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Paul A. Franz, P.E.

Joined: 02 Dec 2008
Posts: 280
Location: Bellevue WA

Posted: Sat Dec 20, 2008 10:23 pm Post subject: skis

While watching the Dave Fisher (thanks, Gary Algate) video of the KF on skis



<http://www.youtube.com/watch?v=-0COIbiwm9g>



It would appear to me that there is a great deal of sliding friction and a lack of

flotation. The ski designs all appear to be fairly rigid. From my snow skiing

experience, I would think that the skis might even be getting snow caking. It would

seem to me that they need to have more area from being longer, not wider and if they

were slightly flexible then with aileron control you could lean the plane into a turn

slightly and you would be able to turn.



Wouldn't adding length and flexibility improve flotation, reduce friction and greatly

improve maneuverability?



I know Lynn is building new skis and using vacuum bagging to build up the bases. If it

were designed as skis for powder, I'd think you'd want a length to width ratio of

about 25 with slightly wider front tips and a loading of about 1.0 lbs/in². So that

would mean for a 1200 lb aircraft with two skis, each ski would be designed for 600 lb

load and would have 600 in². Given a length to width ratio of 25 that would be mean

each ski would be 4.9" wide and 120" long and be flexible enough so that the tips

could flex up going over ruts and ridges with a loading center about 50" from the rear

tip of the ski.



Have skis of such dimensions been tried?



'Twas the nocturnal segment of the diurnal period

   preceding the annual Yuletide celebration, And

   throughout our place of residence,

Kinetic activity was not in evidence among the

   possessors of this potential, including that

   species of domestic rodent known as Mus musculus.

Hosiery was meticulously suspended from the forward

   edge of the woodburning caloric apparatus,

Pursuant to our anticipatory pleasure regarding an

   imminent visitation from an eccentric

   philanthropist among whose folkloric appellations

   is the honorific title of St. Nicklaus ...

-- 

Paul A. Franz

Registration/Aircraft - N14UW/Merlin GT

Engine/Prop - Rotax 914/NSI CAP

Bellevue WA

425.241.1618 Cell

_________________
Paul A. Franz, P.E.
Registration/Aircraft - N14UW/Merlin GT
Engine/Prop - Rotax 914/NSI CAP
Bellevue WA
425.241.1618 Cell
425.440.9505 Office

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sun Dec 21, 2008 3:45 am Post subject: skis

Here's a shot of Wipaire's Air Glide ski that I saw at Oshkosh this  

year. I'm following the basic shape of these, in designing my non- 

repositionable skis. The lower picture is of Trickair ski. I though  

that I would pattern mine with the wider front area, and with no rear  

ski area directly behind the wheel...sort of like a cross between the  

two types shown....like the Wipaire in footprint, but the other in  

being a fiberglass-covered tubing frame, like I have built before. If  

these pics don't come out in the order that I've placed then, the  

Wipaire has its name on it, the Trickair is yellow, and the other two  

pics are my skis...the one shot on snow is at Oshkosh. You can see  

how far my present skis ride above the snow, creating lots of drag.  

The next set will be MUCH lower to the ground.



 From the skis that I've seen, the measurements that I've taken, and  

calculations that I've made, 1 lb/sq. inch seems about right. I'm no  

engineer, and I pretty much  just "eyeball it" when it comes to  

designing/copying something, but then again, I don't try to sell it  

either. : )



My present skis have about 480 sq. in of area, with the wheel hole  

area removed from the overall size. I plan on shooting for 660 sq.  

in, according to a "note to self" dated 11-30-08, so I must have some  

figures somewhere in all my notes that led me to that  

conclusion. : )  I measured my CFI's 1500 Federal skis, and they came  

out to 764 sq. inches for the two skis  (64" x 6")  That comes out to  

about 2 lbs/sq. in. of loading.



I've come to the conclusion that about 15" for the front  width, and  

6" for the part that parallels the wheel will be what I'm shooting  

for. In a 60" long ski this will give me about 630 sq. in. That's my  

story and I'm stickin' to it...for now.



