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B-24 (Usually D model) performance
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Geoffrey Sinclair
Aug 30, 2015, 3:27:50 PM8/30/15
to
Since I ended up with the notes out while looking for bomb
loads.
Airspeeds are true, not indicated unless noted.
Shackles in the B-24 for all bombs up to 1,600 pounds weighed 3
pounds, the 2,000 pound bomb required a 44 pound shackle,
nominal/actual weights for the bombs were 100/117, 300/306,
500/486, 1,000/966, 1,600/1,600, 2,000/2,050 pounds. A pair
of 0.50 inch guns and mountings came in at 150 to 160 pounds,
100 rounds of ammunition at 30 pounds. The ball turret without
guns came to 787 pounds, the nose turret without guns 482
pounds. A US gallon of 100 octane was 5.84 pounds at
standard temperature.
The B-24 used 75 gallons for warm up and take off, at 35,000
pounds initial weight it was another 40 to 42 gallons to make
it to 8,000 feet, at 65,000 pounds initial weight around 165 to
170 gallons using narrow blade propellers, using wide blade
it was 40 and around 125 gallons respectively. Apart from
pulling up the extra weight you needed to fly faster to generate
the required lift, 130 versus 162 mph indicated air speed.
Using the wide blade propellers it was about 120 gallons at
35,000 pounds to climb to 24,000 feet, at 65,000 pounds
around 470 gallons.
Best fuel economy, ignoring the cost of the climb, warm up and
leaving no reserves, gave a theoretical range of 6,100 miles at
165 mph true air speed at 1,000 feet, 6,250 miles at 171 mph
at 5,000 feet, 6,275 miles at 182 mph 10,000 feet, 6,300 miles
at 193 mph at 15,000 feet, 6,150 miles at 20,000 feet (speeds
not given on the chart for 20,000 feet or higher), 5,950 miles at
25,000 feet, 5,750 miles at 30,000 feet. So if you are flying at
higher speeds altitude is good, at 30,000 feet at 260 mph
theoretical range is 5,150 miles, at 280 mph 3,650 miles, at
1,000 feet at 231 to 241 mph theoretical range is 2,125 miles.
By the way the above are density altitudes, the real altitude
corrected for air temperature and of course the fuel cost to
make higher altitudes is significant.
Fuel consumption on the B-24 rises with altitude, Military power
used 630 gallons per hour at sea level, 2,700 RPM, rich mixture
and 670 gallons per hour at 26,500 feet when the turbo
supercharger limit cut in, 100% power was 575 gallons per hour
at sea level, 2,550 RPM rich mixture, to 595 gallons at the turbo
limit altitude of 26,500 feet. 65% power at 2,200 RPM rich
mixture used 305 gallons per hour at sea level and 320 at
30,000 feet, using lean mixture the consumption figures are 250
and 265 respectively. At 55% power or lower RPM had to be
increased at 25,000 feet with an accompanying increase in fuel
consumption.
The time to climb chart notes 26,500 feet was the turbo
supercharger limit, above which engine power had to be controlled
to avoid overloading the supercharger. With narrow blade propellers
the time to climb to 26,500 feet was 15.5 minutes with a take off
weight of 35,000 pounds, 18 minutes at 40,000 pounds, 21 minutes
at 45,000 pounds, 26 minutes at 50,000 pounds, 34.5 minutes at
55,000 pounds, 50.5 minutes at 60,000 pounds and at a take off
weight of 65,000 pounds the B-24D was just approaching 20,000
feet after 56 minutes. Wide blade propellers made the times to
26,500 feet 14, 16, 19, 22.5, 25.5, 36 and 52.5 minutes.
Put all the above together and you can see the B-24 in Europe, fast
climb to around or over 20,000 feet, tight formation, fast cruise to
target, had a much lower effective range than in the Pacific, slow
climb, loose formation at low cruise speed to target, with 20,000
feet an unusually high altitude as far as I am aware.
The Gross Weight Nomogram page for the B-24D has the following
carefully spaced vertical graph lines across the page, from left to right,
payload or bombs and ammunition weight, 0 to 10,000 pounds,
vertical X point reference line (see below), number of crew and
passengers from 0 to 35, gross weight from 35,100 to 67,000 pounds,
fuel load 0 to over 3,000 imperial, 0 to over 3,500 US gallons, vertical
Y point reference line, oil load 0 to 200 imperial or 0 to 240 US gallons.
Draw a straight line between the fuel and oil lines using the amounts
you are carrying, where it crosses the Y line is point Y, draw another
straight line between the payload and crew size being carried, where
it crosses the X line is point X, draw a straight line between X and Y,
where it crosses the weight line tells you the aircraft take off weight.
