Today's Message Index:
----------------------
1. 12:38 AM - Re: Balance Master (Bill Berle)
2. 06:31 AM - Re: Balance Master (Jack Hart)
3. 06:34 AM - Re: Balance Master (Jack Hart)
4. 06:40 AM - Re: Balance Master (Jack Hart)
5. 06:57 AM - Re: Balance Master (Jack Hart)
6. 07:28 AM - Re: Balance Master (Jack Hart)
7. 08:29 AM - Re: Balance Master (Jack Hart)
8. 10:02 AM - Re: Balance Master (Jack Hart)
9. 11:00 AM - Re: Balance Master (Richard Pike)
10. 11:21 AM - Re: Re: Balance Master (John Hauck)
11. 11:46 AM - Re: Re: Balance Master (Charlie England)
12. 12:50 PM - Re: Re: Balance Master (Bill Berle)
13. 01:04 PM - Re: Firestar 2 / HKS engine progress (Bill Berle)
14. 04:50 PM - Re: Balance Master (Richard Pike)
15. 08:42 PM - Re: Re: Balance Master (Bill Berle)
Message 1
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Subject: | Re: Balance Master |
The Balance Master guy came to our EAA chapter meeting and made a presentation.
Very impressive. He had a small electric motor driving an un-balanced disc with
a weight mounted off center. It shook itself half to death on the table. He
installed the balance Master device and the thing ran smoothly. We all looked
at it to see if it was some sort of scam, or that he had "rigged" the demonstration,
but it looked 100% legit to all of us.
Bill Berle
www.ezflaphandle.com - safety & performance upgrade for light aircraft
www.grantstar.net - winning proposals for non-profit and for-profit entities
--------------------------------------------
On Sun, 4/22/18, Richard Pike <thegreybaron@charter.net> wrote:
Subject: Kolb-List: Balance Master
To: kolb-list@matronics.com
Date: Sunday, April 22, 2018, 3:18 PM
Pike" <thegreybaron@charter.net>
I have seen these advertised for years,
no personal experience.
http://balancemasters.com/aircraft.html
The engine/gearbox/prop on the FF is a
Rotax 277, B-box (2.58:1) and two blade 62" Ivo, and is very
smooth over 5200 rpm but terrible between 5100-4000.
Performance is excellent other than the vibration. I am
thinking harmonics, but who knows???
Wondering if the Balance Master would
be worth trying, but before I spend the $, would like to
hear from somebody who has actually tried one.
Thanks.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Forgiving is tough, being forgiven is
wonderful, and God's grace really is amazing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=479482#479482
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Message 2
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Richard,
Hold on a day. I have one I will send to you after I find it.
Jack B. Hart FF004
Winchester, IN
----------------------------------------
From: "Richard Pike" <thegreybaron@charter.net>
Sent: Sunday, April 22, 2018 6:20 PM
Subject: Kolb-List: Balance Master
I have seen these advertised for years, no personal experience.
http://balancemasters.com/aircraft.html
The engine/gearbox/prop on the FF is a Rotax 277, B-box (2.58:1) and two
blade 62" Ivo, and is very smooth over 5200 rpm but terrible between
5100-4000. Performance is excellent other than the vibration. I am thinking
harmonics, but who knows???
Wondering if the Balance Master would be worth trying, but before I spend
the $, would like to hear from somebody who has actually tried one.
Thanks.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Message 3
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Richard,
Hold on a day. I have one I will send to you after I find it.
Jack B. Hart FF004
Winchester, IN
----------------------------------------
From: "Richard Pike" <thegreybaron@charter.net>
Sent: Sunday, April 22, 2018 6:20 PM
Subject: Kolb-List: Balance Master
I have seen these advertised for years, no personal experience.
http://balancemasters.com/aircraft.html
The engine/gearbox/prop on the FF is a Rotax 277, B-box (2.58:1) and two
blade 62" Ivo, and is very smooth over 5200 rpm but terrible between
5100-4000. Performance is excellent other than the vibration. I am thinking
harmonics, but who knows???
Wondering if the Balance Master would be worth trying, but before I spend
the $, would like to hear from somebody who has actually tried one.
Thanks.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Message 4
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Richard,
Hold on a day. I have one I will send to you after I find it.
