Landes 2500 rigging for 3 inch gear

[cubpilot2]

Ok. So I know that this has been discussed before but darned if I can find it.

My skis have good PA-18 rigging for standard length gear; but the new cub has 3 inch.

Does someone have the longer cable length dimensions to change the rigging?

Landes L2500s.

Thanks

 

[mike mcs repair]

http://www.fadodge.com/fad_pdfs/ski rigging.pdf

Depending on who’s gear can get different lengths. Best to do it this way




Sent from my iPhone using SuperCub.Org

 

[DENNY]

It seems every cub/gear/ski is different, he best thing to do is find a way to hang the cub and fit the skis to the plane. You need new cables anyway so just make them when the plane is in the air. Angles and dangles are noted below.

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC 43.13-2B.pdf

DENNY

 

[DENNY]

DAMM!! Mike beat me to it. His was is even easier.
DENNY

 

[cubpilot2]

Thanks: I’m aware of how to do it, but right now she’s sitting in a cold snow bank with no real easy way to set it up.
I may give Landes a call and see if they will share any info.

I know they sell replacement rigging sets so there is a “standard” for each application.

Mike: are you saying that a three inch Atlee gear could be different length then one from Airframes ?

 

[TurboBeaver]

Ed,
Assuming your front cables wont let skis tip down over 10
degrees, if you want rig them outside in the COLD: A quick and dirty way, is just grab your digital level and lift the tail up to till your level( barrel) with your DL resting between throttles,
Have one new rear cable already nicopressed on a tab attached to rear of ski, have top nico sleave slightly pinched but so you can still slip it. Install top tab on rear bolt. Now simply raise the tail another 1.5 degrees, PAST level, and then singe the cable as tight as you can and crimp it. Now remove that one and go Inside ,and make another one exactly the same and your DONE....( Atlees old 2x4 with two nails still makes a great jig) This way both sides are exactly the same from outside tab holes .
This is not as accurite as on a hanger floor, heat at 75 degrees, listening to music https://youtu.be/kuq7RYQ8Wa0 with the skis off the floor, and plumb bob in the door frame . But it "is darn close" . Here is one that was done by A&P that way recently; to rig a Cruiser to Fed 1500's that had Citabria cables......... 5 above zero, that day, he was. done in 20mins. 103 mph at 2400 with a 74" short prop.Too bad the Pedestal height on most skis is patheticly LOW...... So AOA is nowhere near what it should be, but. Here it is in 15" of snow, with half tanks.Aprox 300' from cameraman.
https://www.dropbox.com/s/ihvti6spk3sock4/20181220_122109.mp4?dl=0

 

[cubpilot2]

Ed,
Assuming your front cables wont let skis tip down over 10
degrees, if you want rig them outside in the COLD: A quick and dirty way, is just grab your digital level and lift the tail up to till your level( barrel) with your DL resting between throttles,
Have one new rear cable already nicopressed on a tab attached to rear of ski, have top nico sleave slightly pinched but so you can still slip it. Install top tab on rear bolt. Now simply raise the tail another 1.5 degrees, PAST level, View attachment 40402and then singe the cable as tight as you can and crimp it. Now remove that one and go Inside ,and make another one exactly the same and your DONE....( Atlees old 2x4 with two nails still makes a great jig) This way both sides are exactly the same from outside tab holes .
This is not as accurite as on a hanger floor, heat at 75 degrees, listening to music https://youtu.be/kuq7RYQ8Wa0 with the skis off the floor, and plumb bob in the door frame . But it "is darn close" . Here is one that was done by A&P that way recently; to rig a Cruiser to Fed 1500's that had Citabria cables......... 5 above zero, that day, he was. done in 20mins. 103 mph at 2400 with a 74" short prop. Pedestal height on skis is patheticly LOW...... So AOA is nowhere near what it should be, but. Here it is in 15" of snow, with half tanks.Aprox 300' from cameraman.
https://www.dropbox.com/s/ihvti6spk3sock4/20181220_122109.mp4?dl=0

Thank You
Thats almost exactly what is on the plan for today unless something gets in the way......
i been waiting for the right help to handle the tail. The wife’s sporting blood just ain’t what it used to be. Something about snow and cold and her 64th birthday. ��

Lake Hood just opened for skis and for the last several days the Lake Hood strip has only been open for ski equipped aircraft.

