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1. 03:20 AM - Re: Propeller diameter (Karl Heindl)
2. 05:57 AM - Thanks Bud (William Daniell)
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| Subject: | RE: Propeller diameter |
The recommended prop diameter maximum can be extended by replacing the nose
gear shaft with a longer one. My propeller is 69 inches without any loss o
f ground clearance. This clearance is vital when operating from a bumpy and
/or soft field and should be at least 12 inches.
Karl
From: budyerly@msn.com
Subject: Re: Europa-List:
Will=2C
Max prop diameter is still 64 inches recommended. This is based on
the prop clearance of course. In the tri gear clearances are based
on spring or bungee with the by the book cable stop dimensions per the
build manual. This leaves nominally 10-11 inches from the prop
tip to the ground (aircraft unloaded=2C nose tire inflated at 35 psi. and t
he
CG at 60 inches) in most of my aircraft. At full
deflection of the gear at full gross weight=2C this gives 7-8 inches of
clearance. (Yours may be different due to main gear installation.)
FAA requirements for minimum propeller clearance:
Sec. 25.925
Propeller clearance.
Unless smaller clearances are
substantiated=2C propeller clearances with
the
airplane at maximum weight=2C with the most adverse center of gravity=2C
and with
the propeller in the most adverse pitch position=2C may not be less
than the
following:
(a) Ground clearance. There must be a
clearance of at least seven inches
(for each airplane with nose wheel
landing gear) or nine inches (for each
airplane with tail wheel landing
gear) between each propeller and the ground
with landing gear statically
deflected and in the level takeoff=2C or taxiing attitude=2C
whichever is most
critical. In addition=2C there must be positive clearance
between the
propeller and the ground when in the level takeoff attitude
with the
critical [tire(s)] completely deflated and the corresponding
landing
gear strut bottomed.
Europa nominal clearances:
If installed by the book at 2 inches (full cable extension)=2C
crossed properly so the cable cannot slip off=2C with
a deflated nose gear tire=2C there is at least 4 inches of clearance
on my new builds putting a full 300 pounds on the front of the engine.
That will keep you from mowing the grass and or plowing a furrow with your
64
inch propeller if the nose gear tire fails on a rough landing or rough
strip.
12 AY flew with the gear leg bolted solid in an attempt to install a longer
prop. I don't recommend it. It's a bit harsh on a rough
strip so to prevent fatigue I installed the springs shortly thereafter and
shortened my cable stop to allow a total of 1 inch of movement until
contact and a bit more on full extension.
Longer answer on install and extended life operations
notes:
On installation=2C Chapter 29T says to pull the gear leg
up (without springs or bungee) and swag the cable at two inches from the
stop to the leg. I clamp (using a bolt type cable clamp) the cable at
that distance with the gear leg pulled to check full tension on the
cable. When satisfied=2C I then swag the cable. This gives 8
inches clearance as stated above.
In the field=2C because the spring or bungee is attached normally=2C I use
the one inch (two fingers) method to check if I need to re-swag the cable
because of poor installation or cable stretch. I find the cable easy
to pull down firmly from under the aircraft and check the distance. To
check the springs I place my full body weight (180 lbs.) at the
hub to deflect the springs the full amount for a quick check. When
doing maintenance on other aircraft I have found that the cable
will stretch a bit more than new which puts more strain on the
springs. Occasionally I have seen on trigears which have operated
extensively on grass=2C and the cable stop either was installed
improperly or it had loosened and had not worked as advertised (it slipped
off
the lower leg) and this caused the springs to become weaker under severe
grass strip operations. (Thirty pounds at the hub caused the springs to
deflect which is unacceptable.) It is not fun to cut those springs off and
replace them because they no longer hold the nose gear firmly on the stop.
So it was a personal decision to go tighter than looser on the cable stop t
o
prevent this from happening.
Regards=2C
Bud Yerly
Europa Tech Support
813 244-8354
----- Original Message -----
From: William Daniell
To: europa-list@matronics.com
Sent: Tuesday=2C December 20=2C 2011 8:34
AM
Subject: Europa-List:
I am sure that this has been posted many time but to avoid
having to hunt through the archives - what is the max prop diameter for a
Trigear?
