This is a downscale of Larry Brand's "Bottle Bat 3.0" design that can be found here on RocketReviews.com.
Due to the fact that plastic soft drink bottles have been resized and no longer fit inside standard rocket airframe tubing, a standard BTH-80 nose cone was substituted.
This one is called "Big Pink" for obvious reasons. It has 29mm motor tube and all up minus motor/case it weighs about 16 ounces or about 17 ounces if a 1/8" quick link is used to attach the chute. The fairing on the airframe conceals the knotted shock cord anchor. Standard milspec 550 para cord was used on this rocket. The tube fins are constructed with half doublers for strength to prevent "dreaded tube fin flutter". Five minute epoxy was used throughout the build.
Like most tube fin rockets, it's very wind resistant and climbs straight up. Due to the inherent high drag of tube fins, this one won't even reach 2000' on an H128. This is okay if you like to see the WHOLE flight including deployment. Keep this low altitude performance in mind when selecting recovery delays.
Minimum motor choice should be F52.
| Flight Date: | 2011-03-12 |
| Rocket Name: | Bottle Bat 2.6 (Tube Fin) |
| Flyer's Name: | K Sonesen |
| Motors: | G64 |
| Expected Altitude: | 1,200 Feet |
| Wind Speed: | 5.00 mph |
| Launch Site: | SARG - Amoruso Field |
| Actual Altitude: | 1,448 Feet |
Early in the day wind gusts reached 16 mph. By midday the winds had dropped to 7-10mph. Thinking I could save myself a long recovery hike, I decided to use an 18" chute instead of the normal 24".
The boost was very straight (tube fin, right?) and VERY high. My reduced chute size strategy paid off and my recovery walk was less than 100 yards. My new Altimeter One said 1448' feet. Oops. I'd been using a Cd of 1.5 in my sims but based on that altitude, I should have used a Cd of 0.90. The downside of the small chute was that two of the tube fins separated from the airframe on impact. It just hit right. The epoxy didn't fail but a layer of the tubing pulled away from the airframe. The damage is repairable.
I love this bird!
| Stage | Motor(s) |
|---|---|
| 1 | Aerotech G64 |
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