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Wing Testing

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Posted

Hey, If we could get about 3000 pounds of those sandbags from the East Coast, it would be cheaper than buying that many - and we could pass them around for wing tests!   EDMO

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Posted

Too soon....:lmao:

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Posted

Prepaid freight for sure.

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Posted (edited)

How about some "Sand Bag Fly-ins" where we could each bring a couple of bags "Bag Drop Contests"? and exchange them for a beer or breakfast -  replace Oshkosh?  Maybe cheaper to just buy 100 of the 30 lb bags at $1.40 per bag, but fly-in sounds like more fun!

EDMO

Edited by EDMO

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Posted (edited)

Jim,   Re: Avid wing tests that you posted:  I lost track of the post that I printed out.   It says Avid Flyer - What model Flyer was this?  Were these .065 wall spars with no inserts or with what insert?  Were these the weakest of the Avid wings at 911 GW?   Did GW change between models A, B, C, and was that because of a change in wing inserts, struts, or what?    EDMO

Edited by EDMO

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Posted

I don't know the answer to your questions Ed.  The Avid A model had a gross weight of around 760 lbs. if I remember right.  The B model STOL wing was 911.  I don't know what the B model with heavy hauler wings was supposed to be, but the C model with the HH wings was 1050, and the MK IV with HH wings was 1150.  Don't know what or if any inserts were in wing tested in the picture I posted.  JImChuk

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Posted (edited)

I don't know the answer to your questions Ed.  The Avid A model had a gross weight of around 760 lbs. if I remember right.  The B model STOL wing was 911.  I don't know what the B model with heavy hauler wings was supposed to be, but the C model with the HH wings was 1050, and the MK IV with HH wings was 1150.  Don't know what or if any inserts were in wing tested in the picture I posted.  JImChuk

I didn't know when the HH wings came out or for what models - I thought it was for the Mark IV "4" to compete with Kitfox IV "4".   My Avid education started with the Airdale and the Magnum, except I knew of Dean Wilson and Avid #1 story and thought there were 100 more Kitfoxes flying for every Avid, until I got on here. 

BTW:  Reading some of John Larsen's article:  History of Avids - Paraphrasing,  "Kitfox parts from models 1 - 3 would fit Avids.  One guy needed a wing for his Avid and got one from a Kitfox, and flew just fine with one wing from each"!   The guys who say Kitfox wings won't fit an Avid should read that!  Ha!   EDMO

Edited by EDMO

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Posted

Interesting that the brochure for the earlier STOL models have a Vne of 97 mph, and the sandbag test gives a load factor below yield of 5.9 Gs.  If ias is close to eas, and stall is at 40 mph ias,  guess what?  The Vne is really maneuvering speed!  Yes, Virginia, you can go faster in smooth air!

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Posted

Sandbag static test was performed without spar stiffeners in place, IIRC.

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Posted

Interesting in that those wood pieces are really not stiffeners, but tube crimp preventers.  The curved steel attach plates for the wing struts likely serve the same function anyway.

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Posted

The early kitfoxs and probably avids had small diameter struts and most important, the carry thru tube in the lower fuselage is what the lower lift strut attachs to and one failed in Australia. There is a CAA AD to check this area for cracks.... This is one reason the GW is lower on early models.

The second is the tubular spars are .062" wall thickness and the later models its is .083"  I think or close to that...

Also there is a theory out there that at high speeds with the undercambered wing, the is a downward force on the front lift struts and if you get in turblence, the jury stuts can buckle and then the lift strut buckles and your done.... so Id fly very conservativly with an early model plane.

THe VNe speed was changed a little when you added the flaperon balance weights on to keep from flutter.....

 

F2006B04824 (1).pdf

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Posted

The skyfox (as noted in your attachment) and other knock offs should not be a direct comparison to the Avid or Kitfox.  There were lots of companies popping up to try and grab a piece of the homebuilt pie, and many were not any type of engineers, just guys welding sticks together trying to make a cheaper copy of an existing design.  Think of modern day cheap Chinese knock offs. 

Kitfox still uses the .062" spars on the latest models with higher gross weights.

The wood spar stiffeners are indeed spar stiffeners, however, I guess by definition they are also "anti wrinkle devices".

The VNE change was not just about the counterweights.  The counterweights were after a Boeing engineer did some square rooting and thought that a flutter under certain conditions could develop.

 

:BC:

 

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