Set up your flight area to include cones or other markers spaced every 25 feet (or every 5 or 10 meters - an even number). You will use these markers as a guide to help you visually understand distances a you fly your sUAV. Make sure your indoor [1]or outdoor [2]flying area is properly set up and that you have taken all necessary precautions as outlined earlier in this guide.
Remember that if something goes wrong, THROTTLE DOWN and let your multirotor fall before it damages something or causes injury.
This exercise is as important for the Spotter as it is for you, the operator.
Once you are able to estimate distances visually, you a ready to begin estimating your distance vertically. There two ways, with the help of a spotter) to directly measure the altitude (height) of your sUAV when flying: using the Parallax GroundStation (if your ELEV-8 v3 is equipped with an XBee Radio for telemetry), or with an inclinometer [3]. But, with a little bit of knowledge and some practice, you should be able to reasonably estimate the height of your sUAV when you are flying. Estimating your Altitude is especially important because if you are flying outdoors, it is against the law to fly over 400 feet (122 m) Above Ground Level (AGL).
To practice estimating altitude, you will set up a marker or cone exactly 50 ft (15 m) away from you. During the practice, you will take off and land from that marker, and you will only fly straight up and straight down taking care to keep your sUAV directly over the marker.
Look carefully at the following image. It shows the angle you would be looking up for various altitudes:
The angle you are looking up at will help you determine the height of your sUAV. When you are looking up 30 degrees from the ground, the height of the object you are looking at is half as high as it's ground distance from you - if it's 50 feet (15 m) away, then it's 25 (7.6 m) feet high. When you are looking up at a 45 degree angle, an object's height is the same as it's ground distance, so if it started 50 feet (15 m) away from you and flew up 50 feet (15 m), you would be looking at a 45 degree angle. If you are looking up at a 60 degree angle, it's height is double the ground distance - if it started 50 feet (15 m) away and flew up to where you are looking up 60 degrees, it is 100 feet (30 m) high.
Notice that in the drawing above the operator and the sUAV make up the bottom side of a right triangle. Because it is a right triangle, we can use tangents to calculate distances from the angles we know. The tangent (tan for short) of an angle describes the relationship between the adjacent side of the triangle (how far it is from the operator to the sUAV on the ground) and the opposite side of the triangle:
Again, If you have a Spotter, fellow student or friend with you, they can use an inclinometer (a very simple tool to build) [3] or the sensors tab on the Parallax GroundStation (if your ELEV-8 v3 is equipped with XBees) to call out your altitude and help you know exactly how high your sUAV is as you practice.
Because you will also be descending and landing from higher altitudes, these exercises are also a good opportunity to practice your landing skills. Remember that as your sUAV descends, it gains momentum, and it will take increased throttle before you land to slow and stop its fall:
To practice estimating your altitude:
Once you have spent several hours practicing nose-out flight, you are ready to begin practicing flight with the multirotor in different orientations. You will begin by making short, simple flights with your multirotor oriented left-side in. Make sure your flying area is properly set up and that you have taken all necessary safety precautions as outlined earlier in this guide. Remember that if something goes wrong, THROTTLE DOWN and let your multirotor fall before it damages something or causes injury.
Links
[1] http://node/1205
[2] http://node/1206
[3] https://www.exploratorium.edu/math_explorer/howHigh_makeInclino.html