WANTED!!! need to have a pair of skis built

gradguy · Post by **gradguy** » Sat Jan 01, 2011 1:05 pm

HI,

I need a pair of skis built for a graduate research project.

The skis are actually drone aircraft which weighs about 20lbs. Currently the wheel system completely fails in snow. As such I've been desperately searching for a ski solution.

I have researched using, kids skis, both downhill and XC skis and all are generally too heavy and or over built for the required application.

The second issue is even the lightest XC skis couldn't be used because of the built in camber.

I'm looking for basic ski that is 3.5ft long 3in wide and is as light as possible.

The ski wouldn't need binding inserts, sidewalls, edges, camber or shaped profile.

literally the skis just need to float on top of snow and that's it.

I have/am considering making them myself, but it will likely be more efficient if I could partner with somebody who already has the skills, knowledge and hardware to layup a set.

Does anybody have any interest in helping out?

MontuckyMadman · Post by **MontuckyMadman** » Sat Jan 01, 2011 1:33 pm

this would be really easy. Unfortunately I don't have a ton of time right now.
What is your time frame? And your budget, cause they wont be free.
What is your location?
I am thinking poplar, at 2mm thick and some glass top and bottom with base.
Prolly want a good tip rise for landing even some rocker for deeper snow.
Will the drone land on harder snow or pow?

That pvc foam shit would be good for a core prolly. I don't use that.
Aspen wold be the lightest wood possible.
Will you need a profile to sink screws in or could it be flat, and you will use a metal plate to mount to?

Richuk · Post by **Richuk** » Sat Jan 01, 2011 1:53 pm

Closed cell PVC board should allow you to mock up a design - easy to cut by hand and bends with a bit of heat. You can run a few tests, get happy with the design before getting someone to make a more presentable solution for you. Do you have a design in mind?

Brazen · Post by **Brazen** » Sat Jan 01, 2011 4:01 pm

I'd probably use a titanal honeycomb/glass/carbon fiber system.

twizzstyle · Post by **twizzstyle** » Sat Jan 01, 2011 7:08 pm

Where are you located? This is a fast/easy project, you shouldn't need to over-think it.

If it were me I'd do a foam core, uni-CF top and bottom skin, and that's it. Maybe kevlar for the bottom if you think there might be rocks where you're landing.

gradguy · Post by **gradguy** » Sat Jan 01, 2011 8:49 pm

Twizzstyle, I live in Wisconsin. Unlike Montana where I used to live. The snow here is variable at best. I would think the skis would encounter some rocks during tests, but surely I wouldn't aim for them.

I was thinking some form or carbon fiber would be used... but again ski construction is a totally new topic for me. Four weeks ago I hadn't even thought about skis as part of my research.

gradguy · Post by **gradguy** » Sat Jan 01, 2011 8:56 pm

Richuk wrote:Closed cell PVC board should allow you to mock up a design - easy to cut by hand and bends with a bit of heat. You can run a few tests, get happy with the design before getting someone to make a more presentable solution for you. Do you have a design in mind?

not really! Ski design is pretty foreign... I would think the ski tips would look like traditional downhill tips, possibly close to JR sized skis. The width is around 3" and 3.5ft long maybe 4ft. Because the skis don't need any camber or have any inserts I could trim the back of the ski for its final length easy enough.

twizzstyle · Post by **twizzstyle** » Sat Jan 01, 2011 9:08 pm

Since they aren't used for anything other than support for the airplane, you don't need to worry about torsional stiffness at all (so you don't need triax). They don't even need to be stiff, they just need to be tough so they can take the impact of a hard landing, and you want a core that won't buckle/crush under bending.

You could probably get by with just a simple balsa core too, I just think a foam core could be lighter.

Have any pictures of the airplane? (I'm an aeronautical engineer by profession, ski-builder by hobby, so I'm really curious about your project now

)

wingworks · Post by **wingworks** » Mon Jan 03, 2011 3:16 pm

sounds like a fun project
we are gearing up to make some light supercub wheel penetration skis

most of the skiplanes we operate have poor design (old school ) skis
in they load up with snow and change your center of gravity and pull down on the springs or shock cords that hold the tips up ----very heavy with 4" slush load
build the tops to shed snow and wax the tops-----use a white color as the dark paint warms up and sticks ---

to keep the skis from catching in a crosswind landing or tight turn build the bottoms non flat from side to side or curl the side edges up and put a small keel in center to help track and deflect rocks------
rig safty cables to limit tip drop to at 3 point attitude the tip cannot be pushed below the point where it will not able to dig itself out

rig rear cable so ski bottom is slightly more angle of attack than landing attitude
hope this helps

gradguy · Post by **gradguy** » Tue Jan 04, 2011 2:45 pm

Thanks everybody... I'm going to give a shot. I've ordered up materials and should know shortly after everything arrives if the skis will work. The simple nature of these skis should make the layup fairly easy.

Again thanks for all the input and offers..

I'll be sure to post my results.

Cheers

twizzstyle · Post by **twizzstyle** » Tue Jan 04, 2011 5:45 pm

Nice, good luck dude! You can expect everyone here will want pictures of your success (or failure!)

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WANTED!!! need to have a pair of skis built

WANTED!!! need to have a pair of skis built