In all the data I have on Lavochkins La 5 /7 I have never seen a reference to an external drop tank.
The early Lagg3 did have the facility to take external drop tanks on its bomb shackles. It also had the facility to take 6 x M82 rockets.
Re endurance of the La7 plse see below
Approved. 1st Deputy Chief of GK NII VVS Losyukov. 6 Jan 1945.
REPORT No 2
on results of flight trials for fuel consumption and range measurements
of La-7 No38103254 with ASh-82FN engine and VISh-105V-4 propeller.
The object of research
La-7 No 38103254 produced by plant No 381... Total weight 3265 kg, fuel tanks
capacity - 460 litres. The landing-gear and the tail wheel were up,
the canopy was closed, the cap of oil-cooler and the skirt of engine cowl
were set "along the flood" (feathered).
The results of the tests.
The measurements of fuel consumption with working engine had been carried
out on the ground and during a climb at max climb rate. As a result it has
been established that fuel consumption of a working engine is 2.35 l/min
on the ground (during warm-up and engine test, taxiing to and from the
starting position).
Fuel consumption at climb to H at maximum climb rate mode, in litres
n=2400RPM
H,m 1000 2000 3000 4000 5000 6000 7000
Q,litres 15 25 35 45 55 65 80
IAS, km/h 270 270 270 265 260 255 250
Chart of range and level flight duration of a/c La-7 No38103254 at different
flight modes at V/n=const (constant speed and RPM), G tot=3265kg (total
weight) and V fuel=460 l (fuel volume)
n, Supercharg. Speed, km/h q, Qf, Till the dry tank:
RPM pressure, IAS TAS lit./km lit./h Range of Level flight
mm of merc. level flight, duration,
pile km h-min
H=1000m (1st speed of supercharger), fuel supply for level flight - 365 l
2400 1020 575 608 1.020 620 355 0-35
2200 875 530 560 0.800 448 455 0-49
2000 745 480 508 0.655 333 555 1-06
1800 665 430 455 0.585 266 625 1-22
1600 610 385 407 0.560 228 650 1-36
1500 580 360 380 0.550 209 665 1-45
H=3000m (1st speed of supercharger), fuel supply for level flight - 345 l
2400 990 554 644 0.975 628 355 0-33
2200 830 510 588 0.745 438 460 0-47
2000 705 460 532 0.620 330 555 1-03
1800 615 415 480 0.575 276 600 1-15
1600 560 370 428 0.555 238 620 1-27
1500 545 345 400 0.550 220 625 1-34
H=5000m (2nd speed of supercharger), fuel supply for level flight - 325 l
2400 1020 513 658 0.910 600 355 0-32
2200 840 470 604 0.700 423 465 0-46
2000 720 430 554 0.600 333 540 0-58
1800 630 385 496 0.560 278 580 1-10
1600 590 340 440 0.550 242 590 1-20
H=7000m (2nd speed of supercharger), fuel supply for level flight - 300 l
2400 870 454 647 0.735 476 405 0-38
2200 685 415 593 0.570 338 525 0-53
2000 590 380 544 0.500 272 600 1-06
1800 515 340 490 0.460 225 650 1-20
1600 465 300 433 0.450 195 665 1-32
Notes:
1. For range and flight duration calculations the following fuel consumptions
are taken into account:
a) for engine work on the ground (warming-up and engine test, taxiing to and
from the start) 35 l per 15 min;
b) for climb to: 1000m - 15 l; 3000 m - 55 l; 7000 m - 80 l;
c) for circle flight before landing - 45 l.
2. To obtain the values of technical range and flight duration add the
following range and time figures to the table values respectively:
1000m - 5km, 1 min
3000m - 15km, 3 min
5000m - 25km, 5 min
7000m - 40km, 8 min
The table of range and flight duration for La-7 No 38103254 with
G full=3265kg, full tank fuel supply - 460 l.
Mode Mode values Level flight
up to dry tanks:
Range, km duration,
h-min
Max. H=1000m(1st sup.sp.),n=2400, Ps=1020mm Me.pl. 355 0-35
speed 3000 1 2400 990 355 0-33
5000 2 2400 1020 355 0-32
7000 2 2400 870 405 0-38
Fast H=1000m(1st sup.sp.),n=2160, IAS=518 km/h 485 0-53
range 3000 1 2160 498 490 0-51
(0.9 5000 2 2160 462 485 0-49
Vmax) 7000 2 2160 408 545 0-56
Near H=5000m(2nd sup.sp.),n=1810, IAS=388 km/h 580 1-10
fast range TAS=500 km/h
Optim. H=1000m(1st sup.sp.),n=1500, IAS=360 km/h 665 1-45
mode 3000 1 1500 345 625 1-34
5000 2 1600 340 590 1-20
7000 2 1600 300 665 1-32