 

[skukum12]

Quick and dirty will work, but do your best to get inside to a flat floor if you can and make custom left and right cables. I purchased new penetration skis years back that came with rigging...hindsight tells me now that I should have measured the check cables first. I was a very green pilot however and assumed they would be same/correct.

Picture piano keys, one down and the next up. That will give you a good idea of what my skis looked like in flight.

 

[mike mcs repair]

Thanks: I’m aware of how to do it, but right now she’s sitting in a cold snow bank with no real easy way to set it up.
I may give Landes a call and see if they will share any info.

I know they sell replacement rigging sets so there is a “standard” for each application.

Mike: are you saying that a three inch Atlee gear could be different length then one from Airframes ?

absolutely could be... shock strut lengths very between brands..

 

[TurboBeaver]

Considering that 75 percent of skis I see on light airplanes are normally rigged
WAY to high in the front, adversely reducing cruise. So getting them set correctly, is obviously important. However; look across these ( done QnD method) and see if they appear different to you........ I ran 2500's for 10 years on my 12 back in the 90's and they are great skis!
Good Luck
E

 

[BC12D-4-85]

Watch the cable end thimbles for stretch when on skis. If they do then the cables are subjected to high tension when climbing or descending terrain. Adjust longer as required.

Gary

 

[skywagon8a]

View attachment 40414

Question? These skis are obviously rigged perfectly for minimum drag in flight. When on skis most of us use the opportunity to land anywhere there is enough space to get in and out. Now when we land in a rolling field or where there are drifts the skis have to rock up and down following the surface. Suppose that this surface is such that it takes a long run to get airborne and you need to have the plane level in order to accelerate. While these skis are articulating up and down sometimes rather abruptly, what is happening to the rear cable when it gets to the end of it's travel? Seems to me that it wouldn't take much abuse for there to be a failure. Then, depending on the type of plane the ski could end up in an undesirable position.

Would it not be a good idea to have a spring in the rear cable to hold the ski flat in flight and still allow it to be unrestricted in it's travel? Installation instructions don't show this idea. Yet they do show the front of the ski pitched up which reduces the possibility for this potential failure.

Gary's comment on the stretching thimbles indicates this abrupt hit on the cables.

 

[supercrow]

View attachment 40414 Considering that 75 percent of skis I see on light airplanes are normally rigged
WAY to high in the front, adversely reducing cruise. So getting them set correctly, is obviously important. However; look across these ( done QnD method) and see if they appear different to you........ I ran 2500's for 10 years on my 12 back in the 90's and they are great skis!
Good Luck
E

Left one is slightly lower in the front, but certainly a decent job is only used on flat surfaces.

 

[TurboBeaver]

Pete,
That is an excellent suggestion! A spring on rear cable could remedy about any situation. These skis are rigged to Atlee Dodges published instructions for up angle. 1.5 degrees. And 9 degrees down. But I do think a good stiff spring, on the rear cable is an excellent idea! May have to investigate that possibilty in near future........
Reid; I think that is more paralex from camera angle. When we took movie of it coming "straight at the camera" they actually look darn close! Certainly as close as 99 percent as what we see. Kinda interesting folks have been flying around for years with their skis 5 degrees to high and that was just the norm, hey what ever floats your boat!
These are rigged right to spec.

 

[BC12D-4-85]

There's some reasons fixed skis are rigged with a rear limit cable. In my experience once they reach their up limit it tends to lift the plane and prop out of deep snow and frozen crust - a potential benefit for takeoff. If rigged too nose up the skis tend to rise and plow through deep snow, not lift the plane enough, and cause drag that slows takeoff. A prop tip buried in snow is useless. Once airborne if too nose up the nose wants to climb in the air as speed increases and more down trim is required. Cruise speed and flight range can suffer. I've fussed with that angle. And the more the skis are turned up during manufacture the worse it gets.

