Birdman Chinook
Encyclopedia
The Birdman Chinook is a family of single and two-place, pusher configuration
Pusher configuration
In a craft with a pusher configuration the propeller are mounted behind their respective engine. According to Bill Gunston, a "pusher propeller" is one mounted behind engine so that drive shaft is in compression...
, high-wing ultralight aircraft that was first flown on 12 December 1982 and produced by Birdman Enterprises
Birdman Enterprises
This article is about the Canadian ultralight manufacturer. For the unrelated US ultralight manufacturer, see Birdman AircraftBirdman Enterprises Limited was a Canadian aircraft manufacturer that commenced business in 1973 and became well known for its line of hang gliders and later its ultralight...
of Edmonton, Alberta, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
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 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 UkrainianUkraine
Ukraine is a country in Eastern Europe. It has an area of 603,628 km², making it the second largest contiguous country on the European continent, after Russia...
-born aeronautical engineer Vladimir Talanczuk, a graduate of the Polish
Poland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
Institute for Aviation Specialists. The airfoil was developed by Dr Dave Marsden at the University of Alberta
University of Alberta
The University of Alberta is a public research university located in Edmonton, Alberta, Canada. Founded in 1908 by Alexander Cameron Rutherford, the first premier of Alberta and Henry Marshall Tory, its first president, it is widely recognized as one of the best universities in Canada...
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
Ultralight aircraft (United States)
Ultralight aircraft in the United States are much smaller and lighter than ultralight aircraft in all other countries.In the USA ultralights are classified as vehicles and not aircraft and are thus not required to be registered or for the pilot to have a pilot licence or certificate.- US definition...
category, including the maximum 254 lb (115 kg) empty weight. With the 28 hp Rotax 277
Rotax 277
|-Specifications :-See also:...
single cylinder, two stroke powerplant the aircraft has a factory standard empty weight of 250 lb (113 kg). The 35 hp Rotax 377
Rotax 377
|-See also:...
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 35 feet (10.7 m). This gives the WT-11 a very low span-loading as well as a light wing loadingWing loading
In aerodynamics, wing loading is the loaded weight of the aircraft divided by the area of the wing. The faster an aircraft flies, the more lift is produced by each unit area of wing, so a smaller wing can carry the same weight in level flight, operating at a higher wing loading. Correspondingly,...
. The glide ratio is 10:1 at 35 mph (56 km/h) and minimum sink is 350 fpm (1.78 m/s) at 32 mph (51 km/h). Chinooks have been soared
Lift (soaring)
Gliding flight is heavier-than-air flight without the use of thrust. It is employed by gliding animals and by aircraft such as gliders. The most common human application of gliding flight is in sport and recreation using aircraft designed for this purpose...
power-off for long duration flights. The low-drag airframe and high aspect ratio wings gave remarkably good performance on the 28 hp Rotax 277 engine and the aircraft can cruise at 50 mph (80 km/h) burning 1.5 US gallons per hour (5.7 litres/h) of automotive fuel, giving a range of 200 miles (321.9 km) on 5 US gal (19 l) 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
Polyethylene terephthalate
Polyethylene terephthalate , commonly abbreviated PET, PETE, or the obsolete PETP or PET-P, is a thermoplastic polymer resin of the polyester family and is used in synthetic fibers; beverage, food and other liquid containers; thermoforming applications; and engineering resins often in combination...
. The covering includes zippers to facilitate inspection. The structure was static load tested to +6/-3 g
G-force
The g-force associated with an object is its acceleration relative to free-fall. This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and...
. The fuselage
Fuselage
The fuselage is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull...
is built on a 4 in (10 cm) 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 38 in (97 cm) 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
Conventional landing gear
thumb|The [[Piper PA-18|Piper Super Cub]] is a popular taildragger aircraft.thumb|right|A [[Cessna 150]] converted to taildragger configuration by installation of an after-market modification kit....
configuration, with bungee
Bungee cord
A bungee cord , also known as a shock cord, is an elastic cord composed of one or more elastic strands forming a core, usually covered in a woven cotton or polypropylene sheath...
suspension, giving good rough field capabilities. The enclosed cabin includes a cargo area that is located on the aircraft's center of gravity
Center of mass
In physics, the center of mass or barycenter of a system is the average location of all of its mass. In the case of a rigid body, the position of the center of mass is fixed in relation to the body...
, eliminating trim changes as the load varies.
