Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: F4UDOA on September 18, 2003, 03:18:03 PM
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Here is a report of the La-5 captured by the Germans.
Notice at rated power flight time is 40 minutes and the performance especially at 20K is much lower than ours.
(http://mywebpages.comcast.net/markw4/la5g1.jpg)
(http://mywebpages.comcast.net/markw4/la5g2.jpg)
(http://mywebpages.comcast.net/markw4/la5g3.jpg)
(http://mywebpages.comcast.net/markw4/la5g4.jpg)
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Originally posted by F4UDOA
Here is a report of the La-5 captured by the Germans.
Notice at rated power flight time is 40 minutes and the performance especially at 20K is much lower than ours.
Does ours carry 200 rounds per gun?
Sakai
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Originally posted by Sakai
Does ours carry 200 rounds per gun?
Sakai
Yes.
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good read. Is there a site with these Rechlin reports?
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Thx posts, F4U.. good read.
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No prob guy's. I luv this kind of stuff.
I picked this off a WW2 message board. This is the only one of it's kind I have seen.
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I don't fly the La-5 much. Anyone have an opinion how the AH La-5 matches up to this document?
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Originally posted by ra
I don't fly the La-5 much. Anyone have an opinion how the AH La-5 matches up to this document?
It is faster than the Fw190A-8 at low altitudes. Slower than the Bf109G-10, which is our only 109 with MW50.
Like all aircraft in AH it lacks the individual quirks such as not being able to use WEP in a climb, the poor oxogen system or the fumes in the cockpit.
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Hi F4UDOA,
>I picked this off a WW2 message board. This is the only one of it's kind I have seen.
According to "Testpilot auf Beuteflugzeugen" by Rechlin test pilot Hans-Werner Lerche who prepared the above report, it's the only one of his reports that survived.
Regards,
Henning (HoHun)
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interesting F4UDOA nice post!!:)
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That's the La-5FN correct?
I think I'm one of the few Aces High pilots who flies the La-5 on a regular basis in the MA. It's a beast below 9000 feet. Above that and she's an easy target for 109's, 190's and P-51's. WEP is useless above 8500ft.
For me, it's the acceleration it has at low altitude. You can turn fight with it as well and out accelerate and out climb just about everything, except the uber La-7.
Spit's and Nik's can turn inside you, but the 5 has a higher sustained turn rate speed and accelerates nicely if you need to extend to reposition for another merge.
It's one of the diamonds in the rough... :D
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Heya HoHun,
Flight test done on captured A/C are definitely the most interesting reads around.
The Germans and the Japanese both captured F4U's. I wish one of those reports would pop up on the web.
BTW, have you read an interview with this man or do you have a contact with him??
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Thanks F4UDOA.
very interesting................
The report is dated March 45 and the plane type is refered to as La5 FNV.
The last La5fn's came off production lines in October 44. They had FNV engines from about July onwards and most a metal main spar for most of the 44 production period.
The 8mm rear plate was reduced to 7 mm on the La7.
This then would most likely be the last and probably the best of the La5 FN's. The 2nd stage of boost on the FNV was slightly better suited to higher altitudes.
Given the report was dated March 45 what 190's and 109's would it have been compared against?
I cannot think what gave a 50kg weight displacement over one wheel.
The statement re WEP again (for me) confuses the use of WEP in the La 5FN (V). I have other documents that infer that its WEP was not of the duration that could be used on the La7 (Albeit for earlier La5FN models.) And only safely used for 2 mins.
However this quotes the manifold pressure at 2500rpm at 1180......I thought it was higher than this at 2500rpm (1200 ). Indeed at 2600 rpm the pilots notes claim that manifold should be 1260 but his could only be used at take of for no more than 30 secs!
Roll data!......at last .........wtg
Stall data..........I wonder what weight this AC was at? I wonder what the effects of prop was would bring if / when full throttle was applied. However given all that it seems to me that AH's stall model is nearer these figures than I would have initially surmised..........wtg HTC.
Landing data is again zero throttle and they seem to miss the actual landing speed other than "throttle should be used for level flight below 112Km/hr".
Galloping landing has been quoted elsewhere...........ps it was worse in the la7 which had slightly longer gear to clear the slightly bigger prop.
Fumes in the cockpit bedeviled all lavochkins
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Hi F4UDOA,
>BTW, have you read an interview with this man or do you have a contact with him??
I've merely read his book. Lerche passed away in 1994.
>The Germans and the Japanese both captured F4U's. I wish one of those reports would pop up on the web.
Well, in the appendix to his book Lerche's son mentions that their research was hindered by some archives that simply were uncooperative for unknown reasons. That could mean that as soon as these archives make more of their material available, one of Lerche's reports could reappear - if we're lucky :-)
(The appendix is dated 1997, so it probably wasn't just the normal cold war non-cooperativeness.)
Regards,
Henning (HoHun)
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Hi Tilt,
>Roll data!......at last .........wtg
Didn't I provide you with a translation of the German version a while back? Unless I worked sloppily, the roll data should have been in there, too :-)
The German version has some gaps in the "A stall in a steep turn ..." paragraph, which the English version has pasted over with neither obvious contradiction nor additional information. I can't tell if they had a clearer copy of the report or if they just relied on guessing.
>The 8mm rear plate was reduced to 7 mm on the La7.
Thanks, that's interesting information!
>Given the report was dated March 45 what 190's and 109's would it have been compared against?
The 8-... designation is an RLM habit - every aircraft (and engine, and propeller ...) seems to have had an 8- designation for some reason. This doesn't give away the version, though.
The use of MW50 tells us that the Me 109 had 1800 HP at least. On the other hand, the poor initial climb attributed to the Fw 190 tells us that is probably was a radial-engined model without the boost increase introduced mid-1944.
(The La-5's climb rate actually is given as 16 - 17 m/s, not as 16.17 m/s as in the above quote.)
Regards,
Henning (HoHun)
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Tilt, I have some questions:
The statement re WEP again (for me) confuses the use of WEP in the La 5FN (V). I have other documents that infer that its WEP was not of the duration that could be used on the La7 (Albeit for earlier La5FN models.) And only safely used for 2 mins.
Does this mean that the La-5FNs had a WEP duration of 2 minutes, as a whole? What are the WEP conditions in that case? Is the quoted '2500rpm @ 1180C.S.' the WEP configuration?
However this quotes the manifold pressure at 2500rpm at 1180......I thought it was higher than this at 2500rpm (1200 ). Indeed at 2600 rpm the pilots notes claim that manifold should be 1260 but his could only be used at take of for no more than 30 secs!
Then the 2600rpm was the WEP, and the 2500rpm merely a higher power setting? The definition of the WEP status concerning the La-5 is confusing> :confused:
Fumes in the cockpit bedeviled all lavochkins
I've also seen this mentioned, but where exactly does it surface in records? From individual anecdotes?
All in all, what documents are your claims on the performance based on? I'm just curious :) If the material may not be disclosed, and cannot be answered on the forum, then I understand.
