Skis Setup

Complete newbie here.

Yes I have read 43.13 on skis and also a better article from the cub club

a few questions remaining

Springs Vs Bungee?

How long does the crust cutter section need to be?

How do those bungee ends stay on


where can you buy the hardware to make bungees or springs?


I check the websites but couldn't find anything on wag spruce or geek

http://www.aircraftspruce.com/catalog/lgpages/shockcord2.php "Shock cord" works better at Spruce for the ends, generally 1/2" is used. Jim

Springs are forever, bungees eventually wear out and lose their elasticity. With the "old" bungee material, this was essentially a non issue...the old bungees would last for a LONG time. Not these days. Whatever has happened to the material they make bungees out of these days, they don't last as long as they used to. Did I mention that springs last forever?

In extreme cold, which if your avatar is accurate (as in OK) ain't very likely, bungees can stretch out and not rebound. I wouldn't worry about that much.

Springs are NOT on the TC for any skis I'm aware of so if you do install springs, make certain to call them out on your ski installation, and field approve them to be safe.

The crust cutter need only be a foot or so, but if springs are used, it's pretty much irrelevant anyway.

MTV

Mike,
Springs are not forever. I have had two break. One was where the exhaust had blown on the spring. The other just broke on the upper hook on the spring. No corrosion or anything. Why anyone would want to save a few bucks and put screen door springs is not thinking correctly. It is no fun whatever to have a ski in the wrong position during flight.

arcticairalaska said:

Mike,
Springs are not forever. I have had two break. One was where the exhaust had blown on the spring. The other just broke on the upper hook on the spring. No corrosion or anything. Why anyone would want to save a few bucks and put screen door springs is not thinking correctly. It is no fun whatever to have a ski in the wrong position during flight.

Click to expand...

Was told metal springs get brittle in very cold weather and can break. Metal does get effected by cold more than most admit. There is a certain (very) low temp where spring metal will snap like ice. But, so will anything else. I do not fly skis. Just adding $00.02.

Mike's right on the bungees, the newer stuff is ok at best. The old bungees lasted longer and they would stretch about half of their length so a 3' bungee would stretch 18" and return to where it started. The new and improved 3' x 1/2" bungee will only travel 10" or so and the pull feels like it doubles in that 10" . so if you make the crust cutter too long the bungee gets shorter and the travel get shorter and and you need the strength of Chuck Norris to hook them up. I'm no expert on bungees but because I have a nicopress tool I'm the jerk around here that gets "stuck' making up everybodys rigging. I don't like springs on a Cub, it has nothing to do with whats best, it's a fashion statment only. So we need bungees right, 1/2" is what every one uses. If you can find the older locking spring ends all the better, the new ends are C shaped and if not taped shut after install could come off if the bungee gets slack in it as you raise the tail because the new bungees when below 10F return to original length very slowly so tape the end. The hog rings that they sell you for 1/2" spring ends also suck, if you don't get them tight on the bungee they pull off of the bungee, if you get them too tight the spring jumps the ring and pulls off of the bungee. It's a pain but I make my hog rings out of 12 penny nails you can make em tight and they are big enough to keep the spring on. Other thing I found out the hard way, if you leave the bungees hooked up in tention over night the bungee stays stretched and will very slowly pull the ski up when you take off so I unhook them when I'm done flying for the day. As far as length I make the cutters 10" long and the way I determin the bungee length is I raise the tail so that the back cables are tight ( tail about 5" higher then level flight ) and I make the bungee 5" shorter then reaching the gear fitting. One of these times I'm going to try 3/8 bungee and double it with eyes on both ends and see if it has a longer travel memory. I had to figure this out by trial and error so if any or all of you have a better way PLEASE tell us.


New


Old better style


If you have expander brakes a handy step




I used to use the dog snaps with the ring welded, now I use the chain repair link to hook to the planes tabs




Hope this helps
Glenn

May I respectfully say to use a "go, no-go" gauge on the Nicro press after the swage. "Go, No-Go"s are used in production aircraft, in case somebody does NOT close the machine all the way. Also, handy if you are flying unknown hardware too.

In picture #6 I do not see a pig tail on the swage. Pig tails help monitor slips on a swage.

I use a guage and as to the pigtails, ok on control cables but as for ski cables that I sometimes handle more then once a day around here during a fickle snow season. After the 4th or 5th time that it sticks 1/8" into my already frozen finger, they are now all flush and are going to stay that way.

Glenn

cubdriver2 said:

I use a guage and as to the pigtails, ok on control cables but as for ski cables that I sometimes handle more then once a day sometimes around here during a fickle snow season. After the 4th or 5th time that it sticks 1/8" into my already frozen finger, they are now all flush and are going to stay that way.

Glenn

Click to expand...

Thanks Glenn, you are right the pig tails will hurt. If the swage tails are flush, just "look closer" for inspection. That should be easy in direct sun light.

Thank you for guiding us wannabes.

-8GCBC

Anybody else notice in the last few years the black bungee material? Not the black rubber stuff that's been around forever, or the tan colored stuff like you and I use on our skis. I have a couple of these (hardware store bought consumer grade, but black) on the rear end of my crane, for over 3 years now, (holding down the hazard cones in their rack, to keep the port of entry pukes happy) exposed to way more UV then the plane will be in 50 years, and they have lost NONE of their elasticity and look like the day I bought them. I keep the crane under cover, but the rear end faces south, so these gets lots of sun.

