Bf109G-6 Question!

Koopernic said:

The NACA 868 report gives no information on Me 109 roll rate at all. There is no comparison. It is, thanks to Cranfield University, mirrored here:
http://naca.central.cranfield.ac.uk/reports/1947/naca-report-868.pdf See page 166 figure 47.


For the German DVL report we have:

200 kph = 45 deg/sec (0.8rad)
300 kph = 68 deg/sec (1.2rad)
400 kph = 83 deg/sec (1.45rad)
480 kph = 20kg/44lbs limit
500 kph = 88 deg/sec (1.55rad)
600 kph = 91 deg/sec (1.6rad) - peak value
700 kph = 56 deg/sec (0.98rad)
800 kph = 23 deg/sec (0.4rad)


Te stories about the roll rate of the aircraft being set in cement somewhat hyperbolic. The above data is in TAS and as the document show the tests are made in H=3km (H = Höhe = altitude) about 10000ft.

In in 3km alt :

600km/h TAS = around 510km/h IAS = 91°
700km/h TAS = around 595km/h IAS = 56°
800km/h TAS = around 680km/h IAS = 23°


Me 109F2 at 595kmh (370mph) IAS, 3000m (10000ft) the Me 109F2 is rolling at 56 degrees sec (30kg or 66lbs stick force)
Sptifire V at 595kmh (370mph) IAS, 3000m (10000ft) the Spitifre V is rolling at 56 degrees sec (50lbs stick force)

Click to expand...

Note that the NACA 868 does not specify whether the Spitfire (unspecified mark) had metal or fabric covered ailerons; it could also be noted that the roll rates of the clipped wing Spitfire were considerably higher than that of the 109: 81º/sec @ 370 mph (50 lbs stick force), such that at higher speeds the Spitfire achieves near parity with the Fw 190. Thus a relatively simple modification increased the efficiency of the Spitfire's ailerons, while presumably reducing the wing's aeroelasticity.

While the NACA extract on the Morris/Morgan report is often quoted by those who like to claim that the Spitfire suffered from a poor wing design. However, it is only a second hand extract from a complete report which, AFAIK has not yet been available on the internet - it would be interesting to know what the full report says about the Spitfire's wing.

Aozora said:

Note that the NACA 868 does not specify whether the Spitfire (unspecified mark) had metal or fabric covered ailerons; it could also be noted that the roll rates of the clipped wing Spitfire were considerably higher than that of the 109: 81º/sec @ 370 mph (50 lbs stick force), such that at higher speeds the Spitfire achieves near parity with the Fw 190. Thus a relatively simple modification increased the efficiency of the Spitfire's ailerons, while presumably reducing the wing's aeroelasticity.

While the NACA extract on the Morris/Morgan report is often quoted by those who like to claim that the Spitfire suffered from a poor wing design. However, it is only a second hand extract from a complete report which, AFAIK has not yet been available on the internet - it would be interesting to know what the full report says about the Spitfire's wing.

Click to expand...

All of the aircraft in the NACA report are types that were in service in 1943, at earliest 1ate 1942. The clipped wing spitfire was based on the Spitfire V which already had metal ailerons. Douglass Bader was one of the first to use metal ailerons and he was shot down and captured in 1941.
I suppose it's possible that the NACA made one exception and chose to display the roll rate of an out of date Sptifire variant but I doubt it. The NACA lateral stabillity report was not about making American, German or British aircraft look good or bad via application of selective bias. It was about engineers getting to the bottom of performance and handling differences to give the men a better machine to survive and fight in. I would expect that objectivity precedes national pride in that area.


We have other Spitifre roll rate reports, an RAE report with a metal aileron Sptifire VA at 30lbs stick force (60 degrees/ minute thus consistant with the 50lbs 90+ degree NACA report) and another of the Spitifre XII Griffon with and without clipped wings. They are consistent with this being a metal aileron spitfire. Certainly clipping the wings eliminated the tips which presumably were twisting in the wrong direction and undermining roll rate but also cost climb rate and maneuverability (slightly). The losses seem to have been unacceptable except in the case of the Spitfire XIV Griffon which had plenty of climb from its engine anyway and which mostly operated with clipped wings. Either way the Fw 190 rolls at least twice as fast as a full wing spitfire at any speed and about 33%-25% faster than the clipped wing version with the gap getting smaller at high speed. Having said that, the Clipped wing Spitifre is a fast rolling aircraft but even it as the Fw 190 was out-shadowed by the P-51 with its superior wing structure and its NACA internal aileron balancing technology. Furthermore shortly after this report the American Navy fighters, the Hellcat and Corsair received geared spring tabs that more than doubled their high speed roll rate


We also have the the books, notes, speeches and articles of people such as Jeffery Quill, the test pilot and Joseph Brown, the engineer responsible for the Spitfire after Mitchell retirement due to cancer. He took the Spitfire from the Mk I to the Mk 24 and all note the aeroelastic issue that impose a limmitation.

Supermarine/Vickers tried several improvements:
1 metal ailerons
2 friese ailerons
3 smaller ailerons (better at high speed) eg Mk VIII
4 clipped wings (MK V, XII and XIV)
5 strengthened standard wing Mk XVIII
6 completely new wing on the Mk 21 onwards

I should note that lengtening the nost of an aircraft seems to adversly effect its roll due to inertial coupling.

With all of these modifications, especially the use of clipped wings they were probably more successful than Messerschmitt improvements on the older Me 109 design.

Unfortunately we know little factual about the use of spring tabs on the Me 109 to improve roll rate. We also know that Messerchmitt developed the Me 209-II which was 63% common with the Me 109 (it had a new wing, new engine/nose and modified tail which eventually made it into Me 109K production).

The point is everyone was addressing the roll rate issue, Focke-Wulf apparently with hydraulics as per the P-38J. The various aircraft had their own unique problems.

I'd like to add, to anyone reading this post, that I am not one to say the Spitfire wing was inferior or the Me 109 was better, to be honest I think the Spitfire was better. I think the Me 109 should have been rotated out of production by 1943 and if not more radically modified. However I also think the 109 was somewhat over maligned and I tend to defend it from that point of view. The speed range the Spitifre needed to have a good roll rate it certainly had an adequate one.

Reginald Mitchell had a 'saying' which has helped me in my engineering career. He said "one should use advanced technology to simplify things", that has certainly helped to keep things in perspective for me.

Hello Koopernic
IMHO most of us here know that 109 was a better plane than the popular image of it. It was a top class fighter most of the war, unfortunately to the Germans it was somewhat let down by the DB 605A with its problems for a very critical timeframe from autumn 42 to the autumn 43. IMHO 109E was the best fighter around from the beginning of the war to the summer 40 when the Spit with CSU and 100oct fuel became appr. equal. Again 109F was IMHO the best short-range fighter around albeit somewhat lightly armed when fighting against heavy bombers or Il-2s. IMHO the low-point of 109 was 109G-6 with its necessary modifications which made its more effective armed and stiffer but also heavier without compensating extra power when at the same time Spit IX and P-47 got better and more powerful powerplants (the former Merlin 63/66 and the latter water injection and broader airscrew blades). Only the appearence of 109 G-6A/S and 109 G-10 gave substantial improvement at high level and 109 G-14 at low and medium altitudes.

And one must remember that Soviet fighter pilots generally thought that the "Messer" was more dangerous enemy than the "Fokker". I don't know but I suppose that for the Il-2 crews it was other way around.