How good is the LA-7's Engine?

[crowbaby]

>>Try this for starters. - Blogs <<

Unfortunately, this is just the SEFC for the F4u. I can't test the F6f from this. They may have the same engine, but they're obviously not comparable:

Combat Weight-
F6f5 - 12,740
F4u-1 - 12,405

Fuel
F6f5 - 250 Gallons
F4u-1 - 234 Gallons

Range
F6f5 - 1,130 miles
F4u-1 - 1,515 miles

[funkedup]

Joeblogs sez:  

Specific fuel consumption is reported for the most fuel efficient settings of the engine, not for the rated power of the engine. That means auto-lean fuel mixture at something well below an engine's rated power, typically 65 percent of normal or 50 percent of military power.

If you can get an SFC of 0.54 on auto rich, you have an amazing engine. SFC on auto-rich for high output US radials is on the order of 0.8 to 0.9 for normal and military (non wep) power settings. Given that the ASH-82FN is no more efficient (in fact it's less efficient) than a comparable American engine in auto lean, it is extremely unlikely to be more efficient in auto-rich.

My estimate of the implied SFC for the ASH-82FN in AH is on the order of the low 0.30s, which is simply implausible.

OK I understand what you are saying.

[Karnak]

Thanks for taking an honest look at this stuff crowbaby.




I also noted that the Spitfire on full power guzzles fuel as well.  There is no way that a fully fulled Mosquito should run out of fuel before a fully fueled Spitfire if similar power settings are used.  The furball friendly endurance chart that snefen created should still favor the Mosquito over the Spitfire by about twice because the single Merlin on the Spitfire consumes fuel as fast as a single Merlin on the Mosquito, and the Mosquito carries five times the fuel load.

[joeblogs]

Download the standard aircraft characteristics for the hellcat from:

http://www.history.navy.mil/branches/hist-ac/fighter.htm

It has all the data you need to work out the endurance of the f6f-5.  I use that data in one of my orginal posts.

-Blogs

Originally posted by crowbaby
>>Try this for starters. - Blogs <<

Unfortunately, this is just the SEFC for the F4u. I can't test the F6f from this. They may have the same engine, but they're obviously not comparable:

Combat Weight-
F6f5 - 12,740
F4u-1 - 12,405

Fuel
F6f5 - 250 Gallons
F4u-1 - 234 Gallons

Range
F6f5 - 1,130 miles
F4u-1 - 1,515 miles

[F4UDOA]

Just got home from a long day to find this.

1. JoeBlogs- Don't apologize for being too compicated. If I understand it's not complicated. What your saying makes pefect sence.

2. Crowbaby- You keep comparing apples and oranges and your making this much more comlicated than it is really.

A. Don't use any power condition other than full Mil power for testing. Nobody flies anything other than full mil power in AH anyway and it skews the results when you change to normal or max continious. For the purpose of testing use the La-7 vrs F6F or F4U-1D(The -1D had 237gallons of fuel internal).

B. You have referred several times to the extra weight of the F4U and F6F compared to the La-7. Also you have mentioned range. None of this is relavent when you are testing endurance at a given power setting.

Pretend the R-2800 and ASH-82FN are sitting in jack stands in a garage IE there is no airplane. I set them both to run at mil power. How long does it take the ASH-82FN to burn 122 gallons of fuel? How long does the R-2800 take to burn 237gallons and then 250Gallons. That's all I need to know to prove my point.

La-7 122 US gallons internal
ASH-82FN
Rating (military, low) 1650 HP/2400 RPM/5400 ft


F4U-1D 237 US Gallons internal
R-2800-8W
Rating Mil Low   2000HP/2700RPM/2500FT

F6F-5 250 US Gallons Internal
R-2800-10W
Rating Mil Low 2000HP/2700RPM/2500FT

Meaning that

1. Fact- The ASH-82FN put out 82.5 percent of the power of the F4U/F6F at equivilent power settings.

2. Fact- The F4U had 49% more internal fuel.

3. Fact- The F6F had 52% more internal fuel.

4. Fact- In AH the La-7 has equal flight time duration at mil power as the F4U-1D and 2 minutes less than the F6F-5
My point of contention.

