Obstacle and terrain warning radar system for a rotorcraft
View Patent ↗Obstacle and terrain warning radar system ( 1 ) for a rotorcraft ( 2 ), the system having at least two assemblies ( 10 ), each having at least one radar unit, said rotorcraft ( 2 ) including at least one main rotor ( 20 ) having at least two blades ( 22 ) and a rotor head ( 23 ). Each radar unit transmits a centrifugal radar beam ( 17 ) with angular beam width in azimuth α of at least 5° and beam width in elevation ε of at least 5°. Said assemblies ( 10 ) of at least one radar unit are positioned directly on said rotor head ( 23 ) between said blades ( 22 ), said radar system ( 1 ) electronically scanning the surroundings with angular coverage in elevation of at least +/−15° and mechanically scanning the surroundings with angular coverage in azimuth of 360°, and then informing the pilot of said rotorcraft ( 2 ).
1. An obstacle and terrain warning radar system for a rotorcraft, the system having a plurality of radar units, said rotorcraft having at least one main rotor with an axis of rotation, at least two blades, and a rotor head, each radar unit transmitting a radar beam with a beam width in azimuth α of at least 5° and a beam width in elevation ε of at least 5°, the elevation direction being along said axis of rotation of said main rotor, and a zone scanned in azimuth by said radar beam being in a plane perpendicular to said axis of rotation, the radar system comprising at least two assemblies positioned and fixed mounted in a regular manner around said axis of rotation directly on said rotor head between said blades, each assembly having at least one radar unit, each radar unit transmitting a centrifugal radar beam, said radar system scanning the surroundings around said rotorcraft electronically in elevation with an angular coverage of at least +/−15° and automatically in azimuth with an angular coverage of 360° during the rotation of the said main rotor.
2. A radar system according to claim 1 , wherein said radar system has at least as many assemblies as there are rotor blades on the rotorcraft.
3. A radar system according to claim 1 , wherein each assembly has at least two radar units positioned side by side around said axis of rotation of said main rotor.
4. A radar system according to claim 3 , wherein two centrifugal radar beams from two adjacent radar units are separated by an angle 11 about said axis of rotation, in azimuth, of at least 1°.
5. A radar system according to claim 1 , wherein said main rotor has a number nr of blades, and a total number k of radar units required is given by a formula:
k=nr·q,
where “q” is a coefficient such that:
nr
≤
q
≤
360
°
nr
·
(
α
+
η
)
,
“α” being an angular coverage in azimuth of each radar unit, “η” being an angle separating two radar beams of two radar units that are adjacent in azimuth and “·” being a symbol of a multiplication.
6. A radar system according to claim 1 , wherein said radar system comprises a control and synchronization unit to supply control and synchronization information needed for each radar unit, an evaluation unit to evaluate data provided by each radar unit and to calculate positions of any obstacles and terrain relative to the said rotorcraft, an information transfer unit to transfer information between moving elements of the radar system and fixed elements of the radar system, a power transmission unit to provide electrical power, and an obstacle and terrain warning instrument to indicate positions of these obstacles and terrain on at least on display mean.
7. A radar system according to claim 1 , wherein said radar system scans surroundings with an angular coverage in elevation of at least +/−30°.
8. A radar system according to claim 1 , wherein said radar system scans surroundings with an angular coverage in elevation of at least +/−60°.