I know it's there to counter out the torque for the main blades, but how. Does the tail need to have some pitch to keep the heli straight? I'm asking cause I took everything apart to change the gears, and don't remember how it was. If there wasn no pitch there would be no lateral thrust generated, just centrifugal force. Is that what keeps the heli straight? Or is it the thrust from the pitched blades. I have the Walkera 22d and it spins very easily. I have not been able to Hoover at all. It won't stay straight. Can I replace the gyro with a head holding one? Can that be done? I have no idea how to adjust the gyro. I just realized it's possible. I've had this thing for 3 months with plenty of down time, and still no control. What type of cable to I need to hook my Transmitter to the computer to try a simulator? Thanks Alot. I'm learning slowly but surely.

you need a few degrees of right tail to hold it from the torque of the blades. if your unable to hold it with an input from the transmitter in the opposite direction of the way it's spinning then you either have the servo or the gyro reversed. a reversed gyro makes the tail spin uncontrollably, test it by holding the heli and yawing the tail in one direction and watch which way the servo moves, if you spin the heli to the right, the gyro should make the servo add left tail. you can get a HH gyro and replace the one you have but if the one you have works I'd recommend using it. if you just want a HH anyways, the Futaba GY-401 is hard to beat at the price.

kc

let's put it this way, THEORETICALLY:

At a CONSTANT mainblade rpm you also have a constant & proportional tail rpm

with the above assumption, you have a constant force on the frame of the heli going in the opposite direction [counter clockwise] of mainblade rotation (action reaction)

to neutralize this CCW force, the tail rotor needs to exert a constant force clockwise

therefore, you need a constant tail blade pitch AKA SUBTRIM on the rudder to make the tail push CW.

in reality the forces are not constant due to motor loading, friction, and battery depletion.

the rate gyro should only slow yaw movements that are too quick. the tail WILL still drift slowly and the gyro will not correct this unless you have a HH gyro.

rate gyro - gives a stab of correction (to slow) and returns to neutral position (will drift, you are supposed to do the rest). this is why neutral position MUST be dialed in.

in other words, you must find and adjust the neutral and constant force of the tail...neutral for HOVER + full battery. during spool up it will be slightly deficient and during climb it will exceed. this is where REVO mix comes into play.

as the battery dies, the total RPM will decrease and the tail force will be deficient. This is what makes E heli harder (with rate gyro) than nitro since they dont lose rpm as they use up fuel. you will need to trim rudder as your battery level dies and then reset when you put in a new one.

Most tail rotor assemblies have a hover OFFSET (pitch) built into the blade grip to slider linkage ... so with the t/r rotor input at neutral and trim and subtrim centered, you will be producing the necessary pitch to hover (assuming you've set your heli up to match this built in pitch).

Of course, this hover OFFSET will only work at hover. The moment you change this (collective pitch change, RPM change, etc), the main rotor to fuse torque differential will change and then the hover OFFSET will not be sufficient ... the heli will YAW.

Some "system" must be in place to control the YAW ... assuming the pilot doesn't want the heli to go spinning roundy roundy.

The first very basic system is the pilot him/herself. Just move the t/r stick to correct for the YAW change. Ok, it may not be the best system but it's certainly do able.

The second is you can program some REVO to "kinda" correct for the change. REVO is just a mix that adds a little (or alot depending on your programming) t/r adjustment based on where the t/r stick is. So it adds the necessary t/r movement as you move away from hover (either up or down). The only problem is that it's a mix in the TX and has no clue what the forces are actually at the heli. A YAW control system onboard the heli would be better ...

The third is the gyro itself. In Heading Hold, the gyro itself would hold the YAW on the heli so you as a pilot can move the collective stick all around and not worry that there are torque changes ... the gyro will deal with it and while in Heading Hold will control the YAW.

Good Luck,
d.tipton

It's just an old fashioned thought but have you thought about the old tried and tested remedy known as RTFM?

Thanks for the feedback. archie, RTFM hmmm Whats does that mean? haha.

OK I understand the how the tail rotor works now. I'm going to do a search for REVO Mixing Programing. I have no idea what that is. Tippy, I don't think my heli has an hover offset mode. I dont know if the gyro is working properly or what.
KC, I'll try that test tonight but I think I've done that before, the servo doesn't do anything. AHHG...My heli came with a terrible instruction manual. YAW is to spin the tail of the heli in one direction? How can I find out how to adjust my gyro and get it they way it should be? I'm not giving up. Thanks, Greg.

Hover offset is not a mode ... it's just how the tail rotor is built. Basically, if the t/r slider is center in it's range of motion ... the linkage to the blade grips produce a tail rotor pitch offset. So all things being centered (stick, trim, subtrim, servo, slider), the "built in" offset between the slider and blade grips will produce hover pitch on the tail rotor.
This hover offset is always there.

If you have an electric motor on the tail rotor then the speed of the motor will change your t/r thrust, but the principle is the same ... generate an equal and opposite thrust to counter whatever your torque value is.