Question How does the ASH-82FN produce 82.5% of the HP of the R-2800 and only burn 50% of the fuel during the same time period   . I do not believe this is possible.

[F4UDOA]

Proof    

This is part of a VVS doc posted in the last thread. Note the highlighted area that specifically list a mil power duration of 33minutes at 460Litres or 122gallons.

        Fund of NII VVS, inv. 485716, file 273

         Approved. Chief Engineer of VVS A.Repin, 11 Oct 1944

                        THE STATEMENT
on results of verification trials of a serial La-7 with ASh-82FN engine and
                 VISh-105V-4 propeller, D=3.1m
        /ac.No 45210203, prod. in July 1944 by factory No 21/


                   Air combat with Me-109G-4

In horizontal manoeuvring up to 5000m the La-7 gets on the tail of
the Me-109 for an aimed shot after 3-4 turns. Above 5000 m the advantage of
La-7 in horizontal manoeuvre decreases. At an altitude of 7000m horizontal
manoeuverability of both planes is equal.

In vertical manoeuvring the La-7 has an obvious advantage over the Me-109
up to 3500m and can keep an altitude dominance of 150m during combat. When
it reaches an altitude of 3500m the La-7 slightly loses its superiority over
the Me-109 in vertical manoeuverability, but even at 7000m the La-7 can
maintain a dominance of about 40-50m. At 6500-7000m the vertical
manoeuverability of both planes is equal.

The La-7 accelerates into the dive faster than the Me-109 and therefore can
reduce the distance to an escaping target. However, in continuous dive the
Me-109 increases its speed faster after initial acceleration and departs from
the La-7.

------------------------------------------------------------------------
========================page02.gif======================================

          Approved. 1st Deputy Chief of GK NII VVS Losyukov. 6 Jan 1945.

                          REPORT No 2
on results of flight trials for fuel consumption and range measurements
of La-7 No38103254 with ASh-82FN engine and VISh-105V-4 propeller.

                     The object of research

La-7 No 38103254 produced by plant No 381... Total weight 3265 kg, fuel tanks
capacity - 460 litres. The landing-gear and the tail wheel were up,
the canopy was closed, the cap of oil-cooler and the skirt of engine cowl
were set "along the flood" (feathered).

                    The results of the tests.

The measurements of fuel consumption with working engine had been carried
out on the ground and during a climb at max climb rate. As a result it has
been established that fuel consumption of a working engine is 2.35 l/min
on the ground (during warm-up and engine test, taxiing to and from the
starting position).

Fuel consumption at climb to H at maximum climb rate mode, in litres
                          n=2400RPM

H,m       1000    2000    3000    4000    5000    6000    7000
Q,litres    15      25      35      45      55      65      80
IAS, km/h  270     270     270     265     260     255     250


Chart of range and level flight duration of a/c La-7 No38103254 at different
flight modes at V/n=const (constant speed and RPM), G tot=3265kg (total
weight) and V fuel=460 l (fuel volume)

n,   Supercharg. Speed, km/h     q,      Qf,       Till the dry tank:
RPM  pressure,    IAS    TAS  lit./km  lit./h    Range of    Level flight
     mm of merc.                               level flight,   duration,
     pile                                          km           h-min

H=1000m (1st speed of supercharger), fuel supply for level flight - 365 l

2400   1020       575    608   1.020     620       355          0-35
2200    875       530    560   0.800     448       455          0-49
2000    745       480    508   0.655     333       555          1-06
1800    665       430    455   0.585     266       625          1-22
1600    610       385    407   0.560     228       650          1-36
1500    580       360    380   0.550     209       665          1-45

H=3000m (1st speed of supercharger), fuel supply for level flight - 345 l

2400    990       554    644   0.975     628       355          0-33
2200    830       510    588   0.745     438       460          0-47
2000    705       460    532   0.620     330       555          1-03
1800    615       415    480   0.575     276       600          1-15
1600    560       370    428   0.555     238       620          1-27
1500    545       345    400   0.550     220       625          1-34

