It’s hard to get excited about a cardboard tube. But, when that tube opens up new possibilities for model rocketry, it is newsworthy.
Here are reasons why you should be excited about the new BT20-H body tube.
The BT-20H is thicker and more durable than a standard BT-20. The inside diameter of the BT-20H is the same as the inside diameter of a standard BT-20 body tube, 0.710 inches (just a hair over 18mm). But, the wall of the BT-20H is about 60% thicker – 0.021 inches thick versus 0.013 inches for a plain BT-20. This extra thickness makes the tube much stronger.
The BT-20H is perfect for 18mm motor mounts. A rocket’s motor mount can take some abuse as you insert and remove motors and during flight from the thrust of the motor and the ejection charge, so the extra strength of the BT-20H makes it a good choice in motor mounts for standard size motors. The inside diameter of the BT-20H is the same as the BT-20, so you can use a standard 18mm thrust ring. Standard engine hooks also work and there’s less chance of the tube tearing in the slot you make for the top of the hook. A more robust engine mount made with a BT-20H is perfect for use with the powerful 18mm composite D motors from Quest.
You can use standard centering rings. Even though the outside diameter of the BT-20H is larger than the BT-20’s, you can still use standard BT-20 centering rings. The inside of a standard centering ring can easily be sanded (or peeled) to fit the slightly larger diameter of the BT-20H.
You can use standard nose cones. Standard BT-20 nose cones fit the BT-20H tubes. Because the BT-20H is slightly larger in diameter than a BT-20, there might be a small lip around the end of the body tube.
The thicker BT-20H provides better heat resistance than thinner BT-20 tubes. Being more resistant to the effects of the motor’s ejection charge makes the BT-20H a better choice for motor tubes and, especially, for stuffer tubes.
BT-20Hs are easier to work with. Being thicker and more durable makes the BT-20Hs easier to cut and less likely to be crushed during construction of a rocket.
The BT-20Hs open up new possibilities. A stronger body tube allows for more complex designs such as rockets with strap-on boosters or extra-long “super-rocs.”