Today's Message Index:
----------------------
1. 12:37 AM - Re: Thrust - Over Rated (Michael Gibbs)
2. 03:54 AM - Re: Re: Elevator hinge tab question?? (Lynn Matteson)
3. 04:40 AM - Re: 912S/ oil cooler efficiency (Fox5flyer)
4. 06:14 AM - Kitfox for sale (Gill Levesque)
5. 06:32 AM - Re: Re: Thrust - Over Rated (Randy Daughenbaugh)
6. 08:11 AM - Re: 912S/ oil cooler efficiency (Fred Shiple)
7. 10:19 AM - Re: Grounding of fuel tanks (Donald STEVENSON)
8. 10:47 AM - Re: Bing 54 Choke cable adjustment?? (Jim Burke)
9. 01:18 PM - Re: Tundra tyres. (Michel Verheughe)
10. 04:24 PM - Re: Kitfox for sale (John Anderson)
11. 04:24 PM - Re: Re: Thrust - Over Rated (John Anderson)
12. 04:59 PM - Hydraulic brakes (Malcolmbru@AOL.COM)
13. 05:24 PM - Re: Kitfox for sale (Gill Levesque)
14. 05:24 PM - Re: Hydraulic brakes (RAY Gignac)
15. 05:26 PM - Re: Hydraulic brakes (Rexster)
16. 05:30 PM - Re: Tundra tyres. (RAY Gignac)
17. 05:41 PM - Re: Re: Thrust - Over Rated (wingsdown)
18. 07:18 PM - Re: Re: Thrust - Over Rated (John Anderson)
19. 07:25 PM - Re: Re: Thrust - Over Rated (John Anderson)
20. 07:44 PM - Re: Re: Thrust - Over Rated (wingsdown)
21. 08:06 PM - Re: Hydraulic brakes (Mike Ford)
22. 08:25 PM - Re: Bing 54 Choke adjustment (Guy Buchanan)
23. 08:43 PM - Re: Hydraulic brakes (kurt schrader)
24. 08:46 PM - Re: Re: Thrust - Over Rated (kurt schrader)
25. 09:07 PM - Re: Hydraulic brakes (Lowell Fitt)
26. 10:14 PM - Re: Re: Thrust - Over Rated (kurt schrader)
27. 10:24 PM - Re: Re: Thrust - Over Rated (kurt schrader)
28. 11:06 PM - Re: Re: Thrust - Over Rated (kurt schrader)
29. 11:16 PM - Re: Thrust...Overrated? (kurt schrader)
Message 1
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| Subject: | Re: Thrust - Over Rated |
--> Kitfox-List message posted by: Michael Gibbs <MichaelGibbs@cox.net>
Kurt sez:
> My flame suite on for another long one...
> :
> :
> When I flew the C-130, the pitch could be as high as...
> :
> :
> So I am saying this. The prop that produces the most...
> :
> :
> So that is why I wanted a meter that simply measures...
> :
> :
> Is this too much at once? Hope it can be understood...
> :
> :
> One day I will simplify this...
Reminds me of something Mark Twain once wrote: "I apologize for such
a long letter, I didn't have time to write a short one." :-)
Mike G.
N728KF
Message 2
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| Subject: | Re: Elevator hinge tab question?? |
--> Kitfox-List message posted by: Lynn Matteson <lynnmatt@jps.net>
I'm curious as to how you got the chuck of the flex shaft to clear the
elevator tube on the elevator tabs that are in the middle of the
elevator?
I couldn't find anything that would clear this area, hence my making
the 8-foot-long reamer.
Lynn
On Tuesday, May 9, 2006, at 11:30 PM, darinh wrote:
> --> Kitfox-List message posted by: "darinh" <gerns25@netscape.net>
>
> Thanks to all who responded. I have solved the problem using a nifty
> little gadget I picked up at the local Lowe's. It is a flexibly drill
> shaft. I simply installed a 13/64 bit and drilled out the elevator
> tabs to allow for 1/32" oversized hole. The elevator went together
> excellent and works great! Thanks again,
>
> Darin
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=33749#33749
>
>
Message 3
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| Subject: | Re: 912S/ oil cooler efficiency |
--> Kitfox-List message posted by: "Fox5flyer" <morid@northland.lib.mi.us>
I can't help with the oil temps Fred, but congrats on getting the floats in
the air. How's the teething process going?
Deke
----- Original Message -----
From: "Fred Shiple" <fredshiple@sbcglobal.net>
Sent: Tuesday, May 09, 2006 9:52 PM
Subject: Kitfox-List: 912S/ oil cooler efficiency
> --> Kitfox-List message posted by: Fred Shiple <fredshiple@sbcglobal.net>
>
> I've a question regarding oil cooler efficiency on a Kitfox with a 912S:
> My Series 6/ 912S was built with the Skystar optional oil cooler. During
the past two summers at temps over 95F I'd have to lower the nose after talk
off/climb after about 1 to 1 1/2 minutes as oil temp reached 260F (red line
266F). At 100F (a rare occurance in NW Ohio) had to throttle back from 75%
to 65% for the same reason.
> Now that I'm flying on floats, I've begun to see the same thing at 75-80
degrees. I'm flying 12-15 mph slower (at the same rpm/manifold pressures)
as anticipated with the extra drag. The water and cylinder head temps have
remained well in the green with or without the floats. I saw temps
consistant with prior years operations in the month prior to install of the
floats two weeks ago.
> Any advice is appreciated as I'm now concerned about warmer weather
operation.
> Fred
>
>
Message 4
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--> Kitfox-List message posted by: Gill Levesque <canpilot03@yahoo.ca>
Hi All,
Due to unforseen circumstances I sadly announce that my beloved Kitfox is for
sale!
. 100hrs. TTAE, 582 grey head with 3:1 redrive ,no spinner.
factory refinished GSC three blade prop(sept/05)
Factory custom seat cover,baggage sack and cover,door and windshield post
panels, carpet kick panels, nice panel with AS,ALT,VSI,Quad EGT/CHT,slip indicator,2
Tachs,water temp, ELT remote, Garmin 12 GPS, Panel mounted Delcom radio,
wing strut cuffs, wing tip strobes,Tinted Lexan all around ! Always hangered!
A good looking and great flying ( cruise 95 mph ind. solo!!) plane!
Plane is in Southern Ontario Canada
$27,500.00 CAN
Email me off list for pics and any questions
Gil Levesque
C-IGVL
---------------------------------
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Message 5
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| Subject: | Re: Thrust - Over Rated |
--> Kitfox-List message posted by: "Randy Daughenbaugh" <rjdaugh@rapidnet.com>
Thanks Kurt! As usual, another great post.
Maybe you can shed some light on my following comment.
You want to get the rpm's up on takeoff so you can use the power, but you
want to have more pitch for more thrust at speed. You can approach this
with an in-flight adjustable prop, or you can get close by having a prop
that "slips" during take off, letting the engine rev up, but still has
enough pitch to make some thrust at speed.
I think this is a difference between the skinny blades of the warp drive and
wide, high lift blades of the Powerfin. My CFI friend (16,000 hours) was
impressed, but not favorably, on how my Powerfin prop was "connected" to the
air. Engine rpm was not determined as much by throttle position as by
airspeed. In my plane, he was trying to teach me to set rpm to certain
number at different points in the approach. This works on his plane with
the Warp drive. But with the powerfin, you can pull the power off but
unless you slow the plane, the rpm doesn't change. The powerfin does make a
great brake.
So is "prop slip" part of the formula in getting a prop to best fit torque,
and power?
Randy
.
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of kurt schrader
Sent: Tuesday, May 09, 2006 6:35 PM
Subject: Re: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: kurt schrader
<smokey_bear_40220@yahoo.com>
My flame suite on for another long one.....
---------------------------------
> Randy sez:
>
> >In short, if you want more thrust, all you have to
> >do is sacrifice top speed. Therefore, thrust is
> >irrelevant.
> -------------------------
> Mike G.
> N728KF
> If you want more thrust AND more top speed, you get
> an in-flight adjustable prop. You wouldn't drive
> your car in one gear all the time, why operate your
> airplane that way?
----------------------------
Good point Mike,
There is a misunderstanding on the list of thrust, HP
and torque. The whole purpose of the prop is to
convert power into thrust. Thrust is the most
relevant measure. It moves the plane.
But we are not talking about static thrust. You need
the best thrust at the speed you are flying for best
performance. Max static thrust is best at zero speed
only. Max takeoff thrust is best somewhere around 1/2
your takeoff speed. Max climb thrust is best at climb
speed. Max cruise thrust is best at.... ahhh you get
it.
A fixed pitch prop will give you its max thrust at
only one speed. You are compromising only in that you
pick the speed you want to have it perform best at.
At all other speeds, faster or slower, it will give
less then max thrust.
A variable or constant speed prop will still have one
best speed, but the curve will be flatter. It will
perform almost as well at all speeds as a fixed pitch
prop for its one speed.
Say a cruise fixed pitch gives efficiencies of:
50% in takeoff
75% in climb
85% in cruise
A climb prop might give:
65% in takeoff
85% in climb
80% in cruise
The variable prop might give:
75% in takeoff
82% in climb
83% in cruise
I have a friend who has a Champ product, his 3rd in 2
years. His 150 HP constant speed Champ would perform
equal to his 180 HP fixed pitch Champ, except around
one speed. That speed depended upon which fixed pitch
prop he installed. He might get better climb, but
equal cruise, or better cruise, but equal climb from
the extra 30 HP.
In his case, he used the prop that meant they cruised
equally, but the fixed pitch climbed better with the
30 more HP. If it had a constant speed prop, it would
have used the 30 extra HP for better performance all
across the speed range. His fixed pitch got off the
ground better, but burned more for the same cruise
speed.
Another way to say it is that the variable prop was
almost worth the 30 extra HP.
This is my problem with static thrust measurements.
It only gives you the measurement for the best prop at
no speed. How useful is that? I think that is what
Randy was saying.
Static thrust is only good when static. It is already
losing performance in the takeoff roll, but not so
badly as when at cruise speed. A cruise prop would be
poor but increasing performance in the takeoff roll,
and continue to get better all the way up to cruise.