The USN reports its B-24 (PB4Y-1) carrying 8x0.50 inch guns with
3,770 rounds at 63,000 pounds take off weight had the following
performance,
3,063 gallons of fuel (including 400 in a bomb bay tank) 156 gallons
of oil, 2x500 pound bombs, 3,260 miles at 148 mph at 1,500 feet,
2,019 gallons of fuel, 112 gallons of oil, 8x1,000 pound bombs,
2,065 miles at 154 mph at 1,500 feet
1,272 gallons of fuel, 70 gallons of oil, 8x1,600 pound bombs,
1,255 miles at 155 mph at 1,500 feet
The range chart versus speed for the 2,019 gallons of fuel option is
a gentle curve dropping to around 1,625 miles at 190 mph, then a
vertical drop to 1,250 miles at the same speed then a near straight
line to 700 miles at 225 mph.
The range chart versus speed for the 1,272 gallons of fuel option
has the same pattern, down to 1,000 miles at 190 mph, the drop to
750 miles at the same speed then the linear decline to 450 miles at
225 mph. However at 10,000 feet range is less than at 1,500 feet
until 170 mph where the two curves meet at 1,200 miles, at 10,000
feet the vertical drop is at 205 mph, from 1,100 to 800 miles, then
another curve, declining to 475 miles at 243 mph.
USN Range: Maximum range and range versus speed curves
assume no fuel used during warm-up or take-off and no fuel
allowed for reserve. The effect on fuel consumption resulting from
climb (at normal rated power, auto rich) to designated altitude
and descent has been included. Range calculations based in
tests or specification data have been found to be optimistic,
accordingly, all rates of specific fuel consumption have been
suitably increased. Where engine requirement data are used,
they are increased 15%; where flight test data are used, they
are increased by 5%. For jet propulsion one-half of these
percentages are used. Bombs, torpedoes, all droppable tanks
and radar are carried the full distance.
The above B-24 USN ranges use the 5% correction factor.
For some comparison.
RAF Range: Non fighter types, deduct the fuel used in 20
minutes at maximum economic cruise (for warm up, taxying,
take off and climb), deduct a further 30 minutes at maximum
economic cruise to allow for time over target, navigational
errors and emergencies. So no allowance for wind, formation
flying or full throttle use. Fighter types, deduct fuel used in 15
minutes at maximum power at sea level (for warm up, taxying,
take off and climb), range is then at maximum economic cruise
on the remaining fuel.
Spitfire I, normal weight 6,255 pounds, 415 miles at 304 mph
at 15,000 feet, 1.4 hours endurance, 575 miles at 180 to 190
mph at 15,000 feet, 3.1 hours endurance, 87 octane fuel, 484
pounds available for cruise out of 630 pounds or 84 gallons carried.
Spitfire II, normal weight 6,238 pounds, 335 miles at 304 mph
at 15,000 feet, 1.07 hours endurance, 530 miles at 180 to 190
mph at 15,000 feet, 2.86 hours endurance, 100 octane fuel, 414
pounds available for cruise out of 605 pounds or 84 gallons carried.
Spitfire V, normal weight 6,460 pounds, 335 miles at 310 mph at
15,000 feet, 1.08 hours endurance, 480 miles at 180 to 190 mph
at 15,000 feet,100 octane fuel, 389 pounds available for cruise
out of 630 pounds or 84 gallons carried.
The mark I and II carried 8x0.303 inch with a total of 2,800 rounds,
the mark V 2x30mm with a total of 120 rounds, and 2x0.303 inch
with a total of 1,400 rounds.
Wellington Ic, 6x0.303 inch guns, 7,000 rounds of ammunition,
take off weight 30,000 pounds, 25 minutes to 10,000 feet, 87
octane fuel, 518 pounds of fuel deducted from total for 50 minute
allowance. Permanent fuel tankage is 750 gallons, auxiliary tank
280 gallons.
Cruise at 195 mph at 10,000 feet,
4,500 pounds of bombs, total fuel 518 gallons = 3,888 pounds,
range 1,055 miles, endurance 5.4 hours.
2,800 pounds of bombs, total fuel 750 gallons = 5,620 pounds,
range 1,600 miles, endurance 8.2 hours.
500 pounds of bombs, total fuel 1,030 gallons = 7,720 pounds,
range 2,255 miles, endurance 11.55 hours.
Cruise at 165 mph at 10,000 feet,
2,800 pounds of bombs, total fuel 750 gallons = 5,620 pounds,
range 1,805 miles, endurance 10.95 hours.
500 pounds of bombs, total fuel 1,030 gallons = 7,720 pounds,
range 2,550 miles, endurance 15.5 hours.
Essentially aircraft performance is a series of graphs, a single
set of figures needs a lot of explanatory notes if you are being
really exact. Different air forces had different measurement
criteria which helps explain why, over and above individual
variability, tests of the same aircraft type could have different
results.