Oh, one more thing, Paul, I'm gonna go with the UHMW for the initial  

test of the framework/pedestal-mounting system, then work on the  

vacuum bagging/plywood bending, fiberglass-covering part later.

  

On Dec 21, 2008, at 1:22 AM, Paul Franz - Merlin GT wrote:



  (edited)

 	  Quote: 	
		   Wouldn't adding length and flexibility improve flotation, reduce  

 friction and greatly

 improve maneuverability?



 I know Lynn is building new skis and using vacuum bagging to build  

 up the bases. If it

 were designed as skis for powder, I'd think you'd want a length to  

 width ratio of

 about 25 with slightly wider front tips and a loading of about 1.0  

 lbs/in². So that

 would mean for a 1200 lb aircraft with two skis, each ski would be  

 designed for 600 lb

 load and would have 600 in². Given a length to width ratio of 25  

 that would be mean

 each ski would be 4.9" wide and 120" long and be flexible enough so  

 that the tips

 could flex up going over ruts and ridges with a loading center  

 about 50" from the rear

 tip of the ski.



 Have skis of such dimensions been tried?



 Paul A. Franz

 Registration/Aircraft - N14UW/Merlin GT

 Engine/Prop - Rotax 914/NSI CAP

 Bellevue WA

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_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sun Dec 21, 2008 9:42 am Post subject: skis

I just found some figures for ski sizes that I had measured a while  

back. This first is a Cub ski, measuring 8" x 48" for 768 sq. in for  

the two skis. The second is a Federal ski that measured 8" x 63" for  

1008 sq. inches for the two skis. I didn't happen to notice an I.D.  

plate on the Federal ski or I would have written it down. I'm  

assuming that if the Federals belonging to my CFI were a 1500's, and  

measured 6" x 63", then the 8" x 63" would be for a heavier plane.

I offer this info for those that are contemplating building skis for  

their Kitfox. As I am doing, you could get a rough idea of how big  

the skis have to be, but it would be just that...ROUGH.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 596+ hrs

Sensenich 62x46

flying again after rebuild, and new Electroair direct-fire ignition  

system;

also building a new pair of snow skis

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

akflyer

Joined: 07 May 2007
Posts: 574
Location: Soldotna AK

Posted: Sun Dec 21, 2008 10:22 am Post subject: Re: skis

The original Avid ski's are about 10" X 59".  You can go from there.



I have never seen a set of skis for a cub that were only 48" long.  My guess would be they are federals, off an old J3 or something.  No modern skis are that small ( atleast no one up here is flying any that small)  I would say alot depends on the local conditions you would be flying.  If your average snow depth is 10" and its hard pack, stay small.  If your landing in areas with 4' of powder, go big or stay home lol...

_________________
DO NOT ARCHIVE
Leonard Perry aka SNAKE
Soldotna AK
Avid "C" / Mk IV
582 (147 hrs and counting on the rebuild)
IVO IFA
Full Lotus 1450
#1 snake oil salesman since 1-22-2009

I would rather die trying to live, than to live trying not to die....

patreilly43(at)hotmail.co
Guest

Posted: Sun Dec 21, 2008 10:23 am Post subject: skis

Lynn C Are you going to have keels on the bottom similar to the yellow ski? Also C I can't see from the picture C how do the skis attach to the axle? Do they screw to both ends C or just the inboard end of the axle? The white one doesn't seem to have any mount for the outboard end of the axle.

  

 Pat Reilly

 Mod 3 582 Rebuild

 Rockford C IL



 	  Quote: 	
		   From: lynnmatt(at)jps.net

 Subject: Re: skis

 Date: Sun C 21 Dec 2008 06:38:06 -0500

 To: kitfox-list(at)matronics.com

 

 Here's a shot of Wipaire's Air Glide ski that I saw at Oshkosh this 

 year. I'm following the basic shape of these C in designing my non- 

 repositionable skis. The lower picture is of Trickair ski. I though 

 that I would pattern mine with the wider front area C and with no rear 

 ski area directly behind the wheel...sort of like a cross between the 

 two types shown....like the Wipaire in footprint C but the other in 

 being a fiberglass-covered tubing frame C like I have built before. If 

 these pics don't come out in the order that I've placed then C the 

 Wipaire has its name on it C the Trickair is yellow C and the other two 

 pics are my skis...the one shot on snow is at Oshkosh. You can see 

 how far my present skis ride above the snow C creating lots of drag. 