The climb prop is of course in between, getting
better, then getting worse as speed increases.
As to HP and torque, if you are swinging a 2x4 around
with your engine, it will take HP and torque to do,
but produce no thrust. If you have a feathered prop,
it will take lots of HP and torque to swing and still
produce no thrust. The efficiency of the prop to
produce thrust is what makes the hp and torque
meaningful.
As a prop increases pitch, it moves more toward a
feathered prop in that the angle of lift of the prop
is more against torque and less forward producing
thrust. Lift of the prop is always about 90 degrees
to the blade. A pitch of say 20 degrees means that
some of the prop's lift is pulling air in a circle and
not just pushing it back. That takes HP.
When I flew the C-130, the pitch could be as high as
55 degrees in cruise. More than 1/2 the HP went to
spinning the air and less than 1/2 went to thrust.
Our props don't get that bad due to our less pitch.
But a heavily pitched prop may take the same HP/torque
as a finer pitched prop at higher RPM. The faster
turning, lower pitched prop will produce more thrust,
to a point. That point is determined by the most
efficient rpm for the prop compared to mach number,
and the most efficient rpm for the engine. Those 2
may not match.
A less efficient prop may take more HP or torque to
give the same performance, not more. A more efficient
prop will give more thrust with the same HP/torque.
HP and torque don't tell the whole story. They don't
give thrust, except as the prop allows.
So I am saying this. The prop that produces the most
thrust will be the one that has its best speed closest
to your engine's favorite RPM, but does it at the
speed you are flying. Also it has to be the most
aerodynamically efficient.
Max static thrust equals first gear only. Takeoff
props equal second gear. Climb props equal third
gear. Cruise props are overdrive. Variable props are
automatic trannys. That is Mike's point.
The actual performance of the plane will be determined
by just how much thrust it can produce today on this
fuel, at this temp, at this density altitude, with
this prop, at this speed, with these sparkplugs, at
this rpm and manifold setting..... You can measure
all that, or you can just measure thrust.
So thrust is really the key, but it has to be measured
now, at your speed and with all variables.
Static thrust is good for fans, not planes.
Thrust is what happens after all the variables are in
place. HP and torque are only what you are putting
into a prop, not what is coming out, which changes
with prop efficiency, speed, air density.....
So that is why I wanted a meter that simply measures
the thrust output on board at all speeds, altitudes,
settings, etc. It will tell you what performance you
are getting now, whatever now is.
And instead of HP, you can simply measure fuel flow if
the engine is tuned right. That is, if the fuel air
ratio is the same, fuel in equals power out.
That you can compare to whatever you want to change
and see if it made things better or worse. 10% more
thrust with the same fuel flow is 10% better no matter
how you got it. 10% more HP or 10% more torque might
just mean a 10% worse prop is giving equal thrust for
more gas.
Bottom line: Thrust = performance. Fuel flow =
energy and $ in to produce the thrust. The best prop
will be the one that gives you the most thrust per
fuel flow at the speed you want it.
A fixed pitch will peak at a given speed with a strong
curve. A variable prop will have a broader curve.
You have to pick the prop that peaks at the speed and
rpm that best matches your engine and most important
performance goal. This is critical for fixed pitch,
but less critical for variable.
Then you can compare one prop against another to see
which gives the most thrust at the same fuel flow.
Is this too much at once? Hope it can be understood.
You want thrust. Thrust moves the plane. We just
aren't use to measuring it directly. Fuel flow is
what we pay to get it and max fuel flow is how much
power is available under present conditions.
One day I will simplify this.....
Kurt S. S-5 flying and 1/2 done.
__________________________________________________
Message 6
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| Subject: | Re: 912S/ oil cooler efficiency |
--> Kitfox-List message posted by: Fred Shiple <fredshiple@sbcglobal.net>
Hi, Deke,
The plane/floats are flying well. The pilots doing better ;). A Kitfox on floats
is as much fun as I've ever had flying. I'll get some pictures on the site
once I get the trim painted- too busy flying now.
Fred
I can't help with the oil temps Fred, but congrats on getting the floats in
the air. How's the teething process going?
Deke
Message 7
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| Subject: | Re: Grounding of fuel tanks |
--> Kitfox-List message posted by: Donald STEVENSON <shericom@rogers.com>
Hi Lynn, I finally tried to install the ground braid to the filler neck only to
discover the tanks I have are fitted with aluminium filler necks, so much for
soldering to them, I'll have to find some other way to connect the ground,
Thanks for you help, Don
Lynn Matteson <lynnmatt@jps.net> wrote: --> Kitfox-List message posted by: Lynn
Matteson
That might have been me, Don. I used the Aircraft Spruce 1/4" tin
plated copper braid p/n 863, p.419. I attached it to the spar with a
ring terminal under a washer, then the spar attaching nut. I soldered
the braid to the filler neck, being careful to put it low enough to
clear the filler cap. I used a 200-watt soldering iron to do the job.
Lynn
On Friday, April 28, 2006, at 04:39 PM, Donald STEVENSON wrote:
> --> Kitfox-List message posted by: Donald STEVENSON
>
>
> Some weeks ago I saw discussions on grounding of the filler neck on
> the fiberglass fuel tanks (M4) to the rear spar with copper braid. My
> question is what size brade is required and how is it connected to the
> spar? I beleave it was soldered to the tank neck. Thanks in advance,
> Don
>
> Don Stevenson, Caledon, Ontario, Canada
> M4/1200-912s Speedster
>
>
Message 8
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| Subject: | Re: Bing 54 Choke cable adjustment?? |
--> Kitfox-List message posted by: "Jim Burke" <jeburke94je@hughes.net>
I sure could use some help,Can someone tell me the proper way to adjust the
cables on the Bing 54 Carb.for the
> new chokes? I don't want them to stand open or maybe not open at all when
> the choke is pulled.
> The springs in the new chokes are about twice as strong as the ones
> in the old chokes. Is this a upgrade in the chokes so they seal better? or
> should I use the old springs? I had to make a tool to compress the new
> springs so I could install the ends on the choke cable.
>
> Thanks for your input,
>
> Jim N94
Message 9
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| Subject: | Re: Tundra tyres. |
--> Kitfox-List message posted by: Michel Verheughe <michel@online.no>
Thank you for your help, guys.
Skyflyte, how long have you had those bumps in your tyres? Have you
tried to inflate them hard, as Kurt suggests it? Rex, thanks for the
"googling" I read all of the links.
I will eventually remove the tyres and find out what is the problem.
But right now, I have difficulties to understand how a fold in the
inner tube can produce what I see. But I am still a very young pilot
and I have much to learn.
Of course, I'll let everyone informed of my findings, once the tyre are
removed and inspected.
Cheers,
Michel
do not archive
Message 10
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--> Kitfox-List message posted by: "John Anderson" <janderson412@hotmail.com>
What model is it Gil?
From: Gill Levesque <canpilot03@yahoo.ca>
Subject: Kitfox-List: Kitfox for sale
--> Kitfox-List message posted by: Gill Levesque <canpilot03@yahoo.ca>
Hi All,
Due to unforseen circumstances I sadly announce that my beloved Kitfox is
for sale!
. 100hrs. TTAE, 582 grey head with 3:1 redrive ,no spinner.
factory refinished GSC three blade prop(sept/05)
Factory custom seat cover,baggage sack and cover,door and windshield
post panels, carpet kick panels, nice panel with AS,ALT,VSI,Quad
EGT/CHT,slip indicator,2 Tachs,water temp, ELT remote, Garmin 12 GPS, Panel
mounted Delcom radio, wing strut cuffs, wing tip strobes,Tinted Lexan all
around ! Always hangered!
A good looking and great flying ( cruise 95 mph ind. solo!!) plane!
Plane is in Southern Ontario Canada
$27,500.00 CAN
Email me off list for pics and any questions
Gil Levesque
C-IGVL
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_________________________________________________________________
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Message 11
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| Subject: | Re: Thrust - Over Rated |
--> Kitfox-List message posted by: "John Anderson" <janderson412@hotmail.com>
Or you can turbo charge. This sort of does what a VPP does to a degree in
that the RPM doesn't have to alter too much to increase power for t/off. You
can set the prop at a courser angle and increase boost for t/off. John A.
From: "Randy Daughenbaugh" <rjdaugh@rapidnet.com>
Subject: RE: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: "Randy Daughenbaugh"
<rjdaugh@rapidnet.com>
Thanks Kurt! As usual, another great post.
Maybe you can shed some light on my following comment.
You want to get the rpm's up on takeoff so you can use the power, but you
want to have more pitch for more thrust at speed. You can approach this
with an in-flight adjustable prop, or you can get close by having a prop
that "slips" during take off, letting the engine rev up, but still has
enough pitch to make some thrust at speed.
I think this is a difference between the skinny blades of the warp drive and
wide, high lift blades of the Powerfin. My CFI friend (16,000 hours) was
impressed, but not favorably, on how my Powerfin prop was "connected" to the
air. Engine rpm was not determined as much by throttle position as by
airspeed. In my plane, he was trying to teach me to set rpm to certain
number at different points in the approach. This works on his plane with
the Warp drive. But with the powerfin, you can pull the power off but
unless you slow the plane, the rpm doesn't change. The powerfin does make a
great brake.
So is "prop slip" part of the formula in getting a prop to best fit torque,
and power?
Randy
.
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of kurt schrader
Sent: Tuesday, May 09, 2006 6:35 PM
Subject: Re: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: kurt schrader
<smokey_bear_40220@yahoo.com>
My flame suite on for another long one.....
---------------------------------
>Randy sez:
>
> >In short, if you want more thrust, all you have to
> >do is sacrifice top speed. Therefore, thrust is
> >irrelevant.
>-------------------------
>Mike G.
>N728KF
>If you want more thrust AND more top speed, you get
>an in-flight adjustable prop. You wouldn't drive
>your car in one gear all the time, why operate your
>airplane that way?
----------------------------
Good point Mike,
There is a misunderstanding on the list of thrust, HP
and torque. The whole purpose of the prop is to
convert power into thrust. Thrust is the most
relevant measure. It moves the plane.
