Greetings to all, You have a sheet of level glass 10 ft long. At one end is a small ramp of 1 inch tall. On top of ramp is sled with two sets of roller blade trucks and wheels that have very low friction on glass. On top of sled is x device. Sled is released and it rolls about 3 feet and stops. you repeat this test 3 times with the same result every-time. Now you turn on device with thrust point strait out in front. You release the sled and it rolls down the ramp but this time it keeps going far past the 3 foot mark and almost goes off the table traveling in a strait line. The test is repeated 3 times with the same result each time. With the device still on it is placed at top of ramp, however this time the thrust in pointed up. Sled is released and rolls down to the 3 foot mark and stops. Test is repeated 3 times with same results each time. What can we conclude from this test. Device and sled together weight 17 lbs. Dimensions of sled: 12" x 9" Thank you, Metalspider