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Does power matter to maximize flight duration?

Discussion in 'Pro/Adv Discussion' started by DDW, Sep 15, 2015.

  1. DDW

    DDW

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    I've read a lot of posts about flight time, distance runs, etc. It seems (I could be wrong) that at least the long distance flyers go out and back at max possible speed. But what of us who just want to go out a couple thousand feet, maximize the time we can stay there, and head back? At some point doesn't it make sense to go slower (using less battery, I would think) rather than faster? These batteries have to work harder going faster, fighting wind, etc. right? What's a good compromise speed to maximize time aloft? (I understand that winds will have an effect here as well). My apologies if this seems like a silly question.
     
  2. Meta4

    Meta4 Moderator
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    If you were just going up, going faster drains the battery faster because you have to rev the motors faster.
    But the Phantom doesn't fly faster by revving harder. That would just make it climb.
    It goes fast by changing its pitch angle, to add more forward component to its motion.
    Flying fast doesn't use a lot more battery than just hovering and what it does use is more than made up by the shorter flight time it takes.
    Easy to test yourself ... try a lazy slow flight with a lot of hovering and compare your battery time to a fast flying session.
     
    D4T_PoM likes this.
  3. DDW

    DDW

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    Thanks, that makes sense. So I think basically the answer is that there is not much point in loitering to get where you're going. I hadn't thought about the lift component vs. pitch component.
     
  4. DroningOnAndOn

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    Just consider that when you are moving forward, a quad has no 'wing' like a plane or heli for free lift so it needs to put extra effort into both keeping the quad up and moving forward at the same time. This means you need to rev the motors harder to keep it up as well as keep it moving forward as less air stays under the quad (you need to physically move more air to accomplish the forward/upward movements). Additionally you have drag. The faster you go the more load it puts on the system and the less efficient the system becomes. So moving faster again drains a lot more energy from the lipo much more quickly. I would imagine that hovering is the most efficient thing a quad can do.
     
  5. Charles Winiarski

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    Agreed, the least draining (power related) is a simple hover with no lateral movement.
     
  6. Darmie

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    Yep.. Aka effective translational lift. Or close to it.
     
  7. TonG

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    Nice theory but you forgot the other half. If you are tilting your quad you split up the energy/force up in a horizontal and vertical part. The bigger the tilting angle, the bigger the horizontal force (bigger horizontal speed) but the lesser the vertical force.
    But the weight of the quad stays the same so by al lesser vertical force you have to rev up your motors to compensate for that.
    Put it simple, the faster you go horizontally, the bigger the angle, the more power your need!

    But there comes an other (very small?) factor into play. If a helicopter/quad has a lateral movement the propellers begin to act like a wing and producing an extra lift. I have red some articles about this. But how efficient this lift is and it really counts I don't know.


    By the way you always should keep another thing in mind. Maximising horizontal flying distance needs another power strategy then maximising flight time.