This is a discussion on RC helicopters + fireworks = fun! within the The Short Bus forums, part of the Specialty Fun Forums category; I got my new batts for my heli!
Tried to fly it yesterday, but it didn't stay powered for very ...
If your your heli VIOLENTLY spins on spool up, and it just seems to go faster and faster....it's not your gyro gain, it's the direction of the gyro. There should be a switch on the gyro labeled "Reverse" or something similar. If not, check the instructions and figure out how to reverse the gyro. It has to be done on the gyro itself, not the radio.
At worst, with REALLY bad gain settings, the heli will drift significantly when stationary and the tail will spin quickly during high power punches. It won't constantly spin, that's a red flag that the gyro is reversed. If your servos (between stock and the metal gears) were reversed, that's why it needs to be reversed now. You can fix the issue by either flipping the tail servo 180* or by reversing the Gyro...either works.
Easy way to check. Power up the heli, make sure that the throttle hold is on, or that the motor is disconnected. Hold the heli in front of you, so your looking at the side (the nose is to your right and the tail is to your left). Rotate the heli by pulling the tail towards you (counter clockwise). The gyro should be making the tail SLIDER slide towards. That is the correct motion. If not, then reversing the gyro should fix it.
Sorry, didnt explain myself well on that. The heli was slowly wagging its tail sitting on the ground. I told it to rotate left and it did but very rapidly. I let the stick go back to center and the heli SHOT back the other direction and cut my foot. The new servos are twice as fast and strong and the gain was just a hair too high for them. I have since corrected it.
Today I am trying to learn how to set up the pitch curve on my radio. It has no instructions and I cant find any online. It wasnt at zero pitch when set in 3-D at half stick. I dont have a pitch gauge so I did the folded blade method. My radio has two knobs marked "PIT" and "PLT". So I put it back in normal mode and unlocked the radio. The best I could do after messing with it for an hour is about -1 to -2* at zero stick, about 5* at mid stick and 10-11* at full stick (in normal mode). "PIT" is obviously pitch but I am not sure what "PLT" is. I think it is like a pitch gain cause it affects how much pitch is given for throttle travel but its linear. The radio does not seem to be programmable to set exactly how much pitch I want for each stage of throttle travel.
But now in 3-d mode its 0* at mid stick and has full travel in both directions with no servo chatter at the maximums now so I guess I am close. I ordered a pitch gauge last night but it will be some time before it comes. I couldnt see spending $11 for a gauge from an american shop when the same exact gauge was $.99 shipped from China.
Found out my blades were delayed in shipping so it will be a couple weeks till they show up. I spent my budget already for parts or I would order some more locally. Sux cause I will be going full time at work next week which means I will only have Sundays for flight now.
Got a spare set?
I ordered 4 pairs of fibreglass blades. Fortunatly the place I ordered all my other spare parts from sells the Align ones for $11 for 3 pairs shipped so next time I will order from them. They have such great deals and from the time I placed my order it was less then 3-days till it was at my door!
2200mah 20c w/Deans Ultra on it already= $22
6x main shaft=$9
10x fly bar=$12
4x metal gear/BB servos (Tower Pro)= $26
Carbon fibre blade balencer=$12
6x feathering shaft (new style)=$10
8x tail rotors= $3.50
5x 150T main gear=$6
All these prices were including shipping. They also sent me a bonus bag with 2 free belts, some tracking tape, some balencing tape and a screw set bag.
They will get all my buisiness from now on. I still need an extra tail fin and some linkages but I am pretty well covered for everything else.
I'd Still check to make sure the gyro is set in the right direction. It still sounds like it's reversed. If the gyro is set in the right direction, there should be NO fast rotation of the heli without rudder input. It will either be wagging of the tail in place (Gain too high) or slow drift (gain too low) Having the tail kick out and spin the heli after a rudder input, but with no direct rudder input is the gyro is reversed.
The gyro is trying to stop the movement from your input when you let go. If it's reversed, it sees the motion and applies a correction, and that correction is wrong...but the gyro doesn't know that, it just sees the rotation rate increasing, so it increases it's correction...making it worse, and repeat until you have a spinning top.
Tail control is a combination of servo and gyro performance...but changing from one set of cheap servos, to another set of less-cheap servos isn't going to make a significant difference in the holding performance of the gyro. Just isn't going to happen. If there is ANY violent reactions to inputs, something isn't setup right.....Still sounds like the gyro is reversed.
I'd still check via the tail method. It isn't going to hurt.
