Tail Pitch

[Buman]

Hi everyone!

http://www.raptortechnique.com/tailpitch.htm says:

a) "A common confusion about the tail pitch is that the blades should be straight when the stick is in the center. Instead they need a small angle"

b) "The best position to start with for tail centering is to adjust the rudder link so that you have 4.5mm between the pitch slider and the tail rotor casing with the collective stick centered up/down and left/right."

==> Magazines seem to say that the angle should be 5 to 6 degrees BUT my Raptor 50 V2 MANUAL says 15 degrees... so here I am confused about what angle it should be. If you have a Raptor 50 V2 could you please help?

Thanks a lot!

Buman.

[tdswan]

This setting will get you close, but the only real way to know how to set the tail up is to hover it. A quick side note, make sure your gyro is in rate mode when you check the center because it doesn't center in HH mode. Mechanical center and true center are two different things. True center is what you're looking for: i.e. the center point where the tail pitch will counter the main rotor torque in a hover with no input from the gyro. THIS IS PARAMOUNT: Make sure your servo horn is at 90 deg by hooking it to a centered channel on your receiver without the gyro in line FIRST (as you should do with all the servos in the setup).

Once you've got the heli built and are going to hover it for the first time, you need to put the gyro in rate mode and lift off. Pay attention to which way the tail of the heli will drift. If there is no drift, do a little celebratory dance because you got lucky! If it drifts left or right, you need to make the corresponding change to your tail linkage rod to change the length so it will hover true. Once you've attained this, switch it back to HH mode and forget about it. Raptor technique is right, but it's sometimes hard for a newbie to understand why it's telling you to do what it does.

I hope this helps!
Good luck!

[Buman]

Thank you very much TDSWAN but as this is really the Beginner Question field allow me to wonder about a couple of things:

You are saying :

"This setting will get you close"
-> Which setting in the first place, 5 degrees (magazines) or 15 degrees (Raptor manual) ??

"but the only real way to know how to set the tail up is to hover it"
-> Although being a beginner that makes sense to me and a agree with you BUT I just wanted to have a starting point (5 or 15 degrees)

" A quick side note, make sure your gyro is in rate mode when you check the center because it doesn't center in HH mode."
-> Please forgive me but what is RATE MODE and what is HH MODE ?? (I have a JR 500 gyro)


"Mechanical center and true center are two different things. True center is what you're looking for: i.e. the center point where the tail pitch will counter the main rotor torque in a hover with no input from the gyro."
-> I understand


"THIS IS PARAMOUNT: Make sure your servo horn is at 90 deg by hooking it to a centered channel on your receiver without the gyro in line FIRST (as you should do with all the servos in the setup)."
-> And here you got me all confused :) Maybe I am asking to much for more details and explanation about this process ?


Thank you again for your patience dealing with true beginners tdswan - who have the respect to do things right and seeking knowledge from people like you !

Buman.

[tdswan]

#1) I'd say 5 degrees is close, but don't bother putting a pitch gauge on it to fild out. just put the trailing edge a few degrees right to start with. The attached pictures will better illustrate the true center of my Raptor (002) and my Predator (001). Notice the Raptor 50 needs less of an angle because it's a smaller machine and doesn't have to counter the big blades of the Predator, which is a 90-size machine.

#2) Rate mode is when the gyro really only acts as a tail dampener. If a stiff crosswind comes along, the heli will weathervane nose into the wind. In HH mode, the gyro will fight to keep the nose facing the direction it is facing by using all of the tail travel if necessary. You can tell when a G500T is in rate or HH mode (or any other gyro without a light indicator) by when you push the rudder stick, if it's in Rate mode it will always return to center. If it's in HH mode, it will move, but will only return part of the way back because it hasn't sensed any turning, so it assumes the tail input is correct. On a JR G500T (which is what I run on the Raptor) you will probably have the single wire from it attached to the gear channel on your radio(bear with me). If it's an Optic 6, the radio will still call it the gyro channel on your menus, the JR & Futaba will still call it gear. It is probably controlled by a switch on your radio. While in your menus on the radio, get to the end point adjustment menu and find where you can adjust the gyro channel (gear). As you flip the switch, you will notice your curser go from the positive to negative value on your menu. When the switch is on a positive value, it is in HH mode, when you are in a negative value (switch position) it is in rate mode. To adjust the gyro gain or sensitivity, you adjust the positive and negative values up or down depending on how the gyro is performing when it's running. Whew :eek:

#3) Cool, that's a tough one to understand for some.