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Originally posted by Kweassa
Tilt, I have some questions:
Does this mean that the La-5FNs had a WEP duration of 2 minutes, as a whole? What are the WEP conditions in that case? Is the quoted '2500rpm @ 1180C.S.' the WEP configuration?
Then the 2600rpm was the WEP, and the 2500rpm merely a higher power setting? The definition of the WEP status concerning the La-5 is confusing> :confused:
WEP on the La5FN
Firstly actual performance trial data on the La 5FN is rare......... more so than the La7.
Early on when I started getting basic published curves for the range of Lavochkins in various Eastern productions I found that the WEP curve for the La 5FN was missing.
These publications were not hard data and potentially subject to some romantic aspirations.
One was an Article by Alexyenko and Kondratiev that had been translated. I do not know the credentials of either.
Another were a couple of Czech articles.
In an out of print book called "In the cockpit" there is an article written consulting two Czech pilots who flew La5FN's.
They comment from a pilots perspective that engine temperature had to be watched.
Which gave the impression that even max cont. power 1650hp @ 2400 rpm could not be used continuously under all conditions.
They refer to 2500 rpm "take off power" that could only be used for 2 minutes.......
This then starts to agree with the Russian articles.
We then look at the development criteria for the La7 and we see the cowling was subject to considerable work. Not only for external steam lining but also with respect to internal air flow.
Forward air vanes were the same as the La5FN but thespinner was smaller and the front cowl lip radius changed to give a bigger radial intake gap also exhaust rooting and the rear air vanes were redesigned. Also the cowl top intake was removed and intake air was rooted to the engine from behind and not over the cylinders.
What we see is a system far more able to distribute cooling air around all the Ash82 FN's cylinders.
I speculate (and always have) that the La5 FN could not make full use of its engines WEP capability due to its engine cooling limitations.
Rechlin also makes comment that WEP could not be used during climb...........its not clear if this refers to it not being useful (which I dont believe) or infact that it could not be used (like it was not allowed). Airflow through the engine cooling system would have been poor during climb in comparison to higher speed straight flight use.
However I have never had hard data to confirm it beyond the above. My comments above refer to the fact that Rechlin seems to support the view.
The 2500 rpm developing 1180 man is WEP.
Rechlin again refers to the power being 1850 hp at take off which the engine stats in the la7 pilots notes refers to as being derived from 2500rpm and 1200mm.
Ex factory the manifold is 1200 at 2500 rpm 20 mm could even be down to gauge accuracy or indeed supercharger wear or even incorrectly set throttle........its not a biggie.
The ex factory Ash82 FNV spec shows it can generate 2000 hp when revs increase to 2600 and then specifies that this can only be done for 30 secs! It refers to it as take off power.
IMO this is next to useless which is why I doubt it was ever used.
The ex factory Ash82 FNV spec shows it can generate 1850 hp when revs increase to 2500 and then specifies that this can only be done for 10 minutes! It refers to it as war emergency or combat power.
To sumarise ........my belief is that the use of WEP (2500 rpm) was not actually limited by an arbitary time period. It was infact limited by the engine temperature that the higher revs generated. I advocate that the air cooling system on the La5Fn was not as efficient as the La7 and so WEP duration was reduced.
Basically the way the la5FN engine was mounted and cooled it got hot quicker than the la7.
Every book written on the la5, la5f, la5fn, la7 refers to the two problems of high cockpit temperature and engine fumes and the various solutions tried to solve them. It would be a reason that La pilots usually "cruised" with the hood pulled back.
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Tilt wrote Ex factory the manifold is 1200 at 2500 rpm 20 mm could even be down to gauge accuracy or indeed supercharger wear or even incorrectly set throttle........its not a biggie.
100% correct. Combat power is 1000mm afaik, so there´s 50PS difference at best. BTW, 1180mm is the proof that it was a 1850PS engine with direct fuel injection. Russians still don´t want to believe that it was a late war engine. The difference to their specs (580km/h at sealevel with wep) is astonishing high...But where should germans know about 1180mm boost from?
There are some mistakes in the english translation of the report. The climbrate with combat power is listed at 16-17m/s instead of 16.17 in the german print. The part about the supercharger should be better translated in the following way:
"The usage of emergency power for the high altitude gear of the supercharger is forbidden"
This is confirmed by russian tests where you don´t see any wep ratings when the engine runs in the high alt gear. AH also simulates this, the engine quickly loses power. AH wep power over 3km is actually normal power in real life, but it´s ok to do it this way. Imo the compressed air was too hot in the high alt gear with wep. It probably would have produced "knock outs" (correct expression??)
The higher fuel consumption in the high alitutde gear of the supercharger also indicates that a rather rich mixture was used in this condition to produce an inner cooling effect.
niklas
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It think you are exactly right on this. RAM air can be affected by the plane's angle of attack. A poor intake design might exaggerate the problem in a climb.
-blogs
Originally posted by Tilt
WEP on the La5FN
...Rechlin also makes comment that WEP could not be used during climb...........its not clear if this refers to it not being useful (which I dont believe) or infact that it could not be used (like it was not allowed). Airflow through the engine cooling system would have been poor during climb in comparison to higher speed straight flight use.
...To sumarise ........my belief is that the use of WEP (2500 rpm) was not actually limited by an arbitary time period. It was infact limited by the engine temperature that the higher revs generated. I advocate that the air cooling system on the La5Fn was not as efficient as the La7 and so WEP duration was reduced.
Basically the way the la5FN engine was mounted and cooled it got hot quicker than the la7.
Every book written on the la5, la5f, la5fn, la7 refers to the two problems of high cockpit temperature and engine fumes and the various solutions tried to solve them. It would be a reason that La pilots usually "cruised" with the hood pulled back.
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Here's a comparison with AH and FB 1.11 (according to Youss's IL2 Compare).
(http://www.pp.htv.fi/vpitkane/la5fn.gif)
Camo
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It seems like the La5FN in the report has in fact been a damaged La5F, which didn't reach full performance. It definately was not a La5FNV, since only one experimental engine with the FNV index was produced.
I'll try to get more info.
Camo
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Originally posted by LLv34_Camouflage
It seems like the La5FN in the report has in fact been a damaged La5F, which didn't reach full performance. It definately was not a La5FNV, since only one experimental engine with the FNV index was produced.
I'll try to get more info.
Camo
There are records (Photographs) of an La5 f captured in 43........ it was tested without spinner cap which was destroyed.
But to confuse a late model direct injected engine with a boosted induction carburettor system would be very lax.
Since my posts above I found two publications (that may use the same source) that the La 5FN (V) tested at rechlin was captured in September and tested in October. Albeit that the above report is apparantly dated March 45. (I dont know where Rechlin is but would be surprised if Germany had time to concern its self with testing a 2nd line enemy aircraft in March 45)
The FNV was the only version of the Ash 82- FN (V) series produced from about April/May 44 onwards.
All but a few of the early La7's had it. La5FN production only continued into October due to a massive stock of wings at two plants and as soon as the older FN engines were used up FNV engines were installed into La 5FN (V)'s. I do not know how many but it would have differred for each plant.
