Interesting Note on Stealth Aircraft

In this Aviation Week article on research into more making electronic systems on aircraft more efficient: (paid subscription required)

Goals of the Air Force Research Laboratory’s Integrated Vehicle Energy Technology (Invent) program include extending range and endurance 10-15%, increasing power and thermal capacity by 10-30%, overcoming cooling challenges in low-observable platforms, and reducing life-cycle costs.

Because the stealthy F-22 and F-35 dump their heat into the fuel, they are “flying Thermos bottles,” says Steven Iden, AFRL’s Invent program manager. The heat loads in the F-35 are up to five times what they are in the F-16, he says, and could increase by another factor of four in a future laser-armed fighter

...The Invent power and thermal management system will extract, store and reuse electrical power and adaptively use the heat sinks available, including fuel, low-observable ram air, and heat exchangers in the engine fan duct and the “third stream” provided by the Advent engine. This is a third flowpath introduced on Advent to vary the bypass ratio.


....

In the F-35, regenerative energy from the power-by-wire flight-control actuators is dumped into heavy resistor banks, which produces heat. For Invent, AFRL is looking to develop an “electrical accumulator” that would store the energy and use it to meet peak power demands from the systems, similar to a hydraulic accumulator.

(emphasis mine)

On further thought, this is not surprising, as a cooling scoop for external air is typically a non-stealthy feature, though the degree of the problem surprises me.

It restricts time spent on the ground at idle, and increases the unusable fuel in the tanks, as it has to be used for component cooling .