Do you think Rafale can beat F-35 and F-22 in head-on BVR fight?
Stealth is not magic in a duel between two aircraft, because if the stealth aircraft wants to take full advantage of its stealth, it must not use its radar. If it does use its radar, its opponent will detect it and will be able to concentrate its detection resources on the region where the stealthy aircraft is located, eventually finding a firing solution. And if the stealthy player doesn't use his radar, then his opponent is also stealthy.
Having described this main principle, I'm going to go into more detail, assuming a duel between the Rafale and an F-22, but a duel with an F-35 would also work in the same way.
First, let's suppose that the F-22 uses its radar. F-22 supporters will say that its radar is LPI and that the Rafale will therefore not detect it.
There are two ways in which a radar can be LPI: frequency band spreading and time spreading.
- Spreading the frequency bands consists of changing the transmission frequency continuously: for example, the radar on the F-22 changes frequency about 1000 times a second. Normally the enemy detection system sees anomalies in the electromagnetic reception rather than a radar, but the F-22's radar knows the sequence of frequencies it has used in transmission and can reconstruct the signal on reception.
- Time spreading consists of transmitting a long but weak signal, and compressing the return (this is done using Fourier transforms).
What counts for detection performance is the energy sent, i.e. the power multiplied by the time. The longer the transmission time, the lower the power, which makes detection harder for enemy systems, which will have to be more sensitive because they do not have the parameters needed for compression.
Translated with DeepL.com (free version)
To counter this, SPECTRA has two detection systems:
- a super-heterodyne narrow-band system that scans all the frequencies one after the other and is very sensitive: this system will detect radars that spread out in time but may miss those that spread out in the frequency bands because the transmitter and receiver would have to be very lucky to be tuned to the same frequency at the same time.
- A broadband system that monitors a large number of frequencies simultaneously but is less sensitive: this system will be perfect for frequency hopping radars that are powerful (and therefore easily detected) for a short time on each frequency they use.
What's more, SPECTRA has been improved for F4, with the sensitivity of the wideband system raised to the level of the sensitivity of the narrowband system.
What can the Rafale do once it has detected that there is a radar in a certain direction?
It can direct its optical resources, including its laser rangefinder, in that direction, or it can send more energy with its radar in that direction. I'll explain the latter:
What limits a radar's radiated power is not to fry its electronics, i.e. to pay attention to the temperature and therefore the heat generated, given the radar's heat extraction performance. If the radar is in search mode and scans a large area, the average heat generated must be less than the available heat extraction. For example, the RBE2 on the Rafale has a peak power of 10 kW (that's when it's transmitting) and an average power of 2-3 kW because it doesn't transmit continuously and the average is different depending on the mode.
However, if we know which direction we need to detect, we can send a signal that is not relevant to a search, but which is relevant for confirming a detection and measuring a distance. For example, we'll take a power of 3kw (which the heat extraction can evacuate), send a signal 1000 times longer than the usual signal (we replace the microseconds by milliseconds) and compress the return. Everything happens as if we had a radar with a peak power of 3000 Kw instead of 10 kw. This allows us to detect the F-22 much further away.
I have to stop now, but I'll continue as soon as I have time.