I have been in Aerospace Quality Assurance for 22 plus years, so I thank I
Can address this issue.
What is needed is simplicity, inspection (that is quality control) is not
the best way to assure quality - it adds costs and not value to the product.
In addition, it is not 100 percent effective (the Hemel Checkmaster
Coordinate Measuring Machine is not capable of checking the absolute
accuracy of the wing surface to at least 0.0005", the Checkmaster real world
accuracy is about .0015 inch over all three axes when you consider the
Surface Finish Measurements of the wings). What composite wing manufactures
routinely do to determine how closely their products conform to the
specified airfoil is inherently part of the manufacturing process in the
laying-up of the composite wing. The use of a hard mold in the fabrication
process of the wing results in a indirect readiness or measurements of the
wing; that is, transfer and comparison or conforms to the specified airfoil
as a fixed gage. You can always put the wing back in the mold after the
fabrication process and check it with feeler gages but why. As for the mold
(fixed gage) it can be calibrated (verified for accuracy) with a CMM, but
that is a lot of $$. The manufacture can use comparison templets to gauge
the mold for accuracy.
Greg Nikola :)
Valencia, CA USA, AMA 502
-----Original Message-----
From: RJ Steinhaus [mailto:[EMAIL PROTECTED]]
Sent: Friday, August 11, 2000 12:39 PM
To: [EMAIL PROTECTED]
Subject: [RCSE] Measuring Conformance of Composite Wings
I would like to know if there are any manufacturers that routinely do
quality control on their composite wing manufacture to determine how closely
their products conform to the specified airfoil? Dr. Michael Selig made
graphs in Soartech 8 "Airfoils at Low Speeds" of the conformance of the wind
tunnel models used in the generation of his performance information for
studied airfoils. In that study Dr. Selig used a Hemel Checkmaster
Coordinate Measuring Machine. This machine was capable of checking the
absolute accuracy of the wing surface to at least 0.0005" (many of the wind
tunnel models diverged significantly from perfect conformance to the desired
airfoil). Do the molded wing manufacturers "close the loop" doing checks on
accuracy/quality or is everyone just doing "best effort" manufacture? Has
anyone made a simplified airfoil profile measurement tool implemented with
two digitizing travel gauges that can be clamped on an existing wing at
various points to survey wing top and bottom surface airfoil profile
conformance (this measurement may not reveal washout, wing twists or warps,
etc.). The costs of the molded aircraft are relatively high and it would be
nice to have knowledge that the wings of individual models are being
manufactured accurately.
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