F-35B down.

[Engines]

Guys,

Thanks for the replies and comments. Hopefully, I can add some useful and occasionally interesting info on the F-35B STOVL flight controls here.

Going back to the start of the programme, the customers were very focussed on reducing through life cost and enhancing safety. The lessons of the USMC AV-8A fleet and the UK's Harrier experience were uppermost in their minds. They were also looking at reducing the pilot's flying workload as much as possible to allow him/her to focus on managing and winning in combat. They also wanted an aircraft that required less pilot training. These desires all came together in looking very hard at how to best control a STOVL aircraft in the transition, takeoff and landing.

These were crystallised out in the JORD in two ways. First, they demanded very good handling characteristics. secondly, they mandated that the flying controls that were operated by hand had to be limited to two 'inceptors'. The led to many studies and trials, and out of these came the F-35B system. I should note the huge contributions made by the BAE STOVL test pilots throughout the early years of the programme - their inputs, suggestions, criticisms and teamwork laid the foundation for what the team has achieved. A special mention should also go to the pioneering VAAC Harrier test bed, designed at Cranfield and put to hard work at Boscombe and also at sea, helping to develop the new STOVL flight control laws. It should be understood that two of the highest risk areas of the F-35 development programme were the integration of the STOVL propulsion system with the airframe, and the development of the STOVL flight control laws and flight control system. Both of these were led and executed by BAE Systems. Personally, I don't think they get anywhere near the amount of credit they are due.

The end result is a 'powered flight mode', which the pilot selects by a single action switch on the left hand 'inceptor'. This initiates the change from fully wing borne flight, and it can be selected over quite a wide speed range. In this mode, as I've posted earlier, the controls change from a 'throttle' (more like an energy demand) and 'stick' (more of a flight path demand) to a 'fore and aft rate' demand via the left hand inceptor, and a vertical rate and lateral rate demand via the right hand inceptor. This was a very controversial decision at the time, but was supported by extensive work in both conventional sims and the vertical motion simulator at NASA Ames, I believe. One aspect of this new flight control system is that the pitch of the aircraft is not controlled by the pilot.

However, the transition from 'normal wing borne' to 'full stop powered lift' is managed via an automated 'blend' programme which, I understand, is mainly driven by aircraft airspeed. So, the excellent pictures Gums posted up very probably (alert - I'm now assuming stuff) show an F-35B in the high speed end of the 'powered lift' mode. The landing gear is still up (this is selected independently from the powered lift mode selection), the lift fan door is in the 30 degree position for higher speeds, and the 3BSM is down at around 10 to 15 degrees or so. All the various doors are opened at this stage, except the inner weapon bay doors that deploy automatically just before touch down. In the powered lift mode, thrust can be moved between the front lift fan and the aft nozzle - it's not a fixed 50/50 spilt. So, in these pics, the lift fan IGVs will have shut down, reducing the power demand from the fan, and allowing more 'grunt' to come out of the rear.

Gums is spot on - the result is that landing the F-35B on the boat is several orders of magnitude easier than it was for the Harrier folk.

Best Regards as ever to our excellent people who continue to bring the jet to the front line. If it wasn't hard it wasn't worth doing....

Engines