ShVAK vs. MG-151

[leonid]

Decided to move the discussion from "Russians & IJN/IJA factories on strike. how much longer??" over to this forum as it seemed more appropriate ...

I put a La-5FN otr, then zoomed forward view to maximum setting.  Next, cannons were fired and the dispersion of rounds was measured with a ruler on the screen.  The same exact thing was done with a Bf 109G-6, firing only MG-151 cannon.  And, yes, convergence was identical at 250 yds. to keep all test conditions identical.  The resultant dispersion from the ShVAK cannons and MG-151 was the same at about a 3/8" spread on the screen.

Next, I measured glass reflectors of the gunsights on both the La-5FN and Bf 109G-6 under maximum zoom.  It was found that the Bf 109G-6's gunsights had an extra 6/8" of glass below the bullseye than the La-5FN's.

Finally, a strafing test was done by both aircraft, following similar runs along the same slope at A1 while pulling slight Gs.  The Bf 109 went first, and where the dust was kicked up was marked on the screen.  Next, the La-5FN went and it was immediately noticed that the mark on the screen for the Bf109's hits were below the glass reflector of the La-5FN's gunsight, and when the La-5FN was put through the run it's hits were only just noticable along the bottom of the glass relector.

In conclusion, what appears to be a drop in velocity is actually an optical 'trick' or effect due to the different sizes of the gunsights and the very restricted forward viewing that the La-5FN possesses.  Thus, the evidence compels me to believe that the ShVAK is modelled correctly.

I might add that historically the limited forward vision of a LA-5FN was a common complaint among VVS pilots, and it was a concern of mine as I waited for somebody to model it.


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leonid, Komandir
5 GIAP VVS RKKA

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

[juzz]

Now where's that La-7 with better forward visibility and three cannon?  

[-aper-]

Leonid
I can only say that I had no problems swithing from Bf-109 to C205 (I flew C205 for about 1 month in beta2 tour). And I had big problems with deflection angles after switching to La-5FN. IMHO La-5FN seems to be equiped with something like MG-FF but not ShVak.

[Oleg Maddox]

 

Originally posted by juzz:
Now where's that La-7 with better forward visibility and three cannon?  

La-7 had two main weapon modifications. Most mass was with two cannons.

About what is La-5FN or La-7 in good hands please read a bit here 4th replay  http://www.dogfighter.com/ubb/Forum6/HTML/000007.html

[juzz]

What little info I have on the La-7 armament states that Moscow production was with two ShVAK cannon, and Yaroslavl production had the three B-20 cannon. But, shhhh - we want three cannon!  

PS: Can we fly the La-5FN and La-7 in Il-2, or is it only the LaGG-3 that's flyable?

[leonid]

juzz,

If you have an interest in Sturmovik go to this forum.

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leonid, Komandir
5 GIAP VVS RKKA

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

[Sorrow[S=A]]

Wow oleg, thanks for replying!
It's very sepecial to see someone from another game dev team stop by here.

BTW have you flown the La-5FN in AH, what was your opinion of it?

[-lynx-]

Guys - read Soviet Combat Aicraft of WW2 by Gordon and Khazanov    . (Thanks a million Verm - it's finally arrived and it's a beauty!)

La7 was a leap forward from already dangerous La5FN with improved forward visibility (engine air intake pipe moved to wings from the top of cowling) and manoeuverability.

During front line testing by 63rd Guard Fighter Air Corps 30 La7 flew 462 missions with 55 kills to 4 La7 lost in combat. And that's with just 2 ShVAKs...

Pilots complained about insufficient firepower and 3 B20 were fitted from 1945 on all La7s. On the other hand - La5FN "1944 standard" were rolling off the factories with 3 B20s in 1944... That's where we are in in AH, right?

Soviet highest scoring ace Ivan Kozhedub (62 victories in La5FN/La7) flying La7 shot down Walter Schuck (206 victories) in his 262...

Captain Skomorokhov (46 victories) chased, caught (!!!) and killed a 190 making off at full speed (AGL apparently) and that was his 3rd 190 in that sortie.

Bring them on HTC!

p.s I wonder if anyone could help me here:

La5 (AH) expends all ammo in 17 secs giving rate of fire of 705 rpm/gun. Since they were synchronized cannons (850 rpm non-sync) I can't work this rate of fire into 3 bladed 2,600 rpm prop. Can anyone explain to me how this works? Thanks.

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-lynx-
13 Sqn RAF

[This message has been edited by -lynx- (edited 04-22-2000).]

[This message has been edited by -lynx- (edited 04-22-2000).]

[This message has been edited by -lynx- (edited 04-22-2000).]

