Proposed F-35F Long Range Variant

Hugh commented that a stretched fuselage and extra fuel tanks were added to single-engine aircraft fairly easily, but twin engines for the F-35 stealth multirole fighter is a major redesign. A simpler variant would have one engine, but a larger wing with greater fuel capacity for longer range and strengthened landing gear to handle the extra weight.

The resulting F-35F would be a medium bomber to replace the Australian F-111C and meet the requirements of the US Air Force Next-Generation Bomber. The aircraft would have advantages in commonality of training and maintenance with the F-35, while having three times the range.

However, the F-35F would have disadvantages. With a lower power to rate ratio, lower maximum speed and less manoeuvrability, this would no longer be a true fighter aircraft.

A single engine and single crew is unusual for a bomber. But single engine fighter aircraft with reliable engines and automation, are now routinely flown over transoceanic distances.

With modern military aircraft the problem is not so much the aircraft surviving in battle, but surviving a long development time and budget pressures, with the development of reliable electronics being a stumbling block. Building a variant of an existing aircraft with already developed and tested systems would outweigh the limitations of a derivative design. An aircraft which can be produced on time and on budget is more useful than one a decade late and too expensive to buy.

Proposed F-35D Long Range Variant

The Australian Government selected the Lockheed Martin F-35 Lightning II single-seat, single-engine stealth multirole fighter to replace the F-111C and F/A-18 Hornet. While a capable aircraft, the F-35 does not have the range of the F-111C. This will be made up for, to some extent, by the use of in flight refuelling, but a larger aircraft would be desirable. It would be feasible to produce a twin-seat, twin-engine, long range derivative of the F-35.

The F-35 "Joint Strike Fighter" was planned in three variants: F-35A conventional takeoff and landing (CTOL), F-35B short takeoff and vertical landing (STOVL) and F-35C carrier aircraft. A fourth variant was added in 2010, the F-35I for Israel, derived from the F-35A.

It would be feasible to add a fifth variant, the F-35D, derived from the F-35C, which has larger wings and tail control surfaces than the F-35A and B. The proposed F-35D Long Range Variant would differ from the F-35C by having a larger fuselage and wings, twin engines and a crew of two. The range of the F-35D would be three times that of the F-35C with the same weapons payload.

The F-35D development would be relatively rapid, low cost and low risk, compared to a completely new design. The F-35D would follow the approach taken with the successful development of the F/A-18E/F Super Hornet from the F/A-18C/D Hornet. More commonality with the existing aircraft would be possible than was the case in development of the F/A-18E. The sensors, computers and other electronic components of the F-35 could be used unchanged. Some components of the F-35 would be duplicated for the F-35D, such as the engines and cockpit instruments. Other components would be scaled up, such as the landing gear and the fuselage.

The Australian air-force requires only 24 long range aircraft to replace the F-111C and development of the F-35D could not be justified for this small production run. However, the US Air Force is investigating options for a Next-Generation Bomber. The F-35D would meet the requirements for such a medium bomber. It would have advantages in commonality of training and maintenance with the F-35.

In 2006 the Australian Department of Defence invited participation by Australian researchers in the F-35 project. One area for research could be for the Australian government to fund a small study into the feasibility of the F-35D and see if this sparked interest by the US Government.