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Old Feb 09, 2013, 07:38 PM
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Philippines, NCR, Taguig City
Joined Feb 2013
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Rehashed newbie question about Translating Tendency

Hi! I already posted the same question on another RC forum, but I just want to cover more ground with my data gathering and reading. No need to be brash people, just a newcomer seeking enlightenment here.

Here goes.

I'm a newbie and making steady progress with hover training. I could already hold a hover inside a one meter radius for a short time and that's as close to steady as my pinch hold can get me right now (at least inside the sim) but so far, so good.

My question, or my problem rather, is about the perpetual newbie gripe which is the left drift during hover. I don't have a reference to what a normal left drift looks like/feels like as I'm a loner in this hobby and have no access to a mentor nor a flying buddy to give me tips.

Now, before anyone tries to shoot me for not reading about helicopter aerodynamics, I'd like to stress out that I've done my homework and have accumulated some general understanding about the physics of translating tendency and how to reduce it to an extent; either by mechanically tilting the head a little to the right or giving a few clicks of right trim. Some people mention that this drift goes away about at about 2-3 feet off the ground but it doesn't seem to go away in my sim.

I've already made sure of the points below:

1. creation of a new model with single servo 90 deg swash with 0 subtrim.
2. made sure gimbals are centered. the right gimbal (mode2) returns to exact center as shown in my tx (dx7s) monitor screen.
3. made sure the tx model inside phoenixrc is also calibrated properly.
4. the helicopter model is set up to 100% (advanced) inside phoenixrc.

I've included a recording of my phoenixrc session showing the left drift I'm talking about. Note that to make my point clear, I'm not putting any aileron at all, just throttle. I have about 3 clicks of right ail right now which sort of reduces the drift.

http://dl.dropbox.com/u/43917481/Slight_Drift_Left.pxr (phoenix 4)

Also, I've been reading this thread http://www.rcgroups.com/forums/showthread.php?t=1417633 which pretty much sums up my situation.

I understand that helis don't fly themselves and you have to constantly correct its movement but.... how normal is a "normal" left drift?

Thanks!
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Last edited by amerei; Feb 09, 2013 at 07:44 PM.
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Old Feb 09, 2013, 09:05 PM
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United States, AZ, Mesa
Joined Jul 2007
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This is simple. The helicopter in the recording is behaving normally. You are just throttling up with no adjustment after you take off. The helicopter is level on the ground, but it needs to be tilted slightly to the right to counter the tail, and you never put it in that position. When you do put it in that position, it should more or less stay there. After you lift off, you need to roll to the right just a bit, then then helicopter should go straight up if you did it right.

Once you have the helicopter in a hover, if it tries to roll (not slide, roll) to one side or the other, use aileron trim to fix that. Make sure your radio is calibrated properly - center the trims before doing the calibration.
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Old Feb 10, 2013, 04:13 AM
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Philippines, NCR, Taguig City
Joined Feb 2013
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Hi Jasmine. Thanks for replying. I guess I'd better just accept things as they are and have fun training/practicing until everything becomes second nature. I've attached a second recording, this time, I'm actively trying to hover. I still couldn't really counter the left drift upon take off but I'm able to get the heli to do a peaceful hover once I get a hold of the drift.

http://dl.dropbox.com/u/43917481/tail_in_hover.pxr

I'm also slowly trying to get into side-in hover in parallel with tail-in. Could you spare some tips on what to look for when doing side-in? In tail-in, I could visually see any inclination by looking at the skids before it takes a really big roll, but I'm having difficulty looking for inclinations during side-in. I normally take cues from the heli's shadow but this trick doesn't work all the time, especially when the heli is high enough to not cast any shadow on the ground.

much respect,
amerei
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Last edited by amerei; Feb 10, 2013 at 06:52 AM. Reason: added link
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Old Feb 10, 2013, 10:49 AM
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United States, AZ, Mesa
Joined Jul 2007
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Quote:
Originally Posted by amerei View Post
Hi Jasmine. Thanks for replying. I guess I'd better just accept things as they are and have fun training/practicing until everything becomes second nature. I've attached a second recording, this time, I'm actively trying to hover. I still couldn't really counter the left drift upon take off but I'm able to get the heli to do a peaceful hover once I get a hold of the drift.

http://dl.dropbox.com/u/43917481/tail_in_hover.pxr

I'm also slowly trying to get into side-in hover in parallel with tail-in. Could you spare some tips on what to look for when doing side-in? In tail-in, I could visually see any inclination by looking at the skids before it takes a really big roll, but I'm having difficulty looking for inclinations during side-in. I normally take cues from the heli's shadow but this trick doesn't work all the time, especially when the heli is high enough to not cast any shadow on the ground.

much respect,
amerei
Only advice is stop concentrating on the attitude of the helicopter. Concentrate on what it's doing. The reason I say that is every helicopter is different, and you should switch around in the simulator. The attitudes that work on one machine won't work on another one, so you don't want to be looking for certain angles. You need to develop the ability to instantly find whatever angle you need for the movement you want. It is hard, but stop trying to look at the angles of things - look at the whole machine. Try to understand what everything is doing as a whole. It takes a long time for that to become instinct.
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Old Feb 10, 2013, 04:46 PM
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Philippines, NCR, Taguig City
Joined Feb 2013
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Quote:
Originally Posted by jasmine2501 View Post
Only advice is stop concentrating on the attitude of the helicopter. Concentrate on what it's doing. The reason I say that is every helicopter is different, and you should switch around in the simulator. The attitudes that work on one machine won't work on another one, so you don't want to be looking for certain angles. You need to develop the ability to instantly find whatever angle you need for the movement you want. It is hard, but stop trying to look at the angles of things - look at the whole machine. Try to understand what everything is doing as a whole. It takes a long time for that to become instinct.
All points taken with no objections. Good heli wisdom there. Thank you Jasmine.

much respect,
amerei
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