'corse it can. It's just that the operational fit requires all sorts of dangly bits with all their drag. Take them off and it's just a draggy F3. F3 could do it easily (even with some of it's draggy bits and the GR certainly can. Is it realistic? Well, yes. If you've done your mission and you need to escape (and you have the fuel) it's completely practical to clear the wings and run. The engines aren't that different and the airframe on the GR is only slightly draggier (what a great word!)