General intro?

N

Nitropropane

Member
hi im new and i need help

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So I just got this helicopter for Christmas and building it was very fun. So far the hobby is going good, but since im a total noob i have a few questions.Tony's build videos helped me a lot but i still need some help.Is there any trick to get 90 degrees for the servos horns on the servos?I tried my best with the sub trim but im skeptical and i would like to get it as close as possible.Secondly after trying to level out my swash as much as i could, i checked the collective pitch.On the low end it was about -22 degrees and the high end about 17 or 18. I figured i was way off and i had already adjusted the collective arms(if that's what you call them) and so i decided to mess with the swash mix.i brought it down to about 45% on everything from the original value of 60%.By the way im using an A9 system.My question is, is it ok to use the swash mix to adjust the collective or should i leave it untouched.I'm also concerned with my tail rod.I had to adjust the travel limits so the servo wouldn't over push and bend the rod or over pull and eventually stress the arm for the rudder so much it would break.My final values for the rudder was left 55% and right 85%. My last and final question isn't about the heli itself but how you start it. My tx and probably everyone elses requires them to lower the left stick(mode 2) when powering on the tx.If that is so, wouldn't it immediately go negative pitch and start spooling up after it loads or do u assign a switch to start the spool up?I thank everyone in advance and keep in mind im new so please don't yell at me if i said or did something utterly wrong.
 
Tony

Tony

Staff member
Moved this to the correct section. we dont' allow any questions in the new member introduction area to help keep the information in the correct part of the forum. this helps future members when they do searches.

I wish I had more time, but i"m sure you saw that your reply was double posted. I'm currently working on moving the forum to a new server so I'm quite busy. But I will try to help as much as I can.

First and foremost, what helicopter do you have? I'm guessing when you say "I'm using an A9", you mean you are using an Aurora 9 transmitter?

Let us know on those and we will do our best to help out. In the beginner help section, there is an excellent write up from the member "Stokke" about how to set proper collective pitch with a flybarless head. If you have a flybar, just make sure the flybar is level and you can again follow those settings.
 
zenmetsu

zenmetsu

Member
The servos don't need to be exactly 90 degrees, just close. If you have a servo horn with arms on both sides, 180 degrees apart, try flipping the horn 180 degrees. Most of the main hubs on the servos have an odd number of teeth, so flipping might get you closer to 90 degrees before resorting to adjusting the sub trim on the transmitter.

What you want to do regarding the swash is get it so that the blade pitch is close to zero when you are mid-stick on the collective and your transmitter is set to 50% at that point. If your pitch at mid-stick is negative, you will need to lengthen all 3 of your linkages between the servos and the swash. If your pitch is positive, shorten all three linkages. Just make sure to keep the swash plate level.

Once the swash is at zero at mid stick, you should find that the full positive and negative angles are similar. You stated -22 and +18, so this tells me that your swash may be too low and mid stick might be a few degrees negative. Once things are evened out, you use the "pitch" cyclic mix to lower or raise the cyclic range until your full positive and full negative pitch angles match the recommended values for your helicopter. For T-Rex helis and clones, you usually want +/- 12 degrees pitch. For other models, this may be different, but 18 and up seems a bit extreme as most airfoils will stall at these angles.

It sounds like you already adjusted the swash mix, so you might be fine, and yes, that is the way to do it.

Regarding the tail rod, try moving the servo ball inwards on the armature if possible. This is usually the ideal fix since the servo will have finer control over tail pitch. Most models have a recommended spacing, and sometimes drilling a hole further in can make things work better. It is normal to limit travel, at both the transmitter and the gyro so as to prevent binding. Usually what is recommended is to move the servo ball in as far as you can while still having full range of motion (from stop to stop) on the tail pitch slider, and then start fine-tuning with travel adjustment.

Most transmitters have two flight modes, controlled with a switch. The "normal" mode will usually be programmed with a linear throttle curve, going from zero at low stick to 100 percent at high stick. This is the mode that you want to use as a beginner. You will program a flat pitch, or slightly negative by 2-3 degrees from low to mid stick, and then increase linearly to 100% positive pitch at high stick. In this configuration, zero stick will not have any motor power and the blades will be slightly negative to help keep the heli on the ground while starting it up. It is normal for the collective to get up to 75% before you take off, so don't think that it is excessive if you have to move the stick that far to get the helicopter light on the skids.

The second flight mode is often called "stunt" or "idle up". In this situation, you have a linear curve for pitch so that you do have full negative at low stick and full positive at high stick. You also have full throttle or near full throttle for all stick positions. You never power up the helicopter with the transmitter in this mode because, as you stated, the motor will end up going full speed unless your ESC has a safety arming procedure. The standard process is to start in normal mode, get the helicopter into a hover, THEN switch to idle-up. But as a beginner, you should not be using this flight mode as it is reserved for inverted and 3D flight.

Some speed controllers have an arming process. Some require half-stick at power up, and then they arm themselves once they see a low stick condition. This prevents accidents from situations like starting in "idle-up" mode, or leaving the stick at a non-zero throttle position when powering up the helicopter. Each speed controller is different, hopefully you have documentation.

The more information that we have about your setup, the better we can help.
 
N

Nitropropane

Member
Ok. The heli i have is a Trex 450 Pro v2.A9 does = the Hitec Aurora 9.For the Trex im just using the stock super combo stuff.So if I understand you correct all tx have a normal mode where low stick has no throttle.I should then program p-curve to be slightly negative until I reach mid stick at which point it should begin to hover.Then I flick a switch so that mid stick is zero and throttle stays the same?
 
Tony

Tony

Staff member
When I set my heli's up, normal and idle up are both 0º pitch at mid stick. It's just the way I have always set them up. Normal mode to start should be T-curve linear (0 25 50 75 100) and P-curve 45 47.5 50 75 100. If you are 0º at mid stick, this will give you about -2º at low stick. Idle up should be a linear pitch curve and a flat or almost flat T-curve. Something like 100 100 85 100 100.

I wish I knew that Tx better so that I could help you out on programing it. but I know nothing about it other than a member that is not on here anymore had one. But I will help out as much as I can.
 
N

Nitropropane

Member
I was gonna originally gonna get a dx8 and i know you couldve helped me but I heard that the dx8s had some problems and the last thing i wanted was my heli to pummeling to the earth.Of course spektrum probably resolved it but on ebay the A9 is way cheaper.Ok im gonna follow sttoke's guide first as that is very step by step and very clear.Once ive done that im gonna need help with all this programming stuff because about the only thing i get is sub trimming and travel limits.
 
Tony

Tony

Staff member
There was a recall on the DX8's when they first come out, but all of that has been resolved. But the A9 is a great Tx so no worries there. Just let us know if you get stuck and we will help out all we can. I should be on here all night playing with the new server.
 
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