[leonid]

WRT using the ShVAK, I have to say that many of my kills are very close (100-200yds), and that many of them are below the air intake.  In fact, I often don't see the target itself when firing under G's.  The less-than-perfect Z-buffering helps with this, as does the overhead icon, but many times they do not.  One could say that if you shoot enough in a La-5FN and you'll just know where the rounds are going, eventually.  Or you don't.  For me, I do.  Maybe, it's because I'm right-brained  


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leonid, Komandir
5 GIAP VVS RKKA

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

[Vermillion]

Glad you like it Lynx  

FYI the La5FN "1944 standard" was actually the prototype aircraft for and was later redesignated to the La-7.

If I remember right Juzz is correct on the armament options. Initially one factory didn't want to disrupt production with the new B-20's (plus the overall lack of the new cannon), while the other factory used them from the start. I think that by 1945, both factories were using the 3 cannon B-20 setup. But I will let the true experts step in here and give a definitive answer.

Regardless, AH should include both setups as an armament option.



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Vermillion
**MOL**, Men of Leisure
Carpe Jugulum
"Real Men fly Radials, Nancy Boys fly Spitfires"

[Sorrow[S=A]]

Yep verm- the standard of 1944 plane was Lachovin's sneaky way of showing his plane could meet the standards required of the war ministry for production. In reality it was only a prototype to compete against the Yak-3, which met the requirements by weakening the airframe to make it lighter, Lach OTOH lightened his plane other ways and made it more aerodynamic in a primitive wind tunnel experiment. Gee I wonder why pilots much preferred the La?  

 In any case when he got permission to build the La-7 design the original factory continued with the twin ShVAK as it was allready proven and the factory tooled for it. The B-20 had several reliability problems in field testing and needed more cooling solutions. Eventually the second La-7 factory produced B-20 versions but I believe the original produced the ShVAK right up to the end of the war.

Both _should_ be an option in the La-7. The B-20 version should be 5 mph slower due to drag from the gun casing and cooling projections. The ShVAK version should be about 150 lb's heavier due to the heavier guns and lack of a disintegrating chain ammunition supply. Also La-7 should have 15% less fuel, however should feature a 5 tank fuel supply that was better at self sealing than the La-5 or -5FN.

Also interesting was a few notes Oleg made on his own UBB. almost ALL soviet planes were capable of using rockets as a field armament. The russian design featured a re-usable rack the held 3 to a wing, in the field these were attached by means of a screw in 4 places to the underside of the wing and fired by a simple electric lead which was _allready_ plumbed to the cockpit by the factory. ie if you need rockets your mechanic screwed the rack to the wing and fished around the middle hole until he grabbed the lead and hooked it up. Thus the La-5FN and La-7 should actually have the option to have rockets, if not listed as a factory option they were an often added field modification.

[juzz]

 

Towards the end of production in 1944 a very few fighters had steel wing spars and duralumin webs, though retaining ply covering, and these were often called La-5FN/41. Production terminated at about 9,920 aircraft in October 1944.

By this time all four factories had gradually been changing over to a fighter based on the La-5 but given sufficient improvements to warrant the new designation La-7. The major difference lay in the adoption of the new wing also used in the La-5/41, aerodynamically almost unchanged apart from further refinement to the ailerons and slats, but with a substantial proportion of metal in its structure.

TsAGI had carried out a detailed study of drag-reduction modifications for the La-5FN, and these were also incorporated, including improved main-wheel bays with doors, a straight wing leading edge; restoration of tailwheel retraction(often omitted on La-5s); relocation of the oil coolerin a more efficient duct under the trailing edge; substitution of leading edge root inlets for the dorsal engine air inlet; removal of the Hucks starter dogs on the propellor shaft; a new engine cowl opened in two giant left/right 180º panels; and new armament. It had been planned to fit three of the light B-20 cannon, but only Yaraslavl-built La-7s had these new guns, Moscow production having two or three of the heavy ShVAKS.

I missed the "or three" part the first time I read that.  

[Sorrow[S=A]]

Yikes!

I would think that would make the plane a bit nose heavy! hehe. They couldn't have possibly put 200 rnds apiece ammo if they had three of those things in there!

[leonid]

Sorrow,
There was 150 rounds apiece for the B-20s, which is a max of 450 rounds, 50 more than the 400  for the two ShVAKs.

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leonid, Komandir
5 GIAP VVS RKKA

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

[Sorrow[S=A]]

Yes, I knew the B-20 loadout..  but I never saw anything on a tri ShVAK cannon loadout. I assume it was mounted like the B-20's were. But there just can't have been much room, the ShVAK used a solid chain infeed, worked great had almost no jam's. But took up room, I wonder how much ammo a triple cannon plane would have had. Or I wonder if late war ShVAK had a disintegrating chain infeed designed for them :?