H=5000m (2nd speed of supercharger), fuel supply for level flight - 325 l

2400   1020       513    658   0.910     600       355          0-32
2200    840       470    604   0.700     423       465          0-46
2000    720       430    554   0.600     333       540          0-58
1800    630       385    496   0.560     278       580          1-10
1600    590       340    440   0.550     242       590          1-20

H=7000m (2nd speed of supercharger), fuel supply for level flight - 300 l

2400    870       454    647   0.735     476       405          0-38
2200    685       415    593   0.570     338       525          0-53
2000    590       380    544   0.500     272       600          1-06
1800    515       340    490   0.460     225       650          1-20
1600    465       300    433   0.450     195       665          1-32

Notes:

1. For range and flight duration calculations the following fuel consumptions
are taken into account:

========================page03.gif======================================

a) for engine work on the ground (warming-up and engine test, taxiing to and
from the start) 35 l per 15 min;

b) for climb to: 1000m - 15 l; 3000 m - 55 l; 7000 m - 80 l;
c) for circle flight before landing - 45 l.

2. To obtain the values of technical range and flight duration add the
following range and time figures to the table values respectively:
1000m -  5km, 1 min
3000m - 15km, 3 min
5000m - 25km, 5 min
7000m - 40km, 8 min


The table of range and flight duration for La-7 No 38103254 with
G full=3265kg, full tank fuel supply - 460 l.

Mode   Mode values                                      Level flight
                                                      up to dry tanks:
                                                     Range, km     duration,
                                                                   h-min
                                                                   
Max.   H=1000m(1st sup.sp.),n=2400, Ps=1020mm Me.pl.    355        0-35
speed    3000  1              2400      990             355        0-33
         5000  2              2400     1020             355        0-32
         7000  2              2400      870             405        0-38

Fast   H=1000m(1st sup.sp.),n=2160, IAS=518 km/h        485        0-53
range    3000  1              2160      498             490        0-51
(0.9     5000  2              2160      462             485        0-49
Vmax)    7000  2              2160      408             545        0-56

Near   H=5000m(2nd sup.sp.),n=1810, IAS=388 km/h        580        1-10
fast range                          TAS=500 km/h

Optim. H=1000m(1st sup.sp.),n=1500, IAS=360 km/h        665        1-45
mode     3000  1              1500      345             625        1-34
         5000  2              1600      340             590        1-20
         7000  2              1600      300             665        1-32


------------------------------------------------------------------------
========================page04.gif======================================

                      Approved. Chief engineer of VVS A.Repin, 21 Jun 45

                       The statement No 112
on results of verification trials of La-7 serial plane with ASh-82FN engine
and VISh-105V-4 propeller D=3.1m, equipped with hydraulically controlled
              dust filter and new ventilation of cockpit
        / a/c No 45213276, plant No 21, prod. of April 1945 /


        Table of max. horizontal speeds

H standard,             TAS, km/h
  m               nominmal, n=2400 RPM     WEP, n=2500 RPM

    0                   580                     616
 1000                   604                     639
 2000                   626                     661
 2200 1)                 -                      666
 3000                   649                     657
 3250 2)                654                     654
 4000                   645                      -
 5000                   651                      -
 6000                   672                      -
 6250 3)                677                      -
 7000                   666                      -
 8000                   651                      -

1) - 1st altitude boundary with WEP
2) - 1st altitude boundary without WEP
3) - 2nd altitude boundary without WEP

              Table of max. climb rates

H st., m   Vy (vert. speed), m/s    Time, min           IAS, km/h
              nominal   WEP       nominal   WEP

    0          20      24.2        0        0            264
 1000          20      24.2        0.85     0.65         259
 1600 1)        -      24.2         -       1             -
 2000          20        -         1.7      1.3          253
 2650 2)       20        -          -        -            -
 3000          18.6      -         2.6      2.2          246
 4000          15        -         3.55     3.2          239
 5000          15        -         4.65     4.3          232
 5100 3)       15        -         4.75     4.4           -
 6000          12.7      -         5.9      5.45         224
 7000          10.2      -         7.4       -           214
 8000           7.6      -         9.3       -           204
 9000           5        -        12.0       -           189
10000           2.4      -        16.6       -           166
10750 4)        0.5      -        26.0       -            -

[F4UDOA]

Funked,

You said

We know (from Snefens' chart) that endurance at this power setting in AH is 28 minutes. Fuel multiplier is 2.0, so in "real life" terms it would be 56 minutes or 0.93 hours.

