How much does a second seat add to empty weight of fighters?

[riggerrob]

How much does a second seat add to the empty weight of a jet fighter or jet trainer?
Similarly, how much does a second pilot detract from payload (bombs and fuel)?
We are talking about fighters that were originally designed as single-seaters (F-5, F-16, F-18, Rafale, Tejas, etc.), but were later modified to accommodate a second pilot.

 

[Archibald]

Usually, 1000 to 2000 pounds of fuel go away. And the guns, too.

 

[CV12Hornet]

The two-seat Rafale B is 772 pounds heavier than the single-seat Rafale C. Similarly, the F-15B was about 800 pounds heavier than the F-15A. In terms of fuel lost, the F/A-18B lost 7% of its fuel load and the F-16B 17%.

 

[H_K]

The two-seat Rafale B is 772 pounds heavier than the single-seat Rafale C.

And loses 400 liters of fuel.

 

[zen]

The extreme case is the Harrier T which is something like 1,500lb

 

[thefrecklepuny]

I did read some years ago in a book on the F-15 that the Eagle despite being primarily a single-seater was designed to accommodate a 2nd seat with zero fuel sacrifice.

 

[F-2]

F-2a empty weight 21003 lbs
F-2b empty weight 21237 lbs
F-2a max fuel 1225 gallons
F-2b max fuel 1043 gallons

 

[paralay]

Su-27 empty weight 17276 kg, fuel weight 9220 kg
Su-30 empty weight 18860 (MKK) - 19660 kg (MKI), fuel weight 9640 kg