WE CLAIM:
1. A gas turbine engine (100) comprising:
a core (102);
a variable pitch fan (104) arranged in flow communication with said core, said
variable pitch fan comprising a disk (112) and at least nine fan blades (110) coupled
to said disk for rotation together with said disk; and
a rotatable nacelle (120) covering said disk such that said engine has a fan hub
radius ratio of between about .1 and about .4.
2. A gas turbine engine (100) as claimed in Claim 1, wherein said fan
(104) comprises at least fifteen fan blades (110).
3. A gas turbine engine (100) as claimed in Claim 1, wherein said fan
(104) comprises at least twelve fan blades (110).
4. A gas turbine engine (100) as claimed in Claim 3, wherein said fan
hub radius ratio is between about .2 and about .35.
5. A gas turbine engine (100) as claimed in Claim 3, wherein said fan
hub radius ratio is between about .2 and about .3.
6. A gas turbine engine (100) as claimed in Claim 1, comprising a
trunnion mechanism (142) coupling each of said fan blades (110) to said disk (112)
such that said fan blades (110) are rotatable relative to said disk about a pitch axis
(114), wherein each of said trunnion mechanisms comprises a line contact bearing
(146, 162).
7. A gas turbine engine (100) as claimed in Claim 6, wherein said
trunnion mechanism (142) comprises a first line contact bearing (146) and a second
12
line contact bearing (162), wherein said first line contact bearing is oriented at a
different angle than said second line contact bearing relative to the pitch axis (114).
8. A gas turbine engine (100) as claimed in Claim 1, comprising:
an actuation mechanism (116) for varying a pitch of said fan blades (110); and
a pitch correction device operatively coupled to said fan blades via said
actuation mechanism.
9. A gas turbine engine (100) as claimed in Claim 8, wherein said pitch
correction device is one of a remote counterweight device (122) and a remote pitch
lock device.
10. A gas turbine engine (100) as claimed in Claim 1, comprising a fan
cowl (124) surrounding said fan (104) to form a bypass duct (126).