Fuel capacity (from the AH aircraft info page) is 122 gallons. At 6 lb / gallon that's 732 lb of fuel.

So the specific fuel consumption is 732 lb / 1470 hp / .93 hr = 0.54 lb/hp-hr.

Compare this to the real world figure posted above, of 0.46 lb/hp-hr.

Looks like the La-5FN and La-7 use about 16 percent more fuel than they should.

That SFC of .46 is measured at cruise power for the La-7. The equivelent setting for the F4U/F6F would be .442 at 5K.

That gives the F4U-1D a duration of 338 minutes (5.63 hours) and the F6F-5 a duration of 357 minutes (5.95 Hours).

Compare that with the La-7's duration at equal SFC (assuming both engines are equally efficient) of .93hours.

That gives the La-7 a almost a 500% increase in duration compared two it's two rivals. Not 16%.

So bang the Drum loudly!!

[crowbaby]

Ah, so we're still unhappy with the La7.
What you have highlighted is the summary of the report i tested AH against. You forgot to highlight this bit:
1. For range and flight duration calculations the following fuel consumptions
are taken into account:

========================page03.gif======================

a) for engine work on the ground (warming-up and engine test, taxiing to and
from the start) 35 l per 15 min;

b) for climb to: 1000m - 15 l; 3000 m - 55 l; 7000 m - 80 l;
c) for circle flight before landing - 45 l.

2. To obtain the values of technical range and flight duration add the
following range and time figures to the table values respectively:
1000m -  5km, 1 min
3000m - 15km, 3 min
5000m - 25km, 5 min
7000m - 40km, 8 min
this was the reason i climbed to alt and tested against their fuel consumption figures. It made for a much simpler test.

I think it's the whole SFC/horsepower/comparing engines debate that's apples and oranges. You're looking at engines' consumption at a maximum continuous allowed by AH, for which we have no historical data.  Unfortunately AH doesn't simulate jackstands in a garage. If this is your thing, then fine, but it leaves me cold. I don't know much about how the engines differ. Intuitively, it seems o.k. to me that (at its must uneconomical settings) one of the biggest fattest fighters of WW2 uses fuel twice as fast as one half its weight. Or:
Question How does the ASH-82FN produce 82.5% of the HP of the R-2800 and only burn 50% of the fuel during the same time period  . I do not believe this is possible.
It doesn't seem completely unreasonable to me that one engine should consume nearly twice as much fuel as a completely different one to produce 21% more power.

All i'm doing is testing the planes against the best information we have on how they were actually flown. As i've said, if they match that, then i'm happy, it's a flight sim after all. So maybe we're after different things, it's fine to disagree. I'm off to bed. I'd still be grateful if anyone could find an SEC or FOIC for the F6f-5. Failing that i'll test the F4u tomorrow.

[HeLLcAt]

For the people who do not know what it looks like lol...

[F4UDOA]

Crowbaby,

Test the F4U. There is more inforamtion available there anyway.

But you are way overcomplicating things.

The whole point is this.

The F4U and F6F were both long range fighters by comparison to the La-7 which was a point interceptor.

Based on that historic premise I asked the question why then is the AH flight duration (not range since the purpose in AH is not to fly far) the same between long and short range fighters since this surely puts the long range fighter at a large disadvantage.

Testing, all testing should be at mil power since that it what is used primarily in AH.

SFC- the available SFC data puts both engines at approximately the same level of efficiencywith a slight advantafe to the R-2800. Remember the R-2800 was a high tech engine and was the successor to the R-2600 and prior P&W power plants. The ASH-82FN was in fact a copy of the R-2600.

