Placement of the strain gages on the webs of the front and rear spars and the electrical interconnection therecf are shown in Pig, 2.2, The resulting circuit is a four-activeearm Wheatstone cridge very similar to that employed for the torsion gage. The installation used for measuring shear in a single spar is shown in Fig. 2.3. 2.3.2.4 Acceleration The Statham, Type A-18, accelerometer was used for all acceleration measurements. Accelerometers covering the range of +6 g and =12 g and having 4 nominal tridge resistance of 350 ohms were selected, These transducers are accurate to 1 per cent of full scale with a re- gponse to transverse acceleration of not more than 2 per cent. Darping, 3.5 to 0.7 of critical, «as provided by a special silicone fluid. Tem perature of the unit was maintained constant by means of an internal, thermostatically controlled, heater unit. 2.3.3 Response Sign Convention For convenience in indicating the direction of response, an arbirary sign convention had teen adopted for use in this report. in the definitions below, a ncrmzl flight configuration is assumed, The Fositive direction for the various responses is defined as follows: a, b. c. 2.3.4 Acceleration, hormal - an increase in the upward velocity or decrease in the downward velocity of the aircraft or any component thereof. bending (Aft Fuselage) - tail deflection upward, compression in upper surface, vending (Wings and Stabilizers) ~ tip deflection upward, d. compression in the upper surface. Overpressure - the differertial pressure above azcient pres- e. Shear (Wing and Ctabilizers) - tip deflection upward; same f. Torsion (Wing) - leading edge of wing deflected upxard with sure, sign as positive cerding. respect to remainder of wing. Recording Equipment The major portion of the data was recorded by means of a standard recording oscillopreph. ‘where very fast response was required, a codified ozcilloscore with a recordinrs camera was emrloyed. The princi:le of operation ani salient features of the recorders and associate eculnmert are : vawe ~- on re - feet ree ve tte +* ‘° re Ie aircraft. | t. gages and was likewise located in the left outer wing panel of the 3~36 eee te As with the torsion gage, the shear gage employed 16 strain : .. ‘s sion and measure total shear on the component directly, and the indirect individual structural members was measured, method, wherein the shear The output of the latter age was not used directly but was combined with the cutput of other gages in accordance with an empirically determined formila to yield a value for total shear. Paial ment which employed a shear gage designed to cancel the effects of tor- * . * re ’ a “ " Fat atal et - oN . - ee be eli mm Ba a Bt ee ee ee RE te ta nee a oe AOne ee RO A Re a HB ee