Oeuf and Ool

As I mentioned in my previous post, I have started designing and building my rockets for this year's Geezer TARC. The first of these, Oeuf (french for "egg"), is an Alpha-like model based on the Centuri ST-18 body tube (minimum diameter for a regulation TARC egg). It's powered by up to 4 18mm motors, though OpenRocket is saying two D motors will be sufficient, provided I don't exceed the design weight. If I do,  I can always put A, B, or C motors in the other two tubes - Oeuf ain't nothing if not flexible. Right now, she's waiting for her first primer coat to dry.

OpenRocket visualization of Oeuf during dual motor thrust (Click to enlarge).

I have just started work on the second design, called "Ool" after the name for food in one of my favorite movies, "Caveman." Ool is a 3 finned BT-55 to BT-70 rocket, propelled by a single 24 mm motor. She's designed light, a tad over 200 grams without motor, and will sport the Apogee conformal rail guides - a first for one of my rockets. OpenRocket is projecting that a single E12 will provide more than enough juice to make 800 feet; thrust-to-weight is an acceptable 4.7:1, close enough to the magic 5:1. Motor mount is assembled, body tube spirals have been filled, and the balsa fins have been cut and skinned. I originally had smaller fins, but they struck me as too small, even though the sim was telling me the static stability margin was 1.5 without the egg and altimeter. So I upscaled them by 125%, which appeased my rocket instincts and improved the stability margin up to 2.1 without the payloads.

Visualization of Ool under E12 power (Click to enlarge).

Yeah, I know Open Rocket said it was stable, but I have seen too many TARC rockets that were rated as stable by the sim go very squirrelly after leaving the rail. Not going to happen with one of my birds.

I hope to have the fins on Ool tomorrow and to apply primer sometime during the upcoming week. Depends on if we can get a break in the recent bout of stormy weather.