 The next set will be MUCH lower to the ground.

 

 From the skis that I've seen C the measurements that I've taken C and 

 calculations that I've made C 1 lb/sq. inch seems about right. I'm no 

 engineer C and I pretty much just "eyeball it" when it comes to 

 designing/copying something C but then again C I don't try to sell it 

 either. : )

 

 My present skis have about 480 sq. in of area C with the wheel hole 

 area removed from the overall size. I plan on shooting for 660 sq. 

 in C according to a "note to self" dated 11-30-08 C so I must have some 

 figures somewhere in all my notes that led me to that 

 conclusion. : ) I measured my CFI's 1500 Federal skis C and they came 

 out to 764 sq. inches for the two skis (64" x 6") That comes out to 

 about 2 lbs/sq. in. of loading.

 

 I've come to the conclusion that about 15" for the front width C and 

 6" for the part that parallels the wheel will be what I'm shooting 

 for. In a 60" long ski this will give me about 630 sq. in. That's my 

 story and I'm stickin' to it...for now.

 

 Oh C one more thing C Paul C I'm gonna go with the UHMW for the initial 

 test of the framework/pedestal-mounting system C then work on the 

 vacuum bagging/plywood bending C fiberglass-covering part later.

 

 

 


	


  [quote][b]

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sun Dec 21, 2008 1:45 pm Post subject: skis

Those "keels", although they act like keels are actually wear bars,  

that take the brunt of the wear that would otherwise occur if the  

tire should get low, or if you land hard on pavement. Yes, I'm going  

to have them on mine. Before I make the plywood and fiberglass  

bottoms, I'm going to use UHMW over the whole bottom, and then attach  

the wear bars to them. I haven't thought it completely through yet,  

but I might sandwich my "spray rails" between the bottom and the wear  

bars.

I'll post a picture or two of my pedestal mount, as far along as it  

is, in a little while.



The yellow skis (Trickair) attach to a stub axle that is bolted to  

the inboard side of the Grove landing gear. The white one...the  

Wipaire...attaches to the landing gear by (I think) either bolted on,  

or welded on, brackets. Go to  http://www.trickair.com/    to see  

their site and maybe watch the video of their skis in action. I  

haven't watched it, because my computer modem is too slow. Also, look  

again at the picture of the yellow ski. Just to the left of the ski,  

is the tubing framework that the ski is built around. It is black and  

hard to pick out because it blends in with the display rack, which is  

also black.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 596+ hrs

Sensenich 62x46

flying again after rebuild, and new Electroair direct-fire ignition  

system;

also building a new pair of snow skis





On Dec 21, 2008, at 1:22 PM, patrick reilly wrote:



 	  Quote: 	
		   Lynn, Are you going to have keels on the bottom similar to the  

 yellow ski? Also, I can't see from the picture, how do the skis  

 attach to the axle? Do they screw to both ends, or just the inboard  

 end of the axle? The white one doesn't seem to have any mount for  

 the outboard end of the axle.



 Pat Reilly

 Mod 3 582 Rebuild

 Rockford, IL

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sun Dec 21, 2008 1:56 pm Post subject: skis

The 48" skis were on a Cub, but whether they were original or not, I  

didn't ask. They are about 3/4" plywood for the bottom, which has  

very little curve-up, another 3/4" shorter board for stiffening, and  

used a stamped sheet metal tapered tubular pedestal that slipped over  

the axle, in place of the wheel. When I flew over to where this Cub  

was visiting, he had been on the ground for some time, and when he  

tried to leave, we had to rock his wings to break him loose, as he  

had been frozen down. I always stand on the tips of my skis before I  

get into the plane. Of course, his are plywood, and mine are UHMW, so  

his will stick before mine, especially if he hasn't waxed  

them....I've never waxed mine, and maybe I should....might help.



