Originally Posted by
MSOCS
Or, you incorrectly assume that only engineers know or understand such things. One could assert the signature of a Russian fighter as, say, 10dbsm clean and 15dbsm with a set of stores. Now take a generic stealth fighter with -20dbsm clean, for example. Add the same stores and let's say it becomes -10dbsm or -5dbsm. That's still a multiple order of magnitude lower than the 15dbsm Sukhoi.
As I said earlier, Mach 2 is entirely correct. Without proof - which is highly guarded - it's a road to nowhere when the cognoscenti demand evidence that isn't 'out there'. LO's figures from his earlier argument are just as indefensible as those in the example above.
Well I have done some work in this area so I’ll attempt to explain some of the issues.
As has been pointed out I believe you do not understand RCS when expressed in decibels. We use decibels (dB) because radar respond to a reduction in RCS in a logarithmic manner.
The decibel (dB) is a logarithmic unit used to express the ratio of two values of a physical quantity, often power or intensity. One of these values is often a standard reference value, in which case the decibel is used to express the level of the other value relative to this reference. The number of decibels is ten times the logarithm to base 10 of the ratio of two power quantities or of the ratio of the squares of two field amplitude quantities.
Radar Cross Section (RCS) is measurement whose units are surface area, typically recorded in square meters. Since RCS is a quantity that can change several orders of magnitude as the angle between the radar and the target varies, usually the base 10 logarithm of the linear RCS is used to show the RCS in plots. It is routine to see the RCS represented this way in dBsm, or decibel square meters.
Even a small panel that's not properly installed can destroy an aircraft's low signature. If a tanker were to damage the surface of a stealth aircraft, it could also spell trouble.
To put it another way, if I use your math I could put eight weapons each with a 1 square meter RCS (1 m2 = 0 dBsm) and not change the signature of the system at all. Or even better, I could mount a very small sphere with a -50 dBsm RCS to an aircraft with a -30 dBsm signature and have a system with a -80 dBsm signature.
External store signature will overwhelm the total signature of the aircraft. While I don’t have a good reference for the RCS of various external stores I will look at a theoretical example. For a given radar with an effective radiated power of x-watts, a low signature aircraft with external stores having a very small signature of 0.1 mē RCS would be detected at 112 NM and a stealth fighter of 0.001 mē (-30 dBsm) RCS would be detected at 36 NM.
If you put the external stores on the aircraft the radar will see the 0.1 m2 and the 0.001 m2 aircraft is inconsequential.
Also, when looking at external stores please note that the measurement of RCS in meters squared does not equal geometric area. A perfectly conducting sphere of projected cross sectional area 1 meter square (i.e. a diameter of 1.13 m) will have an RCS of 1 square meter. However, a square flat plate of area 1 square meter will have an RCS of σ = 4π A2 / λ2 (where A=area, λ=wavelength), or 13,982 square meters at 10 GHz if the radar is perpendicular to the flat surface.
So external stores with a 0.1 square meter is very small indeed.