Armstrong Whitworth F.K.9

Quadruplane Reconnaissance Fighter Prototype

United Kingdom | 1916

"The Armstrong Whitworth F.K.9 successfully sold the Royal Flying Corps on the idea of a quadruplane fighter - this was realized in the F.K.10 series."

Authored By: Staff Writer | Last Edited: 09/08/2022 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site; No A.I. was used in the generation of this content.

There proved plenty of experimentation with multi-winged aircraft designs during World War 1 (1914-1918). The biplane was more or less the standardized fighter/bomber form while some monoplane fighters did go on to see considerable time in the air. Triplanes managed a short, though useful, revolution but quickly fell out of favor. Beyond these categories was the "quadruplane" - four-winged arrangement intended to harness the agility and control offered from use of four parallel planes in the wing structure, this providing for exceptional lifting and turning properties, qualities critical to close-in dogfights. Several firms of the period experimented with such types but many fell by the wayside as being much too impractical for military service.

Armstrong Whitworth of Britain tried its hand at a quadruplane in the form of the FK.9. It was a two-seat, single-engine form intended for reconnaissance and fighter duties. Development was through private venture in the hopes of interesting the Royal Flying Corps on the design. Its offshoot, the FK.10, would become one of the few quadruplane designs of the war to be adopted form formal service.

First-flight of a prototype FK.9 was had in the summer of 1916 and changes were instituted to remedy several issues: the engine cowling was completely reworked and the tail fin given greater surface area. All-new wings were added and these carried larger-area ailerons as well. The undercarriage track was made wider for improved ground running. Power was served from a Clerget 9Z rotary engine of 110 horsepower driving a simple, two-bladed wooden propeller in the nose. The crew of two sat in tandem across two open-air cockpits, these positioned aft of the four horizontal planes cranked forward. Standard armament was 1 x .303 Vickers machine gun in a fixed, forward-firing emplacement operated by the pilot and 1 x .303 Lewis Gun managed from a trainable mounting by the rear gunner / observer.

The FK.9 was officially evaluated at the Central Flying School during November and into December of 1916. It proved worthy enough to warrant a serial production contract for fifty aircraft - though improvements to the design necessitated the change in designation to "FK.10" for these mounts.

A single FK.9 aircraft was built followed by just 8 x FK.10 - the 50-strong order never fulfilled due to the design's heavy drag. None saw combat service in the whole of the war.

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Power & Performance
Those special qualities that separate one aircraft design from another. Performance specifications presented assume optimal operating conditions for the Armstrong Whitworth F.K.9 Quadruplane Reconnaissance Fighter Prototype.

1 x Clerget 9Z rotary engine of 110 horsepower driving two-bladed propeller at nose.
Propulsion

84 mph
135 kph | 73 kts
Max Speed

9,843 ft
3,000 m | 2 miles
Service Ceiling

211 miles
340 km | 184 nm
Operational Range

455 ft/min
139 m/min
Rate-of-Climb

City-to-City Ranges
Operational range when compared to distances between major cities (in KM).

NYC

LON

PAR

BER

MOS

TOK

SYD

LAX

NYC

Structure
The nose-to-tail, wingtip-to-wingtip physical qualities of the Armstrong Whitworth F.K.9 Quadruplane Reconnaissance Fighter Prototype.

2
(MANNED)
Crew

22.2 ft
6.78 m
O/A Length

27.9 ft
(8.50 m)
O/A Width

11.5 ft
(3.50 m)
O/A Height

1,246 lb
(565 kg)
Empty Weight

2,039 lb
(925 kg)
MTOW

Design Balance
The three qualities reflected below are altitude, speed, and range. The more full the box, the more balanced the design.

RANGE

ALT

SPEED

Armament
Available supported armament and special-mission equipment featured in the design of the Armstrong Whitworth F.K.9 Quadruplane Reconnaissance Fighter Prototype .

1 x .303 Vickers machine gun in fixed, forward-firing position over the nose, synchronized to fire through the spinning propeller blades.
1 x .303 Lewis Gun on trainable mounting in rear cockpit.

Variants
Notable series variants as part of the Armstrong Whitworth F.K.9 family line.

F.K.9 - Base Series Designation; single prototype completed.

Operators
Global customers who have evaluated and/or operated the Armstrong Whitworth F.K.9. Nations are displayed by flag, each linked to their respective national aircraft listing.

Total Production: 1 Units
Contractor(s): Armstrong Whitworth - United Kingdom

[ United Kingdom ]

Relative Max Speed

Hi: 100mph

Lo: 50mph

Aircraft Max Listed Speed (84mph).

Graph Average of 75 MPH.

Era Crossover

Showcasing Aircraft Era Crossover (if any)

Max Alt Visualization

Production Comparison

1

36183

44000

Entry compared against Ilyushin IL-2 (military) and Cessna 172 (civilian) total production.

MACH Regime (Sonic)

Sub

Trans

Super

Hyper

HiHyper

ReEntry

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Aviation Timeline

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WWI

Interwar

WWII

ColdWar

Postwar

Modern

Future

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Image from the Public Domain.

Mission Roles
Some designs are single-minded in their approach while others offer a more versatile solution to airborne requirements.

AIR-TO-AIR COMBAT

RECONNAISSANCE

X-PLANE

Recognition
Some designs stand the test of time while others are doomed to never advance beyond the drawing board; let history be their judge.

Military lapel ribbon for the World War 1

Going Further...
The Armstrong Whitworth F.K.9 Quadruplane Reconnaissance Fighter Prototype appears in the following collections:

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