Originally Posted by
BEagle
Westlands used to have a site at RAF Merryfield (it's now an official gypsy site); nearby were a couple of tunnels under the concrete hardstanding with large 90° ducts at one end, venting to atmosphere at the other. As a small boy, once the RN's Sea Venoms had returned to Yeovilton and the aerodrome virtually abandoned, I explored the tunnels wondering what they'd been used for. Doubtless the def-jet Meteor was positioned over them to test the installation. Pictures exist of RA490 at what is clearly Merryfield (there's a particular type of tree in the background which I well remember!), but I think that the aircraft was flown to RAF Farnborough for trials work, also at RAE Bedford.
safetypee, you had the best answer, so over to you!
During the period some undergrowth at Farnborough was being cleared (c 1995 to 2001) next to the area known as 'the dump' where various aircraft were 'dismantled', some sort of deflector or attenuator was exposed buried in the ground; it appeared to exhaust downwards and the efflux came out from a sort of culvert below ground level a few feet away.