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Thread: Ski rigging techniques

  1. #1
    spinner2's Avatar
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    Ski rigging techniques

    After recently rigging my Carbon Concepts board skis I Thought I'd share my technique and where I sourced materials.

    Both my plane and the skis are not certified so I'm not bound by an STC or Field Approval. I made reference to both 43.13 and Dodge's online ski rigging tips. Both are very helpful.

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    The skis were received from Randy with pedestals but no rigging or attach points on the skis.

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    I purchased the toe and tail attach fittings from Stoddards along with stainless steel axle washers. The fittings that attach on the gear bolts and the bungees came from Reeve's.

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    I found some stainless steel clevis' with a high load rating from industrial supplier MSC that came with a 5/16" diameter pin.

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    The threaded half of the clevis is threaded 5/16-24 so I replaced the pin with and AN5 bolt and as a keeper threaded on an AN nut. The plastic donut is UHMW that I machined a 1/2" radius into and drilled 5/16" for the bolt to pass through.

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    On the gear attach point I used a Ronstan brand 6mm stainless steel, high load rated chain link. A hole was drilled though the hex section to accept a cotter key.

    The second cable on the right is the check cable.

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    Setting the angles for ski movement was made easy using a chain hoist, comealong, and a smart level.

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    The first step is to set the length of the check cables. I went with a maximum down angle, should the bungee fail, of nine degrees. 43.13 allows for considerably more than this, but less seems better as long as there is enough slack to allow full ski movement over uneven ground.

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    The next step is setting the length of the rear cable. With the skis flat on the hangar floor I raised the rear of the plane with a comealong. I found that one click of the ratchet was equal to one tenth of a degree on the smart level with the placement I used.

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    I went with 1.5 degrees nose up ski attitude in flight. This meant raising the tail 1.5 degrees above level and the setting the rear cable to this length.

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    Lastly the the bungees are attached and the length of the crust cutter cable is determined by the amount of down force required to stretch the bungees. 43.13 has a poundage guide based on ski displacement. This step is a little subjective and not real easy to measure. But the end goal is to have enough tension on the skis through the bungees that there is no in-flight flutter of the skis.

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    The rigged skis weighed 33.2 pounds each. 1/8" diameter control cable was used per 43.13 for skis and a plane this size. After finding the center of balance for the rigged skis I made a new W&B. This is easy to do when existing component weights and arms are already in an Excel file.

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    A pair of Dolly's were fabricated too.

    I'm sure there are other ways to accomplish the same results but this is how I rigged these skis.
    Last edited by spinner2; 11-20-2016 at 01:41 PM.
    "Fast is fine, but accuracy is everything." Wyatt Earp
    Thanks tedwaltman1 thanked for this post

  2. #2
    BC12D-4-85's Avatar
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    Keep an eye on your rear ski thimbles. If you notice stretching or flattening of the shape and often taxi over big drifts add some length as more nose up/longer rear cable may be desired.

    GAP

  3. #3
    cubdriver2's Avatar
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    Also after your bungees are setting in tension for awhile ( tail down ) that your bungees won't return to where you originally had them, they stretch out a little

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"
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  4. #4
    BC12D-4-85's Avatar
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    There was a time when it got cold that bungees were replaced with Atlee Dodge springs. On the ground the bungees wouldn't react to changes in ski position quickly enough and tended to stretch in flight under wind load and flop around. That's at about -30F or colder in my experience. Maybe there's better shock cord material available now or some skis can't use springs for some reason. I like springs as they never wear out much due to sun and weathering.

    GAP

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    Quote Originally Posted by BC12D-4-85 View Post
    There was a time when it got cold that bungees were replaced with Atlee Dodge springs. On the ground the bungees wouldn't react to changes in ski position quickly enough and tended to stretch in flight under wind load and flop around. That's at about -30F or colder in my experience. Maybe there's better shock cord material available now or some skis can't use springs for some reason. I like springs as they never wear out much due to sun and weathering.

    GAP
    No experience with skis, but I've watched regular bungee cords slack to full extension in roughly-20/-30 weather. When brought back inside to warm up, we watched them shrink back to their normal unstretched size as they got back to room temperature. If I was flying anything that depended on bungees in a really cold environment, I'd look into springs too.

