Frrom a former head engineer (weapons systems) at Dassault and EADS on IDF...
F 35 JSF v/s Dassault Rafale
Due to the MMRCA program the merits of Eurofighter Typhoon v / s Dassault Rafale was discussed at length on this site,. These two aircrafts represent the most advanced technology of Europe in this field. They are technically equal but meet different operational requirements.
The problem for the Typhoon is that the French are the only ones who have identified needs that correspond to the 21th century.
Typhoon is a very good plane that filled its specifications but now it must evolve to the specifications of the Rafale.
To facilitate the export of the aircraft, the program partners want to make believe this is easy. But if it was easy, French would not have left the program, they would have managed to get a satisfactory compromise.
From my point of view, F 35 JSF and Rafale meet closer needs, with similar technology, but with different doctrines of use. Their comparison therefore seems very interesting.
Joint Strike Fighter Stealth Capabilities
This paragraph comes mainly from: Assessing Joint Strike Fighter Defence Penetration Capabilities
The Joint Strike Fighter is an unusual airframe design, since it departs from many of the well established ground rules in stealth shaping, established in other designs such as the F-117A, B-2A, A-12A, YF-23A and F-22A Raptor. Stealth shaping is widely regarded to account for the first hundredfold reduction in aircraft radar signature, compared to non-stealthy designs of similar size, with application of lossy and absorbent materials used to further reduce the signature where feasible.
The first major departure from established shaping conventions is the angular or aspect dependency of the Joint Strike Fighters radar signature.
Diagram 3.
Diagram 4.
Diagram 4 summarises the qualitative comparisons of Joint Strike Fighter shaping aspect and band dependency, with green denoting performance which qualifies as Very Low Observable, yellow as Low Observable, and red as order of magnitude closest to conventional reduced signature aircraft designs. The aircraft performs best in the X-band, and Ku-band, with performance declining through the S-band with increasing wavelength. In the L-band the axisymmetric nozzle design no longer produces useful effect, and the length of the inlet edges sits in resonant mode scattering rather than clean optical scattering, degrading performance. In the VHF band (~2 metres) Joint Strike Fighter airframe shaping has become largely ineffective.
The aircraft will have a credible ability to defeat S-band search/acquisition radars, X-band engagement radars and X/Ku/K/Ka-band missile seekers only in the narrow ±14.5° angular sector under the nose. As the angle relative to the threat radars increases, the unfortunate lower fuselage shaping features will produce an increasingly strong effect with a cluster of flare spot peaks around 90° where the longitudinal panel and door edge joins produce effect.
In the narrow ±14.5° angular sector under the tail, the design will produce best effect against X/Ku/K/Ka-band missile seekers, but less useful effect against X-band engagement radars due to their higher power-aperture performance. At S-band the nozzle exterior signature will become increasingly prominent, leading to loss of effect in the vicinity of the L-band.
It is clear that these design choices were intentional and no accident. By confining proper stealth shaping technique only to the forward fuselage and inlet geometry, the designers avoided incurring the development, and to a lesser extent, the associated manufacturing costs of a fully stealthy design, with the YF-23A and F-22A presenting good comparisons.
This is an acceptable optimization if the intent is only to defeat an isolated individual low power aperture pop-up short/medium range mobile battlefield air defence system in the category of the SA-6 Gainful, SA-8 Gecko, SA-9 Gaskin, Chapparel, Crotale, Roland, SA-11 Gadfly, SA-15 Gauntlet, SA-19 Grison or SA-22 Greyhound. It is a completely unsuitable optimization for a wide range of other threat types which are in service, and the associated characteristic engagement geometries. It is also a problematic optimisation where short/medium range battlefield air defence systems are deployed in a coordinated manner.
The most generous description of the stealth design used in the Joint Strike Fighter is that it is 25% VLO, in the nose sector, 25% LO in the tail sector, and 50% reduced observable in the beam sectors, with a strong threat operating frequency and angular aspect dependency in stealth performance. It is clearly not a stealth design in the same sense as the F-117A Nighthawk, B-2A Spirit, YF-23A and F-22A Raptor, and to label it a VLO design is at best a quarter-truth, quite indifferent to the physical realities of the design and the threat systems it will need to defeat in future conflicts.
