Leading edge shape on German fighter aircraft?

[drgondog]

The Optimal Low (est) Induced Drag wing plan form is elliptical. That pure elliptical planform must also have a zero washout to achieve Minimum Induced Drag via an elliptical lift distribution. Interesting, but impractical for real world application - particularly low speed/near stall flight envelope where either slats or twist is required for roll authority near stall..

Wing tip to Root chord ratios along with trapezoidal planforms are a solution to a.) approaching an elliptical lift distribution, while b.) yielding better manufactuarbilty. Wing tip shapes are also features considered to reduce/diffuse induced drag.

Wing areas are principally adjusted due to either a.) high priority for low speed maneuver (such as carrier deck), b.) storage (i.e fuel) and c.) reduce weight to wing area (W/L) for a variety of other reasons than landing (climb performance, lower AoA for comparable speed and weight compared to smaller wing area will slightly reduce profile drag). On the other hand more area means more weight, more friction drag.

A Corsair is heavier than a Mustang but has 15% more area and 10% less W/L. It also has 50% more parasite drag and a significantly higher compressibility factor at high speed. In the optimal power envelope for the Corsair, it will outclimb and out turn the Mustang - below 20,000 feet. Above a certain altitude the merits of the Rolls deliver more Thrust HP proportionately to the Mustang and the manueverability performance advantages reverse.

However because the significant differences in parasite drag due to both the laminar/low drag shape, the lower friction drag, and the lower compressibility drag rise of the NACA/NAA 45-100 wing vs the NACA 23018 (root), NACA 23015 (wing fold chord) of the F4U - The Mustang will always be faster at comparable Power settings.

 

[Elmas]

The prototipe and the first batch of Macchi MC 200 had a very sharp leading edge

and that caused bad stall and instability problems, expecially handling the planes in the "italian way"...

In the following series the profile was changed (not too difficult to do, the Italian fighters were practically hand-built, and so no complex realigning of complex machinery was neeed...) and proper wash-out introduced. After these changes the wing was so successfull that it was retained in both MC 202 and 205

 

[Elmas]

Some rumors say that was an Italian test pilot, Adriano Mantelli, ace of the Civil Spanish War, that, worried by the instability of the new monoplane, by his own initiative, grabbed some balsa boards, glued them to the leading edge, shaped them with a rasp and covered the whole with doped fabric, all in just one night.

Very early the following morning he took off to test the plane, with great success..

Of course the designers and some test engineers of the Reparto Sperimentale di Volo denied completely this story...

 

[Wurger]

 

[swampyankee]

The leading edge of the wings of German fighter aircraft seem to be rounder/blunter than those of many other nation's planes (of course with exceptions). What advantages and disadvantages does it have?
Also their nose, i. e. the spinners seem not as pointed. does anybody know more?

Sorry to resurrect this necrotic thread...


Do recall that the Bf109 used NACA airfoils, possibly as NACA had spent quite a lot of time, money, and effort in systematic investigations into airfoil properties and NACA's catalogue was deep, well-documented, and full of high-performance airfoils which were quite well-characterized.

Germany had some quite good aerodynamicists (so did the US, UK, France, Italy, etc), so they would have recognized that, so long as there's no separation, shape of things like spinners is really not terribly important for drag. The comparatively "pointy" spinners of US and UK aircraft may have been more because of manufacturing concerns than aerodynamics.

 

[dedalos]

I believe , it is clear that at the mid and late part of the war the wing shape of both the 109 and 190 was so inferior in comparison to the allied fighters that put the jagdwaffe in severe disadvantage. The Bf109K had a clean fuselage ,and covered landing gear. The Fw190D had a smaller frontal area by 9%. Both these planes received engines with similar performance at low level with the allied ones. Both planes had significantly smaller wings than the western fighters. Despite all these facts , both planes were slower or,at best, equal in low level speed to their enemies . A clear indication of the inferiority of their wings
I have read that the Fw190D would require 2400 hp to reach 644km/h on 0m altitude. The Fw190A9 on 2400hp, according to crumpp, was able just for 590km/h. The Sea Fury on 2400hp was able for 660 km/h ! The P51 650km/h with just 2000hp t ( The 109K at 1.98 ata was 40km/h slower than the P51 on the same horsepower despite the fact that it was a very much smaller aircraft!!)
Another indication of the inferiority of the german wing profiles was the comparison with the italian 5 series fighters. The Fiat G55 with DB605A cleared for 1,3 ata ,3 20mm guns and 21 square meters wings was , just 10-15km/h slower than the Bf 109G6 cleared for 1,42 ata with just one cannon and 16,5 square meters wing! The prototype G56 could just touch 690-700 km/h without MW50 and 3 cannons, the Fw190D9 required MW50 to reach such speeds despite the fact that it had 3 square meters smaller wing and only 2 cannons!