But we are not talking about static thrust. You need
the best thrust at the speed you are flying for best
performance. Max static thrust is best at zero speed
only. Max takeoff thrust is best somewhere around 1/2
your takeoff speed. Max climb thrust is best at climb
speed. Max cruise thrust is best at.... ahhh you get
it.
A fixed pitch prop will give you its max thrust at
only one speed. You are compromising only in that you
pick the speed you want to have it perform best at.
At all other speeds, faster or slower, it will give
less then max thrust.
A variable or constant speed prop will still have one
best speed, but the curve will be flatter. It will
perform almost as well at all speeds as a fixed pitch
prop for its one speed.
Say a cruise fixed pitch gives efficiencies of:
50% in takeoff
75% in climb
85% in cruise
A climb prop might give:
65% in takeoff
85% in climb
80% in cruise
The variable prop might give:
75% in takeoff
82% in climb
83% in cruise
I have a friend who has a Champ product, his 3rd in 2
years. His 150 HP constant speed Champ would perform
equal to his 180 HP fixed pitch Champ, except around
one speed. That speed depended upon which fixed pitch
prop he installed. He might get better climb, but
equal cruise, or better cruise, but equal climb from
the extra 30 HP.
In his case, he used the prop that meant they cruised
equally, but the fixed pitch climbed better with the
30 more HP. If it had a constant speed prop, it would
have used the 30 extra HP for better performance all
across the speed range. His fixed pitch got off the
ground better, but burned more for the same cruise
speed.
Another way to say it is that the variable prop was
almost worth the 30 extra HP.
This is my problem with static thrust measurements.
It only gives you the measurement for the best prop at
no speed. How useful is that? I think that is what
Randy was saying.
Static thrust is only good when static. It is already
losing performance in the takeoff roll, but not so
badly as when at cruise speed. A cruise prop would be
poor but increasing performance in the takeoff roll,
and continue to get better all the way up to cruise.
The climb prop is of course in between, getting
better, then getting worse as speed increases.
As to HP and torque, if you are swinging a 2x4 around
with your engine, it will take HP and torque to do,
but produce no thrust. If you have a feathered prop,
it will take lots of HP and torque to swing and still
produce no thrust. The efficiency of the prop to
produce thrust is what makes the hp and torque
meaningful.
As a prop increases pitch, it moves more toward a
feathered prop in that the angle of lift of the prop
is more against torque and less forward producing
thrust. Lift of the prop is always about 90 degrees
to the blade. A pitch of say 20 degrees means that
some of the prop's lift is pulling air in a circle and
not just pushing it back. That takes HP.
When I flew the C-130, the pitch could be as high as
55 degrees in cruise. More than 1/2 the HP went to
spinning the air and less than 1/2 went to thrust.
Our props don't get that bad due to our less pitch.
But a heavily pitched prop may take the same HP/torque
as a finer pitched prop at higher RPM. The faster
turning, lower pitched prop will produce more thrust,
to a point. That point is determined by the most
efficient rpm for the prop compared to mach number,
and the most efficient rpm for the engine. Those 2
may not match.
A less efficient prop may take more HP or torque to
give the same performance, not more. A more efficient
prop will give more thrust with the same HP/torque.
HP and torque don't tell the whole story. They don't
give thrust, except as the prop allows.
So I am saying this. The prop that produces the most
thrust will be the one that has its best speed closest
to your engine's favorite RPM, but does it at the
speed you are flying. Also it has to be the most
aerodynamically efficient.
Max static thrust equals first gear only. Takeoff
props equal second gear. Climb props equal third
gear. Cruise props are overdrive. Variable props are
automatic trannys. That is Mike's point.
The actual performance of the plane will be determined
by just how much thrust it can produce today on this
fuel, at this temp, at this density altitude, with
this prop, at this speed, with these sparkplugs, at
this rpm and manifold setting..... You can measure
all that, or you can just measure thrust.
So thrust is really the key, but it has to be measured
now, at your speed and with all variables.
Static thrust is good for fans, not planes.
Thrust is what happens after all the variables are in
place. HP and torque are only what you are putting
into a prop, not what is coming out, which changes
with prop efficiency, speed, air density.....
So that is why I wanted a meter that simply measures
the thrust output on board at all speeds, altitudes,
settings, etc. It will tell you what performance you
are getting now, whatever now is.
And instead of HP, you can simply measure fuel flow if
the engine is tuned right. That is, if the fuel air
ratio is the same, fuel in equals power out.
That you can compare to whatever you want to change
and see if it made things better or worse. 10% more
thrust with the same fuel flow is 10% better no matter
how you got it. 10% more HP or 10% more torque might
just mean a 10% worse prop is giving equal thrust for
more gas.
Bottom line: Thrust = performance. Fuel flow =
energy and $ in to produce the thrust. The best prop
will be the one that gives you the most thrust per
fuel flow at the speed you want it.
A fixed pitch will peak at a given speed with a strong
curve. A variable prop will have a broader curve.
You have to pick the prop that peaks at the speed and
rpm that best matches your engine and most important
performance goal. This is critical for fixed pitch,
but less critical for variable.
Then you can compare one prop against another to see
which gives the most thrust at the same fuel flow.
Is this too much at once? Hope it can be understood.
You want thrust. Thrust moves the plane. We just
aren't use to measuring it directly. Fuel flow is
what we pay to get it and max fuel flow is how much
power is available under present conditions.
One day I will simplify this.....
Kurt S. S-5 flying and 1/2 done.
__________________________________________________
_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today - it's FREE!
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Message 12
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|
| Subject: | Hydraulic brakes |
--> Kitfox-List message posted by: Malcolmbru@aol.com
I have a KF2 finished in 1999 and can find nothing in my records on the
brakes. They are hydraulic and look like matko but they have no writing at
all
on them. They are all aluminum and the peddles look just like the ones in
the builders manual as do the axis one caliper is sticking , the rotor
gets real hot and the other is leaking rite through the wall. like a poris spot
in the aluminum What to do?
Message 13
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--> Kitfox-List message posted by: Gill Levesque <canpilot03@yahoo.ca>
Sorry John ,I forgot that It's a model 4 1050
Gil
John Anderson <janderson412@hotmail.com> wrote:
--> Kitfox-List message posted by: "John Anderson"
What model is it Gil?
From: Gill Levesque
Subject: Kitfox-List: Kitfox for sale
--> Kitfox-List message posted by: Gill Levesque
Hi All,
Due to unforseen circumstances I sadly announce that my beloved Kitfox is
for sale!
. 100hrs. TTAE, 582 grey head with 3:1 redrive ,no spinner.
factory refinished GSC three blade prop(sept/05)
Factory custom seat cover,baggage sack and cover,door and windshield
post panels, carpet kick panels, nice panel with AS,ALT,VSI,Quad
EGT/CHT,slip indicator,2 Tachs,water temp, ELT remote, Garmin 12 GPS, Panel
mounted Delcom radio, wing strut cuffs, wing tip strobes,Tinted Lexan all
around ! Always hangered!
A good looking and great flying ( cruise 95 mph ind. solo!!) plane!
Plane is in Southern Ontario Canada
$27,500.00 CAN
Email me off list for pics and any questions
Gil Levesque
C-IGVL
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Message 14
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|
| Subject: | Re: Hydraulic brakes |
--> Kitfox-List message posted by: "RAY Gignac" <KITFOXPILOT@msn.com>
Couple of things to look at: One of the spacers on the calipers could =
be binding and needs to be cleaned. As for the leak, O ring in the =
caliper could be bad allowing the leak and both problems are an easy =
fix. Matco sells the new O rings and new spacers if you are unable to =
clean them!
Ray
----- Original Message -----
From: Malcolmbru@aol.com<mailto:Malcolmbru@aol.com>
To: kitfox-list@matronics.com<mailto:kitfox-list@matronics.com>
Sent: Wednesday, May 10, 2006 7:57 PM
Subject: Kitfox-List: Hydraulic brakes
--> Kitfox-List message posted by: =
Malcolmbru@aol.com<mailto:Malcolmbru@aol.com>
I have a KF2 finished in 1999 and can find nothing in my records on =
the
brakes. They are hydraulic and look like matko but they have no =
writing at all
on them. They are all aluminum and the peddles look just like the =
ones in
the builders manual as do the axis one caliper is sticking , the =
rotor
gets real hot and the other is leaking rite through the wall. like a =
poris spot
in the aluminum What to do?
=
=
http://www.matronics.com/Navigator?Kitfox-List<http://www.matronics.com/N=
avigator?Kitfox-List>
=
=
=
=
http://www.matronics.com/contribution<http://www.matronics.com/contributi=
on>
=
=
Message 15
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|
| Subject: | Re: Hydraulic brakes |
--> Kitfox-List message posted by: "Rexster" <runwayrex@juno.com>
Those probably are Matco brakes. I changed from Matco to Cleveland and w=
as very impressed with the difference. With the Matco brakes, some peopl=
e were breaking rudder pedals trying to hold the plane during run-ups. W=
ith the Clevelands, rudder pedal forces were greatly reduced. That's my =
experience.
