Main above or below A/V bay

I wonder if it makes a difference putting the drogue below the A/V bay and the main above of the other way around.

Ari.

I do not think so. I have seen it done both ways and I have done it both ways. I would recommend you pick a way and do it that way everytime so that it lowers you chance of error. I put my drogue in the middle now because it is the way everyone else does it and uniformity reduces error.

The only benefit I can think of to use the top compartment for the main is not you have two large peices falling to slow it down more if you decide to go drogueless. I have no proof but that is the only reason I can think of.

I am eager to see other responses.

Another advantage to keeping the drogue to the motor side is motor backup at (or just past) apogee. Not an option if your main is on that side.

In a standard dual-break setup, physics says put your drogue in the fin can and your main in the payload just below the nose cone. If the main is in the lower section, nearly the entire weight of the rocket (fins + motor case + rings + airframe) are pulling on the junction where the main deploys during the ride down; if the main is in the upper section, it's just the nose cone staying put.

Granted, it's possible with some massive shear pins (and ensuing massive deployment charges). But for the sake of simplicity and reliability, I have almost always seen it the traditional way.

Thanks guys.

Ari.

If something goes wrong with deployment and the drogue gets shredded and the line breaks, you want the resulting sections to not be stable. It is possible with some rockets that if the nosecone is removed, the rocket is still stable. Such a rocket could come in ballistic. Breaking it in the middle makes it unlikely the fin section will still be stable.

Gerald

If you put the drogue in the lower section close to the av-bay, it will tend to keep the upper section above the lower prior to main deployment. This can help prevent the main from fouling on the airframe when it deploys.

I think this video posted by Qquake shows the whole deploment sequence really well.[video=youtube;_nZKzvwpcQ8]https://www.youtube.com/watch?v=_nZKzvwpcQ8[/video]