Pilot DAR
4th Aug 2012, 14:30
A question was asked about tundra tires on another thread, and its perhaps better addressed in its own thread, as others will have valuable input too.
When installed on a small taildragger, tundra tires can make paved runway landings more challenging. Two reasons for this: Superior traction and increased spin up forces.
By its nature, the tundra tire has a larger footprint. Reduced tire pressure can be one reason, depending upon how it is set, and a larger diameter, so more contact along the direction of rolling. With more traction any tendancy to groundloop is worsened, and recovery more difficult.
The heavier, and larger diameter tire will create more drag as it spins up upon contact with the ground. The aircraft tends to lurch. If you have touched down one wheel low, that wheel will be subjected to spin up forces first, and the aircraft will want to yaw. If that wheel also has a good grip on the runway, its more traction for a groundloop.
Bear in mind that the controllability of the aircraft, and ease with which the pilot can maintain directional control was demonstrated with the "standard" tires. That does not mean that tundra tires aren't fine, but they may not have been proven during certification testing.
Operations on grass allow the tires to slide a bit, rather than gripping right in, so the forces which might aggravate a groundloop are reduced. And the spin up will occur over a longer period, so the tuck is less forceful.
I learned these things when the C 150 taildragger I used to fly, was put on tundra tires "just for fun". It became a whole different aircraft on the runway.
When installed on a small taildragger, tundra tires can make paved runway landings more challenging. Two reasons for this: Superior traction and increased spin up forces.
By its nature, the tundra tire has a larger footprint. Reduced tire pressure can be one reason, depending upon how it is set, and a larger diameter, so more contact along the direction of rolling. With more traction any tendancy to groundloop is worsened, and recovery more difficult.
The heavier, and larger diameter tire will create more drag as it spins up upon contact with the ground. The aircraft tends to lurch. If you have touched down one wheel low, that wheel will be subjected to spin up forces first, and the aircraft will want to yaw. If that wheel also has a good grip on the runway, its more traction for a groundloop.
Bear in mind that the controllability of the aircraft, and ease with which the pilot can maintain directional control was demonstrated with the "standard" tires. That does not mean that tundra tires aren't fine, but they may not have been proven during certification testing.
Operations on grass allow the tires to slide a bit, rather than gripping right in, so the forces which might aggravate a groundloop are reduced. And the spin up will occur over a longer period, so the tuck is less forceful.
I learned these things when the C 150 taildragger I used to fly, was put on tundra tires "just for fun". It became a whole different aircraft on the runway.