|May 01, 2008, 05:26 AM|
MIA Walkera 4#3 Collective Pitch Sim Tests.
Ok I couln't wait for the Walkera 4#3 Collective pitch so I made one for Real Flight G3.5. The standard model can be downloaded from KE Forum, but the model doesn't fly well, so I considerably enhanced the flight dynamics to get the results that you see in the attached video. It has collective and more powerful engine. If the real 4#3 could be modified for collective and have a real miniature nitro engine, it woudl fly like I am flying the model in the video, perhaps better in the hands of a PRO.
|May 01, 2008, 09:23 AM|
Hey baygenco, I don't know if this will help, but sometimes having the blades to tight or to loose in the grips will cause TBE. I'm sure that you know this, but try snugging up the blades just tight enough that they move in the grips, but not loose enough that they fall when you tip the heli on it's side.
|May 01, 2008, 04:52 PM|
I am sorry I have not been keeping track with every post lately, busy, but can you tell me what you mean by TBE and I'll try to see if I can help you.
|May 01, 2008, 05:03 PM|
Joined Jan 2008
i thought this was a common problem with rc helis happens when there is a failing component in the rotorhead mechanics.
any input will be much appreciated.
|May 01, 2008, 10:29 PM|
Troubleshooting TBE Toilet Bowl Effect - Lack of counter Torque Control
OK thanks for sharing with me the TBE, it sounds to me like lack of counter-torque control.
When there is not enough tail power or none to counter the effect of the main rotor toque with a CW main rotor, the resulting effect will be a helicopter that wants to turn about its main rotor axis, to the left, CCW, while the tail spins oposite direction, to the right, but heli still spins ccw about the rotor axis.
Possible causes for this effect:
Lack of tail motor power
Visually, check to make sure none of the motors have picked up lint,
especially hair, this sometimes is hard to see right away and is a cause for
components like motors, gears binding, thus not allowing proper Rotor RPM.
Is your tail motor working at all? If not inspect that wires, to it, have not
broken in the crash. In fact, inspect that all wiring looks intact and that no
wires have ripped or are touching other parts, especially the main motor at the front end connections.
Check your battery, make sure you have a good battery.
If Battery OK ,check your Tail Motor, if you can, connect a 1.25V AA
battery directly to it by first disconnecting both leads of the motor from the
boom wires, and see if the Tail rotor has Power. Try with new tail motor and see if you have the same results.
If both are good then possible electronic component failure, possibly in the
ESC electronic speed control or gyro section that is not providing enough
power to the tail motor to keep up, in counterbalance, with the main.
Give that a shot First.
Suspect Control Module Failure?
If you have a second Control Module, you can swap with
the one on your heli that you are experiencing trouble with and see if that
resolves the problem.
If you were flying fine before the crash, and then the troubles started, it is possible that your might have ruined your gyro in the control module. The gyro used in the modules are made from "piezo elements" , which are very sensitive resonant crystal devices, just like your Frequency Crystal is on regular FM Receivers, if the crash is hard enough, it is possible to ruin the piezo element beyond repair. But check as per above, first.
if i leave the sticks the heli goes left-backwards-right-forward and looses altitude.doesnt want to go straight forward too.
All helis require constant control input to keep them steady in hover, it is possible that you can dial and balance the heli so that your control imput is minimized and the heli becomes more stable, but if you let go of the sticks the heli is going to eventually wonder no matter how stable it is.
Depending from which point of reference you are looking at the heli, if you are flying tail in, and the helicopter wants to go backwards then the CG is too far back
Heli doesn't want to go forward could be mechanical control or electronic control related. Check the rotor head ball arms and links, make sure these didn't get bent in the crash. The links between the rotor head and flybar need to pivot on the rotor head and flybar balls smoothly for crisp control.
|May 02, 2008, 07:52 AM|
|May 02, 2008, 08:30 AM|
Blade balance or tracking could also cause it. Uneven flybar paddle angles may also have an effect.
I was getting TBE and rebuilt the whole mainshaft and head assembly, checking balance and angles and making sure everything moved freely and without play. It worked fine afterwards, but I am not sure which part was causing the problem.
Good luck with it.
[EDIT]Make sure to check that the flybar holder pivots are secure. I replaced mine with a brass tube. Helps stability a lot.[/EDIT]
P.S. - Mario, TBE is when the heli moves in a circle (with the tail facing the same direction usually), not when it spins due to lack of power in the tail.
[EDIT]Martyn McKinney gave a nice explanation a few posts back.[/EDIT]
|May 02, 2008, 04:19 PM|
Toilet bowl effect, I was thinking of when you flush water down a toilet. it spirals down and it is CW or CCW depending on which part of the earth's hemisphere you are at, at the equinoxial line (center line of the earth, as in the Equatorial line) this effect, called the Coriolis effect, disappears, cancels.
This is pretty cool to see, also some some forces have no effect at the very center of this line. This effect is also due to earth's magnetic and gravitational forces. The coriolis effect is very complex to explain in detail adn via physics, but most people understand it as I have just explained. This, to acertain degree has an effect on any free moving, rotatin object. I was at the equatorial line, in Ecuador, last year and was able to to be part of some interesting experiments by a guide that was explaining and talking about the effect of earths magnetic forces. So this is my understanding of it, I am not a physicist and so this can be further explained by someone who is.
