Let us take a look at the 'Hopeless Diamond'...
F-117 History
Hopeless Diamond
During 1975, Skunk Work engineers began working on an aircraft which would have a greatly reduced radar cross section that would make it all but invisible to enemy radars, but would nevertheless still be able to fly and carry out its combat mission. The technique that they came up with was known as faceting, in which the ordinarily smooth surface of the airframe is broken up into a series of trapezoidal or triangular flat surfaces. The surfaces were arranged in such a way that the vast majority of the radar incident on the aircraft will be scattered away from the aircraft at odd angles, leaving very little to be reflected directly back into the receiver. An additional reduction in radar cross section was to be obtained by covering the entire surface of the aircraft with radar absorbent material (RAM). One of the disadvantages involved in the use of faceting on aerodynamic surfaces was that it tended to produce an aircraft which was inherently unstable about all three axes - pitch, roll, and yaw.
In the beginning, Lockheed created, not an aerodynamic model, but a low radar observable one. Lockheed engineers wanted to see how far they can 'push' this envelope. The result was the 'Hopeless Diamond' that is less radar reflective than the current F-117. The negative to that was the shape was so unflyable no matter how much they toyed with flight controls avionics and algorithms. As the shape evolve into a design that is controllable, could accommodate a pilot and some weapons load, the evolved design became more radar reflective than the 'Hopeless Diamond' shape.
This led to the philosophy of 'balanced stealth' where the aircraft should have these 'low points':
- radar reflection
- infrared
- acoustic
- visual
- contrails
- engine exhaust
Is it desirable to have zero infrared or exhaust emission? Yes, but if the aircraft is detectable in radar reflection or contrails then the cost and expense of reducing infrared and exhaust to zero was excessive. When cost is taken into consideration, and we must, then
ALL detectable signatures should be reduced to a proportionate level to each other. In other words, testings should be done so that once infrared emission is reduced to where radar reflection became the dominant signature, time to stop work on infrared and redirect resources to reduce radar reflectivity.
This is very much applicable to modifying an existing aircraft design to become more 'stealthy' than its previous evolution, as in this 'balanced' approach.
Take the current JF-17 and measure its 'clean configuration' RCS. Then gradually load it with the various external doo-dads such as bombs or fuel tanks or targeting pods. All along the way take RCS measurements, the more precise the better. Now work on the base airframe. Install all the RAM anywhere possible. Shape the outer body as much as possible without compromising
ESTABLISHED aerodynamic stability.
Now here is the clincher...
If, once re-loaded with all the various configurations of external doo-dads, this newly evolved JF-17 does not record at least a %50 reduction in measurable RCS at the same distance from prior measurements, then it is clear that the majority of the radar reflectivity came from the externals and not from the aircraft itself. This is why the RCS of a clean F-16 at 150-200 km distance is the official 'unofficial' standard for RCS reduction goal, either for a new design or modifying an existing one. The F-16 is small enough to make it difficult to detect across the entire spectrum and most fighter aircraft's radar antenna size limits their effective range to between that 150-200 km.
Same for infrared. For the modified clean JF-17, did its lowered radar reflectivity factor elevate infrared emission to the highest vulnerability? If yes, then stop working on radar reflectivity and redirect resources to do something to the engine. Once all known efforts tried and still infrared give the aircraft away
BEFORE its radar reflectivity does, then a somewhat 'balanced' reduction between radar and IR have been achieved.
Same for contrails. If some outer airframe modifications to reduce radar reflectivity increases contrails, then one must bear the cost of such a wasted effort. Contrails should not be taken lightly. At the right environmental condition, an aircraft's contrails can be as nearly visible as the radar detectability distance. No shortages of contrails stories from WW II or later. Or this ==>
Contrail Science - The Science and Pseudoscience of Contrails and Chemtrails
So is it possible to reduce the JF-17's detectability across the known spectrum? Yes. But one does not know to what degree until there is a dedicated exploratory program for it. Good luck.