. Automotive industries . ll as speeds relative to the ground or air. Care is takento experiment in calm weather although a wind vane givesthe component of the relative wind which is taken into ac-count in the calculations. An electric current scores a reference mark at the rightmoment on the record of each instrument and thus facili-tates taking all the measurements simultaneously. Com-parative wing tests between the truck and the large windtunnel show that the two methods are in substantial agree-ment. The truck for propeller testing (Fig. 4) differs from thetruck just described in that it i
. Automotive industries . ll as speeds relative to the ground or air. Care is takento experiment in calm weather although a wind vane givesthe component of the relative wind which is taken into ac-count in the calculations. An electric current scores a reference mark at the rightmoment on the record of each instrument and thus facili-tates taking all the measurements simultaneously. Com-parative wing tests between the truck and the large windtunnel show that the two methods are in substantial agree-ment. The truck for propeller testing (Fig. 4) differs from thetruck just described in that it is driven by the propellorunder test. An 80 motor drives the propeller throughtwo bevel gears at speeds between 0 and 50 miles per hour. The vertical shaft connected to the universal joint be-tween the two transmission cases can be displaced paral-lel to its axis. The shaft is partially held in place for-ward by a ball thrust bearing at the top of the framejointed at the base. The shaft is supported by a Aerodynamic teHtiny equipment mmed by the Aeronautic Institute Laboratory at St. Cyr, France April 21, 1921 AUTOMOTIVE INDUSTRIESTHE AUTOMOBILE 855 Under the action of the pull of the propeller the hori-zontal shaft tends to move forward, taking with it the topof the frame. This movement is checked and recorded bydynamometers. The forward speed is, measured by meansof a tachometer giving the speed of rotation of the backaxle and it is checked by an anemometer giving directlythe speed of the truck with reference to the air. Thespeed of revolution of the propeller is read on a tachome-ter giving the revolutions per minute of the motor. Wattmeters indicate the power delivered and absorbed by thescrew. From the information furnished by the various record-ing instruments which includes the traction of the pro-peller, revolutions per minute, absolute ground speed, rela-tive speed with respect to the air, power delivered andabsorbed, the efficiency curves of each ty
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectaeronautics, bookyear