The wing is a two-spar design, supported by a "V" strut
Strut
A strut is a structural component designed to resist longitudinal compression. Struts provide outwards-facing support in their lengthwise direction, which can be used to keep two other components separate, performing the opposite function of a tie...
and jury strut
Jury strut
The jury struts on a monoplane are small subsidiary struts that join the main wing struts to the wing.Jury struts are installed to eliminate unwanted resonance and vibration from the main wing struts and also to prevent main strut compression buckling under negative 'g' loads in the case of...
s. The wing has internal lift and drag bracing wires. The aileron
Aileron
Ailerons are hinged flight control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. The ailerons are used to control the aircraft in roll, which results in a change in heading due to the tilting of the lift vector...
s were originally designed to be "gapless", with the wing's Dacron covering extending over the ailerons. This is sometimes referred to as wing warping
Wing warping
Wing warping was an early system for lateral control of a fixed-wing aircraft. The technique, used and patented by the Wright brothers, consisted of a system of pulleys and cables to twist the trailing edges of the wings in opposite directions...
, 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
Rudder
A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft or other conveyance that moves through a medium . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane...
and elevator
Elevator (aircraft)
Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's orientation by changing the pitch of the aircraft, and so also the angle of attack of the wing. In simplified terms, they make the aircraft nose-up or nose-down...
.
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$
Canadian dollar
The Canadian dollar is the currency of Canada. As of 2007, the Canadian dollar is the 7th most traded currency in the world. It is abbreviated with the dollar sign $, or C$ to distinguish it from other dollar-denominated currencies...
7995 (US$
United States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....
6395).
Test flying
Test flyingFlight test
Flight test is a branch of aeronautical engineering that develops and gathers data during flight of an aircraft and then analyzes the data to evaluate the flight characteristics of the aircraft and validate its design, including safety aspects...
the WT-11 was carried out following the first flight on 12 December 1982 at Wizard Lake
Wizard Lake
Wizard Lake is a lake in Alberta located south of Calmar. It is a popular recreation spot due to its proximity to Edmonton.- Amenities :Wizard Lake is home to Jubilee Campground which has 100 stalls in total. The lake has recently been refitted on the east shore for a public swimming location.-...
, Alberta, by company chief test pilot Dennis Maland.
Initial results showed that with the 28 hp Rotax 277 engine the aircraft would sustain level flight at low throttle settings and would cruise comfortably at 50 mph (80 km/h). 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 45-45 degrees of 3.5 seconds at cruise speed.
Cross wind testing showed the aircraft was controllable in winds of 20 mph (32 km/h) at 45 degrees and 15 mph (24 km/h) at 90 degrees. The aircraft was flown in 35 mph (56 km/h) surface winds safely. Take-off roll was recorded as 100–200 feet (31–62 m) and distance to clear a 50 ft (15 m) obstacle was 200–300 feet (62–93 m) at 2500 ft (762 m) above sea level.
Extensive stall
Stall (flight)
In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases. This occurs when the critical angle of attack of the foil is exceeded...
and spin
Spin (flight)
In aviation, a spin is an aggravated stall resulting in autorotation about the spin axis wherein the aircraft follows a corkscrew downward path. Spins can be entered intentionally or unintentionally, from any flight attitude and from practically any airspeed—all that is required is sufficient yaw...
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 15000 ft (4,572 m) and the absolute ceiling as 18400 ft (5,608 m). Many dives to the VNE
V speeds
In aviation, V-speeds are standard terms used to define airspeeds important or useful to the operation of all aircraft including fixed-wing aircraft, gliders, autogiros, helicopters, and dirigibles...
of 85 mph (137 km/h) were completed without deformation, flutter or instability. Outside loops, rolls
Aileron roll
The Aileron Roll is an aerobatic maneuver in which the aircraft does a full 360° revolution about its longitudinal axis. When executed properly, there is no appreciable change in altitude and the aircraft exits the maneuver on the same heading as it entered...
, 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 fiberglassFiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...
floats, mounted close to the fuselage. Company testing showed take-off distances of about 300 feet (91.4 m) 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 spinSpin (flight)
In aviation, a spin is an aggravated stall resulting in autorotation about the spin axis wherein the aircraft follows a corkscrew downward path. Spins can be entered intentionally or unintentionally, from any flight attitude and from practically any airspeed—all that is required is sufficient yaw...
-proofness with the reliable Rotax 447
Rotax 447
|-Specifications :...
42 hp and later the Rotax 503
Rotax 503
|-Specifications :...
50 hp 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 2 ft (0.6096 m) 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
Aircraft Sales and Parts
Aircraft Sales and Parts is a Canadian kit aircraft and parts manufacturer, based in Vernon, British Columbia.ASAP produces a line of single and two place ultralight kit aircraft, powered parachutes and parts though the parent company and also through its divisions Summit Powered Parachutes, Steel...
