Thursday, May 28, 2009

Machnum Force almost complete

I made some more progress on it today. This morning, I put the second or third fillets on the third fin, so all three are attached perfecty.

I found a shock cord - 2 feet of 1/4" elastic. Hopefully it'll survive the ejection charge.

This afternoon, I drew 'MACHNUM FORCE' in block letters down the side of the rocket. then colored 'MACH' in blue and 'NUM FORCE' in black. The lettering smudged a bit afterwards, but it still looks pretty snazzy.

Finally, I've applied 3 layers of wood glue to the entire body tube as a smooth finish. It's a bit bumpy and imperfect, but I think sanding it with early-smooth sandpaper will clean it up a lot. With the entire rocket - nose cone, body tube, and fins - covered by 3 layers of wood glue, it'll be practically indestructable.

After the sanding, the only thing left to do is to attach the shock cord with an Estes-style mount, then wood glue over it for protection from the ejection charge.

Even with lots of protection for the shock cord, streamer, and nose cone (yet more wood glue on the underside of the shoulder). the recovery system will still take a beating from the G-size ejection charge exploding in just 6" free space of 29mm tubing. If I get a loadable motor - G77, G78, or G79 - then I might only put in half or a third of the ejection charge. Since it's still enough to deploy the system and it's not modifying the propellant, I think it's perfectly legal under the safety code.

This is my last post till Sunday except for the automated one in a few minutes. See you then.

1 comment:

Sascha Grant said...

Reducing the ejection charge should be fine - and is quite common. There's calculators online that will help you work out the correct amount. A good digital scale ( .1 or .01 of a gram ) can come in handy for this type of thing. Harbor Freight have digital scales for $9.99