The CYRANO "saga" began in 1958, after the choice of the MIRAGE III from Avions Marcel Dassault as the weapon aircraft of the French Air Force. These aircraft were to be equipped with a state-of-the-art forward radar and Marcel Dassault, whose electronics department under department under the direction of Bertrand Daugny had designed an airborne radar for light interceptors, the
Marcel Dassault, whose electronics department under the direction of Bertrand Daugny had designed an airborne radar for light interceptors, the "Super ALADIN", questioned CSF's ability to produce a radar of this type.
CSF decided to take up the challenge and promised a ground demonstration within six months of a monopulse radar model compatible with the MIRAGE IIIC. This was a world first, as the competing radars used much less efficient scanning tracking. [translator note: incorrect - Ferranti AI.23 was designed before this)
G. Le Parquier's mission was to convince a state commission of the interest of a monopulse antenna and a very original firing calculator... without giving too much information likely to benefit the competition!
But the CSF model was still not very advanced and, as no risk could be taken, it was the classic solution with a scanning antenna proposed by Dassault that was chosen at first.
Fortunately, for CSF, the events in Algeria in 1958 "froze" this first decision and, in mid-July, it was possible to present again its model, which surprised by its performance and called into question the initial choice.
This is how the following contracts were awarded successively in October 1958 and within a fortnight of each other. The conditions were draconian: the deadline was set for the development of the prototype, which was to be completed by the end of the year, and the contract was to be signed by the end of the year. The conditions were draconian: one year for the prototype, two years for the pre-series and 27 months for the 3 of the first production run, with a ramp-up to one radar every two working days. Penalties were doubled for delays.
Three CYRANO I prototypes were built to evaluate the weapon system, subsequently 8 pre-production CYRANO I bis radars were added to ensure this evaluation. Then the production was started first with the CYRANO I bis for MIRAGE III C and soon after with the CYRANO II for MIRAGE III E.
Cyrano 1 bis radar for Mirage III C (1958) - Courtesy of THALES
Cyrano in Mirage IIIC (Aviation Week, July 23 1962)
The main characteristics of the CYRANO I bis, which was produced in 223 units from 1958 onwards, under the direction of 1958, under the direction of A. Perato, are the following:
Pressurised front end due to the high voltages (class 10kV) of the transmitter).
Circuits cooled by water/glycol circulation (later FHS).
Monopulse antenna of 36 cm diameter, orientable in the field with formation of channels by guides on the mobile part and the channel formation by guides on the mobile part and 3 rotating joints on the guide.
300 kW peak transmitter (4 J 50 magnetron) in "X" band (λ = 3cm).
Receiver with a noise factor of 9 dB, with mixers and preamplifiers on the moving part and power supply by mobile "flexible" strand.
The technological evolutions of the CYRANO II, which was produced in 635 copies from 1964, are mainly due to the choice of a "Cassegrain" antenna which ensures a better performance.
However, it was the MIRAGE III E version that was a remarkable achievement for its time.
It allowed the following air-ground functions to be carried out:
Ground mapping: a ground map is presented on the indicator in PPI mode (bearing-distance). The ground map is refined by using monopulse deviation measurements. The pilot has control over the antenna scan and can illuminate particular areas.
Iso-altitude cutting or "contour mapping": only echoes located above a horizontal guard plane are presented. The pilot can thus bypass the obstacles appearing on the screen.
Blind breakthrough: the function is identical to the previous one, but the guard plane is no longer horizontal but parallel to the aircraft speed vector.
Anti-collision: identical function, but the last third of the guard plane is curved upwards to ensure safety.
Air-to-ground telemetry for AS30 missile firing: the antenna is then fixed in the aircraft axis
Described as Cyrano IV, this picture from Wikimedia seems to me to be Cyrano II.
With the development of the MIRAGE F1, it was the turn of the CYRANO III prototypes, then the CYRANO IV series radars produced from 1972. Still based on a magnetron emitter, their development was based on several factors:
New “inverted Cassegrain” antenna with very high mobility, with a carried diameter at 57 centimeters to improve the range of the radar.
