Looks like Katyusha can be won

http://warthunder.com/en/news/4687-v...om-katyusha-en

From 6th of May use the promo code KATYUSHA and activate it on the website
↓
When you enter the game you will receive Katyusha’s fellow warrior - the BM-8-24 rocket tank for an hour
and a special title "Incinerator"
↓
During this time destroy 5 enemies in one battle whilst driving BM-8-24.
You already own the BM-8-24? Then you have an unlimited number of attempts
↓
Receive your Katyusha for completing the task!

You may activate the code once every 24 hours (between 11:00 GMT and 11:00 GMT on the following day).
You will be able to activate the code a total of 4 times.
The BM-8-24 as well as other vehicles from the Allies will be available at a 30% discount during the whole event!
Attention! Only players, who have reached rank 3 in any nation may participate
Special conditions may be changed!
Need to get 5 kills in one game in one hour to get it for free

Ouch