More on the Hornet installation:
The DH 103 Hornet, as one of the smallest twin-motor aeroplanes in the world, presented quite a problem in accommodating its power plants in the airframe.
To meet the problem, the supercharger air intake was extensively modified and the 130 and 131 were the first Merlins to incorporate down-draught induction systems. To eliminate the air scoop as used on the Mosquito, ducted air intakes were faired into the leading edges of the wings. The coolant pump was also moved from the bottom of the motor to its starboard side, and these modifications resulted in a bottom cowling line free from excrescences and of symmetrical form-an ideal arrangement for a high-performance fighter.
The engines were mounted low to obtain a smooth airflow over the wing, exhaust ejection below the wing, a short chassis leg below the nacelle for easy stowage when retracted, and the best possible pilot's view.
Propellers rising inboard were tried first as being preferable for fore-and-aft stability, but they blanketed the rudder at low speeds and rendered it ineffective for correcting swing on the ground. Propellers rising outboard were therefore adopted and the stability standards secured by tail plane dimensions and stability weights.
So not just the Twin-Mustang had to swap handed engines side to side.
[info from here which also discusses the Peregrine installation in Whirlwind]
Also attached is the Mossie nacelle for comparison.
