Wag aero die springs

Discussion in 'Acrosport' started by chiru, May 13, 2018.

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  1. May 13, 2018 #1

    chiru

    chiru

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    Hello,
    I have bought die springs from Wag and was wondering if the maximum compression distance is sufficient. It is a 2” spring, 1” rod, 6” long. According to the specs, it has a resistance of 32.8 lbs per 1/10 inch. Deflection of 1.5” with 490 lbs and maximum deflection of 3”.
    But the length of the holes allowing the travel are only 2” long (see picture). Is this enough ? There is about 0.25” precompression but isn’t there about one inch missing ?

    A6DE3A0E-F9F5-4ED2-ACB0-59D4BA335C44.jpg

    0A359C51-8056-4092-8700-A5AFBC447228.jpg

    F3C41141-F189-46FC-8F8D-92069D63A1AA.jpg
     
  2. May 13, 2018 #2

    Dana

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    There's a thread on the Homebuilt Airplanes forum about my experience using the Wag Aero struts, including numbers and calculations. My plane's a Starduster but it has an Acrosport style gear.
     
  3. May 13, 2018 #3

    Leardriver

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    What holds the lower spring perch on the tube? Welded I assume?
     
  4. May 14, 2018 #4

    chiru

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    Yes, it's welded.

    I received the following information from Wag :

    "the maximum load is 2200 lbs, & the spring is 6- ¼” long but compresses down to 1- ¼” on each side. "
    I guess the load is for both legs together and the compression is 2.5" to solid.
     
  5. May 14, 2018 #5

    Vilhelm

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    Chiru

    If I understand you right, you say that the spring will travel 3 ", but the slot in the tube is only 2" so 1" is missing. I do not think the spring will travel 3 "

    I made my own shock struts with springs from Aircraft Spruce ( Spruce does not sell complete struts as Wag Aero does ). Now my springs look very much the same as the Wag ones. They are 6 inch long and have 12 coils made from 3/8 inch wire. As the end coils are flattened lets say 11 coils. 11 X 3/8= 4 1/8" so when the spring is fully compressed it is 4 1/8" long. That means a travel on 6" minus 4 1/8 = 1 7/8" so with 1/4" preload a slot 2" long will be fine. The slot ought to be a little longer than the complete travel of the spring.
     
    Last edited: May 14, 2018
  6. May 14, 2018 #6

    smizo

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    I also made my own. if you put the wheels flat with a straight tube in place of the struts, the drawings say to make the length .5" shorter to account for the weight of the plane and they will squeeze out a bit. make it more like 1". I made mine .5 and its a good thing its light. fully loaded at 1350 lbs the wheels are perfectly straight. if it went to full gross of the acro 2 they would tip out a bit I bet.
     
  7. May 14, 2018 #7

    Dana

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    From my spring struts, as measured:

    The spring is 6" long as installed, the actual free length is about 6 1/8. The slot in the tube is 1.75" long. Using a hydraulic press and load cell at work, I measured the spring rate at roughly 200# per 1/8" travel, so the spring rate is 1600#/in and the preload is 200#.

    The closest spring I can match it to is an Associated Spring 106-824 which is 6" long, 4.5" solid, 1473#/inch.

    With these struts and my landing gear geometry, I have 2.6" wheel travel. The behavior was nice at my plane's 1086# gross.
     
  8. May 15, 2018 #8

    chiru

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    Thank you all
     
  9. May 15, 2018 #9

    smizo

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    Chiru, lets see some pictures of your current progress!
     
  10. May 16, 2018 #10

    chiru

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    Sure Chris,

    I created a web album where I store all pictures. It’s quite updated.
    http://acrosport.chiru.ch/

    Let me know if you have trouble viewing it.
     
  11. May 31, 2018 #11

    chiru

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    Maybe I should start a build thread
     
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  12. May 31, 2018 #12

    ernstfokker

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    Yes, please. :)

    -EF
     
  13. May 31, 2018 #13

    smizo

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    go for it!!!
     
  14. Jun 3, 2018 #14

    gha111

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    I put the Wag Aero die springs on my Acro Sport 1 a few years ago. While changing tires a few months ago, I noticed (for some reason) that I was getting NO action on the springs. Hung the plane from the motor mounts and took off the die springs. Found that the outer tube and the inner tube were totally corroded/rusted together. They had to be pounded apart. I had been landing stiff legged for ??? The tolerances between the 2 tubes was net, net, so any amount of moisture like water splash off the runway was enough to lock the spring action up tight with rust. I called Wag and asked them what they had lubed the 2 tubes with. The answer was "Nothing. We put them together dry." Cleaned all the corrosion and lubed the 2 sections with heavy grease. Now on my walk around, I move both wingtips up and down a few inches while looking at the springs to insure I have spring action.
     
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