Dumping Fuel

Is there a way to do this?

I have not done it myself but I think I read in the forums something about if the buttons are pushed to no allow fueling and then the crossfeed is opened and pumps are on that it will vent the fuel overboard.

It was something like that anyway.

Here is the thread I was thinking of:

http://forums.eagle.ru/showthread.php?t=58665&highlight=fuel

Crash. :)

hmm.. interesting question. Leaving the APU running drains fuel, I used to do this a lot in the KA-50 when one engine was out to reduce overall weight

hmm.. interesting question. Leaving the APU running drains fuel,

i have scoured the internet and my publications looking for any mention of a fuel dump system on the A10 Warthog, I cannot find any:huh: .

Understanding that aircraft normally have to meet a criteria of weight when they land I would expect it to have a dump system, I know all naval aircraft do..., large helicopters do also... but maybe the A10 because it can carry so much and is made to run on 1 eng,1 rudder and 1 elevator...naaa:cry: It has to have a dump system. I doubt that we will ever need it in the sim though:music_whistling:

You are killing me with hard questions stop already:surrender:

The A-10 doesn't have a fuel dump. Cali might know more specifics on it.

yeah, but at about 400lbs/hour it wont matter that much in an emergency :music_whistling:

Well, it's better than nothing...

Found it! The T.O. 1A-10A-1 manual states in the emergency section under landing emergencies, single engine failure or fire:

"External tank jettison is highly recommended for both performance and handling considerations."

There you have it. The procedure for dumping fuel in the A-10 is to jettison your external fuel tanks. The manual mentions nothing about any aircraft capabilty of dumping fuel from own internal tanks. ;)

As a side note, many commercial jet aircraft do not have the ability to dump fuel. ie the Bombardier CRJ's (same engine family as the A-10) and at least some versions of the A320. In the event that weight is needed to be reduced prior to landing, you have to simply burn it off.

The A-10 doesn't have a fuel dump......

Yes it does - ask the 9M331 operator politely if he would just nick a wing on the fly-by :P

LOL Lobo, nice way to describe the 'fuel dumping system' on the A-10C. :D

We don't have a fuel dumping system on the 737 either.

In our training we often end up with too much fuel + payload in an emergency resulting in a weight that is higher than Maximum Landing Weight. So what do we do in this case?

If you do not have a time critical situation you burn off fuel, for example in a holding.

If you do have a time critical situation you try to burn off as much fuel as you can, but you start preparing for an emergency landing and accept that it will be overweight. Of course there is nothing about that landing you will know for sure, but you do know that on top of the MLW there is a safety margin.

So, if you land 1000kgs overweight, the aircraft will not break in half, nor will the landing gear break. But what about 5000kgs overweight? You can't know for sure.

So we prepare for an emergency landing. Cabin gets ready. Everyone in the back head on their knees and cabin crew ready to evaucate when we have come to a standstill.

It's up to us then to land the aircraft as smoothly as possible to prevent as much damage as you can.

In a time critical situation its either that or die.

In the end we rather have one broken plane and 186 passengers plus crew in one piece and living on to tell about it, than a broken plane and all dead cause you didn't want to do an overweight landing. ;)

Same goes for military aircraft without a dumping system in a time critical situation, I presume.

I didn't realise that there was a maximum landing weight for aircraft. I assumed if it was light enough to take off, it was light enough to land.

Makes since, there's alot more force when landing than when taking off. What is the maximum landing weight for the A-10, and is this modelled in DCS? I've landed plenty of times with nearly maximum weight, full payload and combat fuel.

I didn't realise that there was a maximum landing weight for aircraft. I assumed if it was light enough to take off, it was light enough to land.

This is true for some aircraft, mostly small ones.

Usually Maximum Takeoff Weight is higher than Maximum Landing Weight.

Certification regulation states that MLW may never be higher than MTW.

As you pointed out yourself, forces on the aircraft are higher upon landing due to touchdown, which generates a momentarily increased G-loading.

Maximum Takeoff Weight (as defined by the factory, so do not confuse this with performance limited weights which result in possible lower takeoff weight, due to limitations by weather conditions, runway lenght available, etc) is, among other things, based on engine performance and wingloading and of course structural limitations.

Maximum Landing Weight is usually based on structural limitations alone.

I can't find a MLW for the A-10, but a book I have states 22.860kgs for maximun takeoff weight (pg. 267 Illustrated Encyclopedia of Aviation part 3), while its empty weight is 11.300kgs (note that this might not be a fixed value for every A-10C. It usually depends on systems on board).

So, the MLW of the A-10 will at least not be higher than 22.860kgs.

A real life example. Our 737s usually have a MTW of around 72.000kgs while MLW lies around 66.000kgs IIRC.

The question wether its modelled in the sim; I just tried to make a hard landing with a fully loaded aircraft and my gear broke. So yes it seems to be modelled. :D

Usually Maximum Takeoff Weight is higher than Maximum Landing Weight.

Certification regulation states that MLW may never be higher than MTW.

 

As you pointed out yourself, forces on the aircraft are higher upon landing due to touchdown, which generates a momentarily increased G-loading.

 

Maximum Takeoff Weight (as defined by the factory, so do not confuse this with performance limited weights which result in possible lower takeoff weight, due to limitations by weather conditions, runway lenght available, etc) is, among other things, based on engine performance and wingloading and of course structural limitations.

 

Maximum Landing Weight is usually based on structural limitations alone.

 

I can't find a MLW for the A-10, but a book I have states 22.860kgs for maximun takeoff weight (pg. 267 Illustrated Encyclopedia of Aviation part 3), while its empty weight is 11.300kgs (note that this might not be a fixed value for every A-10C. It usually depends on systems on board).

