Ye Olde Rocket Forum - View Single Post - Agitating for Series 17 tubing

Quote:

Originally Posted by MarkB.

... Frankly, there's nothing that would indicate that a manufacturer would be "stuck" with this size tubing any more than Estes was ever "stuck" with odd-ball sized BT-52 tubing or BT-65 or some of their other off-size tubing they have made over the years. The answer is make something out of it...

I would tend to agree. There really seems to be little in the 1.7x OD range, and a few scale kits as you suggest would open that possibility up.

I recognize that in suggesting an ST-17 you'd be in keeping with the Centuri approach of 1.700" ID/1.740" OD, but that would technically render the Black Brant V model slightly larger than 1/10th size (the motor case had an OD of 17.26"), but hardly an issue for a sport scale model. I seem to recall that Taras Tataryn produced just such an airframe some years ago for his line of ARG 1/10th size Black Brant kits, so it has been done before. Producing the airframe for kits also makes life a lot easier for scratch builders, as you also point out.

The combination of airframe and tail can diameters is somewhat problematic for the BBVC, as they are so close - 17.26" for the motor casing, 16.20" for the tail can. It's hard finding a set of manufactured tubes that fit this ratio exactly. A few years ago I built a Black Brant VIII, and my approach was to use BT-70 for the BBVC airframe, and a piece of ST-20 for the tail can. The scale factor was set to the airframe, which returned a SF value of 1:7.79. That meant the tail can would need a wrap of 0.020" Styrene to build it out to the correct scale diameter. Sometimes there just aren't going to be the "right" tubes for a precise scale build, and so one adjusts, depending on the goal of the project.

I'd certainly welcome a 1.7x OD tube, and if it introduced some mainstream scale kits, so much the better.