The downside is potential stress on the rear cable if rigged flat. The thimbles are the first to show that as they deform and stretch. Having a strong spring interlaced in the safety cable (or separate with it's own) might reduce stress but the stretch should be limited for the reasons noted above.

Some wheel ski manufacturers have incorporated springs in the rigging or tunnel to accommodate changes in angles during action.

So I guess experiment but try it in all conditions like rough moguls and deep soft snow.

The previous owner of my Taylorcraft had a left Aero 2000 rear cable let go. The nose rose until it touched the lift strut. He was able to land at Lake Hood strip and correct the issue. Sometimes they'll roll forward on landing or a leg can be extended to force them down.

Gary

 

[skywagon8a]

There's some reasons fixed skis are rigged with a rear limit cable. In my experience once they reach their up limit it tends to lift the plane and prop out of deep snow and frozen crust - a potential benefit for takeoff. If rigged too nose up the skis tend to rise and plow through deep snow, not lift the plane enough, and cause drag that slows takeoff.

Gary

Good point, the pivot point moves forward to the tip of the ski forcing the aft end up.

 

[BC12D-4-85]

There's a ski angle balance that can be tested and adjusted if interested. It varies by ski and aircraft model plus snow conditions. AC 43.13-2B Ch. 5 (http://content.aviation-safety-bureau.com/allmembers/ac-43-13-2b/sections/ski-installations.php) suggests +-0 to +-5* nose up from level attitude.

I like them rigged so that adding an optional second bolt-on rear ski tab (~+1.25") gives the ~5* max...without the extra tab they're flatter. That lets me tune the angle for some faster cruise or better performance and less strain as snow conditions change like from early winter deep powder to late rough wind blown bumps. It take some experience to find the best setup.

Gary

 

[mvivion]

I dunno, I think it’s quite possible to overthink this stuff. Folks been rigging these things for decades, using basic instructions and frankly, as rough as ski flying can be on Airframes, it’s kinda surprising there isn’t more damage done.

I like skis rigged one degree nose up relative to the bottom of the wing.

I don’t know how you’d get aft limit cables rigged with springs without using two cables, like forward rigging. That’d be draggy, and would likely cause an FAA type to have a coronary.

And it takes some pretty ugly snow conditions, and talent to bend stuff back there while taxiing anyway.

Finally, like it or not, it’s best to rig every ski installation to the airplane it’s going on. Yeah, they’re all kinda alike, but....

MTV

 

[BC12D-4-85]

Mike has a good point in that history has proven a basic starting point. But skis built flatter than others and also rigged flat can submarine and drag. Northland and Landes come to mind. Skis built in a rocker style like Federal and Aero with an upturned tip and tail behave differently and should be rigged accordingly. Testing will confirm the best setup.

Interlacing a rear spring with a single cable involves nicopressing thimble attachments to each end of the spring with a slack cable loop in between. Not the best but I've seen it done.

During the 17 years I airplane trapped I routinely replaced the rear cables on Landes 2500 and Aero 3000 every two years. Thimbles flattened to the point they couldn't be rotated around the ski tab hole were a clue. Work'em and stretch'em.

Then there's single beam wheel skis rigged nose up that climb too quick out of powder and leave the skinny azz mid and tail portion to support the plane. Been there for a few thousand.

Last thought: Power on skis is king and can mask a non-optimum setup. Try 65-100 hp or altitude in deep snow and the rigging becomes a factor.

Gary

 

[mvivion]

Indeed, relatively “flat” skis, with little rocker or upturn in front aren’t my favorite.