When you move the stick/servo/motor controller (or the gyro moves the servo/motor conmtroller), the resultant pitch/RPM change is always the input + hover offset/hover RPM.

Actually YAW is in either direction, however, YAW produced by torque will be in one direction ... opposite the direction of the main rotor rotation. So a right rotating main rotor will generate a left nose YAW. The hover offset is designed to produce an equal and opposite force (right nose YAW). If everything balances out, you will hold the nose with no YAWing.

Good Luck,
d.tipton

Thanks. Just to make sure were on the same page, what is t/r, trim, and subtrim? Will I know when I have the hover offset right when I can take the heli off the ground and it does not yaw at center stick? If it does yaw do I adjust the trim? If its way off do I take off the linkage from the servo and adjust that accordingly. I was thinking the trim was those tabs that slide side to side or up and down. They make a clicking noise when you slide them. On my transmitter the right stick always goes to center. It feel like its spring loaded to return to center when I release. The throttle is the only one that stays where I put it. Also how to you go about adjusting your gyro?
Greg.

t/r - tail rotor

trim is using the trim pot near the actual tx stick (electronic or analog) usually for temporary corrections during flight.

subtrim is using the menus (electronic) in your Tx, to accomplish the same thing.

during take off it SHOULD and will yaw PREDICTABLY - if the subtrim point is set correctly in hover, then during take off you will have a deficient amount of power (assuming a typical normal mode curve) therefore you will have to manually push the rudder right a little bit due to the t/r rpm being lower than in hover.

now once you are in a stable hover, that's where it shouldnt yaw faster than you cant control. (rate gyro might still yaw slowly = drift, but nothing crazier than what can be corrected manually). this is called 'flying the tail'. it needs constant input and correction.

now as the battery dies, the rpm will decrease in the whole heli. that means the heli will progressively start to yaw left. to correct this you might use trim while flying until it stops or youll just have to hold the rudder stick right while flying. your battery will probably be dead by the time you max out trim, either way you should stop by then.

dont even worry about revo mix yet. you wont need that until you start getting more aggressive with the throtle.

basically to find this subtrim point - disconnect the gyro and spool it up without one (dont do this if you suck - youre not supposed to take off lol). add some right rudder manually while spooling it up really really carefully. add subtrim for right rudder until you can get it light on the skids and it is only drifting. do not ever blip the controls while doing this because it will disturb the balance of the heli and without a gyro to compensate it's going to go crazy.

the alternate method, the one i actually use is to spool it up in my hand (versus on the floor) and add subtrim until i can feel the neutrality point in the heli where the tail cancels the motor torq.

revolution mixing is NOT for aggressive throttle/collective movements. it simply compensates for torque applied during smooth transitions from mid stick to full stick and in the opposite direction from mid stick to low stick to compensate for counter torque. back before they had heading hold gyros we turned revo mixing way down in stunt 2 for basic aerobatics and off in stunt 3 and above for aggressive 3D.

kc

OK thanks. I'm going to take a closer look at it tonight. I need some spare parts (another story) before I can try to take of again. One thing, I read in The Electric RC Heli beginners guide that it is very difficult to hover indoors with a rate gyro. Does everybody agree?

the gyro could care less if it's inside or out and doesn't know any differently. the only differences are outside your susceptible to wind, indoors unless you've got fans running there is minimal if any wind influence.

kc

OH. Is that something that needs to be done. How do you do Revolution mixing? I would very much like to know.

if your gyro does not offer HH or you have a HH gyro but have it in norm mode then revo mixing is very useful. on non computer helicopter radios they have pots to adjust the revo mixing, one is called up (works from mid stick to full stick) the other is called down (works from mid stick to low stick). computer radios call it 'revolution mixing' and you can scroll through your radio menu and find it if you don't have an instruction manual. on computer radios people who are not familiar with how revo mixing works will often put in a + value on both up and down, this is incorrect, you want a + for one and a - for the other or your will be adding right (or left) tail input in both directions of stick deflections.always visually check the tail pitch slider for correct deflection in both directions prior to flying.

Up revo mixing adds right t/r as the stick is advanced from mid stick (hover) to full stick as you progress into forward flight or vertical ascent, this prevents the engine/blade torque induced yaw you get as you advance throttle collective.

Down revo mixing adds left t/r as you move the stick from mid stick (hover) to low stick as your descending. this is most often a much lesser value of mixing.

kc

The other trim is the mechanical trim of the heli. With a servo/linkage/slider/variable pitch t/r set up, the relationship between servo postion and t/r pitch is adjusted via linkage length. This is the mechanical trim. The TX trim/subtrim can adjust for only so much mechanical "un" trim. Generally, minor TX trim is OK but if the trim is all the way to one side and you're still having to lean on the stick, you really need to think about getting the mechanical trim set up. You probably need to get the mechanical trim set correctly first before you start touching the TX trim/subtrim.

If the heli trim is electronic (electronic motor or coaxial rotor) then the controller on the heli needs to be adjust (electronically equivalent to mechanical trim) to achieve close to correct trim before touching the TX trim/subtrim.

