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Ski Springs

NunavutPA-12

FRIEND
67.8N,115.1W CYCO Canada
I asked the Datum Ski guy in Quebec to send me a couple of springs to replace the bungees. That was a couple of years ago, and he sent me a pair of (what looked like) garage door springs. Damn things must weigh ten pounds apiece! Needless to say, I never used them.

Where can I get a proper pair of springs that won't negate the weight saving of my nice Catto prop?
 
Years ago I was talking to Atlee about ski springs. He told me he had taken an older bungee to a spring shop and had them build a spring with the came amount of tension strength in all distances of extension as the bungee had. They are a little heavier, but Atlee was tired of having bungee rubber fail in cold.

Get good springs, (Atlee makes good stuff), and enjoy the long years of use.
 
Years ago I was talking to Atlee about ski springs. He told me he had taken an older bungee to a spring shop and had them build a spring with the came amount of tension strength in all distances of extension as the bungee had. They are a little heavier, but Atlee was tired of having bungee rubber fail in cold.

Get good springs, (Atlee makes good stuff), and enjoy the long years of use.
i could call and ask, but whats the difference between his gold and silver springs?
 
http://www.aeroskimfg.com/


Just like these


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Who cares what they weigh.. all I ever use. Isle #6 in Home Depot, 140lb garage door springs.
 

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Just call Atlee, DER cryin out loud. Springs rule, especially you are flying in cold weather. That’s when there’s a - sign before the temp.

MTV
 
Bungees work fine as long as you don’t leave them stretched in cold temps or transition from damp freezing temps to cold overnight temps. I used springs with straights and still use bungees with Fluidynes. Never a problem but I never leave skis down when parked. Equipment management.
 
Bungees for me on the Datum's, but it's rare, never actually, that I get below zero temps. And when in the hangar I always block up the skis to take the load off them.
 
Go fast enough in the cold under air load with G's and bungees will stretch and stay that way longer than springs. It's a choice but I want all the tension available all the time. Had Landes 2500's nose drop to the safety cable with bungees in the cold. Never with Atlee springs.

Gary
 
Gold springs are longer.

i guess i asked that question wrong. what i should have asked maybe is, why use one or the other? just like cold weather bungees for the landing gear there must be cold weather bungee in lengths.
 
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Go fast enough in the cold under air load with G's and bungees will stretch and stay that way longer than springs. It's a choice but I want all the tension available all the time. Had Landes 2500's nose drop to the safety cable with bungees in the cold. Never with Atlee springs.

Gary

Air load on the bungees? Never thought of that, but just eyeballing mine they don't appear to be under much tension while in flight, maybe it's the way I have the skis rigged, and the shape of the Datums, the way they fly/angle of attack. I'm still on my original bungees, going on 7 years, so I guess I should start thinking of replacing them, though they sure don't seem to need it, still nice and springy and mo weather checking, I know they are age limited. The next time I'm at my Lowes store I'll check out the garage door springs, something to think about. Atlee springs would be too big for my needs I'm guessing, made for heavier planes, extra weight and drag. Replacing my current bungees with exactly the same type would at least be less of an experiment, I do enough of that.

Got the winter runway, right out the hangar door, mowed in, I'm getting ready!
 

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On a Cub I'd be more concerned about location of the cable attach points than bungees vs springs. And the OP is using retractable wheel skis, so there's another wrinkle.
 
What's cold? Well below -0F so most would never have an issue. Air load from prop blast and airspeed? I guess over 125 as a rough estimate and big engine/prop. Most Cubs wouldn't qualify.

Bungee cord material was cold adaptable years ago (natural rubber to whatever it was called). Then I had some that wasn't flexible for the gear and skis so went to springs for the skis and cold weather material for the bungees. Now the cord material may be better again and flexible when chilled (?). Give them a push with your boots and see if they give and quickly return ok. Springs always will in my experience.

The OP Larry knows cold.

Gary
 
Most folks are running the part number 2097 silver springs on aircraft of your gross weight the springs are 16 ½” long . The 2127 gold springs are 19” long. Length may be a factor for your installation. The silver springs have a quicker rate of increase as they are stretched. Unfortunately the silver springs can only be stretched 9”, the gold can be stretched a little further.

(From Cliff at Atlee Dodge)
 
most folks are running the part number 2097 silver springs on aircraft of your gross weight the springs are 16 ½” long . The 2127 gold springs are 19” long. Length may be a factor for your installation. The silver springs have a quicker rate of increase as they are stretched. Unfortunately the silver springs can only be stretched 9”, the gold can be stretched a little further.

(from cliff at atlee dodge)
thanks!!
 
