Engineering topics
Publications and source records attributed to Pahle, Joe.
This paper contains information about the potential benefits and drawbacks of aircraft wake surfing. Wake surfing benefits have been measured and published previously; this paper presents the first known results obtained using a civilian business jet and an ADS-B data link.
The National Aeronautics and Space Administration (NASA) Armstrong Flight Research Center completed a series of research flights to better understand the challenges of aircraft wake surfing using civilian airplanes and commercial avionics. Airlines and air cargo carriers have identified uncertainty about increased passenger/crew discomfort due to noise and vibrations as a potential obstacle to the widespread adoption of aircraft wake surfing. To measure the effects of wake surfing on passenger ride quality, NASA instrumented a business jet with cabin noise and vibration sensors. The airplane was then flown under control of an experimental autopilot at multiple locations within the wake of a similar airplane. This paper presents a summary of the measurements collected on those flights, an assessment of passenger discomfort correlated with wake surfing performance benefits, and qualitative evaluations collected from passengers aboard during the research flights.
The National Aeronautics and Space Administration (NASA) Armstrong Flight Research Center (Edwards, California) completed a series of research flights to better understand the challenges of aircraft wake surfing using civilian airplanes and commercial avionics. The research flights sought to demonstrate significant fuel savings by a pair of business jets engaged in automated wake surfing using commercial off-the-shelf avionics to the fullest extent possible, including a 1090-MHz Automatic Dependent Surveillance - Broadcast (ADS-B) data link. A NASA Gulfstream C-20A airplane (Gulfstream Aerospace, Savannah, Georgia) was flown as the trail airplane within the wake of a NASA Gulfstream III (G-III) airplane. This paper presents a summary of the fuel savings measured during those flights.
These slides are the companion to the paper on the ACT experiment flown using a G-III autopilot and ADS-B datalink.
Many theoretical and experimental studies have shown that aircraft flying in formation could experience significant reductions in fuel use compared to solo flight. To date, formation flight for aerodynamic benefit has not been thoroughly explored in flight for large transport-class vehicles. This paper summarizes flight data gathered during several two ship, C-17 formation flights at a single flight condition of 275 knots, at 25,000 ft MSL. Stabilized test points were flown with the trail aircraft at 1,000 and 3,000 ft aft of the lead aircraft at selected crosstrack and vertical offset locations within the estimated area of influence of the vortex generated by the lead aircraft. Flight data recorded at test points within the vortex from the lead aircraft are compared to data recorded at tare flight test points outside of the influence of the vortex. Since drag was not measured directly, reductions in fuel flow and thrust for level flight are used as a proxy for drag reduction. Estimated thrust and measured fuel flow reductions were documented at several trail test point locations within the area of influence of the leads vortex. The maximum average fuel flow reduction was approximately 7-8%, compared to the tare points flown before and after the test points. Although incomplete, the data suggests that regions with fuel flow and thrust reduction greater than 10% compared to the tare test points exist within the vortex area of influence.