Tundra tire
Encyclopedia
A tundra tire is a large low-pressure tire
used on light aircraft
to allow operations on rough terrain.
Welland Phipps
.
Phipps designed and constructed his own balloon tires in the period after the Second World War and fitted them to a Piper PA-18 Super Cub. Phipps then went on to provide air transportation to much of the Canadian high arctic region. He later established his own airline, Atlas Aviation, which operated a fleet of De Havilland Canada DHC-6 Twin Otter
s on balloon tires. Using the tires, Atlas's DHC-6s established airline service to such remote communities as Resolute, Nunavut
and Grise Fiord, Nunavut
.
and particularly in Alaska
, tundra tires of various designs were often installed under local field approvals by Federal Aviation Administration
inspectors. These approvals were usually granted on the basis of visual inspections and did not include flight testing. After a number of accidents with tundra tire equipped aircraft, culminating with a large number in the fall of 1994, the National Transportation Safety Board
identified that the tundra tires were connected with the accidents. Starting in April 1995 the FAA carried out flight test experiments to determine whether the tundra tires were a contributing factor.
The tests used a Piper PA-18-150 Super Cub equipped in sequence with five different sets of tires, including standard factory tires and tundra tires up to 35 in (89 cm) diameter. The PA-18 was operated at different weights and center of gravity positions.
The testing on the ground revealed that the larger the tire the more restricted the forward visibility on the ground, that there was a nose-down pitching moment when the tires contacted the ground on landing, particularly on a wheel landing, and that tundra tire-equipped aircraft have substantially poorer ground handling characteristics on pavement. In the air the use of tundra tires reduced top speed, rate of climb, angle of climb, range, useful load and stall warning buffet margins.
The tests did not indicate that tundra tires raise stall speed, but did find that, due to increased drag in turns, the aircraft nose tends to drop excessively with an increase in bank angle. If the pilot counteracts this tendency with rudder and stalls the aircraft, the airplane will rapidly enter a spin.
Alaska bush pilots disputed the experimental findings, but, as a result of these experiments the FAA required that all installed tires be subject to a Technical Standard Order
or Parts Manufacturer Approval, have been flight tested and subject to a weight and balance report, determining an acceptable flight envelope. The FAA also limited tundra tires to 35 in (89 cm) in diameter.
Charles McDowell, an Aviat Husky
pilot stated:
Tire
A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...
used on light aircraft
Light aircraft
A light aircraft is an aircraft that has a maximum gross take-off weight of or less.Many aircraft used commercially for freight, sightseeing, photography and scheduled flights are light aircraft.Examples of light aircraft include:...
to allow operations on rough terrain.
History
The tundra style tire has been independently invented at different times and places. In North America its invention is credited to CanadianCanada
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...
Welland Phipps
Welland Phipps
Welland Wilford "Weldy" "Angayuroluk" Phipps was a military pilot and prisoner of war during World War II, a pioneer bush pilot, inventor and a territorial level politician.-World War II:...
.
Phipps designed and constructed his own balloon tires in the period after the Second World War and fitted them to a Piper PA-18 Super Cub. Phipps then went on to provide air transportation to much of the Canadian high arctic region. He later established his own airline, Atlas Aviation, which operated a fleet of De Havilland Canada DHC-6 Twin Otter
De Havilland Canada DHC-6 Twin Otter
The DHC-6 Twin Otter is a Canadian 19-passenger STOL utility aircraft developed by de Havilland Canada and currently produced by Viking Air. The aircraft's fixed tricycle undercarriage, STOL abilities and high rate of climb have made it a successful cargo, regional passenger airliner and MEDEVAC...
s on balloon tires. Using the tires, Atlas's DHC-6s established airline service to such remote communities as Resolute, Nunavut
Resolute, Nunavut
Resolute or Resolute Bay is a small Inuit hamlet on Cornwallis Island in Nunavut, Canada. It is situated at the northern end of Resolute Bay and the Northwest Passage and is part of the Qikiqtaaluk Region....
and Grise Fiord, Nunavut
Grise Fiord, Nunavut
Grise Fiord, is a small Inuit hamlet in the Qikiqtaaluk Region in the territory of Nunavut, Canada. Despite its low population , it is the largest community on Ellesmere Island...
.
Airworthiness issues
In the United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and particularly in Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, tundra tires of various designs were often installed under local field approvals by Federal Aviation Administration
Federal Aviation Administration
The Federal Aviation Administration is the national aviation authority of the United States. An agency of the United States Department of Transportation, it has authority to regulate and oversee all aspects of civil aviation in the U.S...
inspectors. These approvals were usually granted on the basis of visual inspections and did not include flight testing. After a number of accidents with tundra tire equipped aircraft, culminating with a large number in the fall of 1994, the National Transportation Safety Board
National Transportation Safety Board
The National Transportation Safety Board is an independent U.S. government investigative agency responsible for civil transportation accident investigation. In this role, the NTSB investigates and reports on aviation accidents and incidents, certain types of highway crashes, ship and marine...
identified that the tundra tires were connected with the accidents. Starting in April 1995 the FAA carried out flight test experiments to determine whether the tundra tires were a contributing factor.
The tests used a Piper PA-18-150 Super Cub equipped in sequence with five different sets of tires, including standard factory tires and tundra tires up to 35 in (89 cm) diameter. The PA-18 was operated at different weights and center of gravity positions.
The testing on the ground revealed that the larger the tire the more restricted the forward visibility on the ground, that there was a nose-down pitching moment when the tires contacted the ground on landing, particularly on a wheel landing, and that tundra tire-equipped aircraft have substantially poorer ground handling characteristics on pavement. In the air the use of tundra tires reduced top speed, rate of climb, angle of climb, range, useful load and stall warning buffet margins.
The tests did not indicate that tundra tires raise stall speed, but did find that, due to increased drag in turns, the aircraft nose tends to drop excessively with an increase in bank angle. If the pilot counteracts this tendency with rudder and stalls the aircraft, the airplane will rapidly enter a spin.
Alaska bush pilots disputed the experimental findings, but, as a result of these experiments the FAA required that all installed tires be subject to a Technical Standard Order
Technical Standard Order
A Technical Standard Order is a minimum performance standard issued by the United States Federal Aviation Administration for specified materials, parts, processes, and appliances used on civil aircraft. Articles with TSO design approval are eligible for use on the United States type certificated...
or Parts Manufacturer Approval, have been flight tested and subject to a weight and balance report, determining an acceptable flight envelope. The FAA also limited tundra tires to 35 in (89 cm) in diameter.
Operators
Until the end of the 20th century tundra tires were mostly used by bush operators flying in remote areas. In the early part of the 21st century many sales of tundra tires have been to recreational pilots. Bill Duncan, president of Alaskan Bushwheels a tundra tire manufacturer explains:Charles McDowell, an Aviat Husky
Aviat Husky
|-See also:...
pilot stated: