2.

The booster, with the addition of a few pieces, will fly on it's own as well.



The interstage coupler will be made of an extended 54mm coupler held to a 75mm switch bandnd coupler by two centering rings. The actual transition will be 3d printed and possibly glassed over. Probably not though, since it's only there for aerodynamics.

Any suggestions for staging electronics in the interstage coupler and sustainer AV bay?

This is looking like a lot of fun/work/expense, I can't wait to get started