Nice
if you dig really deep, the Naca coding of the P 51 wing came post wing development. as i understand it both the spitfire and P51 did not use Naca developed airfoils.
Spitfire NACA 2213 root, NACA 2209.4 tip. For NA73X through P-51M NAA/NACA 45-100, for the XP-51F/G/J, P-51H and P-82 NACA 66-(1.8) 15.5
" wing thickness" yes it was a thick wing, had a lot to stuff in there, add to that the British air ministry's experiences with the P40 wing skins wrinkling in North africa, this information being passed on. so we could say the best thick wing around.
RAE/RAF had zero input to the development of the NAA/NACA 45-100 airfoil. No input regarding 'wrinkled skins' of P-40 wing. The Brits 'bought' NA-73 based on a.) their impressions of the high quality of the BT-9 and AT-6, b.) Commitment to adhere to the British Specification F.18/39 Operational Requirement O.R.73, and c.) because they were impressed enough with the Cooling system scheme of the P-509 to believe that it would actually work.
As to 'thick', yes relative to Spit, but 'thin' relatively speaking when compared to F4U (NACA 23018 root), Typhoon (NACA 2219), F8F (NACA 23018) - about the same P-38 (NACA 23016), FW 190 (NACA 23015.5), F6F (NACA 23015), P-39 (NACA 0015), P-40 (NACA 2215). To the P-40, same family as Spit but 2% thicker at Max T/C.
economical, MPG. the spit Mk IX was slower in transport, but that was when the aerofoils lift equaled the weight with no angle of attack as at the same speed the P51 had a heap of angle of attack, thus drag. the P51 needed another 30-40 mph to eliminate the angle of attack but still had a thick wing to push though. P51D
The first target for flight test for both range and endurance (slightly different locations on CD vs V plot), is where Induced Drag CDi = Parasite Drag Cdp. The best cruise range requires more power and speed than best endurance.
To your statement - Yes for given flight speed and altitude the Spitfire CL will be lower than Mustang because of greater wingspan and lower GW. Because that is true, it follows that at that speed and CL it will have lower Induced Drag CDi than the Mustang. What you miss here is that the Parasite drag of the Spitfire is quite higher than the Mustang. So, present sources please?
i didn't read back on what i wrote for the P51, and yes it didn't have a pich down as comparability formed at equal distance on both upper and lowered sides of the wing. every thing else is bang on.
?????? Mostly incoherent, but please elaborate>
BUT. the P51 had 3 profiles. Inner, mid section and tip. the tip had a bit more of a concave under skin to try and fix low speed handling, the inner section was quite sweeped back. the big advantages of this are not often talked about. i have read that this had a small part to play in the Valiants crescent wing design,
The root chord was 16.5% at C/L, straight taper to 9%. The tip airfoil was different. No concave 'under the skin'. The 'strake or crank' was not 'quite swept back' although the D was more pronounced angle to accomodate new wheel well door. Coversely the P-51H was straight LE. The 'big advantage' was to locate the main gear forward of the front spar.
Sweep? No. The spar was perpendicular to the C/L of airframe. The leading edge and trailing edge were straight taper to the Tip.
i have never found any information of transonic flight of the P51H or why this was illuminated in the H? although i would sagest its advantages were just not known at that time.
????? Essentially the same as D but shock wave becan slightly further aft of D wing section location