Transistorisation of reception and processing circuits, with “bundle” assemblies to reduce the volume occupied by these circuits.
Modular design of transmission reception units, set up for the version modernized CYRANO IV M, and which served as a standard for further developments.
Mirage F1 Radar Cyrano IV (1972) - Courtesy of THALES
850 CYRANO IV and CYRANO IV M were in turn produced both for France and for export, which had been the engine of their development.
Cyrano 500 (a low PRF pulse doppler radar roughly equivalent to AWG-10) was renamed RDM (See here)
The airborne fire control radar CYRANO IV is an integral part of the navigation and weapon system (NWS) fitted on high performance single seater interceptor fighters MIRAGE F1.
This radar was essentially designed to afford the following to the carrier aircraft :
- interception of enemy aircraft at all altitudes by means of guns and missiles,
- Air-to-Ground intervention (tactical support) by visualization of the land forward of the aircraft.
- gun emergency firing (range finder).
The interconnections between the radar CYRANO IV and the other NWS elements are illustrated by figure 1-1. The radar and NWS elements which are directly connected are indicated by a letter :
A - Weapon selector
BA - Radar display unit CRT unit
CA - Nose cone
D - Gyro unit
EA - Radar filter
F - Data link receiver
GA - Antenna program accessory unit No 1.
HA - Antenna program accessory unit No 2.
i - Gunsight
KA - Radar display unit circuits unit
LA - Radar display unit control box
MA - Radar stick
O - Autopilot
P - MATRA harmonization unit
R - Air data unit
T - Incidence indicator
VA - AMTI UNIT
ZA - Accelerometer
Several controls are used to start and operate the radar; the data are grouped on the CRT unit, BA, the gunsight I, and the navigation indicator.
The main radar controls are located on the following elements :
the radar stick MA (fig. 2-7) located on the LH console of the cockpit,
the CRT unit BA. (fig. 2-5) located at the right of the instruments panel,
the control box LA. (fig.2-6) located on the RH console of the cockpit,
the weapon selector LA located on the RH console of the cockpit and which also comprises the radar starting control,
the GUN EMERGENCY control located on the throttle handle.
The radar receives :
from the aircraft mains system, the AC and DC voltages necessary to its operation,
from an engine pressure pick-off, P0, compressed air for the nose pressurization,
from a heat exchanger, a cooled fluid for the nose cone cooling,
from the air data unit, the speed, altitude and pressure data,
from the gyro unit, the roll and pitch data,
from the indicator, the sine i and cosine i data,
from the data link, the azimuth and the distance of the enemy.
The weapon selector imposes the suitable operating mode for the mission to the radar.
2 - INTERCEPTION MISSION.
This type of mission allows interception of enemy aircraft detected by the ground installations. The figure 1-2 illustrates the radar operation diagram for this type of mission ; there are ten distinct sections :
the power supplies,
the antenna,
the UHF circuits,
the modulator transmitter,
the receiver,
the tracking error ranging,
the servo-mechanisms,
the interception computer,
the firing zone computer,
the display unit.
The interception mission can be divided in four phases :
the "search" phase during which the target position Is conveyed to the pilot through radio, or to the radar by data linking, and which leads to the target detection.
the "lock-on" or acquisition phase which consists in selecting the target in distance and direction, and in slaving the radar to track the target.
the "automatic tracking" phase which, taking info account the armament characteristics, the aircraft possibilities and the target flight characteristics, brings the aircraft in an ideal firing position where the target destruction probabilities are maximum.
the evolution phase after firing which allows the aircraft to break-off safety.
The overall operation is as follows :
the power supplies receive the 27 V DC and the 200 V - 400 Hz three-phase voltages from the aircraft mains. They supply the radar with a DC and AC voltages necessary to the operation.
the modulator transmitter, controlled by a synchronization circuit coming from the ranging system, supplies UHF pulses to the antenna through the UHF circuits which comprises, in particular, a roll rotating Joint and a dupiexer,
the antenna is controlled by the servo-mechanisms which are themselves controlled by the radar stick.
at reception, the energy reflected by the target is collected by the antenna, then is sent through the dupiexer to mixers which, by means of the local oscillator, perform a frequency shift.
the "IF" intermediate frequency wave is amplified and then detected by the receiver which supplies video frequency signals directed to fhe tracking error ranging circuits.
after processing in these circuits, a video frequency signal is sent to the display unit.