If we EVER get 4' of anything down here, I'm in front of the  

fire...screw the flying!



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 596+ hrs

Sensenich 62x46

flying again after rebuild, and new Electroair direct-fire ignition  

system;

also building a new pair of snow skis





On Dec 21, 2008, at 1:23 PM, akflyer wrote:



 	  Quote: 	
		   



 The original Avid ski's are about 10" X 59".  You can go from there.



 I have never seen a set of skis for a cub that were only 48" long.   

 My guess would be they are federals, off an old J3 or something.   

 No modern skis are that small ( atleast no one up here is flying  

 any that small)  I would say alot depends on the local conditions  

 you would be flying.  If your average snow depth is 10" and its  

 hard pack, stay small.  If your landing in areas with 4' of powder,  

 go big or stay home lol...



 --------

 DO NOT ARCHIVE

 Leonard Perry

 Soldotna AK

 Avid &quot;C&quot; / Mk IV

 582 IVO IFA

 Full Lotus 1260

 As done as any plane will ever be.... cause now the tinkeritis  

 takes over.



 hander outer of humorless darwin awards





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 20410#220410

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sun Dec 21, 2008 3:02 pm Post subject: skis

Pat-

Here are the pictures of the pedestal parts that I've built so far,  

and a mockup of the proposed ski using 3/4" wood where 4130 round  

tubing and flat plate will be. As you can see, the 4 holes in the  

"stub axle" will bolt up to the back side of the Grove gear. If I  

choose to leave this stub axle in place all year long...with suitable  

fairing made of fiberglass....installation will be simply sliding the  

ski onto the axle and securing the nut and cotter pin, and attaching  

all the safety cables, etc., ...and praying for snow.

On Dec 21, 2008, at 1:22 PM, patrick reilly wrote:



 	  Quote: 	
		   Lynn, Are you going to have keels on the bottom similar to the  

 yellow ski? Also, I can't see from the picture, how do the skis  

 attach to the axle? Do they screw to both ends, or just the inboard  

 end of the axle? The white one doesn't seem to have any mount for  

 the outboard end of the axle.



 Pat Reilly

 Mod 3 582 Rebuild

 Rockford, IL

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_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Fox5flyer
Guest

Posted: Mon Dec 22, 2008 12:18 pm Post subject: skis

Lynn, STOP PRAYING!  We've got enough snow.

Deke



---

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Mon Dec 22, 2008 1:35 pm Post subject: skis

Ha, Ha...you might be right, Deke. I got stuck in the drive to the  

hangar today, and when unstuck, I was too pooped to participate in  

flying. Tomorrow maybe...

It's a shame, too, because even at 9 degrees above zero F, the engine  

in my Kitfox reported a toasty 106 F oil temp, and 65° F head  

temp...it was just beggin' to be lit up!

You guys who are building, keep up the good work...you guys who live  

where there's snow and don't have skis, I would suggest strongly to  

get some and enjoy winter flying...it's fun!



Oh, by the way, I just got around to adding up the hours in my  

logbook, and last Thursday, I reached my 500th hour of solo flight.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 596+ hrs

Sensenich 62x46

flying again after rebuild, and new Electroair direct-fire ignition  

system;

also building a new pair of snow skis





On Dec 22, 2008, at 3:18 PM, fox5flyer wrote:



[quote] 

 <fox5flyer(at)idealwifi.net>



 Lynn, STOP PRAYING!  We've got enough snow.

 Deke



 ---

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

akflyer

Joined: 07 May 2007
Posts: 574
Location: Soldotna AK

Posted: Tue Dec 23, 2008 6:14 am Post subject: Re: skis

 	  Paul A. Franz, P.E. wrote: 	
		  While watching the Dave Fisher (thanks, Gary Algate) video of the KF on skis



<http>



It would appear to me that there is a great deal of sliding friction and a lack of

flotation. The ski designs all appear to be fairly rigid. From my snow skiing

experience, I would think that the skis might even be getting snow caking. It would

seem to me that they need to have more area from being longer, not wider and if they

were slightly flexible then with aileron control you could lean the plane into a turn

slightly and you would be able to turn.



