Laser Doppler Velocimeter Development

A new two-channel laser Doppler velocimeter developed for the Ames High Reynolds Channel No. II is described. Design features required for the satisfactory operation of the optical system in the channel environment are discussed. Fiber optics are used to transmit the megahertz Doppler signal to the photodetectors located outside the channel pressure vessel, and provision is made to isolate the optical system from pressure and thermal strain effects. Computer-controlled scanning mirrors are used to psoition the laser beams in the channel flow. Techniques used to seed the flow with 0.5-?-diam polystyrene spheres avoiding deposition on the test-section windows and porous boundary-layer removal panels are described. Preliminary results are presented with a discussion of several of the factors affecting accuracy.     

Digital Cartographic Data: A Case for Electronic Delivery

The demand for digital cartographic data and information is expanding rapidly, most dramatically in navigation. Electronic chart and map display systems are now reaching the market for land, sea and air navigation and rapid delivery of the latest data is absolutely essential. Commercial aviation is moving rapidly toward the automated cockpit with the new generation Flight Management Computer System. Marine navigation is experiencing a similar growth in integrated navigation systems and every major automobile manufacturer has plans for digital map navigation systems. The largest, most complete data bases to meet these requirements are Government held and difficult to access, thus most private sector firms re-digitize and agencies maintain near duplicate data. Present inefficiencies, introduced errors, and delays stem from lack of rapid access and delivery of digital data. Use of newly developed satellite data broadcast technology offers a solution.