Quiet Spike entered the supersonic flight regime on October 20, 2006. Once the envelope was cleared through Mach 1.4 at 40,000 feet, a flight to investigate the near-field shock signature of Quiet Spike was performed. Another NASA Dryden test asset, the F15 NASA 837, was configured with pressure sensing equipment to probe the shock waves created by the F15B NASA 836 with Quiet Spike installed. The probing maneuvers, with the NASA 836 and NASA 837 in formation, were performed on December 13, 2006. In January 2007, the spike-extended envelope clearance was completed for flight out to Mach 1.8. Directly following spike-extended envelope clearance completion, the test team evaluated the static and dynamic structural envelope up to Mach 1.4 with the Quiet Spike in the retracted position. During the envelope expansion research test flights, the Quiet Spike was extended and retracted at flight conditions between 5,000 to 15,000 feet at approximately 225 KIAS. A flight test engineer in the aft cockpit initiated the Quiet Spike extension and retraction operations through a control panel. In addition to system status feedback available in the aft cockpit, the engineers in the Mission Control Center had instrumentation information available to assess the operation of the Quiet Spike mechanisms. Following both the extended and retracted envelope clearance out to Mach 1.4, the Quiet Spike transition capabilities were demonstrated with the aircraft at airspeeds up to Mach 1.4.

Structurally, the Quiet Spike was sound. Mechanically, the telescoping mechanism worked well. It looked very promising; it is an exciting technology. It’s only the first step. There are a lot of people in commercial aerospace looking into sonic boom mitigation. It would be incredible to get on a supersonic jet and get to wherever you are going in a quarter of the time, or half the time.

NTB: Is it in commercial use now?

Molzahn: It is not. This was just a developmental, one-step investigation into the feasibility of mitigating a sonic boom to the point where it might be feasible to implement it in a commercial application, to press forward with the possibility of supersonic flight in the commercial industry.

The readiness level of going on to a commercial airliner is not feasible. This was just the first step. This was an investigation into the technologies to see if it was feasible structurally to fly on the forward section of an aircraft. This would just be one piece of a supersonic jet that could fly over the continental US. A new airframe has to be developed for it; a commercial airliner can’t go supersonic. We would first have to get over the hump of getting a commercial airliner to go supersonic, and then move on to breaking the stronger shockwaves up into weaker shockwaves.

Looking into the aerodynamics of it, the Quiet Spike looked to match predictions, what it was hoped to do. There will be formal papers coming out in the near future with the data. But it looks like a feasible solution.

For more information, contact Leslie Molzahn at This e-mail address is being protected from spam bots, you need JavaScript enabled to view it