Tuesday, April 30, 2013

Beginner RC Helicopter & Quadrocopter

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By Gabriel Staples
Written: 13 Jan 2013
Last updated: 3 Dec 2016
Update History (newest on top):
-3 Dec. 2016, updated dead link to micro heli (now linked to "v911" search results on eBay), and updated links to some other small parts too
-6 Oct. 2013, added links to micro quadrocopters

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For those of you who have tried a 3-Channel micro helicopter or two (ex: virtually any helicopter that you might see at a mall), you are probably ready to try something a little bit better.  Well, don't go out quite yet and spend hundreds on a 6-Channel fully acrobatic collective pitch heli.  Rather, get a nice single-rotor 4-Channel beginner micro heli that can take some abuse while still teaching you more skills.  Once you master a micro 4-Channel heli, then take the step up to a several hundred dollar 6-Channel helicopter, and start flying slowly and carefully as it will be much more difficult still than the 4-channel heli.

So, which one to buy?  Well, I have the HobbyKing FP100 ($29 + shipping) (also see the "v911" eBay links below) (shown to the right), and I love it! It flies very well, gives you those extra skills you need while providing more challenge and capability, and yet is still so light that it is durable and can take quite a few crashes without breaking.  And if you break it? --you can buy spare parts!

How is this different from a 3-Channel Helicopter? 
A 3-Channel helicopter has a left stick which controls throttle, and a right stick which controls pitch and yaw.  There is no roll control, and pitch is extremely limited, since it is done simply via a tiny horizontal propeller near the tail which spins to create lift and slightly raise or lower the tail, thereby providing forward or aft movement.  A 3-Channel heli, therefore, is very limited in control authority, and can rarely go faster than a walking speed.  Another serious limitation is that they usually use infrared transmitters, which have a very short range, and are affected by sunlight.  Therefore, they are usually only indoor helicopters due to their ultra limited control (inability to counter even the slightest wind gusts), and infrared antennas which are susceptible to interference from the sun.  (Note: infrared transmitters are usually identifiable by a small, usually red, plastic cover near their top, instead of an antenna).

So, what is the extra channel on a 4-Channel helicopter?  
A 4-Channel helicopter, on the other hand, is highly maneuverable in comparison
to a 3-channel helicopter.  For a 4-Channel heli, the left stick controls throttle (up and down stick movement) and yaw (left and right stick movement), and the right stick controls pitch (up and down stick movement) and roll (left and right stick movement).  Whereas with the 3-Channel heli you were extremely limited and had only 4 degrees of freedom (pitch and yaw rotation; and up and down and forward and aft translation), with the 4-Channel heli you now have a fully-functional helicopter with 6 degrees of freedom (pitch, roll, and yaw rotation; and up and down, forward and aft, and left and right translation)!  How does this work?  Well, instead of the tiny horizontal propeller at the tail used to induce a very slight amount of pitch control, you have a conventional helicopter tail with a vertical tail rotor, and a main rotor with cyclic pitch controlled via a swash plate and two ultra micro servos.  In other words, through a specialized rotor head setup, a plastic mechanism in the rotor, called a swash plate, is actually tilted in various directions in order to cause the main rotor blades to pitch up and down as they rotate, thereby creating more or less lift in just the right locations throughout the rotation, so as to induce helicopter pitch and roll via gyroscopic precessional forces and the resultant thrust vectoring (want more info about helicopter control?  Visit here:  https://sites.google.com/site/electricrcaircraftguru/page-6-helicopter-control-explanation-gyroscopic-precession).

In other words, a beginner micro 4-Channel helicopter can now strafe rapidly left and right, and pitch forward or aft enough that you can get it to go as fast as a rapid sprinting speed.  Not only that, but the radio transmitter now uses a conventional antenna and has a range close to 100 ft.  Outdoor flying with the FP100 is easily possible in winds up to ~5 mph, and rapid flying and minor stunts (no loops, rolls, or inverted flight, however) can also be performed!