Jack B. Hart FF004
Winchester, IN
----------------------------------------
From: "Richard Pike" <thegreybaron@charter.net>
Sent: Sunday, April 22, 2018 6:20 PM
Subject: Kolb-List: Balance Master
I have seen these advertised for years, no personal experience.
http://balancemasters.com/aircraft.html
The engine/gearbox/prop on the FF is a Rotax 277, B-box (2.58:1) and two
blade 62" Ivo, and is very smooth over 5200 rpm but terrible between
5100-4000. Performance is excellent other than the vibration. I am thinking
harmonics, but who knows???
Wondering if the Balance Master would be worth trying, but before I spend
the $, would like to hear from somebody who has actually tried one.
Thanks.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Message 5
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Richard,
Hold on a day. I have one I will send to you after I find it.
Jack B. Hart FF004
Winchester, IN
----------------------------------------
From: "Richard Pike" <thegreybaron@charter.net>
Sent: Sunday, April 22, 2018 6:20 PM
Subject: Kolb-List: Balance Master
I have seen these advertised for years, no personal experience.
http://balancemasters.com/aircraft.html
The engine/gearbox/prop on the FF is a Rotax 277, B-box (2.58:1) and two
blade 62" Ivo, and is very smooth over 5200 rpm but terrible between
5100-4000. Performance is excellent other than the vibration. I am thinking
harmonics, but who knows???
Wondering if the Balance Master would be worth trying, but before I spend
the $, would like to hear from somebody who has actually tried one.
Thanks.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Message 6
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Richard,
Hold on a day. I have one I will send to you after I find it.
Jack B. Hart FF004
Winchester, IN
----------------------------------------
From: "Richard Pike" <thegreybaron@charter.net>
Sent: Sunday, April 22, 2018 6:20 PM
Subject: Kolb-List: Balance Master
I have seen these advertised for years, no personal experience.
http://balancemasters.com/aircraft.html
The engine/gearbox/prop on the FF is a Rotax 277, B-box (2.58:1) and two
blade 62" Ivo, and is very smooth over 5200 rpm but terrible between
5100-4000. Performance is excellent other than the vibration. I am thinking
harmonics, but who knows???
Wondering if the Balance Master would be worth trying, but before I spend
the $, would like to hear from somebody who has actually tried one.
Thanks.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Message 7
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Richard,
Hold on a day. I have one I will send to you after I find it.
Jack B. Hart FF004
Winchester, IN
----------------------------------------
From: "Richard Pike" <thegreybaron@charter.net>
Sent: Sunday, April 22, 2018 6:20 PM
Subject: Kolb-List: Balance Master
I have seen these advertised for years, no personal experience.
http://balancemasters.com/aircraft.html
The engine/gearbox/prop on the FF is a Rotax 277, B-box (2.58:1) and two
blade 62" Ivo, and is very smooth over 5200 rpm but terrible between
5100-4000. Performance is excellent other than the vibration. I am thinking
harmonics, but who knows???
Wondering if the Balance Master would be worth trying, but before I spend
the $, would like to hear from somebody who has actually tried one.
Thanks.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Message 8
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Richard,
Hold on a day. I have one I will send to you after I find it.
Jack B. Hart FF004
Winchester, IN
----------------------------------------
From: "Richard Pike" <thegreybaron@charter.net>
Sent: Sunday, April 22, 2018 6:20 PM
Subject: Kolb-List: Balance Master
I have seen these advertised for years, no personal experience.
http://balancemasters.com/aircraft.html
The engine/gearbox/prop on the FF is a Rotax 277, B-box (2.58:1) and two
blade 62" Ivo, and is very smooth over 5200 rpm but terrible between
5100-4000. Performance is excellent other than the vibration. I am thinking
harmonics, but who knows???
Wondering if the Balance Master would be worth trying, but before I spend
the $, would like to hear from somebody who has actually tried one.
Thanks.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Message 9
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Subject: | Re: Balance Master |
Jack Hart: What a prince! Thank you, can't wait to try it out and see how it does.
John Hauck: you are correct, I am sure that the Austrian gnomes at Gunskirchen
tuned the 277 for optimum power between 6250 and 6500, and I am sure it would
happily churn away at that speed all day. However, while 6250 - 6500 rpm is where
the engine makes its rated power, that does not necessitate the engine having
to be consistently operated at that rpm.
