From BBCi:
"It is twice the size of a Lancaster bomber ...
It can refuel another aircraft in the air with 100,000 litres of fuel, more than the amount contained by two large petrol tankers.
The Ministry of Defence said it can refuel at a rate of 5,000 litres per minute, compared with a pump at a garage that delivers fuel at 40 litres per minute."
No mention of those eternal units of comparison, the football pitch and the London bus. How far would the big red public transporter travel on the contents of the Voyeur, for example?