Just curious if there is any definitive test document for the 460mph maximum speed often quoted for this plane (noting some skepticism expressed here), or if it is just an estimate? Also on whether it had any stressed skin construction?
I took some extracts from chapter 21 of British Experimental Combat Aircraft of World War II by Tony Buttler (2012) on the Internet Archive (unfortunately down atm), and it seems like information is pretty sketchy:
R2496 went to A&AEE again on 15 April and flight trials were completed on 21 May, and on 17 April AVM John Boothman flew it while on a visit to Boscombe. After his single flight he was able to report that it was: "...quite an outstanding aircraft in so far as control and Stability are concerned. I have seldom flown an aircraft which combines the positive stability of the American fighter with the extreme manoeuvrability usually associated with ours." Boothman added that the top speed was about the same as the Hawker Tempest and Spitfire Mk.XXIIl [sic], but thought that its climb was somewhat down on both of these aircraft.
On 24 July 1946 A&AEE issued a flight test report on the M.B.5, although since the type would not be entering production an extensive trial was thought unnecessary. ...
Overall the report concluded that, in general, the M.B.5 was easy and pleasant to fly and was highly rated by all who flew it in regard to its flying qualities. It was felt that its combination of steady flight behaviour, good control and excellent pilot view should make the M.B.5 a very good gun platform. However, against present standards the aircraft's performance was described as disappointing and it was felt that it was underpowered. This opinion was based on the result of poor acceleration and a low rate of climb. However the maximum level speed performance could not be checked because of insufficient engine cooling which restricted the power available. That criticism of the performance surprised this author since so many reports relating to the M.B.5 have praised its speed so highly, quoting a maximum of 460mph (740km/h) at 20,000ft (6,096m) which was exceeded in the UK most probably only by the Napier Sabre-powered Hawker Fury prototype, by the Supermarine Spiteful (Chapter Thirty-Two) and by the twin-engined de Havilland Hornet prototypes.
On construction:
The airframe used the serial R2496 which indicates that it was the second M.B.3 modified or rebuilt. Indeed, in many respects Martin-Baker designs were 'Meccano kits' and for the M.B.5 it is understood that the pilot's cockpit was just moved to a different pair of frames within the fuselage.
[Chapter 20] The experience gained in manufacturing the M.B.1 and M.B.2 was carried over to the M.B.3 but, whilst retaining the essential characteristics of the earlier designs with a fuselage primary structure built in steel tubing, the new aircraft introduced many new features. Metal stressed-skin panels with flush riveting replaced all of the fabric covering ...
[Chapter 19 on M.B.2] The wing had a triangular spar (a single spar built up of steel tubular members) and was fabric covered aft of the spar (as was the rear fuselage), but the forward fuselage and wing were covered by easily removable metal skin panels.
I have seen many contradictory opinions online, usually without sources. There seems to be general agreement the plane used a Griffon 83 with something like 2,340hp (though British Secret Projects says 2,305hp and Wiki 2,035hp).
On the construction, I am assuming the removable panels do not count as stressed skin (the attachment points are too few/loose to add structural strength?) but at least according to Buttler they do not cover the whole surface so the rear wings and fuselage could still be stressed skin.
I note Old Machine Press gives the Buttler book as its newest source, although it also gives the usual 460mph without stating the source, and adds "Some sources state the MB5 was prepared for a speed run in the fall of 1945. The Griffon engine was boosted to produce 2,480 hp (1,849 kW), and the aircraft reached 484 mph (779 km/h) on a measured course near Gloucester. However, the speed record claim seems highly doubtful."
I took some extracts from chapter 21 of British Experimental Combat Aircraft of World War II by Tony Buttler (2012) on the Internet Archive (unfortunately down atm), and it seems like information is pretty sketchy:
R2496 went to A&AEE again on 15 April and flight trials were completed on 21 May, and on 17 April AVM John Boothman flew it while on a visit to Boscombe. After his single flight he was able to report that it was: "...quite an outstanding aircraft in so far as control and Stability are concerned. I have seldom flown an aircraft which combines the positive stability of the American fighter with the extreme manoeuvrability usually associated with ours." Boothman added that the top speed was about the same as the Hawker Tempest and Spitfire Mk.XXIIl [sic], but thought that its climb was somewhat down on both of these aircraft.
On 24 July 1946 A&AEE issued a flight test report on the M.B.5, although since the type would not be entering production an extensive trial was thought unnecessary. ...
Overall the report concluded that, in general, the M.B.5 was easy and pleasant to fly and was highly rated by all who flew it in regard to its flying qualities. It was felt that its combination of steady flight behaviour, good control and excellent pilot view should make the M.B.5 a very good gun platform. However, against present standards the aircraft's performance was described as disappointing and it was felt that it was underpowered. This opinion was based on the result of poor acceleration and a low rate of climb. However the maximum level speed performance could not be checked because of insufficient engine cooling which restricted the power available. That criticism of the performance surprised this author since so many reports relating to the M.B.5 have praised its speed so highly, quoting a maximum of 460mph (740km/h) at 20,000ft (6,096m) which was exceeded in the UK most probably only by the Napier Sabre-powered Hawker Fury prototype, by the Supermarine Spiteful (Chapter Thirty-Two) and by the twin-engined de Havilland Hornet prototypes.
On construction:
The airframe used the serial R2496 which indicates that it was the second M.B.3 modified or rebuilt. Indeed, in many respects Martin-Baker designs were 'Meccano kits' and for the M.B.5 it is understood that the pilot's cockpit was just moved to a different pair of frames within the fuselage.
[Chapter 20] The experience gained in manufacturing the M.B.1 and M.B.2 was carried over to the M.B.3 but, whilst retaining the essential characteristics of the earlier designs with a fuselage primary structure built in steel tubing, the new aircraft introduced many new features. Metal stressed-skin panels with flush riveting replaced all of the fabric covering ...
[Chapter 19 on M.B.2] The wing had a triangular spar (a single spar built up of steel tubular members) and was fabric covered aft of the spar (as was the rear fuselage), but the forward fuselage and wing were covered by easily removable metal skin panels.
I have seen many contradictory opinions online, usually without sources. There seems to be general agreement the plane used a Griffon 83 with something like 2,340hp (though British Secret Projects says 2,305hp and Wiki 2,035hp).
On the construction, I am assuming the removable panels do not count as stressed skin (the attachment points are too few/loose to add structural strength?) but at least according to Buttler they do not cover the whole surface so the rear wings and fuselage could still be stressed skin.
I note Old Machine Press gives the Buttler book as its newest source, although it also gives the usual 460mph without stating the source, and adds "Some sources state the MB5 was prepared for a speed run in the fall of 1945. The Griffon engine was boosted to produce 2,480 hp (1,849 kW), and the aircraft reached 484 mph (779 km/h) on a measured course near Gloucester. However, the speed record claim seems highly doubtful."
