RC Jet Drives

A big part of the amphibious RC vehicle I made was developing a mechanism for water navigation. My team and I pursued a "Jet Drive" system, similar to that in a Jet Ski, which I designed. CAD-ing and fabricating the jet drive was an iterative process, in which I made use of quick prototyping methods such as 3D printing to quickly see what needed improvement

The jet drive was printed as a single part for integrity. The motor sits on the end and is coupled to the impeller shaft. A water tight bearing sits in the middle in order to constrain the motion and reduce rotational friction. Additionally, grease was added to keep the pontoons watertight (water pushes the grease against the press fit bearing to create a seal). To finish the component, solvent bonding was used for added strength to "weld" the printed layers together

The drives worked very well for our vehicle, and we clocked in as the fastest boat during the competition. In fact they ended up being so powerful they accidentally flipped over a competing boat when we went head to head. The design wasn't without flaws however, in retrospect there were two things that we forgot to consider: the impeller shaft would hit its resonant frequency at high speeds, causing it to vibrate wildly within the drive - the cross seen in the CAD was added last minute to help with this; at high speeds cavitation would occasionally occur, causing brief slow downs in the boat movement. Given more time these issues would have been the next thing I tackled

Though I did not take any videos once it was integrated into the RC vehicle, the performance can be seen in the video below: