The Eagle DW-1 is an unusual and rare aircraft, and this is what makes it an ideal subject for a scale model! Designed around the O.S. 1.6 FX engine, though it could easily be made for electric.
Spanning nearly 2.8 Metres, this will be an impressive model any flying field you attend! The plan consists of four large sheets, and includes all templates, including the canopy mold.
If this is too large for you, get in touch and we can work up a smaller version for you.
Eagle Aircraft DW-1 – Design, Development, Production and Performance
The Eagle Aircraft DW-1 is an American single-seat agricultural biplane designed specifically for aerial application of fertilisers, herbicides, pesticides and seed. Designed by Dean Wilson in the mid-1970s, the DW-1 departed from conventional agricultural aircraft by combining a high-aspect-ratio biplane wing with modern aerodynamic features intended to improve efficiency, payload capability and low-speed handling. It entered production in 1979 and remained in production until 1983, with approximately 95 production aircraft completed, although some sources cite up to 136 airframes including aircraft completed under subcontract arrangements.
Origins
During the 1970s, most agricultural aircraft were either:
- low-wing monoplanes (such as the Air Tractor series), or
- traditional radial-powered biplanes such as the Grumman Ag-Cat.
Designer Dean Wilson sought to combine the advantages of both configurations by developing an aircraft that offered:
- excellent low-speed lift
- reduced induced drag
- lower operating costs
- improved manoeuvrability
- greater chemical payload
- simple maintenance
Rather than copying earlier agricultural biplanes, Wilson incorporated ideas drawn from high-performance sailplanes, particularly in the design of the wings.
Development
The prototype first flew in 1977 at Boise, Idaho.
Initially the aircraft flew with a:
- Jacobs R-755-B2 seven-cylinder radial engine.
Early production aircraft were then offered as the Eagle 220, powered by a 220 hp Continental W670 radial engine. Operators soon preferred greater power, leading to the introduction of the Eagle 300, fitted with a 300 hp Lycoming IO-540 flat-six engine. The Lycoming installation offered improved climb performance, lower maintenance requirements and better fuel economy, and it became the dominant production configuration.
Design Philosophy
The DW-1 was developed around several design objectives:
- maximise lifting capability
- minimise stall speed
- improve spraying accuracy
- provide excellent pilot visibility
- simplify maintenance
- reduce structural weight
Unlike many agricultural aircraft, the emphasis was on aerodynamic efficiency as much as payload.
Airframe Design
Wing
Perhaps the DW-1’s most distinctive feature is its high-aspect-ratio biplane wing.
Unlike earlier agricultural biplanes with relatively short wings, the DW-1 employed long, tapered wings inspired by sailplane design.
Characteristics include:
- wooden wing structure
- fabric covering
- high aspect ratio
- tapered planform
- staggered biplane configuration
The design produced:
- lower induced drag
- excellent lift
- low operating speeds
- reduced chemical drift
- improved climb with heavy loads
One particularly unusual feature was the use of spray booms integrated into the trailing edge of the lower wing, reducing drag and improving chemical distribution.
Roll Control
The DW-1 incorporated an uncommon control system.
Instead of relying solely on conventional ailerons:
- the upper wing carried ailerons, while
- the lower wing employed spoilers on its upper surface.
This arrangement improved roll response while simplifying the lower-wing spray boom installation and reducing adverse yaw.
Hopper
The chemical hopper was mounted immediately ahead of the cockpit and close to the aircraft’s centre of gravity.
Capacity:
- approximately 946 litres (250 US gallons / 208 Imperial gallons)
Typical loads included:
- liquid fertiliser
- herbicides
- pesticides
- fungicides
- seed
Locating the hopper close to the centre of gravity minimised trim changes as the load was dispensed.
Fuselage
The fuselage consisted of:
- welded steel tube cockpit structure
- aluminium skinning
- easily removable inspection panels
- corrosion-resistant finish
The compact structure was intended to withstand the demanding operating environment of agricultural aviation, including repeated low-level manoeuvring and exposure to corrosive chemicals.
Cockpit
The enclosed single-seat cockpit provided excellent visibility over the nose and toward the spray swath.
