Birdman Chinook. The Birdman Chinook is a family of single and two-place, pusher configuration, high-wing ultralight aircraft that was first flown on 12 December 1982 and produced by Birdman Enterprises of Edmonton, Alberta, Canada, starting in 1983.

The Chinook design has evolved through several models over time, and has been produced by two companies. Over 850 in total have been completed and flown, and kits remain in production in the 21st century.

Design and development

Chinook WT-11

Design goals
The first Chinook model introduced was the single-seat WT-11, which entered the market in 1983. The WT-11 was the eleventh aircraft designed by Ukrainian-born aeronautical engineer Vladimir Talanczuk, a graduate of the Polish Institute for Aviation Specialists. The airfoil was developed by Dr Dave Marsden at the University of Alberta and is designated as the UA 80/1.

The company design goals for the WT-11 were:

Good flying characteristics
Simplicity of construction
Maximization of aesthetics

Designer Talanczuk stated his own design intentions:

The WT-11 was designed to comply with the then-new US FAR 103 Ultralight Vehicles category, including the maximum  empty weight. With the  Rotax 277 single cylinder, two stroke powerplant the aircraft has a factory standard empty weight of . The  Rotax 377 engine became quickly available as an option to give the aircraft more power on floats.

In 1987, the WT-11 was redesignated as the Chinook 1S (1 Seat) by the company to align its nomenclature with the later two-seat Chinook 2S model.

Construction
Talanczuk's design is a high-wing, enclosed cabin monoplane with a high aspect ratio wing of 8.75:1, giving a large wingspan of . This gives the WT-11 a very low span-loading as well as a light wing loading. The glide ratio is 10:1 at  and minimum sink is 350 fpm (1.78 m/s) at . Chinooks have been soared power-off for long duration flights. The low-drag airframe and high aspect ratio wings gave remarkably good performance on the  Rotax 277 engine and the aircraft can cruise at  burning 1.5 US gallons per hour (5.7 litres/h) of automotive fuel, giving a range of  on  of fuel.

The aircraft is constructed entirely from 6061-T6 aluminium tubing, bolted together with aircraft-grade AN hardware and covered with 3.9 oz/yd2 (132 g/m2) Dacron. The covering includes zippers to facilitate inspection. The structure was static load tested to +6/-3 g. The fuselage is built on a  central "spinal" tube that supports the cockpit and the tail surfaces. The cockpit is of a unique pentagonal cross-section that provides a very wide  cabin at hip level. The upper cockpit tubing curves down to the aircraft's nose at a ratio of 3:1 to provide a compromise between internal cockpit space and streamlining and gives the Chinook its distinctive profile.

The landing gear is of conventional configuration, with bungee suspension, giving good rough field capabilities. The enclosed cabin includes a cargo area that is located on the aircraft's center of gravity, eliminating trim changes as the load varies.

The wing is a two-spar design, supported by a "V" strut and jury struts. The wing has internal lift and drag bracing wires. The ailerons were originally designed to be "gapless", with the wing's Dacron covering extending over the ailerons. This is sometimes referred to as wing warping, but it differs from that employed on pioneer aircraft. In 1986, the company abandoned the "gapless" aileron design and moved to a more conventional separate aileron. Conversion kits for the existing aircraft fleet were made available.  The WT-11's wings are removable by two people in 15 minutes. The tail surfaces use a similar sealed-gap system, utilizing seamless transitions from the fixed fin and horizontal stabilizer to the movable rudder and elevator.

The factory claimed that construction time from the assembly kit was 100 hours for a first time builder. The price for a WT-11 in 1984 was Can$7995 (US$6395).

Test flying
Test flying the WT-11 was carried out following the first flight on 12 December 1982 at Wizard Lake, Alberta, by company chief test pilot Dennis Maland.

Initial results showed that with the  Rotax 277 engine the aircraft would sustain level flight at low throttle settings and would cruise comfortably at . The stall speed was noted as 23-25 mph (37–41 km/h). Maland rated the rudder and elevators as "very responsive" and the ailerons as "less sensitive but good", with roll rates from 45 to 45 degrees of 3.5 seconds at cruise speed.

Cross wind testing showed the aircraft was controllable in winds of  at 45 degrees and  at 90 degrees. The aircraft was flown in  surface winds safely. Take-off roll was recorded as 100–200 feet (31–62 m) and distance to clear a  obstacle was 200–300 feet (62–93 m) at  above sea level.

Extensive stall  and spin testing was carried out at Wizard Lake on 28 December 1982. Straight-ahead and turning power-off stalls resulted in a stable mush condition. Power-on stalls from 30 degrees nose up resulted in a +15 degree nose up stable mush, with no wing drop tendency. A near-vertical pitch resulted in a clean stall, with a smooth pitch forward and recovery to level flight with no wing drop tendency.

Spin testing entered from level flight, snap rolls and turning stalls failed to produce a spin condition as the WT-11 just mushed to level flight. These tests resulted in the company billing the aircraft as "Won't Spin".

The remaining flight testing established the service ceiling as  and the absolute ceiling as . Many dives to the VNE of  were completed without deformation, flutter or instability. Outside loops,  rolls, snap rolls, stall turns, tail slides and inverted flight were all completed as test procedures, although the company recommended against customers from conducting these manoeuvres.

Floats
The WT-11 was tested on fiberglass floats, mounted close to the fuselage. Company testing showed take-off distances of about  on the water and no need for additional vertical surfaces to be added.

Chinook 2S
Building on the success of the single-seat Chinook, Birdman introduced the two place Chinook 2S (2 seater) in 1984, and it quickly gained popularity as an ultralight trainer and also as a recreational aircraft. The 2S combined the WT-11's ease of handling, docile stall characteristics and spin-proofness with the reliable Rotax 447  and later the  Rotax 503  engine. One flight review writer noted, "The stall was the most benign that I have even seen in any airplane. At full back stick, it just mushes downward slowly with the nose level, at about 200-400 rpm. Releasing the stick returns the Chinook to flying with little altitude loss."

The construction of the 2S is similar to the WT-11, with the wingspan increased by  and the same fuselage as the WT-11, with the second seat where the WT-11's baggage area is located. The fuel tank was relocated from the fuselage to both wing struts as aerodynamically-shaped plastic tanks, where they are visible in flight and the fuel level can be quickly determined. Some WT-11s have had these strut tanks installed as well.

In assessing the handling of the 2S, one reviewer wrote:

The two models of the Chinook built by Birdman were only in production for five years before the company went out of business in late 1987, but close to 700 aircraft were delivered in that time. The kits were made at the Canadian Ultralight Manufacturing facility in St Paul, Alberta.

Chinook Plus 2

One of the owners of a Chinook 2S at the time Birdman Enterprises went out of business was Brent Holomis. Seeing the opportunity to step in and provide parts for the fleet he founded Aircraft Sales and Parts (ASAP) in 1988, in Vernon, British Columbia. Initially ASAP concentrated on supplying parts, but with assistance from the University of Alberta, Holomis redesigned the aircraft. The new model, a two-seater introduced in 1989 was designated the Chinook Plus 2 and incorporated an all new wing of reduced span ( versus the 2S's ) and lower aspect ratio with a greater number of ribs and covered with Ceconite in place of untreated Dacron. The wing features flaperons. The new model has a completely new landing gear and many other improvements over the 2S and was built by Canadian Ultralight Manufacturing, which ASAP acquired. The Plus 2 retains the strut-mounted fuel tanks introduced on the 2S.

The Chinook Plus 2 is available in kit form with a large number of engine options, including the  Rotax 503, the four-stroke  HKS 700E, the  Rotax 582 and the  Rotax 912. The heavier engines, particularly the Rotax 912, have been noted as changing the aircraft's handling characteristics and making the aircraft less stable in pitch and yaw.

With the four-stroke HKS 700E engine, the Plus 2 has a top speed af  and a high cruise of , with a  economy cruise, burning only about  per hour, giving a five-hour endurance with standard tanks. Solo power off stalls are  and are "mild and uneventful". The aircraft has a very low power off sink rate of about 350 fpm (1.78 m/s).

The Plus 2 initially had a gross weight of , but this was progressively increased to its present .

Reviewer Dan Johnson, writing in EAA Sport Pilot & Light Sport Aircraft Magazine in January 2008, described the Chinook Plus 2 with the HKS 700E engine:

The factory claimed that a first time builder can complete the Chinook Plus 2 in 220 hours of labour.

