That's pretty expensive: 8 Russian fighter jets is probably about $100-200 million.People have probably already heard about the Ukrainian strike on Russia's Saky airbase in occupied Crimea.
There's a pretty incredible before-and-after satellite photographic slider here;
Russian warplanes destroyed in Crimea airbase attack, satellite images show
Multiple aircraft at Saky base in Crimea blown up, with the new evidence suggesting possibility of targeted attackwww.theguardian.com
Satellite images were taken 4 hours before the attack, and then the next day. They confirm 8 Russian aircraft were destroyed in the strike. This vitally shows that Ukraine is able to utilise long-range missile artillery, and is able to bypass Russian air defence.
Although Ukraine has not confirmed a missile strike: there is a suggestion that it was partisans or special forces who may have got close enough to fly explosive drones into the ammo/fuel stores.