Single-engine plane with the best range?

Using a 172P POH as an example, at 8000 feet density altitude and 75
percent, the range is eyeballed as 575 nm; at 65 percent it is 640; at 55
percent it is 680, all based on 50 gallons available with reserve. With 62
gallons available (with reserve), the numbers a 75 percent 755 nm, at 65
percent 820, and at 55 percent 870. Sure looks to me as though reducing the
power setting increases range, as does carrying more fuel.

Bob Gardner

"Stealth Pilot" wrote in message
...
On Mon, 16 Feb 2004 20:59:55 GMT, "Bob Gardner"
wrote:

The range for any aircraft is dependent on power setting (and fuel
available, of course). If speed is not important, you could operate at
50-percent of max power and get astounding range...but few pilots are
willing to make that tradeoff.

Bob Gardner


bob my experience doesnt support that.

I fly a Wittman W8 tailwind with an O-200.

flying between Ceduna and Forrest via Nullabor Homestead is about 297
nautical miles.
I have made the flight with two settings.
-at reduced rpm (about 1800rpm) and about 70 knots. (in company with a
piper cub)
-at cruise rpm (2500 rpm) and 114 knots.
weight and aircraft trim was just about the same.

believe it or not the fuel consumed was the same.

reducing your rpm gets you more time aloft but does not increase your
range.
it seems to take the same amount of energy to move the aircraft the
distance. all you vary with rpm is the rate of energy conversion and
the air speed.

another point pertinent to the original posters question.

the fuel bill for a thorp T18 with an O-360 engine and a W8 Tailwind
with an O-200 engine is about the same for the flight across
australia.
the thorp cruises around 180 knots and does the trip in 1 day. I
cruise at 114 knots and it takes 2 days.
it astounds me that the fuel consumed is about the same.

of course these flights are made upside down (downunder) and our
Lycoming and Continental engines might be different from yours.
...and these are both taildraggers. :-)
ymmv
Stealth Pilot
Australia.

On Wed, 18 Feb 2004 19:09:35 GMT, "Bob Gardner"
wrote:

Using a 172P POH as an example, at 8000 feet density altitude and 75
percent, the range is eyeballed as 575 nm; at 65 percent it is 640; at 55
percent it is 680, all based on 50 gallons available with reserve. With 62
gallons available (with reserve), the numbers a 75 percent 755 nm, at 65
percent 820, and at 55 percent 870. Sure looks to me as though reducing the
power setting increases range, as does carrying more fuel.

Bob Gardner


I suppose the lesson here is that compensating factors for SOME
aircraft can negate the theoretical advantages for different settings.

The engine in my case was leaned to peak rpm in both cases.

for the guy who asked the original question. doing your research
certainly pays.

Stealth Pilot
Australia.

"Stealth Pilot" wrote in message
news
I suppose the lesson here is that compensating factors for SOME
aircraft can negate the theoretical advantages for different settings.

"Compensating factors"? Such as, for example?

In your particular case, I can well believe that you found the same fuel
consumption at 114 knots as at 70 knots. However, that simply means that
you selected the wrong airspeed for best range. Your airplane is not immune
to the laws of physics.

Pete

On Sat, 21 Feb 2004 10:59:25 -0800, "Peter Duniho"
wrote:

"Stealth Pilot" wrote in message
news
I suppose the lesson here is that compensating factors for SOME
aircraft can negate the theoretical advantages for different settings.

"Compensating factors"? Such as, for example?

In your particular case, I can well believe that you found the same fuel
consumption at 114 knots as at 70 knots. However, that simply means that
you selected the wrong airspeed for best range. Your airplane is not immune
to the laws of physics.

