Captured German La-5 flight test

[niklas]

Bogun- even books of the later GDR (german democratic republic, eastern germany) list a FNW engine for the La-7 for example!!

Face it, this was the western designition for the serial 1200mm 1850PS Ash82 engine with direct fuel injection

Look at the climbrate with combat power only. It´s OK. And look at the weight, the La-5FN was 50kg heavier than in many russian sources.
Climbrate is always a good indicator for engine power!! Once more, climbrate is ok, thus engine output was ok.

You always say it was repaired etc. . I´d like to see the sources to proof that. But it would be a wonder to see sources from russia. Just BlaBla as usual.

niklas

[Tilt]

Originally posted by Bogun

The only engine which was marked as M-82FNV (Firsirovanniy Neposredstvennogo Vpryska – Busted, Direct (Fuel) Injection) was installed on test batch of LA-5FN sent to front sometime in April-May of 1943. Those engines were clearly marked as this - M-82FNV. Shortly after official designation for this engine was finalized and next production batch of La-5FN had engines marked as M-82FN.
Not long  after that the name of the engine was changed again to ASh-82FN in recognition of the contribution of its designer A. Shevtsov.

I have  publications that concurr that an M82 FNV or M82NV ( V as in vprysk)was installed into a prototype La5F (bubble top) White 3(39210102) it was uniquely called the La5FNV.

The April -May batch of La5FN's were  a bit of a muddle and did not come off a series production line but AFAIK were cobbled toegther using wings and fuselages from previous types.

200 units so manufactured were on the front line for June. Actual serial production was set into motion during Autumn 43 when the Ash82 FN was available in sufficient numbers.

All following Lavotchkin fighters have modified ASh-82FN engines marked exactly as ASh-82FN. There was no such thing as La-5FN(V).

Engine ASh-82FN(V) – (V for Vysotny – High Altitude) was the modification of ASh-82FN was never installed on La-5FN, nor was it ever installed on any other Lavotchkin prop fighters. ASh-82FN(V) engine was installed on Tu-2 bomber and some of the post-war transport planes.

I am not sure what you mean by modified......however I would agree that the production La5FN was never referred to as the La5FNV by the VVS  my use of the (V) was mine just to show that it had that engine.

However i have always believed that it was the M-82FN (or FNV) that powered the Tupelov Tu-2.



I have original test data for the La 7TK which used the Ash82 FN  (some other publications refering to it as an Ash82FNV) with a pair of TK3 superchargers. It never went into serial production.

I must admit tho that your explanation that the M82 FNV became the Ash 82FN has caused me to go over all my notes.  M and Ash are often interchanged both before and after each other in several  publications and I always considered it much as we see it  similarly confused between Me and Bf when refering to the 109.

I have always believed that V stood for high altitude and several publications show it as being used in the La7 after the initial batch. One publication explains that there is little actual performance difference

Hence if you read the history of the Ash 82 FN or indeed the M82 FN the later V turns up spring 44 onwards in serial aircraft.

It looks like that La-5FN tested in Rechlin was one of the first batch of La-5FN produced on April of 1943, which crash-landed in East Prussia sometime in the Fall of 1944 and somehow restored to a flying condition. It was the only La-5FN captured by Germans and it was way past its resource limit.

In Gordons latest book (red star publications) we find a picture of the la5FN at Rechlin and it shows the  rhomboid engine emblem on the cowl. The early April/May 43 batches still used the circular emblem with the cyrilic FN. The rhomboid was in use during the later serial production batches when they actually changed I am not sure.

Even so given the short design life of these air craft it quite possibly was past its expected life.

[HoHun]

Hi Tilt,

>Lowering speed to 180 it refers to the "damping being reduced".....

>I read this that roll rate control (as opposed to actual roll rate) was damped (almost lost) during the slat extension  but returned at lower speeds up until point of stall.

Actually, the German is quite clear:

At 210 - 200 km/h IAS the control forces drop to zero, then into overbalance. That means that if you displace the ailerons a bit, they pull on the stick and try to displace themselves even further.

At 180 km/h, the roll damping vanishes. That means that any roll movement will continue unless actively arrested by the pilot. (Of course, with over-balanced ailerons, that's easier said than done.)

Lerche found the overbalance even worse in the turn than in level flight.

