Why did the Me 109 roll and turn so bad at speed?

[bf109xxl]

From "The German Fighter since 1915" by Rüdiger Kosin, Putnam, 1988:

The Author...was design office group director and engineer pilot in the experimental flight section of the Ernst Heinkel aircraft company at Rostock-Marienehe. At the turn of the year 1936/37 same activity at the Arado aircraft works in Brandenburg on the Havel. From 1941 to the end of the war was director of the aerodynamic design division. From October 1945 to May 1946 wrote a report for the Royal Air Force. From May to October 1946 resided in the British Interrogation Centre in Wimbledon. November 1946 to July 1950 worked in France — Decize (Nievre) — in the Oestrich group on jet engine development. July 1950 accepted an offer from Fokker in Amsterdam. Design of a supersonic fighter. When the firm withdrew from the project, accepted an offer from the U.S. Air Force to work in America on the continuation of a development process in Germany interrupted by the war. From January 1952 to July 1955 worked in Wright Air Development Center in Dayton, Ohio. In July 1955 accepted an offer from the Northrop Corporation, Los Angeles, California. Worked as Research Scientist, director of the design office, project director and finally, until December 1968, as Technical Assistant, Vice President Engineering.
...

pp.142-144

From this comparison it is clear that the Fw 190 should have been the inferior aircraft, but it had two clear advantages: superior roll manoeuvrability and acceleration in a dive, which gave the pilot the chance to get into a firing position from an unfavourable situation, or to escape from the enemy if he was surprised. The Fw 190 gained a reputation for quite outstanding roll response. In contrast to the Bf 109, whose excessive aileron control forces at high speed were a constant source of complaint, the Fw 190's aileron force compensation was excellent. Both aircraft were fitted with ailerons whose leading edge was forward of the pivot axis. On the Bf 109 this part had a circular arc-shaped profile which was designed to keep the gap between aileron and wing as narrow as possible. The Fw 190 featured Frise ailerons, in which the aileron leading edge is extended to form a sharp edge. On the up-going aileron this part projects below the wing, and air pressure reduces the load produced by the top surface of the aileron. The Fw 190's wing also possessed great torsional rigidity. When an aileron is deflected, the wing tends to twist in the opposite direction. This tendency increases as speed rises, until the aileron reversal speed is reached, i.e. force is required to move the aileron, but its deflection has no effect. With stressed-skin construction the wing skin has to be strong enough to absorb the bending forces, and if this is the case the skin has an abundance of strength for the torsional loads, i.e. torsional stiffness is high. In contrast, the traditional Messerschmitt single-spar wing, as used on the 109, had plenty of strength in the bending plan, but relatively low strength in torsion. Torsional stiffness was further reduced by the large cut-outs and apertures in the wing skin for radiator, undercarriage and weapons installation.
The wingtip adopted for the 109F (and also for the Bf 110), was different from the previous version, but the change was not intentional. As an experiment a 109E wing was built with the span reduced by one metre. This machine, the Bf 109 V24, was tested and the wing found to be too small. Rounded wingtips were added to bring the wingspan up to around 10 m again, but the ailerons were not extended, and now ended at 87 per cent of the semi-span. The overall result was a further decline in aileron effectiveness. The illustrations show the fundamental differences in the wings of the two aircraft. The top and bottom shells of the Fw 190 wing were constructed separately, and connected by two widely spaced webs. The forces acting on the wing skins were transferred to a massive spar at the wing root, located at about one third of the chord. The spar was continuous from one side to the other, and formed the main attachment between wing and fuselage. The aft web extended as far as the fuselage side, where it was connected to a reinforced bulkhead. Full ribs were employed at the highly loaded points, where the undercarriage and weapon mountings were attached, with half-ribs used for the remainder.
The essential load-bearing element of the Bf 109 wing was a stout spar, at 45 per cent of the wing chord. It was located so far aft in order to accommodate the wheels. The upper wing skin was uninterrupted, and was stiffened with widely spaced ribs and longitudinal profile strips. A large proportion of the undersurface was covered with removable hatches, located between strong full ribs. The problem of transferring the forces around the various apertures called for some imaginative engineering, and was a daring piece of work. A powerful spar bridge was an integral part of the fuselage, and the two wing panels were attached to the fuselage sides at three points: the top and bottom spar flanges were connected to the spar bridge, while the third attachment point was part of the undercarriage spring strut fitting. The same fitting also held one end of the engine support strut; thus three substantial loads were transferred into the fuselage via a single component, albeit fairly complex and rather difficult to make.