We should not get too over excited about the FNV however. It was able to give out slightly more power at higher altitudes from which I read that the 2nd stage of boost gave greater potential power than the previous FN version.
We know some stuff about the Unit tested from the data above.
The machine had been in service for some time. (Design life of an La5FN was 6 months..... expected life was 4 to 5 months..... many were used longer than this.)
There was a 50kg weight imbalance that still intrigues me.
The manifold pressures at 1180 would not have produced full WEP. (this could be an error)
The limited use of WEP seems to be based upon and instruction (not permitted) rather than a technical deduction. ( I have my own theories as to why)
I read a mix of data based upon actual trials and some derived from either captured data or intelligence from captured pilots.
I wonder what octane fuel was used. The proper octane for the Ash 82 FNV was 95. Available at the time of test was B4 (87 Octane) or C3 (96 Octane) and possibly another fuel rated 92 Octane [C2?]
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Could just be the fit and finish of the plane. Russian production models (planes and engines) were notorious for a 10-20 percent slip in performance relative to test reports.
-blogs
Originally posted by LLv34_Camouflage
It seems like the La5FN in the report has in fact been a damaged La5F, which didn't reach full performance. It definately was not a La5FNV, since only one experimental engine with the FNV index was produced.
I'll try to get more info.
Camo
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Originally posted by joeblogs
Could just be the fit and finish of the plane. Russian production models (planes and engines) were notorious for a 10-20 percent slip in performance relative to test reports.
-blogs
That too........ although I would have said upto 10% slip in the main. One plant was notoriusly worse then the other...........often adding significant weight just from over use of glue!
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I am intrigued by the references and terminology used ...........
Upon extension of the slats the aileron control is said to "reduce to the point of overbalance"............. at 200 to 210 Km/hour (the period over which slats extended/retracted)
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.
This seems to indicate that there was a considerable roll mushyness between 200 and 210 Km/hour greater than that experienced both above and below that speed range.
Does this seem to fit with what would be expected?
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Originally posted by Tilt
I dont know where Rechlin is but would be surprised if Germany had time to concern its self with testing a 2nd line enemy aircraft in March 45
"A central test centre was established at Rechlin on Lake Müritz in Mecklenburg-Vorpommern, in 1933."
Lake Müritz is ~100km NNW of Berlin.
There is a museum there.
http://www.luftfahrttechnisches-museum-rechlin.de/
http://www.luftfahrttechnisches-museum-rechlin.de/html/body_englsich.html
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Gentlemen, you seems to be having problem distinguishing between two different versions of the same engine.
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.
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.
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.
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lol, bogun, always the same weak argument. Actually the FNW term was commonly used in western sources for the direct fuel injected engine. Intelligence maybe heard about the project in russia, thus when they captured the la-5FN they simply called the engine FNW.
In any case, the boost 1180mm clearly indicates that 1850PS rating was used (maybe slightly less, 1850 is 1200mm). Climbrate of 16-17m/s also indicates FNW engine, and furthermore, an engine that develops full rated power.
It was a captured aircraft, of course, and noone expect it to perform like a factory fresh one. The difference to the russian claims is extraordinary high, however, and considering the russian claims in comparison to performance claims of similar german and japanese designs, russian performance claims for serial machines become very doubtable. VERY doubtable ...
niklas
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lol nikas, always same week argument… :D
Using the term FNW on the West does not explain correct Russian engine designation M-82FNV in the original German report. 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. No wonder considering how many hour this engine had by that time. This in addition to locally manufactured engine cowling and god knows what else Germans needed to manufacture and fit on the plane after crash would explain plane being not capable of reaching its rated speed. 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.
If you remember – Lerhe was not the only one who was flying La at that time…
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Hi Tilt,
>There are records (Photographs) of an La5 f captured in 43........ it was tested without spinner cap which was destroyed.
>But to confuse a late model direct injected engine with a boosted induction carburettor system would be very lax.
Quoting Lerche:
"After the abovementioned Lancaster flights ended in August 1944, I received the message in mid-September 1944 that the first Lavochkin La 5, the well-known Russian fighter, had been acquired airworthy in Groß-Schimanen in Eastern Prussia."
Lerche also quotes the exact dates of the ferry flight to Rechlin, obviously from his surviving log book:
Take-off 15.09.1944 16:03 h
Stop at Märkisch-Friedland 17:12 h to 18:38 h
Landing at Rechlin 19:33 h
>The limited use of WEP seems to be based upon and instruction (not permitted) rather than a technical deduction. ( I have my own theories as to why)
Quoting Lerche:
"The accusation, though, that the performance of captured aircraft was understated on request by the top brass was absurd."
He mentions this right after his paragraphs on the La-5, so my theory was that the La-5 he tested was indeed performing below standard - else the frontline pilots wouldn't have doubted his findings.
>Stall data..........I wonder what weight this AC was at?
3347 kg with 80 kg for the pilot, which seems low.
>I wonder what octane fuel was used. The proper octane for the Ash 82 FNV was 95. Available at the time of test was B4 (87 Octane) or C3 (96 Octane) and possibly another fuel rated 92 Octane [C2?]
Lerche once mentions (with regard to a western type) that they kept stocks of captured aviation fuels.
Anyway, if they didn't wreck the engine with emergency power, they certainly had "enough" octane :-)
Regards,
Henning (HoHun)
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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
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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.
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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)
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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)
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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)
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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...
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(http://www.tilt.clara.net/pics/rechla5fn.jpg)
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.
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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.
(http://mitglied.lycos.de/luftwaffe1/sonstiges/M82_chart.jpg)
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)
(http://mitglied.lycos.de/luftwaffe1/sonstiges/La-Propaganda.gif)
niklas
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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)
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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)
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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)
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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.
(http://piloten.88-iap.de/sokol/la5fn.jpg)
niklas
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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)
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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
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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/
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Hi Tilt,
I just found the following quote in one of your old posts:
---cut---------------
Early La5 fns were fitted with only 3 of the 5 tanks fitted in the original La 5 this infact reduced range to circa 500Km..... with the advent of the metal sparred La5FN they introduced 4 tank set ups (2 x 168 L & 2 x 148 L) totalling 632 L . Air intake clutter at the wing roots and attempts to lighten the fuel load forced the La 7 back to 3 tanks ( 460/470 L).
---cut---------------
Since Lerche's La-5FN"V" had the 460 L tankage, does that help us to date it?
It seems it must either have been an early La-5FN with wooden wings then, or a very late La-5FN with the new La-7's wings.
The latter would fit the remark on armour thickness you made above.
