a question on radar and stealth

I only just thought about this.

a US stealth planes uses RAM and special shaping to become a stealth plane but what material does it use for the nose cone? If it uses a RAM material it will absorb its own radar and will be blind. If it uses normal titanium then surely it will stand out on radar more?

Justin

Originally posted by justin_barton3
I only just thought about this.

a US stealth planes uses RAM and special shaping to become a stealth plane but what material does it use for the nose cone? If it uses a RAM material it will absorb its own radar and will be blind. If it uses normal titanium then surely it will stand out on radar more?

Justin

I'm quite sure (but not 100% admittedly) that they use a RAM material tuned to the frequencies used by the radar itself. So it will let the radar work on the frequencies it uses, and absorb the others.

I'm quite sure (but not 100% admittedly) that they use a RAM material tuned to the frequencies used by the radar itself. So it will let the radar work on the frequencies it uses, and absorb the others.

cheers kilcoo that would make sense

Justin

easy the F-117 does not have radar for that exact reason!

Other options are available as well, such as a radar transpartent nosecone, then simply shaping or angling the radar dish in a convienient way.

The F-22 uses a radar that has many small antennas mounted all over the fuselage. It takes the information from all the antennas and puts it together into a picture on the screen. The advantage of this is that it uses small antennas all over the airframe that aren't going to create huge radar returns like the standard antenna would, and it gives a wide field of view.

As was stated the F-117 doesn't have radar, and I BELIEVE that the B-2 uses a system similar to the F-117 as there's not room in the nose section, or an area to access a radar antenna.

The AN/APG-77 radar has been developed for the F-22 by the Electronic Sensors and Systems Division of Northrop Grumman and Raytheon Electronic Systems. The radar uses an active electronically scanned antenna array of 2,000 transmitter/receive modules, which provides agility, low radar cross-section and wide bandwidth. Deliveries of the AN/APG-77 began in May 2005.

www.airforce-technology.com...

The B-2 radar requires an upgrade called the Radar Modernization Program (RMP) to move the radar to a new operating frequency. This upgrade is necessitated to avoid interference with primary authorized users of the current B-2 radar frequency. The RMP will feature an active electronically scanned array and is scheduled to undergo IOT&E in FY07. The B-2 was employed in combat operations during Operation Allied Force (March through May 1999), Operation Enduring Freedom (October 2001), and Operation Iraqi Freedom (March through April 2003).

www.globalsecurity.org...

Ok, the B-2 uses a Ku band Synthetic Aperture Radar (SAR).

Synthetic aperture radar (SAR) is basically a method of ground mapping that uses computer processing to make radar work better. It first appeared in the early 1950s but didn't reach a high state of development for almost 30 more years with the introduction of digital processing and other advances.



SAR yields high-resolution, photograph-quality images because it combines radar images made many miles apart. SAR uses antennas positioned on moving bodies, such as satellites, and then mathematically combines the separate signals transmitted as the antenna moves, simulating or mimicking the transmission of radar from a source with a larger “aperture,” or a larger opening. For instance, a European Space Agency satellite with a 10-meter SAR antenna mimics the performance of a 4-kilometer-long stationary antenna. The motion of the satellite, combined with the wide beam of the radar, covers a swath along the ground, allowing a large area to be searched quickly--typically 256 square kilometers. If a few dozen of these swaths are collected, an area of several thousand square kilometers will be covered.



One use for SAR is in searches associated with satellite-based search and rescue systems.

www.centennialofflight.gov...

They don't have need for an A2A capability on the B-2 so this is the perfect system for them, as it allows for targeting and also for Terrain Following.


[edit on 4/5/2006 by Zaphod58]

A very good source www.codeonemagazine.com... which among other things highlights the difficulties faced with stealthy radomes...

The Lockheed Design

After a poor showing in the concept exploration phase, Lockheed had to turn around its ATF program before the next proposal was due. The company had just lost what became the B-2 with a faceted design to a more aerodynamic flying wing design from Northrop. Lockheed had also been cut from consideration in the Navy's Advanced Tactical Aircraft program after entering that competition with a highly faceted design. The Air Force's response to Lockheed's concept exploration proposal forced the company to rethink its commitment to faceting for stealth.
..../////....
The Lockheed configuration quickly progressed from faceted to smooth. The configuration just preceding the company's final dem/val design, called Configuration 084, was smooth except for a faceted nose. "We knew how to make a stealthy flat radome," recalls Osborne, "but we didn't know until early 1985 how to make a stealthy curved radome. We started drawing them in late 1984, before we knew how to analyze them."

Originally posted by Zaphod58
The F-22 uses a radar that has many small antennas mounted all over the fuselage. It takes the information from all the antennas and puts it together into a picture on the screen. The advantage of this is that it uses small antennas all over the airframe that aren't going to create huge radar returns like the standard antenna would, and it gives a wide field of view.

As was stated the F-117 doesn't have radar, and I BELIEVE that the B-2 uses a system similar to the F-117 as there's not room in the nose section, or an area to access a radar antenna.

I was under the impression the F-22 still has a conventional 'single' radar antenna (well, AESA - you know what I mean ), and the distributed system (like radar in the wing LE) you talk about was going to go onto the craft at some stage down the line (like a 'block' upgrade)