Cancelled 707 variants:
- 707-520 Reengined 120 Reengined 120 with RR
Conway 10 engines.
- 707-520B 320B stretch 2' stretch of the 320B with JT3D-5A turbofans.
- 707-620 120 Stretch 10' stretch of the 120 with Bristol 511 engines.
- 707-720 320 with IGW Increased Gross Weight variant of the 320 with Bristol 511 engines.
- 707-320-101 320 with enlarged lower lobe 320 with an enlarged lower lobe for passenger seating on a lower deck forward of the wing and more cargo aft of the main gear.
- 707-520-X Double decker development Double decker with low wings. Length 191'7".
- 707-520-2X 520-X shrink Double decker with low wings. Shorter than the above.
- 707-520-X3 Double decker development Double decker with high wings. Length 144'2". Span 142'5".
- 735 and 738 Swing tail cargo variants 735 had an upward swinging tail and 738 a sideways swinging one. Both enabled cargo loading through the resultant opening.
Cancelled 727 variants:
- 727-100M Military Military version of the 727C with possible roles as Assault, staff and command transport, tanker, medevac and carrier onboard delivery(!)
- 727-300 Further Stretch 220 inch stretch of the -200 for passenger service with modified wing, bogie main gear and wide fan engines. Cancelled in favor of the 757.
- 787-300 Stretch Twin Project to make an evolved 727, with twin engines and winglets. The center engine was removed and a tail similar to that of late model MD
-80s ("flathead screwdriver") was added. Superficially similar to the MD
-80, but with the 727 fuselage width.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo