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fired, (often from a conventional gun), into the accelerator barrel, causing compression between the projectile and the barrel's walls. The barrel contains a pre-mixed gaseous fuel-air mixture. As the ram accelerator projectile compresses the fuel-air mixture, it is ignited and the combustion is stabilized at the base of the projectile. The resulting pressure differential generates a prodigious amount of thrust that can accelerate projectiles to in-tube Mach numbers greater than 8. Thus, if propellant mixtures with a
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292:. With a ram accelerator, the projectile is propelled primarily by the pressure generated by the reaction of the propellant gases burning just behind the projectile. This leads to constant pressure being put both on the gun and the projectile itself. Consequently, far longer barrels are possible than conventional guns, while still delivering a strong constant acceleration to the projectile.
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In a normal ramjet, air is compressed between a spike-shaped centerbody and an outer cowling, fuel is added and burned, and high speed exhaust gases are expanded supersonically out of the nozzle to generate thrust. In a ram accelerator, a projectile having a shape similar to the ramjet centerbody is
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To span a wide range in a typical ram accelerator system, multiple stages with propellants with different sound speeds are used to maintain high performance. Membranes or diaphragms that are easily punctured by the projectile are used to isolate the propellant stages. Each section is filled with a
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Ram accelerator technology has also been envisioned for military applications such as ultra-long range striking and intercepting capabilities against stationary and on-the-move threats. The fact that the projectile accelerates and travels at very high velocities makes it a perfect alternative to
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The chief advantage of a ram accelerator over a conventional gun is its scalability. In a normal gun, maximum pressure is exerted at the time of the charge ignition. As the projectile moves further down the barrel, the amount of acceleration upon the projectile decreases as the gas behind it
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230:) supersonically through the first diaphragm into the tube. Then the projectile burns the gases as fuel, because it is shaped like a ramjet or scramjet core, and accelerates under jet propulsion. Other physics come into play at higher velocities.
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could have such striking abilities against high alert threats. Such projectiles could even be integrated into railguns themselves to allow even higher acceleration at a cheaper cost and effectiveness against a wide variety of targets.
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Ram accelerators have been proposed as a cheap method to get payloads into space. Impulsive launched projectiles need some means to circularize their trajectory for orbit insertion, so
398:, Carl Knowlen; Adam Bruckner & Andrew J. Higgins et al., "Baffled-tube ram accelerator", issued 2018-11-20, assigned to University of Washington
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different fuel-air mixture chosen so that later sections have higher speeds of sound. As such, the ram can be maintained at optimal speeds of
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3–5 (relative to the mixture that it travels through) during its entire acceleration period. Ram accelerators optimized to use
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modes can generate even higher velocities (Mach 6–8) due to the ability to combust fuel that is still moving at supersonic speed.
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Technologies related to a ram accelerator for direct space launch applications are: two-stage gas guns (
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expands, eventually reaching amounts trivial enough that a longer barrel is no longer justified
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diaphragm at either end to contain the gases. The projectile is fired by another means (e.g., a
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Ram accelerators are currently used primarily for research into supersonic combustion. The
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It consists of a long tube (barrel) filled with a mixture of combustible gases with a
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warfare, giving it abilities to evade defense systems. Only systems such as
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mixtures) are used, muzzle velocities in excess of 8000 m/s are possible.
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combustion processes. It is thought to be possible to achieve
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or just a single projectile to extremely high speeds using
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119:. Unsourced material may be challenged and removed.
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410:Ram Accelerator | University of Washington
348:weapon was inspired by ram accelerators.
304:, such as those designed in the 1960s in
179:Learn how and when to remove this message
77:Learn how and when to remove this message
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271:Scramjet projectiles were tested in
117:adding citations to reliable sources
428:Pope, Gregory T. (March 1, 1994),
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203:-like propulsion cycles based on
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243:of 1000 m/s (e.g. fuel-rich H
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540:Momentum exchange tether
32:This article includes a
715:Beam-powered propulsion
600:Endo-atmospheric tether
61:more precise citations.
741:High-altitude platform
659:Blast wave accelerator
477:Non-rocket spacelaunch
396:US patent 10132578
215:with this technology.
213:non-rocket spacelaunch
799:Spacecraft propulsion
764:Megascale engineering
261:supersonic combustion
609:Projectile launchers
113:improve this article
288:Internal ballistics
759:Rocket sled launch
736:Buoyant space port
578:Dynamic structures
34:list of references
804:Artillery by type
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419:, retrieved
415:the original
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342:scram cannon
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306:Project HARP
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273:Project HARP
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111:Please help
106:verification
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53:Please help
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705:Spaceplanes
628:Mass driver
595:Launch loop
507:Space tower
500:Compressive
486:Spaceflight
383:Mass driver
234:Description
197:projectiles
59:introducing
793:Categories
700:Air launch
680:Slingatron
673:Mechanical
616:Electrical
439:2009-02-13
421:2018-12-07
279:Advantages
201:jet-engine
139:newspapers
654:Space gun
314:anti-ship
220:frangible
777:Category
754:See also
647:Chemical
638:StarTram
352:See also
334:coilguns
330:railguns
318:railguns
209:scramjet
169:May 2018
67:May 2018
731:Balloon
633:Railgun
623:Coilgun
535:Skyhook
521:Tensile
378:Coilgun
363:Railgun
302:rockets
267:Testing
228:railgun
153:scholar
55:improve
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332:, and
205:ramjet
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326:SHARP
160:JSTOR
146:books
40:, or
296:Uses
257:Mach
132:news
226:or
207:or
115:by
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