Why the La7 is so Uber(important)

[214thCavalier]

Yes Whels I appreciate that but F4UDOA's  point was why does the LA7 and F6F have nearly the same flight time at Mil power in AH when the F6F carries twice as much fuel ?
There is no question that the F6F will be airborne a lot longer if you use Cruise power settings and altitudes.

Oio if you look for max flight times of which i have seen nothing mentioned for either plane, all i see is max range and combat radius figures, neither of these represent flight time at Mil power settings.

F4UDOA's concern was that the LA7 was using some magical economy engine, throwing all them figures around shows thats not the case and its fuel consumption generally falls into line with the F6F.

So whats the fuel capacity in US or Imperial gallons ? that could make a large difference IF its incorrect.

IF the LA7 is modelled with Imperial gallons and it should be US gallons then drop the fuel capacity by 0.83 and the flight time.

However i suspect its more likely the capacity was in Imperial gallons.

Understand i am not pushing to alter the LA7's duration just trying to answer F4UDOA's question, but if it is incorrect then by all means lets get it right.

[Pongo]

because its beautifle.

[Booky]

Ok. I must come in and throw my fit.  I had to run home away from my first contacts of the flight today two separate times. Now I was in my trusty F4U-C loaded with 100% fuel and 2 1k bombs. Both flights I flew about 15 min to the target which was about 1.5 sectors away. I dropped my eggs and looked for a fight. Now i'll add that I was climbing untill I got to about 17k-20k then I level off. Ok at about the 20 min mark I find a enemy dot. I go to engage and since he/her is low I play it safe and avoid the mindless HO's for 2 passes from this spit. I then look down for some odd reason and say OH Chit, I am like vapors. This was no more than 25 min of flight.

So I have two questions to ask.

1) Since MA is a 2.0 fuel consumption, does this mean that at full power (no WEP) the F4U-C could only fly for 50 min?

2) J.A.B. keeps ramling on about conserving fuel by flying at cruise alt and settings. Where do I find these? I have tried lowerin manifold pressure, tried lower RPM, tried lower both, tried flying high, tried lots of stuff and the only thing I can get to change the rate my fuel disappeares is to turn off the engine and glide for awhile.

Does anyone get a niticable difference in fuel consuption by flying like a slow target? I mean I don't see any difference, and that if there is one it doesn't seem large enough to justify the risk of flying slow in a Hog.

Not to mention that it takes 10 min or so just to get to 20k in Hog when loaded with bombs, so I ask again, What is the cruise alt and speed, manafold pressure/rpm supposed to be so I can try it out.

Help me, I hate running out of fuel just as I find the silly dweeby Bish/Knight at 20k.  I suppose I could just fly at 5k for them:rolleyes:

Booky

[J_A_B]

"Since MA is a 2.0 fuel consumption, does this mean that at full power (no WEP) the F4U-C could only fly for 50 min? "

Yes, that is correct.   The R-2800 consumed a HUGE amount of fuel at high power settings, hundreds of gallons per hour.  You can TRIPLE your range if you use cruise settings in the F4U, which leads us to:


"J.A.B. keeps ramling on about conserving fuel by flying at cruise alt and settings. Where do I find these? "

For the F4U-1C and -1D, a good cruise setting would be 34'' MAP at 2200 RPM (it is debatable as to whether the RPM will affect fuel use in AH but MAP definately does).   Again, this will greatly multiply your range.


Remember that different planes will benefit different amounts from using lower power settings.  Planes like the F6F and F4U, which consume massive quantities of fuel at MIL power, will benefit most from using lower cruise settings.  Other planes which don't suck up as much gas, like the Spitfires or P-40's or such, won't benefit as much although it'll still help.



Still hoping somebody can come up with definative evidence to either confirm or deny the LA7's fuel use/fuel load.



J_A_B

[HoHun]

Hi Jab,

>Still hoping somebody can come up with definative evidence to either confirm or deny the LA7's fuel use/fuel load.

From a German evaluation report of the La-5FN with Ash-82FNV engine:

Fuel (460 L): 345 kg

"The low endurance of about 40 min at rated power, which decreases further when high blower is used, deserves mention."

This is equivalent to about 137 USGPH . Rated power was 1000 mm Hg, 2400 rpm.

(The La-5FN's and La-7's Ash-82 engine featured a fuel injection, which generally tended to give slightly better fuel economy than with carburetted engines.)

Regards,

Henning (HoHun)

[J_A_B]

Hmm Henning...

The rated power you listed is basically the same as AH MIL power, 41'' hg.  Interesting!

460 litres = 122 US gallons.

40 minutes = 2/3 of an hour.

122 = 2/3 of 180, so I would think it was using 180 US GPH.

How did you get 137 US gal/hour?  What am I missing?


J_A_B

[HoHun]

Hi Jab,

>How did you get 137 US gal/hour?  What am I missing?

You're right, it should be 182 USGPH. I must have mis-typed some numbers on the pocket calculator.

>The rated power you listed is basically the same as AH MIL power, 41'' hg.  Interesting!

