Military Power

Stealth aircraft have played a significant role in recent conflicts, albeit in small numbers. During the first war against Iraq, only four of the 51 bombers used by the US Air Force were Northrop Grumman B-2 Spirits, while only twelve of the 293 "fighters" were Lockheed Martin F-117A Nighthawks.

While stealth aircraft have a reputation of being maintenance-hungry, this was not reflected in the mission-capable rates reported for the Iraqi conflict. Both the B-2 and F-117A achieved higher mission-capable rates than the best conventional combat aircraft – 85.0 per cent for the B-2, compared with 79.4 per cent for the B-52 and 89.3 for the F-117A, as compared with 84.1 per cent for the F-15E.

The ability of stealth aircraft to operate with near-impunity over enemy territory remains unique, though it must be said that during the air campaigns against the former Yugoslavia, Afghanistan and Iraq, losses for all types of manned aircraft have been extremely low. For example, Iraq failed to down a single US or British aircraft during the long-running campaign of air strikes against that nation in support of operations of the northern and southern ‘no-fly’ zones. During the war, Iraqi air defenses fired 1660 surface-to-air missiles and rockets, and the anti-aircraft artillery fired on 1224 occasions, yet the allied US losses to enemy fire were only four AH-64D Longbow Apache, two AH-1W Cobra and a single A-10A Warthog.

The first-ever downing of a stealth aircraft on 27 March 1999 was a significant propaganda boost for the Yugoslavs during the NATO air campaign against that country. The F-117A seems to have fallen victim to an S-125 (SA-3 ‘Goa’) missile - the wreckage showed the type of damage which would result from a near-miss detonation of a blast/fragmentation warhead.

Press reports have suggested that the stealth fighter was downed by a lucky shot from an S-125 battery, which had obtained some idea of the aircraft’s position from short-lived temporary tracks that had been established by widely-distributed radars or had detected the aircraft by using its back-up electro-optical tracking channel. The aircraft had just completed its attack, leading to speculation that the open weapon bay may have compromised the RCS for just long enough to allow the S-125 unit to begin tracking the stealth fighter.

Reports claimed that the US Air Force had grown careless in planning its F-117A missions, that the downed fighter had been using an egress route which had been used before and that EA-6B Prowler jamming aircraft tasked with protecting the strike were too far from the scene to be effective.

One intriguing suggestion is that the aircraft’s route may have taken it over a Yugoslavian test site used for radar or missile trials, giving experienced crews equipped with upgraded systems the chance to obtain a useful radar return.

First revealed in October 2002, some four years after it first flew, Boeing's Bird of Prey stealth technology demonstrator seems to have been intended to test new stealth technology. Privately funded by what was then McDonnell Douglas, it has a top speed of only 260 knots, which reflects its role as a flying testbed rather than the basis for a future combat aircraft. The wings are swept at around 65º, while the cockpit masks the inlet from the front view.

Some features of the design such as flexible hinge-line covers on the rudderons (a feature which would eliminate the radar ‘hot spots’ associated with skin gaps) have led to suggestions that the aircraft is intended to demonstrate RCS levels well below those of the F-117A, while the blue color scheme has led at least one observer to speculate that the Bird of Prey had investigated techniques for visual stealth which might allow a future stealth aircraft to operate by day.

The work on F-22 signature control was done using full-scale models. Flight tests of the aircraft’s stealthiness did not begin until several years into product development. Emphasis has also been placed on maintainability. Wherever possible, service points are located with weapons bays or wheel wells, while panels and other parts which must be opened during servicing will have specially-designed seals and gaskets. To avoid the need to repair low observable seals and coatings in the field, the F-22 has almost 300 specially designed access points. These include quick-access panels, featuring positive locks, seals and gaskets.

