tomo pauk
Hello.
You once wrote that the airfoil of the Me 109 / Ki-61 had been obsolete and quite draggy. Could you tell where you have read that?
Dr Hoerner devotes an entire chapter analyzing the Bf 109. Chapter 14 "Fluid Dynamic Drag" - see pg 14-9 for tables of comparisons between Bf 109 and P-51 in which both CDt and CDw are ~ 2x over the Mustang..
Notably the 109 wing had smaller Thickness Ratio (14.2% Max T/C at root, 11.3% at tip vs P-51 w/16 % Max T/C Root and 12% for Mustang tip). All factors equal, it should have had less profile drag than the Mustang based on 'thinner wing' in velocity range below significant compressibility. RAF and LW concluded the same thing and were mystefied regarding the extreme lower drag values of the P-51.
We know that several factors were involved to reduce Total Drag of P-51 vs other period fighters. Such As - The fuselage design of employing 2nd order conics, imbedding rdiator/oil cooler into lower fuselage with intake aft of the wing lifting line, optimizing 'scoop/gutter' to peel BL effect at intake entry, 'interior plenum design forward of radiator/intercooler to improve the more gradual reduction of flow to the radiators which achieved lesser boundary layer separation and more equal pressure distribution on front face, the variable exit door controlled by coolant temps achieving a degree of Meredith 'effect' to reduce cooling drag.
Last but most definitely not least was the superior low drag/high speed airfoil and outstanding surface quality management of the wing.
Back to the 109.
Perusing through the 109 analysis I did not find a correlative CDparasite vs RN for the wing only, but did find CDwing was 37.5% of total CD of the entire airplane,
He states that for total wing CD for the 109 - incl. profile and friction and surface imperfections - equaled 37.5 % of the total CD.
The Total CD includes the wing CD, the iterference drag, the CD for fuselage, empennage, cockpit, radiator (incl pressure drag), carb intake plus the induced drag.