The Excalibur was designed as "clone" of the
Quad City Challenger II aircraft. The company took the basic Challenger design and incorporated many changes, including mounting the engine upright allowing larger
propellers and the
Rotax gearbox to be mounted, lengthening the tailboom and enlarging the tail vertical surface to increase stability, shortening the
ailerons and replacing control cables with torque tubes. The optional
Dacron covering on the Challenger was replaced with
Superflite standard aircraft fabric, the fuselage was lengthened to give more backseat room and the nosecone was reduced in size to provide better over-the-nose visibility. The design was also streamlined to reduce drag and round cross-section wing
struts were replaced with aerodynamic extrusions. The Challenger's rigid landing gear was replaced with a
bungee-suspended system. Regarding the landing gear improvements reviewer Andre Cliche, author of the Ultralight Aircraft Shopper's Guide, said: ==Variants==