Sport Rocketry

perimeter of the ring. is gives it the sprocket-like appearance and allows for the necessary ventilation. ey can be used for BT-60 rockets with 18mm and 24mm motors, and for BT-55 rockets with 18mm motors (Figure 5). if air is moving freely or not through a baf- fle. To build the flute-and-sprocket baffle, first make the flute tube. Get a 2.25" length of tubing that matches the motor tube you are using. Use a standard (6mm) single hole punch (I got mine at a dollar store) to cleanly cut holes in the tube (Figure 6). 18mm tubes get 9 holes, and 24mm tubes get 16 holes. Keep the holes at least 3/8 inch from one end. Glue the engine block and bulkhead flush with this end as shown. Glue a centering ring at the opposite end. Figure 7 shows the parts of the baffle: e bulkhead and engine block get glued in to the le side of the tube in this image; the right side of the baffle with the solid center- ing ring faces the motor. SPORT ROCKETRY MAY/JUNE 2022 23 Figure 2. A flute-and-strainer baffle that survived a cato. Figure 3. e almost pristine topside of the baffle that survived the cato shows that the cato damage was well contained. Figure 4. A cato in this Atlas V-541 model destroyed the baffle, but the baffle protected the recovery system and Chute Release. Figure 5. ree flute-and-sprocket baffles. For the sake of brevity, I've skipped the math used for calculating adequate venti- lation (for more information see Apogee's Peak of Flight Newsletter #463). But rest assured, this baffle meets or exceeds what's necessary. And while I don't have any fan- cy instruments to measure pressurization, I do have the next best thing: the human mouth. A few "puff " tests will let you know

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