In rec.aviation.military KDR wrote:
snip
OK, could Sea Harrier FRS1 safely land vertically on the Invincible
class carrier in the South China Sea in mid-summer with two unused Sea
Eagles after a two-hour mission?

Was there any case the FRS1 had to jettison unused Sea Eagles before
landing on the carrier?

The trivial way would be to look up the weight of a Sea Eagle.
600Kg per.
So, 1200Kg.

The first site I found gave 2295Kg of fuel for a model of the harrier.

So, if it can land fully fueled, but without the eagles, then it can
land with about half and them.
Assuming no COG/... issues.