 

[tomo pauk]

I believe , it is clear that at the mid and late part of the war the wing shape of both the 109 and 190 was so inferior in comparison to the allied fighters that put the jagdwaffe in severe disadvantage.
...
Another indication of the inferiority of the german wing profiles was the comparison with the italian 5 series fighters. The Fiat G55 with DB605A cleared for 1,3 ata ,3 20mm guns and 21 square meters wings was , just 10-15km/h slower than the Bf 109G6 cleared for 1,42 ata with just one cannon and 16,5 square meters wing!

Those were American wing profiles - both 2R and 230xx series originated from NACA Jokes aside, the 2R profile really looks blunt at the leading edge, even with 14.2% thickess at root on the Bf 109. People in Germany were aware of shortcomings of some wing profiles in service A/C, hence eg. Me/Bf 309, plus swept wing. BTW - I'm afraid that we don't know how good exactly were the cooling systems on Bf vs. Fw. vs. Fiat.
Thing with 109G6 was that it lost most of the streamlining the G2 had - bulges for the HMGs + fixed tailwheel will slow it down. The 109G2 was faster than Fiat G.55 by ~30 km/h.

The prototype G56 could just touch 690-700 km/h without MW50 and 3 cannons, the Fw190D9 required MW50 to reach such speeds despite the fact that it had 3 square meters smaller wing and only 2 cannons!

IIRC the G.56 was good for 685 km/h, same as the Fw-190D9 as-is. HMG installation on the D9 was draggier affair than a MK 108 acting as a prop cannon. G.55/56, being a big aircraft, managed to have the HMGs well tucked in.

All of my favorite scenarios for what-if Fw 190 and Bf 109 include deletion of cowl MGs as the 1st step

 

[drgondog]

As Tomo pointed out the 2R for the 109 and NACA 23015 (IIRC) for the FW 190 were NACA derivative airfoils. You have to look further than the wing to dig out the Drag issues for the 109. Hoerner points to many contributors other than profile drag of the wing. Not the least were with wheel well/main gear, the friction drag due to the surface imperfections, and camo paint, parasite drag of canopy and radiator cooling intakes.

Same basic wings as F6F, F4U, P-38. Many pilots will tell you that they had a tough time catching an FW 190 on the deck with a 51, with no hope in a P-38 or P-47 down low. Ditto Spit. HP and supercharger scheme dictated comparative performance in most cases, save the 51 could take significant advantage due to low drag while having less Hp..

 

[Shortround6]

One can look at the change between the 109E and the 109F to see that there are plenty of other things going besides just the wing airfoil profile and wing area. Trying to pick out one thing on two or three different aircraft and place ALL the blame (or credit) on that one difference is probably going to lead to wrong conclusion.

 

[dedalos]

One can look at the change between the 109E and the 109F to see that there are plenty of other things going besides just the wing airfoil profile and wing area. Trying to pick out one thing on two or three different aircraft and place ALL the blame (or credit) on that one difference is probably going to lead to wrong conclusion.

If you read my post carefully, you see that i used the K version . A version that had corrected most aerodynamic issues of the fuselage and also introduced main landing wheels covers. There were left only minor improvements to be done( new windshield, perhaps under belly radiator,). Even if we add 12km/h due improved surface quality (impossible at that stage of the war but certainly it was not the aircraft s fault), another 12km/h from uncertain improved propeller and perhaps minor engine cowling improvements , still the 109K ,on the same horsepower, remained slower than bigger aircraft.Clear indication of wing profile inferiority
The same goes for the 190D. Even with engine gap sealed, landing gear doors, no ETC rack and decent wing surface quality was not competitive.On 2100ps was 40km/h slower than the P51 on 2000hp, 4-12km/h than the La7 on 1850hp, and 30km/h slower than the Tempest V which had 10 square meters more wing surface . True , an integrated engine cowling , the replacement of the Mg131s by engine cannon,improved radiator type and reduced armor would add 10-20 km/h but still is clear that something was wrong with the wing profile

 

[drgondog]

Dedalos - excellent summary.

Parting comment - notably performance comparisons occur for M>0.55 where CD=f(M) perceptibly increases. The Drag Rise curve noticeably increases exponentially for all WWII wings but more so for the classic NACA airfoils with T/C in 23-30% range (compared to Mustang Low drag wing).

This is the single most important factor leading to superior high speed attainment with less Hp Available/weight and wetted area, in comparison to the other fighters in discussion

 

[Milosh]

A short pdf on airfoils, https://www.nasa.gov/sites/default/files/atoms/files/hallion.pdf

Why did the Germans use NACA airfoils when they had their own airfoil designs, Gottingen?

