747 lack of Mach Trim
Meikleour, 747 lack of Mach Trim.
D Davis provides good reasoning in 'Handling the Big Jets' (3rd edition).
The design of the 747 trim system provisioned Mach Trim, but it was not fitted for certification. It is not clear if the deletion was a pre first-flight design decision or as the result of early flight testing.
Davis describes the 747 as having good longitudinal stability and control; large control surfaces and good trim characteristics.
The stick force gradient at high speed was low, but did not reverse. Although these characteristics did not meet 'the letter' of BCARs ( assume that they did meet the differing FAR ), it was accepted for UK certification - judgement call. Noting that the VC10 and Trident had similar characteristics, but did have Mach Trim fitted.
From the narrative I suspect that the lack of 747 'Mach Trim' was a compromise in relation to the more emotive CAA/FAA discussions on stick nudgers / stick push in that era.
Last edited by safetypee; 19th Jun 2020 at 17:50.
Reason: Typo