Aerial refueling with external tanks

[Mud]

It seems that when you refuel with external tanks, these tanks also get filled.

 

Is there a way to prevent this?

[Eddie]

Yeah, stop refuelling when you have the desired amount of fuel.

[CEPEGA]

There is a refuel panel on the left side, there you can disable refueling external tanks. Look in the manual for info on this.

[Mud]

Haha Eddie, that one even works involuntarily when doing my best to stay connected. I'm improving though, 3-4 connects for a complete fill at the moment.

Edit: Does that effect chicks in tow though? If you complete a refueling, will your wingman automatically go next or do you always have to order him to get to the tanker anyway?

 

Cepega: I only saw buttons to disable fill to the internal wing and main tanks. But I'll go dig in the manual.

Edited July 28, 2011 by Mud
Chicks in tow

[CEPEGA]

Sorry was my fault. I understood the manual wrong. You can only disable refueling an damaged internal tank.

 

Sorry mate :doh:

[Mud]

No worries :) It's one of the best parts of this sim I think, after 6 months I'm still learning new things on a daily basis.

[Eddie]

Seriously, just stop when you're done. If you hit the NWS switch on the stick, it will disconnect from the boom.

 

External tanks should be the last filled. Fill order should be main tanks, wing tanks then externals if fitted.

[sobek]

Seriously, just stop when you're done. If you hit the NWS switch on the stick, it will disconnect from the boom.

 

Just curious, IRL you can tell the boom operator to give you x amount of fuel, right?

[Mud]

I just did a test, and from what I can tell, my external wing tanks (wasn't carrying centerline tank) get filled before my internal tanks get filled.

 

I have a track of it if need be, but it's fairly big.

[Snoopy]

Just curious, IRL you can tell the boom operator to give you x amount of fuel, right?

 

You are correct sir....

 

Per the C-1.....If you want to stop transfer from externals (to the wings/mains) or refueling the externals you just have to turn off the External Tank Switches on the Fuel System Control Panel.

 

EXTERNAL TANK SWITCHES.

Two external tank switches (Figure 1-9), placarded EXT TKS,

are located on the fuel system control panel. One switch is placarded

WING and OFF, the other is placarded FUS and OFF.

WING and FUS supply auxiliary DC essential bus power to

pressurize the external tanks, using bleed air. The fuel is transferred

to the main and wing tanks until external tanks are empty

or not transferring fuel. However, if the left or right main tank

low level switch is actuated due to low fuel, external fuel, if

available, will automatically transfer to the main tanks even if

the external tank switches are OFF.

 

FUEL SYSTEM OPERATION.

Normally, fuel system operation is automatic except for selecting

external tanks. Themain andwing tank boost pump switches

are positioned to L and R. The tank gate switch is positioned to

CLOSE. The crossfeed switch is positioned to OFF. With the

battery switch in PWR, the DC boost pump is energized when

the APU switch is positioned to START, or either throttle is forward

of OFF, and the left main boost pump is inoperative. The

DC boost pump supplies fuel to the APU and the left engine.

When the left and right AC busses are energized, the left and

right main and wing tank boost pumps will operate. External

tank fuel will be transferred to the internal tanks as fuel is used,

until the external tanks are empty. The wing boost pumps will

then supply the respective engine with fuel until the wing tanks

are empty, at which time the wing tank boost pumps will automatically

shut off. The main boost pumps will then supply the

respective engine with the remainder of the fuel in the airplane.

In the event of a wing tank boost pump failure, wing tank fuel

should gravity feed to its associated main tank, depending on

aircraft attitude and fuel levels. Gravity feed of a full wing tank

will not occur until the main tank fuel level is below approximately

600 pounds. Gravity feed of a partially full wing tank

will occur at lower main tank fuel level. Dual check valve units

in each wing tank gravity feed line prevent reverse fuel flow

from the main tanks back into the wing tanks.

When carrying external tanks, fuel sequencing will be as follows:

• External wing tanks

• External fuselage tank

• Internal fuel.

 

AIR REFUELING SYSTEM.

The aircraft can be refueled in-flight from a boom-equipped

tanker. The aircraft is equipped with a UARRSI (Figure 1-2), located

forward of the cockpit. By positioning a lever on the fuel

system control panel, a flush (slipway) door, powered by the

right hydraulic system, folds down into the fuselage to expose

the air refueling receptacle and to provide a slipway to guide the

tanker boom.When the tanker boom is inserted in the receptacle,

the nozzle latch rollers are actuated to the locked position, and

refueling transfer commences. Fuel transfer through the receptacle

is distributed to the main and wing tanks, and to external

tanks if carried. Through use of the fill disable switches, located

on the fuel system control panel, fuel can be prevented from entering

any specific internal tank suspected of being damaged.

