July 2001

A note on Stealth

Introduction

Stealth has been a very popular and much used word in recent times. New equipment has to be designed and built with stealth in it and in every conflict were western powers are involved, the use of stealth is something as a necessity, a God’s gift, a guarantee that you will win the conflict.

Stealth is often used with the name Low Obeservable’s, LO, which as the name says are the technologies used to minimise the chances to be located and identified. The stealth/LO technology is around us for many years and promises to be very effective if used correctly. The most known fact about stealth is that it decreases the Radar Cross Section, RCS, of a vehicle. The newest products have in the mean time achieved RCS factors which equal birds and insects. Were only the strongest of radars or innovative used radar systems or the use of a total different systems are able to identify Stealth vehicles.

Stealth is the ability to make radar detection very difficult if not impossible, the stealth vehicle is to absorb radarwaves, through Radar Absobent Materials, RAM, or by Radar Absorbent Structures, RAS, or to redirect the radarwaves, through the particular construction of the product to avoid detection. Stealth is however not limited to radar but also covers the limitation or even elimination of infra red, radio frequency and electronic emissions. In short the total emission management of a vehicle.

The effectiviness of stealth is only assured if combined with proper intelligence,

systems which can locate radars and identify them to evade them, surprise and ofcourse supporting aircraft like AWACS, EW and eventually fighter aircraft.

Stealth is a long known ability which has been known since many years.

The use of stealth will and has brought many advantages to the user, higher survivability of the crew and vehicle, higher chances on success and a bigger impact on the enemy, which is being attacked without knowing it in advance where and how.

The fundamentals of stealth were developed by the equations of the 19^th century physicist James Clarke Maxwell. Radar development and stealth are based on the computations of Maxwell on the absorption and reflection properties of electro-magnetic waves Many educated nations knew and know about stealth and research has been abundant on the subject. Not only the U.S.A. is busy with stealth also a number of European countries are committed to stealth. The U.S. advantage with stealth is about the integration and operation of complete stealth vehicles, and especially stealth aircraft. Europe’s stealth capabilities are at the moment more limited to ships, missiles and parts.

The use of stealth

Stealth can be used in aircraft, ships, vehicles, remotely piloted vehicles / unmanned aerial vehicles and missiles. The use of stealth in aircraft is widely known after the U.S.A. made their F 117 strike aircraft and later the B 2 bomber public. These aircraft, and especially their abilities to penetrate without being seen, played to fantasy of the people as if it was a plane from outer space.

But before the introduction the F 117 and B 2 research on stealth was already done by many countries in the western world. Research on stealth technology started already in world war II.

The research on stealth in the U.K. was closely connected with the research done in the U.S.A., In Germany they have executed and are executing stealth programs. They have proceeded very far with even a large scale model of a stealth aircraft called the Lampyridae, Firefly, which was designed to operate over the SAM and radar infested areas over the inner German border. This project was halted after massive U.S, pressure on the German government. France also has its stealth projects which was highlighted by the introduction of the Storm Shadow / SCALP EG air to surface missile, which is one of the first missiles boasting stealth capabilities. And by the La Fayette frigates which was the first frigate which was designed and constructed with stealth as the main design factor.

The La Fayette design was soon to be followed with the Dutch LCF frigate, the German F 124, A 100 and A 200 designs and by the U.S. planned DD 21 destroyer.

Land systems were also being designed with stealth on their mind. New Armoured Fighting Vehicles, AFV, were built to minimise the Infra Red emissions, the detectability by ground radars and ofcourse the visual appearance. Examples of these are the Leclerq main battle tank and the MRAV which is under development at the moment.

Further work has been done on RPV’s and UAV’s which incorporated stealth technology to increase their mission succes.

In all new designs stealth plays a major role but the implementation of stealth in aircraft is the most commonly known and the most eye catching.

The above mentioned F 117 and B 2 aircraft were the first which were designed completely with stealth as the most influential factor. Before those two planes other planes like the SR 71 and the U 2 recconaissance aircraft also used elements of stealth to increase their chances to survive on a mission over enemy territory.

The F 117 and the B 2 were designed to be very difficult to detect or even to be invisible to enemy radars. This was however not completely reached as, especially the F 117, they need careful intelligence about the whereabouts of enemy SAM systems, EW aircraft to accompany the ingress and egress routes and surprise to use their advantages and reach a high success rate. If one of these elements are missing the success rate gets lower very quickly.

The stealth factor was continued in the design of the F 22 Raptor air defence fighter and the planned Joint Strike Fighter. The F 22 and JSF combination should be the continuation of the F 15 and F 16 game. The F 22 is providing air defence, air dominance, and the JSF is the bomb truck. The JSF was therefore designed with as little as possible electronic equipment installed. This to keep the price low and to built a to the job aircraft.

The JSF programme is under threat by the new government as they might eventually skip a generation of aircraft and go directly to the Unmanned Combat Aircraft and/or built a F 22 in a strike version. There have been talks to built beside the 339 air defence F 22’s, 423 air to surface optimised F 22’s. This combination would be a very powerful instrument in the hands of the USAF, and would make the JSF superfluous. Existing F 16 block 50 or 60 and F18 E/F’s could easily make up the gap left, if the JSF will not be produced, until the Unmanned Combat Air Vehicles were to be introduced.

