1. Lockheed L-1011
The most elegant of tri-jets, the TriStar suffered from delays due to Rolls-Royce’s failure to deliver engines on time, as well as being heavier and less efficient than promised. 250 were produced, but this was well less than required to break even leading to Lockheed’s exit from the commercial market.
2. Douglas DC-8
Flying just months after the similarly sized and configured Boeing 707, the DC-8 was a major success for Douglas selling over 500 aircraft.
3. Douglas DC-10/McDonnell Douglas MD-11
Douglas’ smaller answer to the 747, the DC-10 was never able to match the 747's success, though superior engine options gave it an edge over the competing Lockheed TriStar. The MD-11 was developed as a more advanced version after Douglas’ merger with McDonnell, and production was halted following Boeing’s acquisition of McDonnell Douglas in 1997 to avoid internal competition with the 747, 767, and 777.
4. Douglas DC-9/McDonnell Douglas MD-80/MD-90
Having produced a long-range narrow body airliner in the DC-8, Douglas turned to building a cheaper short haul jet. After a failed attempt to sell a license built version of the Sud Caravelle, they designed an entirely new airliner using the Caravelle’s innovative configuration. The new aircraft family was a massive success 3rd only to the 737 and A320 in terms of sales. After Boeing took over, a version was produced as the 717, and the Chinese Comac ARJ21 is produced using tooling left over from license-built production in China.
5. Convair 880/990
The vastly less successful contemporary of the 707 and DC-8, Convair hoped to differentiate themselves with a faster aircraft even though that required higher operating costs and lower seating capacity. It did not work out, and production was ceased after just over a hundred planes were produced. Convair under General Dynamics shifted into a supporting role talking on a subcontractor role for other aerospace companies. They did propose a small twinjet, the 660, to compete with the 737 and DC-9 that featured engine nacelles integrated into the top of the wing, but it never advanced beyond the design stage.