Lavochkin fuel tanks

[Tilt]

In AH there is one fuel tank modelled for the Lavochkins

infact there were 3 (I am assuming a late 1943 /1944 la5FN)

This consisted of two wing tanks and a main fuselage tank (forward of the wheel well).

The two wing tanks each approx 146 litres drained to the main tank via non return valves.

Each tank had its own fuel guage.

Total fuel capacity was about 466 litres and tanks were filled via smaller tanks (pots really) which were located above the wing tanks.

I do not think that it was possible to "switch" between tanks. hence the shift F function to do so would not be appropriate in AH.


All tanks were aluminium with several layers of tar soaked cloth around them such that they were self sealing. Further exhaust gases were flushed through the tanks to deny them of any oxygen.

In practice this meant that

Several holes were required  or severe explosive round damage before any leaks ensued.

If a wing tank was seriously holed then it did not drain fuel from the other two.

If the main tank was holed then it drained all fuel.

Also the wings were lightened as fuel was used

Fuel fires were rare

[Shane]

maybe for ease of modeling, based on the factors you described, they've all been put into "one basket" - the main fuel tank.

my only question would be, is the current fuel capacity the same as the breakout your provided?

I can't honestly remember the last time i had a "fire" on an la7.

[Tilt]

Originally posted by Shane
I can't honestly remember the last time i had a "fire" on an la7.

Nor me

I have had a fuel leak drain the whole tank tho and if we are modeling holes in wings now...............

[hawker238]

What are the adverse effects of pumping exhaust gas into your tanks?

[Tilt]

Originally posted by hawker238
What are the adverse effects of pumping exhaust gas into your tanks?

You have to cool it first and so have to carry the extra weight of a heat exchanger............. what ever that is.

[Cobra412]

On newer aircraft it's called a Fuel Oil Heat Exchanger.  As the temperature of the fuel heats (detected by a sensor in the main fuel lines)up the fuel is cycled through the FOHE then out to the wings through recirculation valves.  By putting it back in the wings it's able to cool the fuel quicker. The fuel is then recycled back through for use.

As far as pressurizing the tanks I'd have to look and see but I believe ours uses conditioned bleed air from the enviromental cooling system through the secondary heat exchanger.

[hawker238]

Is there any adverse effect on fuel quality, or is it keep seperate?

[Cobra412]

Not sure what your asking here Hawker.  The only thing your doing is pressurizing the tanks.  Putting that type of air source in won't affect the quality of the fuel.

[hawker238]

I think I got it.... thanks guys.

[Pyro]

Total tankage is correct, I just don't have it broken out into the 3 tanks.  I'm guessing I just temporarily plugged in the total fuel into one tank because I didn't have a breakout of the different tank capacities and then forgot about it.

[niklas]

Originally posted by Tilt
In AH there is one fuel tank modelled for the Lavochkins


All tanks were aluminium with several layers of tar soaked cloth around them such that they were self sealing. Further exhaust gases were flushed through the tanks to deny them of any oxygen.

There was no self-sealing mechanism for the Lagg, La, and probably for the even lighter Yak Series.
YouŽre right about the exhaust gas system however.

Maybe iŽll manage to get a picture from the Me262 in the German technical museum. Afair they cut up the fuel tank. There you can see very well how a self sealing fuel tank looks like...

niklas

[HoHun]

Hi Niklas,

>Maybe iŽll manage to get a picture from the Me262 in the German technical museum. Afair they cut up the fuel tank. There you can see very well how a self sealing fuel tank looks like...

Here it is :-)

http://www.x-plane.org/users/hohun/Me262FuelTank.jpg

Regards,

Henning (HoHun)

[niklas]

ah no, i mean they really cut up the fuel tank and you can see how thick the wall was. Afair it was at least 2 inch thick, filled with the stuff that reacts with the fuel to seal it.

For the La-series:
ThereŽs no way that soaked cloth layers of  ~8mm thickness total would give you a self sealing mechanism. ThereŽs no stuff that reacts with the fuel in it, and imagine a hit by a .50 : The diameter/wall thickness ratio would be ~1:1, no way that the tank could be sealed this way.

The wall design of the fuel tanks is only a protection against splitter fragments or direct hits for the La. The exhaust gas system is what should prevent fire and explosions. But no self sealing system.

niklas

[Tilt]

Originally posted by niklas
There was no self-sealing mechanism for the Lagg, La, and probably for the even lighter Yak Series.
YouŽre right about the exhaust gas system however.

niklas

To correct you with a full description ..............

Lagg3 did not have self sealing fuel tanks

La 5 models

"
 the tanks were made from aluminium/magnesium alloy overlaid with four layers of phenol-formaldehyde resin impregnated fabric to a thickness of 8mm. In the event of bullet damage the resin fabric acted as a self sealing agent within 10-15 secs of coming into contact with the fuel"


La7 which went beyond the tar soaked cloth of other models ........



"
The self sealing could  seal a bullet or splinter hole in 15 seconds. Its bottom part consisted of 5 layers -  the first was 1 mm thick gasoline resistant rubber, the second was was a 3mm thick soft rubber, which swelled quickly once exposed to gasolene, sealing the puncture, the 4th and 5th were two layers of 1.5mm thick cord fabric lined with an outer layer of 1.5mm fuel resistant rubber.

The top and side walls were protected by two layers offuel resistant rubber with 1.5 mm cord fabric between them."

Hence we see that the under side of the tank had better self sealing protection thna the rest of it. Of course certain hits would produce a level of damage that could not be sealed.........

We can opionnate on the effective ness of rounds at various calibres/ranges etc but the above is a matter of record.

[Bodhi]

Not all "self sealing" tanks are 2 inches thick, as a matter of fact, the US is approximately 5/16" thick, and contains a gel like material that hardens on contact with fuel.  Having removed, inspected and repaired numerous fuel tanks on 17's, 25's, 26's 51's, f6f's, f4u's, and others, I am confident in saying that the system is very efficient, but the tanks are EXTREMELY heavy.  Lastly, these tanks are not so self sealing if punctured numerous times in teh same area, and as they are mostly pressurised with outside ram air, an exploding round can and will "blow them up"