2.1 - Search phase.
During the search phase, all the signals received by the antenna appear on the display unit. According to the accuracy of the data conveyed by the ground installation, the pilot selects an appropriate antenna scan by means of the radar stick :
60° scan,
30° scan,
elliptic scan.
60° scan.
When the data is not very accurate, the zone scanned by the radar should be large, in this scanning mode, the radio-electrical antenna beam scans a 120° sector in elevation, centered on the aircraft centerline at an elevation angle displayed by means of the radar stick. The radar display unit informs the pilot about the received signals (direction and range), and a strobe, controlled in range and direction by the radar stick, and shown on the radar display unit. Indicates the direction and range where lock-on is possible.
30° scan.
In this scanning mode, the zone scanned by the radar is smaller than the preceding one and the data conveyed by the ground installation should be more accurate. The antenna radio-electrical beam scans a 60° sector in elevation, centered on a direction defined in elevation, bearing and range by the radar stick (direction and range correspond to the data conveyed by the ground Installation).
Elliptic scan.
This scanning mode Is used when the target position is known accurately. This position is conveyed to the pilot by radio, or directly to the radar, by the data link receiver. The antenna radio-electrical beam performs an elliptic scan of 14° in bearing and 4° in elevation, around this direction.
A control, located on the radar display unit CRT unit enables matching the radar operation with the density of the ground echoes received by the antenna ; High Altitude, Short Pulse, Medium Altitude, Low Altitude. The High Altitude operation mode will be used when there is no ground echoes, or that the latter are not disturbing. It authorizes the three search procedures mentioned hereabove and enables, in the best conditions, locking-on the radar onto a target located at 35 NM. When the ground echoes prevent the target identification, the short pulse operation permits to attenuate their importance, but limits the radar range.
If the target identification is impossible in short pulse, the medium altitude operation will be used. The radar range Is then widely limited and, in addition, the search mode in elliptic scan, with or without data link is prohibited.
When the aircraft flight altitude is lower than 6.000 metres, the low altitude operation puts into a service a coherent automatic moving target intensifying device enabling the Interception of a moving target flying at low altitude.
2.2 - Lock-on phase.
When the target echo is spotted, the pilot brings the RH edge of the strobe in coincidence with the echo, by means of the radar stick, which sets the mean direction in the target direction and the ranging at the target distance.
During the lock-on authorization, the scanning stops and the antenna radio-electrical beam is placed in the mean direction, therefore in the target direction.
The tracking error ranging is servo-controlled to track the target echo in range, and delivers target aim-off data with respect to the antenna beam axis. These data control the servo-mechanisms and the antenna beam remains permanently aimed in target direction. The radar Is therefore slaved to the target.
2.3 - Automatic tracking phase.
Now the aircraft should be piloted so as to bring it closer to the target and to place it in an ideal firing position; this is the function of the interception and firing zone computers.
The servo-mechanisms deliver direction and shift speed of the antenna beam, therefore of the targe These data and those delivered by the ranging function (range,radial velocity) are processed, taking info account the selected weapons, by the Interception computer which delivers piloting orders R and T, represented by the gunsight. These piloting orders, carried out by the pilot, make the aircraft describe an approach path, placing It in the ideal firing conditions.
In a parallel manner, the firing zone computer, taking into account the flight characteristics of the aircraft and target, and the possibilities of the selected missile, computes at any instant, the path that should be followed by the missile, and determines the firing limits (minimum, optimum, maximum distances, firing angle ...). These limits, compared with the fighter posi-tion with respect to the target, lead to the missile firing, either automatically or upon an order given to the pilot by the gunsight.
2.4 - Manoeuver phase after firing.
