Dual Deployment Variances - Design or Evolution?

When I began to research dual deployment on Google, I noticed some resources include diagrams where the drogue chute is in the lower half of the rocket, while others indicate that the drogue chute be placed in the upper half of the rocket. Is this a matter of the means/method by which a rocket is chosen to be separated (assuming on-board charges will be used in both cases)? Or, is this a matter evolution where I was looking at older diagrams where it was in the top half, and through advancement of knowledge, was realized to be more optimal if located in the bottom half?

Drogue in lower payload is usually normal, however the drogue has to be properly sized so that under drogue descent the two sections are in an inverted "V", so that when the main is deployed from the upper payload bay it is in clean air, preferably the fin can will be lower than the upper section.

Firstly, thanks for putting the question out to the hive mind!

In the interest of individuality, I am going to say have a look at what everyone else has done for ideas, but don't limit your thinking to following a particular path. There is a lot information out there and a lot of different ways of doing things. Materials and construction techniques evolve, as do the electronics and deployment methods. Rocket builds are also very individual, even with the same kit as a basis.

So, at the risk of being controversial, I suggest you look at the various techniques and variations that are out there. Then think about how it will work in your build. Make sure you work to your strengths and skills for the build to improve you chance of a positive outcome. So really think it through, figure out what you think should work (especially for off-nominal situations!) and then put it out to the collective mind to see what we think. Sometimes we don't know what we don't know when building something, and a design review is such a good part of a successful build and nothing to be too afraid of.

There are a lot of opinions out there on lots of things, including dual deploy. Treat any criticism as constructive, design what you think will work and make the build yours.

If you have any clever or different ideas don't be afraid to consider them either. If they won't work then drop them, else keep an open mind

Um, in conventional avbay-in-the-middle dual deploy the drogue is always in the lower section. I guess you could do it backwards (you wouldn't be able to use motor ejection as apogee backup) but I don't see any advantage.

There are lots of variants but have people ever tried what the OP was describing, and if so, why?

Drogue is in the middle to reduce the load on the sheer pins holding in the main.
Reverse the two chutes and see how hard it is to keep the main in at apogee.

One thing you can consider with any approach you might come up with is how will it perform in case of a high speed deployment. This happens, and the purpose of the recovery approach is to get the rocket down in one piece without putting people on the ground at risk. The conventional dual-deploy configuration, particularly with a zipperless couple, is designed to allow safe recovery even in the case of very high deployment speeds. When something comes out the top at high speed, bad things can happen.

Jim

To go along with what Jim said, separating in the middle helps to destabilize the stack and slow things down. If you pop the nose cone off a fairly stable rocket at high speed you may still get a ballistic descent if any part of the deployment sequence malfunctions or your drogue is undersized.