The continued problems of supply and the reliance on French engines continues to vex the War Office. British suppliers are simply not able to meet demand at present.
The latest development is the Hispano-Suiza 8a from Spain. The 8-cylinder water-cooled Hispano-Suiza first was first produced in prototype in February 1915. At this point rotary engines were already reaching their limits and the search for extra power was turning to water cooled inline engines. Unfortunately, early examples suffer from poor power to weight ratios compared to rotaries. The Hispano-Suiza owed its very high power to weight ratio to the employment of cast aluminium. Porosity problems with the aluminium were resolved by enamelling inside and out. Lubrication (employing pharmaceutical castor oil) was provided by a simple engine-driven vane type pump, located in the sump that circulated oil to all the components.
A number of French firms have contracted to build the engine under licence. Today Lieutenant-Colonel Brooke-Popham placed an order for 50 of these engines.