Designed by Nathaniel Barnaby,[1] the Royal Navy Director of Naval Construction, the hull was of composite construction; that is, iron keel, frames, stem and stern posts with wooden planking.

They were fitted with three boilers, a 2-cylinder horizontal compound expansion steam engine and a single screw.

Griffon and Falcon were engined by Laird Brothers and had a feathering propeller.

Flamingo and Condor were engined by John Elder & Co, and all ships had a designed 750 indicated horsepower (560 kW), developing about 11.5 knots (21.3 km/h) under power.

In 1884 Flamingo and Griffon were rearmed with two 5-in Vavasseur breech loaders replacing the 7-in muzzle-loading rifle.