Here is a very good website of tutorials by the Australian light aircraft people - https://www.recreationalflying.com/tutorials/index.html
and from their page on "Engines and Propellers",
"Although aero-engines can quite happily operate continually at their rated power,
doing so is not good practice. It is uneconomical in terms of fuel efficiency,
but more importantly it may shorten engine life, if engine operating temperatures
and pressures are exceeded. Normally the maximum and optimum power
setting for continuous cruise operation is 75% of rated power."
Then they deal specifically with the 2-stroke; "Two-strokes don't have very good
volumetric efficiency, and the engine is generally efficient only in the upper
30% of its rpm and throttle opening range. In fact, ultralight two-strokes
tend to run very roughly at speeds below 2500 rpm and achieve their rated power
at rotational speeds in the 5500 to 6500 rpm range. The three most common two-strokes
are two-cylinder models with individual cylinder displacements around
250 cc; they achieve their rated power at 6500 rpm and 75% power at around 5300
rpm."
Something else to consider is that running an engine slower than its rated power
does not lug it. Once again from the recreationalflying.com tutorial page: "the
power delivered by a propeller varies in accordance with rpm cubed (if everything
else is kept constant)" Therefore, as rpm is decreased from the engine/propeller
maximum attainable rpm, the load reduction on the engine decreases
exponentially. (don't know the right technical term for a decrease cubed, but
you get the idea)
Back when I was flying a Maxair Hummer with a Rotax 277, it spent most of its time
around 54-5500 rpm. The 582 on my MKIII spends most of its time around 54-5500
rpm solo, 56-5700 rpm when I have a passenger. When I am in a hurry, it runs
at 6200 rpm and sucks gas like it was free.
The 277 on the Firefly is still breaking in, but right now it appears that the
sweet spot is going to be around 5500 rpm to run right and fly right. I have not
been trying to fly it at rpm's below 5100, it is that (possibly due to still
breaking in?) if it gets below 5100 down to around 4000, as in when making a
descent to land, it vibrates more than it ought to. This is typically in a semi
- unloaded state, throttle retarded, engine providing minimal thrust. Once
it gets below 4000 rpm, the vibration goes away.
David & I have discussed changing the two blade Ivo to a three blade as a way to
deal with the vibration, but only if we have to. Right now we have an 800'/min
climb rate, and we would hate to have to give that up by going to a smaller
diameter prop.
As always, appreciate your input, gives us all a chance to think these things through
and stimulate the old grey matter.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=479496#479496
Message 10
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Subject: | Re: Balance Master |
Don't think I explained myself very well, as usual.
I indicated the only numbers I could find were max power. Could not find anything
for cruise power. Was not inferring the engine needed to be operated at max
power.
Not that familiar with fixed wing aircraft, but on several of the Army helicopters
I was privileged to fly there were RPM areas to stay out of. When running
up, don't hesitate in these yellow zones. 4000 to 5200 may be a similar zone
with the 277. If it was me, I'd fly Hell out of it and stay out of 4000 to 5200
except to transit that rpm.
Don't know if a 3 blade will solve your problem, but you won't know until you try.
john h
mkIII
Titus, Alabama
-----Original Message-----
From: owner-kolb-list-server@matronics.com [mailto:owner-kolb-list-server@matronics.com] On Behalf Of Richard Pike
Sent: Monday, April 23, 2018 1:00 PM
Subject: Kolb-List: Re: Balance Master
Jack Hart: What a prince! Thank you, can't wait to try it out and see how it does.
John Hauck: you are correct, I am sure that the Austrian gnomes at Gunskirchen
tuned the 277 for optimum power between 6250 and 6500, and I am sure it would
happily churn away at that speed all day. However, while 6250 - 6500 rpm is where
the engine makes its rated power, that does not necessitate the engine having
to be consistently operated at that rpm.
Here is a very good website of tutorials by the Australian light aircraft people - https://www.recreationalflying.com/tutorials/index.html
and from their page on "Engines and Propellers",
"Although aero-engines can quite happily operate continually at their rated power,
doing so is not good practice. It is uneconomical in terms of fuel efficiency,
but more importantly it may shorten engine life, if engine operating temperatures
and pressures are exceeded. Normally the maximum and optimum power
setting for continuous cruise operation is 75% of rated power."
Then they deal specifically with the 2-stroke; "Two-strokes don't have very good
volumetric efficiency, and the engine is generally efficient only in the upper
30% of its rpm and throttle opening range. In fact, ultralight two-strokes
tend to run very roughly at speeds below 2500 rpm and achieve their rated power
at rotational speeds in the 5500 to 6500 rpm range. The three most common two-strokes
are two-cylinder models with individual cylinder displacements around
250 cc; they achieve their rated power at 6500 rpm and 75% power at around 5300
rpm."