To be self-guided onto the target, some missiles require the electromagnetic radiation of the radar reflected by the target. The interception computer determines the path that should be followed by the aircraft in order that the target be permanently illuminated. In the same time, the firing zone computer determines the missile-target collision instant, instant when the air-craft should mandatorily break-off so as to avoid being hit by the target or missile splinters in a path given by the interception computer and represented by the gunsight under form of orders.
3 - GUN EMERGENCY CONTROL FIRING.
This operation mode permits the rapid lock-on of the radar onto a target located before the air-craft at a distance lower than 6 NM, for the gun firing, it is obtained by depressing the gun emergency control button located on the throttle handle. This operation mode has priority upon the interception mission during the search phase and upon the air-to-ground intervention mission.
The operation diagram of the radar in this operation mode is shown on figure 1-3 ; the same parts as In interception mission can be seen, but the radar stick is not used.
The gun emergency control firing mission is divided into three phases :
the search phase during which the radar automatically searches a target in a 6 NM zone before the aircraft ;
the lock-on phase during which the radar automatically !ocks-on the first encountered target ;
the automatic tracking phase which brings the aircraft at a distance from the target where the guns can be used.
The operation is the following :
During transmission, the operation is identical with that of the Interception mission.
3.1 - Search phase.
As soon as the gun emergency control firing mission Is selected on the gas throttle, the antenna performs a 4° diameter circular scanning around the aircraft centerline. The echoes received by the antenna and located at a distance lower than 6 NM appear on the radar display unit. In the same time, the ranging performs a range scan from 0 to 6 NM.
3.2 - Lock-on phase.
As soon as ranging encounters an echo, the radar locks-on onto it in range and direction. The antenna scan stops and the antenna is controlled by the tracking error ranging signals ; the antenna beam remains permanently aimed In the target direction.
3.3 - Automatic tracking phase.
The target direction, speed and distance delivered by the servomechanisms and the tracking error ranging are fed to the interception computer which delivers piloting orders AR and AT, represented by the gunsight and enabling to place the aircraft in the ideal gun firing conditions.
The firing zone computer is not used except when the weapon selector is on position MATRA MAGIC 550 : in this case, the computer determines the firing limits of this missile and conveys them to the pilot through the gunsight.
4 - AIR-TO-GROUND INTERCEPTION MISSION.
in this mission, the display unit displays the radar map of the ground flown over forward of the aircraft. The operation diagram of the radar is shown on figure 1-4 ; the same parts as in inter-ception mission can be observed, except the interception and firing zone computers which are not used.
The operation in transmission configuration is identical with that of the interception function. During reception, the gain can be adjusted by means of the radar stick. The video signals obtained on the receiver output are processed by the ranging circuits, then represented by the display unit in PPI off-centered scanning. Four range representation scales, selected on the radar stick are at the pilot's disposal : 7 NM, 15 NM, 35 NM and 60 NM.
The antenna is scan controlled by the servomechanisms. The mean position in bearing is null and the antenna radio-electrical beam scans a 120° or 60° sector in bearing, centered on the aircraft centerline. The elevation is computed in function of the aircraft flight altitude and can be modified by means of the radar stick to illuminate at best the flown over ground zone and obtain an accurate representation on the radar display unit.
Been looking for a pic of the Cyrano in the III-C for a long time. I never knew its official 'name' was Cyrano I bis.
I seem to remember teaching that it emitted 200KW pulse power, rather than 300KW, but that was many decades ago, so perhaps I forget.
Thank you. Reminds one of good times.
Interesting question. I'd say France was slightly ahead, but the Cyrano IV MTI lookdown modes never worked, unlike Sapfir-23 whose lookdown modes eventually became useful.
French radars were more all-round capable with mapping and air-to-ground functions and from 1987 you'd probably pick RDI over N019 I think.
Interesting question. I'd say France was slightly ahead, but the Cyrano IV MTI lookdown modes never worked, unlike Sapfir-23 whose lookdown modes eventually became useful.
French radars were more all-round capable with mapping and air-to-ground functions and from 1987 you'd probably pick RDI over N019 I think.
According to this article, the Cyrano-IV weighs 250kg, has a practical range of 70km vs large aircraft like a transport, and can detect a fighter at 55km and track at 40km.
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