31. It is designed to fly at subsonic speeds and photograph the earth from above 60, 000 feet. 32. Variable geometry would improve maneuverability at subsonic speed , but at the cost of decreased fuel tank capacity. 33. Because of noise restrictions, it operated at subsonic speeds between Dallas-Fort Worth Airport and Washington's Dulles Airport. 34. The termination shock is the point in the heliosphere where the solar wind slows down to subsonic speed . 35. At low speeds ( subsonic speeds ) increases in static pressure are however limited to a few percent. 36. Boeing designed the plane to have a 750-mile ( 1, 200-kilometer ) range and fly at subsonic speeds . 37. Thus, scramjets do not have the diffuser required by ramjets to slow the incoming airflow to subsonic speeds . 38. This led into a single large duct with three-part variable-profile walls that slowed the intake air to subsonic speeds . 39. Although I never heard of any subsonic speed that allows that, I'm not sure whether 2 Mach is mandatory. 40. The only wasted sound power is that emitted radially ( and, at subsonic speed , forwards ) from the engine.