AH's Lavochkins

[Westy]

 note this was something a friend allowed me to post here. I think he's got some good points and I would love to see if this garners any reponse from the HTC folks. I'd love to hear others opinions as well. Here were his observations and questions -Westy

• The Lavochkin's could only trim elevator and rudder from the cockpit.

Aeleron trim was with respect to physically bending a metal aeleron tab
on one wing.

• Lavochkins did not have independant wheel brakes.
• WEP on the  AH La5FN last's too long. Whilst the Ash82 could be

independantly driven at 2500 rpm for some time when placed in the
La5FN cowling and wrapped with its exhaust system the engine over
heated quite quickly (2 minutes). I note there is a temperature
guage but do not see it effect performance through over use of
WEP (on the La's)

• The flaps were split and hydraulically driven to a maximum deflection

of 60 degrees. Whilst the pilot "could" feather the flaps it would be
more practical to use them as 2 stage flaps. Whilst not advocating
AW's "instant" flap they would be quicker than AH's seem to be (are
all AH flaps bast on an servo driven model?)

• Cockpit Forward view:  Even from the default viewing position the

central armoured window was much larger (than AH's) and the sight
fills it with its target point higher (than AH's).  I do not think
that the cowling was visible in the La 7 in the same way as the
supercharger intake was in the La5FN

 http://www.tilt.clara.net/White77/cockpit.html

• Cockpit Rear views: The AH armoured glass panel is more restrictive

to viewing than in actuality. The re enforcing bars and brackets (in
the rear armoured glass) in AH are too large and not sufficiently
semi transparant.

• Flight model: I am not sufficiently familiar with AH's various AC to

draw comparison. By instinct I would expect faster e loss when
manouvering (not only thru normal g losses but due to the quite
massive elevator surface area  deployed at considerable angles of
attack [short fuselage]) when manouvering. Like wise e loss when
throttled back  I would have thought been greater (plane seems to
glide for ever!)   Anecdotal evidence shows that the Lavochkin was
able to decelerate quite rapidly........Infact it is often quoted
as Kuzhedubs and Popkovs preferred method of attack to perform a
high speed high G dives/manouvers rapidly decelerating onto the
opponents hind quarters. This would suggest that AH may wish to
increase max propulsive power and nominal drag on both Lavochkins.
[/list]

"The above is not meant as a whine........ given AH's level of progressive
development I reckon that they are all things that could be corrected if
proven to be true."



[This message has been edited by Westy (edited 03-29-2001).]

[Betown]

I like it's "Anti-Whine" factor. It's a hit! I think HTC will take an intrest.
You have either started one hell of an argument or a really nice peaceful thread commending your friend on his efforts.
One of the other
"Blow Torches at the Ready"
BT

[Raubvogel]

Very good comments, I think some of them are not only Lavochkin-specific, but all valid points.

[funked]

Has anybody tested sustained turn speed and rate?  The last test I saw showed the La-5FN almost identical to VVS flight test data.

Also the climb rates are spot-on, so a thrust increase is not needed.

My Lavochkin loses plenty of speed in high G maneuvers or with the throttle closed.

Tell your friend to get some numbers, because all the ones I have seen indicate that drag and thrust are just about spot-on.

[Sorrow[S=A]]

About the engines:

The Ash 82 was by no means prone to overheating in 2 minutes- this is the first I have EVER heard that written- I would like to know where he saw this?

Flight tests actually reported no real heat increase in the La-5FN under it's boost system at low altitudes. Many pilot reports indicate they were able to run extremely long periods under boost with no problems. The 10 minutes we have now is based on the mechanical rebuild limit- after 10 minutes it was required to break the engine apart to examine and replace any failed seals or bearings.

I think what he is saying is that no-one but the most desperate pilot ever maintained an La-5FN under WEP for a long period of time. The cooling system for the oil ran under the cockpit and could raise the tempurature of the cockpit over any bearable level. The test report indicates it as high as 38`C after only 5 minutes. The La-7 had vents installed to alleviate this problem.

