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Minimizing The Toilet Bowl Effect On Your Syma S107 Helicopter

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What is The Toilet Bowl Effect (TBE)

The Toilet Bowl Effect can be a problem experienced in flight susceptible to every coaxial RC helicopter available, not just the Syma S107 Infrared Helicopter. As the title of this page suggests, a coaxial 'copter that experiences the toilet bowl effect will somewhat, behave as if it had been caught up in a vortex or such as when flushing a toilet. The symptoms, are that of large circular movements whilst hovering, NOT of rotation about the axis of the heli.
The latter effect is due to yaw problems and cannot be fixed by the methods described below

The Problem Lies With The Balance Bar...

What causes TBE?

Syma S107 Helicopter Fly Bar

There are many alternative, (and incorrect) theories behind the causes of toilet bowl effect on micro coaxial model helicopters, however only one - the upper section of the rotor head, probably the flybar pivots but potentialy the top blade pivots. Please note the lower rotor has nothing to do with it and under no circumstance will cause TBE. Un-balanced blades, incorrect blade tracking, and improperly balanced balance bars also have nothing to do with and do not contribute to the toilet bowl effect.

What does the Balance bar actually do?

A very basic explanation of what the balance bar does is it automatically corrects the pitch angles of the rotor blades to stabilize the helicopter if it is pitching or rolling giving an almost live feedback to provide great stability.
In other words the fly bar is responsible for this "self correction" and for it to do its job correctly, it has to apply a change in angle to the rotors at precisely the correct time.

The Fix!!

The Flybar is stiff and binding on the pivot points in the head or on the ball links going from the flybar to the rotors.

Syma S107 HelicopterThe balance bar should be able to move freely with almost no resistance. It should only need the slightest touch to move it to its extremity. If the fly bar encounters resistance, then there will be an ever so slight delay in the auto correction of the rotors pitch. This will in fact cause, you've guessed it, TBE. Make sure the fly bar pivots are well lubricated with a silicon spray lubricant. DO NOT use water or petroleum based lubricants such as WD40. Using these will result in dust and dirt being attracted to the pivot joint and in the long run exaggerating the toilet bowl effect, not curing it. The other thing is when the two halves of the pivot are molded, often there is a seam where the two halves were joined. This seam can bind, causing unwanted resistance. If this is the case, then using Emory paper, smooth the joint down to reduce friction before lubrication.

If this doesnt work; replace the main assembly to eliminate TBE

Mayday mayday mayday! This is Romeo Echo Delta 5, we got way too close to the dining room table leg and we're going down. We need spares and we need them quick!

This set comes complete with balance bar and top blades. Replacing this part is extremely easy. Simply loosen one of the two horizontal screws at the top of the rotors to slide out the old piece. Replace and tighten the screws.
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S107 Helicopter Review
Honest and reliable review for the Syma S107 Helicopter.
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Other fixable problems you may come across flying the Syma S107 Helicopter.

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  • Reply
    Roxysteve Feb 23, 2012 @ 11:49 am | delete
    Nice and informative, and one for my maintenance manual, but I just came across another reason for this that if not addressed morphs into helicopter-racing-across-room-and smashing-into-stuff syndrome - a cracked pin in the upper rotor hub assembly.

    Briefly, this allows the rotor to move slightly so that the angle between it and the gyro bar decreases. Eventually the second pin cracks and the rotor can now float in three dimensions, leading to sudden onset uncontrolled-flight-into-face-itis. The good part is that you can actually get the helicopter into the air before the new behavior makes itself known, which ups the excitement factor no end. It's all fun and games until your whirlybird goes for your nose.

    The only cure is to replace the hub and to vow to quickly power off in a crash from now on to minimize the chances of doing the same damage again.

    If you have a Syma 107 that suddenly develops this behavior after a crash and the gryo seems to move freely, suspect a cracked pivot in the upper hub. If the rotor head can be advanced toward the gyro angle then you may have this kind of damage.

    Unfortunately, the only way to be sure is to remove the upper rotors and examine the pivot-bearing with a small probe.