  6. #6

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    Put some silicone tape around that wire at the top of the bungie it will start to chafe quickly due to the wind.
    DENNY

  7. #7
    spinner2's Avatar
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    Quote Originally Posted by DENNY View Post
    Put some silicone tape around that wire at the top of the bungie it will start to chafe quickly due to the wind.
    DENNY
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    Good suggestion. I put some spiral wire wrap around both ends on both sides.
    "Fast is fine, but accuracy is everything." Wyatt Earp

  8. #8
    cubdriver2's Avatar
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    Quote Originally Posted by spinner2 View Post
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    Good suggestion. I put some spiral wire wrap around both ends on both sides.
    And it's safe to use the $2 3/16" chain repair links sold at Ace, I hooked one between my truck and tractor and couldn't break it.

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"
    Thanks A BELLAND thanked for this post

  9. #9
    cubdriver2's Avatar
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    We had a foot or more of snow last Sunday but then the wind blew for a few days. Got to play a little today

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    Step comes in handy

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    Was having fun till freezing rain

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    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  10. #10
    RaisedByWolves's Avatar
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    Joe didn't come play?


    Sent from my iPhone using Tapatalk

  11. #11
    skukum12's Avatar
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    Glenn, telling us Alaska boys you have been ski flying is enough to get this thread sent to RnR
    "Always looking up"

  12. #12
    cubdriver2's Avatar
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    Quote Originally Posted by skukum12 View Post
    Glenn, telling us Alaska boys you have been ski flying is enough to get this thread sent to RnR
    Don't you have any snow?

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  13. #13
    skukum12's Avatar
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    Nothing here in southcentral (Wasilla/Anchorage/Kenai). Airstrips dry as a bone. Only chance for skis is being based on lake ice, but then there is nowhere yet to land other than some other lake. Not sure how northeren Ak is doing.
    "Always looking up"

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    We need the ice before we need snow.

  15. #15

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    Quote Originally Posted by spinner2 View Post
    After recently rigging my Carbon Concepts board skis...
    Nice work. I hope to see these skis out and about this winter. Up here I mean.
    Likes WanaBNACub liked this post

  16. #16

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    Quote Originally Posted by skukum12 View Post
    Nothing here in southcentral...
    Ya, nothing but hoar frost on top of ten inches of ice here. We have half the equation. Now we need ten inches of snow.
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  17. #17
    Ruffair's Avatar
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    Good ice, no sno on Dune Lake, (sw of fai )

    btw, this photo my get submitted for next calendar thing.... Cause I didn't take it..!
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    Last edited by Ruffair; 11-27-2016 at 01:53 PM.
    "...We're fast enough to get there, But slow enough to see..."
    Fron the song "Barometer Soup". By Jimmy Buffett

  18. #18
    nanook's Avatar
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    Quote Originally Posted by BC12D-4-85 View Post
    Keep an eye on your rear ski thimbles. If you notice stretching or flattening of the shape and often taxi over big drifts add some length as more nose up/longer rear cable may be desired.

    GAP
    that is why 1/8" cable is too small for the check cable... Lose the bungees for springs...

  19. #19
    spinner2's Avatar
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    I've got about 25 hours and perhaps as many as 300 landings on these skis now and I am really pleased with the skis and the rigging. Without snowshoes on, the snow in this picture would let me sink past my knees. These skis also turn very tight with some forward stick both to the left and right.

    I made a takeoff a few days ago into a 20 mph headwind and a DA of about -1500' and I'm sure the skis didn't slide more than about a ski length before I was in the air.
    "Fast is fine, but accuracy is everything." Wyatt Earp
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  20. #20

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    "I've got about 25 hours and perhaps as many as 300 landings on these skis"

    Wow. A landing every five minutes? Wow.

  21. #21
    spinner2's Avatar
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    Quote Originally Posted by Randyk View Post
    "I've got about 25 hours and perhaps as many as 300 landings on these skis"

    Wow. A landing every five minutes? Wow.
    I didn't do the math but I love to make multiple landings. I've got a couple of places, like on the reservoir yesterday, where I'd take off and get about 25' in the air and then make another landing. A minute or two later another one. And out there you can do that for 10 miles each direction. It doesn't take long to make a bunch of landings. Yesterday was such a great day I was out there for a long time....
    "Fast is fine, but accuracy is everything." Wyatt Earp

  22. #22
    cubdriver2's Avatar
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    Quote Originally Posted by spinner2 View Post
    I didn't do the math but I love to make multiple landings. I've got a couple of places, like on the reservoir yesterday, where I'd take off and get about 25' in the air and then make another landing. A minute or two later another one. And out there you can do that for 10 miles each direction. It doesn't take long to make a bunch of landings. Yesterday was such a great day I was out there for a long time....
    Until you get powder like that to play in nobody will understand.

