La-5 / La-5F / La-5FN / La-7 / La-7B-20

[mad_max]

According to my Russian Wife the right part with 1944 is what would be called a standard to be met; similar to what the government would tell developers what performance they wanted. Notice there's no aircraft build number included in that section.

 

[Laurelix]

There's also this

580km/h at SL - 1570hp
616km/h at SL - 1850hp
-
677km/h at 6250m

 

[mad_max]

Here's more data I've collected through the years. My GD folder on the LA series.

La Series – Google Drive

 

[Ivan1GFP]

Ivan and a few others on this site are way more versed in the politics of the USSR during WW2 than I am.

I will attempt a simple answer...?
Arkadi Shvetsov.s
M-82 (A): 1,330 PS normal power & high S/C (1,510 PS combat power & low S/C)
M-82F: 1,350 (1,700) Take-off: 1,700 PS @ 1,140 mm Hg.
M-82FN: 1,470 (1,850) Take-off: 1,850 PS @ 1,200 mm Hg.
ASh-82FN: 1,470 (1,850) Take-off: 1,850 PS @ 1,200 mm Hg.

Hello Corsning,

If that "Ivan" is me, then thanks for the vote of confidence, but it is a bit misplaced. I just read a bit of Russian and Tomo Pauk is much better at it than I am.

I have been collecting data fairly recently on the La-5FN and here is what I have found that is somewhat relevant to this discussion:
The engine was a Shvetsov M-82FN or ASh-82FN. It was the same in the La-5FN and La-7.
From the La-5FN Flight Manual and Construction Manual (pretty much an E&M manual):
Take-Off Power was 1850 HP @ 2500 RPM with 1180 mm Hg Manifold Pressure.
Nominal Power was 1650 HP @ 2400 RPM with 1000 mm Hg Manifold Pressure at critical altitude 1650 Meters in Low Blower.
Nominal Power was 1450 HP @ 2400 RPM with 1000 mm Hg Manifold Pressure at critical altitude 4650 Meters in High Blower.
Supercharger gear change was at 4000 Meters altitude.
As Tomo Pauk pointed out, "Nominal Power" is what their manuals call it. I normally think of it as pretty much equivalent to our "military power" setting.
Their Take-Off / WEP rating was not useable except in low blower and I believe the limit was 5 minutes duration maximum.

As for weight of the aircraft, I believe they tended to vary A LOT depending on the production series and also depending on whether major structural members were Delta wood, Pine, or Light Alloy. The Rechlin Report by Lerche gives an idea of what the major weights were but I believe the numbers are a bit off.
I believe the numbers from "airpages.ru" seem to be reasonable and not in great disagreement with those of the Rechlin Report.
The problem is that the data is mislabeled.
They list 2828 Kg as Empty Weight. This is probably what we would consider "Basic Weight".
They list 3390 Kg as Maximum Take-Off Weight but I believe this is actually the Loaded Weight.
Here is the Weight Breakdown and how I came to this conclusion:
2828 Kg Basic
80 Kg Pilot
52.3 Kg Lubricant for 58 Liters Capacity. (Rechlin flew with 51 Liters weighing 46 Kg.)
333.6 Kg Fuel for 464 Liters (2 x 148 Liter, 1 x 168 Liter from manual)
94 Kg for 400 rounds 20 mm ammunition
----------
3387.9 Kg which is pretty close to 3390 as listed.
This is only a few Kg over what was listed in the Rechlin Report.

As for maximum level speed, I believe the anything from about 390 MPH to about 403 MPH is reasonable because construction quality varied quite a bit.
As for the altitude at which it was achieved, my BELIEF is that anything in the 20,000 feet / 6000 Meter range is unrealistic.
The engine had a critical altitude of only 4650 Meters. Any greater altitude for aircraft critical altitude would have to be due to ram effect and I can't see that as adding another 1400 to 1500 Meters.

- Ivan.

Minor Correction: In the weight calculation, I used the Oil Capacity from the La-7. The Oil Capacity for the La-5 and La-5FN was 60 Liters, so with the corrected weights, we have:

2828 Kg Basic
80 Kg Pilot
54.1 Kg Lubricant for 60 Liters Capacity. (Rechlin flew with 51 Liters weighing 46 Kg.)
333.6 Kg Fuel for 464 Liters (2 x 148 Liter, 1 x 168 Liter from manual)
94 Kg for 400 rounds 20 mm ammunition
----------
3389.7 Kg which is VERY close to 3390 as listed.

 

[mad_max]

The Red Star Series of books are a darn good red and if you're really interested in Soviet Aircraft of WW2 era, then I suggest you get a copy. Over 140 ages of text, photos and drawings. From prototypes to production airframes listing problems, build quality just everything you would want to know. Yes I have a copy and you can't buy it from me.

The La series book.

Amazon product ASIN 1857801512

 

[Laurelix]

So from what I was able to gather

M-82A
1400hp at SL (Military Power)
1700hp at SL (WEP)

M-82F is identical to A in power output except for longer Time between overhaul and improved cooling and lubrication system allowing it to use the WEP power continuously whereas the M-82A couldn't.

M-82FN is a M-82F with direct injection
1570hp at SL (Military Power)
1850hp at SL (WEP)

——-

Because the 1700hp for M-82A is so limited
The maximum speed for La-5 by the Soviets was listed at 1400hp at SL, not with 1700hp.

=====

Maximum Speed at Sea Level
La-5
526km/h at SL - 1400hp

La-5F
561km/h at SL - 1700hp

La-5FN
577km/h at SL - 1850hp
638km/h at 6200m

La-7
616km/h at SL - 1850hp
677km/h at 6200m

La-11
613km/h at SL - 1850hp
674km/h at 6200m

La-9
630-640km/h at SL - 1850hp
690-700km/h at 6200m

 

[Baball]

Your thread reminded me that I had a copy of an official flight test report for the La-5 in which the maximum SL speed at nominal power (1400HP) was 509 hm/h and 535 km/h at takeoff power (1700HP).

 

[Laurelix]

Your thread reminded me that I had a copy of an official flight test report for the La-5 in which the maximum SL speed at nominal power (1400HP) was 509 hm/h and 535 km/h at takeoff power (1700HP).

It wouldn't make sense cuz La-5, La-5F and La-5FN have same drag coefficient

How can La-5F do 561 with 1700hp
But La-5 only do 535 with 1700hp

(Only difference between the two being that La-5F's engine doesn't want to blow up when using 1700hp)

The only explanation I could give is that it's build quality was extremely sub par

 

[bf109xxl]

It wouldn't make sense cuz La-5, La-5F and La-5FN have same drag coefficient

How can La-5F do 561 with 1700hp
But La-5 only do 535 with 1700hp

The maximum speed depended drastically on the manufacturing quality and could vary even for airplanes of the same batch. The La-5 suffered from A LARGE NUMBER of defects - especially at the beginning of serial production. It was a long, long story of the La-5 improvement. It became more or less appropriate rather by the end of 1943.

 

[Laurelix]

The maximum speed depended drastically on the manufacturing quality and could vary even for airplanes of the same batch. The La-5 suffered from A LARGE NUMBER of defects - especially at the beginning of serial production. It was a long, long story of the La-5 improvement. It became more or less appropriate rather by the end of 1943.

That's true
I guess it's worth to point out this as well

Your La-5 report says
509km/h at SL - 1400hp
535km/h at SL - 1700hp

However…
1700 / 1400 = 1.2143
Cube rooted = 1.0669
509 x 1.0669 = 543km/h with 1700hp

-

Then there's the
LaG-5 Early Series: June 1942: M-82 (A): 3,365 kg. combat weight.
512 km/h / S.L.
580-583 km/h / 6,250 m.

512 x 1.0669 = 546km/h with 1700hp

-

Then there's the
La-5F Early: January 1943: M-82F: 3,365/3,366 kg.
551-552 / S.L.
590-598 / 6,250 m.

551 / 1.0669 = 516km/h with 1400hp

-
Then there is the
La-5 Type 39 prototype with 1 x 20mm + 1 x 12.7mm:
M-82FN Early 1943: 3,200 kg.
518 / S.L.
600 / 6,500 m.

518 x 1.0669 = 553km/h with 1700hp

-

Then there is the
La-5 Standard: August 1942: M-82 (A): 3,357 kg.
525/ S.L.
585-588 / 6,250 m

525 x 1.0669 = 560km/h with 1700hp

-

Finally we have…
La-5F No.99391160: June 1943: M-82F: 3,202 kg.
561 / S. L.
619 / 5,790 m.

