Скачать или смотреть Technical LEGO: X-ray, a rubber band boat, tub trial

X-ray is my 1st attempt at a rubber band-powered LEGO boat. She won't be setting any speed records, but she makes a great tub or wading pool toy under adult supervision (to insure that the structures resisting the rubber band's tension remain firmly seated.)

Though too small to carry LEGO electric motors, the very lightweight, low-resistance 28x8x3.6 LU Fishing Boat hull (92710c01pb01) turns out to be ideal for this application.

X-ray displaces 100 g. The modified prop is a left-handed 44 mm 2-blade LEGO® "twisted propeller" (4745) with blades hand-sanded into thrust-enhancing hydrodynamic profiles. The same prop with unmodified blades is ~30% slower.

Optimal gearing depends on the prop. The prop with modified blades works best at a 1:1 final drive ratio, whereas the unmodified prop does best at a 1:2.8 overdrive ratio.

One would expect single-screw boat with a left-handed prop to pull a little to starboard due to prop walk. When X-ray's released straight down the tub and spun around manually on reaching the ends, the rubber band is good for 4-6 tub lengths of travel on a single wind.

Photos and write-up at http://www.moc-pages.com/moc.php/418433.