Author Topic: La7 (Read 2492 times)

funkedup · « **Reply #30 on:** September 21, 2001, 12:54:00 AM »

Tilt I'm sure the m.p. ratings were the same, but even with the same m.p. limits you can get a higher full throttle altitude (and more power above full throttle altitude) if the induction inlet and ducting is more efficient.

[ 09-21-2001: Message edited by: funkedup ]

Tilt · « **Reply #31 on:** September 21, 2001, 03:50:00 AM »

Quote

Originally posted by HoHun:
Hi Tilt,
here's some data for comparison:
Henning (HoHun)

Ho Hun I can categorically state that they both had the same engine and that both delivered the same power at the prop (per throttle and manifold setting) upto at least 14,500ft (prior to 2nd stage of boost when the V type incurred an advantage).

We should also remember that the La 7 had a new prop that was only fitted to a very (comparatively)few La5FN's.

Re funked's point I can only say what the max power settings were at various rpm with various levels of boost. Given that the prop pitch would be set (manually in the case of the La5FN)to maximise the use of the available power then thrust is only a function of prop design....(with a little bit of exhaust thrown in)

Can you please direct me to an authentic La5FN chart that shows a WEP curve.

I confirm a bench setting of 10 mins at 2500rpm for 1850hp on the Ash82FNV. I have just never seen a VVS curve for the La5FN showing it.

Incidently on the bench rating the Ash82FNV could be run at sea level at 2600 rpm for up to 60 seconds at (i think) about 2000hp. I do not believe this was permitted in flight.

Climb rates IMHO were only marginally improved and only significantly improved under WEP, so this would agree with your theory.

Incidently it has always been my impression that a fully WEP'd D9 would out accelerate and be faster than an La7 at most altitudes above sea level. What it(the d9) could never do was out climb it(the La7)

Tilt

niklas · « **Reply #32 on:** September 21, 2001, 06:18:00 AM »

Quote

The Fw 190A-8 achieved a 578 km/h top speed at sea level using 1800 HP. The Fw 190D-9 achieved 612 km/h at 1900 HP.

Not correct Hohun.
The A8 reaches 578km/h with 2000PS (1,62ata), The D-9 612 km/h with 2100PS
Tank himself reached with the D-9 583km/h near ground, when he used normal emergency power, 1750PS.

niklas

HoHun · « **Reply #33 on:** September 21, 2001, 10:02:00 AM »

Hi Tilt,

>Climb rates IMHO were only marginally improved and only significantly improved under WEP, so this would agree with your theory.

Thanks, that does indeed point towards unchanged engine power. Do you happen to have climb information for the La 5FN similar to the La 7 information on your website?

>Can you please direct me to an authentic La5FN chart that shows a WEP curve.

I won't judge its authenticity, but have a look at

http://www.kolumbus.fi/latesoft/tsagi_charts.html

One of these charts shows a La 5FN (1943) with a 10 min WEP duration at low altitude.

It also shows two different La 7 versions.

>Ho Hun I can categorically state that they both had the same engine and that both delivered the same power at the prop (per throttle and manifold setting) upto at least 14,500ft (prior to 2nd stage of boost when the V type incurred an advantage).

I'd say Lavochkin did an exceptional job at streamlining the La 7 then.

My comparison to the Fw 190 was flawed since I had assumed too little power for the Fw 190A-8 - my BMW801 engine graph showed only 1800 HP WEP at sea level, but at a lower boost than quoted by Niklas.

However, I'm certain the D-9 was capable of the aforementioned 612 km/h at sea level with just 1900 HP (running with B4 fuel and Ladedrucksteigerungsrüstsatz), so that its increase in speed actually coinceded with a decrease in power. In other words, I had underestimated the Focke-Wulf's drag reduction for my comparison with that of the Lavochkin.

