Blackburn Iris Mk III
Blackburn Aircraft · United Kingdom · first flew 1929 · transport aircraft
The Blackburn Iris was the RAF's largest biplane flying-boat of the late 1920s, a massive patrol and reconnaissance craft capable of long ocean cruises. The Mk III introduced uprated Rolls-Royce Condors and minor hull refinements over earlier marks.
Recognition (WEFT)
| W — Wings | High-mounted, straight |
|---|---|
| E — Engines | 3 × piston, wing-mounted |
| F — Fuselage | 20.4 m fuselage |
| T — Tail | Conventional |
WEFT is AircraftIQ's four-point recognition method — how it works.
Spot it by:
- Large biplane flying-boat with three Rolls-Royce Condor engines between the wings
- Open cockpit set high on a thick slab-sided hull
- Twin strut-braced floats under lower wingtips
The Iris Mk III is immediately distinguished by its three inline Condor engines mounted in tandem pairs between the broad biplane wings — a unique arrangement seen on no other type of the period. The deep, flat-sided hull sitting high on the water and the absence of wingtip floats in favour of strut-mounted pontoons clinch identification.
Specifications
- The Blackburn Iris Mk III has a length of 20.4 m (67 ft).
- It has a wingspan of 29.6 m (97 ft).
- Its maximum speed is 193 km/h (120 mph).
- Typical crew: 5.
Figures are for the representative variant described above; marks differ. See how AircraftIQ sources figures.
History
Blackburn designed the Iris to meet an Air Ministry requirement for a long-range maritime patrol boat, with the prototype flying in 1926. The Mk III was the definitive production form, entering RAF Coastal Area service from 1930. Only a handful were built, reflecting the small peacetime budgets of the era. The type was eventually superseded by the improved Perth variant.
Variants
Marks I and II used different engine fits; the Mk III settled on three Rolls-Royce Condor IIIBs in tandem push-pull arrangement between the biplane wings. The Blackburn Perth (Iris Mk V) was the enlarged final development.
Where you'll see it
Operated exclusively by RAF No. 209 Squadron from Felixstowe and later Mount Batten, the Iris undertook long-range North Sea and Atlantic patrols. All aircraft were retired by the mid-1930s and none survive.
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