Mainly announced as to extend the recce ability beyond the max operating height of the Valiant but as usual there were other political, economic and operational drivers at work also.

There were other parallel roles for Valiant/Canberra eg ECM and Signal Intel so it seems that one role /one airframe was not an economic limit for the airships of the day.

Hindsight shows the logic paid off with other operational assets being in place to take up tasking when a type failed in a role or change of operating conditions.

Canberra had been a very lucrative airframe for English Electric (some airframes going on being sold at least three times to different air forces in their life) and the BI(8) being was well looked on for it’s RAF service (prior to 1959 when design study P28 was produced by Warton). This meant that the internal development costs of the B(I)8 for a more powerful low level interdictor airframe could be viewed with potential upgrade sales to the RAF and other air forces.

P28 looked to improve the BI(8) penetration speed, range at low level and low level stability for fatigue improvement both of pilot and airframe. All features that would come to favour the PR.9 remaining as the recce platform when the V force changed from high level to low level.

The airframe produced had power operated controls to give quick, accurate control response and the combination of wing loading/ ratio of tare to all up loading/engine power all resulted in an airframe that was stated in the glossy catalogue as 50,000ft + but in reality was 60,000ft+.

This fitted the need for an additional high level strategic recce airframe for the RAF and was offered with a lower development cost burden than the other crescent/delta airframes being considered.

For the politicians the use of Shorts in Belfast to produce the licence built examples was an attractive hook and EE would not have to divert mainland factory production space from production of other types.

I think that Wyton was used as the into service location due to the presence of the photo “moles” ground staff to process the film rather than role supplement of Valiant.

The PR.9 was quite quickly moved from the UK to Malta with war bases intended in Turkey giving a strategic operating role divorced from the remaining Valiant PR fleet.

The initial operating height of 60,000+ was achieved by crew partial pressure suits/helmets and uprated oxygen regs. When Typhoon was initially being trialled in service at these heights Safety Section at Marham re-lifed a few of the 1960s high altitude kit for development use before the bespoke airframe specific kit had arrived.

Regards
Ross