When I bought my Roberts bungee/Cub style gear for my Rans S-7S last year, John pointed out that the bungees he uses is the new kind, the black stuff. I exclaimed that hell that looks like the same stuff I had already noticed holds up great in general outdoor use, so why not airplanes? It ain't just a dye job, but a different material near as I can tell, and it seems to hold up great. Check it out you guys that can go experimental, the next time you're in the bungee section of your hardware store. For now I will stick with the old style tan colored bungee that came with my Datum wheel skis, but when it's replaced I'll probably use the black stuff.

An addenum: I'm not saying go the hardware store and put them on your plane, but maybe on your farm equipment, pickup, or whatever, wait a few years like I have, and see what you think. Then see about a good OEM source for this black bungee material, whatever it is it sure seems to have "airworthy" potential for us experimental types.

Last year I called Airglas about bungees and got educated.They do not use hardware store bungee material.I was also amazed at how much pull they want.If I remember correctly it was around 80#.

Bill

I recently install some Aero skis on a Husky which came with (garage door looking) springs. I have had several of these springs break on my garage door over the years. That is without the abuse that they could get with a ski installation.

arcticairalaska said:

Mike,
Springs are not forever. I have had two break. One was where the exhaust had blown on the spring. The other just broke on the upper hook on the spring. No corrosion or anything. Why anyone would want to save a few bucks and put screen door springs is not thinking correctly. It is no fun whatever to have a ski in the wrong position during flight.

Click to expand...

Sandy,

Sorry, I should have said that springs are generally forever on MOST PEOPLE'S ski planes. Since you probably do more ski landings and takeoffs in half of one season than most do in a lifetime or two and in pretty extreme temperatures.... Obviously, anything can and will break.

I really don't trust that new bungee material much, though, having had some of those "sag" in cold temperatures.

Our Top Cub gear bungees generally last about one season before we start to notice the plane listing. Not the plane's fault, and I ain't discussing landing skills here....:roll:.

I agree that ANY metal placed in the exhaust stream of an engine is at risk and probably shouldn't be trusted for long.

I like springs, but buy them from Aero Ski, not Home Depot, though Aero Ski may get them from the same supplier.....

MTV

Ok so ended up with some skis.....i lucked out and got two of the good bungee ends and 2 newer style....These skis have a cast pylon has anybody made a ski dolly for skis that done have the extra hole?


I have a few ideas as i get time to draw them up ill pose for comments

swoeric said:

has anybody made a ski dolly for skis that done have the extra hole?

Click to expand...

something like this works well.

Dave,
what do you do about the cotter pins?

Did you make these up? I could use a pair and and of course a three-way for the bat plane. I will be at LH next week.

Rocket

Ronny!

I"ve done several production runs. The basic idea is not mine. I've simplified and optimized a few details. They're pretty simple to fab., but it is much more efficient to build 4 sets at a time rather than 1 at a time. I"m busy, don't ask me now.

for safety's..........I've used cotter keys and it's not too much hassle. I've used giant "safety pins". I've used a sort of collar/clamp like an exhaust clamp with a "stud" that catches a castellation and the hole in the gear axle. I've used a 1/8" monel rivet of suitable length with a hose clamp to hold it. I've used a "C" ring made of music wire that "springs" into place. All of these worked. Some of them on Experimental only.

I"m at KAS, as you know. LUnch?

I have a set of Atlee's 2500's. I have had springs on mine for about 17 years but then again I ain't worth a s**t as a cub pilot\ hero owner. I just fly and fish.

I bought some springs for my Datum skis, but find they are way too heavy so I'll be sticking with bungees.

Q: Do the bungee hooks have to be safety-ed to the attach points? Seems to me that hook could jump off pretty easily.

Q: Is it a good idea to use two front cables instead of one, with the second cable being just a little longer in case the primary one breaks? I've seen this arrangement on a few ski-planes.

NunavutPA-12,
This may help to answer some of your questions: http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC 43.13-2B.pdf Look at Chapter 5 starting on page 39. It is about ski installations.

The Datums use two rear cables because they keep the ski where and how needed during the retraction process. Rig it like Datum says and it will work fine. Doing it the way previous and different ski installations have done it will not be correct for the way they are designed to work.

The bungee hooks don't come off, or come unhooked. They are always under tension. If you're concerned about it safety wire them and/or simply run some electrical tape around them. Or use any kind of quick link adequate strength wise. When in the hangar I throw a block of wood under the ski tip, so the ski weight isn't pulling down on the bungee between flights.

Maybe this should be in a different thread, but a great way to pre position cable lengths for any use is to use electrical split bolts. They won't hurt the cable, grip well, and allow you to play around with cable length and then when happy with it, you then nico press the previously positioned swedge, and THEN release the split bolt.

Well, my bungees have the newer hook shape as in cubdriver2's post. Definitely don't look as if they would be very secure. Guess I'll safety them with a zip tie and some tape.

Saw a 185 last year that went through here on the way to the north pole. He had two front limit cables on his hydraulic wheel-skis, in addition to the bungee/crust cutter cable. That seemed like a good idea since loss of the front cable could ruin your day. Very little weight penalty.

We were posting at the same time!

I have the skis installed now but not yet rigged. Turns out that on my PA-12 (-18 gear) if I use the lower engine mount and the rear landing gear bolt as attach points then the front and rear cables are very close to parallel which, as you know, is essential with these skis. So, in my case, no need for that Y-arrangement in the rear.

I'm still thinking that doubling up the front limit cables might create some peace of mind.

Trickair skis is now making and selling a copy of the locking bungee spring like the old Federal ones. About 9 bucks each.

Glenn