Tundra tires
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Tundra tires
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.
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When Budd Davisson taught me to land the Pitts - he took air out of the 500x5.00 tyres. Book says 35psi - Budd has down at 20 as it helped damp the landing but the increased footprint was insignificant.
I flew a Pitts with tyres PUMPED to 80 psi at Reno (the thinking was smaller footprint smaller resistance drag). It was really uncomfortable to land as there was no give in the tyre walls. A bit like riding a solid wheel bike over cobbles at 90mph!
Those Tundra tyres look like they could be a handful - definetely a dab on the brakes after take off to stop them spinning and ensuing precession.
Stik
I flew a Pitts with tyres PUMPED to 80 psi at Reno (the thinking was smaller footprint smaller resistance drag). It was really uncomfortable to land as there was no give in the tyre walls. A bit like riding a solid wheel bike over cobbles at 90mph!
Those Tundra tyres look like they could be a handful - definetely a dab on the brakes after take off to stop them spinning and ensuing precession.
Stik
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Would it be correct to assume that if the aircraft was hypothetically certified with Tundra tyres the demonstrated crosswind limits would be less due to the issue of increased friction and drag during spin up when landing wing low and opposite rudder?
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definetely a dab on the brakes after take off to stop them spinning and ensuing precession
hypothetically certified with Tundra tyres the demonstrated crosswind limits
Are these differences less noticeable on a tricycle?
The closest I have seen was this C 206 in Tuk, Alaska. Note the "mud" flaps on the main wheels to prevent gravel damage of the H stab.