In the late 1990s came news of a new and novel technique for controlling RCS which could be fielded as an add-on or upgrade. Developed in Russia by the Keldysh Research Centre, it would protect an aircraft by creating an artificially generated plasma around it. Radar energy tends to pass around a plasma cloud rather than penetrate it, say the Russians, and the energy that does penetrate interacts with the plasma charged particles, and is partially absorbed. The hardware needed to create the protective screen weighs less than 100kg, and consumes between one and ten kW of electrical power. Ground and flight tests have shown that the radar observability of an aircraft can be reduced by a factor of more than 100, say the system’s developers. This would reduce the radar cross section of a MiG-23 from around 6 sq m to around 0.06 sq m.

In 1983, the Russian Air Force released its requirement for an MFI (mnogofunktsionalnyy frontovoy istrebitel = multifunctional front-line fighter). The resulting Mikoyan 1.44 twin-engined fighter was reported to make extensive use of radar-absorbent coatings, but development was protracted. Completed in 1991, it was placed in storage because the AL-41 engines were not ready. It did not fly until February 2000, by which time it was clear that the aircraft would never be placed in production.

China is known to have studied stealthy single- and twin-engine variants of its J-10A fighter. The Shenyang Aircraft Company has already been selected to lead research and development of a possible twin-engine heavyweight stealth fighter, and there have been suggestions that Chengdu might be ordered to work on a lighter single-engined design which could form the low end of a high/low mix of types. In early 1999, trials were reported of a Shenyang Aircraft Corporation J-8 (Finback) with some parts of its structure covered in Xikai SF18 radar-absorbent material, along with proposals to fit the same material to the Xian Aircraft Company JH-7 heavy fighter-bomber.

The US Navy plans to operate a Naval Unmanned Combat Air Vehicle (Ucav-N) from its aircraft carriers and has assigned the project to Boeing and Northrop Grumman, who are producing competitive designs. Boeing is offering the X-46, a design whose planform resembles that of the B-2 bomber. Northrop Grumman’s X-47A Pegasus technology-demonstrator, which made its first flight in February 2003, is a stealthy design with a diamond-shaped planform.

Work on stealth is underway in Europe. Germany independently developed the concept of faceting – as used on the F-117A – and started work on the Lampyridae (Firefly) programme in 1981. The resulting design used fewer facets than the F-117A.
A three-quarters scale model was test-flown in a wind tunnel, but although this had the potential to be developed into an operational aircraft, the project was canceled in 1987, apparently due to lack of funds.

MBDA-France has been developing active stealth systems that attempt to cancel the radar return from an airframe by transmitting a second signal of equal frequency and amplitude to the genuine return. Unlike Ram, this technique retains is effectiveness at low and medium frequencies, where the efficiency of passive stealth technology tends to decline. In 1999, the company conducted ground tests using a C-22 target drone fitted with an experimental active-stealth system, and flight tests conducted using ‘testbeds’ (probably C-22s) were carried out at the Centre d’Essais des Landes range at Biscarosse in southwest France. Possible applications for active stealth measures include the nose, seeker, wing-leading edges and engine air inlets of future missiles. France hopes to use such technology on the mid-life update of the Scalp EG air-to-surface cruise missile, and in next-generation supersonic missiles. Studies have been underway since the mid-1990s, when designers investigated a possible stealthy variant of the Apache with a redesigned fuselage of flattened triangular cross-section.

Sweden has been studying stealthy UAVs since the late 1990s. Saab Aerospace has flown a 50 kg subscale version of its proposed Swedish Highly Advanced Research Configuration (Sharc). A full-scale Sharc demonstrator would be 32 ft (10 meters) long, have a wingspan of 26 ft (8 meters) and a take-off weight of around 11,000 lb (5000 kg). However, there is currently no specific Swedish Air Force requirement for such a UAV.

Alenia Aerospace, BAE Systems, Dassault Aviation, Eads, Saab and other major European aerospace companies all recognize that the long-term requirements identified by European governments must be developed and demonstrated jointly. Stealth is one of a number of areas in which they plan to co-operate, though British participation could be made difficult by the prior existence of US/UK co-operative agreements.

Now that everyone has probably abandoned reading this thread on to the actual point. I have some questions... First, is stealth really as good as people think? Second, What is the best way to make an aircraft stealthy? If the comments on here brought up any questions, feel free to ask them.