561 / 1.0669 = 526km/h with 1400hp

To conclude…
Shittiest La-5's achieved 509km/h at SL with 1400hp
The High quality La-5's achieved 526km/h at SL with 1400hp

17km/h at SL discrepancy

 

[bf109xxl]

The real engine power was frequently lower than specified.
The aerodynamic perfection of the early versions was much worse than of the later ones.
Usually prototypes were manufactured much more carefully, etc.

The report's figures only indicate poor manufacturing quality and numerous problems with both the airplane and the engine.

 

[Laurelix]

The real engine power was frequently lower than specified.
The aerodynamic perfection of the early versions was much worse than of the later ones.
Usually prototypes were manufactured much more carefully, etc.

The report's figures only indicate poor manufacturing quality and numerous problems with both the airplane and the engine.

Yeah
If it does 509 with 1400hp
Then it's only doing 1625hp to get 535

 

[Laurelix]

This might be of use: test results
Translation by yours truly, so you know whom to blame.

Just letting you know I sent you request to get access to view it

 

[wrathofatlantis]

The real engine power was frequently lower than specified.
The aerodynamic perfection of the early versions was much worse than of the later ones.
Usually prototypes were manufactured much more carefully, etc.

The report's figures only indicate poor manufacturing quality and numerous problems with both the airplane and the engine.

Another thing worth adding is that production radial Lavochkins, at least up to the La-5FN, overheated the cockpit, sometimes even in the winter, and the firewall also leaked dangerous carbon monoxide gasses in the cockpit, while the sliding canopy was not always great in optical quality.

For all these reasons, radial engine Lavochkins, up to and including the La-5FN, were mostly flown in combat with the canopy fully open, even in the dead of winter. This probably cut at least 20 km/h from most of the speed data shown in this thread.

What is remarkable is that despite this handicap, The La-5FNs below 4.5 km still were faster, canopy open, than Me-109Gs without MW-50 injection, as the G-6 without MW-50 had a dogleg in its speed that made it fairly slow below about 13 000 ft.

The La-5FN in combat, canopy open, was still about 10-20 km/h faster than the G-6 below 13 000 ft, so that should give a rough ballpark of how much the open canopy cut into its figures down low, which can then be extrapolated to speed losses higher up.

The open canopy issue should not infer the Lavochkins were badly made. In fact the wood surfaces were remarkable for their quality right from the early Lagg-3 production. But the adaptation of a radial engine, that was not intended from the start, meant there were engineering issues that were only sorted out later on. Probably the worst thing about La-5s were their short fuel endurance: Significantly shorter than 109s.

 

[bf109xxl]

Another thing worth adding is that production radial Lavochkins, at least up to the La-5FN, overheated the cockpit, sometimes even in the winter, and the firewall also leaked dangerous carbon monoxide gasses in the cockpit, while the sliding canopy was not always great in optical quality.

For all these reasons, radial engine Lavochkins, up to and including the La-5FN, were mostly flown in combat with the canopy fully open, even in the dead of winter. This probably cut at least 20 km/h from most of the speed data shown in this thread.

What is remarkable is that despite this handicap, The La-5FNs below 4.5 km still were faster, canopy open, than Me-109Gs without MW-50 injection, as the G-6 without MW-50 had a dogleg in its speed that made it fairly slow below about 13 000 ft.

The La-5FN in combat, canopy open, was still about 10-20 km/h faster than the G-6 below 13 000 ft, so that should give a rough ballpark of how much the open canopy cut into its figures down low, which can then be extrapolated to speed losses higher up.

The open canopy issue should not infer the Lavochkins were badly made. In fact the wood surfaces were remarkable for their quality right from the early Lagg-3 production. But the adaptation of a radial engine, that was not intended from the start, meant there were engineering issues that were only sorted out later on. Probably the worst thing about La-5s were their short fuel endurance: Significantly shorter than 109s.

Not only La suffered from cockpit overheating - e.g., this problem was observed for Yak-9U and Il-10 as well. For the Il-10 the problem was solved only in the post-war time. Quality of the canopy glass was a common problem for the Soviets throughout the war.
Some Soviet pilots in interviews expressed the opinion that maximum speed was not the key parameter. More important was how the airplane could maintain a high average speed in combat, which was always much lower than the maximum speed.