Like I said, it doesent do that any more. I will double check in a couple minutes though. I had to switch the radio from normal to reverse to make the tail servo go the right way. Are you saying I should switch it back in the radio and then reverse it on the servo instead?
Ah, now I see. Holding the heli and giving it a little throttle and rotating it I see what you were sayingaboutthe gyro. I reversed it and now it counter thrusts in the right direction. I dont have main blades yet but I notice the tail rotors pitch is trying to make the heli turn right a little. I assumed when rotors are on it that it would need a little counter clockwise thrust to counter act the main rotors. I may have dialedin too much though and may have to shorten the linkage a little.
You can't dial in the tail without having main blades on.
Your getting too impatient Bill. SLOW DOWN. Your just going to hurry up to the next crash.
The weight of the blades swinging creates the majority of the torque that the tail needs to overcome. If you set it up without blades on (Try to set up the gyro gain) it's going to be off, and your going to need to do it again.
Also, you shouldn't be spinning the system up without blades in it really, either. Most likely, you won't cause damage, but running the power train with the weight and drag of the blades allows the motor to be spun up quicker than intended and possibly, given the quality of the speed control, can lead to over speeding the motor and possible other damage.
Setting up a gyro for simple hovering is simple, assuming it is in the right direction. Start at ~50% gain (I assume it has a small adjustment on the gyro itself, and your not setting it via the radio). Spin it up until it gets light on the skids. If it rotates counter-clockwise, the gain is too high. If it stays in about the same place, but has a slight, or strong "wagging" it is too high. The perfect setting is to have the gain set just below the wagging point.
Do you have a Rate Gyro or a Heading Hold Gyro....do you know?? If you have a Heading Hold (or AVS) gyro, then the setting will hold throughout a battery pack. If it is only a rate gyro, the gain setting is conditional on the headspeed, so as a battery pack decays and voltage drops, the gyro doesn't do as good of a job. You will see drift at the end of a pack that you will have to accommodate for. Also, you setup a rate gyro a bit different than a AVS/HH gyro. A AVS/HH will accommodate for a non-ideal mechanical setup, a Rate gyro is setup in tandem with the mechanics.
Another tip/comment. Most cheaper gyros are piezo-electric gyros. They can be susceptible to temperature changes. Meaning, with the seasons changing, it isn't a bad idea to make sure that you give the heli a chance (an hour or so) to soak at the outside ambient temperature before flying if there is a drastic temp difference between where it was stored and outside. Anything more than 20*F, I'd give it a chance to warm/cool to outside temps. Worst that will happen is that the tail performance will vary as the gyro changes temps.
Higher end Gyros, GY-401, JR770, Spartans, GY601..etc, are MEMS technology and aren't susceptible to temp deviations
I figured I couldnt set my tail servo just right untill I had main blades on. All I have reallybeen doing is getting everything else perfectly level again with the new servos. Horns at 90* and all the links straight. The reason I was asking about the tail is I didnt know if I was supposed to set the center point of the servo as the center point (no pitch) on the rear rotor or if the rear tail needed to have a certain ammount of pitch to counter act the main blade spinning or if the gyro did that as well.
I have a head lock gyro, its not a high end one but from what I have read on some RC sites the versionI have is pretty decient and stable.
When I get the blades I will just spend a couple packs sliding it around on its training gear and getting the trimming down.
I also switched the pitch/throttle curve back to stock specs with 0* at low stick and 5-6* at mid stick with 11-12* at max stick. Throttle is 0,40,65,85,100.
I loaded those specs into my simulator and have been practicing with a 4-7mph wind. I have spent 12+ hours on the sim since my last crash and am going to be more careful. As much as I have learned in just the last couple days has made the crash not so bad. I am much more familiar with the bird and how to set stuff up, not scared of it.
I havent crashed the sim in a few days eaither and allot of the movements are coming automatic instead of thinking about it.
I figured I couldnt set my tail servo just right untill I had main blades on. All I have reallybeen doing is getting everything else perfectly level again with the new servos. Horns at 90* and all the links straight. The reason I was asking about the tail is I didnt know if I was supposed to set the center point of the servo as the center point (no pitch) on the rear rotor or if the rear tail needed to have a certain ammount of pitch to counter act the main blade spinning or if the gyro did that as well.
I have a head lock gyro, its not a high end one but from what I have read on some RC sites the versionI have is pretty decient and stable.
When I get the blades I will just spend a couple packs sliding it around on its training gear and getting the trimming down.
