Dynamic ram accelerator system
Dynamic ram accelerator operation permits operation with lower acceleration, permitting launch of acceleration sensitive payloads such as crewed vehicles. Operational cost is reduced, and reliability improved, by reducing or eliminating internal consumable parts. Relative motion between a projectile and propellant at entry to the ram accelerator enables initial ram combustion at relatively lower velocity. Valves may maintain separation between sections within the ram accelerator that contain different propellant compositions. Timing of valve opening and closing is coordinated to provide conditions suitable for ram combustion. Control over propagation speed of propellant within the system may be obtained using one or more of baffle shape, baffle spacing, propellant temperature, propellant pressure, propellant mixture, temperature of components such as baffles, and so forth. Before the projectile is launched, internal separators between sections are removed, providing an open path to the ram accelerator exit.
1 . A system comprising:
a pre-launch system comprising;
a launch tube having a launch tube entry and a launch tube exit;
a ram accelerator system comprising:
a first section having a first end and a second end, wherein the first end is proximate to the launch tube exit;
a second section having a third end and a fourth end, wherein the third end is proximate to the second end;
a first fill stage having a fifth end and a sixth end, wherein the fifth end is proximate to the second end and the sixth end is proximate to the third end;
a first valve between the fifth end and the second end; and
a second valve between the sixth end and the third end;
a gas control system; and
a control system in communication with the pre-launch system and the ram accelerator system, the control system to:
operate the first valve and the second valve to close at a first time;
operate the gas control system to fill the first fill stage with a first gas at a second time, wherein the second time is after the first time;
operate the first valve to open after the second time;
operate the second valve to open after the second time; and
after opening the first valve and the second valve, initiate operation of the pre-launch system to launch a projectile, wherein:
the projectile is launched such that as the projectile enters the first section, the first gas moves in a direction that is opposite to the projectile and past the projectile, resulting in a first relative velocity of the first gas with respect to the projectile that is a sum of a velocity of the first gas and a velocity of the projectile, and
the projectile is launched such that as the projectile enters the second section, the first gas moves in a same direction as the projectile, resulting in a second relative velocity of the first gas with respect to the projectile that is a difference between the velocity of the first gas and the velocity of the projectile.
2 . The system of claim 1 , further comprising an exit diaphragm proximate to an exit of a section of the ram accelerator system to a surrounding environment, wherein the exit diaphragm is penetrated by the projectile.
3 . The system of claim 1 , wherein the first section is evacuated before initiation of the pre-launch system to launch the projectile.
4 . The system of claim 1 , wherein the first section contains the first gas before initiation of the pre-launch system to launch the projectile.
5 . The system of claim 1 , wherein one or more of the first section or the second section are at a specified temperature before initiation of the pre-launch system.
6 . The system of claim 1 , wherein the first gas is at a specified temperature before initiation of the pre-launch system.
7 . The system of claim 1 , the ram accelerator system comprising at least one baffle tube section comprising a plurality of baffles.
8 . The system of claim 1 , the ram accelerator system comprising a plurality of baffles and a plurality of rails, wherein the plurality of rails are mechanically engaged to the plurality of baffles and the rails constrain movement of the projectile within the ram accelerator system.
9 . The system of claim 1 , the pre-launch system further comprising:
the gas control system to provide pressurized gas to the launch tube;
a third valve proximate to the launch tube entry, wherein the third valve is operable to provide an opening with a time-variable cross-sectional area between the gas control system and the launch tube; and
the control system to:
operate the third valve to provide:
a first specified mass flow of launch gas through the third valve and into the launch tube at a third time, and
a second specified mass flow of launch gas through the third valve and into the launch tube at a fourth time.
10 . The system of claim 1 , the projectile comprising a space vehicle.
11 . The system of claim 1 , wherein the projectile is stationary prior to the projectile being launched.
12 . A system comprising:
a pre-launch system comprising;
a launch tube having a launch tube entry and a launch tube exit;
a ram accelerator system comprising:
a first section having a first end and a second end, wherein the first end is proximate to the launch tube exit;
a second section having a third end and a fourth end, wherein the third end is proximate to the second end;
a first fill stage having a fifth end and a sixth end, wherein the fifth end is proximate to the second end and the sixth end is proximate to the third end;
a first valve between the fifth end and the second end;
a second valve between the sixth end and the third end; and
a plurality of baffles within one or more of the first section, the second section, or the first fill stage;
a gas control system; and
a control system in communication with the pre-launch system and the ram accelerator system, the control system to:
operate the first valve and the second valve to close at a first time;
operate the gas control system to fill the first fill stage with a first gas at a second time, wherein the second time is after the first time;
operate the first valve to open after the second time;
operate the second valve to open after the second time; and
operate the pre-launch system to launch a projectile, wherein:
the projectile is launched such that as the projectile enters the first section there is a first relative velocity between the first gas and the projectile,
the projectile is launched such that as the projectile enters the second section there is a second relative velocity between the first gas and the projectile, and
the second relative velocity is less than the first relative velocity.
13 . The system of claim 12 , wherein as the projectile enters the first section, the first gas moves opposite to and past the projectile, resulting in the first relative velocity between the first gas and the projectile that is a sum of a projectile velocity and a gas velocity.
14 . The system of claim 12 , wherein as the projectile enters the second section, the first gas moves in a same direction as the projectile, resulting in the second relative velocity between the first gas and the projectile that is a difference between a projectile velocity and a gas velocity.
15 . The system of claim 12 , further comprising an exit diaphragm proximate to an exit of a section of the ram accelerator system to a surrounding environment, wherein the exit diaphragm is penetrated by the projectile.
16 . The system of claim 12 , wherein the first section is evacuated before initiation of the pre-launch system to launch the projectile.
17 . The system of claim 12 , wherein the first section contains the first gas before initiation of the pre-launch system to launch the projectile.
18 . The system of claim 12 , wherein one or more of the first section or the second section are at a specified temperature before initiation of the pre-launch system.
19 . The system of claim 12 , wherein the first gas is at a specified temperature before initiation of the pre-launch system.
20 . The system of claim 12 , the ram accelerator system comprising a plurality of rails, wherein the plurality of rails are mechanically engaged to the plurality of baffles and the rails constrain movement of the projectile within the ram accelerator system.
21 . The system of claim 12 , the pre-launch system further comprising:
the gas control system to provide pressurized gas to the launch tube;
a third valve proximate to the launch tube entry, wherein the third valve is operable to provide an opening with a time-variable cross-sectional area between the gas control system and the launch tube; and
the control system to:
operate the third valve to provide:
a first specified mass flow of launch gas through the third valve and into the launch tube at a third time, and
a second specified mass flow of launch gas through the third valve and into the launch tube at a fourth time.
22 . A system comprising:
a pre-launch system comprising;
a launch tube having a launch tube entry and a launch tube exit;
a ram accelerator system comprising:
a first section having a first end and a second end, wherein the first end is proximate to the launch tube exit;
a second section having a third end and a fourth end, wherein the third end is proximate to the second end;
a first fill stage having a fifth end and a sixth end, wherein the fifth end is proximate to the second end and the sixth end is proximate to the third end;
a first valve between the fifth end and the second end;
a second valve between the sixth end and the third end; and
a plurality of baffles within one or more of the first section, the second section, or the first fill stage;
a gas control system; and
a control system in communication with the pre-launch system and the ram accelerator system, the control system to:
operate the first valve and the second valve to close;
operate the first section to evacuate;
operate the gas control system to fill the first fill stage with a first gas after the first and second valves are closed;
operate the first valve to open after the first fill stage has been filled with the first gas;
operate the second valve to open after the first fill stage has been filled with the first gas; and
after the first section has been evacuated and the first and second valves have been opened, operate the pre-launch system to launch a projectile, wherein:
the projectile is launched such that as the projectile enters the first section there is a first relative velocity between the first gas and the projectile,
the projectile is launched such that as the projectile enters the second section there is a second relative velocity between the first gas and the projectile, and
the second relative velocity is less than the first relative velocity.