Geoffrey Sinclair
Remove the nb for email.
loads.
Airspeeds are true, not indicated unless noted.
Shackles in the B-24 for all bombs up to 1,600 pounds weighed 3
pounds, the 2,000 pound bomb required a 44 pound shackle,
nominal/actual weights for the bombs were 100/117, 300/306,
500/486, 1,000/966, 1,600/1,600, 2,000/2,050 pounds. A pair
of 0.50 inch guns and mountings came in at 150 to 160 pounds,
100 rounds of ammunition at 30 pounds. The ball turret without
guns came to 787 pounds, the nose turret without guns 482
pounds. A US gallon of 100 octane was 5.84 pounds at
standard temperature.
The B-24 used 75 gallons for warm up and take off, at 35,000
pounds initial weight it was another 40 to 42 gallons to make
it to 8,000 feet, at 65,000 pounds initial weight around 165 to
170 gallons using narrow blade propellers, using wide blade
it was 40 and around 125 gallons respectively. Apart from
pulling up the extra weight you needed to fly faster to generate
the required lift, 130 versus 162 mph indicated air speed.
Using the wide blade propellers it was about 120 gallons at
35,000 pounds to climb to 24,000 feet, at 65,000 pounds
around 470 gallons.
Best fuel economy, ignoring the cost of the climb, warm up and
leaving no reserves, gave a theoretical range of 6,100 miles at
165 mph true air speed at 1,000 feet, 6,250 miles at 171 mph
at 5,000 feet, 6,275 miles at 182 mph 10,000 feet, 6,300 miles
at 193 mph at 15,000 feet, 6,150 miles at 20,000 feet (speeds
not given on the chart for 20,000 feet or higher), 5,950 miles at
25,000 feet, 5,750 miles at 30,000 feet. So if you are flying at
higher speeds altitude is good, at 30,000 feet at 260 mph
theoretical range is 5,150 miles, at 280 mph 3,650 miles, at
1,000 feet at 231 to 241 mph theoretical range is 2,125 miles.
By the way the above are density altitudes, the real altitude
corrected for air temperature and of course the fuel cost to
make higher altitudes is significant.
Fuel consumption on the B-24 rises with altitude, Military power
used 630 gallons per hour at sea level, 2,700 RPM, rich mixture
and 670 gallons per hour at 26,500 feet when the turbo
supercharger limit cut in, 100% power was 575 gallons per hour
at sea level, 2,550 RPM rich mixture, to 595 gallons at the turbo
limit altitude of 26,500 feet. 65% power at 2,200 RPM rich
mixture used 305 gallons per hour at sea level and 320 at
30,000 feet, using lean mixture the consumption figures are 250
and 265 respectively. At 55% power or lower RPM had to be
increased at 25,000 feet with an accompanying increase in fuel
consumption.
The time to climb chart notes 26,500 feet was the turbo
supercharger limit, above which engine power had to be controlled
to avoid overloading the supercharger. With narrow blade propellers
the time to climb to 26,500 feet was 15.5 minutes with a take off
weight of 35,000 pounds, 18 minutes at 40,000 pounds, 21 minutes
at 45,000 pounds, 26 minutes at 50,000 pounds, 34.5 minutes at
55,000 pounds, 50.5 minutes at 60,000 pounds and at a take off
weight of 65,000 pounds the B-24D was just approaching 20,000
feet after 56 minutes. Wide blade propellers made the times to
26,500 feet 14, 16, 19, 22.5, 25.5, 36 and 52.5 minutes.
Put all the above together and you can see the B-24 in Europe, fast
climb to around or over 20,000 feet, tight formation, fast cruise to
target, had a much lower effective range than in the Pacific, slow
climb, loose formation at low cruise speed to target, with 20,000
feet an unusually high altitude as far as I am aware.
The Gross Weight Nomogram page for the B-24D has the following
carefully spaced vertical graph lines across the page, from left to right,
payload or bombs and ammunition weight, 0 to 10,000 pounds,
vertical X point reference line (see below), number of crew and
passengers from 0 to 35, gross weight from 35,100 to 67,000 pounds,
fuel load 0 to over 3,000 imperial, 0 to over 3,500 US gallons, vertical
Y point reference line, oil load 0 to 200 imperial or 0 to 240 US gallons.
Draw a straight line between the fuel and oil lines using the amounts
you are carrying, where it crosses the Y line is point Y, draw another
straight line between the payload and crew size being carried, where
it crosses the X line is point X, draw a straight line between X and Y,
where it crosses the weight line tells you the aircraft take off weight.
