Author Topic: La7 ..how does it rate ? (Read 1238 times)

Dingy · « **Reply #15 on:** February 05, 2001, 11:31:00 AM »

Hmmmm...dunno about your La5 but mine fights pretty well up to 15K. Anything higher, I just bait em down to my level

Higher than 15K, Verms right...its tough to do much.

-Ding

leonid · « **Reply #16 on:** February 05, 2001, 11:55:00 AM »

Actually, there are better times than that for climb and turn rates for the La-7. However, there are also those times for some serial production La-7s. For example, a serial production La-7 posted a time of 4.65min(nominal)/4.30(WEP) minutes to climb to 5000m in April '45. This same aircraft also had sustained turn rates from 18.5-19.5 sec at 1000m. OTOH, another serial La-7 in July '45 posted a sustained turn rate from 20.7-21.2 sec at 1000m. So, there

leonid · « **Reply #17 on:** February 05, 2001, 12:05:00 PM »

Documents from the Scientific Test Institute, Soviet Air Force (NII VVS) tested a Bf109G-4 against a La-7. Their conclusions were that the La-7 had an obvious advantage over the G-4 in vertical maneuverability up to 3500m. However, it also retained equal vertical maneuverability with the G-4 up to 6500-7000m.

Vermillion · « **Reply #18 on:** February 05, 2001, 12:31:00 PM »

Nimitz, it comes down to the quality of each countries supercharger/turbosupercharger technology.

The higher you go, the better performance you need to keep up the boost in the engine. And to make a high quality supercharger/turbosupercharger you need very high quality production and machining, and you need some very high quality components, for instance bearings and high temp steel.

IMO, both the Japanese and the Soviets had a generally poor quality of supercharger technology, the Germans were moderate in this area (but the best in rocketry and jet engines), while the British and the Americans generally in the highest category. And when it comes to turbosuperchargers, the most expensive and difficult to build, I believe only the Americans deployed them in significant numbers (please correct me if I'm wrong here).

Soviet engines of the era, where very rugged reliable, and cheap to build in quantity, but used the "brute force" theory of engineering. In simple words, their engines had some of the highest displacement to horsepower ratio of any of the combatants.

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Vermillion
**MOL**, Men of Leisure

funked · « **Reply #19 on:** February 05, 2001, 02:26:00 PM »

Re: Performance Variation
The M-82FN had a large difference between normal power (1470 hp) and augmented power (1850 hp). In the Gordon & Khazanov books they mention that some of the climb tests and vertical maneuverability tests were conducted at normal power.

Re: Power Loss at High Altitude.
The M-82FN had a single-stage blower. The more effective engines at high altitude (Merlin, P&W R 2800) had either a turbo or a second stage that kicked in at high altitude. A second stage is quite complicated mechanically, requires redesign of engine installation, and is going to add weight and size. The turbo raises manufacturing issues (high temperature alloys) and the installation basically requires that you design the plane around it, like the P-38 or P-47.

With a single stage blower you can only increase the performance at altitude by driving the blower faster or putting in a bigger blower. A bigger blower means more weight and a redesign of the engine installation with resultant packaging issues. Driving the blower faster means you will have net power loss at lower altitudes where the power required to drive the blower faster is less than the power generated by the higher boost pressure. The Soviets wisely chose to optimize the performance under 15,000 feet, where all the action was on the Ostfront.

[This message has been edited by funked (edited 02-05-2001).]

Seeker · « **Reply #20 on:** February 09, 2001, 09:53:00 AM »

Intersting stuff, especialy for a newbie, we don't have the LA7 in Airwarrior.

We do, however, have the La-5 and Yak.

You may like to drop by a friends site:
http://www.btinternet.com/~fulltilt/Lavochkin.html

leonid · « **Reply #21 on:** February 09, 2001, 01:04:00 PM »

Nice site, Seeker

Westy · « **Reply #22 on:** February 09, 2001, 01:57:00 PM »

A very excellent web site. Thanks Seeker.

-Westy

Fariz · « **Reply #23 on:** February 14, 2001, 09:09:00 PM »

Yes, it is a close match to yak-9u, but it shall be slightly better on verticals and slightly worse on turns. Most important is that it has better punch and more ammo than yak-9u.

RAM · « **Reply #24 on:** February 14, 2001, 09:44:00 PM »

from the link provided by seeker:

"The standard La 7 had a top speed of 592km/h at sea level - 46 km/h more than the La5fn and 72km/h faster than the Focke Wulf Fw190A-3............

The La 7 was also 15km/h faster than the Focke Wulf Fw190A-8, the latest version of this German fighter deployed on the Eastern front. With a take of weight of 3240 kg the La7 was about 1060 kgs lighter than the Fw190A-8.

Seeker, please give us the source of that information. AH's La5FN speed on the deck is greater than Fw190A8's and according to this, Fw190A8 should be 30kms/h aprox FASTER than La5FN, and only 15km/h less than La7

[This message has been edited by RAM (edited 02-14-2001).]

Sorrow[S=A] · « **Reply #25 on:** February 15, 2001, 02:09:00 AM »

IIRC RAM those last numbers would be referring to sea level speeds not the top speeds at altitude. To Soviets SL speed was much more important.

niklas · « **Reply #26 on:** February 15, 2001, 02:14:00 AM »

Quote

Seeker, please give us the source of that information. AH's La5FN speed on the deck is greater than Fw190A8's and according to this, Fw190A8 should be 30kms/h aprox FASTER than La5FN, and only 15km/h less than La7

A La5 with M82FNW (FNV) engine was tested in Rechlin. It had a topspeed near ground of 520km/h with emergency power.
climbperfomance with normal power 16-17m/s near sealevel.

niklas

RAM · « **Reply #27 on:** February 15, 2001, 02:31:00 AM »

Quote

Originally posted by Sorrow[S=A]:
IIRC RAM those last numbers would be referring to sea level speeds not the top speeds at altitude. To Soviets SL speed was much more important.

I read there that ALL those speeds listed are at sea level, Sorrow.

Quote

The standard La 7 had a top speed of 592km/h at sea level - 46 km/h more than the La5fn and 72km/h faster than the Focke Wulf Fw190A-3............

The La 7 was also 15km/h faster than the Focke Wulf Fw190A-8, the latest version of this German fighter deployed on the Eastern front. With a take of weight of 3240 kg the La7 was about 1060 kgs lighter than the Fw190A-8.

I read here that the SL speed of the La7 was 10mph (16km/h) faster than the Fw190A8 aprox...and I have seen lots of references that talk of Fw190A8s making 360mph on the deck. This information matches the 360mph number quite exactly.

The current Fw190A8 in AH does 350mph on the deck only...see what I mean?

[This message has been edited by RAM (edited 02-15-2001).]

RAM · « **Reply #28 on:** February 15, 2001, 02:45:00 AM »

BTW; according to the charts, La5FN does near 360mph on the deck...well, that quote says especifically that La5FN was 46km/hour SLOWER than La7 at SL, and that Fw190A8 was 15km/h Slower than La7...so 30km/hour FASTER than La5FN.

According to that page's info La5FN should be making 340Mph at SL, wich is ALMOST IDENTICAL to Fw190A5's SL speed!!!!

So I am a bit lost here, wich are the accurate numbers?...the ones in that page or the ones in the AH charts?. 20mph is quite a BIG discrepance, frankly.

And, well I dont know about La5fn, but I have read several books listing Fw190A8 speed at 360mph on the deck. Why is only 350mph in AH?.

[This message has been edited by RAM (edited 02-15-2001).]

leonid · « **Reply #29 on:** February 15, 2001, 03:16:00 AM »

RAM,
Flight data is nothing but the recorded parameters of individual aircraft, and not all aircraft are created equal. VVS aircraft could have wide ranges of speeds sometimes for a given variant, and was usually due to production quality. I have data of a 1945 serial La-7 that did 383mph @ SL, but you will also find data of other serial La-7s that have slower speeds, or inferior performances. Test data of captured aircraft could be even more inaccurate, since the quality of the aircraft might be questionable. Captured aircraft didn't usually come with an operating manual, so that left those testing the aircraft with a lot of guesswork. Hence, maximum performance could be difficult to attain. So, how fast was a La7? From what I read about them they were the only VVS fighter able to catch up with a Fw190A in a dive. In AH I know it is very difficult to catch up with a Fw190A while flying a La-5FN or Yak-9U. At best, you will do no better than slowly creep up on a 190A, and only during an extended level run.

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leonid, Kompol
5 GIAP VVS-KA, Knights

"Our cause is just. The enemy will be crushed. Victory will be ours."

[This message has been edited by leonid (edited 02-15-2001).]