Page 7 - Combined_134_OCR
P. 7

FLYING CARS





                                                                  J79-3                          Afterburner
                                                     i- u u. Turbo- jet engine
                        Cockpit pressurization       Fire bottle   1   *                            Camera
                                                   C02 extinguisher   \
                              duct
                  Multi-channel
                    balancer       Boundary layer
                                      bleed

                                                                                                     \
                                                                                               Drag chute
                                                                                                 housing
                                                                              Fuel tank
                                                                           Main battery
                                                                                      High pressure brake tank

                                                             biggest problem is not so much a reduction in drag
                                                              but “its the lift which will kill you at these speeds.”
                                                               Plans now call for another assault on the sound
                 Air breathing   Instrumentation
                                                              barrier at Bonneville but as yet he has no fixed timetable.
                   system      power
                                                              With proper testing and good area rule work he can
                                                              pick up another 100-150 mph with the same 15,000-lb-
                                                              thrust J79 power plant. The vehicle is to be a com­
                                                              promise between his first Spirit (407.45 mph in 1963),
                Trapped air pressure buckled body panels like card­  and Sonic I.
               board, caving in the skin. To alleviate the problem,   “A healthy set of brakes may be all we need,” he
               panels were punched with louvers, the front fins were   says. But when he goes for the 700 mph barrier he’ll
               doubled in size and a spoiler was added to keep the nose   put his trust in the Goodyear Hemis-Flo drag chute.
               down. Says Breedlove: “The problem is to avoid a flat   (Sonic I had single-disc, 18-in.-diam double-caliper
               bottom, get higher off the ground, and distribute ground   brakes, of %-in. forged steel.)
               pressure more equally to eliminate the tunneling effect   He is thinking of employing an explosive mechanism
               underneath.”                                   with two time delays and a cutting blade in the reefing
                No positive lift was experienced up to 354 mph, but   line. This would chop the line when chute goes out to
               a positive pitching moment on rear wheels was noticed,   4-ft-diam at 700 mph, extending it to 8-ft-diam only 4
               he reported. Beyond 550 mph the transonic problem   seconds later. Deceleration flaps and speed boards might
               caused the lift due to the car’s symmetrical nose shape   be helpful, and a small Jato thrust reverser could be
               and supersonic flow beneath it. Breedlove believes his  useful, but might present a retro-stability problem.




               and difficult, says Bill Bettes,   day is most impressive. They’re   produces only longitudinal aero­
               Director of Caltech’s 10-ft wind   already moving at high speed   dynamic effects which have no
               tunnel. “Most road tests can    with a drag rise and possible in­  effect on the lateral dynamics, if
               measure lift and drag forces,   crease in lift so the compressi­  vehicle is operated at constant
               pressure distribution and wind   bility effects are important con­  speed. Thus the entire gust re­
               noise location. But you can’t get   siderations in design. Some of   sponse is due to the cross wind
               steady state forces, rolling or   them have already entered tran­  velocity components.
               yawing moments. And you can’t    sonic speed ranges where a        The researchers believe a full
               get much input for lateral sta­  local flow along certain sections   scale road test program is now
               bility data.”                    of the body may exceed Mach 1.  indicated using a highly re­
                 Wind tunnel testing, says        Roger Hawks, University of    sponsive vehicle such as a VW.
               Bettes, gives you control over   Maryland, and Eugene Larrabee,   Such a test would measure the
               ambient conditions; control of   MIT, report that the influence   force of the moment induced on
               attitude of model vehicle. And   of cross wind disturbances on   the vehicle by vertical gradients
               you can measure various mo­      vehicle aerodynamics is ap­     in the cross wind.
               ments data using handy tech­     preciable. “From wind tunnel      At the Los Angeles aerody­
               niques not useful on the road.   test data it appears that the   namics meeting it became ap­
               And most important, in the wind   vertical gradients of the cross   parent that there’s a general lack
               tunnel you can make major con­   winds play a large role in re­  of standards for race car design.
               figuration changes quickly and   sponse of vehicles to gusts.” A   This includes both a lack of
               evaluate them.                   gust acting on an auto has two   standard testing procedures and
                 The case for wind tunnel test­  results, one parallel to the di­  a common technical language on
               ing high speed land vehicles at   rection of vehicle motion and one   which to base engineer-designer-
               the speeds they are attaining to­  normal. The parallel component   driver discussions.

          August 1, 1968                                                                                     25
                                                                                                                  24
   2   3   4   5   6   7   8   9   10