Rex Phelps/ Michigan
-- Malcolmbru@aol.com wrote:
--> Kitfox-List message posted by: Malcolmbru@aol.com
I have a KF2 finished in 1999 and can find nothing in my records on the=
=
brakes. They are hydraulic and look like matko but they have no writ=
ing at all =
on them. They are all aluminum and the peddles look just like the on=
es in =
the builders manual as do the axis one caliper is sticking , the roto=
r =
gets real hot and the other is leaking rite through the wall. like a po=
ris spot =
in the aluminum What to do? =
=
=
=
=
=
=
=
<html><P>Those probably are Matco brakes. I changed from Matco to Clevel=
and and was very impressed with the difference. With the Matco brakes, s=
ome people were breaking rudder pedals trying to hold the plane during r=
un-ups. With the Clevelands, rudder pedal forces were greatly reduced. T=
hat's my experience.</P>
<P>Rex Phelps/ Michigan</P>
<P><BR><BR>-- Malcolmbru@aol.com wrote:<BR>--> Kitfox-=
List message posted by: Malcolmbru@aol.com<BR><BR>I&=
nbsp;have a KF2 finished in 1999 and =
can find nothing in my records on&nb=
sp;the <BR>brakes. They are hydraulic&nb=
sp;and look like matko but they&nbs=
p;have no writing at all <BR>on them. =
; They are all aluminum and th=
e peddles look just like the ones&nb=
sp;in <BR>the builders manual as do =
the axis one caliper is sticking&nb=
sp;, the rotor <BR>gets real hot and=
the other is leaking rite through th=
e wall. like a poris spot <BR>in &nbs=
p;the aluminum What to do? <BR><BR><BR><B=
=
sp; - The Kitfox-List =
bsp;many List utilities such as the Subscr=
=
=
=
=
=
sp; - NEW MATRONICS LIST&nbs=
nbsp; &=
nbsp; &=
nbsp; &=
=
=
bsp; Thank you for your generous sup=
p; &nbs=
p; -Matt Dralle,&nbs=
=
<BR><BR><BR><BR> =
;<BR> <BR> <BR><BR><BR><BR></P></html>
Message 16
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|
| Subject: | Re: Tundra tyres. |
--> Kitfox-List message posted by: "RAY Gignac" <KITFOXPILOT@msn.com>
I wanted to add my thoughts on the tire issue! I searched high and low =
for similar tires like the old slick tires sold by Denney years ago, I =
have used turf glide on the old style ATV wheel and on my Matco 6" split =
wheel! I decided to go to Air Tacs on my split wheels, and I am glad I =
did so much better. Here is my set up: Matco 6" split wheel with 600x6 =
air trac tires. Still using the original Matco brakes.
Ray
Model IV 1200, 912ULS
----- Original Message -----
From: Michel Verheughe<mailto:michel@online.no>
To: kitfox-list@matronics.com<mailto:kitfox-list@matronics.com>
Sent: Wednesday, May 10, 2006 4:10 PM
Subject: Re: Kitfox-List: Tundra tyres.
--> Kitfox-List message posted by: Michel Verheughe =
<michel@online.no<mailto:michel@online.no>>
Thank you for your help, guys.
Skyflyte, how long have you had those bumps in your tyres? Have you
tried to inflate them hard, as Kurt suggests it? Rex, thanks for the
"googling" I read all of the links.
I will eventually remove the tyres and find out what is the problem.
But right now, I have difficulties to understand how a fold in the
inner tube can produce what I see. But I am still a very young pilot
and I have much to learn.
Of course, I'll let everyone informed of my findings, once the tyre =
are
removed and inspected.
Cheers,
Michel
do not archive
=
=
http://www.matronics.com/Navigator?Kitfox-List<http://www.matronics.com/N=
avigator?Kitfox-List>
=
=
=
=
http://www.matronics.com/contribution<http://www.matronics.com/contributi=
on>
=
=
Message 17
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|
| Subject: | Re: Thrust - Over Rated |
--> Kitfox-List message posted by: "wingsdown" <wingsdown@comcast.net>
Excellent point John.
Rick
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of John
Anderson
Sent: Wednesday, May 10, 2006 4:21 PM
Subject: RE: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: "John Anderson"
--> <janderson412@hotmail.com>
Or you can turbo charge. This sort of does what a VPP does to a degree
in
that the RPM doesn't have to alter too much to increase power for t/off.
You
can set the prop at a courser angle and increase boost for t/off. John
A.
From: "Randy Daughenbaugh" <rjdaugh@rapidnet.com>
Subject: RE: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: "Randy Daughenbaugh"
<rjdaugh@rapidnet.com>
Thanks Kurt! As usual, another great post.
Maybe you can shed some light on my following comment.
You want to get the rpm's up on takeoff so you can use the power, but
you
want to have more pitch for more thrust at speed. You can approach this
with an in-flight adjustable prop, or you can get close by having a prop
that "slips" during take off, letting the engine rev up, but still has
enough pitch to make some thrust at speed.
I think this is a difference between the skinny blades of the warp drive
and
wide, high lift blades of the Powerfin. My CFI friend (16,000 hours)
was
impressed, but not favorably, on how my Powerfin prop was "connected" to
the
air. Engine rpm was not determined as much by throttle position as by
airspeed. In my plane, he was trying to teach me to set rpm to certain
number at different points in the approach. This works on his plane
with
the Warp drive. But with the powerfin, you can pull the power off but
unless you slow the plane, the rpm doesn't change. The powerfin does
make a
great brake.
So is "prop slip" part of the formula in getting a prop to best fit
torque,
and power?
Randy
.
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of kurt
schrader
Sent: Tuesday, May 09, 2006 6:35 PM
Subject: Re: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: kurt schrader
<smokey_bear_40220@yahoo.com>
My flame suite on for another long one.....
---------------------------------
>Randy sez:
>
> >In short, if you want more thrust, all you have to
> >do is sacrifice top speed. Therefore, thrust is
> >irrelevant.
>-------------------------
>Mike G.
>N728KF
>If you want more thrust AND more top speed, you get
>an in-flight adjustable prop. You wouldn't drive
>your car in one gear all the time, why operate your
>airplane that way?
----------------------------
Good point Mike,
There is a misunderstanding on the list of thrust, HP
and torque. The whole purpose of the prop is to
convert power into thrust. Thrust is the most
relevant measure. It moves the plane.
But we are not talking about static thrust. You need
the best thrust at the speed you are flying for best
performance. Max static thrust is best at zero speed
only. Max takeoff thrust is best somewhere around 1/2
your takeoff speed. Max climb thrust is best at climb
speed. Max cruise thrust is best at.... ahhh you get
it.
A fixed pitch prop will give you its max thrust at
only one speed. You are compromising only in that you
pick the speed you want to have it perform best at.
At all other speeds, faster or slower, it will give
less then max thrust.
A variable or constant speed prop will still have one
best speed, but the curve will be flatter. It will
perform almost as well at all speeds as a fixed pitch
prop for its one speed.
Say a cruise fixed pitch gives efficiencies of:
50% in takeoff
75% in climb
85% in cruise
A climb prop might give:
65% in takeoff
85% in climb
80% in cruise
The variable prop might give:
75% in takeoff
82% in climb
83% in cruise
I have a friend who has a Champ product, his 3rd in 2
years. His 150 HP constant speed Champ would perform
equal to his 180 HP fixed pitch Champ, except around
one speed. That speed depended upon which fixed pitch
prop he installed. He might get better climb, but
equal cruise, or better cruise, but equal climb from
the extra 30 HP.
In his case, he used the prop that meant they cruised
equally, but the fixed pitch climbed better with the
30 more HP. If it had a constant speed prop, it would
have used the 30 extra HP for better performance all
across the speed range. His fixed pitch got off the
ground better, but burned more for the same cruise
speed.
Another way to say it is that the variable prop was
almost worth the 30 extra HP.
This is my problem with static thrust measurements.
It only gives you the measurement for the best prop at
no speed. How useful is that? I think that is what
Randy was saying.
Static thrust is only good when static. It is already
losing performance in the takeoff roll, but not so
badly as when at cruise speed. A cruise prop would be
poor but increasing performance in the takeoff roll,
and continue to get better all the way up to cruise.
The climb prop is of course in between, getting
better, then getting worse as speed increases.
As to HP and torque, if you are swinging a 2x4 around
with your engine, it will take HP and torque to do,
but produce no thrust. If you have a feathered prop,
it will take lots of HP and torque to swing and still
produce no thrust. The efficiency of the prop to
produce thrust is what makes the hp and torque
meaningful.
As a prop increases pitch, it moves more toward a
feathered prop in that the angle of lift of the prop
is more against torque and less forward producing
thrust. Lift of the prop is always about 90 degrees
to the blade. A pitch of say 20 degrees means that
some of the prop's lift is pulling air in a circle and
not just pushing it back. That takes HP.
When I flew the C-130, the pitch could be as high as
55 degrees in cruise. More than 1/2 the HP went to
spinning the air and less than 1/2 went to thrust.
Our props don't get that bad due to our less pitch.
But a heavily pitched prop may take the same HP/torque
as a finer pitched prop at higher RPM. The faster
turning, lower pitched prop will produce more thrust,
to a point. That point is determined by the most
efficient rpm for the prop compared to mach number,
and the most efficient rpm for the engine. Those 2
may not match.
A less efficient prop may take more HP or torque to
give the same performance, not more. A more efficient
prop will give more thrust with the same HP/torque.
HP and torque don't tell the whole story. They don't
give thrust, except as the prop allows.
So I am saying this. The prop that produces the most
thrust will be the one that has its best speed closest
to your engine's favorite RPM, but does it at the
speed you are flying. Also it has to be the most
aerodynamically efficient.
Max static thrust equals first gear only. Takeoff
props equal second gear. Climb props equal third
gear. Cruise props are overdrive. Variable props are
automatic trannys. That is Mike's point.
The actual performance of the plane will be determined
by just how much thrust it can produce today on this
fuel, at this temp, at this density altitude, with
this prop, at this speed, with these sparkplugs, at
this rpm and manifold setting..... You can measure
all that, or you can just measure thrust.
So thrust is really the key, but it has to be measured
now, at your speed and with all variables.
Static thrust is good for fans, not planes.
Thrust is what happens after all the variables are in
place. HP and torque are only what you are putting
into a prop, not what is coming out, which changes
with prop efficiency, speed, air density.....
So that is why I wanted a meter that simply measures
the thrust output on board at all speeds, altitudes,
settings, etc. It will tell you what performance you
are getting now, whatever now is.
And instead of HP, you can simply measure fuel flow if
the engine is tuned right. That is, if the fuel air
ratio is the same, fuel in equals power out.
That you can compare to whatever you want to change
and see if it made things better or worse. 10% more
thrust with the same fuel flow is 10% better no matter
how you got it. 10% more HP or 10% more torque might
just mean a 10% worse prop is giving equal thrust for
more gas.
Bottom line: Thrust = performance. Fuel flow =
energy and $ in to produce the thrust. The best prop
will be the one that gives you the most thrust per
fuel flow at the speed you want it.
A fixed pitch will peak at a given speed with a strong
curve. A variable prop will have a broader curve.
You have to pick the prop that peaks at the speed and
rpm that best matches your engine and most important
performance goal. This is critical for fixed pitch,
but less critical for variable.
Then you can compare one prop against another to see
which gives the most thrust at the same fuel flow.