Regards,
Henning (HoHun)
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Bogun , u can be wrong, in CSSR army we have to notice even each projectile ammo for the service pesonal VZ 56 , like year of fabrication, and fabrication batch serial number, for warfare that was 1000 % more strict, i know Rusian army was a very Bordelic system , what ever Soviet forces was with us on shoting range on the poligon we always have to watch out , those soliers constantly lose something , like hand granade , ammo , even the AK 47, what forst 1 soviet oficer even donot rememer where hi put hiz brand new ak 82
but last what i know about ,,high tech ,, stuf in rusian army they was wery paranoid , and that before WW2 so if the first planes showed up, i thing they kept serial traces at last that time until plane become outclased
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Originally posted by niklas
Never saw an original flight test document with detailded description.
first and last pages of 37 pages of original Russian flight test data on various la7's ............ stamped and signed.
They are scans of photocopies.......
I have them zipped in three files each of about 600kB...........
do you really want them or this this some kind of test?
(http://www.tilt.clara.net/pics/001.GIF)
.
(http://www.tilt.clara.net/pics/037.GIF)
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Hi Tilt,
>I have them zipped in three files each of about 600kB...........
Since I don't speak any Russian, that would be wasted bandwidth, but if there are any diagrams or tables that can be understood (with a bit of help :-), I'd be highly interested!
By the way, did you catch the bit about the fuel tank size? I had hoped you as our premier Lavochkin expert could use it as a help in dating Lerche's plane :-)
Regards,
Henning (HoHun)
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Originally posted by HoHun
By the way, did you catch the bit about the fuel tank size? I had hoped you as our premier Lavochkin expert could use it as a help in dating Lerche's plane :-)
Regards,
Henning (HoHun)
It does not help really...... I read recently that the Gorky plant produced so many wooden sparred wings in 43 for the La5FN. That whilst Moscow went onto metal sparred wings and subsequent la 7 production ... Gorky continued to produce la5Fn's with wooden wings up until October 44.
Hence Gorky produced the three tank la5Fn for some months after Moscow plant had switched.
I have known that Gorky continued La5FN production due to its stock of wings...........I did not know (but do now from Yefim Gordons latest work) they were all wood wings.
On this basis the wooden winged 3 tank 460 litre La5fn was always the type produced at Gorky whilst Moscow (did) and Ulan Abe may have switched to the 4 tank prior to the production of the la7 coming on stream.
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Hi Tilt,
>Gorky continued to produce la5Fn's with wooden wings up until October 44.
Thanks, I had no idea it was so complicated :-)
Does the 460 L tank volume definitely mean Lerche's La-5 was a model with wooden wings?
Regards,
Henning (HoHun)
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Originally posted by HoHun
Does the 460 L tank volume definitely mean Lerche's La-5 was a model with wooden wings?
No not definately...........the best you could argue is a "most probably"....
and we still have a 50kg wheel base mis balance.
This could be due to some thing stupid like a deflated tyre and so the lower wheel bearing more load.........I just could not believe it.
It could be that the castor wheel was not in line or the prop weight not centralised when the ac was weighed...... seems a bit basic to miss.
It could be that one wing still has an old (out of use) outer tank in it...........equally implausable.
It could be that one wing is just plain heavier than the other.....(Gorky was infamous for "filling" gaps with resin to over come poor manufacturing tolerances) but 50Kg????
I am tempted to believe that it was a combination of some of the above...The La's did not carry out of axis components like the spit or the 109 (except for the pitot) and so should be balanced. Hence the prop not quite centre, the castor over to one side, a tyre slightly deflated, a little more glue etc.
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The russians still today seem to be totally unaware of the rampant corruption, misinformation and abuse their whole system had (and partly still has.)
Any negative reports meant a trip to a gulag or even a shot in the back of the neck. The reports were surprisingly good. :rofl
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A question, Tilt.
The quote Hohun dug up:
Early La5 fns were fitted with only 3 of the 5 tanks fitted in the original La 5 this infact reduced range to circa 500Km..... with the advent of the metal sparred La5FN they introduced 4 tank set ups (2 x 168 L & 2 x 148 L) totalling 632 L . Air intake clutter at the wing roots and attempts to lighten the fuel load forced the La 7 back to 3 tanks ( 460/470 L).
seems to contradict what you have written in your own La-5FN site(http://www.btinternet.com/~fulltilt/deshist.html#La-5FN) where it states:
However through out 1943 and 1944 the La-5 FN benefited from a continued weight saving program as certain wooden parts were replaced with light alloy parts. The fuel tanks were later changed to a 4 tank set ( when the metal sparred wings were adopted) but this did not add to the aircrafts range which had been reduced by the heavier breathing engine. Combat mission flight duration at full power was now only 40 minutes, however this could be extended to 2 hours and 32 minutes when at reduced engine revs of 1600rpm.
So am I missing something here? Got me confused :)
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Originally posted by Kweassa
So am I missing something here? Got me confused :)
No Kweassa I think I am.
I need to check my notes but the range comparison is with that of the earlier 5 tank la5f and my site did not make that clear.
Basically Lavochkin was under continued pressure to bring range back to that of the earlier type.
Very little data (ie next to none) is available to me regarding the 4 tank set.
Its possible that Gorky never produced such a 4 tank la5Fn and it was done at either Moscow or more likly somewhere like Tblisi (Georgia) which was a small, comparatively well resourced but initially inexperienced plant (it later produced the bulk of the 3 cannon la7's that saw service) This is just speculation.
I would speculate with some confidence that the 4 tank la5fn was a rare beast as it was almost certainly not produced at Gorky and if produced at Moscow would have stopped as soon as La7 production kicked in. Again note this is speculation.
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Originally posted by Tilt
and we still have a 50kg wheel base mis balance.
edited: misunderstood question
Don´t forget that a weigth difference on the outside of the wing can produce a larger difference on the wheels. It´s momentum question. additional 10kg on the outside of a wing can give you easily this difference. Radio mounted offside. Speed indicator tube etc.
niklas
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Thanks for the answer, Tilt. But I have some more questions popping up my head :)
So, from what I learned from this excellent thread(and assume :D ), the differences in the early models of the La-5FN and the latter model is as follows:
1) early La-5FNs had their WEP limited, while later models, due to better cowling design and construction process, had their WEP effectivity and longetivity increased.
2) early La-5FNs had 3 fuel tanks, while later models had four, accompanying the change to metallic wings.
3) Due to the difference in fuel tank number, the early La-5FN had a flight range circa. 500km, while the later versions had more than 600km.
Can the above sum it up adequately?
I also have some serious of smaller questions, in that case.
1) Is the increase in WEP performance, purely from the cowling design alone?
2) I know you've stated it once, but it seems the difference in performance is never really clarified, between the earlier and later La-5FNs. Is there any documental proof referring that there was a difference in performance between the two?
3) With the promise that I'm not gonna hold the numbers to you, nor will I comment it elsewhere lightly without your permission :) , if there isn't a really clear indication of difference in performance documented on paper, what would your expectation of the differing performance be, between the early and later models? Especially considering the speed performance at sea level and maximum speed at altitude?
4) What would be the first thing you'd look at, if you see a La-5FN externally, internally and performance wise, without documented tecbnical data on paper, that you could use to differentiate the earlier version and the latter?
