Wag aero die springs

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

  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

    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

    Leardriver

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

    chiru

    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

    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

    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

    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

    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.
     

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