New (old) bird

One could always fly slower to get the fuel burn closer to a 4-pax
airplane, but does anyone every really do this?

I always *say* I can do this, with our 6-cylinder O-540, and technically I
can. Shoot, I can lean it all the way back to 8 gph, and fly at C-150
speeds.

Do I? Hell, no! I cruise at 140 knots, at 15 gph. The only time I
throttle back to 10 gph is when I'm flying with friends in their 172s or
Warriors as a flight of 2 or 3. The rest of the time, I like to go
faster -- even though it makes little sense to do so.

Human nature, I guess. Or, just plain dumb...

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck wrote:


Do I? Hell, no! I cruise at 140 knots, at 15 gph.


Ouch.

Newps wrote:


Jay Honeck wrote:


Do I? Hell, no! I cruise at 140 knots, at 15 gph.



Ouch.

Jay, I thought book cruise fuel burn for a 235 was about 12 GPH. Why
are you burning 15? Book for my Six is 14 GPH, and I would be getting
that if I wasn't fighting the front two cylinders running so lean with
WOT. Sounds to me like a move up to a Six wouldn't be as painful as you
made it out to be the other day. So are we going to see you show up at
OSH in a six this year then?

Sure. I'll pick him up on my way... :-D

"Ray Andraka" wrote in message
...
Newps wrote:


Jay Honeck wrote:


Do I? Hell, no! I cruise at 140 knots, at 15 gph.



Ouch.

Jay, I thought book cruise fuel burn for a 235 was about 12 GPH. Why
are you burning 15? Book for my Six is 14 GPH, and I would be getting
that if I wasn't fighting the front two cylinders running so lean with
WOT. Sounds to me like a move up to a Six wouldn't be as painful as you
made it out to be the other day. So are we going to see you show up at
OSH in a six this year then?

Ray Andraka wrote:
Newps wrote:


Jay Honeck wrote:


Do I? Hell, no! I cruise at 140 knots, at 15 gph.



Ouch.

Jay, I thought book cruise fuel burn for a 235 was about 12 GPH. Why
are you burning 15? Book for my Six is 14 GPH, and I would be getting
that if I wasn't fighting the front two cylinders running so lean with
WOT. Sounds to me like a move up to a Six wouldn't be as painful as you
made it out to be the other day. So are we going to see you show up at
OSH in a six this year then?



Running 15 gph for a 235 hp engine is a colossal waste of gas at cruise
speed. My 285 hp engine(IO-520) gets 75% at 14 gph.

Newps wrote:



Ray Andraka wrote:

Newps wrote:



Jay Honeck wrote:


Do I? Hell, no! I cruise at 140 knots, at 15 gph.




Ouch.


Jay, I thought book cruise fuel burn for a 235 was about 12 GPH. Why
are you burning 15? Book for my Six is 14 GPH, and I would be getting
that if I wasn't fighting the front two cylinders running so lean with
WOT. Sounds to me like a move up to a Six wouldn't be as painful as
you made it out to be the other day. So are we going to see you show
up at OSH in a six this year then?




Running 15 gph for a 235 hp engine is a colossal waste of gas at cruise
speed. My 285 hp engine(IO-520) gets 75% at 14 gph.

Book burn for my 260 hp O-540 is 14 gph. Both mine and Jay's are
carbureted, so we end up with a wider spread between cylinders, which in
turn means we lean to the leanest cylinder and accept the fuel burns of
the others. I've currently got an issue I am trying to track down with
mine that is making the front two cylinders reach peak EGT some 270-300
degrees before the others, which in turn is making my fuel burn close to
19gph (no, it isn't an induction leak, we've pressurized the intake and
checked it, plus the problem is most noticible at WOT on cold days. If
it were an intake leak, it would be accentuated at lower throttle
settings rather than higher ones). Previously, I used to get EGT
spreads around 150 deg and was getting fuel burns pretty close to the
14gph book value. I don't know why Jay is burning 25% more than book,
and am curious if he knows why (or maybe it was a typo?).

Previously, I used to get EGT spreads around 150 deg and was getting fuel
burns pretty close to the 14gph book value. I don't know why Jay is
burning 25% more than book, and am curious if he knows why (or maybe it
was a typo?).

We normally fly at 23 squared, and lean back in order to keep EGTs within
100 degrees of each other, and under 1600 degrees. We try to keep CHTs
under 350 degrees. We usually cruise between 3500 and 6500 feet. At 3500
feet our FS-450 will indicate 15 gph at these settings.

At 6500 feet it will be closer to 14 gph.

Way back when, we calibrated the FS-450 to read "fat", in order to err on
the side of high fuel burn. I'd bet it's off by close to 1 gph, so we're
probably flying closer to 14 and 13 gph.

Can we lean back further? Sure.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck wrote:
One could always fly slower to get the fuel burn closer to a 4-pax
airplane, but does anyone every really do this?

I always *say* I can do this, with our 6-cylinder O-540, and technically
I can. Shoot, I can lean it all the way back to 8 gph, and fly at C-150
speeds.

Do I? Hell, no! I cruise at 140 knots, at 15 gph.

Lean, grasshopper, lean!

Matt

Do I? Hell, no! I cruise at 140 knots, at 15 gph.

Lean, grasshopper, lean!

Snort! That *is* leaned. At take-off, we'll be around 24+ gph...

:-)

I read about these LSAs flying around at 120 knots on 3 gph, and start
salivating.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

When operating properly in cruise lean of peak 14.9 times fuel flow
equals horsepower. So pick your desired percent HP and set the fuel
flow accordingly.
When ROP, HP is proportional to AIR (controlled by RPM and MP), and
changing the FF doesn't matter much.





Jay Honeck wrote:
Do I? Hell, no! I cruise at 140 knots, at 15 gph.

Lean, grasshopper, lean!

Snort! That *is* leaned. At take-off, we'll be around 24+ gph...

:-)

I read about these LSAs flying around at 120 knots on 3 gph, and start
salivating.