Looking at the pic of the Lightning, what was the goal of the engineers loading the engines on top of one another?
Was accessing the engines for MX easy with this configuration?
Obviously the thrust line is close enough, but was there any pitch asymmetry if one engine was out?
I think we're now into thread drift re. the original question.
Bill Petter, not the engineers, reasoned that it would reduce frontal area and he didn't go with area ruling. The No.2 engine (upper) was staggered aft of the No.1 to achieve a satisfactory C of G envelope. Engine changes were not easy, but then again as others have said, nothing was easy on the Lightning (except flying it).
The aeroplane did not exhibit any noticeable assymetric pitch with one out. Astonishing is the fact that it could achieve a rate of climb of around 20,000 feet per minute in burner
on one.
However, axial flow Avons seemed to cope admirably with this diet and I have no doubt vulcanic ash would have been equally acceptable!
Avons would cope with anything except fires.