If the SFC's are equal then the duration of the A/C with the larger fuel load will ALWAYS have a longer duration.

Things like weight and range are characteristics of aircraft not engines and have nothing to do with duration.

Point being if I'm in my F4U-1D I should be carrying 25% fuel to engage a La-7 with 75% fuel and that would give me historically accurate equal duration for both A/C. Otherwise it's just arcade mode.

Of course this affects the Mossie, P-47, P-38, P-51, F6F and F4U the most. If you fly a 109, LA-7, Spit or Yak this probably is not great news.

[Pongo]

too bad you had to slip to..
"my plane needs more range or its just arcade mode"

Goes along with
"My plane needs to be the most robust or its just arcade mode"


You make a huge point of these being long range fighters..But they accomplished alot of that range with a massive external fuel capability
Both the corsair and the hellcat can engage an la7 with 25% fuel if they take any external fuel at all..

That simple point makes all this whineing about the La7 kind of silly.

[F4UDOA]

Pongo,

Please don't miss the point.

It's not my plane or his plane or anyone elses. It's either right or it's wrong. It's not subjective.

I'm not whining about the La-7. I really don't have trouble with them in the MA. In fact I think they are overrated. However I think somethings take a back seat to game play and arena parity because having a fuel multiplier that would limit the la-7 15minutes with a full tank would give a P-51 a full hour. So the answer is to bend reality in favor of better game play.

Well thats great if you are a big fan of tiny airplanes but it's one step closer to arcade more as far as I'm concerned.

BTW I have no idea if it is intentional, an oversight or otherwise becuase HTC hasn't said a word in about three threads full of this stuff.

But if you think I wrong feel free to correct me

[Pongo]

Originally posted by joeblogs
Yes upping w 25% internal fuel and a drop tank is the right reponse.  But that is not really sufficient to cap a CV when you don't know when you can land next.  

Besides you have to lose that drop tank as soon as you engage, or you can't turn worth %$$$(**& and then the heavy iron fuel penalty dictates you have about one dogfight before you are out of gas.  This does not strike me as sensible game play.  

-blogs

Your worried about an La7 attaking your CV?

Good response F4DOA

I still think that damage to a base should limit your fuel in gallons..not %..then we will see how much of a range advantage those big planes get.

[crowbaby]

O.k. I can see how the figures look funny:

F4u-1                        
2000hp             -   from SEFC
for
43mins              -   from Snefens
with
361 gals            -   from HTC
=
238hp*min/gal

La7
1650hp           -     quoted by joeblogs from Aircraft Engines of the
for                        World, published in 1949.
28mins            -     from Snefens
with
1650                -    from HTC
=
378hp*min/gal

which would mean that the F4u engine is working only at 63% of the efficiency of the La7 engine. However:
-We don't know that any of these HP figures are accurate.
-We have no historical data to compare to Snefens tests because its an arcade-y way to fly the planes.
-We really can't assume any equivalence of engine performance. If engine performance was as simple as fuel in equals HP out across a range of power outputs. If engines were that staightforward,  then people wouldn't write head-breaking reports like these:
1943 study on fuel economy and' crank angle'
similar report on 'inlet valve design' and power output efficiency

In addition, i understand that the ASH-82 engine was fuel injected? and that the R-2800 was not? I can't find corroboration on this, but it would also explain a difference in efficiency at high output settings. 1939 NACA report on injection v. carburetor here

Thus, i still maintain the only sensible thing to do if you have concerns is to test the planes against reliable performance figures. I now plan to do this for the F4u-1. Offline, i'll test with no wind, fuelburnmult at 1, against a range of settings from this chart. Again, i'm only interested in endurance, not climbrate or anything else, just level flight at alt and settings as listed.

[Karnak]

Wouldn't it be easy enough to test the endurance of the F4U, F6F, P-51 and any other long ranged aircraft against their historical endurance and verify that they consume too much fuel?

I suspect that aircraft like the La-7, Spitfire and 109 are fine and it is simply that the long range aircraft are consuming fuel too rapidly.