"An integrated airframe design, advanced materials and an axisymmetric nozzle maximize the F-35's stealth features. A quick look at the aircraft reveals an adherence to fundamental shaping principles of a stealthy design. The leading and trailing edges of the wing and tail have identical sweep angles (a design technique called planform alignment). The fuselage and canopy have sloping sides. The canopy seam and bay doors are sawtoothed. The vertical tails are canted. The engine face is deeply hidden by a serpentine inlet duct. The inlet itself has no boundary layer diverter channel, the space between the duct and the fuselage, to reflect radar energy. And, of course, weapons can be carried internally. Each internal bay contains two hardpoints onto which a wide variety of bombs and missiles can be attached.
According to November 2005 reports, the US Air Force states that the F-22 has the lowest RCS of any manned aircraft in the USAF inventory, with a frontal RCS of 0.0001~0.0002 m2, marble sized in frontal aspect. According to these reports, the F-35 is said to have an RCS equal to a metal golf ball, about 0.0015m2, which is about 5 to 10 times greater than the minimal frontal RCS of F/A-22. The F-35 has a lower RCS than the F-117 and is comparable to the B-2, which was half that of the older F-117. Other reports claim that the F-35 is said to have an smaller RCS headon than the F-22, but from all other angles the F-35 RCS is greater. By comparison, the RCS of the Mig-29 is about 5m2.
Much has been improved between the design of the F-22 and the F-35. The F-35 doors for landing gear and equipment, as well as control surface, all have straight lines. The F-35 does not require "saw tooth" openings to divert RF energy. One reason the openings on the F-35 are straight lines is reported to be embedded electrical wires near the edges whcih interfer with RF signals. The F-35 RAM is thicker, more durable, less expensive and, being manufactured to tighter tolerances compared to that of the F-22. The tighter tolerances means less radar signal can penetrate openings and reflect back to its source. The newer RAM is more effective against lower frequency radars, and maintenance should cost about a tenth that of the F-22 or B-2. Some forms of RAM have have electrical plates or layers within the layers of carbon composits."
"Given that the dimensions of many of these shapes are of the order of metres, the application of absorbent or lossy coatings or laminates will not be sufficient to drive the critical lower hemisphere beam/side aspect signature down to values which qualify as VLO and thus “stealthy”. Refer Annex C."
1 site claims that the F-35 is barely VLO and the other claims the plane uses a blend of new materials and techniques.
Now Im sure neither site has clearance, so please give us your arm chair prognostication.