A series of drawings depicting various types of aerodynamic control surface balances for airplanes. From top to bottom, they are: a plain flap, an overhanging balance, a beveled trailing edge, a sealed internal balance, a balancing tab, a frise aileron, an external airfoil balance, and a horn balance.
W. Hewitt Phillips
W. Hewitt Phillips, “<a rel="nofollow" class="external text" href="http://history.nasa.gov/monograph12/ch6.htm">Chapter 6: Problems Encountered as a Result of Wartime Developments</a>,” in <i>Journey in Aeronautical Research: A Career at NASA Langley Research Center</i>, Monographs in Aerospace History 12 (Washington, D.C.: NASA History Office, Office of Policy and Plans, NASA Headquarters, 1998), 49.