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When I did those calculations I tried to be as conservative as possible to show minimal fuel consumption so we can determine range, especially for the P-39 but the charts from the flight manual speak for themselves. I wanted to show the source instead of flapping numbers without a mention of fuel consumption. As I was doing the calculations it became apparent that a mission to 25,000' was not the best profile for the P-39
Sorry, but my numbers are not wrong. I did use 16 gallons for warm up and climb instead of 20, I was looking at the P-39Q chart. So deduct 4 gallons if you want. You don't use both the 20gal reserve for warm up AND the fuel from sea level (31.2gal in your example) from the climb data chart. Just the warmup/takeoff/climb to 5000ft. Range includes climb but not descent. Since the pilot is climbing in the direction of the target at 170mph IAS he is effectively cruising at that speed until desired altitude is reached, about 10 minutes. The difference in climb speed and cruising speed for 10 minutes is negligible. Total fuel less allowance for warmup/takeoff/climb less combat reserve less landing reserve gives net fuel. Divide by gallons per hour to get cruising time and multiply by TAS (IAS converted) and that equals range. Everything is on the Flight Operation Instruction Chart you posted. I'm using the 120gal P-39.Several things - The P-39N manual I have shows best fuel consumption climb to 25K at 31.2 GPH at 30 minutes
View attachment 624415
Then there is no data for a 25K cruising altitude if that was your intention?? And nowhere do show GPH.
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And you didn't include the 20 gallons for warm up, you use 16 gallons reserve for the P-39 and 20 for the F4U, so I'm not going any further with the P-39
F4U
Way high cruising speed and fuel consumption. Greg beat me to the punch. Try around 200 MPH indicated at around 42 GHP at 5000' for the F4U's best cruise fuel consumption.
Sticking with your initial numbers (which are very wrong)
79 gal @ 42 GPH = 1.88 hrs in the air at 200 mph = 376 miles.
Please see my post #1503.I felt like doing some math...
So this is what I come up with, using those 2 charts posted and I used very conservative numbers except for take off weight, I used the fully loaded 8000 pounds, no wind condition to assume IAS will equal ground speed (for simplicity).
Start with 120 gallons (per the expert). Take away 20 gallons for warm up per the chart and you start with 100 gallons.
Take off at S/L, climb to 25,000 feet - 140 mph indicated, 31.2 gallons used, 29.9 minutes in the air at 140 mph so we traveled 70 miles.
68.8 gallons left.
In the cruise chart there is no data for 25,000' so we'll use 20,000'
Cruise 15 minutes, 160 MPH, 8.75 gallons used - 39 miles
60.1 gallons left.
Combat! 15 minutes. 10 minutes full power, 5 minutes WEP
34.75 gallons used. We'll also assume this was a traveling fight at 300mph - 75 miles
25.35 gallons left
Fight is over, descend down to 3000' (good cruising altitude) descend 1000' per minute at 160 mph 22 minutes, 12. 8 gallons used, 58 miles
12.6 gallons left.
10 gallons reserve, 2.55 gallons left. At 160 mph you'll burn that up in about 5 minutes, 40 miles
Total mission miles with 10 gallons reserve - 282 miles
I didn't account for blower setting, auto rich or lean or density altitude, just read the data straight off the charts. Also did not account for flying a pattern and landing. OK folks, check my math!
Please see my post #1503.At 7500 pounds - It now matches the 2nd chart
Start with 120 gallons (per the expert). Take away 20 gallons for warm up per the chart and you start with 100 gallons.
Take off at S/L, climb to 25,000 feet - 150 mph indicated, 35.3 gallons used, 10.8 minutes in the air at 150 mph so we traveled 27 miles.
64.7 gallons left.
In the cruise chart there is no data for 25,000' so we'll use 20,000'
Cruise 15 minutes, 160 MPH, 8.75 gallons used - 39 miles
55.95.1 gallons left.
