# Spitfire Mk.21's redesinged wing



## gomwolf (Oct 18, 2014)

Hello~. 

There is a problem about Spitfire Mk.21's redesigned wing. I try to find information about this wing and found some articles confront each other. It make me confuse, please help me guys!

Some articles told this redesign wing have laminar flow airfoil. But there is no information about this wing's airfoil, even name of airfoil's form.
others told redesign wing have same airfoil with before spitfire(NACA 2213(root), NACA 2209.4(tip). Changed thing is aileron for high speed.

In the book 'Spitfire's forgotten designer' written by Mike Roussel, Spitfire Mk.21's wing have laminar flow airfoil.
I think, if Spitfire Mk.21 have laminar flow airfoil, it have to big change in performance, especially in top speed. but Spitfire Mk.21's top speed(around 446mph at +18lb) is not big different with Spitfire Mk.XIV(around 447mph at +18lb). It is weird
In UIUC Applied Aerodynamics Group's airfoil data(The Incomplete Guide to Airfoil Usage), Spitfire Mk.21's airfoil is NACA2213(root), NACA2209.4(tip)


Which one is right? There is no certain evidence, which give me answer?(Blue prints or documents?) Please guys, help me!


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## tomo pauk (Oct 18, 2014)

The Mk.21 retained the NACA 2200 series profile, but the wing was redesigned and improved vs.older Spitfire wings. The laminar flow wing was introduced with Spiteful.


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## gomwolf (Oct 18, 2014)

Could you give me some documents that can prove your word? Like blueprint or documents? If you have, please open it to me.

I saw lots of insist about that each side, but there is no evidences can prove there insist...


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## gomwolf (Oct 18, 2014)

Could you give me some documents that can prove your word? Like blueprint or documents? If you have, please open it to me.

I saw lots of insist about that each side, but there is no evidences can prove there insist...


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## stona (Oct 18, 2014)

The Type Record for the prototype 356/1 Spitfire F Mk 21, of 1st May 1943, states 'wing aerofoil section NACA 22 series of elliptical planform of Spitfire Mk I extended 1.67 ft on each side'

No laminar flow wing but it was extensively modified. The confusion probably arises from the MAP. The Mk 21 was provisionally referred to as 'Victor' and a letter from the MAP to Supermarine quoted in Spitfire the History (StH) says that "The F 21 Victor aircraft on order are to redesignated F21 Laminar flow wing."

There are nice drawings on page 468 of my version of StH.

Cheers

Steve


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## gomwolf (Oct 18, 2014)

thank you stona! I will find that book!


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## spicmart (Dec 30, 2021)

*"Redesigned late wing*
As the Spitfire gained more power and was able to fly at greater speeds the risk of aileron reversal was increasing so the Supermarine design team set about redesigning the wings to counter this possibility. The original wing design had a _theoretical_ aileron-reversal speed of 580 mph (930 km/h), which was somewhat lower than that of some contemporary fighters.[8]​ The new wing of the Spitfire F Mk 21 and its successors was designed to help alleviate this problem; the wing's stiffness was increased by 47 per cent and a new design of aileron using piano hinges and geared trim tabs meant the theoretical aileron-reversal speed was increased to 825 mph (1,328 km/h).[8]​[9]​[10]​ This wing entered service on the Spitfire XXI. The standard armament was now four 20mm Hispano IIs or the shorter, lighter Hispano V cannons, each with 150 rounds per gun."

This is from Wikipedia (I know). So would that mean that this Spitfire wing would surpass all other WW2 fighter wing designs in stiffness?
Taken these numbers it must have given the Spit a tremendous advantage at roll rate and in a dive recovery. 
Has anybody the stiffness/aileron reverse rates of other fighters?


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