Different wings

61 posts in this topic

Posted

Dimi3 - yes, those wings were off my Aerotrek. I bought new wings from the factory to comply with their SLSA repair manual but thinking I may repair the old ones and sell or use them on my A+ someday.

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Posted

Sorry, but dholly is incorrect.  Camber refers to curvature of the airfoil's meanline, midway between upper and lower surfaces.  Undercamber is concavity on the lower surface.  

Back in my hang glider days we used the 0.058"wall thickness a lot since the tubing sizes step in 1/8" increments, and the next size tubing up or down could be used as external or internal doublers.  The 0.065 wall thickness doesn't quite work. My homemade Rogallo had 2024 t-3 doublers!   A great way to make a wing both strong and light is to step the tubing according to bending stresses, and make the rear spar more flexible than the front so under high loading the wing washes out, driving the airloads inboard.  On the Avids the little wood reinforcement inside the spars at the attach point is for crush/crimp prevention - very smart!

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Posted

Sorry, but dholly is incorrect.  Camber refers to curvature of the airfoil's meanline, midway between upper and lower surfaces.  Undercamber is concavity on the lower surface.  

Welcome to the forum Turbo. To be clear, I was not referring either to mean camber (your definition above) or the amount of camber (the difference between the mean camber and chord line). Every airfoil also has a distinct upper surface and lower surface camber and I was simply referring to the lower surface camber.

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Posted

Hello everybody,

 

The reason for starting this topic is that I just purchased Avid Flyer MkIV. It is supposed to be with Heavy Hauler wing but

the seller said it to have Heavy Hauler's wing length and speedwing wing profile.

 

Does anybody have any idea where to get e.g. speedwing profile to make comparation since papers that came with the plane don't have such drawings? Suggestions?

 

Cheers,

Kekkuli

 

 

The speed wing does not have the undercamber in the wing. If they built it to HH specs (more ribs and heavier spars) then you really have the best of both worlds. The full length speed wing will fly almost as slow as my HH wing. I could get my buddies MK IV with the extended speed wing in and out just as short as my C HH.

Wing contruction.pdf

Leni, I have a set of Aerobatic wings. At first, I though of extending them, but the washout is rung out at the tips already. I am considering building another Aerobatic wing set, but with full length spars and with around 1.5 inched of washout instead of the 2 inches. What are your thoughts?

I wouldn't build a set with more than a half inch, maybe 3/4 at the most.

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Posted

Wow this thread has had over 9 million views.  Must be something going on there,!

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Posted

Probably cause everyone wanted to hear what Leni had to say....  :lmao:  Sorry Leni, I couldn't resist.  Where have you been Leni?  Sometimes I feel like I've taken Ed's spot in making a lot of comments.  I'm on facebook now, but I don't think that is near as good a venue for transferring information.  Wish those guys would come back here and join the discussion.   JImChuk

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Posted

Welcome Kekkuli,

 

I built a custom hybrid 'long heavy hauler speedwing' for my Avid+, hoping to have the best of both worlds. I used and followed the Mk-IV Heavy Hauler material and construction method (see both Leni's .pdf drawings and the wing difference explanation below), however, I substituted the flat-bottom Speedwing ribs instead of the under-cambered Heavy Hauler/STOL ribs. The root rib on Avid Speedwing/Aerobat planes is a special 'transitional' rib that matches up to the butt rib (which was always HH/STOL shaped to allow folding wing clearance). In the attached pictures, you can clearly see the differences between the speed and under-cambered rib profiles both on and off my wing.

 

Also keep in mind, 'Heavy Hauler' was the name attached to several Avid models. A Heavy Hauler B or C model was 1050lbs M.T.O.W. A Heavy Hauler MkIV was originally 1150lbs and then, to compete with the Kitfox 1200, "re-marketed" as 1200lbs. This is the reason one has to be careful around Avid gross weights and wings. In addition to wing length, material and construction differences, the under-cambered HH rib profile was very different from the flat-bottomed Speed rib profile.

 

In general, Avid Flyer wing differences extend to spar thickness, spar length, lift strut o.d. diameter, airfoil, rib spacing and drag tubes. All wings called for (2) nose ribs between wing ribs, though an additional nose rib per bay is often added on the Speed and STOL wings due to their wider rib spacing. Here are the basic differences between the (4) Avid Flyer wings explained:

 

 

 

Speedwing
: .065" thick 2-1/2" o.d. spars; 108-1/2" spar length; 3/4" dia. lift struts; Avid flat bottom airfoil; (7) ribs ~ 18" o.c.; (3) 1/2" dia. W-2 alum drag tubes; (3) W-3S Short 5/16" dia. alum root rib brace tubes; (1) W-4 Short 1/2" dia. alum root rib brace tube; (1) W-3L Long 5/16" dia. alum tip rib brace tube*; NOTE: Wing tank replaces (1) W-2, (3) W-3S and (1) W-4 alum rib brace tubes at the root end of wing; Key rib dimensions (long rib flaperon hinge) are 35-1/2", 71" and 106-1/2" o.c. from tip rib

 

 

 