Something else to consider is that running an engine slower than its rated power
does not lug it. Once again from the recreationalflying.com tutorial page: "the
power delivered by a propeller varies in accordance with rpm cubed (if everything
else is kept constant)" Therefore, as rpm is decreased from the engine/propeller
maximum attainable rpm, the load reduction on the engine decreases
exponentially. (don't know the right technical term for a decrease cubed, but
you get the idea)
Back when I was flying a Maxair Hummer with a Rotax 277, it spent most of its time
around 54-5500 rpm. The 582 on my MKIII spends most of its time around 54-5500
rpm solo, 56-5700 rpm when I have a passenger. When I am in a hurry, it runs
at 6200 rpm and sucks gas like it was free.
The 277 on the Firefly is still breaking in, but right now it appears that the
sweet spot is going to be around 5500 rpm to run right and fly right. I have not
been trying to fly it at rpm's below 5100, it is that (possibly due to still
breaking in?) if it gets below 5100 down to around 4000, as in when making a
descent to land, it vibrates more than it ought to. This is typically in a semi
- unloaded state, throttle retarded, engine providing minimal thrust. Once
it gets below 4000 rpm, the vibration goes away.
David & I have discussed changing the two blade Ivo to a three blade as a way to
deal with the vibration, but only if we have to. Right now we have an 800'/min
climb rate, and we would hate to have to give that up by going to a smaller
diameter prop.
As always, appreciate your input, gives us all a chance to think these things through
and stimulate the old grey matter.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=479496#479496
Message 11
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|
Subject: | Re: Balance Master |
What John described is actually quite common in certified fixed wing a/c,
as well. Many that are equipped with metal constant speed props have a
'yellow arc' (usually around 2000-2200 rpm on an engine with max 2700 rpm).
While not a problem to transition through that range, continued operation
there can result in a broken crankshaft or prop. Remember, these are
FAA-blessed aircraft.
It's worth pointing out that just because you don't feel it, doesn't
necessarily mean it's not there (might not be exciting the airfame so
you're feeling it at higher rpms, but still out of balance). But if it's
bad enough to be annoying, you probably want to stay away from that speed
range; you're probably operating near the natural resonant frequency of the
system and stuff can sometimes break very quickly there.
Have you tried *dynamically* balancing the prop? It isn't cheap to pay an
a&p to do it, but many EAA chapters have one of the less expensive models
you can borrow or rent.
Charlie
On Mon, Apr 23, 2018 at 1:20 PM, John Hauck <jhauck@elmore.rr.com> wrote:
>
> Don't think I explained myself very well, as usual.
>
> I indicated the only numbers I could find were max power. Could not find
> anything for cruise power. Was not inferring the engine needed to be
> operated at max power.
>
> Not that familiar with fixed wing aircraft, but on several of the Army
> helicopters I was privileged to fly there were RPM areas to stay out of.
> When running up, don't hesitate in these yellow zones. 4000 to 5200 may
be
> a similar zone with the 277. If it was me, I'd fly Hell out of it and st
ay
> out of 4000 to 5200 except to transit that rpm.
>
> Don't know if a 3 blade will solve your problem, but you won't know until
> you try.
>
> john h
> mkIII
> Titus, Alabama
>
>
> -----Original Message-----
> From: owner-kolb-list-server@matronics.com [mailto:owner-kolb-list-
> server@matronics.com] On Behalf Of Richard Pike
> Sent: Monday, April 23, 2018 1:00 PM
> To: kolb-list@matronics.com
> Subject: Kolb-List: Re: Balance Master
>
>
>
> Jack Hart: What a prince! Thank you, can't wait to try it out and see how
> it does.
>
> John Hauck: you are correct, I am sure that the Austrian gnomes at
> Gunskirchen tuned the 277 for optimum power between 6250 and 6500, and I
am
> sure it would happily churn away at that speed all day. However, while
> 6250 - 6500 rpm is where the engine makes its rated power, that does not
> necessitate the engine having to be consistently operated at that rpm.