To tell you the truth, :) I'm into a small discussion with a group of people about the La-5FN modelled in IL-2/FB. It's not one of those "big" discussions in UBI forums or something, just a small disagreement around my squad mates who are all Koreans, and in our small, private forum.
I'm convinced that the La-5FN modelled in FB is that of 1944, on the grounds of performance(which closely matches our AH La-5FN), WEP duration, and listed range in the object viewer. If there was a typical simulated plane as in the games we play(thus, we have info on speed/climb performance, internal cockpit modelling, exterior 3D modelling, but no official confirmation from the developers), what would be the major points to verify that La-5FN's date of service? :)
Also, if you have tried FB, or have any data on the La-5FN modelled there, I'd really appreciate it if you gave your expert opinion :) I'd also appreciate any other input.. Hohun? Niklas? Anyone ?? :)
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Originally posted by Kweassa
Thanks for the answer, Tilt. But I have some more questions popping up my head :)
So, from what I learned from this excellent thread(and assume :D ), the differences in the early models of the La-5FN and the latter model is as follows:
1) early La-5FNs had their WEP limited, while later models, due to better cowling design and construction process, had their WEP effectivity and longetivity increased.
My view. I have more data indicating(suggesting) that the la5fn had engine temperature management issues that limited the wep duration than i have data that actually confirms that WEP @2500 was as available on the la5Fn as it was on the La7.
If we are to accept this then it is for all La5fn's as it is a function of cowling and air flow design around the engine that was never modified on the La5fn.
The problem is that hard data pertaining only to the La5fn is hard to find in abundance. Rechlin suggests it. Czech pilots flying in 44 mentioned it. I have one set of Russian curves (which were originally produced for a magazine article) that state it. I would love some VVS test results that confirm it.
Hence if asked an opinion I would sugest that the la5fn did not have access to the length of wep duration the la7 had. If you ask me for fact then I hesitate.
2) early La-5FNs had 3 fuel tanks, while later models had four, accompanying the change to metallic wings.
i think the correct statement would be that some late 43/early44 models had the 4 tank set. The bulk of the La5Fn's would have had the 3 tank set even those produced at Gorky till Oct 44.
3) Due to the difference in fuel tank number, the early La-5FN had a flight range circa. 500km, while the later versions had more than 600km.
Again its better not to draw a line in time to say before this date 3 tanks and after this date 4 tanks. However it seems that the 4 tank La5fn had the same range as the 5 tank la5f.... i will check the actual range when I get home but think "more than 600" to be a safe phrase.
1) Is the increase in WEP performance, purely from the cowling design alone?
la7 exhaust tubes were re routed to improve air flow between the rear cylinders.
La7 spinner was shaped to improve air flow into the forward engine chamber.
La7 upper cylinder engine air flow was not displaced by the supercharger intake duct dropping behind the rear upper cylinders like the La5fn. Both had to accomadate the cannon barrels however.
re cowling
La5fn cowling had more hinge points and was not as close fitting as the La7. La5fn cowling was not a full 360 degree affair with air loss to the bottom where it profiled the oil cooler. further it was not a perfect cylinder when properly fitted (it had a bulged middle) hence good fit and seal was difficult along the hinge and join lines.
2) I know you've stated it once, but it seems the difference in performance is never really clarified, between the earlier and later La-5FNs. Is there any documental proof referring that there was a difference in performance between the two?
Yes there is. It is expressed in terms of "x" kilometers/hour below those figures gained from development model. I will dig them up for you. Basically the history shows that initial production machines were significantly below what was expected and this was latterly corrected.
3) With the promise that I'm not gonna hold the numbers to you, nor will I comment it elsewhere lightly without your permission :) , if there isn't a really clear indication of difference in performance documented on paper, what would your expectation of the differing performance be, between the early and later models? Especially considering the speed performance at sea level and maximum speed at altitude?
see above
4) What would be the first thing you'd look at, if you see a La-5FN externally, internally and performance wise, without documented tecbnical data on paper, that you could use to differentiate the earlier version and the latter?
virtually no external indicators unless you had the production number and could place it close to some published AC with known production numbers and date of production.
A few ac from the first batch may have some clues from the type of radio mast used (vertical or forward leaning) forward leaning being the std adopted.
The use of a small cockpit air inlet forward and below the front screen would suggest it is not one of the first batch (but this could have been retro fitted.)
If it is carrying the Fn rhomboid insignia then it is not from the 1st batch. Some of which even had the old la5f circular insignia still on them.
But these last three indicators identify a (comparatively)small group of AC rushed out of production in early 43 to put in the front line around Kursk. I say comparatively because when production was put into full swing at Gorky this one plant alone was producing several hundred a month by October 43.
What would be the major points to verify that La-5FN's date of service? :)
Unfortunately I would say its all up weight and performance would be the best indicators. (the very things you would wish to cross reference). Fuel tanks aside the la5fn got marginally lighter as it was developed on a production basis. This is really the adoption of lighter metal components in place of wood. The all metal spar being a significant improvement.
The next problem is slotting these developments into the best time frame. Its fairly safe to say the La5fn optimum was achieved by early 44. However we have to understand that components were never discarded......production was king. If you had 1000 wings of an older design they were used regardless of the benefits of the newer wings now in production at another plant.
Hence you could argue that eg Moscow plant had optimised performance by Nov 43 (with a metal spar even) whilst Gorky never had the advantage of the lighter wing even when it ceased production in Oct 44. So which model do you adopt for your FM? As Gorky was the biggest producer by far this would be the safe bet and Gorky was able to continue lightening the AC (in other areas) even after Moscow had wholly switched production to la7's by May/June 44. So it does not mean that Gorky produced AC were held to a 43 standard in all aspects.
To grasp this understanding further you have to step out of the "western" view of ac production and into a GPW Russian one.
The Lavochkins and Yaks were produced in a regime that considered the life expectancy of such fighter aircraft to be of just a few months (between 3 and 5). Hence we see what are actually "throw away" aircraft being produced in significant numbers under massive production pressure from the State.
I am sure that somewhere in Russia now are some original VVS test figures which Maddox may have had access to. The problem with all such data is that as soon as Maddox or HTC show their sources they open them up to copying by competitors or a level of critique from their players (and competitors) that is avoided by a higher level of confidentiality. Its obvious to me that there is a certain amount of "filling in the blanks" with some AC FM's where data is missing. I am usually very impressed to see how well the blanks are filled when the data is laterly discovered.
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Thank you for the detailed response! It's helping me understand the plane smuch better. :) I appreciate the effort and time you put into the answers, and also thank you advance for the "numbers digging"!! :) :)
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It seems there is a way to date the \la5Fn if you can see the radio wires.
Early units used the same wire pattern as the la5f with two wires from the top of the tail post one of which went to the bottom of the mast the other to the top.
The bulk of the production units had both wires from the tail post leading and joining at the top of the mast with an extra wire dropping to a fuselage spigot. As per early La7's.
