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By: 1st October 2014 at 01:10 Permalink - Edited 1st January 1970 at 01:00
-From what I gather the Aboukir created a lot less drag in combat conditions.
By: 1st October 2014 at 09:41 Permalink - Edited 1st January 1970 at 01:00
-That's the story - but was this ever tested/proven? Is there any evidence? Even any specific anecdotes other than a general "Well they did it so it must be better"?
By: 1st October 2014 at 14:46 Permalink - Edited 1st January 1970 at 01:00
-copied from another forum
Quoted from Morgan and Shacklady's Spitfire book. This all they have written up about the Aboukir filter
"The large Vokes tropical intake was not well liked by the services and it was not long before unofficial modifications began to appear, the most successful and designed and installed by that most resourceful team at No. 103 MU Aboukir. They trimmed the filter back to a much smaller unit, one that was more efficient and drag reducing. It was named the Aboukir filter and the Vokes Aero-Vee, fitted to the Mark IX Spitfire, was based upon this local modification. Supermarine was quick to appreciate the lower drag of the modified intake and they tested a number of hand-built units on two VC's and a Seafire Mk. II. The test comprised speed runs with the normal temperate intake, the normal tropical and Aboukir. The VC's were EF541 and JK940 and Seafire NM977, the former with Merlin 45's and de Havilland hydromatic propellors, the latter with Merlin 46's and Rotol Jablo. The new type of cowling was infinitely better of the three tested and there was a weight reduction of 20 pounds. Another bonus was that with the filter element removed the Aboukir could be used as a normal temperature intake."
By: 1st October 2014 at 17:16 Permalink - Edited 1st January 1970 at 01:00
-That's a good step forward, although the term "infinitely better" is garbage and not something any engineer would say. Perhaps they just meant "definitely". It still says nothing about the how and why.
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By: Graham Boak - 29th September 2014 at 12:02
Does anyone know why the Aboukir filter should be any better than the Vokes one? Both rely on passing the air through a convoluted filter, which removes any of the pressure recovery that could have been expected from a well-designed intake. The Vokes has greater surface area, hence more skin friction drag, but the Aboukir is shorter and squatter which makes for more profile drag. Swings and roundabouts, it would seem. Was the Aboukir filter actually proven better, or was it one of those "invented here therefore must be better" sort of things?