>
> Here is a very good website of tutorials by the Australian light aircraft
> people - https://www.recreationalflying.com/tutorials/index.html
> and from their page on "Engines and Propellers",
> "Although aero-engines can quite happily operate continually at their
> rated power, doing so is not good practice. It is uneconomical in terms o
f
> fuel efficiency, but =C3=A2=82=AC=9D more importantly =C3=A2
=82=AC=9D it may shorten engine life,
> if engine operating temperatures and pressures are exceeded. Normally the
> maximum =C3=A2=82=AC=9D and optimum =C3=A2=82=AC=9D pow
er setting for continuous cruise operation
> is 75% of rated power."
>
> Then they deal specifically with the 2-stroke; "Two-strokes don't have
> very good volumetric efficiency, and the engine is generally efficient on
ly
> in the upper 30% of its rpm and throttle opening range. In fact, ultralig
ht
> two-strokes tend to run very roughly at speeds below 2500 rpm and achieve
> their rated power at rotational speeds in the 5500 to 6500 rpm range. The
> three most common two-strokes are two-cylinder models with individual
> cylinder displacements around 250 cc; they achieve their rated power at
> 6500 rpm and 75% power at around 5300 rpm."
>
> Something else to consider is that running an engine slower than its rate
d
> power does not lug it. Once again from the recreationalflying.com
> tutorial page: "the power delivered by a propeller varies in accordance
> with rpm cubed (if everything else is kept constant)" Therefore, as rpm i
s
> decreased from the engine/propeller maximum attainable rpm, the load
> reduction on the engine decreases exponentially. (don't know the right
> technical term for a decrease cubed, but you get the idea)
>
> Back when I was flying a Maxair Hummer with a Rotax 277, it spent most of
> its time around 54-5500 rpm. The 582 on my MKIII spends most of its time
> around 54-5500 rpm solo, 56-5700 rpm when I have a passenger. When I am i
n
> a hurry, it runs at 6200 rpm and sucks gas like it was free.
>
> The 277 on the Firefly is still breaking in, but right now it appears tha
t
> the sweet spot is going to be around 5500 rpm to run right and fly right.
I
> have not been trying to fly it at rpm's below 5100, it is that (possibly
> due to still breaking in?) if it gets below 5100 down to around 4000, as
in
> when making a descent to land, it vibrates more than it ought to. This is
> typically in a semi - unloaded state, throttle retarded, engine providing
> minimal thrust. Once it gets below 4000 rpm, the vibration goes away.
>
> David & I have discussed changing the two blade Ivo to a three blade as a
> way to deal with the vibration, but only if we have to. Right now we have
> an 800'/min climb rate, and we would hate to have to give that up by goin
g
> to a smaller diameter prop.
>
> As always, appreciate your input, gives us all a chance to think these
> things through and stimulate the old grey matter.
>
> --------
> Richard Pike
> Kolb MKIII N420P (420ldPoops)
> Kingsport, TN 3TN0
>
> Forgiving is tough, being forgiven is wonderful, and God's grace really i
s
> amazing.
>
>
Message 12
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Subject: | Re: Balance Master |
There are several FAA certified airplanes with fixed pitch metal propellers that
also have those "caution" and "avoid" ranges of RPM. The mathematics and engineering
for figuring that out are way above anything I can understand, but I
know that these vibration and resonance issues are very real.
There is a famous video of Sikorsky doing "ground resonance testing" on a Chinook
(I believe) where the helicopter just tears itself apart on the ground. Terrifying
spectacle. John H I hope you were not the test pilot sitting in that aircraft
in that video !!! I needed a change of underwear just watching the video
on a computer...
Bill Berle
www.ezflaphandle.com - safety & performance upgrade for light aircraft
www.grantstar.net - winning proposals for non-profit and for-profit entities
--------------------------------------------
On Mon, 4/23/18, Charlie England <ceengland7@gmail.com> wrote:
Subject: Re: Kolb-List: Re: Balance Master
To: kolb-list@matronics.com
Date: Monday, April 23, 2018, 11:45 AM
What John described
is actually quite common in certified fixed wing a/c, as
well. Many that are equipped with metal constant speed props
have a 'yellow arc' (usually around 2000-2200 rpm on
an engine with max 2700 rpm). While not a problem to
transition through that range, continued operation there can
result in a broken crankshaft or prop. Remember, these are
FAA-blessed aircraft.
It's worth pointing out that just because you
don't feel it, doesn't necessarily mean it's not
there (might not be exciting the airfame so you're
feeling it at higher rpms, but still out of balance). But if
it's bad enough to be annoying, you probably want to
stay away from that speed range; you're probably
operating near the natural resonant frequency of the system
and stuff can sometimes break very quickly
there.