Wouldn't adding length and flexibility improve flotation, reduce friction and greatly

improve maneuverability?



I know Lynn is building new skis and using vacuum bagging to build up the bases. If it

were designed as skis for powder, I'd think you'd want a length to width ratio of

about 25 with slightly wider front tips and a loading of about 1.0 lbs/inï¿½. So that

would mean for a 1200 lb aircraft with two skis, each ski would be designed for 600 lb

load and would have 600 inï¿½. Given a length to width ratio of 25 that would be mean

each ski would be 4.9" wide and 120" long and be flexible enough so that the tips

could flex up going over ruts and ridges with a loading center about 50" from the rear

tip of the ski.



Have skis of such dimensions been tried?



'Twas the nocturnal segment of the diurnal period

   preceding the annual Yuletide celebration, And

   throughout our place of residence,

Kinetic activity was not in evidence among the

   possessors of this potential, including that

   species of domestic rodent known as Mus musculus.

Hosiery was meticulously suspended from the forward

   edge of the woodburning caloric apparatus,

Pursuant to our anticipatory pleasure regarding an

   imminent visitation from an eccentric

   philanthropist among whose folkloric appellations

   is the honorific title of St. Nicklaus ...

-- 

Paul A. Franz

Registration/Aircraft - N14UW/Merlin GT

Engine/Prop - Rotax 914/NSI CAP

Bellevue WA

425.241.1618 Cell 	




would be a neat trick trying to rig them and keeping the cables out ofthe prop.  Would be a bit silly to have 12 foot long ski's.  If yer gonna do that, just use full lotus floats.

aviateer

Joined: 08 Aug 2008
Posts: 23

Posted: Tue Dec 23, 2008 6:34 am Post subject: skis

Hello,

  

 I designed and built these aluminum skis (see attached photos) with small 6" plastic-rubber castor wheels attached. They are 12" wide and 48" long. I can land on snow or pavement, and they do very well in 12" powder. The castors are semi hard rubber (I think they are 75 Durometer) and they only stick through the ski about 1". So, the profile drag in the powder is almost non-existent.

   

 I can take more pictures if anyone is interested in this design.

  

 Just my 2 cents.

  

 Thanks,

  

 Kirk

  

 



 

 On Tue, Dec 23, 2008 at 8:14 AM, akflyer <akflyer_2000(at)yahoo.com (akflyer_2000(at)yahoo.com)> wrote:

 [quote]--> Kitfox-List message posted by: "akflyer" <akflyer_2000(at)yahoo.com (akflyer_2000(at)yahoo.com)>

 



Paul A. Franz, P.E. wrote:

 	  Quote: 	
		   While watching the Dave Fisher (thanks, Gary Algate) video of the KF on skis



 It would appear to me that there is a great deal of sliding friction and a lack of

 > flotation. The ski designs all appear to be fairly rigid. From my snow skiing
	


 	  Quote: 	
		   experience, I would think that the skis might even be getting snow caking. It would

 seem to me that they need to have more area from being longer, not wider and if they

 > were slightly flexible then with aileron control you could lean the plane into a turn
	


 	  Quote: 	
		   slightly and you would be able to turn.



 Wouldn't adding length and flexibility improve flotation, reduce friction and greatly

 > improve maneuverability?
	


 	  Quote: 	
		  

 I know Lynn is building new skis and using vacuum bagging to build up the bases. If it

 were designed as skis for powder, I'd think you'd want a length to width ratio of

 > about 25 with slightly wider front tips and a loading of about 1.0 lbs/inï¿½. So that
	


 	  Quote: 	
		   would mean for a 1200 lb aircraft with two skis, each ski would be designed for 600 lb

 load and would have 600 inï¿½. Given a length to width ratio of 25 that would be mean

 > each ski would be 4.9" wide and 120" long and be flexible enough so that the tips
	


 	  Quote: 	
		   could flex up going over ruts and ridges with a loading center about 50" from the rear

 tip of the ski.

 >
	


 	  Quote: 	
		   Have skis of such dimensions been tried?



