The Rutans and crew pretty thoroughl researched this maximum range

thing

and concluded (rightly) that low and slow was the best for range. I

know

this is contrary to common belief, but a close look at aircraft and

engine

characteristics will verify this. Vance

The range on my 182 goes up slightly with altitude as I recall. The

books with

the
range charts are up in the hangar. I'll check them out tomorrow. I

agree with

the slow part. There is an overall drag bucket where induced drag

drops off

and skin
and form drag starts to dominate.

Paul Lamar

Hi Vance,

How low would low be, 8,000 to 10,000 feet?

Doug

Unfortunately - low is less than 8000 feet, which does all sorts of nasty
things to your flight planning (Many of which happened to the Voyager)
things like nasty weather and limited power off gliding range. I admire
your goals, but I hope you have a realistic view of the challanges
involved - but without risk takers, we would still be huddled behind the
fire in the mouth of the cave - Vance

I suspect range increases with a turbo engine and with altitude although I
have
no evidence  to back it up yet.

Paul Lamar

Thanks Vance,

I suspect Voyager went low because of the nature of the engines and the
plane design.  I hope you know my trip will be a series of stops with the
longest leg in the north pacific.  The South Pacific would be nice but at
this point I don't know the fuel burn of the 20B turbo or without.
My brother usually flies very high in his turbo powered twin to get the best
gas mileage. Hmmmm.

With aggressive leaning at altitude (200 degrees F lean of peak) Tracy Crook 
is currently seeing .47 BSFC at moderate powers. That means if your airplane's 
drag bucket is 120 MPH then it will fly at that speed  at some very low power setting. 

Let us say that number is 40% of 200 HP or 80 HP.
You will burn 37.6 pounds per hours at a BSFC of .47 or about 6.3 gallons an hour. 
Your endurance  with 100 gallons of fuel will then be VERY roughly about 16 hours.
Multiply that by 120 MPH gives VERY roughly about 1900 miles.

The drag bucket MPH point is determined by max climb speed which changes
with gross weight. It is also the sink rate at zero power at a given gross weight. 
You can determine this by flight test ahead of time and keep a chart of max climb 
rate as a function of gross weight as your fuel burns off. Then you can slow down 
a bit as the flight progresses and extend the range slightly.

Do you know the best climb speed for the Sea Wind? You can also plot the drag
curve by recording the speed as a function of the power setting.

Here is a chart from Donald R. Crawford's book A Practical Guide to Airplane Performance
and Design. Lots of other stuff in there useful for calculating range.
 
I suspect a turbo 3 rotor will be slightly worse than .47 BSFC. My guess would be around
.5 BSFC. This too could be determined by flight test before hand.

Paul Lamar
 
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