Today's Message Index:
----------------------
1. 05:59 AM - Re: Engine break-in with a fixed-pitch prop (Gary Casey)
2. 07:22 AM - Re: Re: LycomingEngines-List Digest: 0 Msgs - 05/11/08 (Doug Dodson)
3. 08:03 AM - Re: Re: Engine break-in with a fixed-pitch prop (manuel weber)
Message 1
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| Subject: | Re: Engine break-in with a fixed-pitch prop |
With a fixed-pitch prop you don't have a lot of choice. The engine
power is roughly the rpm times manifold pressure and they can be
controlled independently with a constant-speed prop. If 29 inches
and 2700 rpm are 100% power then 75% (the usual suggested by engine
rebuilders) would be about 2600 and 23 inches, 2500 and 24 inches,
etc. If you at 3,000 ft you might be able to run at a manifold
pressure of 26 inches - 75% power would then be at an rpm of
approximately 2250, but I doubt that you can operate there with the
fixed prop. If you can fly at 6,000 ft full throttle and not go over
2500 then you're there, otherwise not. If your plane is equipped
with a manifold pressure gage then you can at least see what you
have. Note that I rounded everything off - it just isn't worth more
accuracy than that (in spite of what some engine rebuilders would
say). I suggest just go up and fly it at the highest power
comfortable without going over the engine redline; just keep it rich
to avoid high temperatures. There just isn't much else you can do.
Gary Casey
>
>
> I have a topped O-360-A1A (180 HP) in an experimental amateur-built
> that
> is ready for its first flight. The prop is fixed pitch and I don't
> have
> a manifold pressure gauge in the panel. I want to prepare a simple
> table of RPM at various pressure altitudes to yield 65% (117 HP)
> and 75%
> (135 HP) power so that I can set the power appropriately for the first
> few hours on the engine to set the rings properly.
>
> I have the Lycoming Operator's Manual (Publication No. 60297-12,
> Revision -6/7th Edition). I'm trying to decipher Figure 3-17, Sea
> Level
> and Altitude Performance on Page 3-33. By my reading it seems like I
> can generate 75% power at less than 2000 RPM up to a pressure altitude
> of about 3000 feet and pull 65% power at 2000 RPM at 7500 feet
> pressure
> altitude. That RPM seems way too low to generate those power levels.
>
> Do any of you have the right power settings for an O-360 180 HP fixed
> pitch set-up? The prop is a Sensenich 74" diameter and the pitch
> is 65"
> if I recall correctly (the pitch between climb and cruise).
>
> Or can someone tell me how to properly interpret the table? My
> inclination is to run it at 2700 RPM for take-off and then reduce
> it to
> 2500 RPM from then on out and then vary the RPM +/- 100 RPM every half
> hour or so. I'll be operating at pressure altitudes of between sea
> level and 5000 feet.
>
> Bob
>
Message 2
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| Subject: | Re: LycomingEngines-List Digest: 0 Msgs - 05/11/08 |
With a fixed pitch propeller, setting the throttle to 2000 RPM will
result in a manifold pressure much less than atmospheric pressure. I
don't think those charts can be used without knowing the manifold
pressure.
Douglas L. Dodson, Jr.
Glasair II-S FT
Flight Test Engineer, CFI-A/S&ME,I,G
-----Original Message-----
From: owner-lycomingengines-list-server@matronics.com
[mailto:owner-lycomingengines-list-server@matronics.com] On Behalf Of r
falstad
Sent: Monday, May 12, 2008 7:50 PM
Subject: LycomingEngines-List: Re: LycomingEngines-List Digest: 0 Msgs -
05/11/08
I have a topped O-360-A1A (180 HP) in an experimental amateur-built that
is ready for its first flight. The prop is fixed pitch and I don't have
a manifold pressure gauge in the panel. I want to prepare a simple
table of RPM at various pressure altitudes to yield 65% (117 HP) and 75%
(135 HP) power so that I can set the power appropriately for the first
few hours on the engine to set the rings properly.
