I know, I know. Another Optima. What can I say, I like the design
I wound up with 2 vinyl logos that were perfect size for BT60. Rather than let them go to waste, I HAD to build rockets for them. The best way I figured to get all the parts I needed was to raid the parts box, and grab a Mean Machine kit.
The Optima is 47.5 inches tall, and 2.6 inches wide. Since BT60 is 1.64", I went with a height of about 30". Two optimas therefore only required a total of 3 tubes. I used the 4th to make a "Stumpy Machine"
I made kevlar harnesses and wrapped them around the top of the MMTs, then glued them into place. The kevlar is about an inch shorter than the body, and 48" elastic cords are tied to the ends.
Fins were cut from 1/8 plywood, stacked together and sanded.
This next photo shows the rocket in the fin jig, and the downscale fin conversions. I have a set of Semroc reproduction fins in full size. I measured them, and then converted the fractions to decimal. Then I calculated the downscale. Once I had those numbers I converted back to fractions using this chart: https://www.seoconsultants.com/charts/inches-decimal/ It's not exact, but it's close enough for government work. There's probably an easier way to do this, but it worked for me. Once I had the numbers, I used the full size set of fins to trace the angles.
And all the fins drying up:
I wound up with 2 vinyl logos that were perfect size for BT60. Rather than let them go to waste, I HAD to build rockets for them. The best way I figured to get all the parts I needed was to raid the parts box, and grab a Mean Machine kit.
The Optima is 47.5 inches tall, and 2.6 inches wide. Since BT60 is 1.64", I went with a height of about 30". Two optimas therefore only required a total of 3 tubes. I used the 4th to make a "Stumpy Machine"
I made kevlar harnesses and wrapped them around the top of the MMTs, then glued them into place. The kevlar is about an inch shorter than the body, and 48" elastic cords are tied to the ends.
Fins were cut from 1/8 plywood, stacked together and sanded.
This next photo shows the rocket in the fin jig, and the downscale fin conversions. I have a set of Semroc reproduction fins in full size. I measured them, and then converted the fractions to decimal. Then I calculated the downscale. Once I had those numbers I converted back to fractions using this chart: https://www.seoconsultants.com/charts/inches-decimal/ It's not exact, but it's close enough for government work. There's probably an easier way to do this, but it worked for me. Once I had the numbers, I used the full size set of fins to trace the angles.
And all the fins drying up: