26-minute familiarization video of a flight conducted without any airspeed references, only performance angle of attack cues:
https://youtu.be/r8XcXDHLIIM
No magic here. Just a good AOA/Energy Management system. Disclaimer: we generated the inset indexer video post flight from data, it's a bit jittery, particularly the slip/skid ball. There are several mis-speaks in the cockpit narration. No excuse, we'll do better in the future.
Reader’s digest version of how an AOA system should work for folks not familiar with our work:
System Requirements. For an AOA system to serve as a primary reference it must be accurate across the entire speed band of the airplane from Vmax to stall. It should measure actual AOA within 1/4 degree or better under static conditions and 1 degree or better under dynamic conditions. It must be responsive to high G pilot inputs and gust loads (better than 2G/second onset rates), but sufficiently damped and presented to the pilot as a “flyable” cue regardless of the wing it is fitted to. The system should accommodate flap position with proper sensors and a calibration curve for each flap setting, especially if the airplane has slotted flaps. Calibration curves should be normalized using data from within the same pressure field occupied by the AOA probe. For typical underwing locations, normalization should be based on data directly from the probe. Calibration points should extend from Vs to Vmax and should include EAS points for stall warning (based on FAR 23 criteria), an ONSPEED condition (Vref), L/Dmax and Carson’s speed. Use of multiple data points across the entire speed band of the airplane and regression analysis yield more accurate calibration curves.
Performance Cues. The parameters that an AOA display can convey to the pilot (visually and/or aurally) are Carson’s speed, L/Dmax, ONSPEED and stall warning. If a % lift display is also provided, weight adjusted maneuvering speed can also be determined. Maneuvering speed occurs at 100/aircraft G limit. For the 6G RV-4, this is a 17% lift condition. If the wing is generating more than 17% lift, the aircraft is below actual Va. L/Dmax occurs at 50% lift and ONSPEED occurs at 60% lift.
Energy Cues. From a general energy management perspective, a “flyable” system should also provide an easy means to determine Excess Specific Power, abbreviated Ps and pronounced “P sub S.” A simple, intuitive cue should tell the pilot if there is more thrust than drag or more drag than thrust for a given weight condition (actual gross weight times any load factor). If P sub S is negative, the airplane will either go down, slow down, or both, unless the pilot reduces AOA and/or increases power; assuming power is available and the ground doesn’t get in the way. If P sub S is neutral, thrust and drag are balanced, and the airplane achieves maximum sustained turn rate and minimum sustained turn radius—sometimes referred to as an “optimum turn.” An easy way to think of this is simply "bleeding, not bleeding" energy. Any slow tone means you bleeding energy--stop the bleeding by reducing AOA. If you are completely engine out, there is no "thrust" part of the equation, but the same "bleeding/not bleeding" push/pull logic applies if your objective is the best blend of glide and turn performance and optimum energy for approach/touchdown when maneuvering at low altitude. Accurate aural AOA cues convey essential performance and energy information to the pilot without the requirement to look inside the cockpit.
FlyONSPEED.org is a 501(c)3 non-profit, open source, all volunteer group dedicated to developing hardware, software and education resources for the EAB community. Our mission is to reduce loss-of-control mishaps, share lessons learned and have fun. We’d like to see a paradigm shift to folks “flying the wing,” knowing their energy state and maintaining positive aircraft control using proven military technology and techniques; and a data-driven approach to improving training.
Fly safe,
Vac
https://youtu.be/r8XcXDHLIIM
No magic here. Just a good AOA/Energy Management system. Disclaimer: we generated the inset indexer video post flight from data, it's a bit jittery, particularly the slip/skid ball. There are several mis-speaks in the cockpit narration. No excuse, we'll do better in the future.
Reader’s digest version of how an AOA system should work for folks not familiar with our work:
System Requirements. For an AOA system to serve as a primary reference it must be accurate across the entire speed band of the airplane from Vmax to stall. It should measure actual AOA within 1/4 degree or better under static conditions and 1 degree or better under dynamic conditions. It must be responsive to high G pilot inputs and gust loads (better than 2G/second onset rates), but sufficiently damped and presented to the pilot as a “flyable” cue regardless of the wing it is fitted to. The system should accommodate flap position with proper sensors and a calibration curve for each flap setting, especially if the airplane has slotted flaps. Calibration curves should be normalized using data from within the same pressure field occupied by the AOA probe. For typical underwing locations, normalization should be based on data directly from the probe. Calibration points should extend from Vs to Vmax and should include EAS points for stall warning (based on FAR 23 criteria), an ONSPEED condition (Vref), L/Dmax and Carson’s speed. Use of multiple data points across the entire speed band of the airplane and regression analysis yield more accurate calibration curves.
Performance Cues. The parameters that an AOA display can convey to the pilot (visually and/or aurally) are Carson’s speed, L/Dmax, ONSPEED and stall warning. If a % lift display is also provided, weight adjusted maneuvering speed can also be determined. Maneuvering speed occurs at 100/aircraft G limit. For the 6G RV-4, this is a 17% lift condition. If the wing is generating more than 17% lift, the aircraft is below actual Va. L/Dmax occurs at 50% lift and ONSPEED occurs at 60% lift.
Energy Cues. From a general energy management perspective, a “flyable” system should also provide an easy means to determine Excess Specific Power, abbreviated Ps and pronounced “P sub S.” A simple, intuitive cue should tell the pilot if there is more thrust than drag or more drag than thrust for a given weight condition (actual gross weight times any load factor). If P sub S is negative, the airplane will either go down, slow down, or both, unless the pilot reduces AOA and/or increases power; assuming power is available and the ground doesn’t get in the way. If P sub S is neutral, thrust and drag are balanced, and the airplane achieves maximum sustained turn rate and minimum sustained turn radius—sometimes referred to as an “optimum turn.” An easy way to think of this is simply "bleeding, not bleeding" energy. Any slow tone means you bleeding energy--stop the bleeding by reducing AOA. If you are completely engine out, there is no "thrust" part of the equation, but the same "bleeding/not bleeding" push/pull logic applies if your objective is the best blend of glide and turn performance and optimum energy for approach/touchdown when maneuvering at low altitude. Accurate aural AOA cues convey essential performance and energy information to the pilot without the requirement to look inside the cockpit.
FlyONSPEED.org is a 501(c)3 non-profit, open source, all volunteer group dedicated to developing hardware, software and education resources for the EAB community. Our mission is to reduce loss-of-control mishaps, share lessons learned and have fun. We’d like to see a paradigm shift to folks “flying the wing,” knowing their energy state and maintaining positive aircraft control using proven military technology and techniques; and a data-driven approach to improving training.
Fly safe,
Vac
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