Howdy. I would greatly appreciate some ideas to create a device to launch a 40 pound weight down a 150' flat sheet of ice. I want to have some limited ability to increase/decrease the power. I want this to be the simplest construction possible -- maybe using springs that can be added or removed.

It must operate at cold temperatures (25 to 30 F). I thought about using a large counterweight on a ramp, but that might be too hard to move.

Many thanks for any suggestions! Inexpensive options would be preferred.