Very late production units had this last extra wire dropping to a spigot on the rear cockpit glass. This is post la7 commencing production so would be Gorky units from June 44 onwards.
other notes
Forget my reference to tblisi it only made a few la5FN's in 43 (5). I need to cross reference some other stuff before confirming it.
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Hi everyone,
here's more information about captured Lavochkins:
http://pub157.ezboard.com/fluftwaffeexperten71774frm62.showMessage?topicID=2.topic
Regards,
Henning (HoHun)
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Hi guys: great discussion going on here!
I've been away for quite awhile with the arrival of a new 2 month old and thought I would pop my head in here to see what was going on. Between him and his brother they've evened the odds out at our household 1 to 1 between parents and kids! This is my first opportunity to think about things aerodynamic in a long time hehe.
Nice to see some good flight performance and specific aircraft technical discussions going on here! Very intelligent posts by all involved starting with F4UDOA on down.
I think HoHun does a nice summation of the analysis of the data.
The conclusion to draw from this is that Lerche's test aircraft had a significantly higher coefficient of drag than the Tsagi test aircraft.
The cowling theory HoHun brings up is really interesting in contributing to drag of the aircraft. Another similar factor that could be at play as well is the condition of the aircraft itself. Quoting from the original doc posted by F4U...
The aircraft itself was fully serviceable. Its flying hours are not known bu the machine has been in service for some time. Surface finish, especially that of the wings (wood) is good;
Joeblogs and Tilt's comments touch on this a bit regarding production model VVS aircraft. Multiply that by the "machine being in service for some time"- e.g. fairings no longer sealed well, cowling issues etc. could result in the drag differential we're seeing at max level speeds? Something to think about.
Also do we know if compressibility correction is applied to the Tsagi max speed data?
I'm also puzzled by the WEP comment in the document. Joeblogs and Tilt postulated on the effect of ram air cooling (or lack there of) impacting the inability to reach WEP ratings. What strikes as even odder is the statement about not being able to attain WEP in horizontal flight as well.
I agree with HoHun's statement...
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.
Tango, XO
412th FS Braunco Mustangs
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Hi everyone,
>The 8-... designation is an RLM habit - every aircraft (and engine, and propeller ...) seems to have had an 8- designation for some reason. This doesn't give away the version, though.
After having read Edwin Black's "IBM and the Holocaust", I'd say it could be that the "8" of the RLM designation was some punch card code for aviation hardware.
I'd speculate that the RLM also administered stuff with different codes, like "1" for uniforms, "2" for ground vehicles etc.
Regards,
Henning (HoHun)
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Originally posted by HoHun
Hi everyone,
>The 8-... designation is an RLM habit - every aircraft (and engine, and propeller ...) seems to have had an 8- designation for some reason. This doesn't give away the version, though.
After having read Edwin Black's "IBM and the Holocaust", I'd say it could be that the "8" of the RLM designation was some punch card code for aviation hardware.
I'd speculate that the RLM also administered stuff with different codes, like "1" for uniforms, "2" for ground vehicles etc.
Regards,
Henning (HoHun)
The RLM prefix code for re-action propulsion engines was 109, was it not? This was sometimes shortened to just a 9 it seems.
Do any know what all the prefix codes used by the RLM are?
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Hi Tilt,
>The statement re WEP again (for me) confuses the use of WEP in the La 5FN (V). I have other documents that infer that its WEP was not of the duration that could be used on the La7 (Albeit for earlier La5FN models.) And only safely used for 2 mins.
>However this quotes the manifold pressure at 2500rpm at 1180......I thought it was higher than this at 2500rpm (1200 ). Indeed at 2600 rpm the pilots notes claim that manifold should be 1260 but his could only be used at take of for no more than 30 secs!
There's a German performance curve for the M-82FNV that shows 2500 rpm, 1.63 ata = 1199 mm Hg yielding 1850 HP at sea level (could be 1.68 ata = 1235 mm Hg). It's labeled "Start" (take-off) and only to be used to up to of 300 m (I suspect that's without ram effect), which looks like close to the full throttle height for that setting.
There's also a M-82 curve on the same page, which seems to indicate that the M-82 had the same supercharger gearing for the high gear at least. The data on another page confirms that the gearing is the same for both gears, actually. Still, the Tsagi climb graphs for the La-5FN seem to indicate that the graphed performance was reached with an engine with lower high gear supercharger ratio, which I assume was the M-82FN.
>One was an Article by Alexyenko and Kondratiev that had been translated. I do not know the credentials of either.
>Another were a couple of Czech articles.
>In an out of print book called "In the cockpit" there is an article written consulting two Czech pilots who flew La5FN's.
>They refer to 2500 rpm "take off power" that could only be used for 2 minutes.......
Very interesting. Note that Lerche states that full emergency power cannot be reached in the capture La-5FNV as the engine doesn't develop full boost. Maybe that's part of the explanation why it didn't perform correctly - I'll have to revisit the climb performance to check the power again.
>We then look at the development criteria for the La7 and we see the cowling was subject to considerable work. Not only for external steam lining but also with respect to internal air flow.
Squadron/Signal "La-5/La-7 fighters in Action" mentions that the relocated oil cooler on the La-5 "206" (similar to La-7 position) improved air flow through the cooler by 35%.
By the way, do you know the propeller diameters for the La-5FN respectively the La-7? I haven't found these yet.
Regards,
Henning (HoHun)
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There was a 50kg weight imbalance that still intrigues me.
I am by no means an expert on VVS A/C. I was doing some research on the FW-190 and came across some interesting features which could explain the 50Kg balance.
Many WWII A/C placed the Oxygen tanks in the wing. If the VVS used a high pressure tank (compressed O2), continuos flow regulator system then that would explain the weight. This was the most common Oxygen system for the Allies until late in the war.
The Germans did not use compressed O2 in their oxygen delivery systems. They used Liquid Oxygen in small high pressure spherical cylinders. Very similar to a "Power Tank" if any of you go 4 wheeling.
The compressed O2 high pressure tanks would have been larger and heavier. 50 Kg is probably about right to balance it out 3-4 steel High Pressure gas cylinders.
Crumpp
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Hi Tilt,
>Note that Lerche states that full emergency power cannot be reached in the captured La-5FNV as the engine doesn't develop full boost
I should have added "in high superharger gear" here.
>I'll have to revisit the climb performance to check the power again.
From a quick comparison of the Tsagi La-5FN (1943) data, it seems like they used full emergency power for the speed graph, but some 100 HP less for the than that for the climb graph. Of course, that La-5FN (1943) probably was powered by an Ash-82FN (not the FNV I'm using for comparison with the captured La-5FNV), and unfortunately I don't have a power curve for the Ash-82FN.
Regards,
Henning (HoHun)
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Normal WEP for La-5FN, La-7 was 2500 rpm, 1180 mm hg. Its manual and test data.
I should have added "in high superharger gear" here.
This is not a bug - this is feature ;).
"Then using supercharger second speed - do not allow manifold pressure higher than 1000 mm hg to avoid detonation..."
Its from La-5FN manual.
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Voodoo (I think) is correct.
