Position of dragwires in wing bays

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David Teahay

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Aug 22, 2018
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46
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guloid plain,Mars
Hello there����,pls take a good look at the small dots on the bays of this two-spar wing
https://scontent.flos2-1.fna.fbcdn.net/v/t1.0-9/fr/cp0/e15/q65/51665005_787232984985580_2911007715151052800_o.jpg?_nc_cat=102&efg=eyJpIjoidCJ9&_nc_eui2=AeEngFsUkF7L3MNnQRnWFkka3WtxSD9ueMVRn853VKnNrbqj1ur1Sj8Sm8fa0B_ahNxi4oDO8_IBZvLDDiP7AwAOnOEM73e9xsuS50QtNqmu4R-84ZSn942QtgpXT2cMTqY&_nc_ht=scontent.flos2-1.fna&oh=f2fcf1fb566718b723f21987a6c5edaf&oe=5CB6A576
my question is, is the drag and anti drag wire as seen in bay 1 supposed to connect to the root of the compression tube or to the intersection between the wing spars and compression tube as seen in bay 2 or,is the drag and anti drag wire supposed to connect to the wing spars as seen in bay 3.
This is the point I'm at in my project,your answer will be much appreciated.
Inorder words,which bay is set up correctly?1,2 or 3?
 
Last edited:

Chilton

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Jun 28, 2014
Messages
180
Location
Jersey, channel islands
All the ones I have seen the compression strut has a fitting on the end which has the drag wire attachments on it, in terms of your drawing the closest would be bay 2.
 

TFF

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Apr 28, 2010
Messages
15,404
Location
Memphis, TN
Because the drawings are not that detailed, you can't really make a judgment. It's mor of drawn instructions than plans without more info.
 

VP1

Todd C.
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Oct 12, 2009
Messages
253
Location
San Diego, CA
1.Putting nonaxial loads on a compression member is generally not the best option.

2. A good option- wires can attach to compression strut attach point. Simple/light.

3. Would work, but #2 seems simpler to me
 

DaleB

Member
Joined
Jan 22, 2019
Messages
15
Location
Omaha, NE
As noted by others, #1 is not good as it will put bending loads on a compression member. #3 will put additional bending loads on the spars.

If you really want to know which is best, build a small model. Doesn't need to be to scale. Build three identical structures with the same materials, attach wires and see how well each does when you apply a load at diagonally opposite corners. My guess is that the results would be very instructive. But I'm no engineer, I really know nothing about it.
 

PTAirco

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Sep 20, 2003
Messages
3,648
Location
Corona CA
In a Citabria there is no compression strut at the root at all! To pull the wings or reattach them, I attach a temporary strut and tension the wires correctly, hang the wing and then pull the strut out. Cheap but annoying.
 

deskpilot

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Joined
Jun 30, 2009
Messages
1,131
Location
Morphett Vale, South Australia. Just south of Adel
Here's how it's done on my Thruster. Inboard bay has only a diagonal compression tube. The hanging wire goes down to the strut mounts (I think). Second bay has 2 diagonal wires mounted as per image. The 3rd bay has nothing. All bays are of the same size.

DSCF5672.jpg DSCF5671.jpg

Now, I'm thinking that my plane might need a more powerful engine due to modifications making her heavy. Something like a Hirth 582 in place of the Rotax 503. In view of this, speeds might go up and beyond the design limit of the wing so will I need more compression tubes? Any advice gratefully received. Mods, make this a separate thread if you deem so.
 
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