LM declares the RCS of F35 the size of "Golf ball size" (about 0.0015 m2) in 2000 (now it may be around 0.005m2, because LM has done lots of downgrading to reduce the cost).
Rafale Stealth Capabilities
Dassault reject the fourth-generation label and assert that, while Rafale fighter does not match the F-35's stealth, it can rival its effectiveness and survivability at a competitive cost.
To achieve this goal Dassault combine four factors:
RCS reduction of the most reflective parts of the structure
Development of passive detections
EW suite capable of jamming and decoying
Terrain following system
Development of passive detections and EW suite will be seen in the corresponding paragraphs in order to compare with F35.
RCS
The minimal RCS of Rafale, according to Dassault engineer (1/10~1/20 of Mirage-2000's frontal RCS), should be 0.05 to 0.1 m2 class.
Gripen was declared by Saab 1/5 of the frontal RCS of F/A-18 C/D, 1/3 of the frontal RCS of F-16 C/D block40/42, and 1/2 of the frontal RCS of the MIRAGE-2000". Or F-16 C/D block40/42 RCS is 1.2m2 which translate in 0.4m2 for Gripen, 0.8 m2 for MIRAGE-2000 and 0.08m2>Rafale>0.04m2.
The best estimate for Rafale seems to be 0.06 m2 with a max error of 0.02 m2. This is 10 times bigger than F 35 which gives a detection range roughly 2 times bigger for radar with the same performance.
Composite materials use
Rafale makes extensive use of radar-absorbent material (RAM) in the form of paints and other materials. RAM forms a saw-toothed pattern on the wing and canard trailing edges, for instance. The aircraft is designed to, so that its untreated radar signature is concentrated in a few strong "spikes," which are then suppressed by the selective use of RAM.
Rafale use a high amount of composite materials like you can see here:
Titane blue, Kelvar green, Composite Orange
In fact, 75% of Rafale surface structure and 30% of its mass are made of composites.
Besides, the high amount of composites and RAM materials, ducted air intakes, Rafale also has a sawtooth design feature all over the airframe and even in the air intakes. These sawtooth are made of RAM materials and meant to scatter and absorb radar waves:
All stealth fighters beginning with the F117 used similar sawtooth design features with the same aim of scattering the radar waves and to reduce the RCS.
Terrain following system
The Rafale is fitted with a multisensory terrain-following system operating at the pilot's choice from the radar or from a digital terrain database: the RBE2 radar can detect even unreported obstruction and the digital terrain database does away with telltale emissions where total covertness is required.
There is also a radar altimeter available in nap-of-the-earth flight over water or flat land. Data fusion is part of the system to cross-check the sensors before feeding their data to a flight path computation module whose development has been carried out per the exacting standards of safety-critical engineering.
The relevant expertise does not come overnight and actually builds on the lessons learned of the Mirage 2000N and D in service with the French Air Force.
The terrain-following function integrated with the Rafale's flight control system actually flies the aircraft closer to the ground or the sea than would be reasonable for the crew flying in manual mode - and it does so with a demonstrated safety level even in blind weather. Rafale is designed to fly a terrain-avoidance/threat- avoidance profile at 5.5 g and 100 feet in altitude. (
http://weapons.technology.youngester...of-set-of.html)
It remains a valuable help to the crew even when flying higher above ground level, allowing them to concentrate on other mission tasks without the burden -and energy consuming anxiety - of maintaining terrain clearance during hi-speed/low-altitude legs.
With its high thrust and low wing-loading, the Rafale is equally at ease flying at treetop height: its aerodynamics - delta wing and canards - is ideal for low-level agility and ride quality, and its canard fore-planes do not block downward visibility. Flying low and fast in the clouds then becomes a real option: high altitude SAMs are no longer an issue since you fly under the radar coverage, and short range optically-guided air defences are powerless against a foe they cannot see.
Other short range air defence systems can be dealt with by the Spectra EW suite capable of jamming and decoying. Speed is part of the game too, since air defence engagement zones are dramatically reduced against transonic targets, even in clear weather.
Source:
http://www.******************/forum...35-jsf-v-s-dassault-rafale.html#ixzz2eNt7gyla
Figures are in cluded in the original post.
