They did it with
F-15 Silent Eagle
Why not with JF-17.. Maybe a future upgrade... It wouldn't be as stealthy as a dedicated stealth fighter but reduces radar signature is always possible.
Am going to have to clear up a lot of misconceptions about radar detection and aircraft designs.
First...Radar detection is essentially a 'stochastical' process, fancy word for statistics or guessing. Say there are ten transmit pulses but only five echoes produced, it is now a %50 probability that there is <something> out there. For WW II era radar, that is acceptable enough to send out Spitfires to (hopefully) intercept Nazi bombers.
Second...Radar detection is about detection
AND identification of a target as far away from the transmitter as possible. It does not matter if the transmitter is ground or airborne. It does not matter if it is civilian or military. For a busy civilian airport, the more targets detected and the further the distance, the better the scheduling of take-offs and landings with plenty of time to spare for each. For the military, every target is suspect of being an armed hostile until proven otherwise -- Identification Friend or Foe (IFF). So it be good to detect anything as far out as possible in protecting a valuable asset, like the President or a nuclear facility.
So for today, when the military post a need for a radar system based upon the two above understandings, the demand will be something in the line of: 'The system
MUST be able to detect a target of 5m2 at 200km with a %90 probability.'
You cannot meet that criteria? You get no contract.
Now to the F-15SE.
When a design is under radar range testing, there will be a full scale model of the design perch atop a pylon and the model will be bombarded with radar signals of every freq bands from every directions.
Looks like this...
That is a full scale model of an A-12/SR-71, upside down and with no vertical stabs.
The F-15 base RCS value will be of a clean aircraft. The wings will have hardpoints but no pylons, hence no missiles or bombs installed. Those things can be added later for different testings.
Let us be generous and say the average RCS value for the F-15 is 10m2 at 400km. Round figures are easier to digest. If we want to install pylons and external stores, we have to ask what is the mission. An all missile configuration will be air superiority. Bombs will be for ground strikes. Add in external fuel tanks for both types. Each configuration will have an effect on the aircraft's average RCS value
OTHER THAN BASE. Bomb clusters are larger than air-air missiles. Now this ground strike configured F-15 has an average RCS value of 15m2 at 400km, for example.
An aircraft's RCS value is affected by atmosphere as well -- atmospheric attenuation or absorption. Transmitted pulses loses energy in their travel to a target, pulses that reflect off that target suffer the same fate in their travel back to the radar but we will ignore this factor for now. Anyway, if I can detect a target of 10m2 at 400km, I will be able to detect a target of 15m2 at 400km or if we take in atmospheric attenuation, the target was 15m2 at 500km but became 10m2 at 500km, possibly
FURTHER out. In other words, I can see the target just as clear at a further distance. Advantage to me. If I put an F-15 directly a few meters in front of a radar, its RCS will be infinite for that radar but still be 10m2 for a different radar 400km away. Or 5m2 at 800km. Or 'invisible' at 1000km.
But if I internalize missiles, bombs or even extra fuel with special compartments that conform to aerodynamics, the F-15's average RCS value may or may not increase from 10m2 at 400km. In other words, going back to the second understanding of radar application -- distance -- I have managed to increase several folds the lethality of my weapon without significantly increasing the effective detection range by the enemy's radar. If I alter slightly other structural items like canting the vertical stabs to remove large corner reflectors and install Radar Absorbent Materials (RAM), I could decrease the distance to 10m2 at 200km, which could translate to 5m2 at 400km, or 'invisible' at 600km, in effect, I moved the threat closer to the enemy or make it ambiguous for him to determine if there is a threat or not. Ambiguity, uncertainty and hesitancy have caused many battle losses.
Can the JF-17 be modified similarly to the new F-15SE? In my opinion -- highly unlikely.
The most capable jet fighters in the world internalized their engines. A single engine fighter like the F-16 have a tubular frame. The fuselage contain the frame. A twin engine fighter like the F-15 have a 'box' or 'box-like' frame. This is about mass centralization for maneuverability. The 'box-like' frame will be larger, it must be to fit two engines, hence a larger fuselage and that equate to greater flexibility in terms of modifications.
Conformal compartments are possible with the F-15 because it is a large and robust airframe supported by powerful engines. Do not be misled by news reports about the 'aging' F-15 fleet. Most B-52s are older than the people who flies and maintain them and the latest B-52 variant is a complement to the AWACS in terms of network centricity for the battlefield. The F-15 airframe can last for a couple more decades.
If the JF-17's internal frame is anything similar to the F-16, and from all visual indicators both are similar, then the aircraft is pretty much fixed as is. It could be more problematic and financially straining in trying to reduce the JF-17's RCS through after-the-fact methods. This is why the F-22 and the F-35 were designed from the ground up with 'stealthy' features built-in, not as add-ons, like the F-15SE.