Regards,

Henning (HoHun)

[HoHun]

Hi Bogun,

>It looks like that La-5FN tested in Rechlin was one of the first batch of La-5FN produced on April of 1943, which crash-landed in East Prussia sometime in the Fall of 1944 and somehow restored to a flying condition.

Quoting Lerche: "Das Flugzeug befand sich in einwandfreiem Zustand."

My translation:"The aircraft was in immaculate condition."

Translation above: "The aircraft itself was fully servicable."

>The fact that pilot was not able to reach engine rated manifold pressure of 1200 mm C.S. clearly indicate that Germans were not able to bring this engine back up to spec.

They were able to reach 1180 mm H2O, though. As manifold pressures were given with a 1% - 2% variation even for German-manufactured engines with full factory support, the lower manifold pressure means nothing by itself.

>Well, Lerhe did the best he could with what he had at hands, but in no way it represent real performance of normal La-5FN.

In this point, I agree with you. I believe - though I can't prove it - that the test aircraft had a hidden problem somewhere.

Regards,

Henning (HoHun)

[Tilt]

Thx Ho Hun

so the actual characturist is the reverse of my reading.......

at 210 to 200 once started it want s to roll......below 180 once started it will continue to roll until reverse aileron is employed..............


its a real stunt plane............


Is this the same in both directions? does he mention this?

Originally posted by HoHun
Hi Tilt,


Actually, the German is quite clear:

At 210 - 200 km/h IAS the control forces drop to zero, then into overbalance. That means that if you displace the ailerons a bit, they pull on the stick and try to displace themselves even further.

At 180 km/h, the roll damping vanishes. That means that any roll movement will continue unless actively arrested by the pilot. (Of course, with over-balanced ailerons, that's easier said than done.)

Lerche found the overbalance even worse in the turn than in level flight.

Regards,

Henning (HoHun)

[Bogun]

Guys, unlike in western publications, engine model numbers are not used interchangeably in Russian military or technical literature, not was it used interchangeably in serial numbers plate attached to the engine. I assume Germans took designation of M-82FNV from such label on the engine. This designation was not used on Russian engines even in the end of 1943. You can date the engine by it.

The difference between 1180 and 1200 mm C.S. is significant.
Remember that rated manifold pressure of M-82F engine was 1160 mm C.S. and it produced only 1700 hp on take-off. This plane in Rechlin tests not even close to normal speed and climb rates – clear indication that engine is de-rated.
Another indication of engine troubles was mentioning of exhaust fumes in cockpit – problem solved right after few initial batches of La-5FN. I already explained this on UBI forum. Soviets failed to seal the firewall between engine compartment and cockpit hermetically because of large amount of piping and wires going through it. In the flight because of lower pressure in the cockpit – exhaust fumes were leaking there from higher pressure engine compartment. The solution was simple – Soviet designers introduced another outside air intake, which raised pressure in the cockpit – problem was solved very quickly. It reappear again in pre-production batch of La-7 and that time it was solved same way, only faster. If it was indeed “new” La-5FN – then Germans didn’t repair it properly after the crash.

I have been reading some bits about where that plane was captured and in that publication even the VVS unit was mentioned, but it was long ago, sorry. Also, Oleg Maddox stated once that that La-5 was restored after force landing, some parts remanufactured – he may have more info on it.

There were some changes mainly related to optimizing airflow made in Ash-82FN engine when it was introduced to La-7 line, oil piping was also changed significantly because of repositioning of supercharger air intake and oil coolers, but as far as I know name remained the same – Ash-82FN.

Name ASh-82FN(V) was introduced with the changes needed to optimize this engine for installation in the bombers (something related to propeller gear ratio – I am not a specialist). This engine was never installed in any La fighter planes, as far as I know. If Western publications mention it – it is most likely in error.

Different manufacturing plant producing La planes were using different emblems on an engine cowling (or were not using it at all). On some of them single or two letters were written – F or FN for example, some planes had model name like La-7 written. Often this label was painted over at the front. I am really curious what was written on that “rhomboid” label in that Gordons book. What is this book, by the way?

Nikas, you can take you usual BlaBla and stuff it you know were...

[Tilt]

Note the longer pitot tube and  lack of wheel covers.........

You can see the  FN engine rhomboid  on the cowling cover, this suggests to me that its later (Sept 43 onwards) than the early batch.