 

[WARSPITER]

Or the fact that the world was locked.in a great depression and an abundanve of food was not available like today.

Look at the photos of Germans, Americans and Englishmen - they were all lean.

Diet is a definite difference.

Average male height for German males by year of birth : 1900 - 169cm (just over 5' 6 1/2 "), 1940 - 175cm (whisker under 5' 9"), 1980 - 181cm (5' 11 1/4").

An average height Luftwaffe pilot born in 1920 would stand at 173.3 or just over 5' 8".

 

[Snautzer01]

Diet is a definite difference.

Average male height for German males by year of birth : 1900 - 169cm (just over 5' 6 1/2 "), 1940 - 175cm (whisker under 5' 9"), 1980 - 181cm (5' 11 1/4").

An average height Luftwaffe pilot born in 1920 would stand at 173.3 or just over 5' 8".

Even shorter according What was the average height of a German soldier in WW2?

 

[GreenKnight121]

From reading memoirs, reports, etc written in the WW2 or immediate post-WW2 period, the average weight of the US soldier/sailor at entry into service was 150#-165#, and average height was 5'6"-5'8" (depending on place of origin - 140# at 5'6" was not uncommon) - a 6' 180# man was considered "large".

 

[bf109xxl]

 

[special ed]

I mentioned in another thread somewhere in the forum, of a visit to a museum in Colorado Springs in 1960 and was amazed at the small stature of the U.S. pioneers going west. The exhibits were donations from locals which came from their ancestors. The civil war uniforms looked childlike, to fit men about 5ft to 5ft 5in. I was amazed that men this size carried rifles & bayonets as long as they were tall weighing as much or more than my M-1 Garand. The wedding gowns looked as if they were for children or large dolls. Women appeared to have been 4ft 8in to 4ft 10 or 11in. Remember most of the people who wore these clothes were immigrants or their immediate offspring. My opinion has been the agriculture of the north American continent made the difference. My father, born 1912, was about 5ft 8-9in, while June of 1959, when entering USAF, I was 5ft 11in and about 135-140 pounds, and was considered skinny. My father was also more physically fit than I, and finally realized that he was losing some strength when he phoned me to help him reinstall the exhaust manifold on his boat's inboard engine. I came, expecting some problem, reached into the boat's engine well, raised the manifold and put it on the studs, commenting, "What was the problem?"
"It's just too damn heavy."

 

[ThomasP]

I had an occupational physical when I was 21 where they did a BMI (Body Mass Index) check. At the time I was 5' 6" and weighed 176 lbs. I was so lean that you could see pretty much every muscle on my body though not the veins everywhere like on bodybuilders that have reduced their water mass before contests. Per the BMI I was 'overweight'. When I was 27 I had another occupational physical where they checked my BMI. In the 6 years between the BMI checks I had grown to 5' 6.25" and weighed 195 lbs. You could still see nearly all my muscles. Per the BMI I was 'Obese'.

Everyone in the family said I was built like dad, but with a heavier build. My dad was 28 in 1941, and was like me in that he had very little fat on him. When he had his military physical he was 5' 6" tall and weighed 145 lbs.

edit Oops! I typed 'gained 195 lbs' but meant 'weighed 195 lbs'. Changed it.

 

[PAT303]

I had an occupational physical when I was 21 where they did a BMI (Body Mass Index) check. At the time I was 5' 6" and weighed 176 lbs.

At 21 I was 6'1'' and weighed 96kg-212lbs, I am eye level with the top frame of a Spit 21 windscreen, if I was in the BoB I'd be a Homer Simpson.