 

[Koopernic]

The leading edge of the wings of German fighter aircraft seem to be rounder/blunter than those of many other nation's planes (of course with exceptions). What advantages and disadvantages does it have?
Also their nose, i. e. the spinners seem not as pointed. does anybody know more?

The Claim that German aircraft had aerofoils that were thicker or had more rounded edges just isn't correct. The Fw 190 was the same or less than just about every American air force or naval fighter. This myth probably comes from ill-informed journalist banging on about the thin wings of the Spitfire.

I've assembled a list a list of representative aerofoils of various fighters.
The Incomplete Guide to Airfoil Usage

A note on reading the NACA 4 digit series:
The P-38 Lightnings outer wing was 4412 which means its point of maximum thickness was at 40% (first digit), its camber ie the distortion from symmetrical was 4% (second digit) and the thickness was 12% (last two digits. The P-38 actually had the more advanced 5 digit series on the inner wing 230016 which is read the same way with the 5th digit merely to distinguish. All these were developed by Eastman Jacobs at the NACA and were based on German aerofoils from the University of Gottingen developed during WW1. Jaccobs develoed the profiles used on Mustang. It was no one's idea at North American. Jacobs and Theodresen at the NACA deserve ALL the credit. NAA deserve the credit for having the balls to carry it through and the brains and preparation to do so.

The Researchers at the DVL at the University of Gottingen equal of the NACA developed a way of describing aerofoils and these modifiers are used in widely on aircraft such as the Viking, B-58 etc.

Kings of the inappropriately thick aerofoil were a group within the RAF or British Air Ministry who ruined several aircraft by imposing thick wings. The Hawker Typhoon for instance was a waste of its Brilliant Napier engine which Major Frank Hartford had gotten into service in less than 3 years, less than ½ the usual 6 years. The Typhoon made this most powerful engine almost a wasted effort. A simple NACA 5 digit aerofoil as used on the Corsair or Fw 190 would have turned it into monster. The Typhoon had to be developed into the Tempest with a Laminar Flow wing. The Germans had laminar flow wings flying on the Me 309 and BV 155, all their own work. The Me 262 and Arado 234 effectively had these characteristics.

Laminar Flow wings are in Bold.

• Vought V-166 F4U Corsair NACA 23015 NACA 23009
• Grumman G-50 F6F Hellcat NACA 23015.6 NACA 23009
• Grumman G-51 F7F Tigercat NACA 23015 NACA 23012
• Grumman G-52 F4F-7 Wildcat NACA 23015 NACA 23009
• Grumman G-58 F8F Bearcat NACA 23018 NACA 23009
• Curtiss P-40 Warhawk NACA 2215 NACA 2209
• Lockheed P-38 Lightning NACA 23016 NACA 4412

• Focke Wulf Fw 190 Wurger NACA 23015.3 NACA 23009
• 
  
• Supermarine 360 Spitfire NACA 2213 NACA 2209.4
• measured at the outer aileron hinge points, the detachable tips were about 7%.
• 
  
• Messerschmitt Bf 109E Emil NACA 2R1 14.2 NACA 2R1 11
• Messerschmitt Bf 109G Gustav NACA 2R1 14.2 NACA 2R1 11.35
• Messerschmitt Me 262 Schwalbe NACA 00011-0.825-35 NACA 00009-1.1-40
• Messerschmitt Me 155B NACA 2R1 14.2 NACA 2R1 11.35
• Messerschmitt Me 309 Laminar Flow Laminar Flow
• Blohm und Voss Bv 155 BVN 61. 2 34.3 15 BVH 61. 2 34.3 12
• 
  
• Boeing B-17 Flying Fortress NACA 0018 NACA 0010
• 
  
• Hawker Typhoon NACA 2219 NACA 2213
• Hawker Tempest H/1414/37.5 (14%) H/1410/37.5 (10%)
• Hawker Sea Fury H/1414/37.5 (14%) H/1410/37.5 (10%)
• 
  
• 
  
• Mitsubishi G4M1 Betty MAC118 mod (12.5%) MAC118 mod (10%)
• Mitsubishi G4M2 Betty Laminar flow Laminar flow
• Mitsubishi J2M Raiden Jack Laminar flow Laminar flow
• 
  
• Republic P-47 Thunderbolt Seversky S-3 Seversky S-3
• REPUBLIC S-3 AIRFOIL (s3-il)

• Republic XP-47F Thunderbolt NACA 66(215)-1(16.5) NACA 67(115)-213

(Note the XP-47F received the new 6 digit laminar flow series but the XP-72 did not.