The Book is Lavochkins   piston engined fighters by Yefim Gordon translated from and original publication by sergy and Dmitriy Kommissarov.

Bogun do you have any literature  verifying your conclusions re the  "V" (even in Russian)............. I have re read my notes and if I assume a critical error in one publication then your version is plausable.

I am very prepared to believe that the machine under test was a year old............ I would be surprised if it was one of the batches rushed to the Kursk front mid 43.

[niklas]

Originally posted by Bogun
I assume Germans took designation of M-82FNV from such label on the engine. This designation was not used on Russian engines even in the end of 1943. You can date the engine by it.

Wrong. Engine development was top secret. German intelligence service did definitly NOT know exactly about all new developments from russia. They seem to knew about direct fuel injected engine project, however.

The difference between 1180 and 1200 mm C.S. is significant.

no, it´s not. 1000mm is ~1600PS, so 1180mm is less than 50PS difference. Actually it´s a hint that they really looked on the instrument, reading the value, thus confirming that it was a 1850PS engine. When they have listed just rated power, they
would have written 1200mm!

Remember that rated manifold pressure of M-82F engine was 1160 mm C.S. and it produced only 1700 hp on take-off.

And rated alitutde of combat power was just 500m.

This plane in Rechlin tests not even close to normal speed and climb rates – clear indication that engine is de-rated.

Not true. Top speed was poor, agreed. But russian speed claims are ridicolous. The truth for a normal aircraft in service condition is probably in the middle.
Climbrate is 100% ok. When an aircraft produces more drag, because it´s not so carefully finished like in russian "what can be achieved" top speed trials, it will also influence the climbrate at bit. The difference is really small on the other hand.

You said you have proofs that the aircraft was reapaired. I´m stiill waiting for your proofs. Do you have them? Show them! Or was it just BlaBla that you can´t backup??

Here 2 docs that show that the common term for the direct fuel injected engine was FNW in Germany:

Engine Chart and description, compare to other sources, compare boost.


The doc of the GDR. Note topspeed claim, Bodennähe is sealevel. 595 at sealevel for La-5FN (lol) and 665km/h (!!) for La-7 (rotfl). Oh, communist propaganda was, is and will always be the most entertaining one.
Note the incorrect designitions of engines (germans did not know about the correct ones, for sure)
 

niklas

[HoHun]

Hi Tilt,

>Note the longer pitot tube and  lack of wheel covers.........

There are two more photographs of the "21" in Lerche's book (from the 4:30 h and 1:30 h positions). These may actually be some of Lerche's own shots, he used 76 of these to his book though unfortunately without marking them.

>The Book is Lavochkins   piston engined fighters by Yefim Gordon translated from and original publication by sergy and Dmitriy Kommissarov.

Does it have a list of photo sources? Maybe Lerche is listed there.

>I am very prepared to believe that the machine under test was a year old............

Wouldn't your observation of the armour strength you mentioned earlier contradict this?

Regards,

Henning (HoHun)

[HoHun]

Hi Tilt,

>There was a 50kg weight imbalance that still intrigues me.

Mad idea: One wing wood, one wing metal construction, result of a hasty repair at the front? On the other hand, the report WOULD have mentioned that :-)

Regards,

Henning (HoHun)

[HoHun]

Hi Bogun,

>I assume Germans took designation of M-82FNV from such label on the engine.

I'd tend to agree, though the use of "intelligence" information is a possibility, too. Unfortunately, Lerche's report refers to previous reports on engine and airframe so he left out the details :-(

>The difference between 1180 and 1200 mm C.S. is significant.
Remember that rated manifold pressure of M-82F engine was 1160 mm C.S. and it produced only 1700 hp on take-off.

What type of engine was the M-82F? I'd assume there were more differences than just manifold pressure.

For the FNW, the loss of 2% of manifold pressure shouldn't cause a significant loss of power unless there were other factors involved.

>This plane in Rechlin tests not even close to normal speed and climb rates

Actually, the problem may have been that they couldn't maintain emergency power. The 16 - 17 m/s climb rate was achieved at rated power, using emergency power climb would have been much better.

From a rough calculation based on the German power chart posted by Niklas, I'd say a 16.5 m/s @ 1550 HP Lavochkin would climb 21.3 m/s @ 1850 HP. Does that sound more like realistic Lavochkin performance?

