A newbies impression of the 109 and spit

[robtek]

All this writing, or better copy 'n pasting, doesn't change the fact that the stick forces and stick travel for the elevator control in the early marks of the spitfire were too low and that has been changed in the later marks with the "BoB-weights".

If the low forces in connection with the small travel weren't regarded as dangerous, no change would have been necessary!

[bongodriver]

If the low forces in connection with the small travel weren't regarded as dangerous, no change would have been necessary!

not true, it was merely improved, not changed because it was dangerous, was everything that changed with the 109 do so because it was dangerous? I keep hearing how fantastic the leading edge slats were and then they were removed.........

[robtek]

Originally Posted by bongodriver

not true, it was merely improved, not changed because it was dangerous, was everything that changed with the 109 do so because it was dangerous? I keep hearing how fantastic the leading edge slats were and then they were removed.........

Now that will be really, really hard to proof, All Bf109 / Me109 had and still have the slats!

And the rest of your opinion is grasping for straws, imo.

[bongodriver]

And the rest of your opinion is grasping for straws, imo.

IMO all the theories on the spitfire so far are the same.

[NZtyphoon]

Originally Posted by robtek

All this writing, or better copy 'n pasting, doesn't change the fact that the stick forces and stick travel for the elevator control in the early marks of the spitfire were too low and that has been changed in the later marks with the "BoB-weights".

If the low forces in connection with the small travel weren't regarded as dangerous, no change would have been necessary!

The reason bob-weights were adopted was because several Spitfire Vs had been destroyed through poor loading at squadron level; this has been explained by Supermarine's Chief Test pilot Jeffrey Quill, although some Spitfirephobes consider him to be so totally biased he's incapable of telling the truth Of course we have to believe these "experts' such as Crumpp or Barbi, and not Quill, who was the chief propagandist of the Spitfire:

In general configuration the Mk I and Mk II production aeroplanes were almost identical to the prototype and so there was no problem with their stability. (231-232)

The Mk III Spitfire did not go into production, but the success of the bobweight experiment in curing its instability...opened up the possibility of its use for later marks of Spitfire....which was just as well as we had to...respond to a nasty situation which developed in 1942.

The Mk V aircraft was...in full service with Fighter Command and,...a fair amount of additional operational equipment had gradually crept into the aircraft, most of it stowed within the fuselage. The aftmost acceptable position for the aircraft's centre of gravity had been fixed in the normal course of flight testing by the firm and by the A & AEE....Any rearward movement of the centre of gravity in service, for whatever reason, would begin to destabilise the aircraft. Therefore, for each sub-variant of the Mk V detailed instructions for the correct loading of the aircraft were issued to squadrons....However the importance of these loading instructions was not generally appreciated in squadrons and in the daily round of operational activity they tended to be disregarded....

There was thus a real chance that, as of that moment, in almost every squadron in the Command Spitfires were flying in a dangerous state of instability....Up to that time there had been a distressing and increasing incidence of total structural failure of Spitfires in the air, which was causing great concern in the MAP and especially at Supermarine. (pages234-235)

Once the bobweights had been introduced and, in later marks, the modified mass balances on the elevators...it was statistically established that, as soon as the longitudinal stability of the Spitfire was thus brought under control, the problem of the unexplained breakings-up of aircraft in mid-air,...'softly and suddenly vanished away'. (page 238 )

To say that they were adopted because of inherent design problems with the Spitfire Is and II is wrong; they were used on the Spitfire III because it had developed cg problems and adopted in Spitfire Vs because of poor loading and increased equipment.

[Al Schlageter]

Originally Posted by bongodriver

not true, it was merely improved, not changed because it was dangerous, was everything that changed with the 109 do so because it was dangerous? I keep hearing how fantastic the leading edge slats were and then they were removed.........

Some pilots had the slats were wired shut, but that was the exception not the rule.

[robtek]

Originally Posted by NZtyphoon

The reason bob-weights were adopted was because several Spitfire Vs had been destroyed through poor loading at squadron level; this has been explained by Supermarine's Chief Test pilot Jeffrey Quill, although some Spitfirephobes consider him to be so totally biased he's incapable of telling the truth Of course we have to believe these "experts' such as Crumpp or Barbi, and not Quill, who was the chief propagandist of the Spitfire:



To say that they were adopted because of inherent design problems with the Spitfire Is and II is wrong; they were used on the Spitfire III because it had developed cg problems and adopted in Spitfire Vs because of poor loading and increased equipment.

Sorry NZTyphoon, but to say that the bobweights were introduced because of the "poor loading ad squadron level" sounds absolutely unconvincing to me.

The bobweights were used to reduce the ease of motion when actuating the elevators, reducing this way the possibility to inadvertently overstress the airframe, regardless of the flightsituation (spin, overspeed or else).

[NZtyphoon]

Originally Posted by robtek

Sorry NZTyphoon, but to say that the bobweights were introduced because of the "poor loading ad squadron level" sounds absolutely unconvincing to me.

The bobweights were used to reduce the ease of motion when actuating the elevators, reducing this way the possibility to inadvertently overstress the airframe, regardless of the flightsituation (spin, overspeed or else).

It might sound unconvincing to you but its the truth - unless, like some others on this forum, you believe that you are more of an expert on the matter than Jeffrey Quill.

[MiG-3U]

Originally Posted by robtek

Sorry NZTyphoon, but to say that the bobweights were introduced because of the "poor loading ad squadron level" sounds absolutely unconvincing to me.

The bobweights were used to reduce the ease of motion when actuating the elevators, reducing this way the possibility to inadvertently overstress the airframe, regardless of the flightsituation (spin, overspeed or else).

http://target4today.co.uk/_posted_im...11/CoG_Iab.jpg

The inertia device (bob weighs in other words) was not needed if the CG was forward enough and the later marks, (VIII, IX...) did not have the device because the heavier engine moved the CG forward, 4-5 in. aft of datum point, except rare case of rear fuselage tank.

It can be said that the original CG limits were too aft with Rotol propeller and longitudal stability suffered, hence warnings in the early version of the Spitfire II manual. However, warnings were removed once the limits were revised.

Over and out

[JtD]

It is always possible to exceed safe margins through improper loading, but in case of the Spitfire, this margin was small by design; and if it is impossible to maintain safe limits in everyday service, it is a design problem. Saying it was just improper loading, or saying it was just faulty design for that matter, imho only is half the truth.