Virtual Aerospike Engine

US 12,173,671 B2 · Single stage to orbit rocket engine

Virtual Aerospike Engine

An aerospike nozzle compensates for altitude, but its spike is a large hot surface that is hard to cool. This engine makes the spike out of gas: a straight column runs down the middle of the chamber, the burning propellant spins around it as a vortex, and past the nozzle the column tapers into a spiked wick. Below is the engine cut in half on a bench, built from the patent's claims.

US 12173671 B2
Column of gases, the virtual spike Vortex of reacted propellant Blanket and film coolant The near half of the engine is removed. The gas is drawn whole, so streamlines pass in front of and behind the column. The dotted ring on the pad marks where the edge of the exhaust lands.

What the patent lets you adjust

Sets the air pressure outside. The free edge of the exhaust opens as the air thins.
Shown here as a wider column, which leaves the vortex a narrower ring to exit through.
Measured off the chamber's radius. The more tangent the spray, the tighter the vortex winds.
116Blanket of gases
The three forms the patent names. As a stream it runs the full length, and the nozzle's film inlets are not needed.
112Ridges in the exit nozzle Remove them and the exhaust leaves still spinning.

Parts, by the patent's reference numerals

Taken from the patent

  • The three streams and their inlets. Column 118 through inlet 102, vortex 114 from main inlets 106, blanket 116 from inlets 104, and film coolant at the nozzle from inlets 108.
  • How each stream moves. The column is axial with minimal angular velocity. The vortex spins around it. The blanket is a vortex, a stagnant pocket or a stream.
  • Ridges or grooves at the end of the chamber or nozzle that make the gas leave along the axis.
  • The spiked wick at the end of the nozzle, formed by adjusting the column's pressure, velocity or angle, or the vortex.
  • An adjustable exit area through which the vortex leaves, and inlet settings that change with atmospheric conditions, in design or in flight.

Added for this figure

  • Proportions and layout. The patent says its dimensions are illustrative and gives no pressures. The inlet counts, the manifolds, the stand and the supply lines are this bench model's own.
  • Column width. The patent names the column's pressure, velocity and angle as the levers. It does not say how they change its width, so the slider sets the width directly.
  • Air pressure is the International Standard Atmosphere at the chosen altitude.
  • Exit open is the ring between the nozzle wall and the column as a share of the nozzle's exit, from the drawn radii.
  • Spin is the sine of the inlet angle: the share of the jet's speed that goes around the chamber. Streamlines then follow a free vortex, with axial speed set by the open area.
  • Schematic, not computed: how far the exhaust opens with altitude and how long the wick is. The direction is right; the amounts are not predictions.
  • Launch schedule. The patent leaves trimming the column against altitude to the designer or the flight computer. Simulate launch uses one schedule: the column is at full strength on the pad and falls in proportion to the air pressure outside as the engine climbs. Outside a launch the two sliders are independent.

Source: US 12,173,671 B2, granted 24 December 2024, claims 1 to 10 and the description of FIGS. 1A to 1D.