Today's Message Index:
----------------------
1. 08:28 AM - Re-Pitch to 17-degrees on a 601 with a Stratus (Larry McFarland)
2. 08:38 AM - Re: Re-Pitch to 17-degrees on a 601 with a Stratus (rueffy@jetthrust.com)
3. 09:43 AM - Re: Re-Pitch to 17-degrees on a 601 with a (Jim and Lucy)
4. 05:02 PM - Re: Re-Pitch to 17-degrees on a 601 with a Stratus (Larry McFarland)
5. 07:30 PM - engine fuel burn and horsepower (Jim and Lucy)
6. 07:41 PM - engine fuel burn and horsepower (Jim and Lucy)
Message 1
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| Subject: | Re-Pitch to 17-degrees on a 601 with a Stratus |
--> Stratus-List message posted by: Larry McFarland <larrymc@qconline.com>
Hi guys,
I've not gotten out of testing yet, even with 70 hours on the HDS.
Yesterday, I re-pitched the 3-blade 70" Warp Drive on my Stratus to
17-degrees
and flew it this morning. At 85-degrees ambient, I was impressed with
the performance.
The most surprising thing was that prop noise is considerably lower at
this setting.
The water temp EIS warning light had to be reset to 110-degrees F, oil
reached 235-deg.
Climb-out, usually 80 mph at 900 fpm and 4900 rpm, needed only 4800 rpm
to reach
the same rate of climb at near 90 mph. I leveled out in very smooth air
at 2500 feet
and could easily add 5 mph to every set point. I didn't run at full
5100 rpm at this pitch.
It was easy to move thru 118 mph at 4650 and just stay at 2500 feet with
the nose angled
a bit lower. I would have said 16-degrees was the sweet spot, but
17-degrees is better.
Lift-off is just as short, climb is the same, just faster, on less rpm.
I'd like to increase
pitch another half-degree or so to see where it begins to affect
lift-off distance and rate
of climb. Oil and coolant were the only temps that got noticeably higher
and none went past
normal mid-high ranges. It's the best time of year to test the long
pitch settings
because this heat offers the least effective air for lift and pull. In
56 minutes the
Stratus burned 4 gallons of 87-octane at a cruise set mostly at 4650 rpm
and
I'd only be guessing that 85-90 horsepower is developed at that rpm.
Best regards,
Larry McFarland - 601HDS at www.macsmachine.com
This was sent yesterday, but didn't post for some reason.
Message 2
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| Subject: | Re: Re-Pitch to 17-degrees on a 601 with a Stratus |
--> Stratus-List message posted by: rueffy@jetthrust.com
Thanks Larry, appreciate the figures. I'd be interested to hear at what point
the pitch begins to adversely effect takeoff roll.
Brett
Quoting Larry McFarland <larrymc@qconline.com>:
> --> Stratus-List message posted by: Larry McFarland <larrymc@qconline.com>
>
> Hi guys,
> I've not gotten out of testing yet, even with 70 hours on the HDS.
> Yesterday, I re-pitched the 3-blade 70" Warp Drive on my Stratus to
> 17-degrees
> and flew it this morning. At 85-degrees ambient, I was impressed with
> the performance.
> The most surprising thing was that prop noise is considerably lower at
> this setting.
> The water temp EIS warning light had to be reset to 110-degrees F, oil
> reached 235-deg.
> Climb-out, usually 80 mph at 900 fpm and 4900 rpm, needed only 4800 rpm
> to reach
> the same rate of climb at near 90 mph. I leveled out in very smooth air
> at 2500 feet
> and could easily add 5 mph to every set point. I didn't run at full
> 5100 rpm at this pitch.
> It was easy to move thru 118 mph at 4650 and just stay at 2500 feet with
> the nose angled
> a bit lower. I would have said 16-degrees was the sweet spot, but
> 17-degrees is better.
> Lift-off is just as short, climb is the same, just faster, on less rpm.