Have you tried *dynamically* balancing the prop?
It isn't cheap to pay an a&p to do it, but many EAA
chapters have one of the less expensive models you can
borrow or rent.
Charlie
On Mon, Apr 23, 2018
at 1:20 PM, John Hauck <jhauck@elmore.rr.com>
wrote:
"John Hauck" <jhauck@elmore.rr.com>
Don't think I explained myself very well, as usual.
I indicated the only numbers I could find were max power.
Could not find anything for cruise power. Was not
inferring the engine needed to be operated at max power.
Not that familiar with fixed wing aircraft, but on several
of the Army helicopters I was privileged to fly there were
RPM areas to stay out of. When running up, don't
hesitate in these yellow zones. 4000 to 5200 may be a
similar zone with the 277. If it was me, I'd fly Hell
out of it and stay out of 4000 to 5200 except to transit
that rpm.
Don't know if a 3 blade will solve your problem, but you
won't know until you try.
john h
mkIII
Titus, Alabama
-----Original Message-----
From: owner-kolb-list-server@
matronics.com [mailto:owner-kolb-list-
server@matronics.com] On Behalf Of Richard Pike
Sent: Monday, April 23, 2018 1:00 PM
To: kolb-list@matronics.com
Subject: Kolb-List: Re: Balance Master
<thegreybaron@charter.net>
Jack Hart: What a prince! Thank you, can't wait to try
it out and see how it does.
John Hauck: you are correct, I am sure that the Austrian
gnomes at Gunskirchen tuned the 277 for optimum power
between 6250 and 6500, and I am sure it would happily churn
away at that speed all day. However, while 6250 - 6500 rpm
is where the engine makes its rated power, that does not
necessitate the engine having to be consistently operated at
that rpm.
Here is a very good website of tutorials by the Australian
light aircraft people - https://www.
recreationalflying.com/ tutorials/index.html
and from their page on "Engines and Propellers",
"Although aero-engines can quite happily operate
continually at their rated power, doing so is not good
practice. It is uneconomical in terms of fuel efficiency,
but more importantly it may shorten engine
life, if engine operating temperatures and pressures are
exceeded. Normally the maximum and optimum
power setting for continuous cruise operation is 75% of
rated power."
Then they deal specifically with the 2-stroke;
"Two-strokes don't have very good volumetric
efficiency, and the engine is generally efficient only in
the upper 30% of its rpm and throttle opening range. In
fact, ultralight two-strokes tend to run very roughly at
speeds below 2500 rpm and achieve their rated power at
rotational speeds in the 5500 to 6500 rpm range. The three
most common two-strokes are two-cylinder models with
individual cylinder displacements around 250 cc; they
achieve their rated power at 6500 rpm and 75% power at
around 5300 rpm."
Something else to consider is that running an engine slower
than its rated power does not lug it. Once again from the recreationalflying.com
tutorial page: "the power delivered by a propeller
varies in accordance with rpm cubed (if everything else is
kept constant)" Therefore, as rpm is decreased from the
engine/propeller maximum attainable rpm, the load reduction
on the engine decreases exponentially. (don't know the
right technical term for a decrease cubed, but you get the
idea)
Back when I was flying a Maxair Hummer with a Rotax 277, it
spent most of its time around 54-5500 rpm. The 582 on my
MKIII spends most of its time around 54-5500 rpm solo,
56-5700 rpm when I have a passenger. When I am in a hurry,
it runs at 6200 rpm and sucks gas like it was free.
The 277 on the Firefly is still breaking in, but right now
it appears that the sweet spot is going to be around 5500
rpm to run right and fly right. I have not been trying to
fly it at rpm's below 5100, it is that (possibly due to
still breaking in?) if it gets below 5100 down to around
4000, as in when making a descent to land, it vibrates more
than it ought to. This is typically in a semi - unloaded
state, throttle retarded, engine providing minimal thrust.
Once it gets below 4000 rpm, the vibration goes away.
David & I have discussed changing the two blade Ivo to a
three blade as a way to deal with the vibration, but only if
we have to. Right now we have an 800'/min climb rate,
and we would hate to have to give that up by going to a
smaller diameter prop.
As always, appreciate your input, gives us all a chance to
think these things through and stimulate the old grey
matter.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Forgiving is tough, being forgiven is wonderful, and
God's grace really is amazing.