Good Luck,
d.tipton

Wow I really appreciate all the information. I still have more questions. Should I try to get my revo mixing right before I try to fly again. I can't even hover at all, in fact I seem to have very little control over the thing. I can slide it around on the floor and control it, but the tail is very loose. It always swings out, and I lose orientation and have to stop. I'm really trying to understand what revo mixing is, I understand what it does, but not how to do it. Do I need to adjust my gyro to do it. I looked at it last night and it had two holes for a flat tip screwdriver to turn some knobs. They were labeled, but I forgot. What is a computer radio? When you use the term radio, are you referring to the transmitter that you hold in the hand when flying? I do not have a HH gyro. KC what do you mean by computer radio, and scrolling through the radio menu?
One more thing when I move t/r stick right the tail goes right. How do I fix this? Sorry for all the questions, but I want to fly this thing so bad. haha.
Greg.

Thanks Tippy, I know how to adjust my linkage and trim, or maybe I don't. I kept adjusting the linkage, then spooled it up til it was light on its skids and see what direction it would go. I got it as close as I could them used the TX trim. When I move the t/r stick right the tail goes right. I'll need to fix this first, before going any further.

You are correct about this!
A right t/r stick input should produce a NOSE right/tail left movement. Your description is definitely backwards from the norm. Should require a simple reversing of the t/r (rudder) channel at the TX. And while your "fixing" things, make sure the gyro is in phase also ... ie in rate mode, a heli nose left produces a nose right correction at the tail rotor.

As far as REVO is concerned, if your going to be spending your next dozen flights practicing hovering, then REVO is not required ... as long as your heli and TX trim are good for hovering. It's because you are going to be spending most of your torque generate fairly constant ... REVO adjusts for "theoretical" changes in torque. If/when you decide to use REVO, input small increments at first.

Good Luck,
d.tipton

over the years I've came across several people who fly the tail (right t/r moves tail right) rather then the nose when it comes to t/r input. know a few who are quite good at it, but it makes it very difficult for others who fly the nose to fly their bird. one of the ones i know was the first person i ever seen do a tail in auto (about 10 yrs ago), he couldn't do it forward he was to scared and couldnt nose in but could grease it on tail in, now that is the normal finish to a 3D flight by most people.

kc

I'm still going to change it before I get to used to it. I went to change it last night and holy crap! I have 8 switches on the back of the transmitter. The first 4 were labeled !QUOT!on!QUOT! and the were all up. The other 4 were labeled DIP. I was all powered up and i changed the 4th !QUOT!on!QUOT! to the down position and all hell broke lose. My heli went into FULL throttle. It scared the Sh#T out of me, I was on the coffee table I was on the couch. Luckily I had not taken my finger off the switch and was able to reverse it. It landed on the couch with no damage. To make the nose go left with left t/r input do I mess with those switches? What is the term radio mean? Is it the transmitter?
What does Tx mean? Thanks.
Greg.

one of those first 4 switches most likely controls rudder input so you'll need to flip it. now that you know one is throttle it should be safe to flip the others and see what they reverse.

Radio is the Transmitter which is abbreviated Tx.

kc

Radio ... The wireless transmission of electromagnetic energy through space via radio waves.

Transmitter ... a device that sends/emits (electromagnetic) radio waves ... often shortened in text by writing TX ... in the RC (radio controlled) hobby it is also often called the controller.

Receiver (RX is a short way of writing receiver)... a device that is tuned to receive a specific frequency (or band) of radio waves.

Both are generically called "radios".
While in your car, you listen to a radio (transmitter) station by tuning your radio (receiver) to a specific frequency.

If you don't know what the switches do, I might suggest unplugging the motor from the ESC before trying. You can at least check out swash movement without the heli taking off ... or at least tie down the heli so it can't fly just in case you hit the wrong switch. It would be nice to know the line up of your channels (what they are supposed to control). A Futaba channel assigned has throttle on channel three and rudder via gyro on channel four. Either your TX/RX line up is different than Futaba or you have something plugged up wrong.
Something else to figure out I guess.

Good Luck,
d.tipton

Just so I'm on the same page, is this kinda what you have:



Good Luck,
d.tipton

Yes tippy, thats what I have. What does ESC mean? I will unplug it, because I don't what that to happen again haha. What do those adjustments on the gyro do. I can turn the knobs with a small flat tip screw driver, but I don't know whats its doing. The gyro is working when I yaw it left it gives the t/r right input, When I get it lite on its skids it will spin and I have to do it manually. I'm going to work on the trim some more tonight. Thanks.
Greg.

Electronic speed control (ESC). The typical ESC has three connections: (1) main motor battery, (2) motor, and (3) servo-like lead that plugs into the RX.
You probably have a multi-function receiver ... RX, gyro, ESC, mixer,etc
Can't find a close enough photo to see what the adjustments are for.

Now that I see you have a regular servo/linkage/slider/tail rotor pitch set up ... it might be easier to help along.

Good Luck,
d.tipton