Under Aeroplane Manufactory Management 
The rights to the Chinook Plus 2 were sold to a US company, the Aeroplane Manufactory in 2013, which put the design back into production in 2016. Aeroplane Manufactory ("AM") is the trade name for the Early Aeroplane Manufactory LLC, a Texas limited liability company founded in 2003 and was based at Gloster Aerodrome (1XA7), near Houston, Texas. AM was owned and operated by John A. Couch and Kim S. Evans-Couch who also own and operate Gloster Aerodrome, LP. In the fall of 2013, AM purchased all of the assets of Aircraft Sales and Parts Ltd. based in Vernon, British Columbia and its affiliate, Canadian Ultralight Manufacturing Ltd. based in St. Paul, Alberta, together ("ASAP"). ASAP produced the Beaver and Chinook lines of light aircraft kits in Canada for over 25 years until its owners decided to retire from the business and liquidate the companies. 

In November 2013, AM received consolidated shipments of parts, materials, equipment, tooling, jigs, inventory, machines, intellectual property, and records from two locations in Canada. These shipments comprised five eighteen-wheeler truckloads of assets. AM repurposed a large hangar at Gloster Aerodrome to accommodate the received assets from ASAP. The repurposing process took several months to complete.

The unpacking, counting, and computerization of existing inventory extended over additional months, with the installation and operationalization of machinery taking even longer. In early November 2014, upon completion of the facility and machinery setup, Glenn and Kurt Holomis from St. Paul visited Gloster Aerodrome to train the Couches on fabrication and assembly techniques.

As with many small businesses facing learning curves, the Couches worked to provide quality products at competitive prices, building upon the Holomis' established reputation. The company subsequently produced Chinook Plus 2 parts and developed full kits for the Chinook DR and Chinook SJ models.

Dan Reynolds 
Dan Reynolds is a Canadian bush pilot and aircraft modifier known for his achievements in Short Take-Off and Landing (STOL) competitions and his extensive experience flying ultralight aircraft in extreme conditions. Based in Dawson City, Yukon Territory, Reynolds has been flying in bush environments since 1978.

Career and Achievements 
Reynolds gained prominence in the aviation community when he set a record at the 2018 Valdez STOL competition with a landing distance of 9.5 feet, and second place that included the shortest landing at the 2020 Lonestar STOL competition in Gainesville, Texas. He primarily flies modified Chinook aircraft, which he has extensively customized for improved performance in bush flying conditions.

As a commercial pilot, Reynolds holds an air charter license and operates several aircraft, including two Super Cubs and a Cessna 185. However, he is best known for his work with ultralight and experimental light sport aircraft.

Aircraft Modifications 
Reynolds is recognized for his modifications to the Chinook aircraft, particularly in improving its useful load capacity. His modified Chinook can carry a payload of approximately 600 pounds, despite having an empty weight of only about 520 pounds.

Engine Expertise 
Reynolds has extensive experience with Rotax two-stroke engines, including the 503, 582, 618, and 670 models. He has achieved remarkable longevity with these engines, running some Rotax 503 engines for over 800 hours before overhaul, far exceeding the manufacturer's recommendation of 300 hours.

Other Activities 
In addition to his aviation pursuits, Reynolds is involved in hay production for his local community and operates an outfitting business from August to October each year.

Reynolds continues to participate in STOL competitions and is known in the bush flying community for his skills in winter flying conditions, often operating his aircraft on skis.

Chinook DR 
The Chinook DR was a variant of the Chinook Plus 2, featuring a Dan Reynolds designed (DR) Landing Gear System. It was equipped with standard 5-gallon strut tanks and a metalized fuselage. The aircraft could be modified to include optional in-wing 10-gallon aluminum tanks.

The Chinook DR aircraft kit was offered in two versions: one compatible with the 2-stroke Rotax 582UL engine, and another designed for the 4-stroke Rotax 912UL engine. The kit provided components necessary for aircraft assembly, excluding the engine, engine accessories, propeller, and paint.

This aircraft was noted for its short takeoff and landing (STOL) capabilities.

