Overall Dimensions & Weights
The general consensus for dimensions for the La-5FN is
Wing Span: 9.800 Meters
Length: 8.672 Meters
The source I originally used when building this model used measurements in feet and inches which made for a slight rounding issue in wing span and as stated earlier, gave an overall length that was about two inches shorter. There is the possibility that the measurements were taken from a museum aircraft and no actual originals survived intact and also the possibility that a rebuild may have combined pieces from the La-7.
One very simple drawing that I have attached (from the Construction Manual) would have been very useful when building the model.
Note that although the shapes are not accurate, the reference line for the aircraft is given as is the relative distance to the thrust line and horizontal stabilizer. I believe my model is canted slightly nose up relative to this drawing but I am not about to correct it because it would involve basically a whole new build for no obvious visual improvement.
-------
As stated earlier, the weights of the La-5FN varied a bit so one has to decide what source of information to accept.
A breakdown of loads is given in the Rechlin evaluation by Lerche:
Weight empty equipped 2773 kg
Fuel (460 l) 354 kg
Lubricant (51 l) 46 kg
Ammunition (2x 200 rounds) 94 kg
Pilot 80 kg
Take-off weight 3347 kg
Weighing:
Left wheel 1437 kg
Right wheel 1484 kg
Tail wheel 426 kg
Take-off weight 3347 kg
This was a captured and repaired aircraft of unknown production series and the performance that was recorded was much lower than other sources give. Thus it is a matter of picking what data is useful from this report.
The weights and general performance from some Internet sources seem to be much more in line with expectations.
One source states:
Empty Weight: 2828 Kg
Loaded Weight: 3290 Kg
Maximum Take-Off: 3390 Kg
The difference between Loaded Weight and Empty Weight is clearly too low with what we know the loads to be.
I believe the numbers are actually labeled incorrectly and if the Maximum Take-Off Weight is taken to be the "Loaded Weight", the numbers add up to within 1 Kg of the recalculated weights of the loads.
It may seem to some that my math is not so good, but more on this later as I provide more data from the manuals.
Please note that the Germans were not likely to have had a complete set of aircraft manuals when servicing their La-5.
- Ivan.
1 Attachment(s)
La 5FN General Configuration
I seem to have forgotten to attach the General Configuration image from the Construction Manual in the prior post.
1 Attachment(s)
La-5FN Fuel System - Corrected Data
It turns out that the Fuel Tank Capacities of the La-5 series differed just a bit from those of the La-7 although the schematics look identical.
Attached below is the description from the Construction Manual for the La-5FN.
The Center Tank is 168 Liters Capacity (Not 170 Liters as on the La-7)
The Outer Tanks are 148 Liters Capacity (Same as on La-7)
For a Total of 464 Liters instead of 466 Liters.
- Ivan.
1 Attachment(s)
Shvetsov M-82FN / ASh-82FN Engine
Attached are two extracts from the section of the La-5FN Construction Manual describing the Engine.
From the first image, one can get
Basic Description:
Double Row
14 Cylinder
Dimensions for Displacement:
Diameter of Cylinder - 155.5 mm
Stroke - 155 mm
Compression - 7.0
Reduction - 11:16
and other interesting but somewhat irrelevant information for the simulator such as
Overspeed limitations
Supercharger Drive Ratios for Low and High Blower
Engine External Dimensions
Take-Off Boost (WEP)
2500 RPM
1200 mm (--20 mm)
Normal Power (Military)
2400 RPM
1000 mm (+- 10 mm)
Note that the "minus-minus 20 mm" in the Take-Off setting is not a typo.
Other sources such as the flight manual list this boost setting as 1180 mm (+-20 mm)
The La-7 manual lists this as 1180 +-20 mm....
-------
1 Attachment(s)
Engine Critical Altitudes
Attached is an image showing Boost limitations and Engine Critical Altitudes as listed in the La-5FN Construction Manual.
Low Blower
2400 RPM
1000 mm Boost
1650 Meters critical altitude
High Blower
2400 RPM
1000 mm Boost
4650 Meters critical altitude
What is not listed here is the following:
Low Blower - 1650 HP
High Blower - 1450 HP
Take-Off - 1850 HP
Blower Shift Altitude from the Flight Manual is 4000 Meters.
Take-Off Boost may only be used in Low Blower.
Note that this is an aircraft limitation that CANNOT be reflected in the CFS AIR file.
From about 2000 Meters to 4000 Meters, the engine performance will be relatively poor.
This unfortunately will be the altitude range in which our single speed supercharger will hit peak performance.
WEP will be pretty much useless just above 1650 Meters but in CFS, if we allow WEP, it will be effective to at least twice that altitude.
Such are the limitations with CFS flight models.
- Ivan.