Hi,
Thanks for this sort of info, I really appreciate it. I am almost totally ignorant on the subject, so bear with me if I ask some very basic questions :
1, Do you have some sorts of strenght breakdown, too? I mean something like
end of 43-Nov : zero Mustangs
end of 43 dec : say 100 Mustangs with operational units (all with 354th), 80 servicable
end of 44 feb : say 150 Mustangs with operational units (say 80 with 354th, 40 with 363rd, 30 with the 4th FG), 120 servicable in total
and so on ?
Yes - but they are 'approximate' - just like the availabilty of LuftFlotte Reich in that timeframe. The first thing to recognize is that the basic TO&E of the USAAF Fighter Group was 72 'authorized' but the truth is that few Mustang Groups had more than 60-64 in the inventory until May-June 1944.
The second thing is that the Mustang was very tempermentl in Dec-May, 1944, requiring usually 8-10 spares to manage to get three sqadrons of 16 a/c at the target. In Dec-Mar most were lucky to get 40 P-51's escorting primarily because of engine related mechanical problems - mostly plugs, manifold pressure and coolant.
That said - I spent a lot of time on this while trying to educate Soren on the 'realities' of overwhelming air superiority by Target Escort fighters in Dec 1943 through May 1944. Remember that P-47s had to stop along Bremen to Stuttgart axis and served as Penetration and Withdrawal Escort until the P-47M finally gave them the range to go all the way. Only the Mustang and Lightning units could go all the way.
So, as we said before 'let's do the math'
Dec-Feb 11, 1944 - one Group (354)60+ on the base, 30-40 over target plus 20th and 55th FG P-38 units with 30-40 each
Feb 11, 1944 - two Groups (354 and 357), slightly better reliability, 70-80 over target plus 20th and 55th P-38 units of 30+ each over different targets
Feb 23-26 - four Groups over Taget (354, 357, 4th, 363rd) 140 Mustangs over different targets plus the two P-38 Groups
March 8 to April 10 - five groups over Targets (4th, 357th and 355th - 8th AF, 354th and 363rd - 9th AF) - ~190-200 Mustangs over different targets to escort Three Bomb Divisions of 35+ Bomb Groups attacking 1-8 different targets - At this time the P-38 groups also had three full strength units (20th, 55th and 364th).
April 10- April 29 - six Mustang (4th, 352nd, 354th, 355th, 357th and 363rd)and three Lightning groups over Targets - reliability up so each Mustang and P-38 group effectively averaged 40+ each at the target, P-51s slightly higher - P-38's slightly lower. The 479th FG came into ops as fourth and last P-38 group in 8th AF in early May
The 339th flew first missions as Penetration or withdrawal support from April 30 forward to mid May and the the 361st and 359th FG came into ops in mid May as the 354th and 363rd returned to 9th AF control in prep for D-Day.
So May had the same basic Constituency of six Mustang groups getting now closer to 45-48 ships each at the target for 270-288 Mustangs plus 200 Lightnings deep into Germany. It was in mid May that the 15th AF started coming on line with Mustangs.
May through September is the major conversion period in which every 8th AF FG except 56th, 78th, 353rd and 356th. The 78th, 353rd, and 356th converted in Oct-Dec 1944 to raise the number of Mustang Groups to 14. In October - rest of war each Fighter Group could and would put 60+ Mustangs in the air over target. This is the period in which large forces of Mustangs were flying at least three Sweeps out in front of Escorts looking for GAF fighters trying to form up and disrupt them - often with numerical advantage over the German fighters when they found them.
Hope this helps sort it out.
Basically what I am trying to achieve with these sort of data is to establish how availibilty and performance related.. quantity vs. quality, does the plane has both? I am trying to avoid fixation on rare, best variants (obviously the Mustang isn`t such) if at the given date would be available only in limited numbers, introduction of the Me 262 and P-51D in the summer of 1944 comes to mind... they are 'contemporaries', only that one has the numbers to make it`s performance felt in the air, the other doesn`t.
The variants for December were the P-51B-1 and -5 followed in January. The P-51B and C variants came into inventory as -5 and -7 in March timeframe along with factory installed 85 Gallon Tank plus start of field modification Malcolm Hood. In March the P-51 suffered troubling engine mount failures (inadequate heat treat - and quickly replaced) plus a couple of wing and tail failures traced to the uplocks failing on the main gear door causing the landing gear to drop at 450-600IAS with catastrophic results. Uplock kits and intro of P-51D in June solved that problem. The P-51B-10s and -15s arrived in April timeframe.
The P-51D-5 arrived in the late May, the P-51D-10 with tail strake and re-inforced tail mount structure arrived in July to solve (mostly) high speed yaw issues of new bubble canopy version. The 51D-20 with tail warning radar came into play in February time as well as first P-51H production models in US.
2 What`s the importance of being issued to the 9th, I though the 8th Strategic and 9th Tactical were on the same side of the fence.

Or did the Army Air Force think different at the time...? Did the 9th strictly operated against targets in France or...?