Message 13
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Subject: | Re: Firestar 2 / HKS engine progress |
Just a quick update on my HKS installation in the Firestar. After waiting months
for the guy to be available, I finally had the last of the exhaust parts fabricated
and welded!
So now I have two 1.25" stainless exhaust pipes coming down from the engine exhaust
ports, joining together and running down the rear of the fuselage cage, then
a 2-into-1 collector at the right "tuning" location, then a 1.5" diameter
"flex coupler", then a length of stainless tube that swings down and around to
the bottom of the tailboom (fuselage tube), which then inserts into the front
of the home made "Swiss Muffler" exhaust silencer.
whew !
Now that the exhaust is complete, I will re-mount it on the aircraft and I can
finally do a weight and balance to see where I have to mount the battery. I have
waited to mo unt the battery because I literally have no idea whether it's
nose-heavy or tail-heavy.
With a little luck and no major obstacles, the Firestar should be ready for flight
testing by this summer.
Bill Berle
www.ezflaphandle.com - safety & performance upgrade for light aircraft
www.grantstar.net - winning proposals for non-profit and for-profit entities
--------------------------------------------
On Mon, 4/23/18, Charlie England <ceengland7@gmail.com> wrote:
Subject: Re: Kolb-List: Re: Balance Master
To: kolb-list@matronics.com
Date: Monday, April 23, 2018, 11:45 AM
What John described
is actually quite common in certified fixed wing a/c, as
well. Many that are equipped with metal constant speed props
have a 'yellow arc' (usually around 2000-2200 rpm on
an engine with max 2700 rpm). While not a problem to
transition through that range, continued operation there can
result in a broken crankshaft or prop. Remember, these are
FAA-blessed aircraft.
It's worth pointing out that just because you
don't feel it, doesn't necessarily mean it's not
there (might not be exciting the airfame so you're
feeling it at higher rpms, but still out of balance). But if
it's bad enough to be annoying, you probably want to
stay away from that speed range; you're probably
operating near the natural resonant frequency of the system
and stuff can sometimes break very quickly
there.
Have you tried *dynamically* balancing the prop?
It isn't cheap to pay an a&p to do it, but many EAA
chapters have one of the less expensive models you can
borrow or rent.
Charlie
On Mon, Apr 23, 2018
at 1:20 PM, John Hauck <jhauck@elmore.rr.com>
wrote:
"John Hauck" <jhauck@elmore.rr.com>
Don't think I explained myself very well, as usual.
I indicated the only numbers I could find were max power.
Could not find anything for cruise power. Was not
inferring the engine needed to be operated at max power.
Not that familiar with fixed wing aircraft, but on several
of the Army helicopters I was privileged to fly there were
RPM areas to stay out of. When running up, don't
hesitate in these yellow zones. 4000 to 5200 may be a
similar zone with the 277. If it was me, I'd fly Hell
out of it and stay out of 4000 to 5200 except to transit
that rpm.
Don't know if a 3 blade will solve your problem, but you
won't know until you try.
john h
mkIII
Titus, Alabama
-----Original Message-----
From: owner-kolb-list-server@
matronics.com [mailto:owner-kolb-list-
server@matronics.com] On Behalf Of Richard Pike
Sent: Monday, April 23, 2018 1:00 PM
To: kolb-list@matronics.com
Subject: Kolb-List: Re: Balance Master
<thegreybaron@charter.net>
Jack Hart: What a prince! Thank you, can't wait to try
it out and see how it does.
John Hauck: you are correct, I am sure that the Austrian
gnomes at Gunskirchen tuned the 277 for optimum power
between 6250 and 6500, and I am sure it would happily churn
away at that speed all day. However, while 6250 - 6500 rpm
is where the engine makes its rated power, that does not
necessitate the engine having to be consistently operated at
that rpm.
Here is a very good website of tutorials by the Australian
light aircraft people - https://www.
recreationalflying.com/ tutorials/index.html
and from their page on "Engines and Propellers",
"Although aero-engines can quite happily operate
continually at their rated power, doing so is not good
practice. It is uneconomical in terms of fuel efficiency,
but more importantly it may shorten engine
life, if engine operating temperatures and pressures are
exceeded. Normally the maximum and optimum
power setting for continuous cruise operation is 75% of
rated power."