 

[GregP]

Well, the retractable tail wheel (with open aperture, no door) was actually deleted after the F model. However, some early G versions seem to have had the retractable function retro fitted, probably with F parts. Likewise, the reference to larger tail area is possibly more of a E to F version change, so It looks like a crib of an F report.
Edit, pics show TP814 was actually a tall-tail 109 G, so that was the extra area.
Eng

The Bf 109 G series started off with a retractable tail wheel. When they went to the B-4, the tail wheel tire got bigger and could not be retracted into the same space, so they stopped retracting it.

Edit corrected to G-2: The Bf 1009 G-2 DID have a retractable tail wheel, AFAIK.

 

[Holtzauge]

This chart from NACA report 868 has probably been posted a few times before on this forum but it could be good to have in this thread as well since it shows some of the Bf-109's main competitors.

In the figure for the Bf-109F2 I posted earlier the apex for the roll rate was 80 deg/s at 440 km/h IAS so that is about 273 mph IAS. Looking at the figure below we can see that that is below what the P-47, P-51, P-40 and Spitfire managed. In addition, it's quite clear that the American fighters do much better at higher speeds.

 

[Engineman]

The Bf 109 series started off with a retractable tail wheel. When they went to the B-4, the tail wheel tire got bigger and could not be retracted into the same space, so they stopped retracting it.

The Bf 1009 B-2 DID have a retractable tail wheel, AFAIK.

Hi!
Am I reading this right? B-2, B-4?

Cheers

Eng

 

[Holtzauge]

The La-5 had roll comparable to the FW 190 and somewhat better than Bf 109G. But I asked about the LaGG-3...
There is a hypothesis (not mine) that the Bf 109 versions F and onward had insufficient wing stiffness and suboptimal aileron design. I cannot evaluate the validity of this hypothesis by myself.

Hans-Werner Lerche who tested both the La-5FN and the Yak-3 in Rechlin.

This is what the English translation of Lerche's Rechlin evaluation report (No. 22470/45) of the La-5 says:

Under section: Stability, control power and effectiveness: "Aileron effectiveness is outstanding. At Va 450 km/h (280 mph) a roll takes barely 4 sec; at Va 600 km/h (373 mph) aileron forces become high but can be assisted by rapid rudder movements."

Under section: Tactical conclusions and advice :"Aileron effectiveness is better than that of the Bf-109."

So 360/4 is only 90 deg/s and even if we allow for roll acceleration and that the roll time may have been a couple of tenth seconds shorter, this is still a far cry from the Fw-190's 142 deg/s at 280 mph (NACA report 868). This is also most likely why the report compares to the Bf-109 (80 deg/s at 280 mph) and not the Fw-190, because the La-5 does not even come close to the Fw-190's 140 to 145 deg/s.

 

[spicmart]

This chart from NACA report 868 has probably been posted a few times before on this forum but it could be good to have in this thread as well since it shows some of the Bf-109's main competitors.

In the figure for the Bf-109F2 I posted earlier the apex for the roll rate was 80 deg/s at 440 km/h IAS so that is about 273 mph IAS. Looking at the figure below we can see that that is below what the P-47, P-51, P-40 and Spitfire managed. In addition, it's quite clear that the American fighters do much better at higher speeds.

View attachment 78300300

It's astounding that the Spitfire with its large, "weakly built" wing and relatively small ailerons rolled relatively quick, especially the clipped wing variant. Quicker than the small winged 109.
Most sturdier-built, and by that heavier, planes roll quicker at high speed where their structure takes the higher load forces better.

 

[pbehn]

It's astounding that the Spitfire with its large, "weakly built" wing and relatively small ailerons rolled relatively quick, especially the clipped wing variant. Quicker than the small winged 109.
Most sturdier-built, and by that heavier, planes roll quicker at high speed where their structure takes the higher load forces better.

I think you are misunderstanding the issue. It takes little effort with a 2-3 foot long lever called a "key" to roll a perfectly round 10 ton pipe along a perfectly flat bench, I did it all the time at work. A WW2 warplane suspended by wires as in a museum but with the wings unattached will spin on its longitudinal axis with very little effort at all. At high speed the potential ability of ailerons to generate a rotational force is huge, but there are problems that aero engineers can explain and I cant. To exert a force the aileron needs to be fixed to a wing that doesnt move at all, but the wing does deflect, eventually it deflects so much that the resultant force is the opposite to what you want, this is called aileron reversal. before that point there is less and less resultant force giving the pilot the sensation that the controls are locked. You cannot see or estimate such aerodynamic properties with your eyes, there was nothing inn the Spitfire that was "weakly built" in that respect, a few may have been better but that doesnt mean weakness, those wig tips slowed rate of roll but added to rate of climb and climbing to intercept was the Spitfires "day job".

