1960 cessna POH climb data

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deaston

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Dan
Newly minted pilot here (passed the check ride last weekend - :D). I'm trying to decipher the performance data from the POH for a 1960 Cessna 172a that I'm flying.

On that page 6-2, it shows a table for climb data (I'd post a PDF of it as an attachment if I could). In that table is a column labeled "Gal. of Fuel Used". I don't understand what this means. It certainly isn't GPH, because the numbers are like 2.1, 1.8, etc. The only footnotes are the it is in clean, leaned configuration, and that it includes warm-up and takeoff allowance.

Can anyone explain?

Thx

EDIT: Figured out how to share this so you can see for yourself. Page 6-2 of the manual (page 30 of pdf).
1960 Cessna 172a POH
 
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Is the table "Time, Fuel, and Distance to Climb"? If so those numbers are plain old gallons. Note at the top "Add 1.1 gallons of fuel for engine start, taxi, and takeoff allowance"? These are quotes from a 1977 172N.

Bob Gardner
 
Thanks for the response Bob. I just figured out how to share the PDF, so if you are willing to check out, I edited my first post. I think this is a different format that the newer tables you are referring to.
 
deaston said:
Newly minted pilot here (passed the check ride last weekend - :D). I'm trying to decipher the performance data from the POH for a 1960 Cessna 172a that I'm flying.

On that page 6-2, it shows a table for climb data (I'd post a PDF of it as an attachment if I could). In that table is a column labeled "Gal. of Fuel Used". I don't understand what this means. It certainly isn't GPH, because the numbers are like 2.1, 1.8, etc. The only footnotes are the it is in clean, leaned configuration, and that it includes warm-up and takeoff allowance.

Can anyone explain?

Thx

EDIT: Figured out how to share this so you can see for yourself. Page 6-2 of the manual (page 30 of pdf).
1960 Cessna 172a POH
Click to expand...

That data is how much fuel you'd use to climb from sea level to the altitude on the chart (I think the first column is just for the takeoff and no climb). It looks like they expect you to interpolate for cruise altitudes not shown. If you do your flight planning precisely and by hand, you'd take the difference between the fuel used to get to your starting altitude (field elevation) and the fuel used to reach your cruising altitude and add it to the fuel required for taxi, takeoff, cruise, and landing. But most pilots I know don't bother with that level of detail. An decent alternative rule of thumb is to take the weight of the airplane in pounds divided by 10000. Multiply this by the thousands of feet of altitude gained during the climb to get the additional amount needed for the takeoff and climb. Add that to the amount needed if you flew the entire distance at cruise altitude to get the total required. This is double the theoretical requirement based on 100 % efficiency and ignores the energy gained during descent but it has worked pretty well for any piston engined airplane I've flown.

For example if your 2200 lb 172 burns 6 gph in cruise at 9000 MSL on a 200 nm trip with a 100 Kt ground speed, after taking off from an airport at 1000 MSL, figure the total fuel as:

Takeoff and climb fuel = (9000-1000)/10,000 * 2.2 = 0.8 * 2.2 = 1.8 gal
Cruise fuel (if at 9000 the whole way) = 200/100 * 6 = 12 gal
Total fuel consumed on the flight = 12+1.8 = 13.8 gal.
 
Gallons of fuel burned in the climb from takeoff to cruise alt. (assuming takeoff at SL)
 
Hi Dan. Welcome to POA.

Our C-150 has tables similar to those you posted. It is gallons of fuel used from SL to the altitude listed, then you also use the next columns for climbing on up. I have checked our C-150 (1966 model) and the tables, if used correctly, very accurately reflect fuel burn. Pretty neat when you calculate how much fuel should be used, then pull up to the pump and the amount of fuel you add matches (or very nearly so). In actual practice, just be sure to lean so you aren't putting unburned fuel out the exhaust.
 
Thanks for the replies. I think I get it now and it makes sense. The key was knowing this was total fuel consumed to climb from sea level to the various altitudes. I had never seen it written like this, and most of the flight planning tools want climbing fuel consumption rate. Now that I get it, I think I can estimate the rate.

One other question. The temperature at each altitude seems to be standard (59 degF @ SL; 41 degF @ 5,000'; 23 degF @ 10,000') until it gets to 15,000, where it jumps to 50 degF. Is there a practical reason to choose that temperature for this table? Just curious...
 
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