SO...

Reading through an early 180 I’m looking at the cruise performance tables. It shows at a 20”/2200rpm cruise at 7500’ an ultimate range of about 775 miles on 55 gallons useable.

Does anyone actually get close to that?


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It shows at a 20”/2200rpm cruise at 7500’ an ultimate range of about 775 miles on 55 gallons usable.

The answer is no. I checked my C180A manual which gives the same information, but that information is not accurate. They didn't include a fuel reserve or the fuel needed to climb to altitude in their calculations. I can fly at a reduced power setting 17-18" 2200 RPM at 8-10 K burning around 10 gph. Cruise is around 125 KTAS with a O520 engine.

Realistically it would look like:

Time to climb to 8K - 100 knot climb for 12 minutes - 0.2 hours - 4-4.5 gallons = 20 nm
Cruise 125 KTAS X 4 hours at 10 GPH = 500 nm
Decent 130 KTAS at 0.3 hours at 10 GPH = 39 nm

4.5 hours of flight, 559 nm (642 sm), 47.5 gallons used.

I really hate legs longer than 3-3.5 hours due to the size of my bladder and the need to stretch the legs. I usually try to land with at least 10 gallons in the tank. You might be able to stretch the fuel a little further in that you have 29 usable gallons per side in level flight and I have filled 29 gallons in the left tank previously. It hasn't been too much of a problem for me since most of my legs are less than 500 nm.


Josh

Dog is my Copilot wrote:

It shows at a 20”/2200rpm cruise at 7500’ an ultimate range of about 775 miles on 55 gallons usable.

The answer is no. I checked my C180A manual which gives the same information, but that information is not accurate. They didn't include a fuel reserve or the fuel needed to climb to altitude in their calculations. I can fly at a reduced power setting 17-18" 2200 RPM at 8-10 K burning around 10 gph. Cruise is around 125 KTAS with a O520 engine.

Realistically it would look like:

Time to climb to 8K - 100 knot climb for 12 minutes - 0.2 hours - 4-4.5 gallons = 20 nm
Cruise 125 KTAS X 4 hours at 10 GPH = 500 nm
Decent 130 KTAS at 0.3 hours at 10 GPH = 39 nm

4.5 hours of flight, 559 nm (642 sm), 47.5 gallons used.

I really hate legs longer than 3-3.5 hours due to the size of my bladder and the need to stretch the legs. I usually try to land with at least 10 gallons in the tank. You might be able to stretch the fuel a little further in that you have 29 usable gallons per side in level flight and I have filled 29 gallons in the left tank previously. It hasn't been too much of a problem for me since most of my legs are less than 500 nm.


Josh

Thanks, hopefully hear from some O-470 folks too. You know us Alaskans, lots of places to pee, buy fuel, not so.


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Yes, the manual is very deceptive.
My 185 has the same issue. If you pick an altitude and look at the range chart is is simply the FF times the usable fuel. There is no accounting the climb fuel unless Cessna assumes the descent FF offsets the climb FF

For my 180A I planned 150mph/130kts at 12.5gph at 22"/2300rpm. This requires appropriate leaning. Easy to burn 2-4gph more than planned if you don't have EGT or fuel flow instruments.

55gal = 4.4hours

Choose your margin, subtract, multiply, account for wind.

I'm conservative with fuel so I can be a little less conservative elsewhere. I always plan to land with an hour of fuel in the tanks because plans change, weather drops, and passes close up.

With my 180B (O470-K) I plan 130-135knots at 12.5 gals/hr as well. I could go slower and burn less fuel, but for XC flights when you want to get somewhere, these are solid numbers.

The longest legs I like to fly are 3.5hrs or so. I'm conservative with fuel, and I usually am ready to stretch my legs at that point anyway, so it works out pretty well for me.

There's of course the extended range tanks option if you want more range.

asa wrote:For my 180A I planned 150mph/130kts at 12.5gph at 22"/2300rpm. This requires appropriate leaning. Easy to burn 2-4gph more than planned if you don't have EGT or fuel flow instruments.

55gal = 4.4hours

Choose your margin, subtract, multiply, account for wind.

I'm conservative with fuel so I can be a little less conservative elsewhere. I always plan to land with an hour of fuel in the tanks because plans change, weather drops, and passes close up.

I'm guessing you're running smaller tires?

akaviator wrote:

asa wrote:For my 180A I planned 150mph/130kts at 12.5gph at 22"/2300rpm. This requires appropriate leaning. Easy to burn 2-4gph more than planned if you don't have EGT or fuel flow instruments.

55gal = 4.4hours

Choose your margin, subtract, multiply, account for wind.

I'm conservative with fuel so I can be a little less conservative elsewhere. I always plan to land with an hour of fuel in the tanks because plans change, weather drops, and passes close up.

I'm guessing you're running smaller tires?

I don't own the plane anymore but that was Desser 850's and 88" C203 prop, O470K.

Thanks, that's pretty respectable speed!

1955 c180 with O470R:

I flight plan for 130kts and 12gals per hour. That gives an endurance of 4.5 hours and a range of 595 NM without reserves and a very quiet landing.

Flight settings at 8500’: 19”/2250rpm equals 10.5gals/hour in cruise with a graphic engine monitor and fuel flow gauge. With climb and landing it still averages to 12gals/hour.

Previous engine was the O470J and did slightly better but not enough to use different numbers.

Looking forward to pics and a report of your new plane!

CW

O-470R I’ll burn 16-18gph on climb out and get back to bout 11.5 or 12 at 130-135kts with the help of a JPI. I plan for 12.5gph on long trips.

Sounding like 130-135 kts and 12 gph is pretty realistic. Thanks guys.


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Yep - I have a 180E with O470R, and I run 8.50x6 tires (so still pretty speed efficient) - book numbers are 60 gallons usable - I set a personal min of 48 gallons usable. I average cruise about 125 knots burning 11.5 gph (at 2300/2100 63% power if I remember right) - so given fuel burn to climb and less for come down, I just use a nice round number of 4 hours for flight planning - could I stretch that - sure.. but I know that with 4 hours I have a nice safety margin if I hit some head winds - and it makes the math simple for me. My JPI 450 fuel flow is pretty spot on - so I always cross reference that with my time in the air to make sure everything is matching up - I pretty much ignore my fuel gauges - they are shit and only accurate when its empty.