So you are seeing a rather spiral movement while the heli maintains steady heading?
I am still trying to pinpoint this effect you guys are calling it TBE. Is it really spiraling about its main rotor axis while maintaing heading or is it
moving around in circles? with the nose tangential to the circle it is moving about?
Also, if it is spiraling about while maintaing heading , is it really spiraling? or perhaps the body of the helicopter is bobbing (dancing) about the main rotor? Is this what you are seeing? instead?
About the 45 degre angle positioned flybars like on the MIA 4#3 Semi-Auto stabilizer System.
What Martyn is explaining about the helis with 45 degrees flybars (auto stabilizers) you would only see with such helis not with the regular 90 degree flybar 4#3, unless you had one set up like the one I did with what I called semi-auto stabilizer, also with the 45 degree flybar. As this type of stabilizing flybars want to keep the heli in one place ,as the helis wants to wander about, and this is not the flybar, so much as, it is the way in which the flybar is position and connected to the main blades' pitching. Also this type of flybar does not provide forward motion regardless of number of control channels, 2 or 4, but it is the way the helicopter balances about the CG, couple with the reaction of tail countertorque control, that allows the 2 channel helicopters to move forward, or backward respectively to nose heavy or tail heavy.
So the TBE could be due to various reason depending how you interpret TBE and perhaps, I am making this more complex then what it is ,but doesn't hurt to cover all angles of posibilities.
I am still thinking that what Bayeno may be experiencing might be a head bobbing that is throwing the helicopter about, in what may look like a spiral motion TBE, and this could be due to unbalances in the roitor head system, beginning with the flybar paddle distances, actually this would be in a sence vibration and harmonics transfered to the the rest of the helicopter that will make it take its own pattern of movement about its pendulum point (where the head pivots on the heli).
|May 02, 2008, 05:03 PM|
I think what they mean is that the heli starts to sway in a circle, keeping the heading relatively stable. The heli starts to drift in a circular pattern. I have experienced this, and the things that I could identify that needed improvement on my heli were:
1.the paddle pitch (I like mine a 0 degrees)
2.the blade tracking. On one side of the revolution one blade provides more lift swinging toward the nose, and the same blade on the other side doing the same thing, but swinging toward the tail. The heli will have uneven lift at any given moment, causing it not to be as stable, and causing it to drift, then eventually pendulum (or tbe as we so affectionately call it)
3. If the swash is even a little bit out of level, the heli will move , and when the heli moves it will try to right itself ever so slightly causing it to move in the other direction. Like Mario said, the pendulum effect will start. We all remember the pendulum in the sand right. When you swing it, it will slowly work itself into a circle shape rather than a line.
To sum it up, you would want to make sure that your heli is a rock solid and balanced as possible. These effects are present in all helis, but are greatly amplified (as well as regular flight characteristics) in sub micro helis that we all love so much. The only heli that I saw that was stable hands off for any extended period of time was 3VW, check out his hover stability clip on youtube. He did spend A LOT of time balancing everything on his heli to get this to work.
|May 02, 2008, 05:45 PM|
My 4#3 has developed the wagging tail now.I can hear the tail motor pulsing as the tail wags.
Also the tail is going up and down slightly as I hover.
And Iam getting the TBE also now.Mine goes round,but loses height and gains height about 12 inches each time the heli makes a revolution.
The receiver is held tight and if I hold the heli by the skids and power it up there is no vibration.
Iam guessing there is something worn in the mainshaft/head area.
Has anybody else found these symptoms?
|May 02, 2008, 06:20 PM|
ok so I was thinking someone really had a problem with the TBE, reason for my lengthly post.
But Yes absolutely, all helicopters sway from stable hover at some point and in patterns that appears as if the heli is snot supposed to be doing that. I mean the whole thing about flying helicopters is about leaving some control to the pilot so that is doesn't become boring. Or do we really want something that will fly by itself and we want to simply observe it. However, absolutely, depending on the amount of time you spend, on tweaking the control system (removing any play in the mechnical parts), adjusting the CG, countertorque balance, etc., is going to get you closer to a more stable and easier flying helicopter, as on the last video above.
Is typically the results of an oversentive gyro, or vibration in the tail rotor or even main rotor section, going a bit further, if the main motor starts to go this uneven motor operation on the main rotor can influence that pulsating tail wag, as well, because, see.. the gyro's main purpose is to sence tail movement and tell the ESC for tail electrified helis, to speed up the tail rotor to keep up with the main rotor. If there is an uneven operation of main rotor that is transfering this motion into vibration to the tail, the gyro is going to be trying to keep up with it and the result will be tail wag.
Typically Gyros, and even 3 in1 and 4 in 1 have, on the gyro side of the PCB, a potentiometer to adjust the gyro sensitivity, gain. You can play with this setting if you experience tail irregulatities, but do so only after you have checked out that there are no mechanical or dynamic umblances in the rotors and are cetain that the motors are still good.
|May 02, 2008, 06:34 PM|
Joined Apr 2008
newly into this hobby and got a 4#3. Stock at the moment aside from a spring from a pen to hold the swash plate steady. I've not dared adjust anything at the moment, but after looking at that video I can not imagine mine ever being that steady. Mine normally pitches backwards. I've got it to the point its very steady with the tail rotor but hovering like that video is awesome and quite appealing!
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