> I'd like to increase
> pitch another half-degree or so to see where it begins to affect
> lift-off distance and rate
> of climb. Oil and coolant were the only temps that got noticeably higher
> and none went past
> normal mid-high ranges. It's the best time of year to test the long
> pitch settings
> because this heat offers the least effective air for lift and pull. In
> 56 minutes the
> Stratus burned 4 gallons of 87-octane at a cruise set mostly at 4650 rpm
> and
> I'd only be guessing that 85-90 horsepower is developed at that rpm.
>
> Best regards,
>
> Larry McFarland - 601HDS at www.macsmachine.com
>
> This was sent yesterday, but didn't post for some reason.
>
>
>
>
>
>
>
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Message 3
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| Subject: | Re: Re-Pitch to 17-degrees on a 601 with a |
Stratus
--> Stratus-List message posted by: Jim and Lucy <jpollard@ciaccess.com>
At 11:27 AM 9/8/2005, you wrote:
> In
>56 minutes the
>Stratus burned 4 gallons of 87-octane at a cruise set mostly at 4650 rpm
>and
>I'd only be guessing that 85-90 horsepower is developed at that rpm.
4 gallons per hour = about 48 horsepower
4 gallons X 6 lbs per gallon X 2 horsepower per lb. of fuel per hour
Jim Pollard
Message 4
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| Subject: | Re: Re-Pitch to 17-degrees on a 601 with a Stratus |
--> Stratus-List message posted by: Larry McFarland <larrymc@qconline.com>
You seem to have a handle on this Jim. I wrote from what I remember of
graphs for the ea-81. Actual horsepower that doesn't get lost in heat or
exhaust is about 60% of that which would, by fuel burn numbers, say that
an unmodified Subaru or any other engine should have a work output of
38.5 to 66 actual horsepower if the fuel burn range is 3.2 to 5 gallons
per hour. 80-hp ratings would seem to be BTU to HP conversion estimates
while actual work measured on a Dyno might be 48 or so. Do you have an
idea of how most ratings for these engines are generally derived? I'm
not an engine guy but I am curious.
respectfully,
Larry McFarland
do not archive
Jim and Lucy wrote:
>--> Stratus-List message posted by: Jim and Lucy <jpollard@ciaccess.com>
>
>At 11:27 AM 9/8/2005, you wrote:
>
>
>> In
>>56 minutes the
>>Stratus burned 4 gallons of 87-octane at a cruise set mostly at 4650 rpm
>>and
>>I'd only be guessing that 85-90 horsepower is developed at that rpm.
>>
>>
>
>
>4 gallons per hour = about 48 horsepower
>
>4 gallons X 6 lbs per gallon X 2 horsepower per lb. of fuel per hour
>
>
>Jim Pollard
>
>
>
>
Message 5
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| Subject: | engine fuel burn and horsepower |
--> Stratus-List message posted by: Jim and Lucy <jpollard@ciaccess.com>
--> Stratus-List message posted by: Larry McFarland <larrymc@qconline.com>
You seem to have a handle on this Jim. I wrote from what I remember of
graphs for the ea-81. Actual horsepower that doesn't get lost in heat or
exhaust is about 60% of that which would, by fuel burn numbers, say that
an unmodified Subaru or any other engine should have a work output of
38.5 to 66 actual horsepower if the fuel burn range is 3.2 to 5 gallons
per hour. 80-hp ratings would seem to be BTU to HP conversion estimates
while actual work measured on a Dyno might be 48 or so. Do you have an
idea of how most ratings for these engines are generally derived? I'm
not an engine guy but I am curious.
respectfully,
Larry McFarland
do not
The factory certainly must put them on a dyno and measure torque and
rpm to calculate the hp. Now this does not mean that you can compare
one manufacturers numbers with another. There are many variables
like temp and airpressure which can change the results. It is also
possible that the waterpump or alternators may be not used in the
test depending what the test was designed to find out. I think
you are saying that by the rpm you test flew at that the engine
should be putting out a certain hp because a hp torque graph
showed that amount. Possibly the problem with that is because
the engine is not necessarily putting out that much hp because
at that prop engine speed combination the engine is not loaded
at the same amount as it was when they took the reading to
graph that particular point on the hp chart. There are standards
for doing this but its hard to tell what standards they used when
you see something like the Japanese factory soob graphs. They are
useful to compare one engine to another in a broad since. Also
very useful for a lab when comparing one engine run to another
using the same dyno.
