ANY sort of weakness for La7!

[Tilt]

Originally posted by Robert

Manifold pressure resumes. La7 has the same Manifold pressure
drop at the same alts. Then regains the same pressure at 17k
just like a 2 stage charger. If it doesnt have the 2 stage charger
shouldnt it's Manifold pressure continue to drop as you gain
more alt.


RWY

.

Your observations are correct and the AH indicated manifold pressure curve of the La7 and La5 are incorrect IMO at mid altitudes.

Height______Boost______Speed (IAS)
M_________mm.pt.ct_______ Km/h
0000________1000________ 270
1000________1000_________270
2000________1000_________270
3000_________900_________265
4000_________825/1000____260  (2nd stage/speed of boost)
5000________1000_________255
6000_________900_________250
7000_________765_________240
8000_________660_________240
9000_________600_________235
10000________550_________230


These figures are off an August 44 La7 climb rate test and show only the non WEP (2400rpm) boost v altitude.

WEP (2500 rpm) generates 1180mm (46.46") of boost upto approx 2000m+ (6600ft) where it fades to 1000mm (39.37") by about 2600m (8500ft)

You will also note that this is at max climb so there is little RAM air effect at the intake.

In AH units this would read

Height______Boost______Speed (IAS)
Ft__________inches________m/h
0000________39.37_________168
3278________39.37_________168
6557________39.37_________168
9836________35.43_________165
13114_______32.48/39.37____161  (2nd stage/speed of boost)
16393_______39.37_________158
19672_______35.43_________155
22950_______30.11_________149
26230_______25.98_________149
29508_______23.62_________146
32786_______21.65_________143


Manifold pressures indicated and given in the E6b are therefore slightly erronious IMO (for both La5Fn and La7).

WEP boost was 46.5" not 48". Mil power was 39.4" not 41".

The 2nd stage of boost is permitted at just over 13K and not at 16>17K as the Lavochkin cockpit manifold gauges indicates.

In fact if you refer to AH's own climb rate curve for the La5FN & La7 you will see that the 2nd SC speed step is about 13K and maintained as per the above test until 16.5>17K.



The various speeds and climb rates modelled seem to be pretty much spot on for a fully tested production model however. So we may be being fussy and the only performance curve affected due to any error may be limited to fuel consumption rates at the differring altitudes.

[Robert]

So it does have 2 stage supercharger ? If im reading everything
right in AH it does.

RWY

[Tilt]

Originally posted by Robert
So it does have 2 stage supercharger ? If im reading everything
right in AH it does.

RWY

Yes the 2nd stage of boost should be engaged at 4000m alt and max throttle set to limit boost to 1000mm max which is  achievable upto approx 17K where after boost fades with altitude.

[Grits]

Originally posted by bj229r
Doesnt need to be perked, just give it 1 or 2 of the weaknesses that it likely had:mad:

Most La7's have a serious weakness, which is the guy flying it.

[AKDogg]

LA7's are quite easy to kill.  Just got to catch them.  I kill them all the time in my F4u-1.

[Karnak]

Originally posted by MwDogg
LA7's are quite easy to kill.  Just got to catch them.  I kill them all the time in my F4u-1.

You'd find it much harder in an Fw190 of some sort.

The F4U is an exceptially good and versatile fighter.

[bj229r]

Originally posted by Widewing
I don't get it. Why didn't you simply climb away, reverse and kill the damn thing? A P-47N simply owns an La-7 at 20k. Better acceleration, better climb, faster and if you're not hauling around too much fuel (never need more than 50%), you can defeat it in a turn fight. Any putz willing to follow you 2 sectors likely couldn't fight his way out of a nursing home restroom with submachine gun anyway. Don't worry about the other guy, make him worry about you.

My regards,

Widewing

Was a YakU about with the La at first, which then started climbing to nail if I tried that very thing....what truely hacked me off was all I had to do was TURN WEP off and La started CLOSING...after a while, when I was sure he was out of E from his earlier dive to 20k..started checking that out, and concluded the only speed difference between the 2 of us at that alt was my diminishing wep...unless my chitty dial-up connect lets it catch up in bits and spurts

[Tilt]

Originally posted by Tilt
In AH units this should read

Height______Boost______Speed (IAS)
Ft__________inches________m/h
0000________39.37_________168
3278________39.37_________168
6557________39.37_________168
9836________35.43_________165
13114_______32.48/39.37____161  (2nd stage/speed of boost)
16393_______39.37_________158
19672_______35.43_________155
22950_______30.11_________149
26230_______25.98_________149
29508_______23.62_________146
32786_______21.65_________143



But AH actually shows...


Height______Boost______Speed (IAS)
Ft__________inches________m/h
0000________39.37_________168
3278________39.37_________168
6557________39.37_________168
9836________36.50_________165
13114_______32.48_________168  
15000_______30.00_________168 (2nd stage/speed of boost only reaching full boost @)
16393_______39.37_________168
19672_______38.50_________168
22950_______34.00_________168
26230_______30.00_________168
29508_______26.00_________168
32786_______22.50_________168

So what we see is that AH inititiates 2nd SC at 15k instead of 13K+. Which gives lower MP between 13k+ and 16.4k than RL.

Above 19K AH shows higher MP than was evident in RL


Given the above if the drag v thrust balance was altered to maintain speeds and climbs (both values increased) but thrust curves modeled to show the above MP curves.

Would not the Lavochkins suffer even poorer acceleration (e retention)above 16.5K?

Further would not then the Lavochkins suffer poorer aceleration in dive at speeds above  equivilent horizontal speed?

Its a matter of record that beyond initial acceleration in dive ...even a BF109G4 could out dive an La7!