going down? - flight techniques

Discussion in 'CineStar FAQ - Tips and Tricks' started by Bryan Harvey, Feb 27, 2013.

  1. Bryan Harvey

    Bryan Harvey Member

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    Wonder if it would be worthwhile to start a new forum category just on flight techniques.

    I find that a lot of the reveal shots I like to do require a nice steady climb to altitude, then I often want to get my machine back near the ground as fast as possible for a reset. Also I find that buffeting on descent, (even though I try to stay out of my prop wash) forces me to abandon most of the descending shots I try during return to base. So if I just want to get my machine back to base in a hurry, is it OK to chop the throttles (say 15-20%?) and drop really fast, or is there danger of loss of control? I find myself hesitant to come down too fast, but sometimes it seems to take forever to return.
     
  2. Jim Swanson

    Jim Swanson Member

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    It takes a lot of practice to master shooting while coming down. I'm ok at it but nothing like Tabb, Jeff, and others. If I want a shot coming down, it sometimes works to reverse a shot going up... in the edit room.

    Just my opinion but if you a buffeting the copter you're going too fast on the descend. It takes a lot of energy to stop a fast descent and if your lipo is low on voltage (or the battery is old) you might find yourself crashing rather than soft landing. Ask me how I know.:(

    A fast descend might work from 50 feet because you have not built up momentum, but higher up takes more energy to stop your falling rock.

    jim
     
  3. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I've only ever been able to get moderately smooth descents if I come down with flight path angled off to one side to escape the "dirty air" and possible vortex ring effects.

    As to the rapid descent, I'm not sure you save much in battery power, because you have to put so much throttle in to stop the descent -- plus, as you say, there is the risk over the oversho--kerrunch..... ;)

    Andy.
     
  4. Joe Azzarelli

    Joe Azzarelli Active Member

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    While probably not as much of a problem with our helicopters, 'settling with power' can be catastrophic with the real copters. The issue is blade angle of attack with respect to relative wind. When descending rapidly you add the up wind vector (opposite of the copter's direction) to the horizontal wind vector created by the blade spin. This results in the same thing as if you had blades with larger pitch, which is that it takes more power to cut the air. This is why it takes a lot of power to stop a fast descent and if you are at the end of a flight the power demand can drop the battery voltage below the alarm limits.
    With real copters it is possible to stall the blades and lose lift just when you need it most - that is, close to the ground. The cure is forward motion to add the translational horizontal vector to the relative-wind-vector-mix thereby effectively decreasing the pitch.

    In short, if you have to drop fast, keep some forward motion. Both this issue and keeping the bird out of its own turbulent air will allow you to arrest the descent with less pucker factor.

    You may have also noticed the opposite effect: when ascending it seems like you need less power than when hovering. This is because in a climb with the down wind vector the effective blade pitch is less, making for less air resistance and the motors are naturally spinning faster.

    The more you know...
     
    Scott Strimple likes this.

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