>If it was indeed “new” La-5FN – then Germans didn’t repair it properly after the crash.

It's my impression that the La-5FN didn't crash. Lerche explicetely mentions the capture of an airworthy La-5, and he was able to fly to the front to pick it up and bring it back without any delay for repairs. He also doesn't mention any test flights as typically done after a repair though he had his logbook available when he wrote his book.

Additionally, if it had been repaired, the report wouldn't have read:

"Das Flugzeug befand sich in einwandfreiem Zustand."

But rather:

"Das Flugzeug wurde einwandfrei wiederhergestellt."

("The aircraft was restored to fully servicable condition.")

I believe the crashed La-5 may have been an earlier model displayed at the prize aircraft show at Rechlin (and photographed there). Maybe there's some confusion between these two different captured Lavochkins.

>Name ASh-82FN(V) was introduced with the changes needed to optimize this engine for installation in the bombers (something related to propeller gear ratio – I am not a specialist). This engine was never installed in any La fighter planes, as far as I know.

Was it available in September 1944? If the captured La-5FN was an old hack that had received a bomber engine somewhere in its history, this would certainly explain its poor performance :-)

(However, I consider this unlikely.)

Regards,

Henning (HoHun)

[niklas]

Bogun, still waiting for your answer. You said the La-5FN was repaired. Show your proofs or i´ll have to take it for a lie!

Someone from germany published a picture of the german original document, maybe interesting for you. It´s really in bad shape, and the scan isn´t perfect too.



niklas

[HoHun]

Hi Niklas,

>Someone from germany published a picture of the german original document, maybe interesting for you. It´s really in bad shape, and the scan isn´t perfect too.

Thanks! :-)

After a thorough analysis of the performance data presented in this thread, I've reached the conclusion that the La-5"FNV" tested by Lerche did have the full power from its M-82FNV engine available.

The climb rate of 17 m/s at sea level matches the Tsagi data of about 18 m/s well, and my estimate of an increase to 21 m/s if emergency powere were available meets the Tsagi data of 22 m/s, too.

The performance increase from 490 km/h to 520 km/h at sea level is just what you'd expect from a power increase from 1550 HP to 1850 HP, so emergency power had the correct HP output, too.

Based on these data points, the power curve for the M-82FNV engine chart posted above results in results quite similar to those actually achieved by Lerche, so the engine of the capture La-5"FNV" obviously was close to specs, too.

However, comparing the Tsagi speed data to Lerche's speed data reveals a significant difference: Lerche achieved just 490 km/h at sea level, while Tsagi data is 550 km/h. The same difference persists throughout the entire altitude range.

The conclusion to draw from this is that Lerche's test aircraft had a significantly higher coefficient of drag than the Tsagi test aircraft.

Since the aircraft depicted above is in good shape, with spinner fitted and the original cowling, and Lerche's report confirms that no problems were recognized with the La-5"FNV", the problems must have been very subtle.

The history of MiG I-210 and I-211 (which is where the La-5's cowling originated) suggests that the drag of the Lavochkin-type engine installation increased considerably due to vortex flow caused by lack of airtightness of the cowling installation. I speculate this could be the factor that made Lerche's La-5"FNV" so slow.

Whether this problem was specific to Lerche's test aircraft, or whether it was common - or even typical - for Lavochkins in VVS service can't be determined from Lerche's report, though.

Regards,

Henning (HoHun)

[niklas]

Well, i have to say it´s always remarkable how many original documents are meanwhile around from western sources, while you can hardly find an original document from the east. Does someone have an original flight report? I know only about .doc sources. Never saw an original flight test document with detailded description.
It´s getting almost ridicolous if you can read (escpecially in a particular other forum) that they can´t show documents due to copyright. Lol, russia is still main place for illegal copies of CD etc. Many eastern countries, Romania for example, did not know a copyright law until the 90ies. And today they can´t show docs with an age of 60years due to copyright. BAH. Liers. They don´t have anything. OR they know the truth and hide it because their aircraft suddenly wouldn´t perform so uber....

Just look what Bogun wrote. Can he prove it? Where are his sources. Just nice words, hot air. Pff....

niklas

[MiloMorai]

Not only CDs niklas.

On this site you can get complete scanned images of Squadron/Signal InAction books that are still on the shelves in stores.

http://www.aviacherteg.narod.ru/avia/