Note: the bar in the picture above, which lies above the main rotor blades, is called a flybar.  In "beginner" 4-channel designs, this flybar is at a 45 degree angle to the main blades.  This effectively creates a natural pitch and roll stability, or a slightly self-stabilizing tendency, in the helicopter in the roll and pitch axes--similar to what dihedral or polyhedral does for an airplane in the roll axis.  More aerobatic helicopters (such as 6-Channel helis) either have a 90 degree-oriented flybar, or no flybar at all (note: having no flybar requires a 3-axis rate gyro sensor computer-stabilization system, however)!  So....the FP100 truly is a fully functional, yet still an excellent beginner helicopter!

And how good of a deal is this?  Well, this $29 helicopter from HobbyKing comes to ~$50 with shipping, but would cost you over $100 to purchase a similar helicopter elsewhere!  Don't believe me? Check this out:
Nearly identical heli here for $110.

Oh, and by the way, it comes with *everything* you need!--heli, radio, built-in servos and receiver, 2 batteries, and even a cheap little USB charger!  Want to upgrade and get more batteries?   See below for the link to the additional batteries I purchased for just over $1 each.  I had to modify the heli to make it work with these batteries, so if you want the details of that modification, comment below.  With my modification, the heli still works with the old batteries (the ones it came with) though too.  Want to charge up to 18 or more batteries all at once?  See the links below.  I use a couple special harnesses (items 3 and 4 in the list below) to charge all 14 of my FP100 batteries at once, on a single charger, in only one hour!  Pretty crazy right?  Here's the concept of how I do it; it's called "Parallel Charging."  Make sure to read my entire Parallel Charging article before you attempt this process, however, as it requires a solid understanding, unless you want to damage your batteries and possibly cause a fire.


Lastly, here are some other excellent, economical 4-channel micro beginner helis I'd recommend:
-HobbyKing HK-190:  http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=18746&aff=281904 UPDATE (dead link), just use the HobbyKing "FP100" link above, or this Ebay link instead: eBay search for "v911" (the same exact helicopter) (cost: $20~$40, with *FREE* shipping!)
--Specific example: "WLtoys V911 RC Helicopter Drone Radio 4CH 2.4G Single Blade Gyro RTF US NB7C", $20.54 + $9.99 shipping - comes with the 4-Ch helicopter, Tx, charger, and micro LiPo x 2
-Xheli's H995, V911, or 9958:  http://www.xheli.com/4fixmicro.html 


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4-Channel Quadrocopters (added 6 Oct. 2013):  So, with the recent craze for micro quads, and with the fantastic technological leaps that have been made in MEMS (microelectromechanical systems) sensors, and on-board stabilization and processing, I thought I better put a link to a micro quad or two as well!


The picture to the left is called the "UDI 6 Axis Stablized UFO Quadcopter," and I own one!  It is a fantastic flier, and frankly, it is much better than my FP100 helicopter I bragged about so much above.  It can handle much more wind (up to ~10mph max), go much faster (hard to tell, but perhaps 30mph???), has way more thrust (climbs like a rocket), and can do flips at the push of a button (though sadly, manual flips are NOT possible, as the sticks control pitch and roll angles directly and it is angle-limited, via its firmware [on-board flight controller code], to 25~30 deg max in pitch and roll).  I'd like to add that it's name is misleading, as it's not really a "6 Axis" anything.  Rather, it has 3-Axis stabilization and 6-Degree of Freedom control.  I know it has a 3-Axis gyroscope sensor, so perhaps the "6-Axis" claim means it also has a 3-Axis accelerometer sensor too, but I am unsure.  Anyway, it can be purchased on Amazon Prime for only $36 here!

-Another option is the Syma quadcopter for $34.49 on Amazon Prime here.