Regards,

Henning (HoHun)

Eaglecz · « **Reply #34 on:** September 21, 2001, 10:56:00 AM »

Wow Check how this one looks !

http://www.btinternet.com/~fulltilt/pl_02.jpg

isnt his Flag pretty ?

and greeeeeen colour .. ummmmmmm

Tilt · « **Reply #35 on:** September 21, 2001, 07:46:00 PM »

>Thanks, that does indeed point towards unchanged engine power. Do you happen to have climb information for the La 5FN similar to the La 7 information on your website?

Not as full as for the la7 with different rates under WEP etc... but one Tsagi reference at 5.1 minutes and several texts at 5.00 and 5.1 mins to 5000metres

>Can you please direct me to an authentic La5FN chart that shows a WEP curve.

>I won't judge its authenticity, but have a look at

>One of these charts shows a La 5FN (1943) with a 10 min WEP duration at low altitude.

I eat my words and it does look authentic although much later than the war years in publication. Who's is it? I want to get permission to use it?

>It also shows two different La 7 versions.

I have some problems with pic 3 on several items...What do you think of the 109K curve?

>I'd say Lavochkin did an exceptional job at streamlining the La 7 then.

The la5FN left considerable work outstanding the streamling was the work of Tsagi not Lavochkin

Did you notice the WEP less yaks?

Tilt

Tilt · « **Reply #36 on:** September 21, 2001, 08:01:00 PM »

Quote

Originally posted by EagleC:
Wow Check how this one looks !

Well czech this one out it was actually part of a La5FN Czech regiment fighting behind the lines in Slovakia during 44.

RENE

Unfortunately the la7's were only given to Czechaslovakia after the war when the Czech insignia was added.

Tilt

juzz · « **Reply #37 on:** September 22, 2001, 01:07:00 AM »

"In conclusion and added to to other data re round weight, size and explosive content (which Vermillion used to have on his web site) I would venture that the Shvak 20 (99r)had better range and lethality at target then the 151/20 (82)"

If the information on this page regarding ShVAK ammo is accurate, I would not say that the Soviet gun would be more lethal than the MG 151/20. Especially if you consider that an M-Geschoss round has about 3 times the explosive content of the ShVAK HE round.

HoHun · « **Reply #38 on:** September 22, 2001, 09:04:00 AM »

Hi Tilt,

>I eat my words and it does look authentic although much later than the war years in publication. Who's is it? I want to get permission to use it?

Browse back to a thread named "Tsagi Charts", there's the original URL given - with the hint that it's a bit slow, that's why I selected the other one.

>>It also shows two different La 7 versions.

>I have some problems with pic 3 on several items...What do you think of the 109K curve?

The fat black line roughly matches the Messerschmitt graphs for a Me 109K-4 with DB605D at Steig- und Kampfleistung (climb and combat power). With "dry" WEP it was about 20 km/h faster, but the speed gain with "wet" WEP (MW50 injection) would have been considerable.

According to Griehl, the Me 109K was capable of 530 km/h @ 0 m and 700 km/h @ 8000 m on dry WEP, the values increasing to 608 km/h @ 0 m and 728 km/h @ 8000 m. The Tsagi chart more or less matches these values, except having the 728 km/h at a (more logical) 6000 m altitude.

The comment "1 - 3 min only" doesn't seem to be quite correct, though, using MW50 with the DB605 was cleared for multiple 10 min bursts (and in combat often was applied continuously).

>The la5FN left considerable work outstanding the streamling was the work of Tsagi not Lavochkin

That's quite interesting! Here's some more detail on La 5 engine history:

"In 1942 most of these technical innovations [created by the MiG OKB for the radial-engined MiG-3 developement I-210/I-211] (engine cowling design and airtightness, proper positioning of the engine istself, and the I-210 wing leading edge slats) were passed on - at the order of the Narkovmavprom (state commissariat of the aircraft industry) - to the Lavochkin OKB, which adapted them successfully to the La-5, a mass-produced fighter."

