Take off weight verses landing weight

[Ballast]

I realise that there are lots of factors involved such as wind, runway length etc etc. but what is the general difference between max take off weight and max landing weight (without landing overweight) given for example that a B747 can take off at around 320 tons.. .. .ie. how much weight would it have to lose to land back at the airport of origin?. .. .Just to answer a pub argument in which I say that, in general, a loaded aircraft is too heavy to land at its max take off-weight.

[Intruder]

A 747-400 can take off at just under 397 tonnes, and land at just over 302 tonnes.. .. .The certificated weights depend on go-around limitations, brake capacity, structural limitations, analyses of fatigue, and a lot of other factors (some regulatory, some engineering).

[Ballast]

How much of the 397 tonnes is fuel, and am I correct in thinking that the capability to dump fuel has been removed/made optional on some aircraft?. .. .Thanks for the reply

[Hot Rod]

Some examples:. .The L-1011-500 has a max takeoff weight of 231 tons and max landing weight is 167 tons. The weight can lowered by fuel dumping at a rate of ca 2,5 tons/minute. That will give you 25 minutes to get down to max landing weight in case of a quick return.. .The A330-200 has a max takeoff weight of 230 tons and a max landing weight of 182 tons. The fuel dumping is optional on that airplane and without it you have the option of a lot of time (hours...) in a holding or an overweight landing which has too be a smooth one.... .The L-1011-500´s empty weight is about 110 tons (with crew and catering) and 302 passengers weights about 28 tons which leaves about 93 tons for fuel. . .The A330´s has an empty weight of about 120 tons (with crew and catering) and 371 passengers weights about 34 tons with luggage. That leaves about 76 tons for fuel.

[Intruder]

Up to 163 tonnes of fuel in the 747-400 (173 with the tank in the horizontal stabilizer). Basic airplane weight is about 158 tonnes, so the fuel and cargo/passengers vie for the rest.. .. .The -400 still has fuel dump capability, but it may take an hour to dump from max TO weight to max certified landing weight.

[Pegasus77]

Since you are calling yourself "Ballast".... considering throwing yourself out of the plane when the weight needs to be decreased for landing in an emergency?? <img border="0" title="" alt="[Big Grin]" src="biggrin.gif" /> <img border="0" title="" alt="[Big Grin]" src="biggrin.gif" />

[Pegasus77]

But added to that... the A320family (and I guess most other airliners) are certified to land with 600fpm (say without flare) at max landing weight, and with 360fpm at max takeoffweight. You can make an overweight landing, and I will in an emergency... fully depends on the situation.. .. .Only be aware of the higher moment of the aircraft, and start flaring a bit earlier.