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  23. #23
    A very stick puppy's Avatar
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    Quote Originally Posted by cubdriver2 View Post
    We had a foot or more of snow last Sunday but then the wind blew for a few days. Got to play a little today

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    Step comes in handy

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    Was having fun till freezing rain

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    Glenn

    Seldom does a week go by that I am not asked by customers and local friends "why do you enjoy that Glenn guy so much?". I think his pictures answer the question - who on the planet could not love a guy who has a 12/3 SkiDoo (okay - so it doesn't have the optional front bumper) and a turn of the century (pre 1900's) metal lawn chair along with a pristine (and well used/well cared for) pa-11 in his hangar? Add in his most recent comment about skiing in powder and I think even Joe will have to agree - Glennie is a rock star.

  24. #24
    cubdriver2's Avatar
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    You missed a couple others, like my 1965 steel chain track Artic Cat 120D. Engine was seized and every link in the track were seized tight when I got it.

    https://youtu.be/WKeS26lRNRU

    https://youtu.be/Qt6oDkzX_Nw

    https://youtu.be/zEwrEoaKDrc

    https://youtu.be/7f6y2B1IPmQ

    Glenn

    PS. And your customers questions are scaring me
    Last edited by cubdriver2; 01-05-2017 at 08:43 PM.
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  25. #25
    A very stick puppy's Avatar
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    Quote Originally Posted by cubdriver2 View Post
    You missed a couple others, like my 1965 steel chain track Artic Cat 120D. Engine was seized and every link in the track were seized tight when I got it.

    https://youtu.be/WKeS26lRNRU

    https://youtu.be/Qt6oDkzX_Nw

    https://youtu.be/zEwrEoaKDrc

    https://youtu.be/7f6y2B1IPmQ

    Glenn

    PS. And your customers questions are scaring me
    To be honest and up front, my customers scare me. But they give me money.

  26. #26
    spinner2's Avatar
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    Quote Originally Posted by Randyk View Post
    "I've got about 25 hours and perhaps as many as 300 landings on these skis"

    Wow. A landing every five minutes? Wow.
    Today was another excellent ski flying day and I decided to go back to the reservoir. Wondering if I'd overestimated how many landings I may have made out there a couple of days ago, I thought I'd time myself doing a couple of 10 set landings routines with the stop watch on my iPhone. It surprised me. The first 10 took 2 minutes 16 seconds. The second set of ten were 2:44. That's 20 landings in 5 minutes.

    These are not FAA type currency landings for a tail dragger. I takeoff and almost immediately setup for the next landing. Few of the landings are full stop. Most of the time I'm pushing in the throttle again when I've slowed to about 20 mph. Then a throttle bump and it is off again. Sometimes I'm changing from 2 notches of flaps for takeoff to 3 notches for landing. But sometimes I leave it at 2 or 3 for both. And some are done with no flaps.

    I was introduced to this type of landing routine years ago when I got a seaplane rating in a PA18. The instructor had me do landing after landing like this on the lake we were operating on. We went for miles doing this. It was fun and didn't take long to get the sight picture and procedures established this way. It is still way too much fun.

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    There is a lot of places to land out here.

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    I didnt like seeing this; laying some tracks showed overflow on the next pass. Glad I didn't stop here.

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    The overflow was in the shaded area on the far side of these islands.
    "Fast is fine, but accuracy is everything." Wyatt Earp

  27. #27
    S2D's Avatar
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    Quote Originally Posted by cubdriver2 View Post
    I'm kinda curious what that circular structure is out back at the 25 sec mark !!!!
    I may be wrong but that probably won't stop me from arguing about it.

  28. #28
    cubdriver2's Avatar
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    Quote Originally Posted by S2D View Post
    I'm kinda curious what that circular structure is out back at the 25 sec mark !!!!
    Cedar Henge

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  29. #29
    cubdriver2's Avatar
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    Used to be a large dairy barn where my hangar now sits, burned to the ground in 79. I'm stuck with a 10' deep X 20' blue harvester silo concrete foundation, I started make a ? structure out of it.

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  30. #30
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    Oh !!!! And here I thot it was an Indian sweat lodge for giant Indians !!
    I may be wrong but that probably won't stop me from arguing about it.

  31. #31
    cubdriver2's Avatar
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    Quote Originally Posted by S2D View Post
    Oh !!!! And here I thot it was an Indian sweat lodge for giant Indians !!
    It makes a good bandstand for summer hangar party's

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

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