(Belyakov/Marmin, "MiG - 50 Years of Secret Aircraft Design")

Regards,

Henning (HoHun)

Tilt · « **Reply #39 on:** September 22, 2001, 12:46:00 PM »

Quote

Originally posted by juzz:
" Especially if you consider that an M-Geschoss round has about 3 times the explosive content of the ShVAK HE round.

Ok there may be a debate about lethality at target...the Germans obviously prefered the high explosive thin shell variant to the Russians "fragmentation shell" approach and vice versa. There is a long debate on the conversion of potential chemical energy to actual damage. (Whats better a small grenade or a bigger stick of TNT?)

Whats is undeniable is the greater muzzle velocity, higher kinetic energy, higher RPM (plus better aerodynamics) of the Svak fired 99rx20. Hence I would presume that the effective active range and time to target of the Shvak munition to favour it in air combat over the 151/20.

Contrary wise I recognise that the M-geschoss 82x 20 upon exploding in certain critical internal areas would exert more damage than the 99rx20.

A neat site tho thx for finding it............ the only coment I would make is that most other texts do not agree that the b20 was reliable. It seems to have been quite unreliable in comparison to the Shvak.

Tilt

juzz · « **Reply #40 on:** September 22, 2001, 08:37:00 PM »

According to the Russian Aviation Musuem, this is how they went from the La-5FN to the La-7.

La-5FN "206", TsAGI modified La-5FN.

La-5FN "Model 1944", Lavochkin modified La-5FN based on TsAGI modifications but able to be mass-produced.

Then came the La-7.

[ 09-22-2001: Message edited by: juzz ]

niklas · « **Reply #41 on:** September 23, 2001, 04:13:00 AM »

i saved this pic some month ago (forgot the source)

Darkglam · « **Reply #42 on:** September 24, 2001, 03:26:00 PM »

En mi opinion el G10 es superior al La 7 si lo lleva un experten(SUPONGO pej). Para un piloto de nivel medio el La 7 le da mejores resultados en la relación derribos/muertes. Y lo que dice el del P-38 de las bajas velocidades, pues el mismo y su mecanismo.

Entre 5k y 15k el La 7 es un monstruo y tiene poder de fuego muy bueno a menos de 275yardas. Recordad que en AH (MA) hay pocos combates a mas de 20K.

Una escuadra de La-7 trabajando en equipo seria terrible.

A mi el avión que más me está sorprendiendo ultimamente en AH es el 205, nunca pensé que la indusrtria aeronautica italiana hubiera fabricado un avión tan peligrosillo.

niklas · « **Reply #43 on:** September 25, 2001, 03:23:00 AM »

Quote

Originally posted by HoHun:
Another graph even shows the La 7 (no engine variant mentioned) with 630 km/h sea level top speed.

It´s interesting to see that the russian aviation museum website lists the La-5 "206" with 630km/h, too.
Is the La-6 "206" identical to the La-7 mentioned in some sources where they list 630km/h topspeed? It almost looks like a La-7.

niklas

MANDOBLE · « **Reply #44 on:** September 25, 2001, 05:18:00 AM »

Darkglam, put another experten in the La7 and pray for the G10.
The G10 has good characteristics to flee from a La7 but not to kill it.
The La7 will set up a hi speed medium-lo level fight where the G10 has no chances to touch it. To kill effectivelly, the G10 needs to slow down the combat, else it is a flying rock, G10 is not adecuate for a high speed fight. In the other hand, planes like D9, P51, F4U (IMO, best plane against La7) or Thyph are well suited for a hi speed duel against a La7.

Darkglam, el G10 es demasiado torpe a altas velocidades como para enfrentarse a un La7, a no ser que el piloto del La7 sea un novato que sepa poco mas que hacer giritos. El G10 quizá sea el mejor avión para huir de un La7, pero no para cazarlo. Para ello necesitas un avión que tenga un excelente control a altas velocidades, como puedan ser el D9, P51, F4U o el Typh. En mi opinión, el mejor para cazar al La en un duelo a alta velocidad es el F4U (C o D).