A newbies impression of the 109 and spit

[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

[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.

The text you quoted, nztyphoon, says that the Spit1a b and the spit 2 had no stability problems and then continues with the cog problems of the spit 5.

There is nothing wrong with this text, but is it really applicable to this topic?

If the spit2 didn't had have stability problems, as you quoted, why were bobweights mounted?

[Crumpp]

Bob-weights have absolutely nothing to do with CG limits. The stabilty margin will shift with CG limits and the early mark Spitfire did have stable load conditions.

However all of that is completely irrelevant. CG shirts from consumption of consumables like oil and avgas. The NACA was well aware of all these characteristics and could do weight and balance.

The solution for the unacceptable and dangerous longitudinal instability of the Spitfire was bob-weights. These were added not because the NACA made a mistake in some half baked theory on weight and balance calculations. They were added by the RAE to correct a serious stability and control issue with the design.

[Crumpp]

Originally Posted by NZtyphoon

http://www.spitfireperformance.com/k...cg-diagram.jpg

Yeah right, it says "C.G Diagram" in nice big letters at the bottom so people who can read understand it has nothing to do with the centre of gravity of Spitfire Mk Is.

NACA report Measurements of the Flying Characteristics of the Spitfire Va: As per usual Crumpp has fudged what the report actually says:



Crumpp has chosen to completely ignore that NACA's own report states that their calculations might have been in error, nor did NACA know what the cg was with full military load. " The NACA was well aware of the CG limits and capable of performing a proper weight and balance." completely wrong.

You want to quote the rest of this paragraph after "CG with full Military Load is not known"? You want it explained as to what they did?

The same longitudinal instability characteristics noted by the NACA are found as warnings in the Operating Notes written by the Air Ministry. The accident statistics confirm the validity of the warnings and the NACA findings.