Typical equipment included:
- conventional flight instruments
- engine gauges
- spray control system
- agricultural GPS (later retrofits)
- radio
- ventilation and heating
The elevated seating position gave the pilot an excellent view during precision application work.
Landing Gear
The aircraft employed a conventional tailwheel undercarriage with:
- fixed main gear
- large low-pressure tyres
- steerable tailwheel
Advantages included:
- high propeller clearance
- suitability for rough farm strips
- low maintenance
- structural simplicity
Powerplant Development
Prototype
- Jacobs R-755-B2 radial engine
Eagle 220
- Continental W670-6N
- Seven-cylinder radial
- 220 hp
Eagle 300
- Lycoming IO-540-M1B5D
- Six-cylinder horizontally opposed
- Fuel injected
- 300 hp
Although the radial-powered version retained a traditional agricultural appearance, most operators preferred the smoother, lighter and more economical Lycoming-powered Eagle 300.
Aerodynamics
Several design innovations distinguished the DW-1 from competing agricultural aircraft:
- long-span tapered wings
- high aspect ratio
- integrated spray booms
- spoiler-assisted roll control
- clean fuselage lines
- enclosed cockpit
These features were intended to improve efficiency, reduce fuel consumption and provide excellent low-speed control during spraying operations.
Production
Manufacturer:
Eagle Aircraft Company
Design location:
Boise, Idaho, USA
Production contractor:
Bellanca Aircraft Corporation
Assembly location:
Alexandria, Minnesota
Production period:
- 1979–1983
Production totals remain a point of debate. Contemporary references commonly report 95 aircraft, while other historical sources suggest that up to 136 airframes were completed, reflecting differences in how prototypes and subcontract-built aircraft were counted. No further production followed after the type certificate was transferred in 2002.
Specifications (Eagle 300)
| Item | Specification |
|---|---|
| Crew | 1 |
| Length | 8.38 m (27 ft 6 in) |
| Wingspan | 16.76 m (55 ft) |
| Height | 3.33 m (10 ft 11 in) |
| Wing Area | 35.9 m² (386 sq ft) |
| Empty Weight | 1,202 kg (2,650 lb) |
| Maximum Loaded Weight | 2,449 kg (5,400 lb) |
| Hopper Capacity | 946 L (250 US gal) |
| Engine | Lycoming IO-540-M1B5D |
| Power | 300 hp (225 kW) |
| Landing Gear | Fixed conventional (tailwheel) |
Performance
Published performance data for the DW-1 is relatively limited because the aircraft was certificated as a specialist agricultural aircraft rather than a general aviation touring aircraft. Typical figures for the Lycoming-powered Eagle 300 include:
| Performance | Value |
|---|---|
| Maximum Working Speed | 185 km/h (115 mph) |
| Minimum Working Speed | 105 km/h (65 mph) |
| Typical Spray Speed | 105–145 km/h (65–90 mph) |
| Ferry Speed | Approximately 185–200 km/h (115–125 mph), depending on load and engine |
| Operating Role | Low-level agricultural application |
Unlike touring aircraft, the DW-1 was optimised for precise low-level operations rather than maximum cruise speed or long-range performance.
Operational Characteristics
Agricultural pilots valued the DW-1 for its:
- excellent lift at low speeds
- predictable handling
- good visibility from the enclosed cockpit
- smooth Lycoming engine operation
- efficient spray distribution
- ability to operate from short, rough farm strips
The high-aspect-ratio wings also reduced induced drag, allowing efficient operation with heavy chemical loads.
Legacy
Although produced in relatively small numbers, the Eagle DW-1 was an innovative agricultural aircraft that challenged conventional design thinking. Dean Wilson’s use of sailplane-inspired high-aspect-ratio wings, spoiler-assisted roll control, and integrated spray booms demonstrated that significant aerodynamic gains could be achieved in a crop-spraying aircraft. While the type never matched the commercial success of the Air Tractor or Thrush families, it earned a reputation for efficient low-speed performance and remains a distinctive and respected design within agricultural aviation. Surviving examples continue to operate in agricultural roles in the United States and Australia, illustrating the soundness of its engineering decades after production ceased.