Snow Skimmers

 

A couple great projects for those with snow over the winter: making a fun RC "car" using plane parts. See below for more details-

 Flying Fish:

 Pod Racer:

Flying Fish Build Details:

The Details: Flying Fish is 28" long and 15" wide.  Each of the pontoon skis are 3" wide, up to 4" tall and tapering down to 1" tall in the back.  The skis are made from 5mm MPF foam board, hot glue, wooden dowels and increasing amounts of tape.  After numerous hot glue and duct tape repairs the skimmer weighs 600g (w/o battery). Electronics include a 3c cell 2200mAh lipo (mounted fully forward in the bay), a SunnySki x2212 motor with a 7x3.8" prop. I initially had the motor angled up 6 degrees, but found it works best when shimmed to neutral.
 

Ski Surface: The surface of each ski should be slick and uniform side to side.  First I used packing tape. This initially worked well but tended to lose adhesion after exposure to snow, and tore easily from protruding sticks, etc.  Iron-on laminate "new stuff" worked better, but eventually also tore and lost adhesion.  So far, white duct tape has worked best.  If you noticed in the video that I am only turning left (like NASCAR), that was due to the left ski surface being torn up a bit, creating extra drag and making a right turns almost impossible. It's important to have each ski surface the same!

Further Thoughts: While it works well overall, the Flying Fish's weak spots are turning (in soft snow) and durability.  I tried increasing the length of the rudders; while this certainly helped, it still turns wide in softer snow.  The overall width seems to be about right in balancing stability and tracking.  The Flying Fish occasionally flips over during turning, especially when there is a cross wind.  Skimming over rough/icy snow and taking jumps resulted in frequent hot glue and duct tape repairs to the deck-pontoon and rudders-elevator joints.  On a future build, I would love to try adding some type of ski suspension, durable joints, and a fiberglass ski surface. I might also experimenting with rounding the edges of the skis to facilitate turning.  This model has dual ailerons, elevator and dual rudders.  The ailerons help to stabilize after jumping off at an angle and during turning, but are not required.  The dihedral winglets provide lift and help to stabilize the skimmer in the air; I am curious about what happens when these are removed.  The elevator is needed to initiate leaps and to control pitch coming off jumps, but is optional on totally flat snow.  The rudder is required, however, and could be considerably larger. 

 

 Pod Racer Build Details

The Build: I used layers of 1" thick insulation foam, covered in 6oz fiberglass and 8mm carbon fiber spars.  Electronics include dual x2206 1620kv motors, 5x5x3.8 props, and a 3c 2200mAh battery. I originally planned to steer using differential thrust from the motors, but that was not enough - I definitely needed a large rudder as well.  The total width is 19" (based on cutting a 1m shaft in half).  The original central hull length of 17" made it way too squirrelly, while a longer length of 26" (or 31" to back of rudder) worked much better.  Like the Flying Fish, having the length almost double the width seems to work best overall.

For best tracking, I placed the battery was in the back section and angled the motors upward ~10-15°.  (This worked well with my setup, but may result in too much lift using higher kv or larger props.) I had added in motor pitch control to dial in settings for different snow conditions, but found that the same motor angle worked best in both soft and hard pack snow.

The wide spacing of the pontoons made for great stability (it never tipped over) but the initial design would not track straight. After adding 9'' to the length, stability and tracking was excellent on flat terrain (and even balanced it out allowing it to take off from low angle jumps).  The fiberglass hull coverings proved their durability and have not needed any repair.

 

 

If there is interest, I can add stl files and add't build info.  

Plans: TBD

STL files: TBD