An extreme example of this would be to take an engine with nothing
at all hooked to the output side and run it at that rpm. It is
not putting out anything much powerwise so it would be making
very little hp. So the fuel burn would be small.
It takes fuel to make hp. There are certain constant range of fuel burn
and hp. If someone tells you that their fuel burn and hp are outside
of this range they are wrong somehow in their figures.
For instance a modern engine will be close to 0.5 lbs per hp per hour.
Some are a bit better some are a bit worse. It also depends on what
rpm range and throttle valve position the engine is running in.
An example is a 100 hp engine running at 75 percent power. At 75 hp
that would be 75 hp times 0.5 which is 37.5 lbs of gasoline which is
a bit over 6 gallons per hour.
You can take the fuel burn and multiply by 12 to get close to your
hp output from a steady state engine run.
The charts in a pilots operating handbook are made with the all the
variables that affect the fuel burns taken into account when they
do the testing at the factory. What we can not tell for sure is
the amount of torque going into the prop at a particular throttle
setting or rpm. It would be quite difficult to measure this for
us non factory laboratory equipped folks.
So the next best thing is to use the fuel burn to estimate at the
hp. If the engine and carbs are tuned well this will be close enough.
An engine has a certain area where it runs the most efficiently. Usually
it is with wide open throttle valve because the engine does not need
to work against this restriction to pull the air in.(high manifold pressure).
If you want to run at 75% power the way most efficiently is to climb to
whatever
altitude gives you that at wide open throttle (wot).
Some engine with fixed mixture carbs do not run most efficiently at wot
because the carbs are set up to go richer at this setting due to
engine heating considerations and uneven mixture distribution to all the
cylinders. This is more of an effect on ground vehicle designed carbs like
the one I am using for my soob.
Some times a manufacturer of engines will say that their 100 hp engine
burns 4 gallons per hour at 75% throttle. This may well be correct but
it is not the same as saying 75% power. Of course here the difference is
75% throttle does not equal 75% power. In this case it would be about
48 to 50 hp. They know this or they should since they are professional
engine men but it sounds better for sales.
Sometimes when I am flying down the road in my big gas guzzling farm
pickup that gets 15 miles per gallon i do the quick calculation in my
head of how much hp it is using to do this. It works out to 4 gallons
per hour at 60mph and something like 48 hp pushing all that air and
weight and turning the large engine and gearing etc.
The most efficient practical gasoline engine was around 0.39 lbs per
hp per hour (BSFC). A very large engine with an exhaust turbine that
captured some of the waisted energy and fed it back into the crank.
A fairly inefficient engine would run around 0.54 so i pick .50 because
it is easy to work out in your head and you can add or subtract a few
percent to it easy after you get your number depending on how efficient
the engine you are working with is.
If a number any engine manufacturer gives you is out of this range it is
likely bogus. Even if below about .42 I would question it.
Jim Pollard
Merlin Ont
ch601hds
ea81
Message 6
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| Subject: | engine fuel burn and horsepower |
--> Stratus-List message posted by: Jim and Lucy <jpollard@ciaccess.com>
--> Stratus-List message posted by: Larry McFarland <larrymc@qconline.com>
You seem to have a handle on this Jim. I wrote from what I remember of
graphs for the ea-81. Actual horsepower that doesn't get lost in heat or
exhaust is about 60% of that which would, by fuel burn numbers, say that
an unmodified Subaru or any other engine should have a work output of
38.5 to 66 actual horsepower if the fuel burn range is 3.2 to 5 gallons
per hour. 80-hp ratings would seem to be BTU to HP conversion estimates
while actual work measured on a Dyno might be 48 or so. Do you have an
idea of how most ratings for these engines are generally derived? I'm
not an engine guy but I am curious.