Hm, 1000 mm seems to be jut 39.4 in. Emergency power was given as 1180 mm or 46.4 in. But remember that this was for a La-5FN, so the engine settings might not be equivalent to those used for the La-7.

Regards,

Henning (HoHun)

[airspro]

Does anyone get a niticable difference in fuel consuption by flying like a slow target?

Yes , throttle back to a slower in flight speed and you will go farther on the same amount of fuel . I don't think the prop setting makes much differance in AH unless the engine is turned off .

Many times in P51's I throttle back at alt to move between sectors , it does work .

[214thCavalier]

Ok Fuel conservation tip,

Find the recommended cruise setting for your ride and use it, it definitely matches AH.
Lowering rpm definitely helps fuel as does playing with map.

Good to see the Gph seems to be working out at 180 US g/p/h whichever way we come at it from.

So burning 180 US gph with a 122 US gallon tank giving 40 minutes flight time, the MA's 2.0 fuel modifier should mean approx 20 mins flying only.

The current settings allow for 56 minutes at a 1 fuel modifier when it appears it should be 40.

That LA7 sure was a short range beast.

[Booky]

Thanks guys, when I get home in the morning I'll try it out. Going to run my Hog at the suggested 34" and 2200RPM, then at 34" and max rpm to see if the difference in consumption from RPM is worth the speed/endurance/times messin with it.

Does anyone else have a different manafold pressure I should try? I am kinda etchy about this since I feel my speed is going to be way hampered at these lower settings  And my Hog is already slow enough considering what im up against.

[214thCavalier]

Booky you get speed or range, unfortunately not both.
As an example the F6F cruise speed is about 167 i believe, painfully slow but it makes the fuel last a lot longer.
F4U's cruise speed will not be much different.

You save more fuel by climbing on wep to cruise alt then reducing rpm and map than you do climbing on Mil or a reduced throttle.
Reason as far as i can see is going wep you get up quicker then spend longer in the cruise phase actually saving fuel.
May sound daft but a wep climbout really is more efficient.

[stantond]

I belive this discussion will never be resolved.  My reasoning is because the AH planes are *not* historically correct.  Not that I intend to convince anyone of this.  Afterall, if the sky looks green to you, then its green.  How's that logic for ya?

The inaccuracy bothered me for a while, but I got better.  Oh sure I can look up data at several sources, but what's the point?  The planes are modeled as they are modeled.  Perhaps that's to give an advantage to those who fly them or take the time to record their performance for comparison.  Myself, I prefer the latter category.

(as an aside, the F4U-4 was a waste of someones time to model, I am fond of the plane but will never fly the current model in AH)

[F4UDOA]

Heya Gents,

That 180 GPH figure sounds exactly as I suspected!! This would reduce endurance in the LA7 dramtically in the MA.

The most important part of this equation is it causes A/C like the P-47, Mossie, F6F and F4U to fly with way to much fuel to compete with smaller A/C.

For instance

1 gallon of fuel weights approximately 6lbs.

F6F-5
250 Gallons fuel
1,500LBS
30 minutes endurance in the MA currently mil power
Wing loading= 37.37
Power loading Mil power= 6.24


LA-7
122 gallons fuel
732LBS
28 minutes indurance in the MA currently mil power
Wing loading =38.87
Power loading mil power Assuming 1500HP for mil power=  4.87

If the LA-7's fuel consumption was corrected to 180GPH then it's endurance would be 20 minutes in the MA at 100% fuel!!!!
(Sorry for repeating you Cav)

20 minutes is .66 of the F6F flight time and fuel.
.66 of the F6F's fuel is 990LBS

Changing performance to
Wingloading= 35.82
Power loading mil power= 5.98

This is a more competitive matchup for the Hellcat wouldn't you say??

[Tilt]

Originally posted by 214thCavalier
The earlier figures that were giving ridiculously low consumption figures were from Tilt's page (AH player) and he has a lot of info on the LA7 at,

But damn him he does not give the fuel capacity everything else but that !  

Sorry only just picked this thread up..... fuel consumption at various alts and engine conditions at


http://www.btinternet.com/~fulltilt/Engine.html

This is from the actual La7 pilots manual........

I am at work and will dig up some stuff on range trails I have this evening .... you must bear in mind that range time/distance was normally recorded as a factor of cruising speed...........


I seem to remember  two figures of 35 and 45 minutes depending upon boost.but will confirm


as a generalisation I would agree that the range of an La 7 would be significantly less than most bloooo planes.  Infact most VVS fighter fields moved with the fronts and AC rarely took off with any thing less than 100% fuel............ even IL2's based them selves further behind the lines than Yaks and La's......... Interestingly the the Yak 9D & T had quite significant ranges in comparison to the Yak 3, 9U and La's

[Tilt]

Following is a translation of test data on La7 range and fuel consumption..............if you wish I can put up the original Russian as well. Sorry if some of the formatting is lost

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Edited out due to poor format and linked to this file instead

Some La7 test data


Link is fixed