MTV

 

[stewartb]

Airplane skis are rigged relative to level flight. I don't reach that attitude on the ground so there's normally slack in the rear cables for ground ops, and I've never experienced any nose diving tendencies. I prefer skis rigged nearly flat so they don't fly tips up. I have no doubt that I've reached aft check cable limits in drifts but it appears the additional force transfers to the aircraft suspension, and I've tested that a few times. Ski rigging gets more preflight attention than anything on my planes. So far so good.

Air Glide skis have an internal bungee to the aft check cable. I assume it accommodates the ski travel between deployed and retracted. FliLites travel less and use a straight check cable like straight skis. For what that's worth.

 

[cubdriver2]

I'm the 3rd one around here now one Summit skis. We all have had the same problem at first. If you rig them fairly flat the tips will drop in flight after you go over about 100mph, like in a diving turn. When I got these I thought the tips were rigged to high so I shortened the rear cables 1.25" , when flying with Jeff last Thursday I had him take a picture so I could see what they looked like in flight. Seemed fine, about 2 minutes later both dropped the tips during a decending turn. Slowed to about 65- 70 mph and they came back up. I think the springs are plenty strong but because there is so much more ski area out front to grab air that they are rigged to flat. We all have added a chain repair link to rear cables and with the tip another 3" higher they now stay up



Glenn

 

[mam90]

I'm the 3rd one around here now one Summit skis. We all have had the same problem at first. If you rig them fairly flat the tips will drop in flight after you go over about 100mph, like in a diving turn. When I got these I thought the tips were rigged to high so I shortened the rear cables 1.25" , when flying with Jeff last Thursday I had him take a picture so I could see what they looked like in flight. Seemed fine, about 2 minutes later both dropped the tips during a decending turn. Slowed to about 65- 70 mph and they came back up. I think the springs are plenty strong but because there is so much more ski area out front to grab air that they are rigged to flat. We all have added a chain repair link to rear cables and with the tip another 3" higher they now stay up



Glenn

Thought my rear cables were a little long, but have been too lazy to make new ones. Think I’ll leave them alone. Never had the tips drop and don’t see any noticeable speed change with the skis on....

 

[cubdriver2]

Mark, this is all your fault. There are at least 6 sets of Summit skis around here because we met you at Crow Island 3 years ago. I hope that Mike at Summit at least sends you a Christmas card?



Glenn

 

[mam90]

Glad I could help the economy out!

 

[BC12D-4-85]

This last week a local C-170 pilot on AWB 2500 wheel skis (not sure of the exact model and rigging configuration) reportedly had a quick look at the ground. He recovered, later declared an emergency and had a safe landing. Now there's more of the story to unfold. They can tend to point negative to the aircraft level in wheels down mode from what I've read so far. I've no experience with them.

Be careful out there.

Gary

 

[TurboBeaver]

Here is a great pic of skis rigged way tip high ( stolen from
Glens album) This was the norm around here 40 years ago, about every set looked like this and we were all wondering why we were only going 80mph! To each his own.

 

[BC12D-4-85]

Consider the effect of floats (with upturned nose) or huge tires vs relatively streamlined skis on cruise. Their effect may not be that bad especially on Cubs flying in the world of 80's.

Gary

 

[cubdriver2]

Here is a great pic of skis rigged way tip high ( stolen from
Glens album) This was the norm around here 40 years ago, about every set looked like this and we were all wondering why we were only going 80mph! To each his own.View attachment 40444

That's my friend Frank, I offered a bunch of times to make him new rear cables. He said they looked fine when he looked out the window.

Glenn

 

[mvivion]

This last week a local C-170 pilot on AWB 2500 wheel skis (not sure of the exact model and rigging configuration) reportedly had a quick look at the ground. He recovered, later declared an emergency and had a safe landing. Now there's more of the story to unfold. They can tend to point negative to the aircraft level in wheels down mode from what I've read so far. I've no experience with them.

Be careful out there.

Gary

Gary,

thats interesting. I had AWB 2500s on my 170, and I’m trying to imagine how they could go nose down very far with those riggers installed, unless a rigger broke. Keep us posted with more info when you get it.

MTV