So, the MLW of the A-10 will at least not be higher than 22.860kgs.

 

A real life example. Our 737s usually have a MTW of around 72.000kgs while MLW lies around 66.000kgs IIRC.

 

The question wether its modelled in the sim; I just tried to make a hard landing with a fully loaded aircraft and my gear broke. So yes it seems to be modelled. :D

Thanks for the explanation!

To add: There's also a Maximum Taxi Weight or sometimes called Maximum Ramp Weight. This might be slightly higher than Maximum Takeoff Weight.

It's usually based on structural loading and friction/torsion limitations for the gear.

The A-10 doesn't have a fuel dump. Cali might know more specifics on it.

A-10's can't dump fuel, I worked on A-10 fuel systems for 6 years. The only way to dump fuel is to use it. MVSGas is right.

@ tusler, the crossfeed valve doesn't vent fuel overboard. It allows you to feed between tanks. The A-10 only has 4 internal tanks, 2 main tanks behind the pilot and 2 wing tanks. It can carry 3 External tanks, but they only use them to ferry the jets places.

EDIT: However the A-10 can vent fuel from a vent port on the underside of the jet. It's not used to dump fuel, it only vents fuel when there is a problem. I could go more into this, but I'm 100% sure it's not added in the game.

It's the gray tube inbetween the 2 black ones on the back.

What's dumb is we had to change them all the time cause they would get small cracks. It was a waste of money, cause it was a vent, it had no pressure on it.

Is its main purpose an overflow valve or pressure relieve valve for the fuel tanks? For example when fueling or to provide an exit for the fuel due to density issues by temp changes?

You got me curious now. ;)

Certification regulation states that MLW may never be higher than MTW.

Not always - certainly not if the aircraft is capable of dumping fuel.

Is its main purpose an overflow valve or pressure relieve valve for the fuel tanks? For example when fueling or to provide an exit for the fuel due to density issues by temp changes?

You got me curious now. ;)

The vent valves main purpose is to allow air/fuel to escape when the tanks are full of fuel and the fuel expands due to weather conditions..ie heat. This prevents the wings from undue internal pressure which could cause a rupture or increase the likelyhood of fuel leaks. I'm not sure about the A10 but alot of larger aircraft that have fuel in the wings use this vent system to move air from the left wing to the right wing and vice-versa...this is for when the aircraft enters a turn the fuel that moves to the outer part of the wing tank cause higher pressure so to relieve that pressure in that particular tank it is ported to the other wing tank throught the vent system. The vent valve is a self contained pressure actuated valve and cannot be selected by any switches to open or close.

Is its main purpose an overflow valve or pressure relieve valve for the fuel tanks? For example when fueling or to provide an exit for the fuel due to density issues by temp changes?

You got me curious now. ;)

The vent tube is just connected to the vent box. Vent box is used for both pressure relive and overflow... AFAIK, I have never worked on the A-10

EDIT: However the A-10 can vent fuel from a vent port on the underside of the jet. It's not used to dump fuel, it only vents fuel when there is a problem. I could go more into this, but I'm 100% sure it's not added in the game.

 

It's the gray tube inbetween the 2 black ones on the back.

 

What's dumb is we had to change them all the time cause they would get small cracks. It was a waste of money, cause it was a vent, it had no pressure on it.

Quick question...does the A10's fuselage tanks contain bladders for the fuel?? On the F18 for example the 4 fuselage tanks have bladders, if a bladder springs a leak and leaks into the cavity between the bladder and the fuselage it drains out of a fuel vent on the bottom of the aircraft...whichever vent it comes out of lets you know what tank is leaking and needs the bladder changed. Is this what the vent in the picture above is for on the A10 or is it actually the vent for the wing tanks?

Yes, it uses bladder-type tanks

The one on the photo, the same one Cali was talking about, should be the way for the vent box to release fuel or pressure overboard to help maintain system proper pressure.

See Cali, crew chiefs know some stuff :D

The vent valves main purpose is to allow air/fuel to escape when the tanks are full of fuel and the fuel expands due to weather conditions..ie heat. This prevents the wings from undue internal pressure which could cause a rupture or increase the likelyhood of fuel leaks. I'm not sure about the A10 but alot of larger aircraft that have fuel in the wings use this vent system to move air from the left wing to the right wing and vice-versa...this is for when the aircraft enters a turn the fuel that moves to the outer part of the wing tank cause higher pressure so to relieve that pressure in that particular tank it is ported to the other wing tank throught the vent system. The vent valve is a self contained pressure actuated valve and cannot be selected by any switches to open or close.

That's one reason, but actually the main reason is that as fuel is used, a corresponding volume of air needs to replace the fuel. The vent allows air into the tank. If there was no vent you'd create a partial vacuum in the tank which the pump has to work against... until the vacuum increases until it can't anymore and you get fuel starvation.

I'd imagine a reduced fuel pressure might cause cavitation in the fuel pump also.

Not always - certainly not if the aircraft is capable of dumping fuel.

Isn't it technically impossible to have a higher LW than a TOW? You're never gaining weight during a flight, only loosing it due to fuel burn.

So how can aircraft be certified for a higher MLW than its MTOW?

How would a fuel dumping installation allow for a higher MLW? The fuel dumping installation is going to dump fuel -> therefore reducing gross weight of the aircraft. It will create a situation that will be a from an overweight situation to a weight equal to or lower than MLW.

How is this related to MLW certification?

In other words, could you illustrate how a fuel dumping installation on an aircraft raises its MLW (even to values above its MTOW)?