Historical research guide · 1032 · 1993
Fusion-electric propulsion for hypersonic flight
H. David Froning Jr. · Robert W. Bussard
In one minute
In 1993, at the AIAA Joint Propulsion Conference in Monterey, H. David Froning Jr. and Robert Bussard proposed flying an aeroplane on fusion. Bussard’s own line of work is the starting point: hold a cloud of light nuclei in an electrostatic well and squeeze them together with voltage rather than with a magnet or a laser, until enough of them fuse. Choose the right light isotopes and the reactions give back charged particles and no neutrons at all, which is what makes the idea flyable — no neutron shielding, no activated airframe. From that the two authors build a propulsion argument. Reactions like these can be made to deliver several times the thrust per unit of fuel flow that burning chemicals gives, at engine thrust-to-weight ratios an aerospace plane can carry. The payoff they calculate is a several-fold gain in how much payload a single vehicle can put in orbit, and hypersonic flight that is easy on the environment it flies through.
Connection
Chapter 12 says the first bottleneck in every advanced-propulsion story is a small, dense source of energy, and this paper is one of the earliest places where that argument is made in aircraft terms rather than power-station terms. Chapter 8 gets the shape of the vehicle that follows: once the energy is aboard and the exhaust is charged particles rather than combustion products, the design question stops being how much propellant to carry and becomes how much power to handle.
From the source
Bussard’s studies show that the charged nuclei of certain light-element isotopes can be electrostatically compressed to a density sufficient for nuclear fusion to occur — that is, the confinement is done with voltage rather than with magnetic bottles or laser implosion.Abstract, first sentence
The fusion reactions available to those nuclei emit no neutrons and induce no radioactivity, which is the property that makes an airborne reactor plausible at all: no neutron shield to carry and no activated structure left behind.Abstract, second sentence
Such clean fusion reactions can develop four to eight times more engine thrust per unit of fuel flow rate than chemical reactions can.Abstract, third sentence
The engine thrust-to-weight ratios that go with those reactions fall in the three to six range, which is the band an aerospace plane can actually be built around.Abstract, third sentence
Applied to an earth-to-orbit aerospace plane, fusion-electric propulsion would give a two-fold to five-fold improvement in payload delivery efficiency over the chemical baseline.Abstract, closing sentence
The same propulsion would make environmentally favourable hypersonic flight achievable, because the reaction products are charged particles from light isotopes rather than combustion exhaust.Abstract, closing sentence; title
The way in
https://doi.org/10.2514/6.1993-2611How to cite it
H. David Froning Jr., Robert W. Bussard (1993) Fusion-electric propulsion for hypersonic flight doi:10.2514/6.1993-2611