 This differed in having a conventional fixed tailwheel undercarriage, a non-gulled upper wing and was to be powered by a 450 hp (336 kW) Pratt & Whitney Wasp Junior engine.These aircraft were to be assembled in secret by the Belgium company LACEBA (Les Ateliers de Construction et d'Exploitation de Brevets Aéronautiques).Flight testing in Belgium was carried out with a 280 hp (209 kW) Salmson 9ABa engine, to give the impression that the aircraft was a trainer rather than a fighter, with the more powerful engine to be fitted when the aircraft was delivered to Spain.