Bf109 Airfoil

[swampyankee]

According to The Incomplete Guide to Airfoil Usage, the Bf109 used a NACA airfoil, the 2R1 14.2. Anybody have any data, i.e., polars and coordinates, for this airfoil?

I really don't want to compile my copy of FLO-22 (yep, I've got it) because it's on a 3.5 in floppy, and I would need to buy a drive.

 

[Wurger]

NACA 2R1 14.2 wingroot airfoil and the NACA 2R1 11 wingtip one for the Bf109B to Bf109 E.

NACA 2R1 14.2 for the root and NACA 2R1 11.35 for the tip for the F through K models.

 

[Simon Thomas]

Sorry to bring this up from the distant past, but when I searched for a NACA 2R1 aerofoil, this was the first hit and it didn't have the answer. After further digging I found a source for the aerofoil. It is found in NACA Technical Report No. 460, relevant sections copied below.

It is a NACA 0012 with a 2% camber in Glauert's format.

I tried to extract the camber but the camber line from the co-ordinates for the first 2/3 points from NACA TR460 were not matching the Glauert cubic equation nicely.

It will need scaling to suit the Bf109 thicknesses.

 

[Koopernic]

The NACA 4 digit series were developed by systematic variation by Eastman Jacobs. They were inspired by the German Gottingen Go series, the first modern thick wing airfoils. Eastman Jacobs then went on to develop the NACA 5 digit series by systematic variation of the upper leading edge, these gave slightly higher coefficients of lift and L/D ratio at the expense of slightly inferior stall characteristics.

The Germans used both the NACA 4 and 5 and the allies used the Go (Sunderland flying boat, Sterling). The Germans developed a way of describing the modifications of the NACA series (those 2R numbers) which were then copied by the NACA. EG the B-58 Hustler airfoil.

Willy Messerschmitt developed improvements to airfoils that gave them good pitching characteristics and improved aircraft stability and stall characteristics, his academic fame probably rests on that.

Eastman Jacobs went on to develop the NACA 6 series laminar flow series of airfoils and those of the P-51. These were the first ones to be developed by formulae rather than systematic tests in a wind tunnel. Jacobs airfoils had good transonic and supersonic characteristics and he was developing a supersonic aircraft called Jakes Jeep. It used a motorjet. This is why the Bell X1 had straight wings.

When he found out about the Turbojet in 1943 and that the NACA had been kept out of the loop by USAAF it broke his heart and he quit and opened a seafood restaurant. The Bell air comet was probably a failure because of a lack of involvement by Jacobs.

 

[Simon Thomas]

The question about Fighter NACA profiles led me to re-think about the Bf109 aerofoil.
I obtained from ebay some electronic copies of Bf109 information, including of a drawing that showed the aerofoil.

The drawing was this one:

I have no idea if this is correct and/or genuine.

What I found interesting was that when I overlaid the 2R112 aerofoil co-ordinates from the NACA TR 460 and the mapped the co-ordinates from drawing, I found this:

There is quite a difference between them. I compared them with the NACA 2412, M6 and the RAF 34 and found them all to be there or thereabouts.
It is evident that the Bf109 aerofoil is not identical to 2R112. The 109 designer must have made changes to the base aerofoil to suit the requirements of the 109.
The similarity with the other aerofoils makes me wonder if the NACA 2R112 is indeed the base aerofoil.

 

[Snautzer01]

Thats because the drawing hasnt the function of representing the airfoil.

 

[Snautzer01]

Come to think of it, i might have something. Will look.

 

[Snautzer01]

 

[Snautzer01]

 

[Simon Thomas]

Finally figured this one out.
I used the airfoil dimensions from here:

and here:

and determined the dimensions of the first 40% of rib one.
I extrapolated the entire aerofoil to match the drawing:

I found that the 109 airfoil is a NACA 2R1 with the thickness scaled to suit (14.2% at Rib 1 and 11.35% at Rib 13) and the first 80% of the airfoil camber is scaled to be 2% instead of 4.6%. The camber of the last 20% of Rib 1 diverges significantly from the 2R1.

 

[Aeroweanie]

To add to this discussion, here is the Bf 109G wing loft, as obtained from the files of Avia, which built them: Avia wing loft.pdf

 

[ThomasP]

Excellent find, thanks Aeroweanie.

 

[Aeroweanie]

For what its worth, I've always relied on these drawings:

 

[Snautzer01]

For what its worth, I've always relied on these drawings:
View attachment 724198View attachment 724199

See post #8

 

[Simon Thomas]

Thanks Aeroweanie for that loft information.
I compared the wing loft Rib 1 dimensions to my calc. My lower surface at 0.9 to 1.0c was a bit off, hence the wonky camber.

It's good to know that the drawings are very accurate.