The Murphy Builders Site

Posted: **Fri Feb 17, 2012 8:27 pm**

I have 800X6 aircraft tires and the bungee gear on rebel 206 and about half
of my landings are in hay fields, lake beds,etc. They work very well. I
tried 850X6s for a while but sure did notice alot more drag. Sure have got
alot of good info. from you guys. Thanks Dave
-----Original Message-----
From: A G Yeoman <yeoman@voyager.co.nz>
To: Murphy Rebel Builders List <murphy-rebel@dcsol.com>
Date: Saturday, October 21, 2000 1:45 PM
Subject: Re: New Rebel with spring gear.

Hi All,
I tend to use the term 'braking loads' as a means to describe
the type of load involved, the actual braking will obviously cause these
types of loads but I think the main contributor is the bumps and hollows

you

find on rough strips.

This being the case the larger tyres are far more of a plus than a minus in
minimising the stresses as the larger diameter and surface area tend to
'smooth' out the road ahead.

Cheers

Alister

----- Original Message -----
From: Ralph Baker <rbaker@sumter.net>
To: <murphy-rebel@dcsol.com>
Sent: Sunday, October 22, 2000 8:45 AM
Subject: New Rebel with spring gear.

There an offsetting factors regarding larger tires that have not been
mentioned.
1- Larger diameter tires increase the lever arm through which the
retarding (braking) force is transmitted to the
ground. Said simply, for equivalent brake pedal pressure there is less
slowing effect with the larger tires. This will result in less torque on
the gear. Of course, with greater pedal pressure there is a "crossover
point" where the greater pedal pressure will increase the gear leg torque
above "standard".
2- Braking effects aside, the larger diameter tires will climb out of
holes and over obstacles more easily than smaller diameter. Ask any dirt
biker about using a 21" front tire versus an 18" tire in the rough.
3- The larger tires are normally run at lower tire pressures and as such
will absorb more jolts and transmit less peak force to the gear and

thence

to the fuselage. Like a recoil pad on a rifle, the energy doesn't

change,

it is just spread out over a longer time.
4- From the "no free lunch" department, the larger tires will cost some
cruise speed.

For what it's worth, we're putting the 8:00x6 main tires and SR tail tire
on our Elite. This will primarily be used in Idaho and Montana
backcountry
and for us the positives predominate. May get a spare rim set and 6:00x6
tires for estimated increase 4-7 mph for the long trips.

Ralph Baker / Sue Scouten
Furiously building Elite 611E in South Carolina so we can move West.

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Archives located at:
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Posted: **Fri Feb 17, 2012 8:27 pm**

There an offsetting factors regarding larger tires that have not been
mentioned.
1- Larger diameter tires increase the lever arm through which the
retarding (braking) force is transmitted to the
ground. Said simply, for equivalent brake pedal pressure there is less
slowing effect with the larger tires. This will result in less torque on
the gear. Of course, with greater pedal pressure there is a "crossover
point" where the greater pedal pressure will increase the gear leg torque
above "standard".
2- Braking effects aside, the larger diameter tires will climb out of
holes and over obstacles more easily than smaller diameter. Ask any dirt
biker about using a 21" front tire versus an 18" tire in the rough.
3- The larger tires are normally run at lower tire pressures and as such
will absorb more jolts and transmit less peak force to the gear and thence
to the fuselage. Like a recoil pad on a rifle, the energy doesn't change,
it is just spread out over a longer time.
4- From the "no free lunch" department, the larger tires will cost some
cruise speed.

For what it's worth, we're putting the 8:00x6 main tires and SR tail tire
on our Elite. This will primarily be used in Idaho and Montana backcountry
and for us the positives predominate. May get a spare rim set and 6:00x6
tires for estimated increase 4-7 mph for the long trips.

Ralph Baker / Sue Scouten
Furiously building Elite 611E in South Carolina so we can move West.
*-----------------------------------------------------------------------------------*
The Murphy Rebel Builders List is for the discussion
between builders and owners of Murphy Rebel aircraft.
Archives located at:
http://www.dcsol.com/murphy-rebel/lists/default.htm
*-----------------------------------------------------------------------------------*

-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

Posted: **Fri Feb 17, 2012 8:27 pm**

Hi All,
I tend to use the term 'braking loads' as a means to describe
the type of load involved, the actual braking will obviously cause these
types of loads but I think the main contributor is the bumps and hollows you
find on rough strips.

This being the case the larger tyres are far more of a plus than a minus in
minimising the stresses as the larger diameter and surface area tend to
'smooth' out the road ahead.

Cheers

Alister

----- Original Message -----
From: Ralph Baker <rbaker@sumter.net>
To: <murphy-rebel@dcsol.com>
Sent: Sunday, October 22, 2000 8:45 AM
Subject: New Rebel with spring gear.

There an offsetting factors regarding larger tires that have not been
mentioned.
1- Larger diameter tires increase the lever arm through which the
retarding (braking) force is transmitted to the
ground. Said simply, for equivalent brake pedal pressure there is less
slowing effect with the larger tires. This will result in less torque on
the gear. Of course, with greater pedal pressure there is a "crossover
point" where the greater pedal pressure will increase the gear leg torque
above "standard".
2- Braking effects aside, the larger diameter tires will climb out of
holes and over obstacles more easily than smaller diameter. Ask any dirt
biker about using a 21" front tire versus an 18" tire in the rough.
3- The larger tires are normally run at lower tire pressures and as such
will absorb more jolts and transmit less peak force to the gear and thence
to the fuselage. Like a recoil pad on a rifle, the energy doesn't change,
it is just spread out over a longer time.
4- From the "no free lunch" department, the larger tires will cost some
cruise speed.

For what it's worth, we're putting the 8:00x6 main tires and SR tail tire
on our Elite. This will primarily be used in Idaho and Montana

backcountry

and for us the positives predominate. May get a spare rim set and 6:00x6
tires for estimated increase 4-7 mph for the long trips.

Ralph Baker / Sue Scouten
Furiously building Elite 611E in South Carolina so we can move West.

*---------------------------------------------------------------------------
--------*

The Murphy Rebel Builders List is for the discussion
between builders and owners of Murphy Rebel aircraft.
Archives located at:
http://www.dcsol.com/murphy-rebel/lists/default.htm

*---------------------------------------------------------------------------
--------*

*-----------------------------------------------------------------------------------*
The Murphy Rebel Builders List is for the discussion
between builders and owners of Murphy Rebel aircraft.
Archives located at:
http://www.dcsol.com/murphy-rebel/lists/default.htm
*-----------------------------------------------------------------------------------*

-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
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