It is Boeing's latest idea for a design refresh that retains the wing and T-tail, but narrows the fuselage by 4ft.
Boeing unveiled the idea for a more "fuel-efficient" C-17FE at a lightly attended press conference today.
The design concept shrinks the airlifter's cross-section to the minimum required to accommodate a fully armoured Stryker vehicle, says Tom Dunehew, vice-president of C-17 business development.
As a trade-off, the C-17FE will not be able to carry an unspecified list of outsize equipment, but Dunehew declined to name them.
The idea also borrows upgrades from Boeing's earlier concept for the C-17B, including improved flaps, a 13% engine thrust upgrade and a precision landing augmentation system. Unlike the C-17B, the fuel-efficient concept omits the addition of a centre-line landing gear.
Dunehew also declines to estimate development costs, but says it would cost far less than to design an entirely new airframe. He acknowledges that launching the programme would require a significant order to justify the development costs.
Boeing is continuing to evaluate new designs for the C-17. Asked whether Boeing has ever considered installing GE90-class engines on a twin-engined C-17, Dunehew replied that it was feasible. However, as a tactical airlifter, four engines are necessary to minimise the risk of a crash caused by an engine-out problem on take-off.