 'Twas the nocturnal segment of the diurnal period

    preceding the annual Yuletide celebration, And

    throughout our place of residence,

 > Kinetic activity was not in evidence among the
	


 	  Quote: 	
		      possessors of this potential, including that

    species of domestic rodent known as Mus musculus.

 Hosiery was meticulously suspended from the forward

 >    edge of the woodburning caloric apparatus,
	


 	  Quote: 	
		   Pursuant to our anticipatory pleasure regarding an

    imminent visitation from an eccentric

    philanthropist among whose folkloric appellations

 >    is the honorific title of St. Nicklaus ...
	


 	  Quote: 	
		   --

 Paul A. Franz

 Registration/Aircraft - N14UW/Merlin GT

 Engine/Prop - Rotax 914/NSI CAP

 Bellevue WA

 425.241.1618 Cell

 
	




would be a neat trick trying to rig them and keeping the cables out ofthe prop.  Would be a bit silly to have 12 foot long ski's.  If yer gonna do that, just use full lotus floats.



--------

DO NOT ARCHIVE

 Leonard Perry

Soldotna AK

Avid "C" / Mk IV

582 IVO IFA

Full Lotus 1260

As done as any plane will ever be.... cause now the tinkeritis takes over.



hander outer of humorless darwin awards

 



Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=220727#220727



 



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patreilly43(at)hotmail.co
Guest

Posted: Tue Dec 23, 2008 8:21 am Post subject: skis

Kirk, Neat skis. Can you take close ups of the skis and mounting? 

  

 Pat Reilly

 Mod 3 582 Rebuild

 Rockford, IL

   

 Date: Tue, 23 Dec 2008 08:33:25 -0600

From: aviateer(at)gmail.com

To: kitfox-list(at)matronics.com

Subject: Re: Kitfox-List: Re: skis

 Hello,

  

 I designed and built these aluminum skis (see attached photos) with small 6" plastic-rubber castor wheels attached. They are 12" wide and 48" long. I can land on snow or pavement, and they do very well in 12" powder. The castors are semi hard rubber (I think they are 75 Durometer) and they only stick through the ski about 1". So, the profile drag in the powder is almost non-existent.

  

 I can take more pictures if anyone is interested in this design.

  

 Just my 2 cents.

  

 Thanks,

  

 Kirk

  

 



 

 On Tue, Dec 23, 2008 at 8:14 AM, akflyer <akflyer_2000(at)yahoo.com (akflyer_2000(at)yahoo.com)> wrote:

  	  Quote: 	
		  --> Kitfox-List message posted by: "akflyer" <akflyer_2000(at)yahoo.com (akflyer_2000(at)yahoo.com)>

Paul A. Franz, P.E. wrote:

 	  Quote: 	
		   While watching the Dave Fisher (thanks, Gary Algate) video of the KF on skis



 It would appear to me that there is a great deal of sliding friction and a lack of

 flotation. The ski designs all appear to be fairly rigid. From my snow skiing

 experience, I would think that the skis might even be getting snow caking. It would

 seem to me that they need to have more area from being longer, not wider and if they

 were slightly flexible then with aileron control you could lean the plane into a turn

 slightly and you would be able to turn.



 Wouldn't adding length and flexibility improve flotation, reduce friction and greatly

 improve maneuverability?



 I know Lynn is building new skis and using vacuum bagging to build up the bases. If it

 were designed as skis for powder, I'd think you'd want a length to width ratio of

 about 25 with slightly wider front tips and a loading of about 1.0 lbs/inï¿½. So that

 would mean for a 1200 lb aircraft with two skis, each ski would be designed for 600 lb

 load and would have 600 inï¿½. Given a length to width ratio of 25 that would be mean

 each ski would be 4.9" wide and 120" long and be flexible enough so that the tips

 could flex up going over ruts and ridges with a loading center about 50" from the rear

 tip of the ski.



 Have skis of such dimensions been tried?



 'Twas the nocturnal segment of the diurnal period

    preceding the annual Yuletide celebration, And

    throughout our place of residence,

 Kinetic activity was not in evidence among the

    possessors of this potential, including that

    species of domestic rodent known as Mus musculus.

 Hosiery was meticulously suspended from the forward

    edge of the woodburning caloric apparatus,

 Pursuant to our anticipatory pleasure regarding an

    imminent visitation from an eccentric

    philanthropist among whose folkloric appellations

    is the honorific title of St. Nicklaus ...

 --

 Paul A. Franz

 Registration/Aircraft - N14UW/Merlin GT

 Engine/Prop - Rotax 914/NSI CAP

 Bellevue WA

 425.241.1618 Cell


	




would be a neat trick trying to rig them and keeping the cables out ofthe prop.  Would be a bit silly to have 12 foot long ski's.  If yer gonna do that, just use full lotus floats.



--------

DO NOT ARCHIVE

Leonard Perry

Soldotna AK

Avid "C" / Mk IV

582 IVO IFA

Full Lotus 1260

As done as any plane will ever be.... cause now the tinkeritis takes over.



hander outer of humorless darwin awards





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http://forums.matronics.com/viewtopic.php?p=220727#220727



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kitfox(at)bresnan.net
Guest

Posted: Tue Dec 23, 2008 9:18 am Post subject: skis

Kirk , they look very interesting .May I request a  couple of close up pictures .

 DeWayne at kitfox(at)bresnan.net (kitfox(at)bresnan.net)

 [quote]   ---

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Tue Dec 23, 2008 9:46 am Post subject: skis

Looks like 4 wheels total, and about 1152 sq. in. total of surface  

area. Looks like the tail end is flat...any problem dragging it  

backwards in snow? The bottom looks to be more than 1/4" thick...is it?



Good looking skis, Kirk.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 596+ hrs

Sensenich 62x46

flying again after rebuild, and new Electroair direct-fire ignition  

system;

also building a new pair of snow skis

On Dec 23, 2008, at 9:33 AM, Kitfoxkirk wrote:



 	  Quote: 	
		   Hello,



 I designed and built these aluminum skis (see attached photos) with  

 small 6" plastic-rubber castor wheels attached. They are 12" wide  

 and 48" long. I can land on snow or pavement, and they do very well  

 in 12" powder. The castors are semi hard rubber (I think they are  

 75 Durometer) and they only stick through the ski about 1". So, the  

 profile drag in the powder is almost non-existent.



 I can take more pictures if anyone is interested in this design.



 Just my 2 cents.



 Thanks,



 Kirk

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

aviateer

Joined: 08 Aug 2008
Posts: 23

Posted: Tue Dec 23, 2008 11:32 am Post subject: skis

I will try to get some detailed pictures this weekend and send them out.

  

  

 Kirk

 On Tue, Dec 23, 2008 at 11:07 AM, DeWayne Clifford <kitfox(at)bresnan.net (kitfox(at)bresnan.net)> wrote:

 [quote]  Kirk , they look very interesting .May I request a couple of close up pictures .

 DeWayne at kitfox(at)bresnan.net (kitfox(at)bresnan.net)

 [quote]  

  ---

Fox5flyer
Guest

Posted: Tue Dec 23, 2008 12:56 pm Post subject: skis

Great looking skis, Kirk and good  craftsmanship!  Am I interpreting this correctly that the entire ski  rides on the little wheel in the center?  How does it do on a grass  strip?  Is that 1/2 plastic (UHMW) and where did you find it?  Ever  thought of marketing them?

 I'm impressed.

  

 Deke Morisse

Mikado Michigan

S5/Subaru/CAP  402+ TT

"The aim of an argument or discussion should not be victory, but  progress."

- Joseph Joubert

  

 

 

  

  

 [quote]   ---

aviateer

Joined: 08 Aug 2008
Posts: 23

Posted: Tue Dec 23, 2008 7:46 pm Post subject: skis

 

 There are two wheels in tandem like a roller blade. I wanted only two wheels, otherwise one would not be able to turn the plane on pavement. Since these pictures I posted (taken in 2004),  I purchased better wheels. The wheels I now have are 6" in diameter, and 2" wide. They are rounded so the profile is very small. As I stated earlier, the skis do very well in powder snow. I was at a grass strip with about 12" to 18" of tight powder snow, and the skis worked very well. I was off the ground in the same time as I would be on packed snow. When I shut down, I dug down into the snow to check how deep I sank and found that I went down about half the depth of snow (about 6" to 8" down). My prop was still well out of the snow. I made the skis a little tall because I wanted to keep the prop out of the snow as much as possible. 

