Interpreting certain German airfoils

[s.flying]

Does anyone know how to interpret certain German airfoils like the ones from Heinkel, Blohm Voss and Arado?

Here's an example

Heinkel He 177
Wing Root: He 1.5 36.8 17.3-0.715-36.6
Wing Tip: He 1.5 36.8 10-0.715-36.6

Arado Ar 234
Wing Root: Ar 1.267 20 13-1.1-35
Wing Tip: Ar 1.227 20 10-1.1-30

 

[Snautzer01]

Try:

https://www.google.nl/search?q=airf...rd=cr&ei=FSuMVPbzNYXBPPvIgdgL#q=naca+airfoils

 

[s.flying]

Okay, i think i figured this out.

The Arado Ar 234 airfoil (Ar 1.267 20 13-1.1-35/Ar 1.227 20 10-1.1-30) is basically a NACA 12013 (Root) and NACA 12010 (Tip) with modifications to the first digits (theoretical optimum lift coefficient). The last four digits after the dashes are standard German modifications applied to a several dozen of NACA airfoils.

Would like to hear your thoughts on this.

 

[Simon Thomas]

He 1.5 36.8 17.3-0.715-36.6

1.5 - Depth of camber, percent
36.8 - Distance of maximum camber from leading edge, percent
17.3 - Thickness ratio, percent
0.715 - Nose radius, percent
36.6 - Backward position of maximum thickness from nose, percent

From NACA TM 1240 https://digital.library.unt.edu/ark:/67531/metadc65415/m2/1/high_res_d/19930090916.pdf

My WAG is that by the time this nomenclature was in use, the Germans had moved away from modifying the NACA 4 and 5 digit series and were developing their own aerofoils.

 

[Aeroweanie]

Very overdue, but the answer is: this provides a means of creating NACA modified 4-digit airfoils using a method developed by the AVA in Germany. These airfoils are uniquely described by the six numbers of their designations:

• The first number indicates the maximum value of the mean-line ordinate (also called the "camber"), in percent of the chord.
• The second number indicates the distance from the airfoil leading edge to the location of the maximum camber in tenths of the chord.
• The third number indicates the section thickness in percent of the chord.
• The fourth number indicates the leading edge radius parameter. The normal NACA 4-digit leading edge radius is designated by a value of 1.1.
• The fifth number indicates the position of maximum thickness in tenths of the airfoil chord.
• The sixth number indicates the trailing edge angle parameter.

Sometimes, these airfoils are given without the last two numbers. In this case, the checkbox can be clicked on and the display will change to this format. The fifth number will be assumed to be 30 and the NACA 4-digit modified expression will be used for the sixth number.

Thus, an airfoil designated "NACA 1.8 25 14-1.1 30/.50" has 1.8% camber, at 25% of the chord from the leading edge and is 14% thick. The leading edge radius is 1.1 times the thickness to chord ratio squared, the position of maximum thickness is now 30% of the airfoil's chord and the trailing edge angle is 2 * arctangent(.5 * t/c). A designation of "0012-.55" indicates that the camber is zero, so the remaining terms are not listed.