Stealth Technology

¶ 6. Stealth Technology

The stealth characteristics of the F-35 are based on several complementary technologies [29].

¶ Radar Cross-Section (RCS)

The estimated RCS of the F-35 is approximately 0.001–0.01 m² in the frontal hemisphere – comparable to the size of a golf ball [30]. This value applies to X-band frequencies, as used by most tactical radars.

¶ Airframe Shaping

Edge Alignment: All edges (wing edges, tail edges, bay doors) are aligned to a few common angles to deflect radar energy in predictable directions
Continuous curvature: No sharp transitions in the airframe geometry
Sawtooth panels: Maintenance panels with sawtooth edges to scatter edge reflections

¶ Radar Absorbing Materials (RAM)

The F-35 uses Fibermat technology – radar-absorbing materials baked directly into the outer skin [29]. Compared to the F-22's glued-on RAM coatings, this is more corrosion-resistant and lower-maintenance.

¶ Diverterless Supersonic Inlet (DSI)

Instead of a conventional splitter plate, the F-35 uses a compression bump ahead of the engine inlet [31]. Advantages:

~30% weight savings over conventional inlets
Elimination of the splitter plate as a radar reflector
Functional up to Mach 2.0 (tested on a modified F-16, December 1996)

¶ Luneburg Lens Reflectors

For peacetime flights and exercises, 4 Luneburg lens reflectors (2 top, 2 bottom) are fitted, deliberately increasing the RCS [32]. They are removed for combat operations.

¶ Limitations

Against VHF radars (Very High Frequency, wavelength ~1–3 m), stealth aircraft like the F-35 are significantly more visible due to resonance effects [33]. Russian systems such as the Nebo-M specifically exploit this.

¶ References

[29] Wikipedia: Lockheed Martin F-35 Lightning II – Design
[30] GlobalSecurity: Stealth / Low Observable Technology
[31] Wikipedia: Diverterless Supersonic Inlet
[32] The Aviation Geek Club: Luneburg Lens Radar Reflectors. 2022
[33] Fly a Jet Fighter: The F-35 Facing Russian and Chinese VHF Radars. 2023