A newbies impression of the 109 and spit

[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.

[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.

[MiG-3U]

Originally Posted by 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.

In some degree I agree, the same revised loading table also has limits for the modified elevators:

1. With modified horn balance elevator (Spitfire modification No. 789): - 9.0 in. aft of datum point.
2. With Westland convex elevator (Spitfire modification No. 743) - 8.2 in. aft of datum point.
Note: - 1. & 2.apply to all propellers no elevator inertia device should be fitted.

So there indeed was design changes to solve the problem but I won't call that as a design problem because the loading needs grew over the original specification.

Over and out

[NZtyphoon]

Originally Posted by 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.

I think you're right about the narrow cg margin, not forgetting that when the Spitfire was designed in 1935-36 features like CS propellers, armour plate, armoured windscreen, IFF - even apparently small details such as extra ducting for gun heating equipment, shrouding for the gun bays etc - were three to four years into the future. Compare the equipment loaded into a pre-war Spitfire I with that loaded into a 1942 Mk V and the margin for error must have been relatively small.

Does anyone have any idea of how the Spitfire cg margins compare with (say) the P-51?