OK, I read that book.
https://amzn.to/2EG3NwN
Unfortunately, it does not add much to the information about Su-2 development and its deployment in 1941-1942 besides what was published already since early 2000s. Statistic data is patchy, poorly arranged and without attempt to make serious analysis... well, this is typical issue of many Soviet and post Soviet military publications. Not the best work of D.Khazanov, unfortunately.
On the bright side, there is detailed narrative of pre-war history of Su-2 and prototypes and interesting (yet not systematized) records of combat operations.
Below is the information which I find interesting in the context of this thread.
1. In 1941.
Three regiments in Zapadny (Western) regional command. June 21st, 1941: 75 aircraft and 126 crews available, just 25 crews "ready for combat".
Extremely intensive operations end June-early July 1941. Probably the most intensive among all bomber types except SB. Up to 40 and more flights per day. Some regiments have lost all aircraft and were withdrawn to the rear after 10-15 days. Exception: Odessa region where Su-2 were used rarely until middle of July when enemy forces began to cross Dniester river.
2. Production in war time.
Problems started in July 1941 after evacuation of Zaporozhye factory (one of three producing Su-2). Two other factories (Kharkov and Dolgoprudnensky) were relocated in October 1941. Before that, Kharkov's production was already limited because all stock of M-89B engines was taken out and shipped to Komsomolsk-on-Amur (Far East of USSR) for DB-3F bombers.
Attempts to resume production in new place (Molotov) began in November 1941. The plan was to create new large factory on the base of equipment of several plants relocated from the occupied territories. Apparently, good idea at the wrong time and wrong place. Lack of equipment (delayed and lost during relocation), deficit of workforce (less than 50% of required)… To make things worse, M-82 engine blueprints were lost during transportation.
GKO (State Committee of Defence) held the conference on 19th November 1941 and issued the resolution with two main points:
a) M-82 engine to be installed only on TB-7, project 103 (future Tu-2), IL-2 and DB-3F.
b) Factory in Molotov to stop all works related to Su-2 and to start production of IL-2 with M-82 engine. (Later the factory was allowed to complete production of small batch of Su-2 from the kits and spare parts already in the stock).
Results of this resolution?
TB-7(a.k.a. Pe-8). Adaption for M-82 took several months. Test flights began only in April 1942 and completed in October 1942. Just one Pe-8 with M-82 was produced in 1942.
DB-3F. After all tests and trials in 1942-1943, M-82 engine was not accepted.
Project 103 (Tu-2). 80 airplanes were produced in 1942 before all works were stopped by another resolution of GKO. Resumed at the end of 1943.
Il-2 with M-82 engine. Blueprints were not ready until end of December 1941. Trials began on 20th Feb 1942. Ordered in production 28th Mar 1942. Ordered to stop production and to give remaining stock of M-82 engines for the LaGG fighters modernisation – 26th Apr 1942.
5. About losses.
66th Division reported numbers of flights per combat loss in 1941: Pe-2 - 32, SB - 8, Su-2 - 71.
2nd Army close air support aviation (1 regiment of Su-2 and 3 regiments of IL-2) statistics during German offensive near Voronezh, summer 1942, total/serviceable:
27th June. IL-2 53/36. Su-2 26/16.
01st July. IL-2 41/11. Su-2 22/14.
270th Division attrition rate in Jul-Aug 1942, flights per total loss (all reasons): Su-2 – 80, Pe-2 – 20.
Reserve regiments and training centers in 1941-1942: Su-2 safety record was 25%-30% (in terms of flights per accident) better than of Pe-2 and IL-2.
6. Trivia.
Total production: 893 according D.Khazanov or 910 according to Sukhoi Company. In service until January 1944.
Su-2 and Curtiss O-52 were the only artillery spotters of VVS in 1942-1943 (not counting less successful attempts with Yak-7) . When number of Su-2 dwindled, the only replacement available was IL-2 and it was not ready for that role.
M-82FN engine which brought success to La-5 fighter in 1943, have been tested by Pavel Sukhoi team on Su-2 extensively during summer 1942.
Not less than 7 different engines were tested on Su-2 in 1941-1942 besides already installed (M-87B, M-82, M-88(B)) on airplanes in operation. So, while denied from the further production, the type served as "a flying laboratory".
I wish we have more data from archives to make comparative analysis of operational effectiveness of Su-2 and IL-2. Until then, I refrain from final conclusions.