Private Flying LAA/BMAA/BGA/BPA The sheer pleasure of flight.

Tundra tires

Old 4th Aug 2012, 14:30
  #1 (permalink)  
Moderator
Thread Starter
 
Join Date: Aug 2006
Location: Ontario, Canada
Age: 60
Posts: 4,870
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.
Pilot DAR is offline  
Old 4th Aug 2012, 17:09
  #2 (permalink)  
 
Join Date: Jul 2010
Location: EBZH
Posts: 2,624
Thank you!
Jan Olieslagers is offline  
Old 4th Aug 2012, 18:52
  #3 (permalink)  
 
Join Date: Aug 2000
Location: Norfolk
Posts: 1,966
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
stiknruda is offline  
Old 4th Aug 2012, 18:53
  #4 (permalink)  
 
Join Date: Aug 2005
Location: Glens o' Angus by way of LA
Age: 58
Posts: 1,974
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?
piperboy84 is offline  
Old 4th Aug 2012, 19:48
  #5 (permalink)  
 
Join Date: Aug 2010
Location: Ecuador
Age: 43
Posts: 222
Are these differences less noticeable on a tricycle?

###Ultra Long Hauler###
Ultra long hauler is offline  
Old 4th Aug 2012, 21:20
  #6 (permalink)  
Moderator
Thread Starter
 
Join Date: Aug 2006
Location: Ontario, Canada
Age: 60
Posts: 4,870
definetely a dab on the brakes after take off to stop them spinning and ensuing precession
This is something I recommend against. That spinning tire has increased it's diameter a little due to centrifugal forces, and is not being pressed into the rim by the aircraft weight. Too rapid application of the brakes can stop the rim, but the tire not so fast, and shearing off the valve stem is a possibility. Let them slow down on their own.

hypothetically certified with Tundra tyres the demonstrated crosswind limits
I don't know a lot about the thresholds of directional control certification. I've only done certification test flying on three taildraggers. The Beaver and C 185 were very forgiving, and met the requirement, so I was not asked to demonstrate more. I did not get into "challenging" territory with them. The Siai Marchetti was a different beast entirely, but was not being "certified" so I could pick my points. I did not pick crosswinds!

Are these differences less noticeable on a tricycle?
I would expect so, but I have never flown a tundra tire tricycle. There are much less common, as they are just not a great idea. If the ground is so rough/soft to require tundra tires, you're probably going to rip the nosewheel right off! It's also hard to find a nosewheel fork big enough to reach around.

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.

Pilot DAR is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.