#4) This one does pass a few by until they get done with their setups and bring it to me to check out. While your'e installing your electronics, it's a good idea to have your receiver and radio on hand when you're installing servos once you're ready to install the servo horns. For each servo, I like to plug it into my rudder channel (because it is the easiest to tell when it's centered) while I'm installing the horns. That way you can try different horns and horn positions to get the servo 90 degrees to the linkage it's controlling for a nice, linear movement through the full travel of the servo. Once you've got the rudder servo horn on at 90 degrees, you can then plug the gyro into the rudder channel and the gain channel and all should be well there. Then the only battle is getting the linkage and true center right on the tail rotor.

I hope that better explains it, it's sometimes hard to tell how much of this stuff is greek to people once it's second nature. In time, it will be for you as well. Good luck!

As you probably can tell, I enjoy helping new people get into this hobby. I almost wish I could do this for a living. Just travel all over the country to help people with this. That would be heaven! I almost enjoy building them more than flying them....Nawwww! :p

[Buman]

"As you probably can tell, I enjoy helping new people get into this hobby."


=> This is so true tdswan... I cannot thank you enough for the detailed explanations: I understood everything you explained (in the language I could finally undertsand!!!) and applied it in my set up... SOOOO TODAY was my very first time starting the engine and it worked beautifully !!!!!!! I have the training gear though as I have grass on my property and sometimes the soil isn't level (I used ties, no rubber band to hold those in place). And I went 1 cm above the gound!!!! The effect and joy was unbelievable :) The helicopter wasn't shaking, the tail didn't go crazy, all it did is slowly drift to the left but I think that is normal (ground effect, correct, tdswan????) I got so exicted for my first try that I sat the helicopter down (I was very nervous!).

The only bad think afterwards is that the electric starter I got died on me: I mean, tdswan, have you ever seen an electric starter not rotating in the outside anymore (the shaft going to the heli) but INSIDE !!!! (where the electric motor is)....?????? It become very hot and that was it... nothing wrong with the helicopter device... so now with memorial day I am not sure I will find a store open :)

Anyway thank you ** so much ** for your help and I am sure I will be asking more as I am getting used to flying. And I certain our conversation will help beginners as well!

Buman.

[tdswan]

The nut that holds the cup on the starter came loose. Just take the rubber out of the starter coupler and tighten that baby down. I had the same problem with mine once.

If the tail slowly drifted left (nose right) it seems you have a slight bit too much pitch on the tail (assuming you were in rate mode). It's probably close enough, but why not be perfect on a new bird? Try turning one of the links on the tail linkage out a turn or two, re-install it and lift off again. The ground effect shouldn't affect the tail too much, ground effect usually makes the cyclic (L-R, Front-back) unstable. Not so much the tail.

If you were in HH mode and it drifted, you've got to turn up the gain a bit and re-try. It's best to get it tuned perfect in rate mode first, though. Once it's set up, you shouldn't need rate mode again unless something changes in the tail.
Setup is sooo critical on a heli. looks like you're almost there!

Good to hear you're off the ground!

[Buman]

"The nut that holds the cup on the starter came loose. Just take the rubber out of the starter coupler and tighten that baby down. I had the same problem with mine once."

=> Hmmm.... it is a Hobbico Torquemaster 180 (a used one)... there is no rubber... two long scews at the "back".... I opened it but not much to see beside the electric motor... the round cover is where the big round magnet is... The fact is when I was holding the shaft with my hand it would 'rotate inside' the cover (no more strenght and power!!!)