 

[GregP]

Hi!
Am I reading this right? B-2, B-4?

Cheers

Eng

Bf 109G-2. My mistake, not yours.

 

[Shortround6]

The Spitfire had at least 3 different roll rates. Spitfire experts maybe able to come with more.
You have the original wing and fabric ailerons (and original control set up?)
You have the metal covered ailerons. The fabric ones ballooned and made a mockery of the expected deflection angles.
You have the clipped wings.
What I don't know is any changes to pullies or leverage or changes to shape of the ailerons nose or ???

Leaving the whole Spitfire 21 wing out of it.

 

[pbehn]

The Spitfire had at least 3 different roll rates. Spitfire experts maybe able to come with more.
You have the original wing and fabric ailerons (and original control set up?)
You have the metal covered ailerons. The fabric ones ballooned and made a mockery of the expected deflection angles.
You have the clipped wings.
What I don't know is any changes to pullies or leverage or changes to shape of the ailerons nose or ???

Leaving the whole Spitfire 21 wing out of it.

You mean "it's complicated"? I was looking for a one word answer.

 

[Shortround6]

You mean "it's complicated"? I was looking for a one word answer.

You have been here for more than a week, you know you won't get one word answers from me

 

[Engineman]

The Bf 109 G series started off with a retractable tail wheel. When they went to the B-4, the tail wheel tire got bigger and could not be retracted into the same space, so they stopped retracting it.

Edit corrected to G-2: The Bf 1009 G-2 DID have a retractable tail wheel, AFAIK.

Well, this is the situation.
Messerschmitt had planned both outer mainwheel doors and the retractable tailwheel on the Bf 109 F designs. However, only the retractable tailwheel made mass production on the F. Notwithstanding that, there is photo proof of outer mainwheel doors on some G versions but these were unusual, rare and probably one-offs.
The retractable tailwheel was seen on occasional early Bf 109 G aircraft, but the same applies.
Neither the outer M/W doors or the retractable tailwheel were standard fit on the production G aircraft. They are rarely seen and were non-standard.

Cheers

Eng

 

[Holtzauge]

It's astounding that the Spitfire with its large, "weakly built" wing and relatively small ailerons rolled relatively quick, especially the clipped wing variant. Quicker than the small winged 109.
Most sturdier-built, and by that heavier, planes roll quicker at high speed where their structure takes the higher load forces better.

The Spitfire had at least 3 different roll rates. Spitfire experts maybe able to come with more.
You have the original wing and fabric ailerons (and original control set up?)
You have the metal covered ailerons. The fabric ones ballooned and made a mockery of the expected deflection angles.
You have the clipped wings.
What I don't know is any changes to pullies or leverage or changes to shape of the ailerons nose or ???

Leaving the whole Spitfire 21 wing out of it.

The Spitfire roll data I posted earlier (NACA 868) is for the Mk V with metal Frise type ailerons. The Mk 21 had stiffer wing and servo tab ailerons and did about 120 deg/s at 200 mph IAS (data from Smith's Spitfire lecture at the RAeS after the war). It was not just the Mk 21 that was modified, because there were other changes between the Mk I and the Mk V other than the just changing from fabric to metal covering since the aileron reversal speed went up in the Mk V. If they did something with the control circuit I don't know but they did stiffen up the wing a bit since the Mk I had an aileron reversal speed that was just 480 mph IAS.

The roll data compared so far is for the roll rate around the apex for each aircraft so close to the crossover point where the pilot can no longer apply full deflection but starts to be limited by the stick forces. But at this speed, even the Spitfire's and Bf-109's relatively weak wings are still stiff enough and don't twist that much. The aileron reversal speed (at which the aileron begins to work as a servo tab twisting the wing so that the net effect is zero roll rate) for the Spitfire Mk V was around 580 mph IAS (ref RAE 1231) so quite a bit higher.