I agree 100% about the gunsight. It appeared to sit higher and required the pilot to maintain a very high seat position in the plane. At least the AH one doesn't shake too hard to be properly seen through while firing though!

All hydraulic flaps in AH use the servo step system based on how far the hydraulics could push them at a given speed. I think it's generic on most planes except US ones where Pyro has exacting data. A two step system would be less useful as currently you can control the flaps more exactly.

Others answered the speed/drag issues better than I. I will say however that those tactics still work in AH- they were the first lesson I learned from Leonid when I joined the 5GIAP in AH. To stop so quickly utilize the extremely large rudder to yaw and the planes all lose speed extremely quickly. It makes no sense to think the La-7 would have high nominal drag or fast E bleed without this- her drag was the lowest calculated drag on a Radial engined fighter in WWII AFAIK.

Sorrow

(BTW westy- who is the person you posted this for?)

[Tilt]

My Lavochkin loses plenty of speed in high G maneuvers or with the throttle closed.

Tell your friend to get some numbers, because all the ones I have seen indicate that drag and thrust are just about spot-on.[/B][/QUOTE]

I have a complete set of original numbers for the La7 but alas they miss roll rate and an actual defining  measure of drag v propulsion. (except what little indication could be gained from different climb rate tests and "combat turn tests" some times called a "chandelle")..and so have  to admit that it is more a "feel" from anecdotal texts and combat reports.

In such a sim enviroment as AH balance is important and so it should perform in a comparative manner to other AC as it did in history. (in other words it's performance in comparison to other AC is as important to represent as its actual numerical performance alone)

eg in a dive the AH la-7 just seems to keep accelerating as if the prop had infinite variablity and drag was not kicking in. I should compare this to a 109G4 where by although initial acceleration should be slower than the La-7, later stage of acceleration in a dive was faster/higher than the La 7. (VVS report 48576 file 273 11 Oct 44) yet the la7 in AH continues to accelerate to wing rip at 500 plus mph. This is the same La 7 that was superior in vertical manouvers (to the 109G4 when tested) up to 3500m and equal upto 7000m. Again not direct tests for drag but it does suggest that

An La7 should not be able to rely on a long dive to safety from a 109g4/6/10.

But the La7 could climb to safety up to 3500m  or given separation simple run level from at least the G4 accelerating to a higher level top speed.

To my mind AH models most of this very accurately except the dive and as the limiting factor on dive is drag then it would suggest that the La 7 (and therefore the La 5)drag coefficient in AH is too low.

Increasing it would require a balancing increase in power  to sustain its simulated performance in other plains (vertical and horizontal)

btw I have no reports of wing rip due to high speed manouvering from either La 5's or La7's.(except where glue is missing from the structure) The VVs did very extensive wing loading tests and the Czechs repeated them in 46 when they found the wood strength was reduced by half due to rot and fungal attack. After the tests the Czechs found the structure to be stronger than their 109's even tho the component wood material had been severely weakend. They continued to use them until 1950.

btw the line art for the underside of the AH La 7 is that of an La 5. The La 7 had wheel covers to fully enclose them when retracted.
 http://www.btinternet.com/~fulltilt/la7frontgear.GIF

and the under wing stars had white/red borders.

On the up side I do enjoy flying the La 7 online ................. ;o)

Tilt

[Tilt]

 

Originally posted by Sorrow[S=A]:
About the engines:


(BTW westy- who is the person you posted this for?)

It was me.

Re the two minutes. This record was from Cezch sources who used the La5FN during the 44 uprising. Inparticular reports by one Ladislav Valousek and Frantisek Fajtl DFC who left England in 44 to form a Czech contingent in the VVS.(then put into Slovakia)

He (Valousek) reports most emphatically that WEP (1850 hp @ 2500rpm) could only be maintained for up to two minutes after take off. He further goes on to say that cylinder head temperatures had to be watched very closely as " there had been cases of this engine literally loosing there heads"..after which he generally sings its praises interms of an actual combat fighter against the 109's and 190's.

