Complex sentence: The open cockpit was under the trailing edge of the wing where there was a cut-out to improve upward visibility and had a long streamlined headrest which topped the fuselage as it tapered strongly to the tail.
Split into simpler sentences: The open cockpit was under the trailing edge of the wing where there was a cut-out to improve upward visibility. A long streamlined headrest topped the fuselage as it tapered strongly to the tail.