(70-90 per turn)
At least initially, they are almost always higher, the last turn I checked had 235 training losses, but that might be due to increased losses in my version.
I see your really a glass half empty guy.
No, I'm just trying to make sure you don't fall into the all too common mental trap of "what I've destroyed is enough to hurt the Soviets". You really need to destroy more Soviet aircraft to make an impression.
My production estimate was based on the initial production, so for 49 turns it's much too low. At the start of the 1941 campaign, the Soviets produce 263 aircraft per turn. At the start of the 1942 campaign, they produce 719 aircraft per turn. The actual production in June 1942 will be slightly lower when you get there in a 1941-1945 campaign as all aircraft production starts maxed out in the 1942 campaign.
You can destroy 263 aircraft through bombing and intercepts, but destroying 719 isn't particularly likely unless the Soviets make some serious mistakes with their deployment.
For the Soviets, a war of attrition is a war they can win, and the losses you inflict on them just are not enough to turn the war in your favour.
As an aside, I'm getting some pretty decent results with my own air base bombing campaign (against the AI), but again only around 350-400 aircraft per turn, tops, at the moment, mostly due to how few bombers actually participate in the bombing missions and how few aircraft are actually destroyed. Currently, there seems to be no real direct relation between the amount of aircraft stationed at an air base and casualties from a bombing run, which is rather frustrating.