Anecdotally I have many performance curves for the La 7 showing additional speed and ROC due to WEP. But all my original La5FN curves miss the WEP contingent.( the La 5F and La 5 do show a form of WEP but the engine conditions for this are not clear)

I have the engine data book ( scanned copies) of the Ash82 FNV. You are quite correct this shows  a 10 minute period at 2500 rpm (1200 mm manifold pressure) and even a 30 second period at 2600 rpm.

The La 5 oil cooler was forward of the cockpit. Hot oil heating the cock pit was a problem with the La 7 when the oil cooler was moved to the rear.

Agreed re the shaky gun sight. I have stood on a chair  at Kebly air museum and leaned into the cockpit of White 77 and it does seem precariously mounted on strips of wood.

From what I can see the simple valve used to set flaps had three positions. However It should have been possible to jiggle the valve to set intermediate ones.

I will try using the rudder to induce drag more. I must admit to having it set to a wide dead band to avoid "accidental"use.

Agreed re the nominal drag coefficiant for a radial v radial comparison (althought the 190's do surprisingly well in the speed v weight v power stakes) but that should not necessarily make it as good as most inline engines (drag).

Tilt

[Sorrow[S=A]]

Hi Tilt!

In the case of the 2 minutes- I think he was exagerating. It definitly sounds like a repitition of rumour from others than actually going past 2 minutes and seeing what occurred. In practice the heads engine would level at a very high temp (past his red demarking line) and run at this level for a long time. After 7-10 minutes pilots reported predetonation and exessive oil burning in the exhaust and throttled back.

This is true for many planes- because pilots were not allowed to push the engines the VVS tests show the G-6 and later to have only 2 minutes of sustainable boost because test pilots would back off when the coolant became overheated to prevent the possibility of engine damage. However german tests clearly show the DB series could run for up to 10 minutes before incurring serious damage to themselves.

About WEP-
The early La-5 did not have this overboost- it was not actually added until later. You are right that the conditions of what this "boost" was are completely unclear. I think the WEP curve on the La-5FN would be indicative of full throttle as pictures of the cockpit etc do not clearly show any method of engaging a "boost" system.
I think pilots were just told to never go above X position on the throttle (Was there a friction block on the throttle?) unless it was an emergency.

All of the paperwork for the La-7 performance evaluations submitted to the goverment to allow production do show these curves seperatly from normal boost. Perhaps the engineers felt no reason to identify it as an "overboost" in the fist evaluations as this would have made it look worse compared to other planes? I know there was a great deal of polotics involved in Lachovin managing to get production for his planes.

AFAIk re the oil heater both were equally as awfull. The ones under the floor created more heat but the canopy vents on the La-7 allowed the pilot more air cooling as well. The ones on the La-5 were just as bad and had no way too cool but to 1/2 open the canopy.

I found the info on Dives VERY interesting. I noticed many times how easy it is too rip wings in a dive and found it odd. Also- notice that P-47 and 109 for all intents and purposes dive the same except for a slight acceleration difference. What your saying makes me wonder if the 109's lower terminal dive velocity isn't coming into affect in AH.

As per artwork- look closely at the La-5FN.. when Nate reworked the cockpit he mirrored the artwork for the La-5, now we have symmetrical gun bulges of equal length on the nose  

BTW if you have info from the Czech planes- can you tell me any info on the Trainer based on the La-7 they used? I read it was in service until 1982 but no more information on it  

[Daff]

"He (Valousek) reports most emphatically that WEP (1850 hp @ 2500rpm) could only be maintained for up to two minutes after take off. "

Ah! "after take off".
Most WW2 planes have a lot shorter time-limit on take-off power than WEP, despite using the same powersettings, simply because after take-off you will usually start a climb at slow airspeed, providing less cooling for the engine.