As things stands today the F 22 and the JSF are a new generation of aircraft which promise to deliver new opportunities in fighting and winning the next war. Higher strike rates, higher accuracy and lower fatalities on the own side.

The European aircraft programmes, the Eurofighter Typhoon and the Dassault Rafale, have also been designed with stealth on their minds. Not as rigorously as with the F 22 but on some aspects of the aircraft. Especially the front side is said to very small on radar screens.

Stealth has become an inseparable part in the design of new vehicles, equipment and ammunition. Existing vehicles and equipment is updated whenever it is possible and stealth assets are, were possible, included.

The limits of Stealth

Stealth is however not a magic instrument which can overcome all enemy defences. The defences not even need to be the most modern to be able to limit the effectiveness of stealth. And history has made this clear.

As have been made clear the use of stealth is, if it is succesful, will need something more than just a plane build according the highest stealth specifications. The plane itself will need advanced electronic systems to identify the radar systems and map a flight route through a radar field, it will need pre-strike intelligence about the whereabouts of radars and SAM systems, it will need to know about the capabilities and the signature of the radar systems, it will need surprise and it will need cover from AWACS type of aircraft, air defence suppression from SEAD aircraft and EW aircraft and eventually cover from air defence fighters. A succesful air strike with stealth aircraft is therefore more complicated and demanding as envisioned at the first look.

If one of the above mentioned elements is missing the succes of a stealth air attack will be much less certain. The level of succes will even reach the levels of an attack with coventional aircraft.

The undetectability/invisibility of stealth aircraft is much more limited as first presumed. Firstly the aircraft can only be used at night as the visual detectability is just as great as of conventional aircraft.. Secondly, the stealth aircraft have to carefully manage the emission of all possible sources, radio frequency, infra red and ofcourse radar. Stealth aircraft are just as vulnerable as non-stealth planes as systems like the Czech Tamara system will locate them just as easily, Tamara scans for emissions from the aircraft and then locates and identifies the source.

Thirdly, beside the mark one eyeball identification, a real time system of radars connected to one control side could also identify a stealth plane. This is at the moment not possible, at least not with current in service equipment.

Fourthly, the unconventional use of radars and the socalled radical radars. Radars can be shifted to a different spectrum were LO technology is not just as effective. And some LO materials are not very effective against low frequency radars as used in the older Soviet made UHF radars. And ofcourse new developments in radar technology will make the radar more capable and able to locate stealth aircraft.

A new kind of radar, the radical radar could also locate stealth aircraft. The use of Ultra Wide Band or bi-static radars could also identify stealth planes. There are still some problems with the new radars like the UWB radar require very high power to achieve long range detection and shaping techniques render them much less efficient than narrow band radars. With the bi-static system, the emitter and receivers are separated and need to be pointed at the the target in order for detection to take place. Searching a large volume in this way is difficult and would require a complex system of multiple platforms which is beyond the ability of many states. Both systems are therefore not available or operational yet. But future improvements may make the system more effective and operational.

Fifthly, another way to detect stealth aircraft is by detecting and tracking the inevitable disturbance all aircraft, stealthy or not, produce in their immediate environment. The most favored method is to exploit the disruption of commercial radiation transmissions blanketing the earth. These passive detection systems detect disturbances of FM radio, television and mobile phone waves/signals. This is a relatively cheap system as all transmitters are delivered with no cost an donly recevers have to be put in place.

And at last, stealth aircraft like the F 117 and the B 2 are not very good aircraft once detected and air defence fighters are sent to them. They are not designed for air to air combat or even to much self defence. These aspects would severely limit the chances on survival for the stealth aircraft.

A note on the side, the JSF is developed as a stealthy bomb truck, largely to keep cost under control, and only after massive pressure from the services and foreign potential customers it is included with some more electronics. The JSF was except from its stealth at the level of an F 16 A//B, where as the updated JSF will only reach the level of a F16 C block 50 aircraft. If the JSF would meet an updated F 5 or MiG 21 with a helmet mounted sight and advanced missiles it would have a very hard time to survive..

The weakness of stealth became visible as the Serbian/Yugoslav armed forces downed one F 117 and at least damaged one other. This was possible because of inadequate intelligence, the loss of surprise by using the same routes several times and the better placement of air defence systems / radars in anticipation of a coming raid.. The stories about a leak in western European defence circles about the strike routes of the U.S. stealth aircraft is nothing more than an attempt to save face. Or better to save the implacable reputation of stealth aircraft as superior invincible aircraft.

Conclusion

To put stealth in the right perspective, stealth offers a new capability which is very useful but it has to be used correctly and should not be overestimated. It is not a magic instrument which can overcome all defences. It has its weaknesses and new systems will certainly be able to detect stealth aircraft. It is like the competition between the anti-tank missile and the armour of a tank. There always will be a counter reaction to eliminate the advantage of the other. And the race with stealth and counter stealth is just to begin.

Not withstanding the counter stealth offensive which is about to be unleashed, the F 22, the B 2, the Typhoon and the Rafale remain very good aircraft which have a right to exist. They will improve the capabilities of the air forces using them.

The stealth factor is necessary to improve the survival of the aircraft and the success of the mission. The level of stealth is open to debate and depends on the specific role of the aircraft and the price the user is willing to pay. But to much stealth and especially to much reliance on it could proof to be very dangerous and costly. Cost in the procurement of the stealth aircraft and the risk of losing the aircraft as it ignores the dangers against it. Or better the limits of stealth.