Is this too much at once? Hope it can be understood.
You want thrust. Thrust moves the plane. We just
aren't use to measuring it directly. Fuel flow is
what we pay to get it and max fuel flow is how much
power is available under present conditions.
One day I will simplify this.....
Kurt S. S-5 flying and 1/2 done.
__________________________________________________
_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today - it's
FREE!
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Message 18
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|
| Subject: | Re: Thrust - Over Rated |
--> Kitfox-List message posted by: "John Anderson" <janderson412@hotmail.com>
Yes Rick, I'm sure that's why I'm getting such a good result performance
wise. John
From: "wingsdown" <wingsdown@comcast.net>
Subject: RE: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: "wingsdown" <wingsdown@comcast.net>
Excellent point John.
Rick
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of John
Anderson
Sent: Wednesday, May 10, 2006 4:21 PM
Subject: RE: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: "John Anderson"
--> <janderson412@hotmail.com>
Or you can turbo charge. This sort of does what a VPP does to a degree
in
that the RPM doesn't have to alter too much to increase power for t/off.
You
can set the prop at a courser angle and increase boost for t/off. John
A.
From: "Randy Daughenbaugh" <rjdaugh@rapidnet.com>
Subject: RE: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: "Randy Daughenbaugh"
<rjdaugh@rapidnet.com>
Thanks Kurt! As usual, another great post.
Maybe you can shed some light on my following comment.
You want to get the rpm's up on takeoff so you can use the power, but
you
want to have more pitch for more thrust at speed. You can approach this
with an in-flight adjustable prop, or you can get close by having a prop
that "slips" during take off, letting the engine rev up, but still has
enough pitch to make some thrust at speed.
I think this is a difference between the skinny blades of the warp drive
and
wide, high lift blades of the Powerfin. My CFI friend (16,000 hours)
was
impressed, but not favorably, on how my Powerfin prop was "connected" to
the
air. Engine rpm was not determined as much by throttle position as by
airspeed. In my plane, he was trying to teach me to set rpm to certain
number at different points in the approach. This works on his plane
with
the Warp drive. But with the powerfin, you can pull the power off but
unless you slow the plane, the rpm doesn't change. The powerfin does
make a
great brake.
So is "prop slip" part of the formula in getting a prop to best fit
torque,
and power?
Randy
.
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of kurt
schrader
Sent: Tuesday, May 09, 2006 6:35 PM
Subject: Re: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: kurt schrader
<smokey_bear_40220@yahoo.com>
My flame suite on for another long one.....
---------------------------------
>Randy sez:
>
> >In short, if you want more thrust, all you have to
> >do is sacrifice top speed. Therefore, thrust is
> >irrelevant.
>-------------------------
>Mike G.
>N728KF
>If you want more thrust AND more top speed, you get
>an in-flight adjustable prop. You wouldn't drive
>your car in one gear all the time, why operate your
>airplane that way?
----------------------------
Good point Mike,
There is a misunderstanding on the list of thrust, HP
and torque. The whole purpose of the prop is to
convert power into thrust. Thrust is the most
relevant measure. It moves the plane.
But we are not talking about static thrust. You need
the best thrust at the speed you are flying for best
performance. Max static thrust is best at zero speed
only. Max takeoff thrust is best somewhere around 1/2
your takeoff speed. Max climb thrust is best at climb
speed. Max cruise thrust is best at.... ahhh you get
it.
A fixed pitch prop will give you its max thrust at
only one speed. You are compromising only in that you
pick the speed you want to have it perform best at.
At all other speeds, faster or slower, it will give
less then max thrust.
A variable or constant speed prop will still have one
best speed, but the curve will be flatter. It will
perform almost as well at all speeds as a fixed pitch
prop for its one speed.
Say a cruise fixed pitch gives efficiencies of:
50% in takeoff
75% in climb
85% in cruise
A climb prop might give:
65% in takeoff
85% in climb
80% in cruise
The variable prop might give:
75% in takeoff
82% in climb
83% in cruise
I have a friend who has a Champ product, his 3rd in 2
years. His 150 HP constant speed Champ would perform
equal to his 180 HP fixed pitch Champ, except around
one speed. That speed depended upon which fixed pitch
prop he installed. He might get better climb, but
equal cruise, or better cruise, but equal climb from
the extra 30 HP.
In his case, he used the prop that meant they cruised
equally, but the fixed pitch climbed better with the
30 more HP. If it had a constant speed prop, it would
have used the 30 extra HP for better performance all
across the speed range. His fixed pitch got off the
ground better, but burned more for the same cruise
speed.
Another way to say it is that the variable prop was
almost worth the 30 extra HP.
This is my problem with static thrust measurements.
It only gives you the measurement for the best prop at
no speed. How useful is that? I think that is what
Randy was saying.
Static thrust is only good when static. It is already
losing performance in the takeoff roll, but not so
badly as when at cruise speed. A cruise prop would be
poor but increasing performance in the takeoff roll,
and continue to get better all the way up to cruise.
The climb prop is of course in between, getting
better, then getting worse as speed increases.
As to HP and torque, if you are swinging a 2x4 around
with your engine, it will take HP and torque to do,
but produce no thrust. If you have a feathered prop,
it will take lots of HP and torque to swing and still
produce no thrust. The efficiency of the prop to
produce thrust is what makes the hp and torque
meaningful.
As a prop increases pitch, it moves more toward a
feathered prop in that the angle of lift of the prop
is more against torque and less forward producing
thrust. Lift of the prop is always about 90 degrees
to the blade. A pitch of say 20 degrees means that
some of the prop's lift is pulling air in a circle and
not just pushing it back. That takes HP.
When I flew the C-130, the pitch could be as high as
55 degrees in cruise. More than 1/2 the HP went to
spinning the air and less than 1/2 went to thrust.
Our props don't get that bad due to our less pitch.
But a heavily pitched prop may take the same HP/torque
as a finer pitched prop at higher RPM. The faster
turning, lower pitched prop will produce more thrust,
to a point. That point is determined by the most
efficient rpm for the prop compared to mach number,
and the most efficient rpm for the engine. Those 2
may not match.
A less efficient prop may take more HP or torque to
give the same performance, not more. A more efficient
prop will give more thrust with the same HP/torque.
HP and torque don't tell the whole story. They don't
give thrust, except as the prop allows.
So I am saying this. The prop that produces the most
thrust will be the one that has its best speed closest
to your engine's favorite RPM, but does it at the
speed you are flying. Also it has to be the most
aerodynamically efficient.
Max static thrust equals first gear only. Takeoff
props equal second gear. Climb props equal third
gear. Cruise props are overdrive. Variable props are
automatic trannys. That is Mike's point.
The actual performance of the plane will be determined
by just how much thrust it can produce today on this
fuel, at this temp, at this density altitude, with
this prop, at this speed, with these sparkplugs, at
this rpm and manifold setting..... You can measure
all that, or you can just measure thrust.
So thrust is really the key, but it has to be measured
now, at your speed and with all variables.
Static thrust is good for fans, not planes.
Thrust is what happens after all the variables are in
place. HP and torque are only what you are putting
into a prop, not what is coming out, which changes
with prop efficiency, speed, air density.....
So that is why I wanted a meter that simply measures
the thrust output on board at all speeds, altitudes,
settings, etc. It will tell you what performance you
are getting now, whatever now is.
And instead of HP, you can simply measure fuel flow if
the engine is tuned right. That is, if the fuel air
ratio is the same, fuel in equals power out.
That you can compare to whatever you want to change
and see if it made things better or worse. 10% more
thrust with the same fuel flow is 10% better no matter
how you got it. 10% more HP or 10% more torque might
just mean a 10% worse prop is giving equal thrust for
more gas.
Bottom line: Thrust = performance. Fuel flow =
energy and $ in to produce the thrust. The best prop
will be the one that gives you the most thrust per
fuel flow at the speed you want it.
A fixed pitch will peak at a given speed with a strong
curve. A variable prop will have a broader curve.
You have to pick the prop that peaks at the speed and
rpm that best matches your engine and most important
performance goal. This is critical for fixed pitch,
but less critical for variable.
Then you can compare one prop against another to see
which gives the most thrust at the same fuel flow.
Is this too much at once? Hope it can be understood.
You want thrust. Thrust moves the plane. We just
aren't use to measuring it directly. Fuel flow is
what we pay to get it and max fuel flow is how much
power is available under present conditions.
One day I will simplify this.....
Kurt S. S-5 flying and 1/2 done.
__________________________________________________
_________________________________________________________________
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Message 19
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| Subject: | Re: Thrust - Over Rated |
--> Kitfox-List message posted by: "John Anderson" <janderson412@hotmail.com>
And re stippage mentioned below, I have the skinny blades on my w/drive and
when the throttle is closed the RPM dropps off quite quickly and not a lot
of braking effect. But thrust wise it seems very good. John A.
From: "wingsdown" <wingsdown@comcast.net>
Subject: RE: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: "wingsdown" <wingsdown@comcast.net>
Excellent point John.
Rick
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of John
Anderson
Sent: Wednesday, May 10, 2006 4:21 PM
Subject: RE: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: "John Anderson"
--> <janderson412@hotmail.com>
Or you can turbo charge. This sort of does what a VPP does to a degree
in
that the RPM doesn't have to alter too much to increase power for t/off.
You
can set the prop at a courser angle and increase boost for t/off. John
A.
From: "Randy Daughenbaugh" <rjdaugh@rapidnet.com>
Subject: RE: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: "Randy Daughenbaugh"
<rjdaugh@rapidnet.com>
Thanks Kurt! As usual, another great post.
Maybe you can shed some light on my following comment.
You want to get the rpm's up on takeoff so you can use the power, but
you
want to have more pitch for more thrust at speed. You can approach this
with an in-flight adjustable prop, or you can get close by having a prop
that "slips" during take off, letting the engine rev up, but still has
enough pitch to make some thrust at speed.
