The F-47

by David Archibald

26 March 2025

 

Above is some artwork released with the announcement of the USAF decision to proceed with the Next Generation Air Dominance fighter (NGAD). We can interpret it in the context of the history of US fighter aircraft to determine the likely attributes of the F-47.

Firstly, it is likely to be a single engine fighter. If it were a twin engine aircraft, the canopy would be just too large relative to the size of the aircraft. At one stage the NGAD development was going to cost US$300 million per aircraft. As aircraft costs have been US$4,000 per pound, that implies an aircraft weight approaching 30 tonnes. By comparison, the F-22 weighs 19.7 tonnes and the biggest fighter ever built, the Tu-28 of 1964, weighed 24.5 tonnes. The USAF can’t afford such an expensive fighter, so the notion of a low-cost version was floated a couple of years ago.

Low cost means one engine, which is fine. Back in the 1950s and 1960s, jet engines used to fail a lot. These days more fighter aircraft are lost due to bird strike rather to engine failure. Relative to the same power output, a second engine increases the capital cost of an aircraft by 20%. As operating costs are usually twice the capital cost over the life of the aircraft, having a second engine is a cost penalty equal to 40% of the capital cost of the aircraft. So, you must have a good reason to need a second engine.

This is the first fighter aircraft to have noticeably dihedral wings, which means that the wings are angled up from the horizontal. This shape is suggestive of a hypersonic glide vehicle, obtaining a lot of lift from the fuselage. In turn this means that the aircraft is optimised for high level flight, without much prospect of violent manoeuvring. Drag decreases with height as the air gets thinner, so this is a way of increasing range.

The biggest benefit from the dihedral wings would be its effect on radar signature. The ventral surfaces of the wings and the fuselage have the potential to be absolutely flat and thus most radar energy would bounce off at a low angle. At the same time, the upsweep of the dihedral wings would put the fuselage in a radar shadow.  It is a very promising shape in terms of low radar signature.

Dihedral wings also contribute to lateral stability, in what is likely to be a tailless design. Tails are a source of drag. They can be removed from the design if your software can manage the flaps correctly to maintain stability. This may also explain the canards, as another way of controlling yaw.

The last time the USAF had the opportunity to adopt such a stealthy design was the flyoff between the YF-22 and the YF-23 in 1990. The YF-23 was intrinsically stealthy from its shaping. One of the selection criteria was a combat range of 1,000 km.  The YF-22 won the competition but in development was found to need tonnes of radar absorbent material (RAM) spackled onto its skin to meet its radar signature requirement. This in turn reduced its combat range to 700 km. Maintaining the RAM on the USAF’s F-22s is half the hourly maintenance cost of US$85,000 per hour of flight. What was initially to be a fleet of 750 aircraft was stopped at 187. In effect, the F-22 was killed off by its own RAM. The wrong choice was made back in 1990 because of not thinking through the consequences of particular choices. By comparison, the F-47 is not going to need much RAM at all, if any.

The F-22 was followed by another debacle, the F-35, which was supposed to be the low-cost supplement to the F-22. Once again, the F-35 is hobbled by the choices that were made to make it the winner of the flyoff competition. After those two failures, the USAF got religion and did the design work for the NGAD itself, from first principles.

It is likely that the F-47 has a dorsal air inlet rather than inlets under the wings. This would bring two advantages. Firstly, it would leave the ventral surfaces of the aircraft absolutely flat, to minimise radar signature. Secondly, it would minimise the volume of the air duct to the engine, which in turn reduces the surface area of the aircraft. That in turn reduces drag, for lower fuel consumption and reduced radar signature. Traditionally, fighter aircraft have had their air intakes under the wings, because otherwise pitching up reduces the airflow to the engines and may cause them to stall. The Su-27 and the rest of the flanker family have been performing the cobra manoeuvre for decades, though, without that happening. A dorsal intake also eliminates the potential for foreign object damage to the engine by things flung up from the runway while taxiing. It allows for the optimum management of the real estate under the fuselage between the needs of the landing gear and the missile bay.

Next up is the weapons system. This is likely to be the AIM-174 which is the air-launched version of the SM-6 missile. The SM-6, mostly used as an air defence weapon by ships at sea, was created by mating the active radar seeker from the AIM-120 air-to-air missile with the body of the SM-2 Block IV missile. Ground-launched, it has a range of 400 km. Air-launched, without the booster, it has a range of 600 km.

The F-47 armed with the AIM-174 is in the ethos of the Mitsubishi G4M (Betty) bomber of WW2. Japan built 2,435 of these, with a return range of 3,000 km and armed with one torpedo. Allied ships that thought they were safe from land-based aircraft would be suddenly surprised by the appearance of a Betty bomber attacking them.

President Trump said that the fighter, named after him as the 47th president, has a speed of ‘2’. He means Mach 2. The first single engine fighter to reach Mach 2 was the Lockheed F-104 Starfighter in 1958. Its top speed was Mach 2.2 or 2,335 kilometres per hour. The F-47 is also the slipperiest fighter aircraft since the F-104, which would contribute to range and top speed.

There may be a new engine for the F-47, or perhaps the USAF could use an existing one. Using the F119 engine from the F-22 would mean an aircraft as large as the F-35. Its main sensor would be its infrared search and track (IRST). IRST only provides a bearing though, with no information on distance to the target. Using two F-47 in a flight of two would provide range data by triangulation. The F-47 is in a new subtype of fighter aircraft termed ‘penetrating counter-air,’ which means it will be able to approach enemy SAM systems and aircraft close enough to snipe at enemy aircraft with long range missiles. In particular, it could be expected to push enemy AWACS and tanker aircraft well back from the front line.  The USAF expects the F-15EX to perform traditional fighter work up to the front line, but not be able to enter the coverage of enemy SAM systems.

The F-47 could also launch long range antiship missiles, such as the PrSM Increment 2, against Chinese ships. The total range of the system in that case would be 3,000 km. X-47s could take off from Guam, top up their fuel tanks over the Philippine Sea and go on to sink Chinese invasion barges in the Taiwan Strait.

 

 

The design heritage of the shovel nose of the X-47 likely starts with a Northrop experimental aircraft called Tacit Blue, shown above. Tacit Blue flew from 1982 to 1985. Note the dorsal air intake, likely also copied in the X-47.

More recently, Scaled Composites, now owned by Northrop, produced an experimental aircraft called the Model 401 in 2017:

 

 

The slope angle of the dihedral wings is close to that of the X-47. Also note the dorsal engine air intake. This aircraft was likely made to test concepts for the NGAD program.

The combat role of the X-47 is the same as China’s new J-36 fighter. It flies high and fast, trying to remain undetected and flinging missiles at long range targets. The J-36 has three times as many engines though, and likely weighs three times as much, without much of an increase in combat efficacy over the X-47. The J-36 is not as slippery as the X-47 and may have more than three times the infrared signature at the same speed. In which case it may be possible that the X-47’s higher survivability more than offsets its lower missile loadout. It is also likely to be more cost-effective in sinking Chinese ships than Virginia class submarines.

How many F-47s could the US produce? In the mid-1980s, General Dynamics was producing the single-engine F-16 at a peak rate of 30 per month. The X-47 is about 50% larger than the F-16 but a similar production rate or higher would be eminently achievable.

 

David Archibald is the author of American Gripen: The Solution to the F-35 Nightmare.