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Stopping the props mid-flight
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<blockquote data-quote="cozzykim" data-source="post: 65843" data-attributes="member: 6499"><p>There's also a misconception that the unpowered props will 'autorotate' on the way down and help with some lift, but they won't.</p><p>As any RC or full size heli pilot knows, to autorotate you have to be able to change the collective pitch so that the leading edge of the blades have the correct angle of attack to generate lift on the way down, basically by applying negative pitch.</p><p></p><p>The Spark props are fixed pitch and would try to rotate backwards on the way down. As the prop would be spinning backwards (which it can't anyway, see below*) it wouldn't generate appreciable lift because the airflow over it is in the wrong direction and wouldn't generate any appreciable pressure difference.</p><p></p><p>*This is all moot anyway, as the coreless motor magnetic resistance is too high to allow the airflow to spin the motors.</p><p></p><p>It's an expensive brick guys. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite9" alt=":eek:" title="Eek! :eek:" loading="lazy" data-shortname=":eek:" /><img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite7" alt=":p" title="Stick Out Tongue :p" loading="lazy" data-shortname=":p" /></p></blockquote><p></p>
[QUOTE="cozzykim, post: 65843, member: 6499"] There's also a misconception that the unpowered props will 'autorotate' on the way down and help with some lift, but they won't. As any RC or full size heli pilot knows, to autorotate you have to be able to change the collective pitch so that the leading edge of the blades have the correct angle of attack to generate lift on the way down, basically by applying negative pitch. The Spark props are fixed pitch and would try to rotate backwards on the way down. As the prop would be spinning backwards (which it can't anyway, see below*) it wouldn't generate appreciable lift because the airflow over it is in the wrong direction and wouldn't generate any appreciable pressure difference. *This is all moot anyway, as the coreless motor magnetic resistance is too high to allow the airflow to spin the motors. It's an expensive brick guys. :eek::p [/QUOTE]
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Stopping the props mid-flight