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Thread: Snow Load on wings

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    Member RocketRick's Avatar
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    Question Snow Load on wings

    Whelp the plane is tied down outside..

    The plane is a 180B.

    How much snow load, ie depth, should I allow before I remove it?

    Also, is a cowling and /or cabin cover helpful/necessary. I red the covers come loose in the wind and can damage the skin.

    Thanks

    Rick

  2. #2

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    6 to 8" is where i brush my wings on the cub. Wet heavy snow can weigh alot. the rear strut on the cub is it's weak spot so a tail wind and wet snow can bend the strut. Not sure how 180's wings fair.

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    If I'm parking it for the winter or even a couple of months of winter I don't use covers. Covers will damage paint and plexiglass in even mild winds. No need to cover an inactve plane. I still sweep off the snow once it builds up to more than a couple of inches. If there's a big storm I wouldn't worry about 6-8-10" being on the wings for a day or so. If you do that you should have external control locks on so the weight isn't pulling on your cables and pulleys. If I'm keeping the plane active I use engine, wing, tail, and windshield covers. The sweeping follows the same rules. Covers come off when the winds get past the mid 20 mph range. I've had them on in higher winds but there's no good reason not to strip them when it's blowing.

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    Member Float Pilot's Avatar
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    Make sure you have a soft broom. A couple of my boys used a big push broom with some sort of hard wire or plastic bristles mixed in... It caused all sorts of damage. Plus never let a teenager use the hard part of a broom to smack ice off the wings..
    Floatplane,Tailwheel and Firearms Instructor- Dragonfly Aero
    Experimental Hand-Loader, NRA Life Member
    http://site.dragonflyaero.com

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    Thanks guys I'll follow those tips.

    I made & installed a rudder lock already and plan to make some for the elevators and aileron/flap interface.

    I talked and flew with a guy that's had a 180 up here since the early 80's and he said no prob as long as its tied down well.

    His rec for the preservation oil was to just use 1-quart and fly for an hour and call it good. Other folk say use all p-oil. He said he didn't use any at all for years and got over TBO on his 0470s.

    Thanks

    Rick

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    I'll put one to bed for the winter tomorrow. It'll get 11 qts of Phillips anti-rust oil and 1 1/2 pints of Camguard. Then I'll fly it for the prescribed half hour and park it 'til spring. Rust will kill my engine way faster than I can wear it out. Preservative oils are the best thing I can do to put up a good fight.

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    Default P-Oil

    Quote Originally Posted by Mr. Pid View Post
    I'll put one to bed for the winter tomorrow. It'll get 11 qts of Phillips anti-rust oil and 1 1/2 pints of Camguard. Then I'll fly it for the prescribed half hour and park it 'til spring. Rust will kill my engine way faster than I can wear it out. Preservative oils are the best thing I can do to put up a good fight.
    PID,

    Some say to drain the p-oil after that last flight & don't move the cylinders till next season. Some say to leave the p-oil it in all winter.

    What say you?

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    I say read the instructions from TCM and from the oil manufacturers. If you're going to deviate from those procedures, decide for yourself what's important and what isn't.

    http://www.tcmlink.com/pdf2/SIL99-1.pdf

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    Quote Originally Posted by RocketRick View Post
    Whelp the plane is tied down outside..

    The plane is a 180B.

    How much snow load, ie depth, should I allow before I remove it?

    Also, is a cowling and /or cabin cover helpful/necessary. I red the covers come loose in the wind and can damage the skin.

    Thanks

    Rick
    One-foot of wet snow is equal to about one-inch of water. Fresh water weighs 32.4 lbs/square ft. Your C-180 has about 740-square ft of area (I think - - - better check that!). This means the wing is holding perhaps 24,000 pounds in negative load. Do what you think best . . . . .

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    Yep depends on the Snow! brush it off everytime it snows. If your not flying, (like someone else said) you don't need covers.
    Tim

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    Quote Originally Posted by Grizzly 1 View Post
    One-foot of wet snow is equal to about one-inch of water. Fresh water weighs 32.4 lbs/square ft. Your C-180 has about 740-square ft of area (I think - - - better check that!). This means the wing is holding perhaps 24,000 pounds in negative load. Do what you think best . . . . .
    Yeah Griz I was thinking of doing that calc myself for wing loading per specs. I did road and drainage and hydraulic design as my vocation.

