Dave Oplinger posted a question on the Model Rocketry Fanatics Facebook page:
"So, what was the deal with these cold propellant engines that Estes had at one time? Did anyone have one? How did they work? Were they too troublesome or expensive? Maybe someone still offers something similar?"
These two were from the Cold Power Convertible line. A smaller Vashon style aluminum engine that slid into a BT-50 body tube. A smaller tube attached to a spring would "eject' the parachute. The performance of the smaller engines in these could be the equivalent of a B6-4 on a warmer day. You couldn't launch these if it was too cold, the freon was a self refrigerant. After you got bored with the lackluster performance of the smaller cold power, Estes sold standard 18mm engine mounts for BP engines. These Convertibles did not use the string and pin "launch". These had a cable, nozzle clamp and a hand held controller. Press the thumb button and the clamp released the plug. Vashon was bought out by Damon and absorbed into the Estes catalog.
I did buy and fly the Shark a few times. To see the instructions, CLICK HERE
Construction of the air frame, fins and nose cone were normal. The smaller aluminum "tank" engine slid in, friction fitted from the rear.
In the center is the "Remote Release Button". The thumb plunger was pressed in, the cable pulled and the "fueling adapter" plug was released from the nozzle.
One disadvantage to this series was that spring! The spring was always extended looking like a comical broken toy on your model shelf. I called it my "Jack in the Box" rocket.The upper piston tube and nose section were always hanging out of the model until it was pressurized right before flight.
Here's the older, original Vashon firing assembly.
The nozzle plug was inserted into the nozzle. The safety pin was pushed through two small holes in the nozzle sides and held the plug in place. The engine tank was filled.
When ready you would pull the pin and the plug would be pushed out the back.
Vashon also made an electric launched system. A wire held the plug in the nozzle.
Electric current would heat the wire breaking it. The plug would blow out and the model would launch.