Pre detonation is a function of overheating..so inadequate head cooling would have limited the use of higher powers......particularly during climb.............infact at level speeds over cooling was also a problem.
2500 rpm was only used to augment power in the lower supercharger gear...........infact the higher gear did not bring any benefit (or could not be used for other reasons) below circa 14,000 ft ( this would vary by a few hundred feet as to whether the ac was in climb or level at speed [ram effect again])
The oxygen bottle is central in the fuselage it was there for the pilot to breath. Compressed air tank was also centrally stored.
The only out of balance systems were the pitot and the flap actuating cylinder which would have acounted for no more than a few kgs.
The most likely out of balance force would have been an uneven fuel load. Wing tanks drained through non return valves to the central fuselage tank............. I can see no governing system to ensure they both drain evenly (although there is a fuel valve on the cockpit floor of unknown functionality). Hence G forces could have effected the balance of drain............but 50kgs still seems a lot even for this phenomenom.
I too struggle to find the diameter of the la5 prop (same as Lagg3)......I know the La7 prop. I know its longer than the la5 prop I know the gear is 120mm longer on the La7 to compensate for the longer prop.
The only dif between the FNV and the FN (that I know of) was the 2nd stage super charger speed. (other than the later addition of a true MP/RPM governor)
The oil cooler design was more efficient and so could be (and was) made smaller. The poor pilot on the other hand was troubled with "hot feet" by the hot oil pipes bolted directly under the cockpit floor.
Its the improve ment in the engine cowling and exhaust system that allowed cooling air to be better distributed across all (and in particular the upper) cylinders that (I believe) would acount for longer use of WEP on the La7.
Voodoo do you have access to an La5FN manual?
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The higher speed of the SC at hi-gear at given altitude and air temperature causes warmer charge and throttling of the engine (to keep MAP down) heats charge even more => detonation at lower MAP than the SC at lo-gear.
gripen
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http://www.airwar.ru/other/bibl/la5fn.zip
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Originally posted by VooDoo
http://www.airwar.ru/other/bibl/la5fn.zip
Superb!........I can see endless hours with my Russian dictionary ahead
Thank you very much
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I hope that you'll notice all other stuff ;)
http://www.airwar.ru/other/bibl/il2rle.zip
http://www.airwar.ru/other/bibl/la5manual.zip
http://www.airwar.ru/other/bibl/lagg3rle.zip
http://www.airwar.ru/other/bibl/tu2man.zip
http://www.airwar.ru/other/bibl/yak3.zip
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The oxygen bottle is central in the fuselage it was there for the pilot to breath. Compressed air tank was also centrally stored.
Are you sure about this? The Germans used both fuselage and wing Oxygen storage not only depending on the TYPE of fighter but also the Sub-varient. So it is possible to find with the Bf-109 series, sub-varients which mounted wing O2 storage tanks and other which had fuselage tanks.
Maybe the VVS did the same. Do you know what type of O2 system they used.
There are so many unknown factors about VVS A/C that it is hard to seperate the fact from the fiction.
Thanks Tilt!
Great thread BTW. I'm learning quite a bit about the La series!
Crumpp
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Originally posted by VooDoo
I hope that you'll notice all other stuff ;)
http://www.airwar.ru/other/bibl/tu2man.zip
Do you know the location of a cockpit layout for the Tu2?
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:confused: Its 6-7-8 pages of the manual.
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Hi Voodoo,
>"Then using supercharger second speed - do not allow manifold pressure higher than 1000 mm hg to avoid detonation..."
>Its from La-5FN manual.
Thanks! :-)
Is there anything in the manual indicating that full 1200 mm Hg can't be used in initial climb? The Tsagi climb chart seems to indicate that instead of 1850 HP, only 1725 HP were used.
Regards,
Henning (HoHun)
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Hi Tilt,
>this would vary by a few hundred feet as to whether the ac was in climb or level at speed [ram effect again]
Do you have any data on the amount of altitude variation introduced by ram effect?
>but 50kgs still seems a lot even for this phenomenom.
Remember it's not really mass what we're talking about but torque. A smaller weight difference near the wing tip can suffice to provide the observed difference in scale readings. If the aircraft had wooden wings, which were subject to some weight variation, that might be the explanation we're looking for.
>I too struggle to find the diameter of the la5 prop (same as Lagg3)......I know the La7 prop. I know its longer than the la5 prop I know the gear is 120mm longer on the La7 to compensate for the longer prop.
Roger that. I've found a mention of a 3 m propeller now.
>The only dif between the FNV and the FN (that I know of) was the 2nd stage super charger speed. (other than the later addition of a true MP/RPM governor)
Do you have the actual ratios? I found it surprising to see that the Ash-82F and the Ash-82FNV have the same supercharger gear ratios according to a German document.
Regards,
Henning (HoHun)
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Hi Tilt,
>Do you have any data on the amount of altitude variation introduced by ram effect?
I looked at your site, and you have :-)
The data confuses me a bit. It seems the La-7 got about 1 m/s of extra climb from its larger propeller, but that the gain from ram wasn't as large for both types as I had assumed.
Regards,
Henning (HoHun)
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Hi again,
Looking at the Tsagi data, it seems that the La-5 gets nowhere near the same benefit from ram effect as the La-5FN or the La-7.
I assume this shows the success of the La-5FN's redesigned air intake.
What I've been unable to determine was the difference between the La-5 and the La-5F as the engine data quoted in various sources seems to be identical for the Ash-82A of the former and the Ash-82F of the latter.
However, as the Squadron/Signal book quotes the La-5 top speed as 509 km/h, I assume that this must be without the use of WEP.
Accordingly, I'd assume that the distinguishing characteristic of the La-5F with the Ash-82F was the capability to actually use WEP, which would be no surprise since the "F" stands for the Russian term used for WEP :-)
Regards,
Henning (HoHun)
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Sure the latter is not the ASH-82FN? Specs on that engine are considerably better. I think you know that already...
-Blogs
Originally posted by HoHun
Hi again,
Looking at the Tsagi data, it seems that the La-5 gets nowhere near the same benefit from ram effect as the La-5FN or the La-7.
I assume this shows the success of the La-5FN's redesigned air intake.
What I've been unable to determine was the difference between the La-5 and the La-5F as the engine data quoted in various sources seems to be identical for the Ash-82A of the former and the Ash-82F of the latter.
However, as the Squadron/Signal book quotes the La-5 top speed as 509 km/h, I assume that this must be without the use of WEP.
Accordingly, I'd assume that the distinguishing characteristic of the La-5F with the Ash-82F was the capability to actually use WEP, which would be no surprise since the "F" stands for the Russian term used for WEP :-)
Regards,
Henning (HoHun)
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Is there anything in the manual indicating that full 1200 mm Hg can't be used in initial climb? The Tsagi climb chart seems to indicate that instead of 1850 HP, only 1725 HP were used.
Regards,
Henning (HoHun)
65. At altitude of 100-150 (one hundred) meters set nominal settings if forsazh setting was used on take-off and you dont need it any more.
