Thread: Question Double horse 9116 Heli
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Old Dec 24, 2011, 01:41 AM
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Hi Mike and welcome,

I'm 48 years old, so I am probably nearer to your age group (I assume), and I too played with r/c planes as a kid, control line stuff mainly (Cox P38 actually), then life took over and I forgot about it. Now I'm earning some decent money and have no kids, and I thought I'd re-visit my childhood, with a large enough disposable cash flow to match my wants and desires.

The DH9116 is a helicopter that YOU have to fly, it will hover "hands off" for a little while, but not for long, like a 3.5ch co-axial heli. It's because of the 45 degree balance bar and the "pendulum effect" having a large impact on it's flight characteristics.

Anyway, because of the rear rotor, the heli will have a lean to the left to counter the torque of the main blades and motor, ideally it should be manually adjusted by lengthening or shortening the right servo link (I think, looking from the tail end) from the servo arm to the swashplate (you may not see the screw threads, but they are there), a half turn one way or the other and a quick test flight will give an indication of how much or less it needs to go. Same with the reverse drift where you adjust the left servo link. If you hold the heli and look at the servos from the rear of the heli, and get the blades spinning, then apply the relevant stick direction, you will see which servo and link that makes the heli move in a particular direction, that is the link you need to adjust. It can be done via the trims, but you may loose those settings if the batteries are replaced in the TX (for me this usually re-sets the TX back to factory settings, but in another forum members case, as you most likely have read, it hasn't).

As per taking off, how far would you estimate you get the heli off the ground when you notice these actions. The ground effect (that can make the heli drift in reverse and to the right in most cases) is most prominent within double the height of the total width of the main rotor blades, hence the need to get it above approx. 2 ft from the ground before attempting to go straight into a hover. All heli's no matter how expensive or cheap, have this inherent problem, it's to do with main rotor backwash, that creates uneven air tubulence and pockets of instability, but it's increasingly apparent the slower you attempt to take off. The downdraft of air from the two blades isn't uniform, it's quite "choppy". This is also prevalent in proper life sized helicopters. I suppose that is one reason for multiple rotor blades, to generate more lift with the same restrictive rotor head speed, to provide an even, less tubulent, and hence smoother, downward thrust for when hovering near the ground or during landing (I'm only guessing though logical deduction and reasoning and will stand corrected if someone else can explain the more appropriate reason, we'll probably get a short lesson in physics to boot). With all the heli's I own, except the co-axials, hovering is the the most difficult thing to master, to get a heli to hover well, not just at altitude, but inches from the ground. It's not impossible, just pretty darn difficult at the beginning. You need to anticipate what it is going to do by watching the subtle clues in it's flight, and move the sticks gently, rather than reacting with sharp movements to the sticks when it may already be too late. It's a "feel" thing and you'll know when you've got it or getting it, because you'll no longer be crashing as often and every time you fly it you'll just keep getting better and better, and your confidence will sky rocket proportionally.

I try not to adjust anything in the settings or manually on any heli, just the occasional trim adjustment, but I choose to rather fly around an issue, that way, if something slips or comes out of adjustment, I have the knowledge and experience to correct it and get it to the ground safely, rather than panic, drop the throttle and let it fall to the ground, which as you can imagine, can have disasterous consequences. We had a saying in the Aust. Army that I think equally applies to flying helicopters, "train hard, fight easy". I think if you start to learn to fly thinking or anticipating that something will go wrong, when it does, you'll be just that little bit mentally and/or physically prepared to do something about it sooner.

Mick.
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Last edited by stormforce; Dec 24, 2011 at 03:48 AM.