Americanís president, C.R. Smith, envisioned a high-speed transcontinental service that would operate at a blazing 635 mph, shaving as much as 45 minutes off of the 707 and DC-8 operating times for a New York-to-Los Angeles flight. Desperate to make its jet airliner program viable, Convair agreed to meet Americanís speed requirement by upgrading the 880 with a fuselage stretch of 10 feet to increase seating capacity, more powerful General Electric CJ-805 turbofan engines (the first time an airliner had been designed around turbofans), anti-skid brakes (another airliner first), enhanced landing gear and a hydraulic rudder control system. In addition, Convair contractually guaranteed that the new plane would be able to achieve a 635 mph cruising speed, with significant cash penalties paid to the customer airline if that speed performance could not be met. Convair was putting its soul on the bargaining table just to keep in the game.
The resulting aircraft, which essentially became a new model rather than simply an upgraded 880, was launched as the Convair 990 in August 1958 with an American Airlines order for 25 aircraft. The lengthened fuselage allowed an increased seating capacity of 98-110 in a typical two-class configuration, and maximum range was extended to 4,400 miles. The only other customers at this point were SAS, for two planes, and Swissair, for seven, replacing an earlier Swissair order for five 880s.http://www.airliners.net/aviation-articles/read.main?id=67
(gives range of 4400 miles (3823nm))http://www.aviastar.org/air/usa/convair-990.php
(gives range of 990 as 3800 miles (3302nm))http://www.super70s.com/super70s/tech/aviation/aircraft/Convair-990.asp
(gives range of 990 as 3200 miles (2780nm))
Early American Jetliners by Ugo Vicenzi lists the ranges of the Convair jets as follows:
CV880 5040km (2719nm); CV880M 5450km (2940nm); CV990 6115km (3299nm)
However I accept that in practice the 990 failed to meet American's requirements and could not reach the 635mph speed written into the contract and could not make the JFK-LAX run with a full load. The point I suppose is what loss of load resulted from attempting the run in one jump and frankly I could not make a profit on them anyway so have bankrupted out and tried again with different airliners.