Hotrod's Buffalo DD started

Had some time last night and got this thing started. Fins are not precut so I stacked them up and used the scroll saw to cut them out and then sanded the edges. Tube isn't slotted either so I laid it out and cut slots with a straightedge and an exacto knife. Seemed to come out pretty good (I don't have a fin alignment jig) but we'll see when i put her in the air.

This is my first av bay and it's tight. I'm going to look into using a lipo instead of a 9v to save some weight. Also going to try the x-mas light igniter idea.

I'm planning on putting this together box stock, but I've only built one other mpr so any comments or ideas are appreciated.

Pretty nice av bay. I found the kit at: https://www.hotrodrocketshop.com/Buffalo.html

Cool, I got one of these kits for Christmas too. Haven't had a chance to start building yet - hopefully I can clear off my bench and get started soon.

Mike

It's all new to me--hope I get it right the first time!

Quick question. As I understand, the drogue will eject from between the lower body and av bay, and the main at the nose. Do I simply keep the nose tighter than the bay to keep it from separating unexpectedly when the first charge goes off? Should 10 ln/ft of shock cord be sufficient at each end?

Ten feet on a rocket this size is going to be plenty in my opinion. For keeping the nosecone on, you can either friction fit it and make it tight or use shear pins that break when the charge goes off. They go through the tube into the nosecone and hold it in place.

How important are fillets on the fins of a rocket this size. I'm using titebond for 99% of this, and have run glue fillets on the outside of the body tube, but I see many people taping and epoxying large fillets. I know it looks cool, but does it affect stability on something this size, or is it for strength?

TRossi said:

How important are fillets on the fins of a rocket this size. I'm using titebond for 99% of this, and have run glue fillets on the outside of the body tube, but I see many people taping and epoxying large fillets. I know it looks cool, but does it affect stability on something this size, or is it for strength?

Click to expand...

Fillets on large rockets are for strength and aerodynamic effects. The smooth the connection between the tube and fin, add more surface area for the fin to contact the tube, and provide support to the joint. I put fillets on rockets this size and all the way down to 29mm minimum diameter rockets. The do not need to be large for something this size. You can just use the end of an X-acto knife, a popsicle stick, or a sharpie cap. I have used all three with success. There is no effect on stability except for a bit of weight in the tail end, but it should not be a problem provided that the fillets are not gigantic.