I also switched the pitch/throttle curve back to stock specs with 0* at low stick and 5-6* at mid stick with 11-12* at max stick. Throttle is 0,40,65,85,100.
I loaded those specs into my simulator and have been practicing with a 4-7mph wind. I have spent 12+ hours on the sim since my last crash and am going to be more careful. As much as I have learned in just the last couple days has made the crash not so bad. I am much more familiar with the bird and how to set stuff up, not scared of it.
I havent crashed the sim in a few days eaither and allot of the movements are coming automatic instead of thinking about it.
You always want the servo arm as close to 90* as possible in neutral position. That allows even motion both left and right, as well as even torque from the servo. With your radio, your only able to do this with mechanics by tweaking the servo location and by rotating the arm on the servo. With a higher end radio, you can input Sub-Trim, which lets you minutely adjust the center point of the servo electronically.
With a Heading Hold/AVS gyro, you only need to set the mechanics up for the tail slider to be about in the middle of travel when the servo is centered. The Gyro will accommodate any required deflection at idle by itself.
With a Rate mode gyro, you need to set the servo up for a 90* center point and then you need to adjust the tail slider position by moving the entire servo up and down the boom to find the proper neutral point for the mechanics. With a rate gyro, you need to set up the mechanics in a manner that at the servo center point, the tail has the proper deflection to offset hovering torque without requiring gyro input. A rate gyro will only stop rotational acceleration, not rotational velocity. So, if it is setup and it has a drift, the gyro won't stop that, it will stop it from increasing however. So, you need to have the tail setup right....and as I said before, a disadvantage to a rate gyro is that the initial conditions change as the battery drains, so what holds really well at the beginning of the pack, may not be as good at the end.
I went through that all because there are some HH/AVS gyros that respond well to being setup initially for rate mode. I don't know if the gyro you have can be changed between modes or not. Not saying you HAVE to set it up for rate initially, but it can't hurt. Basicially, setting up for rate makes the gyro work less during simple hovering and forward flight, because 90% of the work is done in the mechanical setup.
Another thought. Your going through getting servo arms at 90* and links level....good job, becomes critical when you setup for idle up mode and start running more aggressive flight to have a symmetrical setup. Do you understand what is meant by "Blade Tracking". Do you know how to adjust the tracking to make sure the blades are swing in-plane?
Sim time is good. Even with a cheaper/free sim. However, it's not 1:1 even with the best of the sims. There is definitely significant benift of the higher end sims (Real Flight, Phoenix) over the cheap/free sims (xheli, FMS) but anything can be benifical. One very important thing is to realize that it is NOT 1:1. The best use of a sim is to learn orientation out of it. If the sim is a good representation of your model, the next best use of a sim is to learn energy management (momentum). But don't fall into the trap that if you can fly in the sim that you can fly in the real world.
Yes I am familiar with blade tracking. My understanding is its more important then balencing. Again I wount know for sure untill my blades show up but I think I have itvery close. I used my old carbon fibre blades for the pitch and tracking settings. Only their ends are broken so for leveling everything out they worked well. I had to adjust one of the links on the blade holders to bring one side up a full turn.
After they were level and all the rest of the links and servos were at right angles and the slider was at dead center position, the blades were at zero pitch as well. I fine tuned it some more and got it where it should be good. In idle up the mid stick is zero pitch and it looks to go about 20-22* at full stick and negative 20-22* at full down.
I realize the sim will be different, they all are. It has helped to load my helis settings though. The sim used to be air born at half stick but my heli didnt become air born untill just over half stick, now the sim is the same. The only thing is I know the heli can piruette ALLOT faster then the sim can. I am mainly just learning fine controll and transition between flight and hovering on the sim. I figure if I am hovering in real life and the heli gets a little out of hand and I start to fly it then I need the skills to bring it back to hovering without over correcting like I was. At least in the sim now I can do a few laps keeping the heli level through the turns and transition to foreward flight and then bring it back to where I want it to hover and re land it in a 2' x 2' box.
I really am correcting before the heli (in the sim) gets out of shape. I used to drift in a 6' area, now I can keep the drift to under 2' in any direction.
Thanks for all the help and keep it comming.
BTW, I dont have a rate gyro. I have a head lock gyro. The gyro is an Art-Tech Head Lock Gyro V3, part number AT-EG301.
