Passage: Although Brabham experimented with airdams and underbody skirts in the mid-1970s, the team, like the rest of the field, did not immediately understand Lotus's development of a ground effect car in 1977. The Brabham BT46B "Fan car" of 1978, generated enormous downforce with a fan, which sucked air from beneath the car, although its claimed use was for engine cooling. The car only raced once in the Formula One World Championship—Niki Lauda winning the 1978 Swedish Grand Prix—before a loophole in the regulations was closed by the FIA.Although in 1979 Murray was the first to use lightweight "carbon fibre composite" panels to stiffen Brabham's aluminium alloy monocoques, he echoed his predecessor Tauranac in being the last to switch to the new fully composite monocoques. Murray was reluctant to build the entire chassis from composite materials until he understood their behaviour in a crash, an understanding achieved in part through an instrumented crash test of a BT49 chassis. The team did not follow McLaren's 1981 MP4/1 with their own fully composite chassis until the "lowline" BT55 in 1986, the last team to do so. This technology is now used in all top level single seater racing cars.

Question: What is another name for Brabham BT46B?
Fan car