Chinook SJ 
The Chinook SJ was a significantly modified version of the Chinook DR. It featured an extended body tube and an enlarged rear fuselage, which allowed for a larger door and increased passenger or flight instructor space. The front cabin was taller than previous Chinook models and included lighter, larger aluminum seats.

Modifications to the Chinook SJ included:

 Increased surface area for flaperons, elevator, and rudder
 Strengthened wings, jury struts, and lift struts to increase useful load
 A larger tailwheel compared to other Chinook models
 Two 10-gallon internal aluminum wing tanks as standard, with the option to install both strut and in-wing tanks per customer request
 Optional dihedral for improved stability in low-speed flight regimes

The Chinook SJ aircraft kit was available in two versions: one compatible with the 2-stroke Rotax 582UL engine, and another designed for the 4-stroke Rotax 912UL engine. The kit provided components necessary for aircraft assembly, excluding the engine, engine accessories, propeller, and paint. 

This model was designed to withstand the demands of flight training and extreme bush flying conditions.

Under Legacy AIR1 Management 
In August of 2023, the Aeroplane Manufactory, including all inventory and product rights, was sold to fellow Texas-based company Legacy AIR1 (Formerly Legacy Light Sport Group (LSG)). They are modernizing and upgrading the aircraft kit with factory and custom-designed parts at their facility in Plainview, TX at the Hale County Airport. The most recent update from the company states: "Since taking over the company, we have made significant progress in setting up our new manufacturing facility in Plainview, Texas. All of the necessary equipment, tools, and existing inventory have been moved to our two hangars, and we have nearly completed the process of organizing, inventorying, and labeling everything." 

"While we have been making great strides, we also understand that producing a high-quality aircraft kit takes time. When the Couch family purchased the rights to the Chinook in 2013, it took them nearly three years to deliver their first aircraft. We are pleased to report that we are ahead of that schedule, but we also want to ensure that we deliver a product that meets our high standards and exceeds your expectations."

Operational history
The Chinook WT-11 design won Reserve Grand Champion at AirVenture in 1983 and again in 1984.

In August 1983, test pilot Dennis Maland flew a WT-11 with the standard Rotax 277 engine to a height of .

In November 1984, Jack Hughes flew a WT-11 across the width of Australia from Orange, New South Wales, to Perth, Western Australia, in 14 days and 49 flying hours, a distance of .

In 1993, a  Rotax 582-powered Chinook Plus 2 on skis and Full Lotus Floats was used by the National Geographic Society in filming a television special about marine mammals in the Canadian Arctic.

In 2018, Dan Reynolds, designer of the "DR" gear option for the Chinook DR line of aircraft broke the world record for shortest landing in the LSA class at the Valdez, Alaska STOL Competition. In 2020, the Yukon bush pilot came in second place, and with the shortest landing at the 2020 Lone Star STOL competition in Gainesville, Texas.

Variants
Chinook WT-11-277
Single seat, powered by a  Rotax 277, produced by Birdman Enterprises 1983-1986.
Chinook WT-11-377
Single seat, powered by a  Rotax 377, produced by Birdman Enterprises 1984-1986.
Chinook 1S
Later designation for the WT-11, to align is nomenclature with the 2S. Single seat, powered by a  Rotax 277 or optionally a  Rotax 377, produced by Birdman Enterprises 1987.
Chinook 2S
Two seat, powered by a  Rotax 447 or  Rotax 503, produced by Birdman Enterprises 1984-1987.
Chinook Plus 2
Two seat, powered by a  Rotax 503,  HKS 700E,  Rotax 582 or  Rotax 912, produced by ASAP 1989-2013 and the parts were continued in production by Aeroplane Manufactory from 2016-2023. 
Chinook DR

Factory-modified Chinook Plus 2 with the DR Landing Gear System, produced by Aeroplane Manufactory from 2016-2023. Production will resume in 2024 or 2025 under Legacy AIR1

Chinook SJ

Two seat, powered by a 2 stroke (Rotax 582UL) or 4 stroke (Rotax 912UL) Production will resume in 2024 under Legacy AIR1

Specifications (Chinook WT-11)

See also

References

External links

1980s Canadian ultralight aircraft
Homebuilt aircraft
Single-engined pusher aircraft
Aircraft first flown in 1982
High-wing aircraft
Aircraft with fixed conventional landing gear