I think this is a difference between the skinny blades of the warp drive
and
wide, high lift blades of the Powerfin. My CFI friend (16,000 hours)
was
impressed, but not favorably, on how my Powerfin prop was "connected" to
the
air. Engine rpm was not determined as much by throttle position as by
airspeed. In my plane, he was trying to teach me to set rpm to certain
number at different points in the approach. This works on his plane
with
the Warp drive. But with the powerfin, you can pull the power off but
unless you slow the plane, the rpm doesn't change. The powerfin does
make a
great brake.
So is "prop slip" part of the formula in getting a prop to best fit
torque,
and power?
Randy
.
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of kurt
schrader
Sent: Tuesday, May 09, 2006 6:35 PM
Subject: Re: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: kurt schrader
<smokey_bear_40220@yahoo.com>
My flame suite on for another long one.....
---------------------------------
>Randy sez:
>
> >In short, if you want more thrust, all you have to
> >do is sacrifice top speed. Therefore, thrust is
> >irrelevant.
>-------------------------
>Mike G.
>N728KF
>If you want more thrust AND more top speed, you get
>an in-flight adjustable prop. You wouldn't drive
>your car in one gear all the time, why operate your
>airplane that way?
----------------------------
Good point Mike,
There is a misunderstanding on the list of thrust, HP
and torque. The whole purpose of the prop is to
convert power into thrust. Thrust is the most
relevant measure. It moves the plane.
But we are not talking about static thrust. You need
the best thrust at the speed you are flying for best
performance. Max static thrust is best at zero speed
only. Max takeoff thrust is best somewhere around 1/2
your takeoff speed. Max climb thrust is best at climb
speed. Max cruise thrust is best at.... ahhh you get
it.
A fixed pitch prop will give you its max thrust at
only one speed. You are compromising only in that you
pick the speed you want to have it perform best at.
At all other speeds, faster or slower, it will give
less then max thrust.
A variable or constant speed prop will still have one
best speed, but the curve will be flatter. It will
perform almost as well at all speeds as a fixed pitch
prop for its one speed.
Say a cruise fixed pitch gives efficiencies of:
50% in takeoff
75% in climb
85% in cruise
A climb prop might give:
65% in takeoff
85% in climb
80% in cruise
The variable prop might give:
75% in takeoff
82% in climb
83% in cruise
I have a friend who has a Champ product, his 3rd in 2
years. His 150 HP constant speed Champ would perform
equal to his 180 HP fixed pitch Champ, except around
one speed. That speed depended upon which fixed pitch
prop he installed. He might get better climb, but
equal cruise, or better cruise, but equal climb from
the extra 30 HP.
In his case, he used the prop that meant they cruised
equally, but the fixed pitch climbed better with the
30 more HP. If it had a constant speed prop, it would
have used the 30 extra HP for better performance all
across the speed range. His fixed pitch got off the
ground better, but burned more for the same cruise
speed.
Another way to say it is that the variable prop was
almost worth the 30 extra HP.
This is my problem with static thrust measurements.
It only gives you the measurement for the best prop at
no speed. How useful is that? I think that is what
Randy was saying.
Static thrust is only good when static. It is already
losing performance in the takeoff roll, but not so
badly as when at cruise speed. A cruise prop would be
poor but increasing performance in the takeoff roll,
and continue to get better all the way up to cruise.
The climb prop is of course in between, getting
better, then getting worse as speed increases.
As to HP and torque, if you are swinging a 2x4 around
with your engine, it will take HP and torque to do,
but produce no thrust. If you have a feathered prop,
it will take lots of HP and torque to swing and still
produce no thrust. The efficiency of the prop to
produce thrust is what makes the hp and torque
meaningful.
As a prop increases pitch, it moves more toward a
feathered prop in that the angle of lift of the prop
is more against torque and less forward producing
thrust. Lift of the prop is always about 90 degrees
to the blade. A pitch of say 20 degrees means that
some of the prop's lift is pulling air in a circle and
not just pushing it back. That takes HP.
When I flew the C-130, the pitch could be as high as
55 degrees in cruise. More than 1/2 the HP went to
spinning the air and less than 1/2 went to thrust.
Our props don't get that bad due to our less pitch.
But a heavily pitched prop may take the same HP/torque
as a finer pitched prop at higher RPM. The faster
turning, lower pitched prop will produce more thrust,
to a point. That point is determined by the most
efficient rpm for the prop compared to mach number,
and the most efficient rpm for the engine. Those 2
may not match.
A less efficient prop may take more HP or torque to
give the same performance, not more. A more efficient
prop will give more thrust with the same HP/torque.
HP and torque don't tell the whole story. They don't
give thrust, except as the prop allows.
So I am saying this. The prop that produces the most
thrust will be the one that has its best speed closest
to your engine's favorite RPM, but does it at the
speed you are flying. Also it has to be the most
aerodynamically efficient.
Max static thrust equals first gear only. Takeoff
props equal second gear. Climb props equal third
gear. Cruise props are overdrive. Variable props are
automatic trannys. That is Mike's point.
The actual performance of the plane will be determined
by just how much thrust it can produce today on this
fuel, at this temp, at this density altitude, with
this prop, at this speed, with these sparkplugs, at
this rpm and manifold setting..... You can measure
all that, or you can just measure thrust.
So thrust is really the key, but it has to be measured
now, at your speed and with all variables.
Static thrust is good for fans, not planes.
Thrust is what happens after all the variables are in
place. HP and torque are only what you are putting
into a prop, not what is coming out, which changes
with prop efficiency, speed, air density.....
So that is why I wanted a meter that simply measures
the thrust output on board at all speeds, altitudes,
settings, etc. It will tell you what performance you
are getting now, whatever now is.
And instead of HP, you can simply measure fuel flow if
the engine is tuned right. That is, if the fuel air
ratio is the same, fuel in equals power out.
That you can compare to whatever you want to change
and see if it made things better or worse. 10% more
thrust with the same fuel flow is 10% better no matter
how you got it. 10% more HP or 10% more torque might
just mean a 10% worse prop is giving equal thrust for
more gas.
Bottom line: Thrust = performance. Fuel flow =
energy and $ in to produce the thrust. The best prop
will be the one that gives you the most thrust per
fuel flow at the speed you want it.
A fixed pitch will peak at a given speed with a strong
curve. A variable prop will have a broader curve.
You have to pick the prop that peaks at the speed and
rpm that best matches your engine and most important
performance goal. This is critical for fixed pitch,
but less critical for variable.
Then you can compare one prop against another to see
which gives the most thrust at the same fuel flow.
Is this too much at once? Hope it can be understood.
You want thrust. Thrust moves the plane. We just
aren't use to measuring it directly. Fuel flow is
what we pay to get it and max fuel flow is how much
power is available under present conditions.
One day I will simplify this.....
Kurt S. S-5 flying and 1/2 done.
__________________________________________________
_________________________________________________________________
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FREE!
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Message 20
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|
| Subject: | Re: Thrust - Over Rated |
--> Kitfox-List message posted by: "wingsdown" <wingsdown@comcast.net>
If anyone else has the CAP 140, get some altitude pull power reverse
pitch , apply power. If you have never been forced to lean forward in
flight it's a trip...watch you air speed, it bleeds off quick. Also
great for that unexpected down wind short field landing. Don't know how
I know that. You can do some pretty fast base to finals and put her on
the numbers, takes some nerve though, the pitch doesn't return that fast
should you need forward power. I use to love to back up from the fuel
pumps, the looks you get are just amazing.
Rick
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of John
Anderson
Sent: Wednesday, May 10, 2006 7:15 PM
Subject: RE: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: "John Anderson"
--> <janderson412@hotmail.com>
Yes Rick, I'm sure that's why I'm getting such a good result performance
wise. John
From: "wingsdown" <wingsdown@comcast.net>
Subject: RE: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: "wingsdown" <wingsdown@comcast.net>
Excellent point John.
Rick
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of John
Anderson
Sent: Wednesday, May 10, 2006 4:21 PM
Subject: RE: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: "John Anderson"
--> <janderson412@hotmail.com>
Or you can turbo charge. This sort of does what a VPP does to a degree
in that the RPM doesn't have to alter too much to increase power for
t/off. You can set the prop at a courser angle and increase boost for
t/off. John A.
From: "Randy Daughenbaugh" <rjdaugh@rapidnet.com>
Subject: RE: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: "Randy Daughenbaugh"
<rjdaugh@rapidnet.com>
Thanks Kurt! As usual, another great post.
Maybe you can shed some light on my following comment.
You want to get the rpm's up on takeoff so you can use the power, but
you want to have more pitch for more thrust at speed. You can approach
this with an in-flight adjustable prop, or you can get close by having a
prop that "slips" during take off, letting the engine rev up, but still
has enough pitch to make some thrust at speed.
I think this is a difference between the skinny blades of the warp drive
and wide, high lift blades of the Powerfin. My CFI friend (16,000
hours) was impressed, but not favorably, on how my Powerfin prop was
"connected" to the air. Engine rpm was not determined as much by
throttle position as by airspeed. In my plane, he was trying to teach
me to set rpm to certain number at different points in the approach.
This works on his plane with the Warp drive. But with the powerfin, you
can pull the power off but unless you slow the plane, the rpm doesn't
change. The powerfin does make a great brake.
So is "prop slip" part of the formula in getting a prop to best fit
torque, and power?
Randy
.
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of kurt
schrader
Sent: Tuesday, May 09, 2006 6:35 PM
Subject: Re: Kitfox-List: Re: Thrust - Over Rated
--> Kitfox-List message posted by: kurt schrader
<smokey_bear_40220@yahoo.com>
My flame suite on for another long one.....
---------------------------------
>Randy sez:
>
> >In short, if you want more thrust, all you have to
> >do is sacrifice top speed. Therefore, thrust is
> >irrelevant.
>-------------------------
>Mike G.
>N728KF
>If you want more thrust AND more top speed, you get
>an in-flight adjustable prop. You wouldn't drive
>your car in one gear all the time, why operate your
>airplane that way?
----------------------------
Good point Mike,
There is a misunderstanding on the list of thrust, HP
and torque. The whole purpose of the prop is to
convert power into thrust. Thrust is the most
relevant measure. It moves the plane.
But we are not talking about static thrust. You need
the best thrust at the speed you are flying for best performance. Max
static thrust is best at zero speed only. Max takeoff thrust is best
somewhere around 1/2 your takeoff speed. Max climb thrust is best at
climb speed. Max cruise thrust is best at.... ahhh you get it.
