Hesham: Some minor nit-picking. This was a Canadair design not Bombardier (which didn't buy Canadair from the Government of Canada until August 1986). The
Challenger E study was drawn up in February 1978. It was only designated CL-610 later.
Some details: A prototype was meant to fly in 1982 with deliveries beginning in 1983. The
Challenger E featured a 105in (267cm) stretch. The airline version is quoted in
Wikipedia as being a 24 pax aircraft but it was actually to sit up to 40 pax (32" seat pitch). The range (with 40 pax) was to be 1,700 nm (3,200 km) with 40 passengers. According to
Flight, Canadair was "studying the potential of the type in the light of new interest in full-fare 'business class' services. But the basic executive versions of the
Challenger have now proved successful on the market , and the company may not pursue studies of an airliner version."
http://www.flightglobal.com/pdfarchive/view/1981/1981 - 0801.html [dead link]
Wikipedia's potted history of the CL-610 is a bit garbled ... although, to be fair, they are paraphrasing
Flight International (04 April 1981, p.974) --
http://www.flightglobal.com/pdfarchive/view/1981/1981 - 0948.html [dead link]
Federal Express was the launch-customer for the CL-600 -- indeed, it was FedEx who dictated that unfortunate engine choice, the ALF-502L. Contrary to
Wiki/Flight, it was the FedEx order for 25 x CL-600s which was cancelled. FedEx cited the 03 April 1980 crash of prototype CL-600-1A11 C-GCGR-X; Canadair's failure to achieve full type certification (mostly due to icing problems); and expected delivery delays (due to a shortage of engines); amongst other reasons.
Flight was talking about US industry de-regulation overturning aircraft size restrictions (imposed by the 1938 Air Cargo Bill). Those changes didn't
threaten the
Challenger E, they
inspired its design. With the FedEx CL-600 orders imperilled, Canadair decided to enlarge the design to better fit FedEx's new opportunity.
Rather than being tempted by a stretched CL-600 with ALF-502s, FedEx went with even larger B727-22Cs. Canadair then respun the
Challenger E as a pax aircraft. It was also to receive the GE GE GF34-1As. Canadair eventually gleaned 49 firm orders for the CL-610 (with another 30 possible orders). But, in 1981, it was realized that the CL-610 would be seriously overweight and needed redesign. By then, Canadair was crippled by debt and the market was turning ugly. Canadair dumped the CL-610 to focus on delivering CL-600s and getting the CL-601 ready for service (Sept 1982).
All of this is from my rough notes so, alas, I can't give sources. BTW, another unrealized development was the short-range, 43,000 1b Canadair
Challenger S aimed at service entry in the early '90s.