I just bought a Wildman Demon 5. It's a HED build (a first for me) with a boat tail that pretty much contains the entire fin and motor mount assembly, leaving the vast majority of the 48" airframe empty. The only things that have to fit are the drogue and drogue harness, which aren't going to need a ton of airframe length in a 5" diameter rocket. I have two objectives I'd like to accomplish as I build this (besides the usual):
1. Keep the bottom of the drogue harness accessible and replaceable.
2. Reduce the quantity of BP required (Vern K's rough estimate is 8g if I leave the whole airframe empty).
#2 was not initially on my mind, so my solution to #1 was to build the tail cone/fin can as its own assembly, attaching it to the main airframe with several removable screws through the airframe and the tail cone coupler. This would allow me to remove the airframe to check/repair/replace the recovery harness mounting point. That's still on the table, but when I thought of the volume of that empty airframe, I thought why not put a bulkhead 18" (or so) down from the nose end? This is dual deploy and there's no way I could fit enough BP in the motor well to be a useful backup, so blocking the motor section off from the separable parts doesn't seem like an issue. The airframe plus the tail cone is so long it's not going to prevent me from using a Pro75 6XL casing (which is probably not ever in my future anyway), so that's also not an issue. I could probably reach down 18" into a 5" airframe, but why not make this mount removable too?
My thought is to sandwich a bulk plate (with a coupler bulk plate on either side for strength and centering) between two short pieces of coupler, and mount a u-bolt to that. I would attach it to the airframe with several (3? 4?) screws (maybe 1/4", I have those lying around) into pem nuts mounted in the coupler. Here's the section from my OR sim (not including the hardware).
Does this make sense? Will it work to accomplish my objectives? Is it overkill? Do you have a better way to accomplish the two objectives above? I know I'm not the first person to try to accomplish them, so I'd love to learn from other people's experience.
Thanks!
1. Keep the bottom of the drogue harness accessible and replaceable.
2. Reduce the quantity of BP required (Vern K's rough estimate is 8g if I leave the whole airframe empty).
#2 was not initially on my mind, so my solution to #1 was to build the tail cone/fin can as its own assembly, attaching it to the main airframe with several removable screws through the airframe and the tail cone coupler. This would allow me to remove the airframe to check/repair/replace the recovery harness mounting point. That's still on the table, but when I thought of the volume of that empty airframe, I thought why not put a bulkhead 18" (or so) down from the nose end? This is dual deploy and there's no way I could fit enough BP in the motor well to be a useful backup, so blocking the motor section off from the separable parts doesn't seem like an issue. The airframe plus the tail cone is so long it's not going to prevent me from using a Pro75 6XL casing (which is probably not ever in my future anyway), so that's also not an issue. I could probably reach down 18" into a 5" airframe, but why not make this mount removable too?
My thought is to sandwich a bulk plate (with a coupler bulk plate on either side for strength and centering) between two short pieces of coupler, and mount a u-bolt to that. I would attach it to the airframe with several (3? 4?) screws (maybe 1/4", I have those lying around) into pem nuts mounted in the coupler. Here's the section from my OR sim (not including the hardware).
Does this make sense? Will it work to accomplish my objectives? Is it overkill? Do you have a better way to accomplish the two objectives above? I know I'm not the first person to try to accomplish them, so I'd love to learn from other people's experience.
Thanks!