And some more things...
69. Dont use supercharger second speed while using take-off settings no matter of the flying altitude.
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@HoHun
Have you found propeller types & diameters for La-5/7?
This source
source (http://wunderwaffe.narod.ru/Magazine/AirWar/70/14.htm) states that ViSH-105V-4 were being installed on La-7, and gives the diameter roughly as 3.1 meters. Dunno whether this will help you or not :confused:
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Hi Dankes,
>This source
source (http://wunderwaffe.narod.ru/Magazine/AirWar/70/14.htm) states that ViSH-105V-4 were being installed on La-7, and gives the diameter roughly as 3.1 meters.
Thanks! I had found ca. 3.0 m for the La-5FN, so ca. 3.1 m for the La-7 makes very good sense :-)
Regards,
Henning (HoHun)
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Originally posted by Mister Fork
It's one of the diamonds in the rough... :D
I don't fly the plane..
Does it have the wing slats referred to in the report? I assume the slates are leading edge ala the 109s....
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F4UDOA:
Great post and find. Which board(s) are you venturing? I had been on the allaboutwarfare boards to find info like that but with that being shutdown didn't know what other sources existed. I'd be interested since I'm looking for some prop data.
Thanks!
Tango, XO
412th FS Braunco Mustangs
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Hi everyone,
Here's my current picture of Lavochkin history, picking the main versions though there were more and transient versions, too:
La-5 (ASh-82A):
- carburetor
- 1.29 ata/2400 rpm
- high rear fuselage
- 580 km/h @ 5.8 km (Tsagi chart)
- 14/17.5 m/s @ sea level (Tsagi chart, Normal/Forzash)
- 3360 kg
- introduction 9/1942
La-5F (ASh-82F):
- carburetor
- 1.36 ata/2400 rpm
- low rear fuselage
- 580 km/h/590 km/h @ 6.1 km (Tsagi charts)
- introduction 3/1943
La-5FN (ASh-82FN):
- fuel injection
- individual exhaust jets for greater thrust
- improved cowl for reduced drag
- improved air intake for greater ram effect
- improved control surfaces for better manoeuvrability
- 3290 kg
- 635 km/h/640 km/h @ 6.2 km (Tsagi charts)
- 17/22 m/s @ sea level (Tsagi charts Normal/Forzash)
- introduction: 7/1943
La-5FN (ASh-82FNV):
- different supercharger gearing (?)
- introduction: ?
La-7 (ASh-82FNV):
- improved aerodynamics for reduced drag
- improved radiator for greater effectiveness
- 3240 kg
- 675 km/h @ 6.1 km/670 @ 5.9 km/660 km/h @ 6 km (Tsagi charts)
- 17.5/22.7 m/s @ sea level (Tsagi charts Normal/Forzash)
- introduction 6/1944
I've mostly relied on Tsagi charts and on Squadron/Signal "La 5/7 Fighters in Action", as well as on what I learned here on this board :-)
Any comments? That's only a rough sketch so far.
Regards,
Henning (HoHun)
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F4UDOA. Great post. :)
If you find one on the La-7, please share it. I'm betting it'll say, "OMG...THE LA-7 IS UBER! We should surrender on all fronts immediately! So UbEr!"
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Originally posted by F4UDOA
Here is a report of the La-5 captured by the Germans.
The report by the Luftwaffe Test Pilot Hans-Werner Lerche, posted at the start of this thread comes from his book.
The book contains the full report posted at the start of this thread and the authors description of flying captured aircraft while at the Luftwaffe Test Centre at Rechlin, including the B-17, B-26, B-24, the P-39, P-47, P-51, the La-5 and Yak 3, and the Tempest. It is a very interesting book and an enjoyable read. It was first published in 1977 as "Testpilot and Beutefugzeugen" and the English translation is detailed below:
Book title: Luftwaffe Test Pilot, flying captured aircraft of World War 2
Author: Hans-Werner Lerche
Published by: Jane's Publishing Company Ltd 1980
ISBN: 0 7106 0031 3
Not sure if it is still in print, I picked up my copy second hand some years ago, but the details I've posted should at least enable anyone to search the used book shelves.
Good luck...
Badboy
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Originally posted by Karnak
Like all aircraft in AH it lacks the individual quirks such as not being able to use WEP in a climb, the poor oxogen system or the fumes in the cockpit.
Just thinking that...
1) HTC could code the LA-5 to lose WEP once the a/c is put into a climb at a given rate.
2) The La-5 pilot could start to pass out at altitudes higher than 11,000 ft. due to the lack of proper oxygen supply.
I wonder if HT has this book. Little intricacies, like these, might make things interesting in AH2.
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Dtango
,
I was on the all about warfare as well. Sucks that it closed.
I have found some things from unusual sources. I do searches on PROCAT docs from the British Air Ministry as well as TAIC. I have a few more up my sleave. I have the American D-9 evaluation (Not that great), the original A6M2 test as well as AAF and Navy test of the A6M5 in comparison to Army and Navy birds. P-47D4 vrs 190A4 and some others.
I collect Pilots Operating handbooks as well.
If you are looking for something specific let me know. Here is one page with lots of good docs to search.
Rings Procat page (http://prodocs.netfirms.com/)
TBoltA10,
Thanks, I do have the La-7 report from the VVS. It is also on Tilts webpage. He is the expert on VVS A/C as far as I can tell. Here is the link. The full report is in here somewhere. If you can't find it start a post in the A/C and Vehicles section with your email and I will send it to you.
He has many interesting comparisons on his site as well.
Tilts Web page (http://www.btinternet.com/~fulltilt/Perform.html)
BTW, can't forget my own page as well.
F4UDOA (Marks) webpage (http://home.comcast.net/~markw4/)
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Originally posted by TBolt A-10
Just thinking that...
1) HTC could code the LA-5 to lose WEP once the a/c is put into a climb at a given rate.
2) The La-5 pilot could start to pass out at altitudes higher than 11,000 ft. due to the lack of proper oxygen supply.
I wonder if HT has this book. Little intricacies, like these, might make things interesting in AH2.
Certainly would make it interesting of the LA5 couldn't go above 11k due to oxygen problem. Of course that would probably play better in a scenario. Enact that in the MA and there would be howling... or no one would fly the La5 any more.
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Originally posted by TBolt A-10
2) The La-5 pilot could start to pass out at altitudes higher than 11,000 ft. due to the lack of proper oxygen supply.
Lavochkins carried oxygen bottles. I do not know how sophisticated the breathing apparatus was but its existance is amatter of record>
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Originally posted by HoHun
Hi everyone,
Here's my current picture of Lavochkin history, picking the main versions though there were more and transient versions, too:
Henning (HoHun)
Its a good `summary Ho Hun. I think the only aspect that blends across some of the La5F's up until the last La5FN's is the introduction of 1st a metal wing spar and latterly a metal wing inner structures. This combined with eventual standardisation of fuel tanks.
Plus the La5FN introduced latterly rod linkages for some control planes rather than cable