I have the Lycoming Operator's Manual (Publication No. 60297-12,
Revision -6/7th Edition). I'm trying to decipher Figure 3-17, Sea Level
and Altitude Performance on Page 3-33. By my reading it seems like I
can generate 75% power at less than 2000 RPM up to a pressure altitude
of about 3000 feet and pull 65% power at 2000 RPM at 7500 feet pressure
altitude. That RPM seems way too low to generate those power levels.
Do any of you have the right power settings for an O-360 180 HP fixed
pitch set-up? The prop is a Sensenich 74" diameter and the pitch is 65"
if I recall correctly (the pitch between climb and cruise).
Or can someone tell me how to properly interpret the table? My
inclination is to run it at 2700 RPM for take-off and then reduce it to
2500 RPM from then on out and then vary the RPM +/- 100 RPM every half
hour or so. I'll be operating at pressure altitudes of between sea
level and 5000 feet.
Bob
Message 3
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| Subject: | Re: Engine break-in with a fixed-pitch prop |
Completely agree with Gary.
You could also borrow a prop with a couple extra inches in it for break in purposes
if 65" put you in between the cruise and climb category. Keep take-off
performance in mind here...(short strip...etc.)
It is imperative that you apply as much manifold pressure as you can given engine
temp and altitude restrictions. You are not going to hurt the engine running
it at red line RPM. Do not baby the engine.
I have always tried to stay below 5000 feet with fixed pitch combinations and
keep a close eye on the temps.
Gary Casey <glcasey@adelphia.net> wrote:
With a fixed-pitch prop you don't have a lot of choice. The engine power is
roughly the rpm times manifold pressure and they can be controlled independently
with a constant-speed prop. If 29 inches and 2700 rpm are 100% power then
75% (the usual suggested by engine rebuilders) would be about 2600 and 23 inches,
2500 and 24 inches, etc. If you at 3,000 ft you might be able to run at a
manifold pressure of 26 inches - 75% power would then be at an rpm of approximately
2250, but I doubt that you can operate there with the fixed prop. If you
can fly at 6,000 ft full throttle and not go over 2500 then you're there, otherwise
not. If your plane is equipped with a manifold pressure gage then you
can at least see what you have. Note that I rounded everything off - it just
isn't worth more accuracy than that (in spite of what some engine rebuilders
would say). I suggest just go up and fly it at the highest power comfortable
without going over the engine redline; just keep
it rich to avoid high temperatures. There just isn't much else you can do. Gary
Casey
I have a topped O-360-A1A (180 HP) in an experimental amateur-built that
is ready for its first flight. The prop is fixed pitch and I don't have
a manifold pressure gauge in the panel. I want to prepare a simple
table of RPM at various pressure altitudes to yield 65% (117 HP) and 75%
(135 HP) power so that I can set the power appropriately for the first
few hours on the engine to set the rings properly.
I have the Lycoming Operator's Manual (Publication No. 60297-12,
Revision -6/7th Edition). I'm trying to decipher Figure 3-17, Sea Level
and Altitude Performance on Page 3-33. By my reading it seems like I
can generate 75% power at less than 2000 RPM up to a pressure altitude
of about 3000 feet and pull 65% power at 2000 RPM at 7500 feet pressure
altitude. That RPM seems way too low to generate those power levels.
Do any of you have the right power settings for an O-360 180 HP fixed
pitch set-up? The prop is a Sensenich 74" diameter and the pitch is 65"
if I recall correctly (the pitch between climb and cruise).
Or can someone tell me how to properly interpret the table? My
inclination is to run it at 2700 RPM for take-off and then reduce it to
2500 RPM from then on out and then vary the RPM +/- 100 RPM every half
hour or so. I'll be operating at pressure altitudes of between sea
level and 5000 feet.
Bob
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