Thrust vectoring for fighter aircraft may be the most advertised and least used technology in the business. Three of the world's fighter-engine manufacturers are showing TV engines here.

Eurojet is displaying a TV EJ200, using the pitch-yaw axisymmetric nozzle developed by Spain's ITP and unveiled at Paris last year. The engine here has just completed its first ground tests. Although Eurofighter is publicly cool towards TV-arguing that the Typhoon is sufficiently agile without it-it is being considered for future upgrades.

General Electric has brought a YF120 prototype engine with the axisymmetric vectoring exhaust nozzle (AVEN). This combination was unveiled at Farnborough two years ago. GE has been approved to offer AVEN on the F110-GE-129 Enhanced Fighter Engine (EFE) for the United Arab Emirates' F-16 Block 60, and reveals here that it is looking at an improved axisymmetric nozzle that combines TV with low-observable features.

Pratt & Whitney is showing its UAE candidate engine--the uprated F100-GE-229A--fitted with the Pitch/Yaw Balanced Beam Nozzle (P/YBBN). It is currently flying on an F-15B under the USAF/NASA ACTIVE program.

What these nozzles have in common is that they are still waiting for anything that resembles a production order.

The reason for this is simple. Pull your fighter into a tailslide, cobra or any other ultra low airspeed maneuver over Farnborough. As you start to recover, count seconds. Imagine a circle around the fighter, growing in diameter at a mile per second. Count until you have accelerated back to 600 kt and regained your energy. The circle now covers half of Surrey. Any adversary inside that circle could have taken an IR missile shot, and there was nothing you could do about it .

This means that TV has to sell itself on its other advantages, which are less spectacular but more practical. TV can shorten take-off distances by allowing the fighter to rotate at a lower speed, and can shorten landing distances by adding pitch authority. TV provides a back-up control effector which could save the aircraft if the aerodynamic controls are damaged. TV may also allow some aerodynamic controls to be reduced in size or even eliminated, saving weight and reducing radar cross-section (RCS).

Minimizing control surfaces is one of the main aims of an emerging international program named Vector, sponsored by Germany, Sweden and the U.S. Navy. As currently planned, Vector has two phases. First, the remaining Daimler-Benz/Boeing X-31 research aircraft will resume its test program, probably with the goal of flying without a vertical tail. The same TV and control technology will then be applied to a modified JAS 39. Both the EJ230 and F414 are candidate powerplants.

Other fighter programs provide uneven support for TV. The first to enter production may be the Sukhoi Su-30M. The last 12 aircraft of the Indian Air Force order, to be delivered in 2000, are due to be fitted with TV nozzles.

The Lockheed Martin F-16 is available with TV for any customer who can fund final development. The UAE was cleared to receive TV, but so far has only elected to make power and control provisions for it.

The F-22 has pitch-only TV nozzles, but since the fighter has two-dimensional nozzles in any event (for stealth reasons) the direct weight penalty for TV is small. TV allows the F-22 to meet agility requirements with smaller tails, so the result is a net weight saving.

The Joint Strike Fighter teams are split. Lockheed Martin considered using a P/Y-BBN on the X-35, but has eliminated it to save weight and complexity. Boeing's X-32 has a 2D pitch-only nozzle based on F-22 technology, modified so that it can block the exhaust completely in jet-lift mode.

Dassault has yet to reveal any plans to put TV on Rafale, arguing that the fighter's agility and runway performance are adequate.

By Bill Sweetman