Drop tank questions

[dooom]

Ok - I have a few to ask:

 

Are they loaded full or empty by ground crew? Do I need to max my fuel bar and request refuel as well?

 

I think I am supposed to still start the p51 on LH main tank - when do I switch to drop tanks?

 

How do I know the drop tank I am feeding from is approaching empty so I can switch tanks?

 

What is ideal cruise alt with drop tanks?

 

 

Thanks all! I read the manual and can't seem to find answers to these questions.

[WildBillKelsoe]

If they are loaded at start of mission, they are full. Once expired, drop them, RTB, and request rearming default loadout. This should put back on 2 fresh tanks topped off.

 

You look at the fuel pressure gauge. If it drops, or if you hear the engine sputtering, you immediately switch to the next available tank.

 

You use the drop tanks when you've approached the cruising altitude. I don't think there is a restriction for altitude with drop tanks, although you want to use them as soon as possible, specially on ferry/long range combat flights, and jettison them once approaching an engagement zone. Don't forget to switch back to the L.H. main tank before jettisoning the drop tanks.

 

As a side note, your order of usage should be:

1- RH drop tank

2- LH drop tank

3- Fuselage tank

4- L.H. Main tank

5- R.H. Main tank

 

There is a catch but can't remember it now, about the gallons circulating back to the left hand tank so this might save some fuel.

Edited June 16, 2013 by WildBillKelsoe

[dooom]

+1 Bill.

 

I notice the startup is quite difficult with drop tanks.. Should i start with LH Main and then switch in flight or fire the engine up with RH DT right away? I thought i recalled something about the DT only feeding via vacuum hose and no boost pump.

 

Thoughts?

[Merlin-27]

I believe the priority is to reduce the severely adverse effect the Fuselage tank has on CG immediately. Once that tank has been reduced a decent amount you can move to the drop tanks. I have read time and time again were combat pilots would NEVER want to get jumped with fuel in that center tank. Against a good pilot you were toast. Also in RL you would want to reduce the fuel level a little bit early on in the Left Main tank as your fuel vapor return leads there. You could actually recapture a small amount of your unburned fuel over the course of a mission. Like WildBill said, they would burn a drop tank until the engine started to sputter and then switch. After the drops were gone pilots would switch between the two mains every 10-15 minutes to keep the weight evenly distributed.

 

I have also read how some pilots used differing approaches but the fear was that you can't jettison the fuselage tank so it would spell disaster if it was full during an engagement. Apparently, several found out the hard way.

[-MadCat-]

From the F-51D Pilot Handbook:

 

Fuel Tank Sequence

Take-off and climb should be accomplished with fuel

tank selector handle at MAIN TANK L.H. because the

vapor separation line from the carburetor returns to

this tank. Fuel vapors flow from the carburetor to this

tank at the rate of approximately one gallon per hour.

At altitude, use fuel from fuselage fuel tank until 25

gallons remain, to have ideal CG condition for landing.

Then cruise on drop tanks alternately until they are

empty. Continue flight using both main wing tanks

alternately, to prevent wing heaviness, until they are

empty. Then use fuel from fuselage tank during landing.

Note

For transitional training flights, keep approximately

25 gallons of fuel in fuselage tank to keep CG of

airplane in optimum position for landing.

Another P-51 training manual talks about up to 10 gallons per hour of fuel vapor, depending on conditions.

 

One more word on the 25 remaining gallons.

Those are meant as a reserve, so when reaching the destination airfield you should ideally have those 25 gallons, plus the one or other gallon in the wing tanks, left.

By that you also keep the ideal CG condition, though I don't know if the DCS Mustang really has a forward CG without those 25 gallons in the fuselage tank.

 

MadCat

Edited June 17, 2013 by -=MadCat=-

[WildBillKelsoe]

+1 Bill.

 

I notice the startup is quite difficult with drop tanks.. Should i start with LH Main and then switch in flight or fire the engine up with RH DT right away? I thought i recalled something about the DT only feeding via vacuum hose and no boost pump.

 

Thoughts?

 

Negative. Do NOT initiate the startup with the drop tanks. Resist the urge. There is no booster pump for them, only 5 lb/sq.in pressure is maintained, you could starve the engine. Also, never perform run-ups under any tank except the L.H. main tank. Like Merlin-27 and madcat said, the fuel vapors and the return to L.H. main tank should be switched to any other tank once 25 U.S.Gal has been reached, then you alternate on a timely basis.