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 PartsAircraft Sales and Parts
Aircraft Sales and Parts is a Canadian kit aircraft and parts manufacturer, based in Vernon, British Columbia.ASAP produces a line of single and two place ultralight kit aircraft, powered parachutes and parts though the parent company and also through its divisions Summit Powered Parachutes, Steel...
(ASAP) in 1988, in Vernon, British Columbia
Vernon, British Columbia
Vernon is a city in the south-central region of British Columbia, Canada. Named after Forbes George Vernon, a former MLA of British Columbia who helped found the famed Coldstream Ranch, the City of Vernon was incorporated on December 30, 1892. The City of Vernon has a population of 35,944 , while...
. 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 (32 ft (10 m) versus the 2S's 37 ft (11 m)) and lower aspect ratio with a greater number of ribs and covered with Ceconite in place of untreated Dacron. The wing features flaperon
Flaperon
A flaperon is a type of aircraft control surface that combines aspects of both flaps and ailerons. In addition to controlling the roll or bank of an aircraft as do conventional ailerons, both flaperons can be lowered together to function similarly to a dedicated set of flaps...
s. The new model has a completely new landing gear and many other improvements over the 2S and is 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 50 hp Rotax 503
Rotax 503
|-Specifications :...
, the four-stroke 60 hp HKS 700E
HKS 700E
|-See also:...
, the 64 hp Rotax 582
Rotax 582
|-Specifications :-External links:*...
and the 80 hp 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
Flight dynamics
Flight dynamics is the science of air vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle's center of mass, known as pitch, roll and yaw .Aerospace engineers develop control systems for...
and yaw
Yaw
The word yaw can refer to:* Yaw angle, one of the Tait-Bryan angles, describing the heading of a vehicle or machine, and some other related elements:**Yaw system, component responsible for the orientation of a wind turbine towards the wind....
.
With the four-stroke HKS 700E engine the Plus 2 has a top speed af 90 mph (145 km/h) and a high cruise of 80 mph (129 km/h), with a 65 mph (105 km/h) economy cruise, burning only about 2 US gal (8 l) per hour, giving a five hour endurance with standard tanks. Solo power off stalls are 35 mph (56 km/h) 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 900 lb (408 kg), but this was progressively increased to its present 1050 lb (476 kg).
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 claims that a first time builder can complete the Chinook Plus 2 in 220 hours of labour.
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
Rotax 277
|-Specifications :-See also:...
engine to a height of 18500 ft (5,639 m).
In November 1984 Jack Hughes flew a WT-11 across the width of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
from Orange, New South Wales
Orange, New South Wales
Orange is a city in the Central West region of New South Wales, Australia. It is west of the state capital, Sydney, at an altitude of . Orange has an estimated population of 39,329 and the city is a major provincial centre....
to Perth, Western Australia
Perth, Western Australia
Perth is the capital and largest city of the Australian state of Western Australia and the fourth most populous city in Australia. The Perth metropolitan area has an estimated population of almost 1,700,000....
, in 14 days and 49 flying hours, a distance of 2050 nmi (3,797 km).
In 1993 a 64 hp Rotax 582
Rotax 582
|-Specifications :-External links:*...
-powered Chinook Plus 2 on skis and Full Lotus Floats was used by the National Geographic Society
National Geographic Society
The National Geographic Society , headquartered in Washington, D.C. in the United States, is one of the largest non-profit scientific and educational institutions in the world. Its interests include geography, archaeology and natural science, the promotion of environmental and historical...
in filming a television special about marine mammals in the Canadian Arctic.
Variants
Chinook WT-11-277- Single seat, powered by a 28 hp Rotax 277Rotax 277|-Specifications :-See also:...
, produced by Birdman Enterprises 1983-1986.
Chinook WT-11-377
- Single seat, powered by a 35 hp Rotax 377Rotax 377|-See also:...
, 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 28 hp Rotax 277Rotax 277|-Specifications :-See also:...
or optionally a 35 hp Rotax 377Rotax 377|-See also:...
, produced by Birdman Enterprises 1987.
Chinook 2S
- Two seat, powered by a 42 hp Rotax 447Rotax 447|-Specifications :...
or 50 hp Rotax 503Rotax 503|-Specifications :...
, produced by Birdman Enterprises 1984-1987.
Chinook Plus 2
- Two seat, powered by a 50 hp Rotax 503Rotax 503|-Specifications :...
, 60 hp HKS 700EHKS 700E|-See also:...
, 64 hp Rotax 582Rotax 582|-Specifications :-External links:*...
or 80 hp Rotax 912, produced by ASAP 1989-present.