If the tail slowly drifted left (nose right) it seems you have a slight bit too much pitch on the tail (assuming you were in rate mode).

=> tdswan, no, the ENTIRE helicopter drifted to the left, not the tail itself (ps: I was in HH mode). Let me know exactly what to do in this case if it happens to be a wrong set up; (for some reason I had read somewhere that is was ok and the helico would behave ok a few feet above the ground - but as I said I didn't go above 1 cm above the ground due to my being so nervous for the first time and couldn't try again because of the starter!).


Thank you again!!!

Buman.

[tdswan]

Ahhh I was assuming you had a starter like mine....won't be able to help you with that.

Yes, ground effect will make the heli favor the left. There I go again over-analyzing stuff! :o If it still pulls one way or another once you get out of ground effect, a couple of clicks of trim will tame it down.

[Buman]

Tdswan, RC stores were open in VA today :) :) so I got.... a brand new Hangar 9 electric starter and one of the high quality shaft extenders (did I tell you that when my used electric starter died I tried to connect the shaft to an electric drill?...well... big no no for me...even at very low power it cut the tip (hex) of the shaft!!! BUT I read that JR shafts are not good quality...). That shaft I got cost me $39 but man you can feel the quality - and I am enjoying the Hangar 9 very much as well... very smoth...very powerful... thank you for the recommendations concerning the Hangar 9! I fired up the engine again today and did another 1 cm hovering :) Slowly but surely, learning all the controls.

Concerning trimming I would have a big question about that: they say NOT to trim the tail (rudder) because of the gyro... what's your opinion about that???

Nice to have here tdswan!

Buman.

[tdswan]

That is correct, with a HH gyro, you should not require trim to keep it centered. There are rare occurences where you do, but not too often. My gyro, after switching radios needed a little trim for some reason. Possibly a different center position from one radio to another, bit it should memorize that each time it starts. Who knows....

The Hangar 9 starter is a pretty good one. It's been with me since I was flying fixed wing and there have been times I abused it a little but it keeps on going. I also tried a drill once to start a plane....That was futile. It just didn't have the speed. Never tried a heli with a drill. A good high-speed one might do it.

Good luck!

Troy

[Buman]

Tdswan, here are a couple more questions I would have. Like you I OVER ANALYZE things so PLEASE forgive me if my questions are stupid.

A) I flew the helicopter again and this time more than one centimeter above the ground! And this time I did notice that the tail was 1) Going to the left 2) the noise was pointing to the right.

-> I turned the [left] stick just a little to the RIGHT (rudder right) and that corrected the behaviour but I had to maintain the "pression" on the rudder that way.

So my question is (about the mechanism): when you rudder right, the rod and servo should move towards the back of the heli and when you rudder left , the rod and the servo should move to the front, correct?

B) Do you know or have you used the JR 8301 transmitter ? I have such transmitter with the JR 500 GT gyro. There is a setting in the menu of the JR 8301 where you can access the gyro settings... but I must say that despite the manual I am totally lost on what to do with such settings. They show INH, AUTO and some manuel settings...

-> What would you do about these settings ? I mean what the proper way to set up a gyro using this panel of settings. I know... I am asking a lot...!

-> Going back to Rate Mode and HH. I did find the "gear setting"...right now, on the display of the transmitter the "little dot/bar is to the left : that means positive (HH) correct? When I switch the gear SWITCH, the little dot/bar moves to the right: negative - rate mode, correct ?

C) As I don't really know what I was doing setting up the JR 8301 (GYRO settings) I noticed that sometimes when I rudder right or left (at home without the engine running) the servo will move, then after a couple of seconds, it goes back exactly in the middle. When I used an other setting (it maybe AUTO, I am not sure anymore!) the servo will automatically move back and forth (* NO * delays in second this time) when I manually, with my hands, displace the tail left or right in order to simulate drifting, but it doesn't go back exactly in the middle.

