>>>>> Bare registrerte brukere kan se lenker, Trykk her for å bli medlem av Milforum...

"Lockheed Gives a Peek at New JSF Stealth Material Concept

It is called "fiber mat," and Tom Burbage, executive vice president of F-35 program integration for Lockheed Martin says it is "the single, biggest technological breakthrough we've had on this program."

He says that a new process to blend stealth qualities into composite material avoided the need for stealthy appliqués and coatings. Using a new process, Lockheed officials are curing the stealthy, fiber mat substance into the composite skin of the aircraft, according to Burbage. It "makes this airplane extremely rugged. You literally have to damage the airplane to reduce the signature," he said in an interview with Aviation Week in Fort Worth. This top-fiber mat surface takes the place of metallic paint that was used on earlier stealthy aircraft designs.

The composite skin of the F-35 actually contains this layer of fiber mat, and it can help carry structural loads in the aircraft, Burbage adds."

Hva drev amerikanerne anført av Lockheed med for 50 år siden? Fra utviklingen av A-12/SR-71:

"We at the Skunk Works believed that the airplane's height and speed, as well as its pioneering stealthy composite materials applied to key areas of its wings and tail, would keep it and its crew safe, but we fortified that belief by adding a special additive, which we nicknamed "panther piss", that ionized the furnace-like gas plumes streaming from the engine exhaust. The additive caused enemy infrared detectors to break up incoherently. [fra boken Skunk Works av Ben Rich]


Den desidert største kilden til IR-emsjoner er motoren. Det gjelder først og fremst bakparten, dysen og jetstrålen. Og selvsagt om man ser rett inn på motorkomponentene bakfra.

Før i tiden, slik det var for B-2 og F-117, var motorene hyllevare. De var ikke laget for stealth og måtte begraves dypt i flykroppen for å skjerme de varme delene. I F-22-programmet ble det utviklet en ny generasjon turbinteknologi der stealth eller lavsignatur var et hovedkriterium fra starten. Som så mye annet har F-35 arvet også motoren fra sin forgjenger, skjønt med ny front og bakpart. Disse er spekket med ulike teknikker som forvalter IR- og radarsignatur:

"Pratt points out that the F119 and F135 are the only production engines with stealthy augmentors. Their design eliminates conventional spray bars and flame holders and integrates multi-zone reheat fuel injection into curved vanes that block the line-of-sight to the turbine."

Å skjule den glodhete turbinen for direkte innsyn er i seg selv et stort fremskritt.


Det ligger i kortene at mange av stealthteknologiene i F-35 er hemmelige, men den karakteristiske motordysen et av de synlige tegnene:

"The classified "sawtooth" features that ring the nozzle help consolidate the exhaust into a so-called "spike" signature, while other secret techniques have been employed to combat and minimize the engine heat signature.

"We had to deal with that, and we dealt with that," O’Bryan said, declining to offer details.

The F-35 meets or exceeds the services’ infrared signature specifications. Many of the standard fighter engine features such as a big afterburner spray bar assembly and related piping are missing from the F-35. The F135 power plant, built by Pratt & Whitney, is truly a "stealth engine," he said."



"LOAN provides a significant reduction in radar cross section and infrared signature emissions from the engine [..] With the LOAN, stealth is achieved through a combination of technologies. These include geometrical shaping, an advanced cooling system, and special coatings on internal and external structures. Due to the effectiveness of the advanced cooling system, the life of the nozzle divergent flaps will be more than doubled, resulting in significant maintenance cost savings"

Dysen benytter altså en rekke teknikker, kjølesystemer, keramiske materialer ol. som reduserer varmeutviklingen. Sikksakkformen på dysen sørger blant annet for at kald luft blandes raskere med den varme jetstrålen og kjøler den ned.

Man bør jo alltid ta rykter med en klype salt, men her en interessant kommentar av en av de mer kvalifiserte bidragsyterne i vårt forum på F-16.net:

It was rumored that the IR reduction would make the nozzle as cool as the airframe during AB operation and help defeat many of "today's IR missiles." The angled, notched, carbon-fiber eternal nozzle setments, or "turkey feathers" were designed to reduce RCS as well.

En annen teknikk som benyttes på F-22 og F-35 er såkalt 'maskering'. Flyskroget og halerorene skjermer de varme delene i ulike vinkler eller aspekter. Det kan for eksempelt skape forvirring for et IR-missil i et avgjørende øyeblikk: