Yak-7B performance

[JtD]

In the last update it was said that the new FM of the Yak-7 will be accurate to within 5km/h of historical data. This leads to the question - what is the historical performance. Looking into my sources I really didn't find a lot and losing all bookmarks gives me no starting place for a search on the net.

 

All suitable info I found is a chart in the TsAGI-book which compares typical 1942 with typical 1943 performance. Unfortunately, this lacks all details and does not include high altitude performance (which is the aspect I'm most interested in). There are also some figures in Gordon/Khazanov, but they do not appear to be relevant for a series 36 aircraft.

 

Does anyone have any particulars on the Yak-7B series 36?

 

[Guest deleted@50488]

Well,

 

and looking at that graph it looks like all Yaks are, after all, inferior to either the LagG3 ( 1943 versions ) less between around 1500m and 1800m, and above ~3800m, where the Yak-7b becomes clearly advantageous ( ? )

 

Also, both the Me 109 F-1 and G-4 are way better at higher alts ( above ~5000m ) ?

 

So, I wonder what will really make the difference ? The maneuverability at lower alts ? The armament ?

[Panthera]

Should be noted that the 109G4 is a lot faster down low than what is presented on that chart, reaching about 535 km/h @ SL at 1.3ata, and 550 km/h at 1.42ata.

Edited January 28, 2018 by Panthera

[ShamrockOneFive]

Tough to track any details down about the Yak-7B much less the Series 36.

 

We did get some details from Black Six in this thread: https://forum.il2sturmovik.com/topic/31037-yak1b/

 

There's also some very basic details on this page: http://www.airpages.ru/eng/ru/yak7.shtml

 

What I understand is that the Yak-7B Series 36 is a late production model and probably the last of the line before they started putting bubble canopies on and then not too much longer before they started calling them Yak-9. So I'm expecting that the performance will line up fairly close to the Yak-1B Series 127, obviously with some differences too on account of weight and slightly different aerodynamics and structure. It's going to be a lot better than the Yak-7B that we have in IL-2: 1946.

 

This site has some interesting info as well: http://ram-home.com/ram-old/yak-7b-m105pf.html

Edited January 29, 2018 by ShamrockOneFive

[JtD]

Thank you. Interesting to read, but as with other sources, it lacks the specifics. Hard to anticipate what we'll be getting.

 

Do we know if our Yak is from the Novosibirsk factory (the better of the two)?

Edited January 29, 2018 by JtD

[ShamrockOneFive]

Thank you. Interesting to read, but as with other sources, it lacks the specifics. Hard to anticipate what we'll be getting.

 

Do we know if our Yak is from the Novosibirsk factory (the better of the two)?

 

Run into the same problem. Everywhere I go there are bits and pieces of information but definitely a lack of specifics. I'm sure the devs have some original documentation.

 

Not sure where our Yak-7B is coming from. Thing is even the sources on the performance discrepancy might be not entirely accurate. I'm taking it at its word but sometimes these things are just oft repeated myths though I know that factories produced varying qualities of aircraft.

 

No idea.

[GridiroN]

According to wikipedia (I know...) the Yak-7B offered increased maneuverability and strongers firepower over the s69 Yaks. So you know how you're re-entering Earth's atmosphere in your 109, coming down on a Yak you spotted minding his own business and all of a sudden he starts break-dancing on the deck and you curse the Soviet aviation board's name for commissioning such an aircraft?

 

Yea, it'll be even more annoying. And less forgiving on opponents as if it gets an advantage, it has dual berezins now instead of rifle cals. On a serious note, though I think it's performance in all areas is supposed to be better than the Yak 1 s69 but not quite as good as the Yak 1B s127.

 

That's what I'm expecting. It was also apparently available for combat quite early, so It will be interesting to see if map makers make it available for maps beside 1943 Kuban. Same with the P39.

[Sgt_Joch]

This is from Gordon, Khazanov "Soviet combat aircraft"

 

yak-7b has the same engine as the in game Yak-1/1b, but is 110-150 kg heavier.

 

1. test of Yak-7B, series 22, late 42:

 

-test weight: 3010 kg

-speed at SL: 514 kmh

-speed at 3.6 km: 570 kmh

-climb time to 5 km: 5.8 minutes.

 

the basic model stayed the same, but there were improvements to the manufacturing/finishing of the aircraft.

 

2 . test of Yak-7B, series ?, early 43:

 

-test weight: 3048 kg

-speed at SL: 547 kmh

-speed at 4 km: 612 kmh

-climb time to 5 km: 4.7 minutes.

 

performance figures on the 2nd test seem a bit on the high side to me, since that is better performance than tests of the Yak-1b. I expect Yak-7b performance ingame will probably be similar to the Yak-1 or somewhere between the Yak-1 and Yak-1b

Edited January 31, 2018 by Sgt_Joch

[JtD]

If I interpret the text on page 55 correctly, these figures come from a OKB, LII, NIIVVS, TsAGI modified test aircraft 3101 and aren't representative for service conditions. Not sure, though.

[Sgt_Joch]

that would make sense, Gordon, Khazanov mention that series 41 was 22-25 kmh faster than series 22, which pretty much matches up with the performance of the Yak-1b

[tomo-pauk]

In the last update it was said that the new FM of the Yak-7 will be accurate to within 5km/h of historical data. This leads to the question - what is the historical performance. Looking into my sources I really didn't find a lot and losing all bookmarks gives me no starting place for a search on the net.

 

All suitable info I found is a chart in the TsAGI-book which compares typical 1942 with typical 1943 performance. Unfortunately, this lacks all details and does not include high altitude performance (which is the aspect I'm most interested in). There are also some figures in Gordon/Khazanov, but they do not appear to be relevant for a series 36 aircraft.

 

Does anyone have any particulars on the Yak-7B series 36?

 

The improvements in speed figures on that chart are, as specified in the book, a result of improved fit & finish. The hi-alt performance can be extrapolated, it looks like 100 km/h disadvantage vs. Bf 109G at 8 km for examples produced in mid-1943, and even worse for examples produced in 1942.

[bivalov]

speed of "Yak-7B 1943" at low-middle altitude is almost same with speed of real Yak-7B s36 - https://forum.il2sturmovik.com/topic/28867-lets-talk-about-yak-7b/?do=findComment&comment=463907

so, speed at >3700 meters also will be very similar

 

PS btw, Leonid Khrushchev, son of Nikita Khrushchev, piloted and MIA 11.3.43 exactly on Yak-7B s36

 

Edited March 4, 2018 by bivalov

[Bilbo_Baggins]

So the figures are out.

 

My question is how does the Yak 7b manage 526kmh vs Yak 1 69's 514kmh with the same engine?

 

Wasn't the Yak 7b, if anything, more draggy than a series 69?

 

Cheers

[ShamrockOneFive]

So the figures are out.

 

My question is how does the Yak 7b manage 526kmh vs Yak 1 69's 514kmh with the same engine?

 

Wasn't the Yak 7b, if anything, more draggy than a series 69?

 

Cheers

 

The Yak-7B we're getting is a more refined design than the earlier versions. So I'm guessing that, like the Yak-1B, it has a better propeller and airframe improvements that make it less draggy.

[-=PHX=-SuperEtendard]

So the figures are out.

 

My question is how does the Yak 7b manage 526kmh vs Yak 1 69's 514kmh with the same engine?

 

Wasn't the Yak 7b, if anything, more draggy than a series 69?

 

Cheers

 

 

The Yak-7B we're getting is a more refined design than the earlier versions. So I'm guessing that, like the Yak-1B, it has a better propeller and airframe improvements that make it less draggy.

One noticeable change is the retractable tailwheel for example.