D) That rudder servo always has an electric sound attached to it (buzzing????) - Is that normal?

That is all! Hopefully you understood everything I wanted to ask or I am concerned about :)

Thank again for so much patience!

Buman.

[tdswan]

If you're pushing right to keep the nose from going right, your rudder channel is backwards. A good way to remember what way the rudder should go is the direction you push your rudder stick will make the FARTHEST part of the heli that direction. I.E. if you're tail-in and you push the stick right, the nose of the heli should go to the right and vice-versa. This is an easy one for a newbie to get reversed. Reversing your rudder channel WILL NOT reverse the gyro, so don't worry about flipping the reversing switch on that as long as it's working correctly.

I am using an 8103 transmitter. I was using a 6102 to start with and recently bought the 8103. I'm not saying you are having the same problem, but when I programmed the 8103 for the Raptor, I had to put some sub-trim on the rudder channel for some strange reason. You shouldn't have to do this, but I haven't had to adjust it since, so I'm not extremely worried about it. What the tail would do is slowly creep when it sat there not running and also would creep in the air. It's POSSIBLE you are experiencing the same problem, so I wouldn't rule out putting a little trim on the rudder.

On the gyro sens on the 8103, just make sure it's all on inh for now. You won't need these features for some time. What it does is allows you to set 3 different gyro gain settings for the different flight modes on the radio.

OK...the MONIT screen, I'm assuming that's what you're looking at for the dot to go from one side to the other. What you first need to do is make sure the single wire connector from your gyro is plugged into the gear on your receiver for this to work, not trying to insult your intelligence, but I've gotta be sure. Then you need to go to the [TRVL ADJ] screen and if you don't see gear anywhere, hit the select key to bring up the other 4 channels. Gear should now be in the top right. This is where you adjust the gain on the gyro. Yes, a positive (1-150%) will give you a HH mode and -1-150% will give you rate mode. Flipping the gear switch will allow you to toggle between the two settings. Start around 75% on both (-75% on the other) and test the gyro in a hover. If it drifts in HH you need to possibly raise your gain OR trim like I did on mine (although in a perfect world, you shouldn't have to). Once it's holding, play with the gain, raise it up 10 points and hover it again to see how it's holding. Is the tail shaking violently? Then back the gain down again. If not, try raising it. The goal is to get the tail gain as high as you can in HH mode without the tail wagging. (although like stated before, you should set the tail up in rate mode first)

Again, on point C....make sure any advanced gyro features are disabled (inh) for now along with the invert switch (that could make things ugly :eek: ).

Yes, the tail servo will make some noise even when it's not doing anything. This is normal. The gyro makes it do this.

There's no stupid questions! You're not the only one out there with these type of questions and it's good that there's forums out here like this so people can see they're not alone.
Good luck!

[Buman]

Tdsawn, thanks a lot for your answer. I spent a lot of time checking everything and yes, you were right, the rudder was inversed and I also noticed that the moving forward/moving backward was also inversed (shame on me).

I did find the command for the GEAR/RUDDER/GYRO but nothing happens (beside switching to - or +) when I switch the switch on the JR 8301. (What you first need to do is make sure the single wire connector from your gyro is plugged into the gear on your receiver for this to work ==> yes it is as I am able to switch from negative to positive).
So what it does is, when with my hand I move the tail left or right, the tail blades change accordingly (I checked Raptor Technique on the web and his step by step and everything is moving the way it is supposed to move with the Gyro). And yes it returns EXACTLY in the middle/90 degree angle with the rod. BUT with all that, during my last fly 15 minutes ago, when I run the engine higher and higher, the ENTIRE tail vibrates/shakes, it shakes/moves left and right, no too much distance (you know what I mean) but at a VERY high pace and therefore when I try to lift it a little bit I have the feeling that the helicopter is going to tip over...and I am sure it will.


I am sooooooooo frustrated... I never said "yeah I know everything"... I am following any advice and settings but my results are terrible.

