La 7 Weights

[Tilt]

test flight weights for la7 built during 1944 varied.

and not all the test data I have was at full ammo or full fuel.

Despite having a capacity of 200 rpg the tests seem to have been done on differing ac at 170rpg.

Also start fuel on these trials varied between 442 and 450 litres. Although the max capacity was 460 litres.

This generates test flight weights varying between 3230 and 3235 kgs.

However by averaging it out and using AH rnd weights and 6lb/gal for the extra fuel we see the following.



Modified data 1944 460 litres 2 x 200rpg minus pilot = 7182 lbs

Aces High 1944 460 litres 2 x 200rpg inc. pilot = 7385 lbs

If an AH pilot is 200lbs and given that the recorded data varies by 10kg (22lbs) that seems pretty good to me.

At the end of 44 (december) La7's seemed to start to get heavier. This may be due to additional work done on the manifold ducts in the wing roots (filters and flaps) or indeed the intrinsic fuselage weight gained thru increased use of formaldihyde glue (this occurred on the La5FN too as some production lines would use copiuos ammounts regardless of the weight penalty)

However from late dec 44 la7's are consistantly weighing in between 3265kg and 3275 kg . I also have two post war la7's (3 cannon) weighing in at 3310 and 3312 kg. (and this extra weight is not due to the extra cannon!!)

By doing similar maths based to the above plus factoring in 3 x B20's @150rpg instead of 2 x shvaks @200rpg.


Modified data 1945 460 litres 3 x 150rpg minus pilot = 7240 lbs

Aces High 1945 460 litres 3 x 150rpg inc. pilot = 7390 lbs

Now our AH pilot only weighs 150lbs.

Looking at the figures AH seems to have the 1944 la7  just about spot on re weight.

The 3 cannon model was made in 1945 however. In 1945 the default airframe plus equipment was heavier.

So even though the 3 x Bereznins did not increase the weight over the 2 x Shvak they were used when the airframe had got heavier.

Hence you cannot take the 1944 weight and simply do the 2 x shvak > 3 x B20 maths to arrive at the  weight of the 3 cannon model. You should also factor in that the 3 cannon model was a heavier 1945 variant.

Based upon the AH 1944 2 x shvak being correct. (7385lbs)

In my opinion the  AH early 1945 3 x berezin should start with full fuel and ammo (no ordinance) heavier than we now enjoy. (closer to 7440 lbs)

[Krusty]

The 3-gun was rare. Don't forget that MOST La-7s, throughout 1944 and through 1945, had the 2x shvak. So you can't just say the 2-gun option is from early 44. It's probably a late-44 variant (or even '45??) in Aces High regardless of which guns package you choose. Which would mean that it's too light (?) when taking the 2-gun option, I think (???).


EDIT: To further narrow it down, look at the engine and performance data and find which real-war variant closely matches it. That will let you know if it was late '44 or not.

Edit2: I mean look at the engines instead of the weight. The weight could be off, depending on the performance it gives

[Tilt]

Yes HTC could consider the 2 gun to also be a 45 variant. Then the AH 2 gun weight data may be some what incorrect too.

Actually all the test data differs by small amounts for the various ac tested over 44 to 45. Its not an exact analysis.

No.45210150 a 2 x shvak ac was recorded at 582 Km/hr on the deck (non WEP) in August/sept 44. (no WEP top speed taken) weighed  3234 kg with445 litres of fuel and 340 rounds of ammo.

No.45213276 a  2 x shvak ac was recorded at 580 Km/hr on the deck (non WEP) in May/June 45. (616km/hr with WEP ) weighed  3275 kg with445 litres of fuel and 340 rounds of ammo.

No.38102663 a  3 x Berezin ac was recorded at 579 Km/hr on the deck (non WEP) in May/June 45. (613km/hr with WEP ) weighed  3315 kg with 433 litres of fuel and 390 rounds of ammo.

Please note these are "quality control records" not type specifying trials.

You will note that the performance re top speed of the 44/45 2 gun models are equitable in deed they all are.

However if we look at climb to 5000 metres its a different matter.

Frame number  / No WEP time  / With WEP time

No.45210150  / 4.95mins/4.55mins

No.45213276 / 4.65mins /4.3 mins

No.38102663 / 5.25 mins / no data.

All La7's made at plant 21 (likr the 1st two above) had the 2 x Shvak gun package. Plant 381 bagan producing the 3 gun package in February 45 after which it only produced the 3  gun package.

The 3 gun package did not really begin to arrive at the front lines until late March 45.

Plant 21 (gorky) was the main plant for La7 production. However whilst the few hundred La7 3 gun packages that saw service were "uncommon" it would be misleading to refer to their number as rare.

As I said at the beginning. AH's data seems to be a very good fit (in fact the best fit) for No.45210150  in terms of weight and approx performance.  

Where AH data is too light for No.45213276 .Plus assuming that the 2 gun package is the 1944 La7 gives it a slot in Scenarios from Bagration onwards whilst the 3 cannon would only see action over Germany ,Czechia and later Manchuria. (plus alittle bit of action at Konigsberg and Courland)

[Viking]

Also consider that in AH the fuel might be lighter per gallon than the real deal in Russia. Especially if the tests were done in winter.

[Krusty]

Tilt, those numbers imply that the engine changed somewhat in the later models (if the weight is nearly identical but the climb increased).

According to Gonzo's page, the La-7 in AH does 359 on mil power at 500 feet. That's only 3mph slower than 580 kmh (362mph). That's less than 1% different, and well within normal variations from aircraft to aircraft. It's harder to judge time-to-alt with a climb chart, though. How fast does the AH LA-7 climb to 15,000 feet, with and without WEP?

[Tilt]

There is extensive data on No.45213276 .............

It was fitted with a hydraulically controlled dust filter which was used during take off and landing. This was added virtually at the wars end as the La7 engine was sufferring from dust pick uo thru the wing root intakes during the dry spirng of 45.

this plus a superior cockpit vent system may have counted for its extra 40Kg weight.

anyway............... i was only comparing weights....its clear that there were variation between aircraft tested and some IMO may have been brought upto 100% spec whilst others were tested with faults. Have one account of test data with a slat stuck out!

for info

No.45213276

[Krusty]

Well, that was Soviet QA... if it doesn't work, throw it into the meat grinder, along with 500,000 more of the same, and eventually you'll clog the enemy guns and the last Soviet person left will kill the Germans with a hoe, rake, or shovel.


(*yes, yes, I know... bad Krusty, bad.... but they had such poor regard for life that I'm not far off!*)

[bj229r]

Originally posted by Krusty
Well, that was Soviet QA... if it doesn't work, throw it into the meat grinder, along with 500,000 more of the same, and eventually you'll clog the enemy guns and the last Soviet person left will kill the Germans with a hoe, rake, or shovel.


(*yes, yes, I know... bad Krusty, bad.... but they had such poor regard for life that I'm not far off!*)

Heh, I read a book by Guy Sajer (cant remember title)---kid was a Belgian conscript into German army, spent YEARS on eastern front, and managed to live. He said the Russians would send cannon fodder across minefields to make the mines explode, thus making way for the competent soldiers with the bullets....how do you fight such an enemy?

[Stoney74]

Originally posted by bj229r
how do you fight such an enemy?

Invent an atomic bomb...