Then they deal specifically with the 2-stroke;
"Two-strokes don't have very good volumetric
efficiency, and the engine is generally efficient only in
the upper 30% of its rpm and throttle opening range. In
fact, ultralight two-strokes tend to run very roughly at
speeds below 2500 rpm and achieve their rated power at
rotational speeds in the 5500 to 6500 rpm range. The three
most common two-strokes are two-cylinder models with
individual cylinder displacements around 250 cc; they
achieve their rated power at 6500 rpm and 75% power at
around 5300 rpm."
Something else to consider is that running an engine slower
than its rated power does not lug it. Once again from the recreationalflying.com
tutorial page: "the power delivered by a propeller
varies in accordance with rpm cubed (if everything else is
kept constant)" Therefore, as rpm is decreased from the
engine/propeller maximum attainable rpm, the load reduction
on the engine decreases exponentially. (don't know the
right technical term for a decrease cubed, but you get the
idea)
Back when I was flying a Maxair Hummer with a Rotax 277, it
spent most of its time around 54-5500 rpm. The 582 on my
MKIII spends most of its time around 54-5500 rpm solo,
56-5700 rpm when I have a passenger. When I am in a hurry,
it runs at 6200 rpm and sucks gas like it was free.
The 277 on the Firefly is still breaking in, but right now
it appears that the sweet spot is going to be around 5500
rpm to run right and fly right. I have not been trying to
fly it at rpm's below 5100, it is that (possibly due to
still breaking in?) if it gets below 5100 down to around
4000, as in when making a descent to land, it vibrates more
than it ought to. This is typically in a semi - unloaded
state, throttle retarded, engine providing minimal thrust.
Once it gets below 4000 rpm, the vibration goes away.
David & I have discussed changing the two blade Ivo to a
three blade as a way to deal with the vibration, but only if
we have to. Right now we have an 800'/min climb rate,
and we would hate to have to give that up by going to a
smaller diameter prop.
As always, appreciate your input, gives us all a chance to
think these things through and stimulate the old grey
matter.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Forgiving is tough, being forgiven is wonderful, and
God's grace really is amazing.
Message 14
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Subject: | Re: Balance Master |
This one? https://www.youtube.com/watch?v=0FeXjhUEXlc
Or maybe this one? https://www.youtube.com/watch?v=RihcJR0zvfM
Congratulations on surviving!
victorbravo(at)sbcglobal. wrote:
> There are several FAA certified airplanes with fixed pitch metal propellers that
also have those "caution" and "avoid" ranges of RPM. The mathematics and engineering
for figuring that out are way above anything I can understand, but
I know that these vibration and resonance issues are very real.
>
> There is a famous video of Sikorsky doing "ground resonance testing" on a Chinook
(I believe) where the helicopter just tears itself apart on the ground. Terrifying
spectacle. John H I hope you were not the test pilot sitting in that
aircraft in that video !!! I needed a change of underwear just watching the video
on a computer...
>
> Bill Berle
>
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=479503#479503
Message 15
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Subject: | Re: Balance Master |
No, this one: https://www.youtube.com/watch?v=D2tHA7KmRME
Bill Berle
www.ezflaphandle.com - safety & performance upgrade for light aircraft
www.grantstar.net - winning proposals for non-profit and for-profit entities
--------------------------------------------
On Mon, 4/23/18, Richard Pike <thegreybaron@charter.net> wrote:
Subject: Kolb-List: Re: Balance Master
To: kolb-list@matronics.com
Date: Monday, April 23, 2018, 4:50 PM
Pike" <thegreybaron@charter.net>
This one? https://www.youtube.com/watch?v=0FeXjhUEXlc
Or maybe this one? https://www.youtube.com/watch?v=RihcJR0zvfM
Congratulations on surviving!
victorbravo(at)sbcglobal. wrote:
> There are several FAA certified
airplanes with fixed pitch metal propellers that also have
those "caution" and "avoid" ranges of RPM. The mathematics
and engineering for figuring that out are way above anything
I can understand, but I know that these vibration and
resonance issues are very real.
>
> There is a famous video of
Sikorsky doing "ground resonance testing" on a Chinook (I
believe) where the helicopter just tears itself apart on the
ground. Terrifying spectacle. John H I hope you were not the
test pilot sitting in that aircraft in that video !!! I
needed a change of underwear just watching the video on a
computer...
>
> Bill Berle
>
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Forgiving is tough, being forgiven is
wonderful, and God's grace really is amazing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=479503#479503
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