RC Plane Winter Skis

I was looking for a Ski to work on my friends T-28 RC Plane (https://www.horizonhobby.com/product/t-28-trojan-1.1m-bnf-basic-with-as3x-and-safe-select/EFL08250.html)

I started by printing this set of ski's: https://www.thingiverse.com/thing:4767767

I printed it with Siraya Tech Fast, which is more flexible/durable than most standard resins that i've come across. But in the cold minnesota winter, it became brittle and broke quite easily. I then printed it with a mix of Siraya Tech Fast and Tenacious, which is their flexible resin at 60:40 ratio and ultimately had the same thing. Last i tried printing 100% out of Tenacious, with the springs attached, the ski's were bowed upward, i could twist and bend the ski's in any direction easily and figured these would definitely not break, but they did! So I went down my own path of making something with a bit more support on the nose but retained his idea of using the leg clips and springs the ensure the ski's did not point downward.

So that brought me to MRCsledz46's ski design as a base/template, I needed to build some "towers" for the ski to mount. This RC Plane has 3mm wire used for its landing gear, with a 90 degree bend and then a screw on cap to keep the wheels in. I went through various designs before i settled on the current design. I then Put all the holes through the supports to help keep the Ski's as light as possible. I did print this with 1mm walls and 20% infill which you can notice while looking at the Smoky Black printed ski's. Theres ultimately not much weight to be saved by doing this, but my initial ski designs were weighing in at 2.36oz each and i wanted to bring that way down. Simply hollowing it out knocked off .2 ounces, and then adding the holes brought it down some more, and then i cropped the last 10mm off the back ends of the ski's and what i ultimately ended up at is 1.297oz!

Flight characteristics of the plane are the same as when wheels are attached, at least we cant feel a difference.

I have a wedge, each side being 15 degrees off vertical, These are the stops to prevent the ski's from moving too far up or down, so you have a 30 degree range of motion. So the 2 rear ski's are identical, that piece is just mirrored to the other side. The front ski has the same components, but i had to slide the tower forward a bit and i lowered it into the ski. For my plane, i needed to make the distance to the toe much shorter so that the ski's did not interfere with the prop, You could print a second one of the rear ski's if you have more nose clearance.

Results: On the very cold days, we eventually did crack the ski's, but the nose support on this ski made them last much much longer. On the days when its 20 and above, we could land pretty hard and the ski's wouldnt break. I've only printed this version of the ski's with Siraya Tech Fast resin (white and smoky black), i've not yet gone into mixing Tenacious with is like i did on the first ski i tried in an attempt to make it more durable as they've been working great as is.

The SpringClip file is the little clip that slides on the vertical portion of the landing gear to hold the top of the spring further up. In the images above, you can see that i had a couple of them placed on the struts as we tried different configurations. I found that i liked it when i scaled the z axis of this file to 800% to make it around 1.5" tall. You may have to mess with the X and Y scaling as well depending on the size of your landing gear struts to make them fit nice and snug.

**All my mentioning of ski's breaking, This is when we were landing on the Ice Rink portion of our lake, All of the ski's worked as expected when we landed in the actual snow

Please share a make if you do print these off, i'd love to see them

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