    Always good to get the advice from the experienced hands that have been there and done that. Like I heard one guy say.. "You don't know what you don't know" HA!.

    That's why I'm on this forum.

    Thanks for that link PID.

    Rick

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    24,000 pounds???? 1 foot of wet snow on a 180??? Check your math

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    Quote Originally Posted by Gambler 17 View Post
    24,000 pounds???? 1 foot of wet snow on a 180??? Check your math
    I'll do it later and post the value. No probs mate.

    RR

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    @ - wing area, - 174 ft2
    - ailerons - 18.2
    - rudder -17.29
    - tailplane 20.96
    - elevators 15.2

    I cant find 700 + square feet ??/

    thats of course a 180 SW

    If you cant stand behind the troops in Iraq.. Feel free to stand in front of them.

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    It's okay. I think Grizzly1's 24,000 pounds is based on 1 foot of water on your wing not wet snow. The weight should be in the neighborhood of 2000 pounds if the 180 has 740 square feet wing.

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    Talking Snow load on plane wings.

    Whelp the values used for roof design in ANC is LL = 50 PSF + DL = 10 PSF = 60 PSF. But they add a 10 PSF unbalanced snow load of 10 PSF. Lets lgnore that. ( I just had some small trusses delivered & thats the values they used) So Total load is 60 PSF.

    Remember that's letting the snow build up over the winters and not removing it. Like it got 4'+ in the 80's on my roof in ANC. No damage. Point is these are conservative load values.

    Area of wings are 174 SF + 4SF for stol kit = 178 SF.

    Loading = 178 SF X 60 PSF = 10, 680 lbs downward load. Or,....abt 5,340 lbs for each wing.

    When you throw in load factors and the fact that the plane is designed for 150% of those load factors, I figure remove the snow asap after each snow and def it if gets over 6-8".

    Anyways, I got a girl Friday that will do it..No probs mate.. HA!.

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    Just remember that a snow load puts a compression force on the struts so you must use the NEGATIVE G load factor limit in your calculations.
    Louis Knapp

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    I did some research her is a good rule:
    A guideline is that light aircraft wings are stressed downward for a "minus 2 Gs" - twice the aircraft's static weight. Most owners realize that when it snows, they had better relieve the snow weight off the wings. Consider that the average light aircraft has 150 square feet of wing area and a total aircraft weight of 2000 lbs. This would yield 26.67 lbs. per sq. foot or a water equivalent of 5.1 inches as a very rough guideline for wing damage due to snow accumulation.

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    Gambler & Louis,

    I looked that up prior to my last post. My owners manual says Load factor is -1.5 x a gross weight of 2650 lbs. Mine is about 2670-lbs.

    So -1.5 x 2670 = -4,005 lbs.

    Th owners manual also say the design load factors are 150% of those given values. Hence forth and whither to, that yields;

    -4,005-lbs x 1.5 = -6,007-lbs neg load, ie down on the wing.

    Point being is even if you let the snow build up all winter and never remove it, you most likely won't damage the plane.

    Most materials are much better at compression then tensile. I believe the struts follow that rule. Hence the weak link is prob the bolts and connections of the struts to the fuselage and wing. IE,...the connections will break before the struts go into failure.

    Quiz: What is the strongest material known per unit weight?

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    Quote Originally Posted by RocketRick View Post
    Gambler & Louis,

    I looked that up prior to my last post. My owners manual says Load factor is -1.5 x a gross weight of 2650 lbs. Mine is about 2670-lbs.

    So -1.5 x 2670 = -4,005 lbs.

    Th owners manual also say the design load factors are 150% of those given values. Hence forth and whither to, that yields;

    -4,005-lbs x 1.5 = -6,007-lbs neg load, ie down on the wing.

    Point being is even if you let the snow build up all winter and never remove it, you most likely won't damage the plane.

    Most materials are much better at compression then tensile. I believe the struts follow that rule. Hence the weak link is prob the bolts and connections of the struts to the fuselage and wing. IE,...the connections will break before the struts go into failure.

    Quiz: What is the strongest material known per unit weight?
    I messed up in that the allowable load on each wing is 1/2 the above calc. Hence each wing shld take ard 3,000-lb downward load before failure.

    Make sense?

    RR

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