Combat! 15 minutes. 10 minutes full power, 5 minutes WEP
34.75 gallons used. We'll also assume this was a traveling fight at 300mph - 75 miles
21.2 gallons left
Fight is over, descend down to 3000' (good cruising altitude) descend 1000' per minute at 160 mph 22 minutes, 12. 8 gallons used, 58 miles
8.4 gallons left.
About 5 minutes of fuel remaining - 13 miles
212 miles
Please see my post #1503.LET'S DO THE CORSAIR!!!
237 Gallons
Using max weight per the flight manual 14,200 pounds
Warm up and take off fuel consumption included per the flight manual chart.
Take off at S/L, climb to 25,000 feet - *125 knots indicated, 83 gallons used, 19 minutes in the air at *143.8 mph = 45 miles
159 Gallons left
Cruise 15 minutes, 14.5 gallons at *191mph ( *based on Report No. 6195 April 1, 1943 from Chance Vought. NAVAIR bases charts on endurance) = 47.7 miles
144.5 Gallons left
Combat! 15 minutes. 10 minutes full power, 5 minutes WEP 88 gallons at 380 mph = 94 miles NOTE: Military power used 275 GPH low blower per my manual (numbers were shown)
56.5 Gallons left
Fight is over, descend down to 3000' (good cruising altitude) descend 1000' per minute at 191 mph 22 minutes, 15.9 gallons used, 70 miles
40.6 Gallons left
Minus 10 gallons reserve -
30.6 Gallons left
40 minutes left in the air at 191 mph = 127 miles
384 miles
View attachment 624443
View attachment 624444
I said cruising back at 1500ft, not 15000ft.In Post 1503, you say cruising out and returning at 15,000 feet would be suicidal. That's EXACTLY why USN and USAAF airplanes are different ... they have differing requirements and different missions. So, there is no real point in comparing them for missions since they do different things. Hence, two different services.
You made the point perfectly. Navy/Marine and Air Corps airplanes were not going to do the same missions very often, so there is no point in comparing the two.
So don't. Compare instead against aircraft that would be flying the same missions.
WRONG - read the chart!!!!Sorry, but my numbers are not wrong. I did use 16 gallons for warm up and climb instead of 20, I was looking at the P-39Q chart. So deduct 4 gallons if you want. You don't use both the 20gal reserve for warm up AND the fuel from sea level (31.2gal in your example) from the climb data chart.
Just the warmup/takeoff/climb to 5000ft. Range includes climb but not descent.
Since the pilot is climbing in the direction of the target at 170mph IAS he is effectively cruising at that speed until desired altitude is reached, about 10 minutes.
WHERE DOES IT SAY TO DO THAT?!?The difference in climb speed and cruising speed for 10 minutes is negligible. Total fuel less allowance for warmup/takeoff/climb less combat reserve less landing reserve gives net fuel.
Divide by gallons per hour to get cruising time and multiply by TAS (IAS converted) and that equals range. Everything is on the Flight Operation Instruction Chart you posted. I'm using the 120gal P-39.
If the P-39 and the F4U are used for the same mission then they have to use the same formula and mission profile.
Takeoff and climb to 25000ft, cruise at maximum cruise, 20 minutes of combat and cruise back at maximum cruise with a 20 minute reserve for landing. The Navy used a cruise out at 15000ft at V max for max range (182mph) and then cruise back at 1500ft at V max range. That works fine for over water flights where the chance of encountering the enemy is small, but that won't work at all for escort or interception missions over land as the AAF did. Cruising out at 15000ft or cruising back at 1500ft would be suicidal.
Takeoff and climb to 25000ft, cruise at maximum cruise, 20 minutes of combat and cruise back at maximum cruise with a 20 minute reserve for landing.
Is that because there was no other cruise setting that worked at 25,000ft?
You don't use both the 20gal reserve for warm up AND the fuel from sea level (31.2gal in your example) from the climb data chart. Just the warmup/takeoff/climb to 5000ft.
From our resident fighter pilot, thank you Biff!Interesting. Also remember you are doing a single ship. Add more aircraft, use more fuel for ground ops, takeoff, and rejoin. The more you add, the more fuel you use, and the shorter the range.