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Old Dec 04, 2013, 11:13 AM
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Ski / wheel combination for Hobbistar 60

I thought I'd try a hand at designing a ski / wheel combination for my Hobbistar 60. Thanks to the guys at my LHS and to the information at http://www.modelairplanenews.com/blo...eady-for-snow/. If I have time after my other winter projects for this plane I'll give it a shot.

Clicking the image will enlarge it.

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Old Dec 05, 2013, 10:34 AM
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I have shortened the length to 24" and after various feedback and a review of a lot of images have moved the wheel back 60% from the tip from its previous position at 40%. Version 2:

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Old Dec 06, 2013, 12:58 PM
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Very cool! Still one of my favorite, lazy, every day flying planes! Thanks for the info!
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Old Dec 06, 2013, 02:09 PM
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Very cool! Still one of my favorite, lazy, every day flying planes! Thanks for the info!
My pleasure!

Plans are up to version 3.1 - I've added runners to the bottom.

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Old Jan 13, 2014, 11:24 AM
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I finally got going on the skis yesterday. Off to a great start, I misread my plans, which stated a length of 2' 0". I cut them to 20". As it happens I had to lop another inch or so off the front for prop clearance - no biggie.

Here are the two blanks - 20" x 4".




Next step was to cut the wheel holes. To start, I squared up a stop block on the bench.




Both skis clamped against stop block.




Square outline of wheel hole.

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Old Jan 13, 2014, 11:32 AM
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I planned to use a hole saw to round off the inner corners, so I drilled 15/64" pilot holes to guide the hole saw's 1/4" pilot bit.




That done, I set the hole saw for 2-1/4" and chucked it in the drill.




First hole done... beforehand I had put a piece of scrap wood under the skis to keep from drilling into the bench top.




Both holes done. The alignment is off a hair on the second hole, but not enough to worry about.

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Old Jan 13, 2014, 11:37 AM
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Time for a little chiseling.






And some sanding.



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Old Jan 13, 2014, 11:50 AM
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Time for a test fit. Looking good so far.






I used a compass set to a 2" radius on the centre line 2" back from the leading edge to trace the tip profile.




Skis clamped together, I cut out the tips on the band saw.

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Old Jan 13, 2014, 11:59 AM
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Next I'll trace the outline onto the 1/4" ply I'm using for the spines and cut them out. Just getting started with that.

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Old Jan 13, 2014, 12:01 PM
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Very nice!
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Old Jan 13, 2014, 01:25 PM
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Thanks! As I progress I see I'm probably going to veer away from the design - we'll see how it all turns out.
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Old Jan 13, 2014, 08:06 PM
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Got the spines drawn - Before cutting I clamped the blanks and screwed them together. You may notice there are two where the drawings show four - I have decided to simplify and go with a single spline per ski. Well, one in front of the wheel and one behind - but both on the centre line. I am very much on the fly now and will make changes to the drawings later.




Here they are, fresh from the band saw. They still need to be cut to their final length - see the bottom photo.




Here are the aft spines.




Here's how they'll go on the skis.

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Old Jan 13, 2014, 08:08 PM
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Why did you decide on just one?
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Old Jan 13, 2014, 08:11 PM
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Marking the point on the ski where the curve begins.




I grabbed an offcut of the same 1/16" plywood made some passes with the mitre saw as a test.




The test piece was very bendy and clamped well. Not sure I like those huge kerfs, though.




I tried smaller kerfs with a fine back saw but the depth is very hard to control.

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Old Jan 13, 2014, 08:19 PM
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Why did you decide on just one?
I felt it would offer all the stiffness I needed while keeping down the weight and simplifying the build.
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