Experimenter is a magazine created by EAA for people who build airplanes. We will report on amateur-built aircraft as well as ultralights and other light aircraft.
Issue link: http://experimenter.epubxp.com/i/96284
result in ground contact at these test altitudes. For example, an airplane flying 50 feet AGL at 150 knots will hit the ground in less than 6 seconds if the flight path is just 2 degrees below horizontal. Stay heads-up out there, and maintain a good external scan. Some of your runs will be low, slow, and dirty. Should it lose power, your airplane won't have a lot of excess energy (speed) you can convert into altitude (and time aloft). Consider this when selecting your ground course. Perfectly flat and clear is ideal, and you can't do any better than a long, off-duty runway. (Make sure you have the airport/control tower's permission and cooperation.) You should have plenty of clear surface both paved and unpaved. An additional advantage of an airport test site is that the airport survey map tells you exactly how long your run is. For a non-airport test site, check local government records to determine your exact test course length. Regardless of your test site, you should have a plan if things go wrong. If the engine stops, you won't have time to contemplate your actions. Base your plan on the topography, your airplane's capabilities, and the nature of the emergency. For example, you'd probably handle an engine stoppage different from a bird strike to the wing. Mentally rehearse your actions for every conceivable emergency. Low and slow is not the only flight configuration for concern. Low and fast means bad things happen faster. If your electric trim suddenly decides to run away nose-down, faster airspeed means less time for you to react. Start with a mid-envelope airspeed like your plane's typical cruise speed. Then fly progressively faster runs. Follow that with progressively slower runs starting from your first mid-envelope speed. Finally, fly legally. FAR 91.119 gives the minimum safe altitudes above people and buildings (but you should not be testing above them, anyway). When flying over sparsely populated terrain, you must remain at least 500 feet from any person, vessel, vehicle, or structure. No matter where you fly, even over barren terrain, FAR 91.119 says that if the engine quits, the minimum safe altitude is one that allows an emergency landing without undue hazard to persons or property on the surface. Give yourself plenty of room to turn around for the reciprocal heading run. Tere's no need to remain at the low test altitude during this repositioning. Next month we'll cover the data reduction and convert all those test run timings into true airspeed and calibrated airspeed, and then we'll correlate them to the observed airspeed readings. » Questions about flight testing for Ed? Send an e-mail to Experimenter@eaa.org with the words Flight Testing in the subject line, and we'll forward your questions to him. Ed Kolano, EAA 336809, is a former Marine who's been flying since 1975 and testing airplanes since 1985. He considers himself extremely fortunate to have performed flight tests in a variety of airplanes ranging from ultralights to 787s. Flight Testing webinars In September, Chad Jensen, EAA Homebuilders Community Manager, conducted the first of a series of webinars discussing flight testing of homebuilts. The first webinar focused on preparations for flight testing your homebuilt airplane and what to expect when planning your flights and flying your plan. You can view that webinar here. On Thursday, December 13, at 7 p.m. (CST), Chad will present the second installment in the series and will explore best practices and decision making while flight testing homebuilt aircraft. Space is limited and registration is required; sign up now to participate at www.eaa.org/webinars. EAA EXPERIM ENTER 45