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Stupid & Lucky - A Beginners Tale
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<blockquote data-quote="Virtual1" data-source="post: 21797" data-attributes="member: 4084"><p>No GPS means its using the cameras and proximity sensors only. Low light means the front and down cameras aren't going to work well either. So you're flying with the front and bottom IR sensors and gyro/compass only. Basically only bottom and front collision avoidance will be working, no position holding at all. <em>Orientation</em> should still work (turn/pitch/roll should be very minimal) but <strong>drift</strong> is your problem because <em>position</em> cannot be detected, particularly backward and sideways. So to recap, dark + no GPS + wind = dangerous drifting.</p><p></p><p>The speed limits (like if you are in beginner mode) are relative to <em>ground speed</em>, and so a sudden gust should be fully compensated for even if the correction requires a large reaction that would otherwise exceed the speed limit it is following.</p><p></p><p>As you have already noticed in your post-event analysis, you made several bad decisions that compounded with each other and resulted in a high risk.</p><p>- night flying is always higher risk, although this risk is lower if you are <em>very familiar</em> with your environment. being over at a friend's house doesn't count. Your own back yard maaaybe. Overhead wires and thin leafless branches this time of year can be hard to see or notice during the daytime, and are extremely hazardous and difficult or impossible to see at night.</p><p>- wind, especially gusty, is a bad thing to have in combination with a restricted area, because you have less time to react to a gust to prevent being pushed into an obstacle even if you are aware of it being there. throwing in low light and loss of GPS disables most of the Spark's protective features, and leaves you on your own for the most part. It's not impossible, but there's a lot heavier burden on the pilot to maintain control.</p><p>- I've found IMU interference to sometimes be annoying but not a serious problem. In severe cases it can be trouble, but most of the time it goes away after the aircraft has moved a short distance, getting it away from the interference. Trying to take off from a picnic table for example, you might find the metal bars below the wooden deck mess with your compass, but the problems go away immediately after takeoff. Metal only affects the compass (which keeps you pointed in the right direction) - the accelerometer (which keeps your aircraft level) and gyroscope (which buffer the gyro and accel and improve their response time) are unaffected by nearby metals.</p><p>- IMU interference is actually more of a hazard when you <em>have</em> GPS. Without GPS (and specifically when you are close to the ground) it relies heavily on the cameras for orientation and the corrections it makes to the motors will always be in the correct relation to the direction you are facing, because it's just trying not to move, rather than trying to get to / stay in a specific coordinate. But when the GPS is up, the flight computer will try to keep your Spark parked in a specific <strong>coordinate</strong>, and if it feels it needs to adjust it will make a correction relative to the direction it <em>thinks</em> your aircraft is facing, (and no, GPS does not tell you which direction you are facing, only which direction you are <em>traveling</em>) so if the compass is wrong it will correct in the wrong direction. The cameras may still be consulted, but if you are very far off the ground the camera can't get enough precision to be useful. For example, if your compass is 90 degrees off right and it thinks you need to move West, it may move you North instead. Now the GPS realizes you are both East <em>and</em> North of where you ought to be, and so it corrects SouthWest, which takes it NorthWest. As you might imagine this results in your aircraft slowly curving away from where it wants to be, hopefully leaving the area of interference in the process... but it's likely to then head right back to the interference once it regains its bearings. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite3" alt=":(" title="Frown :(" loading="lazy" data-shortname=":(" /></p><p></p><p>The details are a lot to learn, you may just be better off adhering to "best practices" which are easier to remember and respond to.</p></blockquote><p></p>
[QUOTE="Virtual1, post: 21797, member: 4084"] No GPS means its using the cameras and proximity sensors only. Low light means the front and down cameras aren't going to work well either. So you're flying with the front and bottom IR sensors and gyro/compass only. Basically only bottom and front collision avoidance will be working, no position holding at all. [I]Orientation[/I] should still work (turn/pitch/roll should be very minimal) but [B]drift[/B] is your problem because [I]position[/I] cannot be detected, particularly backward and sideways. So to recap, dark + no GPS + wind = dangerous drifting. The speed limits (like if you are in beginner mode) are relative to [I]ground speed[/I], and so a sudden gust should be fully compensated for even if the correction requires a large reaction that would otherwise exceed the speed limit it is following. As you have already noticed in your post-event analysis, you made several bad decisions that compounded with each other and resulted in a high risk. - night flying is always higher risk, although this risk is lower if you are [I]very familiar[/I] with your environment. being over at a friend's house doesn't count. Your own back yard maaaybe. Overhead wires and thin leafless branches this time of year can be hard to see or notice during the daytime, and are extremely hazardous and difficult or impossible to see at night. - wind, especially gusty, is a bad thing to have in combination with a restricted area, because you have less time to react to a gust to prevent being pushed into an obstacle even if you are aware of it being there. throwing in low light and loss of GPS disables most of the Spark's protective features, and leaves you on your own for the most part. It's not impossible, but there's a lot heavier burden on the pilot to maintain control. - I've found IMU interference to sometimes be annoying but not a serious problem. In severe cases it can be trouble, but most of the time it goes away after the aircraft has moved a short distance, getting it away from the interference. Trying to take off from a picnic table for example, you might find the metal bars below the wooden deck mess with your compass, but the problems go away immediately after takeoff. Metal only affects the compass (which keeps you pointed in the right direction) - the accelerometer (which keeps your aircraft level) and gyroscope (which buffer the gyro and accel and improve their response time) are unaffected by nearby metals. - IMU interference is actually more of a hazard when you [I]have[/I] GPS. Without GPS (and specifically when you are close to the ground) it relies heavily on the cameras for orientation and the corrections it makes to the motors will always be in the correct relation to the direction you are facing, because it's just trying not to move, rather than trying to get to / stay in a specific coordinate. But when the GPS is up, the flight computer will try to keep your Spark parked in a specific [B]coordinate[/B], and if it feels it needs to adjust it will make a correction relative to the direction it [I]thinks[/I] your aircraft is facing, (and no, GPS does not tell you which direction you are facing, only which direction you are [I]traveling[/I]) so if the compass is wrong it will correct in the wrong direction. The cameras may still be consulted, but if you are very far off the ground the camera can't get enough precision to be useful. For example, if your compass is 90 degrees off right and it thinks you need to move West, it may move you North instead. Now the GPS realizes you are both East [I]and[/I] North of where you ought to be, and so it corrects SouthWest, which takes it NorthWest. As you might imagine this results in your aircraft slowly curving away from where it wants to be, hopefully leaving the area of interference in the process... but it's likely to then head right back to the interference once it regains its bearings. :( The details are a lot to learn, you may just be better off adhering to "best practices" which are easier to remember and respond to. [/QUOTE]
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Stupid & Lucky - A Beginners Tale