 
Mk-IV HH
: .083" thick 2-1/2" o.d. spars; 144" spar length; 7/8" dia. lift struts; Avid undercamber airfoil; (13) ribs ~ 12" o.c.; (1) 1/2" dia. W-2A steel drag tube; (3) 1/2" dia. W-2 alum drag tubes; (3) W-3S Short 5/16" dia. alum root rib brace tubes; (1) W-4 Short 1/2" dia. alum root rib brace tube; (1) W-3L Long 5/16" dia. alum tip rib brace tube*; NOTE: Wing tank replaces (1) W-2A, (3) W-3S and (1) W-4 alum rib brace tubes at the root end of wing; Key rib dimensions (long rib flaperon hinge) are 35-1/2", 71", 106-1/2" and 142" o.c. from tip rib

 

 

 

 
STOL
: .065" thick 2-1/2" o.d. spars; 144" spar length; 3/4" dia. lift struts; Avid undercamber airfoil; (9) ribs ~ 18" o.c.; (4) 1/2" dia. W-2 alum drag tubes; (3) W-3S Short 5/16" dia. alum root rib brace tubes; (1) W-4 Short 1/2" dia. alum root rib brace tube; (1) W-3L Long 5/16" dia. alum tip rib brace tube*; NOTE: Wing tank replaces (1) W-2, (3) W-3S and (1) W-4 alum rib brace tubes at the root end of wing; Key rib dimensions (long rib flaperon hinge) are 35-1/2", 71", 106-1/2" and 142" o.c. from tip rib

 

 

 

 
Mk-IV Aerobat
: .083" thick 2-1/2" o.d. spars; 108-1/2" spar length; 7/8" dia. lift struts; Avid flat bottom airfoil; (10) ribs ~ 12" o.c.; (1) 1/2" dia. W-2A steel drag tube; (2) 1/2" dia. W-2 alum drag tubes; (3) W-3S Short 5/16" dia. alum root rib brace tubes; (1) W-4 Short 1/2" dia. alum root rib brace tube; (1) W-3L Long 5/16" dia. alum tip rib brace tube*; NOTE: Wing tank replaces (1) W-2A, (3) W-3S and (1) W-4 alum rib brace tubes at the root end of wing; Key rib dimensions (long rib flaperon hinge) are 35-1/2", 71", and 106-1/2" o.c. from tip rib

 

 

 

* Applies to wings with wire trailing edge only, not required with metal trailing edge.

 

 

 

 

Be aware that wings with the exact same descriptors, ie., STOL wings, may have different Gross ratings depending on when they were sold/built. One thing is certain, there were so many combination of fuselages and wing components bought, built, or cobbed together over the years it can be very difficult to determine exactly what Gross you have unless you physically measure spar thickness, tubing diameter, or even cut a tube to verify wall thickness.

 

With the s/n#, Airdale Sportplane and Supply may be able to provide an accurate factory build manifest at the time of sale but, beware, changes could have easily been made in the years following that impact the original Gross.

 

Hope that helps. Best of luck with your new Avid, let us know how things are going!

 

-Doug

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HI Doug.

My C-mod STOL has 0.083" spars and 3/4" struts.SN 466. it was built in 1992. Does that mean my MTOW is 1050lbs? Do you know of any documents that can verify this? In my Swedish papers it say MTOW is 911 but I believe that they didn't know that there also was a C HH version.

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Posted

Hi Anders,  I think the 3/4" lift struts are what is limiting your MTOW.  If you could find some 7/8" lift struts, then probably have the higher gross weight.  Like they say, a chain is only as strong as it's weakest link.  JImChuk

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Posted

Hi Anders,  I think the 3/4" lift struts are what is limiting your MTOW.  If you could find some 7/8" lift struts, then probably have the higher gross weight.  Like they say, a chain is only as strong as it's weakest link.  JImChuk

Hi Jim.

Yes but MkIV HH have a gross of 1150lbs-1200lbs and I was hoping that was because of the 7/8" struts and more ribs, different tail feathers, gear and fuselage?

I counted the ribs on mine and there is only 9 ribs, so it seems like it's a standard STOL wing with HH spars?! I am hoping this would result in a MTOW of 1050 instead of 911 or 1150lbs. Bit of course this is only guessing and until I really know, I stick with 911lbs.

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Posted (edited)

Avid loaded up a stol wing to about 5.7 Gs and left it for 15 minutes.  That was far in excess of the 911 gross weight if you figure 3.8 Gs as being ok.  The wing suffered no damage.   So what will you wings take?  Who knows.  Maybe there was a flaw in some weld, or some unseen rust in the lift strut tubes, or maybe they will go beyond the 5.7 Gs load done in Avid's test with no problem.  I think Kitfox did some testing on lift struts, and at 15 Gs the 1/4" bolts started to shear/tear off.  I don't remember all the details of that test, and probably shouldn't mention it, but maybe if you search for it you will find out more info.  Here is a picture of Avid's test.  JImChuk

 

Avid+STOL+load+test.jpg

Edited by 1avidflyer

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Posted

Hi Anders,  I think the 3/4" lift struts are what is limiting your MTOW.  If you could find some 7/8" lift struts, then probably have the higher gross weight.  Like they say, a chain is only as strong as it's weakest link.  JImChuk

Hi Jim.

Yes but MkIV HH have a gross of 1150lbs-1200lbs and I was hoping that was because of the 7/8" struts and more ribs, different tail feathers, gear and fuselage?

I counted the ribs on mine and there is only 9 ribs, so it seems like it's a standard STOL wing with HH spars?! I am hoping this would result in a MTOW of 1050 instead of 911 or 1150lbs. Bit of course this is only guessing and until I really know, I stick with 911lbs.

just put it on floats then all those components magically get stronger ha.

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