www.PSFmagazine.com | March-April 2019 | 25 24 | March-April 2019 | Powered Sport Flying FOOTHILL SPORT AVIATION Cameron Park CALIFORNIA WOODS AVIATION Watts Woodland Airport CALIFORNIA LONE STAR MAGNIGYRO Taylor Municipal Airport TEXAS MAGNI FLIGHT LLC Jack Edwards Airport (KJKA) Alabama CAPE COPTERS Cape Girardeau Municipal Airport MISSOURI MAGNI GYRO U.S.A. Perryville Municipal Airport MISSOURI MAKERS OF EXPERIENCE U.S.A. high-quality Italian products, likeMagni gyroplanes, in ITALIAN FLYING TECHNOLOGY MAGNI GYRO s.r.l. - Tel. +39 0331 274816 - Fax+39 0331 274817 - www.magnigyro.com- info@magnigyro.com Support Our Advertisers The relative wind encountered by the advancing blade is increased by the forward speed of the gyro, while the relative wind speed acting on the retreating blade is reduced by the gyro’s forward airspeed. Therefore, as a result of the relative wind speed, the advancing blade side of the rotor disk can produce more lift than the retreating blade side. (See the image to the right.) During forward flight the individual rotor blades, when compared to each other, are operating at unequal relative wind airspeed. This dissymmetry of relative wind increases at higher gyroplane airspeeds. And, if not somehow compensated, there would be higher lift on the advancing blade than on the retreating blade. This raises the question what is the effect of unequal relative wind on the advancing and retreating blades? Precession and blade cyclic ‘teetering’ action compensate for the dissymmetry of lift. So, it can be said there is no dissymmetry of lift. But there actually is a dissymmetry of relative wind. FOR 50 POINTS: NAME THREE EXAMPLES OF AUTOROTATION. You may have come up with more, but here’s three right off the top… 1. Maple tree seed (did you not read question one?) 2. An airplane in a flat spin and 3. When talking to newbies about gyros, I always like to tell them that helicopters become a gyroplane when their engine quits— pilot must lower collective and flatten blades to put the rotor in autorotation before it gets too slow. A gyroplane is always in autorotation. FOR 25 POINTS: WHEN DOES A GYROPLANE ROTOR BECOME A ‘WING?’ And the answer is…when rotor rpm is high enough for the rotor to lift the nose. My first gyro instructor (not my husband Greg, incidentally!) always said you don’t have to concentrate on the rotor tack. Look up, when you see the individual blades turn into a spinning blur, you’re probably ready to release the pre-rotator and give full throttle. Seconds later, the nose wheel will lift and the machine is ready for flight. The rotor tells the pilot it is a ‘Wing’ and ready to fly when it lifts the nose. FOR 25 POINTS: IN A RELATED QUESTION, HOW DOES A SPINNING ROTOR (DISK) CREATE LIFT? Our diagram provides a more extensive explanation, but simply put, lift is caused by the rotating wing deflecting the air downward. When the mass (total weight of all air molecules) of the air deflected downward equals the weight of the gyroplane, the gyroplane is in level flight. This is exactly what a fixed-wing airfoil does as well. See the images below. FOR 50 POINTS: WHY IS A GYROPLANE SO SENSITIVE TO WIND TURBULENCE? Ah, trick question! Gyroplanes are not that sensitive to the wind, to a point. Just think about it. The outer leading edge of a rotor is creating most of the lift by moving at speeds over 300 mph. So, a 20 mph wind gust is a much smaller percentage of the rotor’s relative wind and a lot less affected. But, a 20 mph gust on a fixed wing traveling at 100 mph is much more affected by that same wind gust. You can look at it as a rotor with a much smaller ‘wing’ area than a fixedwing. It has a much higher ‘wing loading’ and penetrates wind gusts much easier. It is absolutely more comfortable to fly in higher winds in a stable gyroplane compared to a fixed-wing. But, that’s not to say you don’t need more advanced skills to handle high winds. A low time gyro pilot obviously should not fly in high winds until his/her skill level matches the challenge. FOR 100 POINTS: DESCRIBE ‘DISSYMMETRY OF LIFT’ Well, my ‘go to’ source Wikipedia says dissymmetry of lift in rotorcraft aerodynamics refers to an uneven amount of lift on opposite sides of the rotor disc. It is a phenomenon that affects helicopters and gyroplane rotors in forward flight. My other ‘go to’ source, Greg Gremminger, has a little more involved answer. Try this on for size… dissymmetry of lift is a higher relative wind on the advancing blade than on the retreating blade. However, it might be more correct to refer to this as a ‘dissymmetry of relative wind.’ Production of lift. Airflow through the rotor system on a gyroplane.
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