The F-15A 'Eagle' is a single-seat variant; powered by two new Pratt & Whitney F100-100 Axial compressor turbofan engines with afterburners mounted side-by-side in the fuselage, which achieves a combat thrust-to-weight ratio in excess of 1:1. Visibly, the F-15 has a unique feature vis-a-vis other modern fighter aircraft: it does not have the distinctive turkey feather aerodynamic exhaust petals covering its engine nozzles. This is because the petal design on the F-15 was problematic and could fall off in flight; therefore they were removed, resulting in a 3% aerodynamic drag increase.