• NA-102 P-51B Mustang NAA/NACA 45-100 NAA/NACA 45-100

The Germans decoded the P-51 NAA/NACA 45-100 aerofoil into their method of description.
P-51 NAA/NACA 45-100 airfoil graph

In German (or D.V.L.) this aerofoil is described (in five digits) as 1,6—50—13,6—0,825—39
1.) is 1.6 per cent maximum aerofoil camber
2.) maximum camber in 50 per cent aerofoil chord line
3.) maximum thickness
4.) radius (in per cent) of leading edge
5.) max. thickness is on 39 per cent of aerofoil chord

You can also use it to decode the Me 262 aerofoil.
Placed next to each other
P-51B 1,6—50—13,6—0,825—39
Me 262 NACA 00011-0.825-35 NACA 00009-1.1-40

Note, the Me 262 doesn't actually have NACA developed air foils. It used the NACA method of description with a modifier. NACA 00011 means it's a 11% thick aerofoil modified as per the trailing numbers.
Aerospaceweb.org | Ask Us - German Modifications to NACA Airfoils

 

[tomo pauk]

Useful tabulation of some of the wing data.
A nitpick - the F4U root was NACA 23018, not 23015. (diagram)
British listed the airfoil of the P-47 as 14% thick at the root.

 

[Shortround6]

The Hawker Typhoon for instance was a waste of its Brilliant Napier engine which Major Frank Hartford had gotten into service in less than 3 years, less than ½ the usual 6 years. The Typhoon made this most powerful engine a wasted effort.

This part of your post may be in error, I guess it depends on what is meant by "into service". Napier and Halford started work in 1935 or at least proposing configurations/basic layout. First prototype engine ran in Jan 1938. even if we allow that work started in Dec of 1935 that is two years right there. Sources differ on when it past a type test (Lumsden just gives 1939, wartime article in Flight says June of 1940. ) Prototype Typhoon first flies Feb 24th 1940 (4 years development?)
First squadrons get Typhoons in late 1941 (almost six years) and immediately run into trouble. It is not until the end of 1942 (and a change in management) that the Sabre becomes a reliable engine in service. 7 years?

The Sabre was at once both technically brilliant and a technical disaster. The concept and initial design may have been brilliant but exceeded the Company's ability to build, especially in quantity. The need to divert six Sidestrand centerless grinders from the P & W Kansas city plant (delaying manufacture of the "C" series R-2800 by 6 weeks) highlights the problem of designing engines you don't have the manufacturing base to actually build.

 

[Koopernic]

Useful tabulation of some of the wing data.
A nitpick - the F4U root was NACA 23018, not 23015. (diagram)
British listed the airfoil of the P-47 as 14% thick at the root.

You should let Ledicner know. It makes sense as this would make the Bearcat and the Hellcat the same. I suspect Wings may be thickened right near the interface to the fuselage to help with filleting and to fit an undercarriage, gun etc. It probably isnt aerodynamically significant.

 

[Shortround6]

Might have had something to do with the air intakes?

and with the landing gear going to the rear of the wing?

 

[drgondog]

The NACA/NAA 45-100 wing (for all P-51s), until XP-51F/G/H/J (NACA 66 series), were Modified by NAA/Ed Horkey team, from the NACA Low Drag (20% T/C) airfoil, to the wing on the P-51. They applied Theodorsen/Laplace transformations to derive the desired pressure distribution and CL, settling on 16.5% T/C at Root. What Did change between NA-73X/P-51 through P-51C was the LE Incidence - the D/K was different from C/L to WS 61.

The F4U wing was NACA 23018 -Root, 23015 - @wing fold, 8% T/C at tip.

Slight correction to NACA 4412 series.

The first digit is the maximum camber in % Chord, the second digit is the location of the maximum camber value in tenths of a chord. The last two values are the T/C as %chord.

The NACA 23012 is an expression for:
2% Camber
30% location of Max T/C
12% T/C

 

[drgondog]

A short pdf on airfoils, https://www.nasa.gov/sites/default/files/atoms/files/hallion.pdf

Why did the Germans use NACA airfoils when they had their own airfoil designs, Gottingen?

NACA airfoils were derivatives of many of the German WWI designs but into the 30's the NACA was leading the way in high Reynolds number wind tunnel experimentation/validations - notably in cambered and reflex cambered airfoils to investigate changes to CL and Pitching Moment CM as function of AoA.

 

[ChrisMcD]

The Sabre was at once both technically brilliant and a technical disaster. The concept and initial design may have been brilliant but exceeded the Company's ability to build, especially in quantity.

I agree totally.

According to LJK Setright, Napier had been "living hand to mouth for years" and a lot of the Sabre's problems were due to the fact that the production models could not compare to the hand built prototypes. Apparently their factory in London was full of antique lathes etc.