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Here are the links of extra things I recommend, as described above:
  1. Nice charger - Thunder AC680, $55 with shipping: http://www.hobbypartz.com/73p-ac680-accharger.html
  2. LiPo-safe (fireproof) charge sack, ~$3, or this smaller one, ~$2.  These are always a good idea to use when charging.  Place all your charge harnesses and batteries into this bag while charging.
  3. Pico Parallel harness, $2 each (each harness does up to 6 batteries, so get 3 or 4 of these harnesses)
  4. JST Parallel harness, $5 (DEAD LINK, see replacement links below) this is necessary in order to plug in to your charger your 3 or 4 (or more....up to 6 max with this harness) Pico parallel harnesses above. Assuming you had 4 pico parallel harnesses above and one of these JST parallel adapters, you could charge 6x4 = 24 of these micro LiPo batteries all at once! 
    1. UPDATE: new link: eBay search for "jst parallel"; ex: here's one for $1.81 with free shipping [great deal]; or: eBay search for "banana jst parallel", ~$6~$10)
    2. OR you can make your own charge harness using something like this (Male JST Battery Pigtail 12cm Length (10pcs/bag)) and this (Banana Plugs (non-gold) (10pairs/set)), in order to plug multiple Pico Parallel harnesses above in parallel with each other and then into your charger.
  5. Pico plug extensions, $2.50 - get a pack of these to use as plugs for modifying your two existing batteries, and the heli.  Cutting an extension in half allows you to use it as a plug.  Solder the female plug (I am describing the gender of the plastic parts, not the metal pins) onto your heli, and a male plug onto each of the 2 batteries that the FP100 came with).
  6. Turnigy nano-tech 160mAh 1S 25~40C LiPo Pack, <$1.50 each - get as many of these as you want.  I recommend 6 or more for non-stop flying!
  7. Super sticky velcro, $2.50/meter for a 3" wide roll - nope, not all velcro is created equally.  This stuff is better and has a stickier, more reliable adhesive backing than anything I have ever used before.  It is required to velcro your new batteries above onto your slightly modified heli.
  8. Make yourself a good little battery voltage checker.  Most battery checkers are powered from the battery whose voltage they are measuring, but they don't function well (if at all) on a single-cell LiPo battery.  Therefore, you'll need external power for your battery checker.  For 1S LiPos I just use this cheap 7 Function Digital Multimeter from Harbor Freight Tools (shown below).  It is listed as $5.29 on their website, but I got it for free using a coupon, and I've seen it discounted many many times for ~$3.  It works surprisingly well for such a cheap device, and I've compared it against a nicer digital multimeter when measuring a variety of DC voltages (V), as well as resistances (Ohms) and diodes (forward Voltage drop), and I've found it to be much more accurate than I would have thought.  The test lead receptacles take 4mm banana plugs/bullet connectors, so you can plug your battery into a Pico Parallel harness, then plug that into the JST Parallel harness, and plug that into the multimeter, to easily test your 1S LiPo voltage.  Remember, for LiPo batteries, 3.0V/cell is empty, 3.7V/cell is ~20% full, and 4.2V/cell is 100% full.  



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4 comments:

  1. I love your teaching style because you mention each thing in detail which will definitely easy for beginners to understand.

    ReplyDelete
    Replies
    1. Thanks for the comment, and I'm glad I can help! I hope you enjoy reading many of my other articles too.

      Delete
  2. hello gabriel.....i have started to code arduino based quadcopter...i have mpu6050 sensor, 1000kv A2212/13 bldc motors, 30A escs, 11.1 v 2650mah lipo, arduino mega, flysky fsia6 tx rx do you have any tips for me to code?

    ReplyDelete
    Replies
    1. Hi, good luck with your project. The best advice I can give you is that Google is your friend, the Arduino Forums and Stack Overflow are your friends, and my article titled "The Power of Arduino" has lots of really good links at the bottom that I think you will find quite helpful as you progress. What you are undertaking is a lot of work and is by no means a trivial task.

      Delete

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