This is part of a flight test article in the BMAA magazine.
At the core of the problem was longitudinal
stability. Broadly speaking, it’s regarded as a
good thing if the more you pull (or push) the
stick from the trim position, (a) the faster (or
slower) the aircraft goes, and (b) the larger the
forces are. The Savannah was fine at doing the
first, but there weren’t enough centring forces,
and a low-hours pilot could accidentally apply
lots of up or down stick without realising it.
BMAA test pilot Tim Cripps spent a long time
getting the figures for all this, and helping to
devise a simple get-around that didn’t involve
too much modification.
The simple fix may not look too elegant,
but it works and, since it involves a length of
bungee and a jamming cleat, Thruster owners
will feel right at home!
Anyway, finally the modifications were
sorted out, so now we can go and fly