Let me assume the role of my signature as 'Purveyor of Egg Liqueur to Lucifer' and look at the possibility of a bird strike in the fenestron.
As we all know when driving, birds occasionally have a suicidal tendency to fly in front of vehicles, not only across country roads but also larger roads and motorways, day and night. Very very rarely do they impact the side of the vehicle, as they either just make it, apply an amazing avoiding manoeuvre, or somehow make it below the vehicle amazingly dodging the wheels. rarely rarely do flying birds get run over, let along fly into an open window.
I would like to use the the analogy of the open rear window and the fenestron, when this possibility of a bird strike on the fenestron is raised.
The front and rear windows of a Land Rover Discovery are 50cm x50cm and the radius of the 135 fenestron shroud is 50cm, with the cap 18cm in radius. (I have both car & cab in front of me now)
The area of one window is 2,500cm squared.
The total area of windows on each side is 5,000cm squared.
The area of the shroud is 7,854cm squared.
The area of the fenestron cap is 1,018cm squared.
The total area of the exposed fenestron blades on each side is 6,836cm squared.
(I shall ignore the drive shaft cover on the port side, with an area of 306cm squared)
The difference in area between the open windows and fenestron blades is 1,836cm squared, a difference in size that is equal to the front, rear and luggage compartment windows of the Discovery.
Of course we need this to be in a single area as opposed to a series of windows along the length of the Discovery. As it happens, the area is equivalent in size to the back door on the Discovery, allowing for the wheel arch shaping.
What believers of the bird in the fenestron theory want us to accept, is that if you are driving down a motorway at 70 mph in the Discovery with a rear door removed, a bird could fly into to the car through the open space left by the door.
Adding in to the equation the linear speed trigonometry involved, the donut shape of the fenestron, the downforce of air holding up a 2.5 tonne helicopter and the forward 45 degree sector being blocked by the vertical & horizontal stabilisers .......
... I'm not saying that the bird flying into the fenestron theory is impossible, just that it's highly improbable.