Abhi - Stealth is affected by followign factors as per Wiki.
Factors affecting Stealth of Aircraft
Size
As a rule, the larger an object, the stronger its Radar reflection and thus the greater its RCS. Also, Radar of one band may not even detect certain size objects. For example. 10 cm (S-band Radar) can detect rain drops but not clouds whose droplets are too small.
Material
Materials such as metal are strongly radar reflective and tend to produce strong signals. Wood and cloth (such as portions of planes and balloons used to be commonly made) or plastic and fibreglass are less reflective or indeed transparent to Radar making them suitable for radomes. Even a very thin layer of metal can make an object strongly radar reflective. Chaff is often made from metallised plastic or glass (in a similar manner to metallised foils on food stuffs) with microscopically thin layers of metal.
Also, some devices are designed to be Radar active, such as Radar antennas and this will increase RCS.
Radar absorbent paint
The SR-71 Blackbird and other planes were painted with a special "iron ball paint". This consisted of small metallic-coated balls. Radar energy is converted to heat rather than being reflected.
Shape, directivity and orientation
The surfaces of the F-117A are designed to be flat and very angled. This has the effect that Radar will be incident at a large angle (to the normal ray) that will then bounce off at a similarly high reflected angle; it is forward-scattered. The edges are sharp to prevent there being rounded surfaces. Rounded surfaces will often have some portion of the surface normal to the Radar source. As any ray incident along the normal will reflect back along the normal this will make for a strong reflected signal.
From the side, a fighter plane will present a much larger area than the same plane when viewed from the front. All other factors being equal, the plane will have a stronger signal from the side than from the front so the orientation between the Radar station and the target is important.
Smooth surfaces
The relief of a surface could contain indentations that act as corner reflectors which would increase RCS from many orientations. This could arise from open bomb-bays, engine intakes, ordnance pylons, joints between constructed sections, etc. Also, it can be impractical to coat these surfaces with radar-absorbent materials.
------------------------------------------------------------------------------------------------------------------------------
This article does not mention anything about heat and infrared signatures.Arent these also a factor in RCS?
