Originally developed by UK manufacturer Hawker Siddeley in the 1960s, the Harrier emerged as the only truly successful V / STOL design of the many attempted during that era, despite being a subsonic aircraft, unlike most of its competitors.
32.
Supersonic flight at high altitude also places different stresses on the Concorde than those experienced by subsonic aircraft . For example, the rush of passing air on supersonic planes heats the skin above the boiling point, which can weaken the airplane's construction.
33.
With proximity fuze and fire-control radar, a dual 33 / 50 mount firing 50 rounds per minute per barrel was considered more effective than a quad Bofors 40 mm gun against subsonic aircraft, but relatively ineffective against supersonic jets and cruise missiles.
34.
Supersonic aircraft have poor lift / drag ratios at subsonic speeds as compared to subsonic aircraft ( unless technologies such as Variable-sweep wings are employed ), and hence burn more fuel, which results in their use being economically disadvantageous on such flight paths.
35.
World events had also dampened Concorde sales prospects, the 1973 oil crisis made many airlines think twice about aircraft with high fuel consumption rates; and new wide-body aircraft, such as the Boeing 747, had recently made subsonic aircraft significantly more efficient and presented a low-risk option for airlines.
36.
While the design was initially developed as part of the supersonic transport ( SST ) project at NASA, it has since been mainly applied to increase the fuel efficiency of many high subsonic aircraft . The supercritical airfoil shape is incorporated into the design of a supercritical wing.
37.
"The most exciting part about this airplane is the combination of technology in design and manufacturing means we will be able to bring this to market with operating costs very similar to today's subsonic aircraft . It will open up opportunities to all of us who fly today ."
38.
Although unknown at the time, compressibility was the cause of the phenomenon known as the sound barrier . 1940s-era military subsonic aircraft, such as the Supermarine Spitfire, BF 109, P-51 Mustang, Gloster Meteor, He 162, and P-80, have relatively thick, unswept wings, and are incapable of reaching Mach 1.0 in controlled flight.
39.
British Airways flies each of the seven Concordes in its fleet only three hours daily, he said, compared with more than seven hours daily flying time for the 757 and more than 13 hours for the 747-400; the plane also does not collect corrosive moisture _ as do subsonic aircraft _ because of the intense heat generated in flight.
40.
The carrier aircraft ( initially a NASA B-52, now an L-1011 owned by Orbital ) serves as a booster to increase payloads at reduced cost . is only about 4 % of a low earth orbital altitude, and the subsonic aircraft reaches only about 3 % of orbital velocity, yet by delivering the launch vehicle to this speed and altitude, the reusable aircraft replaces a costly first-stage booster.
