Don,
Thank you for that fascinating lecture. I have seldom felt so ignorant
since I joint the KRNet!
Moreover, you just gave me something to brag about when I will meet the
airworthiness inspector! ;-)
Serge
Donald Reid <donr...@peoplepc.com>
Envoyé par : krnet-boun...@mylist.net
2005-05-11 19:24
Veuillez répondre à KRnet
Remis le : 2005-05-11 20:57
Pour : KRnet <kr...@mylist.net>
cc : (ccc : Serge VIDAL/DNSA/SAGEM)
Objet : Re: KR> Empty weight
At 10:26 AM 5/11/2005, you wrote:
>I noticed that my WAFs'lightenigh holes are all 1/2" diameter, so I
>probably can increase these holes as per specs. Every little helps.
Please note that these holes are not to make the fitting lighter, but a
part of the structural design of the fitting. The graduated size is
important.
Quoting from ANC-18, Design of Wood Aircraft Structures
"BEHAVIOR OF DISSIMILAR MATERIALS WORKING TOGETHER When materials of
different rigidities such as wood or metal fittings are fastened together
... and are under high stress ... (such as) a long metal strap bolted to a
wood spar flange for the purpose of taking the load out of the wood at a
wing joint. In order that the load be uniformly distributed among the
bolts, the ratio of the stress to the modulus of elasticity should be the
same for both materials at every point. This may be approximated in
practical structures by tapering the straps and the wood in such a manner
that the average stress in each divided by its modulus of elasticity gives
the same ratio."
This is a fancy engineering way of saying that the material in the metal
fitting must be tapered as it progresses away from the removable
bolt. That is the point where the load is applied to each fitting.
It is more difficult to taper the material in thickness than it is to
taper
it in equivalent width. That is why the holes increase in size from the
outside to the inside. The material that is left then decreases toward
the unloaded end of the fitting. The holes should be sized as called in
the plans to make the correct fitting.
Don Reid - donreid "at" peoplepc.com
Bumpass, Va
Visit my web sites at:
AeroFoil, a 2-D Airfoil Design And Analysis Computer Program:
http://aerofoilengineering.com
KR2XL construction: http://aerofoilengineering.com/KR/KR2XL.htm
Aviation Surplus: http://aerofoilengineering.com/PartsListing/Airparts.htm
EAA Chapter 231: http://eaa231.org
Ultralights: http://usua250.org
VA EAA State Fly-in: http://vaeaa.org
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