Pete

never hinted that it was immune from anything. it is just a Wittman W8
Tailwind. in my case pete the engine firewall forward is a standard
cessna 150 installation. it behaves a litte differently from a cessna
150.

the overall performance of an aircraft is the result of the
performance of a lot of its component systems. selecting one in
isolation wont necessarily give you a clue as to the final figures for
the overall aircraft.

btw I wasnt making any attempt at best range. I was merely flying
across 300 miles of desert with a chap in a piper cub for moral
support. you do assume a lot in some of your comments.

now instead of leaping down my throat can you give the guy who asked
the original question some assistance in selecting a suitable
aircraft?

Stealth Pilot
Australia

"Stealth Pilot" wrote in message
...
never hinted that it was immune from anything.

True, you didn't hint at it. You just came right out and claimed it. Bob
wrote "the range for any aircraft is dependent on power setting", and you
wrote "my experience doesnt [sic] support that". When in fact the range for
any aircraft IS dependent on power setting.

Bob's statement was somewhat inaccurate in that 50% power may or may not
produce best range, and may not even be better range than normal cruise.
But it's impossible that your experience would contradict that the range is
dependent on power setting, because range DOES depend on power setting.

[...]
the overall performance of an aircraft is the result of the
performance of a lot of its component systems. selecting one in
isolation wont necessarily give you a clue as to the final figures for
the overall aircraft.

The basic aerodynamic characteristic -- namely, the fact that there's a
L/Dmax, and that flying slower or faster than that speed causes an increase
in drag -- is immutable. The specifics may indeed change based on "the
performance of a lot of its component systems", but the fact will always
remain that there will always been a speed at which the least drag occurs,
and that flying above or below that speed will result in more fuel consumed
for the same distance.

btw I wasnt making any attempt at best range. I was merely flying
across 300 miles of desert with a chap in a piper cub for moral
support. you do assume a lot in some of your comments.

Such as? All I have done is disagree with statements that YOU MADE. I made
no assumptions, I took your false statements at face value and explained why
they MUST be false. I never said that you were making an attempt at best
range. What I said was that your experience could not have contradicted the
FACT that range depends on power setting.

now instead of leaping down my throat can you give the guy who asked
the original question some assistance in selecting a suitable
aircraft?

His question is far too broad for any answer to be useful. I tried to make
a sensible reply when his first post showed up, and found that there was not
enough information in his original question to provide any concise answer.
I doubt he was looking for the three-page reply it would have required, nor
did I have any interest in spending that much time writing such a reply.

IMHO, he has been provided plenty of *accurate* information in this
thread -- your own posts notwithstanding -- to inform him regarding the
issues specific to range, and a few different types of aircraft that might
suit his needs. His budget is going to be the limiting factor in any case,
and with only $40K to spend, none of the aircraft he might consider is going
to go all that far with one fillup.

Pete

On Sun, 22 Feb 2004 12:19:52 -0800, "Peter Duniho"
wrote:

"Stealth Pilot" wrote in message
.. .
never hinted that it was immune from anything.

True, you didn't hint at it. You just came right out and claimed it. Bob
wrote "the range for any aircraft is dependent on power setting", and you
wrote "my experience doesnt [sic] support that". When in fact the range for
any aircraft IS dependent on power setting.

Bob's statement was somewhat inaccurate in that 50% power may or may not
produce best range, and may not even be better range than normal cruise.
But it's impossible that your experience would contradict that the range is
dependent on power setting, because range DOES depend on power setting.


peter
the time, the duration, that an aircraft can remain airborne is
dependent on power setting. not necessarily the range achieved.

what I posted were some factual observations. dispute them if you
will, they still remain what I observed.
ymmv
Stealth Pilot
Australia

"Stealth Pilot" wrote in message
...
the time, the duration, that an aircraft can remain airborne is
dependent on power setting. not necessarily the range achieved.

It affects both.

what I posted were some factual observations. dispute them if you
will, they still remain what I observed.

I'm not disputing your observations. I'm disputing that they have any
bearing at the question in hand, and in particular, your claim that they
somehow disprove the fact that for any airplane, an increase in range can be
had by reducing the power setting below the normal cruise setting.

Pete