Estes Monarch Build, #7214, Part 8, Downsizing The Optima To A BT-55

Downsizing is often a compromise.

I don't have a Optima shaped nose cone. For now, I'll be using the nose cone from the Monarch kit.

The Estes online specs say the Pro Series II Optima has a 2.5" (outside diameter) body tube.

This might be a BT-80 tube with the diameter rounded down to 2.5". The BT-80 diameter is actually 2.6".

This downscale is built around a BT-55 at 1.325" diameter, very close to a half size downscale.

For my build, I used the 2.5" tube measurement, downscaled to the BT-55 size of 1.325".

Multiply all dimensions by .53 to get your downsize dimensions.

The full size Optima is 48.5" tall.

Multiply the 48.5" X .53 = 25.70" downsize height.

The nose cone length is 5" exposed. 

That leaves 20.70" of body tube. The fins are even with the bottom of the lower tube.

Using just the original two tubes from the Monarch kit, the downscaled Optima looked short.

The lower tube (with the engine mount) from the Monarch kit is 9" long.

I cut a scrap BT-55 tube to the remaining 11.70" for the upper tube.