pzinck
Registered User
western,me
F Atlee dodge sells them.
Ski Rigging Theory
- Thread starter elgoatropo
- Start date
cubdriver2
FRIEND
upstate NY
Lowes in the garage door section
Glenn
Glenn
Bearhawk Builder
FRIEND
In the woods
The Datum skis I'm installing came with a spring, looks like a garage door type. Is that really what folks use? Seems way overkill to me. Probably 3 or 4 more times the spring tension than the bungee and heavy. I'm no expert here just asking.
skywagon8a
MEMBER
SE Mass MA6
Does Dodge make his own springs? Or what is his source? Not saying that he did this, but when getting an FAA approval for something, you must prove that the part that you are using can pass certain tests. If you get a spring or a bunch of springs from Lowes and they do pass the FAA tests, the FAA will give you the approval for your application. Where do the Lowes springs originate? I'm not picking on you nanook, only making an observation based on my experience.
I've noticed in this thread that there are references to several cases of rear cable failures. Does anyone know why these cables failed? Was it the cable or the connections? Poor maintenance? I've only seen 1/8" used in these cables. Would a larger diameter have solved the problem? It doesn't seem as though there would be any loads which would require a cable diameter greater than 1/8", since the sole purpose (as far as I know) is to control the position of the ski in flight.
NunavutPA-12
FRIEND
67.8N,115.1W CYCO Canada
I asked Datum to provide some springs for my 2500's and they sent me these ridiculously heavy things that must weigh five pounds apiece. I tossed them in my junk box and went back to bungees. I might look into the Atlee Dodge springs when the bungees need replacing.
courierguy
MEMBER
Inkom, Idaho
I continue to use my original bungees that came with my Datums. I make a point a point of blocking the ski tips up in the hangar and keeping them "unloaded". Out of the sun too naturally.
Under some circumstances, those rear cables can see a lot more loads then just the inflight loads of keeping the skis oriented properly. I thought the same at first and was about to switch over from that heavy 1/8" to lighter and less draggy 3/32", until after a few hours later I noticed the thimbles on the 1/8" were elongated a bit! And that was on a 780 lb plane, rigged, as near as I can tell, properly. It's when you off level ground and boony bashing up and down drifts etc. that this seems to happen. I'm staying with 1/8" that's for sure.
Under some circumstances, those rear cables can see a lot more loads then just the inflight loads of keeping the skis oriented properly. I thought the same at first and was about to switch over from that heavy 1/8" to lighter and less draggy 3/32", until after a few hours later I noticed the thimbles on the 1/8" were elongated a bit! And that was on a 780 lb plane, rigged, as near as I can tell, properly. It's when you off level ground and boony bashing up and down drifts etc. that this seems to happen. I'm staying with 1/8" that's for sure.
My Fluidynes use bungees. They park outside all winter through freeze and thaw, sun and rain, and hold up great. But they get parked with the skis retracted almost 100% of the time so there's very little tension or stretch on them. That's different for guys with straight skis who park with the front cables in nearly full stretch. Bungees don't last so long in that case and FA Dodge springs are very popular as a solution. Dodge springs aren't approved on hydraulic skis for us certified guys but more to the point they aren't necessary.
Bearhawk Builder
FRIEND
In the woods
Yeah, that's where I'm at with these, I'll rig it with the bungees and see how they hold up.
beaver18
Registered User
Quebec Canada
Bearhawk just be carefull with the bungee make shure you buy the cold weather ones ,they are only made in the ring form if you buy it by the roll it is not cold weather been there done that, the cold weather one are made of natural latex rubber the one made with syntetic rubber will freze and loose tension ( even if you disconect them ) and you better be sure that your cable are good cause they will get used ,SBC bungee make them in any size , Trickair needed 40 lbs of pull down at the tip for the tension .
Bearhawk Builder
FRIEND
In the woods
Roger that, thanks
nanook
MEMBER
northern alaska
installed 5/32 cable (replaced 1/8") for check cables and utilized shackles inside the thimble eye to spread the load. Keeps the eye from elongating.
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nanook
MEMBER
northern alaska
been running dodge springs on hydraulic skis since they came out! Not sure what planet you are living on!
courierguy
MEMBER
Inkom, Idaho
The hang glider guys have some neat hard plastic type "donuts" that they use inside the thimble to accomplish the same thing. I've always been under the impression that a deformed thimble is a good heads up as to the loads involved, as in normal usage they won't. I should load test some 1/8" cable with the cranes load indicator to see where it the thimble deforms relative to where it snaps. It's fairly accurate, within 200 pounds anyway. My aft cables go to a under the fuselage bushing that holds a AN-4 bolt, (so shear loaded) and I used doubled up old hang glider stainless tangs I had in the junk pile, their original purpose being cable termination. They will also deform a bit way before failure, they look fine. For my light bird I'll probably stay with the 1/8" and "continue to monitor".
My bungees have worked perfectly for the 15 years I've had these skis. I asked Steve @ Atlee's about springs and he said not approved/probably not worth the effort. Certainly not worth the effort to fix what ain't broken. When I needed to re-rig my old FlyLites I couln't get the same bungees and had to remake cables for the new bungees. No problem. I know guys who have springs on Fluidynes. No biggie to me. I was just providing a pirep.
nanook
MEMBER
northern alaska
I originally ran the thimble eye through the Dodge SS tabs on the 1/8" and they almost completely cut through. The 5/32" look like new with the shackle installed. Unfortunately you have to re-rig to add the shackle. One advantage is you can leave the attach tab on the gear bolt and just pull the shackle/clevis pin to remove ski.
Dave Calkins
Registered User
Anchorage, Alaska
A HUGE advantage that I consider every time I do ski cables.
Disadvantages?........the shackles have become expensive, and loss of the pin is a possible failure point.
nanook
MEMBER
northern alaska
$15 - $20 bucks for a shackle use the drilled bolt/cotter key the nut.
cubdriver2
FRIEND
upstate NY
Threaded chain repair link. Strong, simple, safe, cheap?
Glenn
Glenn