The USN reports its B-24 (PB4Y-1) carrying 8x0.50 inch guns with
3,770 rounds at 63,000 pounds take off weight had the following
performance,
3,063 gallons of fuel (including 400 in a bomb bay tank) 156 gallons
of oil, 2x500 pound bombs, 3,260 miles at 148 mph at 1,500 feet,
2,019 gallons of fuel, 112 gallons of oil, 8x1,000 pound bombs,
2,065 miles at 154 mph at 1,500 feet
1,272 gallons of fuel, 70 gallons of oil, 8x1,600 pound bombs,
1,255 miles at 155 mph at 1,500 feet
The range chart versus speed for the 2,019 gallons of fuel option is
a gentle curve dropping to around 1,625 miles at 190 mph, then a
vertical drop to 1,250 miles at the same speed then a near straight
line to 700 miles at 225 mph.
The range chart versus speed for the 1,272 gallons of fuel option
has the same pattern, down to 1,000 miles at 190 mph, the drop to
750 miles at the same speed then the linear decline to 450 miles at
225 mph. However at 10,000 feet range is less than at 1,500 feet
until 170 mph where the two curves meet at 1,200 miles, at 10,000
feet the vertical drop is at 205 mph, from 1,100 to 800 miles, then
another curve, declining to 475 miles at 243 mph.
USN Range: Maximum range and range versus speed curves
assume no fuel used during warm-up or take-off and no fuel
allowed for reserve. The effect on fuel consumption resulting from
climb (at normal rated power, auto rich) to designated altitude
and descent has been included. Range calculations based in
tests or specification data have been found to be optimistic,
accordingly, all rates of specific fuel consumption have been
suitably increased. Where engine requirement data are used,
they are increased 15%; where flight test data are used, they
are increased by 5%. For jet propulsion one-half of these
percentages are used. Bombs, torpedoes, all droppable tanks
and radar are carried the full distance.
The above B-24 USN ranges use the 5% correction factor.
For some comparison.
RAF Range: Non fighter types, deduct the fuel used in 20
minutes at maximum economic cruise (for warm up, taxying,
take off and climb), deduct a further 30 minutes at maximum
economic cruise to allow for time over target, navigational
errors and emergencies. So no allowance for wind, formation
flying or full throttle use. Fighter types, deduct fuel used in 15
minutes at maximum power at sea level (for warm up, taxying,
take off and climb), range is then at maximum economic cruise
on the remaining fuel.
Spitfire I, normal weight 6,255 pounds, 415 miles at 304 mph
at 15,000 feet, 1.4 hours endurance, 575 miles at 180 to 190
mph at 15,000 feet, 3.1 hours endurance, 87 octane fuel, 484
pounds available for cruise out of 630 pounds or 84 gallons carried.
Spitfire II, normal weight 6,238 pounds, 335 miles at 304 mph
at 15,000 feet, 1.07 hours endurance, 530 miles at 180 to 190
mph at 15,000 feet, 2.86 hours endurance, 100 octane fuel, 414
pounds available for cruise out of 605 pounds or 84 gallons carried.
Spitfire V, normal weight 6,460 pounds, 335 miles at 310 mph at
15,000 feet, 1.08 hours endurance, 480 miles at 180 to 190 mph
at 15,000 feet,100 octane fuel, 389 pounds available for cruise
out of 630 pounds or 84 gallons carried.
The mark I and II carried 8x0.303 inch with a total of 2,800 rounds,
the mark V 2x30mm with a total of 120 rounds, and 2x0.303 inch
with a total of 1,400 rounds.
Wellington Ic, 6x0.303 inch guns, 7,000 rounds of ammunition,
take off weight 30,000 pounds, 25 minutes to 10,000 feet, 87
octane fuel, 518 pounds of fuel deducted from total for 50 minute
allowance. Permanent fuel tankage is 750 gallons, auxiliary tank
280 gallons.
Cruise at 195 mph at 10,000 feet,
4,500 pounds of bombs, total fuel 518 gallons = 3,888 pounds,
range 1,055 miles, endurance 5.4 hours.
2,800 pounds of bombs, total fuel 750 gallons = 5,620 pounds,
range 1,600 miles, endurance 8.2 hours.
500 pounds of bombs, total fuel 1,030 gallons = 7,720 pounds,
range 2,255 miles, endurance 11.55 hours.
Cruise at 165 mph at 10,000 feet,
2,800 pounds of bombs, total fuel 750 gallons = 5,620 pounds,
range 1,805 miles, endurance 10.95 hours.
500 pounds of bombs, total fuel 1,030 gallons = 7,720 pounds,
range 2,550 miles, endurance 15.5 hours.
Essentially aircraft performance is a series of graphs, a single
set of figures needs a lot of explanatory notes if you are being
really exact. Different air forces had different measurement
criteria which helps explain why, over and above individual
variability, tests of the same aircraft type could have different
results.
Geoffrey Sinclair
Remove the nb for email.
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