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The following outline may be used as a guide to assist personnel in the use of the FLIGHT OPERATION INSTRUCTION CHART for flight planning purposes.

(a) If the fli9ht plan calls for a continuous flight where the desired cruising power and air speed are reasonably constant after take-off and climb to 5,000 feet, the fuel required and flight time may be computed as a "single section flight".

(1) Within the limits of the airplane, the fuel required and flying time for a given mission depends largely upon the speed desired. With all other factors remaining equal in the airplane) speed is obtained at a sacrifice of range) and range is obtained at a sacrifice of speed. The speed is usually determined after considering the urgency of the flight plotted against the range required. The time of take-off is adjusted so as to have the flight arrive at its destination at the predetermined time.

Fuel should be used in the following sequence:

I. Reserve tanks for first 15 minutes.

2. External tanks

3. Outer wing tanks (if installed).

4. Main tanks

5. Reserve tanks.

(2) Select the FLIGHT OPERATION INSTP~CTION CHART corresponding to the weight and external load items of the airplane. Locate the largest figure entered under gph (gallons per hour) in column 1 on the lower half of the chart. Multiply this figure by the number and/or fraction of hours desired for reserve fuel. Add the resulting figure to the number or gallons set forth in footnote No. 2., arid subtract the total from the amount of fuel in the airplane prior to starting the engines. The figure obtained as a result of this computation will represent the amount qf gasoline available and applicable for flight planning purposes on the "Range ii. Air Miles" section of the flight


(3) Select a figure in the fuel column equal to, or the next entry less than, the available amount of fuel in the airplane as determined in paragraph 2,a, (2) above. Move horizontally to the right or left and select a figure equal to, or the next entry greater than the air miles (with no wind) to be flown. Operating values contained in the column number in which this figure appears, represents the highest cruising speed possible at the range desired; however, the airplane may be operated in accordance with values contained under OPERATING DATA in any column of a higher number with the flight plan being completed at a sacrifice of speed but at an increase in fuel economy.

(4) Using the same column number selected by application of instruction contained in the preceding paragraphs, read the gallons per hour given at the altitude to be flown and divide this figure into the number of gallons available for cruising as determined in paragraph (2) above. This will give the calculated flight duration in hours, which can then be converted into hours and minutes and deducted from the desired arrival time at destination in order to obtain the take-off time (without consideration for wind). To allow for wind, determine the calculated ground speed by dividing the flight duration iii hours into the range selected in paragraph (3) and calculate a new corrected ground speed with the aid of a navigator's triangle of velocities.

This material is courtesy of Stan Wood WW2 P-38 Pilot in the Pacific.

More about Stan Wood and his P-38 experiances: Click Here