Thread drift I know, but ski related: I can get 50' of this USA made UV resistant black shock cord, for $37.00 and free freight. Probably less then just the customs charge from Quebec. I could re-use my original hooks, all I would need would be the right size hog rings, or is there a method using safety wire maybe, to secure the folded over end? That seems like the spooky part, making that hog ring correctly, and having faith in it. https://www.qualitynylonrope.com/1-...slbp84Qb1dYs6P6tYaarX1rZh_ZeSfEMaArSsEALw_wcB

Just found some, 1/2" hog rings, galvanized, 100 for 5 bucks. Done deal, already got the pliers for some smaller rings but think they'll work for the larger ones. I'm going to use the 40' of bungee left over to experiment with, regarding the holding power of the folded over cord secured by a hog ring method. Hold my beer.
 
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Air load on the bungees? Never thought of that, but just eyeballing mine they don't appear to be under much tension while in flight, maybe it's the way I have the skis rigged, and the shape of the Datums, the way they fly/angle of attack. I'm still on my original bungees, going on 7 years, so I guess I should start thinking of replacing them, though they sure don't seem to need it, still nice and springy and mo weather checking, I know they are age limited. The next time I'm at my Lowes store I'll check out the garage door springs, something to think about. Atlee springs would be too big for my needs I'm guessing, made for heavier planes, extra weight and drag. Replacing my current bungees with exactly the same type would at least be less of an experiment, I do enough of that.
I realize that this tread is about silver and gold springs, but your comments remind me of an accident in Canada a few years ago. A 185 on skis had a failure of the front attachment. The cable snapped forward and wrapped around the prop pulling the engine from the plane with the ski pointing straight down, with the result of tearing the plane apart. The miracle of this was that the two people who were riding in the back seat rode the aft section of fuselage to the ground and survived. The front seaters not so lucky.

My message is: Don't be casual about maintaining your skis and their attachments. ​We don't want to be reading about you in the oops thread.
 
I just heard back from the Datum head guy, and he agreed it'd be a good idea to replace mine, with the years on them. He has a pair on the way to me, and it sounds like due to my relentless cheer leading of the Datum skis, including a feature article in Kitplanes magazine a few years ago and more recently a YouTube ski flying video shot by a pro video producer friend, Jean is feeling generous towards me! Cost was never much of a factor, so even if he bills me no big deal. Best of all, now I don't have to dream up dangerous (non flying related) stunts to make use of the 40+' of the 1/2" shock cord I would have had left over from buying a 50' roll.
 
I realize that this tread is about silver and gold springs, but your comments remind me of an accident in Canada a few years ago. A 185 on skis had a failure of the front attachment. The cable snapped forward and wrapped around the prop pulling the engine from the plane with the ski pointing straight down, with the result of tearing the plane apart. The miracle of this was that the two people who were riding in the back seat rode the aft section of fuselage to the ground and survived. The front seaters not so lucky.

My message is: Don't be casual about maintaining your skis and their attachments. ​We don't want to be reading about you in the oops thread.

That accident was attributed to the old clamp-on cable attach bracket used on many Skywagons. The geometry of the front cable was bad. My 180 had those brackets installed when I bought it. The geometry of Cub rigging using a tab under the front gear bolt isn’t much better.

For you guys who use Air Glide skis on Cub gear, where does your front cable attach to the airplane? Since the skis move forward to retract I’m curious. My Skywagon’s Fluidyne tips sit forward of the prop when retracted. Rigging and attach points are inspected closely before every flight.
 
That accident was attributed to the old clamp-on cable attach bracket used on many Skywagons. The geometry of the front cable was bad. My 180 had those brackets installed when I bought it. The geometry of Cub rigging using a tab under the front gear bolt isn’t much better.

For you guys who use Air Glide skis on Cub gear, where does your front cable attach to the airplane? Since the skis move forward to retract I’m curious. My Skywagon’s Fluidyne tips sit forward of the prop when retracted. Rigging and attach points are inspected closely before every flight.

I've advocated for years to make the forward limit cable attachment to the lower engine mount on Cubs/Huskys because I REALLY don’t like the geometry of the attachment to the gear bolts.

MTV
 
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move advocated for years to make the forward limit cable attachment to the lower engine mount because I REALLY don’t like the geometry of the attachment to the gear bolts.

MTV

That's good advice. I wonder since Air Glides move forward to retract whether the STC requires a different cable fitting location? As bad as the Cessna gear fittings were they'd have been an instant disaster with Fluidynes.
 
Citabria originally had a similar geometry to Cessna - ski rigging to upper spring gear. Bad design fixed by attaching forward to lower engine mount and/or boot cowl and rear to float or ski fitting on fuselage. As a test lift the plane and step on the ski nose. If easy to depress move the rigging more vertical.

Fluidyne W/S move around in flight if rigged wrong especially if bungees used. Gets old in the cold.

Gary
 
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Don't rig 'em wrong.

I have video shot forward from under the tail of my 180 with the Fluidynes on. Rock solid except when taxiing skis up on bumpy ground.
 
We rigged at least one Husky on Fluidyne retractables, and rigged the forward limit cables to the lower engine mount bolts. Worked fine as skis moved fore and aft. Did same with Rosti Fernandez retractables on a Husky. Same, same.

MTV
 
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