I ran that mission a week ago.. 4x vultures and the target in an FDL. I took my Corvette in solo, tanked ( ignored ) the vultures and popped the FDL. Jumped out before the Vultures could break my last shield ring ( 10k MJ effective shield ). It was close, and I had to pop two 7A SCB's. But, Mission success and I collected a pretty good payout. I bailed on taking out the pack of vultures.. taking on all of them is ROUGH without a wing. A really good wing.
I hear you on the mission being matched to your wing and skill level, I learned the hard way as well... But it's more matched to your local rep level. If they like and trust you, they'll give you better payouts and harder missions. Remember to read the description.. that wing warning was the games way of letting you know it's gonna be a rough one.. The Vette was a good choice.. it's a heavy hitter. BUT... it's also got a huge hit box ( very large target ). The smaller ships will dance around cutting you to ribbons while the FDL blasts thru the pack for crippling alpha strikes. If you concentrate on one, the vultures are tough enough to last a few passes and the others will have a field day. The mission is almost a custom made death trap for a single large ship.
Don't think you're alone in getting blown out of the sky in a Corvette. Happened to me in a HazRES 30 minutes after I first purchased one. I thought I was a Lord of War, bit off more than I could chew.. and earned a trip to the rebuy screen for my hubris. After serious work engineering it.. the difference is night and day. Handles better, shields last much much longer, and the weapons hit a lot harder.
I suggest ....
Heavy Engineering : What is your Vette running ? You need a good 4500mj shield, with 50% resistances, a few SB's, a good SCB, and armor ( with the same resistances ). A bi-weave shield won't work here because you won't be able to recharge it, you'll be under sustained fire the entire time. Weapons are your choice, but I prefer two huge beams ( LR w/ thermal vent ), two small LR beams, and the rest OC'd MCs ( the large one with corrosive ). If you're good with fixed weapons, maybe an all PA/Rail build and a brutal Alpha Strike to the main target on the first pass, and the second one should finish him.
Your wing mates will need to be heavily engineered as well. Cobras will work, but they'll need to be finely tuned. A Vulture will outgun it ( Cobra III = 2M + 2S, Vulture = 2L weapons ). A vulture also has a bigger shield ( class 5, versus the Cobra class 4 ). Vultures are small, but also a combat specific ship. Cobras are multi-role.. so...
coriolis.io is your friend, experiment with builds.
Communication : You'll need to be able to communicate between each other, so you can all concentrate on the main target, then the secondaries. Do you use voice or txt chat ? Voice is loads easier in the heat of combat.
Coordination : You need a plan. IE : Jump in, everyone hits the main target together quick.. or the Vette and a Cobra hit the main target, and the other Cobras both target a single vulture and try to kite the others. Group Focus Fire is imperative or you'll just be an armed mob. Those Cobras won't last against Vultures for long, working together is their only hope. You HAVE to pop one Vulture and the FDL fast. Or split them up. Allowing all five/four to focus on one of you is going to be bad for the one chosen. Unless it's the Vette, it can tank for a bit. But even the Vette won't last forever ( as you discovered ).
Tactics : You need to drop the number of enemies FAST. Hitting the main target is a good first step. Once he's gone, focus on the next one together. Remember, if you can't take fire from 4 or 5 enemies, neither can they, and they're in smaller ships ( once the better shields are gone ). If one of your group drops shields.. RUN. A Cobra can outrun a Vulture, and if possible, kite any pursuing enemies. If the Vette drops shields, it should still be able to tank a while longer with good armor and HRP/MRPs. With luck and some skill, you should be able to take out the FDL and one vulture pretty quick. Once thats done, their damage potential has taken a good hit and mopping up should be a good bit easier.
Or you could all just mob-gank the target and jump out like I did. Good luck, and PM me and I'll see if I can join with your wing next mission.