In principle, the F-16U is a return to the F-16XL, which General Dynamics demonstrated in 1983. In both cases, the goal is to increase the F-16's range by adding internal fuel and decreasing the drag of external weapons.
The F-16U has a 1.4m fuselage stretch and a 65 sq m cropped-delta wing. The plan-form, large-area leading-edge flaps and twist and camber draw on F-22 experience, but the structure (aluminium alloy ribs and spars and composite skins) is different. The wing is bigger in span and area and deeper in section than that of the XL and, together with the fuselage stretch, increases internal fuel capacity to more than 7200kg - well over twice that of the F-16C. Wing root troughs hold four AIM-120s, and underwing hard-points can carry four 970kg weapons or eight 450kg weapons in addition to a pair of AIM-9s. Sweep angles are selected to reduce radar cross-section (RCS).
Rough calculations suggest that the fully loaded F-16U has about the same fuel fraction as an F-15E with the same weapon load and a centreline fuel tank. The F-16U has lower-drag AIM-120 carriage, no LANTIRN pods and no external fuel, so Lockheed Martin claims of equal or better range should not be dismissed.
The F-16U will be about 25% heavier than the F-16C but should turn better, even with the current 129kN versions of the F110 and F100, because of the larger wing. The F-16U is also designed to be more stable at high angles of attack.
A more powerful engine, however, is very desirable to restore acceleration. In August, General Electric plans to run a 155kN F110 demonstrator with a higher-airflow blisk fan based on F120 technology, matched to the F-16's inlet, and fitted with a scaled-up version of the F414's composite-lined augmentor. Pratt & Whitney may offer its F100-PW-229 Plus.
Lockheed Martin also believes that GE's Multi-Axis Thrust Vectoring (MATV) nozzle, tested on an F-16 last year, is mature enough to be offered on the F-16U, expanding its low-speed agility and flight envelope.
As proposed to the UAE, the F-16U will have a two-seat forward fuselage. Two-seaters will be needed for training and for some operational missions, and delivering all aircraft with the same external configuration saves development costs. The cockpit will be similar to the MLU, but with an added central MFD and LCD back-up flight instruments like those of the YF-22.
If its bid is successful, Lockheed Martin plans to spread the entire cost of development over the UAE's 80-aircraft order. The company believes that the difference in both acquisition and operating cost between the F-16C and the F-15E is so large that the F-16U can compete, even with a development bill (probably in eight digits) attached to each aircraft.