As each tank is filled, float-operated fuel shutoff valves within

each tank will close, preventing overfill.When refueling is completed,

the disconnect of the boom nozzle will normally be accomplished

by a signal from the tanker or by the receiver depressing

the air refuel disconnect/reset button (Nosewheel Steering

(NWS) button) on the control stick grip. An automatic disconnect

will occur when both receiver and tanker systems are

completely operational and one of the following occurs:

• Excessive fuel pressure occurs in the receiver fuel manifold

• Tanker boom limits are exceeded (see Section VIII).

Refer to Section VIII for air refueling procedures.

If the right hydraulic system fails, the spring loaded slipway

door will open when the air refuel control is set to OPEN. The

time for the door to open sufficiently to expose the receptacle

is improved by reducing speed and will occur within approximately

3 minutes at 150 Knots Indicated Airspeed (KIAS).

Aerodynamic effect will open the door sufficiently to expose

the receptacle lights and permit emergency "stiff boom" refueling

with or without a READY light. Applying boom nozzle

pressure on the slipway door should result in the slipway door

downlock engaging and a READY light. The LATCHED and

DISCONNECT light will not come on in this case.

[mvsgas]

Thanks

[Mud]

I can't make out any specifics (might be my bad) from the quote you posted, Paulrkiii. But from my testing, even with the external tanks switch(es) turned off, upon AA-refueling the external tanks still get filled before the internal ones.

 

So either there's no way to prevent them from getting filled first whatsoever, or it's not properly modelled in the sim. That, or I'm making a major donkey of myself here :)

 

Per the C-1.....If you want to stop transfer from externals (to the wings/mains) or refueling the externals you just have to turn off the External Tank Switches on the Fuel System Control Panel.

 

[Druid_]

You are correct sir....

 

Per the C-1.....If you want to stop transfer from externals (to the wings/mains) or refueling the externals you just have to turn off the External Tank Switches on the Fuel System Control Panel.

From the narrative you've provided & the diagram of the fuel system in the wiki its not clear if there is way to stop the refueling of external tanks.

 

I'd be surprised if there wasn't a way mainly due to the fact that if one external tank refused to accept fuel for any reason, you wouldn't want the other filling up. You might have to however if you were on a trail and didn't want to become tanker dependant.

 

 

 

 

So either there's no way to prevent them from getting filled first whatsoever, or it's not properly modelled in the sim. That, or I'm making a major donkey of myself here :)

Shouldn't really matter. Although I haven't tried this myself in DSC, in theory if you latch in ALL of the fill disable switches only the externals will fill. Disconnect from tanker at required fuel uplift, then switch on the External tank switches to pressurise the external tanks. All of the fuel from the externals should transfer to the main & wing tanks. Once complete switch off the ext tank switches.

[coweatyou]

If you don't want to refuel the external tanks you could always just jettison them before tanking.

[Mud]

If you don't want to refuel the external tanks you could always just jettison them before tanking.

 

That seems rather wasteful :)

[Dejjvid]

It's not, since you don't carry them into battle. The only reason for having ext tks is for pure transport, or to drop them well ahead of the battle area.

 

So if you have them, and don't want 'em filled. Drop them. If you wanna keep them, why not keep them filled? Makes no sense to me...

[Snoopy]

The ONLY reason we carry external yanks in real life is on our way to the AOR or for long flights, never in route on a combat mission. In 15+ years working A-10s I have never seen live munitions loaded and an external.

[Mud]

Makes complete sense. Yet the first mission of my campaign is a ferry mission, with no combat events or weapons carried apart from some AIM-9's in case.

 

My main question is not about the discomfort it causes for me in the mission, since there's none. It's more about knowing how this works in reality.

 

It would make more sense to me that the internal tanks get filled before the external ones.

Say you do have to jettison your stores for some reason, I doubt you want to dump the majority of your fuel.

Edited August 20, 2011 by Mud

[Druid_]

It would make more sense to me that the internal tanks get filled before the external ones.

Say you do have to jettison your stores for some reason, I doubt you want to dump the majority of your fuel.

As soon as you start filling your external tanks if they are pressurised then the fuel in them will immediately start transfering to your internal tanks (the only question is the rate which I do not know). Even if your main&wings are full, provided you have the ext tank switches ON, then your external fuel will deplete first. See my prev post if you don't want to fill to full but want to empty the externals.

 

You appear to be complicating this more than it needs to be. There are very few reasons to jettison your externals on a AAR trail, the main one being engine failure/shutdown. In which case IRL the tanker if required would assist you to a suitable diversion or change the refueling brackets accordingly.

[muamshai]

Just curious, IRL you can tell the boom operator to give you x amount of fuel, right?

 

I would just pull my throttle to idle without saying a single word in advance once I get the required amount of fuel :D