respectfully,
Larry McFarland
do not
The factory certainly must put them on a dyno and measure torque and
rpm to calculate the hp. Now this does not mean that you can compare
one manufacturers numbers with another. There are many variables
like temp and airpressure which can change the results. It is also
possible that the waterpump or alternators may be not used in the
test depending what the test was designed to find out. I think
you are saying that by the rpm you test flew at that the engine
should be putting out a certain hp because a hp torque graph
showed that amount. Possibly the problem with that is because
the engine is not necessarily putting out that much hp because
at that prop engine speed combination the engine is not loaded
at the same amount as it was when they took the reading to
graph that particular point on the hp chart. There are standards
for doing this but its hard to tell what standards they used when
you see something like the Japanese factory soob graphs. They are
useful to compare one engine to another in a broad since. Also
very useful for a lab when comparing one engine run to another
using the same dyno.
An extreme example of this would be to take an engine with nothing
at all hooked to the output side and run it at that rpm. It is
not putting out anything much powerwise so it would be making
very little hp. So the fuel burn would be small.
It takes fuel to make hp. There are certain constant range of fuel burn
and hp. If someone tells you that their fuel burn and hp are outside
of this range they are wrong somehow in their figures.
For instance a modern engine will be close to 0.5 lbs per hp per hour.
Some are a bit better some are a bit worse. It also depends on what
rpm range and throttle valve position the engine is running in.
An example is a 100 hp engine running at 75 percent power. At 75 hp
that would be 75 hp times 0.5 which is 37.5 lbs of gasoline which is
a bit over 6 gallons per hour.
You can take the fuel burn and multiply by 12 to get close to your
hp output from a steady state engine run.
The charts in a pilots operating handbook are made with the all the
variables that affect the fuel burns taken into account when they
do the testing at the factory. What we can not tell for sure is
the amount of torque going into the prop at a particular throttle
setting or rpm. It would be quite difficult to measure this for
us non factory laboratory equipped folks.
So the next best thing is to use the fuel burn to estimate at the
hp. If the engine and carbs are tuned well this will be close enough.
An engine has a certain area where it runs the most efficiently. Usually
it is with wide open throttle valve because the engine does not need
to work against this restriction to pull the air in.(high manifold pressure).
If you want to run at 75% power the way most efficiently is to climb to
whatever
altitude gives you that at wide open throttle (wot).
Some engine with fixed mixture carbs do not run most efficiently at wot
because the carbs are set up to go richer at this setting due to
engine heating considerations and uneven mixture distribution to all the
cylinders. This is more of an effect on ground vehicle designed carbs like
the one I am using for my soob.
Some times a manufacturer of engines will say that their 100 hp engine
burns 4 gallons per hour at 75% throttle. This may well be correct but
it is not the same as saying 75% power. Of course here the difference is
75% throttle does not equal 75% power. In this case it would be about
48 to 50 hp. They know this or they should since they are professional
engine men but it sounds better for sales.
Sometimes when I am flying down the road in my big gas guzzling farm
pickup that gets 15 miles per gallon i do the quick calculation in my
head of how much hp it is using to do this. It works out to 4 gallons
per hour at 60mph and something like 48 hp pushing all that air and
weight and turning the large engine and gearing etc.
The most efficient practical gasoline engine was around 0.39 lbs per
hp per hour (BSFC). A very large engine with an exhaust turbine that
captured some of the waisted energy and fed it back into the crank.
A fairly inefficient engine would run around 0.54 so i pick .50 because
it is easy to work out in your head and you can add or subtract a few
percent to it easy after you get your number depending on how efficient
the engine you are working with is.
If a number any engine manufacturer gives you is out of this range it is
likely bogus. Even if below about .42 I would question it.
Jim Pollard
Merlin Ont
ch601hds
ea81
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