Daff

[Tilt]

Well they both flew the La5FN in combat from August 44 to April 45 and later as part of the Czech airforce. It is not clear whether these planes were part of a 43 or 44 (FNV) production batch but I always assumed they would be pure FN type engines.

I cannot categorically state that the La5FN could not sustain WEP (2500 rpm) for longer than 2 mins. The only 1st hand reference I have to such WEP is in lavouseks reports. I donot have any curves showing WEP'ed performance for the La5FN.

As the throttle, boost and prop pitch were all separate controls on the La5FN then I think it was simply a red line on the RPM meter.

The politics (usually the results of the machinations of one comrade Yakovlev)were mainly over  re production recource competition by the end of 42.

The 44 prototype la7 (etalon of 1944) shows figures way beyond thiose any la7 ever produced........... and the curves do not show an additional WEP curve. It is suspected that this was tested regardless of engine life... we should never trust prototype figures. In fact in submitting these figures they also showed no WEP for the La5FN (but did for the La5-F ??)

I suspect that the small vent over the armoured screen was not added until after the war.
 http://www.tilt.clara.net/White77/cockpit.html

The La7 had small wing vent holes in the leading edge nearest the wing root which were piped to the cockpit.
 http://www.tilt.clara.net/White77/wings.html

The La 5 has small fuselage vent scoops just below and forward of the cockpit.

see item 35 at http://www.btinternet.com/~fulltilt/la5cut.GIF
 The main ventilation problem on all Lavochins was exhaust gasses leaking into the cockpit..(also resulting in condensation)usually a perpetual battle occurred with this with constant sealing and filling of gaps by ground engineers.

I cannot find a reference to a 7UTI in the 2  Czech regiments equiped with Lavochkins. (this does not mean they didnt have one) The La 7uti was not a success and infact the original design (1st built in october 44) was abondoned in   April 46 after protracted prototype failures. The final design resembling a hybrid version of the La5 UTI and the original La7uti but came to late as the La7  was removed from  production for the VVS during 46 and only a few La7UTI's were made for use.

I do have records of 2 la5 (FN) UTI's with the Czech airforce. (one marked FW-5 on its fuselage and another whose original Russian marking was "white" 2 {tho it could even have been the same air craft})

Tilt

[-towd_]

la5 cut gif

anyone notice what appears to be a bomb?


YIPPI!!

[J_A_B]

According to the info, it's a whopping 50kg bomb.

J_A_B

[SKurj]

a 50kg will kill an osty, or at least a pair will +)


SKurj

[Tilt]

 

Originally posted by J_A_B:
According to the info, it's a whopping 50kg bomb.

J_A_B

Both La 5 (F,FN) and La7 were /could be equipped  with the D3-40 bomb rack (one on each wing)

These could each carry upto 100 kg bombs being the

50 /100 kg FAB GP bombs (refered to elswhere as fragmentation bombs)

or the

50 /100 kg ZAB incendary bombs.

the 50 kg bomb was the most common.

Electric bomb release was by a button on the joystick (top) (la7)

Manual bomb release was by a single lever to the left of the pilots seat. Its design suggests that its cable released both bombs at the same time.

The wing was also suited to  take 4 (per wing)of the  RS-82 rockets and launchers. (All yak1/7/9's were also capable of taking 3 per wing) The VVs used rocket attacks less in the later war years on their  fighter bombers. They were initially seen as air to air devices (RS-82) against LW bombers and latterly became more the preserve of IL2 M3's in their ground attack role (4 per wing but maybe another rocket type).

However rocket equipped la5's were probably no more uncommon than the 3 cannon la7.

A nice game balance may be achieved by allowing the rockets on the la5FN but not the La 7. I do not know if AH caters for different rocket types or just uses one generic type.

All la5 / la7 pilots were trained in bomb release and targeting.

Tilt