And I really don't know what to do next....

PS: This are the features of the helicopter if you think about anything...

Raptor V50 V2 with OS 50 and Gyro JR 500GT and transmitter JR 8301 (all servos are JR ) - Blades are Maverick ones.

Buman.

[tdswan]

Tail shake, I assume you mean a tail wag. Shaking violently L-R until you land it again. That is when you should lower your gain on the gyro (lower the positive number on the gear channel. Lower it by 20 points or so and re-check it. Like stated previously, you'll have to play with the gain until it behaves by not wagging. Adjust it, then test, adjust, then test.

Also make sure your headspeed isn't too fast (throttle set too high at hover). Mine will hover just beautifully even at max gain but wil wag when it really gets moving in idle up (higher headspeed). If you've got the means to check your headspeed with a tach, for beginner hovering, you should only be in the neighborhood of 1600 RPM. If you don't have a tack, don't sweat it. Just make sre it doesn't sound like it's going to fly apart.

[Buman]

Ok, thank you again tdswan, I will try all that - yes it does shake left and right but not when flying: it does it when I am on the ground - a) I fire up the engine b) start putting gas and then it happens c) That is why I try to fly above 1 centimer above the ground it seems that is going to tip over.

Buman.

[tdswan]

The gyro doesn't become effective until the heli is in the air. The shaking on the ground could be a poorly tuend engine, but let's take one thing at a time :D

[Buman]

The gyro doesn't become effective until the heli is in the air. The shaking on the ground could be a poorly tuend engine, but let's take one thing at a time :D


In fact, not being able to do ** anything ** because of that violent shaking up and down and right to left, when I read your sentence "The shaking on the ground could be a poorly tuend engine" I decided to work on that because again I think it should be the very first thing one should take care of otherwise as I said you can't go anywhere, you cannot do further settings (my humble but I think realistic opinion). So I did tune the engine and you were right it is now much, much better. But after a second tank of fuel, as I increased the engine, I heard a "pop" and the engine stopped suddenly. I stopped the blades with my hand and saw some smoke coming out of the glow plug extender and the glow plug. I left it that way so that I can ask you what happened here......... (more frustration as you can see :( ). What should I do / check / replace ? And above all what did I do that lead to that "pop" and the engine stopping with smoke coming out of the glow plug ???

Thank you again.................

Buman.

[tdswan]

Without seeing the engine, I cannot diagnose that. It's possible the glow plug came loose and vibrated out of the engine. It could be that minor or something much more serious. If it was running too lean, and I mean WAY lean, you could have done serious damage. Take the canopy off and see what kind of shape the glow plug is in. If it has come out, screw it back in and make sure it's snug, but you don't have to reef it in. If you can see into the glow plug hole with a flashlight or something, see if the piston looks OK. Even possibly taking the muffler off to check into the exhaust port. If all looks good, see if it starts. If it runs OK, you've got no worries. :)

I don't know where you live, but I'd start searching for a local pilot and/or club. A lot of these questions are getting pretty tough to answer without seeing how it behaves. I may have been inadvertently misleading you without seeing how the heli runs and how you've set it up. I can only assume everything else is set up correctly, but it's looking like it's not quite perfect yet. I'm more than willing to help, but there's some things you just need to see to diagnose. You have been very descriptive and this helps. Don't worry, you're not the first guy to have these questions and you're not the first guy to have problems. Hang in there! :cool:

[chaos]

When I first messed with helis my gang didn't have gyros. I learned without one, and I kinda still like to "go raw". There is the right way to do a thing, of course, and then there's my way. I set the tail to "somewhere". Then, without the gyro, I try to hover. I mess with the trim till I get a straight hover. Then I shut down and mark the place where the tail pitch needs to be, and center up the rest of the stuff to go along with that, without the trim.

[Rotor Ruiner]

The three best things in life are a good landing, a good orgasm, and a good bowel movement. The autorotation is one of the few opportunities in life where you get to experience all three at the same time.

I could not agree more, LOL