    Additionally, the replacement part set linked to in the article does not include the hub assembly. You'll probably need to buy the entire shaft and either replace the one you have or dismount the hub from it as a replacement for your broken one.

    http://www.amazon.com/Syma-S107g-13-Helicopter-Replacement-Part/dp/B004N37Y8Q/ref=sr_1_1?ie=UTF8&qid=1330015708&sr=8-1
  • Reply
    Roxysteve Feb 23, 2012 @ 11:49 am | delete
    Nice and informative, and one for my maintenance manual, but I just came across another reason for this that if not addressed morphs into helicopter-racing-across-room-and smashing-into-stuff syndrome - a cracked pin in the upper rotor hub assembly.

    Briefly, this allows the rotor to move slightly so that the angle between it and the gyro bar decreases. Eventually the second pin cracks and the rotor can now float in three dimensions, leading to sudden onset uncontrolled-flight-into-face-itis. The good part is that you can actually get the helicopter into the air before the new behavior makes itself known, which ups the excitement factor no end. It's all fun and games until your whirlybird goes for your nose.

    The only cure is to replace the hub and to vow to quickly power off in a crash from now on to minimize the chances of doing the same damage again.

    If you have a Syma 107 that suddenly develops this behavior after a crash and the gryo seems to move freely, suspect a cracked pivot in the upper hub. If the rotor head can be advanced toward the gyro angle then you may have this kind of damage.

    Unfortunately, the only way to be sure is to remove the upper rotors and examine the pivot-bearing with a small probe.

    Additionally, the replacement part set linked to in the article does not include the hub assembly. You'll probably need to buy the entire shaft and either replace the one you have or dismount the hub from it as a replacement for your broken one.

    http://www.amazon.com/Syma-S107g-13-Helicopter-Replacement-Part/dp/B004N37Y8Q/ref=sr_1_1?ie=UTF8&qid=1330015708&sr=8-1
  • Reply
    GrammaLinda Jan 9, 2012 @ 3:42 pm | delete
    I had never heard of the toilet bowl effect with helicopters. Your title pulled me in and now I know something I never expected to learn. Thanks! Blessed!
  • Reply
    TheSummerStore Dec 11, 2011 @ 1:11 pm | delete
    Hey - you learn something new every day, and today I learned about the Toilet Bowl Effect as experienced by helicopters.... the Syma S107 Helicopter looks like a lot of fun. My son loves remote control helicopters.
  • Reply
    Tipi Dec 10, 2011 @ 9:32 pm | delete
    How cool to learn about minimizing TBE while learning about the Syma S107 helicopter, well explained for those of us who know nothing about taking flight....
  • Reply
    dotpattern Dec 10, 2011 @ 7:35 am | delete
    Sounds like cavitation in the air. Interesting.
  • Reply
    StephenC Dec 7, 2011 @ 2:06 pm | delete
    The toilet bowl effect. Dontcha hate that when that happens? Interesting lens and I enjoyed it!
  • Reply
    darciefrench Dec 5, 2011 @ 9:57 pm | delete
    What a neat lens - now I know about the toilet bowl effect in helicopter flight :)
  • Reply
    goo2eyes Nov 30, 2011 @ 3:10 pm | delete
    this is cool. i saw how this helicopter soared upwards.
  • Reply
    DominicWoodfield Dec 1, 2011 @ 12:16 pm | delete
    theyre good fun (and quite hardy compared to other models)! would make great xmas presents, its one of those toys even a kid can pick up in a matter of minutes. some of the expensive models arnt as forgiving as this one, and tend to break the first major crash, but i have crashed this numerous times and it still flies as well as ever!
  • Reply
    DominicWoodfield Nov 20, 2011 @ 10:51 am | delete
    thanks for reading :)
  • Reply
    nbhumble Nov 17, 2011 @ 2:58 pm | delete
    I have never experienced TBE in co-axial helis as i haven't used them much but when i had a Blade mSR, which utilizes a 45 degree flybar (or balance bar as you call it) a similar problem was common. The fly/balance bar here is below the main rotors instead of above and at a 45 degree angle to the main blades rather than at right angles. The diagnosis was the same, binding on the flybar. For more info on rc helicopters of all sizes and types, beginner to expert you are welcome to visit http://www.rchelisandcars.com or http://www.rchelicopterworld.blogspt.com
  • Reply
    sukkran Nov 15, 2011 @ 8:47 am | delete
    informative lens on rc helicopter usage.
  • Reply
    blackspanielgallery Nov 10, 2011 @ 3:48 pm | delete
    nice lens
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