   

 The wheels in the ski were designed for pavement use. That is why I wanted a non-pneumatic wheel. I did not want to have any suspension to give and allow the ski to plant on a hard landing to pavement. This would cause the skis to grab the pavement and flip the plane over on its top. Not a good time! The idea was to have only 1" of wheel penetrating the ski. This would provide a very small profile in powder snow. In packed snow, the wheels act like a skeg to a degree. They almost give me directional authority while taxiing on hard packed snow. 

   

 I do not believe the wheels would do very good on soft grass. As I stated, the profile is very small, and that was to allow landings on snow or pavement without any device to move the wheels up or down. I think in soft grass the wheels would sink in and you would be ski on sod. Even the UHMW polyethylene does not do so well on dry grass.

   

 I made the ski bottoms out of UHMW polyethylene that I purchased from Minnesota plastics about 10 years ago. I don't know if they are still in business, but a google search would turn up some supplier I'm sure. The bottoms were suppose to be .250", but I think these are closer to .500".

   

 The skis are a little heavy at about 19lbs each. But, they have been tested. I slammed my Classic IV into the paved runway pretty hard, not by choice, but by poor execution of a landing on a windy day. When I conducted a post flight inspection, there were no cracks or bends of any kind. When I designed the frame of the ski, I placed it in my 20 ton press and cranked on it with a 400 lb scale under it. I reached the 400 lbs on the scale and went a little more. There was no bending or deformation. The wheels are rated at 650lb static, and I think several thousand pound point load for one or two seconds. I have four wheels, so there is no overload there.

   

 As I stated earlier, I will get some more photos on line in a few days.  

  

  

 Thanks,

  

  

 Kirk

 On Tue, Dec 23, 2008 at 2:54 PM, fox5flyer <fox5flyer(at)idealwifi.net (fox5flyer(at)idealwifi.net)> wrote:

 [quote]  Great looking skis, Kirk and good craftsmanship!  Am I interpreting this correctly that the entire ski rides on the little wheel in the center?  How does it do on a grass strip?  Is that 1/2 plastic (UHMW) and where did you find it?  Ever thought of marketing them?

  I'm impressed.

  

 Deke Morisse

Mikado Michigan

S5/Subaru/CAP 402+ TT

"The aim of an argument or discussion should not be victory, but progress."

- Joseph Joubert

  

 

 

  

  

 [quote]  ---

Fox5flyer
Guest

Posted: Wed Dec 24, 2008 7:12 am Post subject: skis

Great commentary, Kirk.  Thanks for  sharing.  A lot of the folks on this list never see snow and have little  use for this ski stuff, but for those of us that do, I'm finding it a  treasure of information.  I have a set of Federal 1500s for my S5, but I  think I can do much better.  All it takes is a little bit of information  here, a little there, some inspiration, tinkering, and away we go.  I don't  think there is any big mystery or magic about making a good set of skis.   Just some imagination, common sense, some work, and the fun begins.   

 Awaiting those photos.

 Deke Morisse

Mikado Michigan

S5/Subaru/CAP  402+ TT

"The aim of an argument or discussion should not be victory, but  progress."

- Joseph Joubert

  

 do not archive

  

 ---

Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Fri Dec 26, 2008 1:03 am Post subject: Skis

On Dec 25, 2008, at 11:53 AM, akflyer wrote:

 	  Quote: 	
		   The ski bottoms are NOT stepped, they are flat.


	


As far as I understand, the step on a seaplane pontoon is there to ventilate the water aft of it and give less drag. I agree, it doesn't make very much sense in the snow.



Cheers,

Michel Verheughe

Norway

Kitfox 3 - Jabiru 2200 ... flying as PAX



<pre><b><font size  color="#000000" face="courier new,courier">

_________________
Kitfox 3 - Jabiru 2200

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