A fixed pitch prop will give you its max thrust at
only one speed. You are compromising only in that you
pick the speed you want to have it perform best at.
At all other speeds, faster or slower, it will give
less then max thrust.
A variable or constant speed prop will still have one
best speed, but the curve will be flatter. It will
perform almost as well at all speeds as a fixed pitch
prop for its one speed.
Say a cruise fixed pitch gives efficiencies of:
50% in takeoff
75% in climb
85% in cruise
A climb prop might give:
65% in takeoff
85% in climb
80% in cruise
The variable prop might give:
75% in takeoff
82% in climb
83% in cruise
I have a friend who has a Champ product, his 3rd in 2
years. His 150 HP constant speed Champ would perform
equal to his 180 HP fixed pitch Champ, except around
one speed. That speed depended upon which fixed pitch
prop he installed. He might get better climb, but
equal cruise, or better cruise, but equal climb from
the extra 30 HP.
In his case, he used the prop that meant they cruised
equally, but the fixed pitch climbed better with the
30 more HP. If it had a constant speed prop, it would
have used the 30 extra HP for better performance all
across the speed range. His fixed pitch got off the
ground better, but burned more for the same cruise
speed.
Another way to say it is that the variable prop was
almost worth the 30 extra HP.
This is my problem with static thrust measurements.
It only gives you the measurement for the best prop at
no speed. How useful is that? I think that is what
Randy was saying.
Static thrust is only good when static. It is already
losing performance in the takeoff roll, but not so
badly as when at cruise speed. A cruise prop would be
poor but increasing performance in the takeoff roll,
and continue to get better all the way up to cruise.
The climb prop is of course in between, getting
better, then getting worse as speed increases.
As to HP and torque, if you are swinging a 2x4 around
with your engine, it will take HP and torque to do,
but produce no thrust. If you have a feathered prop,
it will take lots of HP and torque to swing and still
produce no thrust. The efficiency of the prop to
produce thrust is what makes the hp and torque
meaningful.
As a prop increases pitch, it moves more toward a
feathered prop in that the angle of lift of the prop
is more against torque and less forward producing
thrust. Lift of the prop is always about 90 degrees
to the blade. A pitch of say 20 degrees means that
some of the prop's lift is pulling air in a circle and
not just pushing it back. That takes HP.
When I flew the C-130, the pitch could be as high as
55 degrees in cruise. More than 1/2 the HP went to
spinning the air and less than 1/2 went to thrust.
Our props don't get that bad due to our less pitch.
But a heavily pitched prop may take the same HP/torque
as a finer pitched prop at higher RPM. The faster
turning, lower pitched prop will produce more thrust,
to a point. That point is determined by the most
efficient rpm for the prop compared to mach number,
and the most efficient rpm for the engine. Those 2
may not match.
A less efficient prop may take more HP or torque to
give the same performance, not more. A more efficient
prop will give more thrust with the same HP/torque.
HP and torque don't tell the whole story. They don't
give thrust, except as the prop allows.
So I am saying this. The prop that produces the most
thrust will be the one that has its best speed closest
to your engine's favorite RPM, but does it at the
speed you are flying. Also it has to be the most aerodynamically
efficient.
Max static thrust equals first gear only. Takeoff
props equal second gear. Climb props equal third
gear. Cruise props are overdrive. Variable props are automatic
trannys. That is Mike's point.
The actual performance of the plane will be determined
by just how much thrust it can produce today on this
fuel, at this temp, at this density altitude, with
this prop, at this speed, with these sparkplugs, at
this rpm and manifold setting..... You can measure
all that, or you can just measure thrust.
So thrust is really the key, but it has to be measured
now, at your speed and with all variables.
Static thrust is good for fans, not planes.
Thrust is what happens after all the variables are in
place. HP and torque are only what you are putting
into a prop, not what is coming out, which changes
with prop efficiency, speed, air density.....
So that is why I wanted a meter that simply measures
the thrust output on board at all speeds, altitudes,
settings, etc. It will tell you what performance you
are getting now, whatever now is.
And instead of HP, you can simply measure fuel flow if
the engine is tuned right. That is, if the fuel air
ratio is the same, fuel in equals power out.
That you can compare to whatever you want to change
and see if it made things better or worse. 10% more
thrust with the same fuel flow is 10% better no matter
how you got it. 10% more HP or 10% more torque might
just mean a 10% worse prop is giving equal thrust for
more gas.
Bottom line: Thrust = performance. Fuel flow =
energy and $ in to produce the thrust. The best prop
will be the one that gives you the most thrust per
fuel flow at the speed you want it.
A fixed pitch will peak at a given speed with a strong
curve. A variable prop will have a broader curve.
You have to pick the prop that peaks at the speed and
rpm that best matches your engine and most important performance goal.
This is critical for fixed pitch, but less critical for variable.
Then you can compare one prop against another to see
which gives the most thrust at the same fuel flow.
Is this too much at once? Hope it can be understood.
You want thrust. Thrust moves the plane. We just
aren't use to measuring it directly. Fuel flow is
what we pay to get it and max fuel flow is how much
power is available under present conditions.
One day I will simplify this.....
Kurt S. S-5 flying and 1/2 done.
__________________________________________________
_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today - it's
FREE! http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/
_________________________________________________________________
Discover fun and games at @ http://xtramsn.co.nz/kids
Message 21
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|
| Subject: | Re: Hydraulic brakes |
--> Kitfox-List message posted by: Mike Ford <fordm2003@yahoo.com>
How many other people out there have Cleveland brakes? Do you like them? I have
just recently broken the left control arm off of my model 4's rudder pedal.
About two weeks before that, I was attempting to fix a small weep at the caliper
(weeping at the fitting). After I got the pedals bled, I'd test them out. I've
always had a hard time breaking the tail wheel free when spinning to the right.
I would also have a hard time getting the plane to go straight after a
successful spin to the left (which is why I looked into the brake fluid weep in
the first place)
When testing the brakes, I'd use them in a heavy manner trying to get them to hold
enough to spin the plane, but I ended up fatiguing the rudder pedal assembly
instead.
I've tried to the weep about 7 times, even took it to an A&P, but all the fussing
has ended up making the leak worse. I would now be happy with the leak I had
before trouble shooting.
I'm currently having my pedals fixed and reinforced.
Are Cleveland brakes a world of difference?
I've also read up on the brake it procedure for the Matco brakes. I have not tried
it yet. I was told that they look to be worn in correctly.
Mike Ford
M4 speedster 912
Rexster <runwayrex@juno.com> wrote: --> Kitfox-List message posted by: "Rexster"
Those probably are Matco brakes. I changed from Matco to Cleveland and w=
as very impressed with the difference. With the Matco brakes, some peopl=
e were breaking rudder pedals trying to hold the plane during run-ups. W=
ith the Clevelands, rudder pedal forces were greatly reduced. That's my =
experience.
Rex Phelps/ Michigan
-- Malcolmbru@aol.com wrote:
--> Kitfox-List message posted by: Malcolmbru@aol.com
I have a KF2 finished in 1999 and can find nothing in my records on the=
=
brakes. They are hydraulic and look like matko but they have no writ=
ing at all =
on them. They are all aluminum and the peddles look just like the on=
es in =
the builders manual as do the axis one caliper is sticking , the roto=
r =
gets real hot and the other is leaking rite through the wall. like a po=
ris spot =
in the aluminum What to do? =
---------------------------------
Yahoo! Mail goes everywhere you do. Get it on your phone.
Message 22
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|
| Subject: | Re: Bing 54 Choke adjustment |
--> Kitfox-List message posted by: Guy Buchanan <bnn@nethere.com>
At 07:12 AM 5/7/2006, you wrote:
> Now would someone tell me the proper way to adjust the cables on the
>new chokes?
I adjusted mine so there was some play in the cable housing at the carb. In
other words: I pulled the black boot at the carb end of the choke cable
well up the cable. I installed the entire choke system. I then backed out
the adjuster until there was about .03" vertical play in the cable housing
at the carb. I then tightened the adjusting nut and checked the play again.
I then pulled the boot down over the adjusting nut and tie wrapped the top
and bottom of the boot so the cable housing couldn't pull up.
Guy Buchanan
K-IV 1200 / 582 / 99.9% done, thanks mostly to Bob Ducar.
Message 23
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| Subject: | Re: Hydraulic brakes |
--> Kitfox-List message posted by: kurt schrader <smokey_bear_40220@yahoo.com>
Hi Mike,
If you read any airplane for sale papers, they always
proudly say they have Clevelands when they do. It is
a selling point because they work and the Matco's are
paper weights in comparison.
Nothing is cheap, but replacing the brakes might keep
you from bending the plane in the future.
Mine work and hold the plane on runup with maybe 35%
of the force I could put on them. That is with a 140
HP engine, but run up at about 40% power. I have run
it up harder, but I'd worry about nosing over with
100% power before the brakes would slide. It doesn't
seem to need any more brake force, even at higher
power.
kurt S. S-5/NSI turbo
--- Mike Ford <fordm2003@yahoo.com> wrote:
..............
> Are Cleveland brakes a world of difference?
>
> Mike Ford
> M4 speedster 912
__________________________________________________
Message 24
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| Subject: | Re: Thrust - Over Rated |
--> Kitfox-List message posted by: kurt schrader <smokey_bear_40220@yahoo.com>
Not me Rick ;-)
I know Lance did this with another, bigger plane and
had it down at something like 165 degrees and full
reverse! It works, but frankly, I am a chicken. :-(
Maybe in a few more years and 100's more Fox hours....
kurt S.
--- wingsdown <wingsdown@comcast.net> wrote:
> If anyone else has the CAP 140, get some altitude
> pull power reverse
> pitch , apply power. If you have never been forced
> to lean forward in
> flight it's a trip...watch you air speed, it bleeds
> off quick. Also
> great for that unexpected down wind short field
> landing. Don't know how
> I know that. You can do some pretty fast base to
> finals and put her on
> the numbers, takes some nerve though, the pitch
> doesn't return that fast
> should you need forward power. I use to love to
> back up from the fuel
> pumps, the looks you get are just amazing.