Will
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Message 2
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Bud
Thanks very much - as usual a very complete answer!
Oh. and may I take the opportunity to wish you a very prosperous,
successful and above all safe 2012.
Yours
Will
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Bud Yerly
Sent: 26 December, 2011 17:19
Subject: Re: Europa-List:
Will,
Max prop diameter is still 64 inches recommended. This is based on the prop
clearance of course. In the tri gear clearances are based on spring or
bungee with the by the book cable stop dimensions per the build manual.
This leaves nominally 10-11 inches from the prop tip to the ground (aircraft
unloaded, nose tire inflated at 35 psi. and the CG at 60 inches) in most of
my aircraft. At full deflection of the gear at full gross weight, this
gives 7-8 inches of clearance. (Yours may be different due to main gear
installation.)
FAA requirements for minimum propeller clearance:
Sec. 25.925
Propeller clearance.
Unless smaller clearances are substantiated, propeller clearances with the
airplane at maximum weight, with the most adverse center of gravity, and
with
the propeller in the most adverse pitch position, may not be less than the
following:
(a) Ground clearance. There must be a clearance of at least seven inches
(for each airplane with nose wheel landing gear) or nine inches (for each
airplane with tail wheel landing gear) between each propeller and the ground
with landing gear statically deflected and in the level takeoff, or taxiing
attitude,
whichever is most critical. In addition, there must be positive clearance
between the propeller and the ground when in the level takeoff attitude
with the critical [tire(s)] completely deflated and the corresponding
landing
gear strut bottomed.
Europa nominal clearances:
If installed by the book at 2 inches (full cable extension), crossed
properly so the cable cannot slip off, with a deflated nose gear tire, there
is at least 4 inches of clearance on my new builds putting a full 300 pounds
on the front of the engine. That will keep you from mowing the grass and or
plowing a furrow with your 64 inch propeller if the nose gear tire fails on
a rough landing or rough strip.
12 AY flew with the gear leg bolted solid in an attempt to install a longer
prop. I don't recommend it. It's a bit harsh on a rough strip so to
prevent fatigue I installed the springs shortly thereafter and shortened my
cable stop to allow a total of 1 inch of movement until contact and a bit
more on full extension.
Longer answer on install and extended life operations notes:
On installation, Chapter 29T says to pull the gear leg up (without springs
or bungee) and swag the cable at two inches from the stop to the leg. I
clamp (using a bolt type cable clamp) the cable at that distance with the
gear leg pulled to check full tension on the cable. When satisfied, I then
swag the cable. This gives 8 inches clearance as stated above.
In the field, because the spring or bungee is attached normally, I use the
one inch (two fingers) method to check if I need to re-swag the cable
because of poor installation or cable stretch. I find the cable easy to
pull down firmly from under the aircraft and check the distance. To check
the springs I place my full body weight (180 lbs.) at the hub to deflect the
springs the full amount for a quick check. When doing maintenance on other
aircraft I have found that the cable will stretch a bit more than new which
puts more strain on the springs. Occasionally I have seen on trigears which
have operated extensively on grass, and the cable stop either was installed
improperly or it had loosened and had not worked as advertised (it slipped
off the lower leg) and this caused the springs to become weaker under severe
grass strip operations. (Thirty pounds at the hub caused the springs to
deflect which is unacceptable.) It is not fun to cut those springs off and
replace them because they no longer hold the nose gear firmly on the stop.
So it was a personal decision to go tighter than looser on the cable stop to
prevent this from happening.
Regards,
Bud Yerly
Europa Tech Support
813 244-8354
----- Original Message -----
From: William Daniell <mailto:wdaniell@etb.net.co>
Sent: Tuesday, December 20, 2011 8:34 AM
Subject: Europa-List:
I am sure that this has been posted many time but to avoid having to hunt
through the archives - what is the max prop diameter for a Trigear?
Will
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href="http://www.matronics.com/contribution">http://www.matronics.com/c
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