First 100 hours

Mike Rapoport wrote:

wrote in message
news:nfKod.2604$6m2.1574@trnddc04...

On 22-Nov-2004, "Jim Burns" wrote:


On short hops of 1 hour or less we're seeing fuel burns of 20 gallons per
hour, longer hops we see 24 gallons at 24 squared and 155kts true. Push
everything forward and we see 175 knots true at around 6000 ft and fuel
burns of 27 gallons per hour. Surprisingly close to book numbers for a
38
year old airplane.

So, at the high end of the power/fuel consumption curve you are gaining 20
kts TAS for only 3 gph? That's incredible! In my relatively efficient
Arrow I gain only about 6 kts TAS for about 2 GPH going from 65% to 75%
power. How do you do it?

--
-Elliott Drucker


27GPH-20GPH=7GPH


Huh!?! Are my eyes funny, or doesn't his original post reference *24*
GPH at 155 kts vs. 27 GPH at 175 kts?

inquiring minds...
Scott Skylane

"Scott Skylane" wrote in message
...
Mike Rapoport wrote:

wrote in message
news:nfKod.2604$6m2.1574@trnddc04...

On 22-Nov-2004, "Jim Burns" wrote:


On short hops of 1 hour or less we're seeing fuel burns of 20 gallons
per
hour, longer hops we see 24 gallons at 24 squared and 155kts true. Push
everything forward and we see 175 knots true at around 6000 ft and fuel
burns of 27 gallons per hour. Surprisingly close to book numbers for a
38
year old airplane.

So, at the high end of the power/fuel consumption curve you are gaining
20
kts TAS for only 3 gph? That's incredible! In my relatively efficient
Arrow I gain only about 6 kts TAS for about 2 GPH going from 65% to 75%
power. How do you do it?

--
-Elliott Drucker


27GPH-20GPH=7GPH
Huh!?! Are my eyes funny, or doesn't his original post reference *24* GPH
at 155 kts vs. 27 GPH at 175 kts?

inquiring minds...
Scott Skylane

You're right. I guess it is my eyes which are out of whack. They saw
20GPH which is the "short hop" number. Now the numbers make even less sense
since I would normally expect to see "short hop" fuel flow higher than the
"longer trip" fuel flow and he is also claiming a 13% increase in speed with
a 13% increase in fuel flow. I suspect that he uses the mxture lever on
some flights but not others

Mike
MU-2

You're right. I guess it is my eyes which are out of whack.

You're right. I guess my numbers are out of whack!
I ran though them from memory, which is normally good, but sometimes very
short.

They saw
20GPH which is the "short hop" number.

This is what we are seeing on 1 hour flights with only one take off and
landing. Multiple take offs and landings, then numbers get lower due to
more time at reduced power. We've actually seen numbers down around 16 for
pattern only work.

I looked up a round robin flight of 2.1 hours each way, power settings I
recorded were 24/24 and fuel tickets showed 90 gallons, so I had one too
many 24's in my head, that figures out to 21.4 gallons at 155 True.

Longer trips we've been flight planning at 25gph and it's hardly ever that
high at normal cruise settings. Speed runs at 175 kts burns 27.

So, I believe that we are getting a 13% increase in speed for a 26% increase
in fuel burn.

Thanks for makeing me look that up and correcting it. One problem we have
is the old fuel flow meters are wayyyyyyyy off towards the high side, which
I guess may be on the safe side.



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"Jim Burns" wrote in message
...

You're right. I guess it is my eyes which are out of whack.

You're right. I guess my numbers are out of whack!
I ran though them from memory, which is normally good, but sometimes very
short.

They saw
20GPH which is the "short hop" number.

This is what we are seeing on 1 hour flights with only one take off and
landing. Multiple take offs and landings, then numbers get lower due to
more time at reduced power. We've actually seen numbers down around 16
for
pattern only work.

I looked up a round robin flight of 2.1 hours each way, power settings I
recorded were 24/24 and fuel tickets showed 90 gallons, so I had one too
many 24's in my head, that figures out to 21.4 gallons at 155 True.

Longer trips we've been flight planning at 25gph and it's hardly ever that
high at normal cruise settings. Speed runs at 175 kts burns 27.

So, I believe that we are getting a 13% increase in speed for a 26%
increase
in fuel burn.

Thanks for makeing me look that up and correcting it. One problem we have
is the old fuel flow meters are wayyyyyyyy off towards the high side,
which
I guess may be on the safe side.


That is because the "fuel flow" guage in a Piper is really measuring fuel
pressure and displaying it in GPH. It is not a true fuel flow system. On
my Turbo Lance, I had a Shadin fuel flow system and it was dead accurate
while the stock guage always showed much higher numbers.

Mike
MU-2

Yep, you are exactly correct. I hope Santa cough's up a Shadin to interface
with our KLN94.

Jim

That is because the "fuel flow" guage in a Piper is really measuring fuel
pressure and displaying it in GPH. It is not a true fuel flow system.
On
my Turbo Lance, I had a Shadin fuel flow system and it was dead accurate
while the stock guage always showed much higher numbers.

Mike
MU-2




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Jim Burns wrote:

You're right. I guess it is my eyes which are out of whack.


You're right. I guess my numbers are out of whack!
I ran though them from memory, which is normally good, but sometimes very
short.


They saw
20GPH which is the "short hop" number.


This is what we are seeing on 1 hour flights with only one take off and
landing. Multiple take offs and landings, then numbers get lower due to
more time at reduced power. We've actually seen numbers down around 16 for
pattern only work.

I looked up a round robin flight of 2.1 hours each way, power settings I
recorded were 24/24 and fuel tickets showed 90 gallons, so I had one too
many 24's in my head, that figures out to 21.4 gallons at 155 True.

Longer trips we've been flight planning at 25gph and it's hardly ever that
high at normal cruise settings. Speed runs at 175 kts burns 27.

So, I believe that we are getting a 13% increase in speed for a 26% increase
in fuel burn.

That sounds much more reasonable ... and restores my faith in physics! :-)

Matt