>
> Rick
__________________________________________________
Message 25
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| Subject: | Re: Hydraulic brakes |
--> Kitfox-List message posted by: "Lowell Fitt" <lcfitt@sbcglobal.net>
Mike, this is from the old days, but one oldtimer I respected quite a bit
when he was on the list cautioned about too much braking on a tail dragger.
I have the matcos and yes it takes a bit of pressure to hold the airplane
during run-up, but I can easily lift the tail wheel with heavy breaking on
landing. The rudder pedal failures were an issue and the reinforcement was
ADd several years ago. As to the assymetry in braking, obviously that needs
addressing.
Lowell
----- Original Message -----
From: "Mike Ford" <fordm2003@yahoo.com>
Sent: Wednesday, May 10, 2006 8:04 PM
Subject: Re: Kitfox-List: Hydraulic brakes
> --> Kitfox-List message posted by: Mike Ford <fordm2003@yahoo.com>
>
> How many other people out there have Cleveland brakes? Do you like them?
> I have just recently broken the left control arm off of my model 4's
> rudder pedal.
>
> About two weeks before that, I was attempting to fix a small weep at the
> caliper (weeping at the fitting). After I got the pedals bled, I'd test
> them out. I've always had a hard time breaking the tail wheel free when
> spinning to the right. I would also have a hard time getting the plane to
> go straight after a successful spin to the left (which is why I looked
> into the brake fluid weep in the first place)
>
> When testing the brakes, I'd use them in a heavy manner trying to get them
> to hold enough to spin the plane, but I ended up fatiguing the rudder
> pedal assembly instead.
>
> I've tried to the weep about 7 times, even took it to an A&P, but all the
> fussing has ended up making the leak worse. I would now be happy with the
> leak I had before trouble shooting.
>
> I'm currently having my pedals fixed and reinforced.
>
> Are Cleveland brakes a world of difference?
>
> I've also read up on the brake it procedure for the Matco brakes. I have
> not tried it yet. I was told that they look to be worn in correctly.
>
>
> Mike Ford
> M4 speedster 912
>
>
> Rexster <runwayrex@juno.com> wrote: --> Kitfox-List message posted by:
> "Rexster"
>
> Those probably are Matco brakes. I changed from Matco to Cleveland and w=
> as very impressed with the difference. With the Matco brakes, some peopl=
> e were breaking rudder pedals trying to hold the plane during run-ups. W=
> ith the Clevelands, rudder pedal forces were greatly reduced. That's my =
> experience.
> Rex Phelps/ Michigan
>
>
> -- Malcolmbru@aol.com wrote:
> --> Kitfox-List message posted by: Malcolmbru@aol.com
>
> I have a KF2 finished in 1999 and can find nothing in my records on the=
> =
>
> brakes. They are hydraulic and look like matko but they have no writ=
> ing at all =
>
> on them. They are all aluminum and the peddles look just like the on=
> es in =
>
> the builders manual as do the axis one caliper is sticking , the roto=
> r =
>
> gets real hot and the other is leaking rite through the wall. like a po=
> ris spot =
>
> in the aluminum What to do? =
>
>
> ---------------------------------
> Yahoo! Mail goes everywhere you do. Get it on your phone.
>
>
>
Message 26
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| Subject: | Re: Thrust - Over Rated |
--> Kitfox-List message posted by: kurt schrader <smokey_bear_40220@yahoo.com>
You guys are too fast for me to get back to you...
Simple becomes complex, or is it just me lately? You
are right. I don't have time to shorten this!
Yes, there is a lot more to prop selection. The
number of blades and cord of the blade add up to what
is called solidity. I don't remember all of the prop
facts without researching it again, but here are a few
things:
The prop is thought of as a screw and the plane of
rotation the prop disk. So if the screw were to fill
just one full revolution with one blade, it would be
100% solid. That is, no space you could poke 90
degrees thru the disk without hitting blade.
A wide cord blade fills more of the disk than a narrow
cord. Two blades more than one, three more than two,
etc. More solidity generally = less slip. Slip is
greater at low speeds.
The "perfect" prop would theoritically have one (1)
infinately long and infinately thin blade with a
counter weight. Very little solidity, but what an
aspect ratio! Spin this as slow as possible to just
barely create thrust and that is as close to 100%
efficient as you can get. No tip losses or friction
to measure, etc. Forget ground clearance and gearing
down friction losses though! ;-)
There have been very few one blade props! Tried?
Yes, but very few. None infinate....
There have been a few 3 blade props that outperformed
the 2 blade props they replaced, but I would fault the
2 bladed for not being as efficient as it could have
been.
Other considerations are ground clearance requires
more solidity to absorbe the HP without more length.
Wider blades and more blades absorbe more HP when
length is restricted. If you add HP, you probably
will need more solidity by adding another blade, or at
least wider blades.
Engine vibration may favor 3 blades. Even numbers are
better structurally, but odd are better for vibration
absorbtion.
Quiet operation comes from more blades going slower.
Efficiency comes from running the tips around mach .80
or so, depending on the airfoil and tip design. A
slanted tip like a swept back wing, seems to help.
The faster the tips can go without creating a lot of
drag, the closer the rest of the blade comes to its
best speed.
The more leading edges you have, the more air to
divide and the more shockwave drag. Thus fewer blades
win here.
Longer blades blow more air around and outside of the
plane. The plane fills less of the slipstream, so it
slows less of it down.
Extending the prop even a few inches away from the
cowl reduces drag measurably. See how LoPresti opens
up the airflow behind the prop and around the cowl on
all his mods.
Direct drive higher rpm engines require shorter blades
to avoid tips reaching mach one, which cause a lot of
drag and noise. But shorter blades are less
efficient.
Noise = waste. There is a direct relationship here.
Check your kids stereo. Watts for decibels. Bell
Helicopter actually figured how much HP it took to do
Wap Wap... Then they changed the tips. Noise does
not = thrust or lift.
Twist, airfoil shape, taper, tip shape, flex, material
(wood, metal, composit, combinations)
Props aren't as simple as they look and only good
testing will provide a good design or comparison
between designs. It is still quite a bit of art since
there are so many factors to compromise on.
So where does this actually get us?
When I lived in KY, I had a hill to climb up to the
runway almost right out of the hangar. One day I was
on that hill and trying to get it going because I was
about to stop. I added pitch, then power and rolled
backwards down the hill. More power = less thrust?
I had stalled the prop! I was just slinging air.
More RPM and less pitch and it clawed right up the
hill as it should.
In this case slip was a real bad deal. I was
surprised at how much power I had put in it (stalled)
and it felt like nothing. It seemed like at full
power I could have pushed the plane backwards by hand.
WOW! I learned from that. RPM, then pitch. Note:
That is with narrow cord Warp blades.
Those little racers that are trying to get as much as
possible out of the same size little engine use props
that are way over-pitched for takeoff. I was told
they were stalled at the beginning of the roll, but
now I don't know. Isn't someone here a racer who can
tell us? Maybe they are still light enough to get
going stalled then the prop grabs when it unstalls on
the roll.
So Randy, a little bit backwards. You should get less
slip with less pitch and more RPM on the same prop,
stalled or not but certainly a lot of slip stalled.
You are slipping more at higher pitch and low rpm.
But you're correct with the solitity of the blades, I
think. Wider cord or more blades will work better
slow, and narrow blades will grip better at speed, or
at least waste less. There is a lot of slip at low
speed and solidity will help here. Going fast though,
the high aspect ratio thin blades win.
Whew....
Kurt S.
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Message 27
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| Subject: | Re: Thrust - Over Rated |
--> Kitfox-List message posted by: kurt schrader <smokey_bear_40220@yahoo.com>
I am still trying to find the best pitch for my CAP
prop for landing. Too little and go-around is just a
noisy landing. Too much and the rpm decreases with
speed until the engine is near dead on rollout. A
touch of throttle to keep RPM up and I float forever.
The difference in pitch is still hard to find for me.
I need to find a measure to make it simple. This is
where the fixed pitch prop is easier, unless I had a
constant speed prop. ;-)
I don't have the pitch meter, but wish I had something
for consistancy. Any experienced CAP drivers have a
solution?
Kurt S. S-5/NSI turbo + CAP
--- John Anderson <janderson412@hotmail.com> wrote:
> And re slippage mentioned below, I have the skinny
> blades on my w/drive and
> when the throttle is closed the RPM dropps off quite
> quickly and not a lot
> of braking effect. But thrust wise it seems very
> good. John A.
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Message 28
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| Subject: | Re: Thrust - Over Rated |
--> Kitfox-List message posted by: kurt schrader <smokey_bear_40220@yahoo.com>
Sounds like it is right in there John.
My goal is 100 knots cruise at less than 6 gph. Not
as slippery as the IV's and earlier, but comfortable
to sit in.
Right now I am more comfortable at 85 knots (97 mph
for those who use it) and 5 gph.
I need more drag reduction devices, but I decided to
test each as I add them to see what really does what.
So my plane started out a drag bucket and is improving
with each add on, so far. My top speed used to be 95
knots and you could feel it fight!
Another problem is that my engine goes lean, even at
full rich, around the 4000 rpm area. No problem
higher or lower, but I don't like the EGT's from 3600
to 4300. I cruise at 3200 rpm and it is quiet. :-)
Kurt S.
--- John Anderson <janderson412@hotmail.com> wrote:
> Early days on fuel flow but seems to be around 15
> litres per hour and I
> don't have a flow meter. 4500 on t/o, more there if
> I want with prop setting
> but that's what I use, climb 1200fpm. 97kts at 4300.
> Just me in it tho at this early stage.
John
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Message 29
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| Subject: | Re: Thrust...Overrated? |
--> Kitfox-List message posted by: kurt schrader <smokey_bear_40220@yahoo.com>
Hi Clem,
I would really like to see more prop testing on our
planes too. There are a lot of considerations with
the different engines and Fox models, but we have so
many opportunities.
What engine is he running the wood prop on the Rans?
Maybe someone with the same engine here would benefit.
Generally speaking, the 2 blade should be the best
compromise.
Someone who really knows what they are doing with prop
aerodynamics would probably make the best blades out
of composit, due to the ability to form it better.
Kurt S.
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