"This gyroscope uses digital PID control method. It has a built-in temperature compensation circuit and thus greatly reduces the impact of temperature change on the midpoint offset. It has two working modes: locked mode and standard mode. With multi- gain controls and many adjust methods, this gyro can perform head- lock function easily. It is easy to fit different kinds of helicopters. It is a good choice for hovering, flying routes, reverse flight and other stunt flying."
So it seems I need o set the middle position of the servo as zero pitch on the tail rotor and then use the gain adjustment to correct for spin? More gain for counter clockwise and less gain for clock wise?
Yes. On a 450 sized heli, tracking is MUCH more important. Having badly out of track blades will cause additional stress, variations in input and at worst vibration. On a 450, the weights and sizes are so small and the headspeed is so high, that the balance of the blades really has minimal impact. Sure, if there were REALLY REALLY out of whack it could be a problem, but I don't even balance blades anymore for my 450's.
One point of clarification....any Heading Lock/AVS gyro is inherently a Rate gyro with additional "smarts" applied. Meaning, nearly all HH/AVS gyros can be caused to operate in Rate mode.
I say this because, looking at the manual for your gyro, you indeed are in that case. You need to pay attention to the gain settings you input into the gyro.
Your gyro has the remote gain lead plugged into the receiver, I assume. Gyro's typically operate in 2 manners to switch between modes. One being a physical switch, the other being the gain setting. Yours is the latter.
If your gain is 50% or lower, then your gyro is operating in Rate mode. If your gain is 51% or higher, your gyro is operating in Heading Hold mode. the gain that you input via the radio is NOT the true gain that the gyro sees......so don't fall into that trap. If your gain is currently at 75% on the radio, the true gain is going to be somewhere around ~50% Heading Hold. 50% on the radio is 0% HH gain, and the 0-100% gain is mapped to the 50%-100% settings on the radio.
clear as mud??
Take away...make sure your gain is above 50% at all times, or your not in AVS mode.
Not sure exactly how you program this on your radio. Do you see a LED readout of the setting, or it a mechanical pot?
Unfortunately, it doesn't appear that the gyro has a LED to indicate current mode of operation. Most have this for a clear indication of mode. One way to easily determine which mode it is in is to power up the system without turning the motor and put full deflection to the tail and let go. If your in rate mode, the servo will instantly return to center as soon as you let go. If your in Heading Lock/AVS mode, it won't go back to center...it may creep around slowly towards center, but it won't snap instantly back.
Gain settings. Your heli WANTS to rotate opposite the rotation of the main blades, I assume they rotate clockwise, thus it wants to rotate counter clockwise. If your gain is too low, it will drift counter clockwise. If it's too high, it's not going to rotate clockwise, but it will have a wag to it.
If it is rotating clockwise, it is because of one of two reasons. 1 - your in rate mode, and your mechanical setting is too aggressive. 2- you have trim on your rudder channel on the radio. With rate mode, trim isn't a bad thing. In AVS/HH mode you DO NOT want trim on rudder channel. In HH/AVS mode, any trim is seen as instructed input...thus it will command a slight rotation.
Good plan with the sim. Learning to have clam understanding of what is happening and how to account for it is important and is the sim's forte. Just don't fall into the trap of faulting the helicopter and the hardware for the lack of fidelity of the sim. Meaning, don't expect the real thing to fly like the sim...no matter how much tweaking you do. Sure, you can get it close in particular conditions, but no matter how much work you put into it, there is always a distinct difference between sim and real life...even if it is just mental...which accounts for a lot!!!!
Good Luck, and keep pressing forward. Holler if your run into anything more.
I've just got back from vacation, and I still have 2 helis that are in need of repair!!!!! Damnit!!!!
Yes, it creeps back to center and chatters if I move the heli at all. The gain plug is not connected to the reciever. Never was and the plug is not long enough. I really need to get some blades to properly set this thing up.
Thats how many RPM it gives per volt. Since I have 11.4v batteries I can get up to 42,750 rpm.
Well the new main and tail rotors showed up today so in a bit I will balence and mount them but its raining very hard out so now flying.
Ill pull teh Lincoln out of the car port and trim out the heli but it wont be leaving the ground today.
Thats how many RPM it gives per volt. Since I have 11.4v batteries I can get up to 42,750 rpm.
Well the new main and tail rotors showed up today so in a bit I will balence and mount them but its raining very hard out so now flying.
Ill pull teh Lincoln out of the car port and trim out the heli but it wont be leaving the ground today.
A car port is plenty big enough to do hovering exercises! Maybe you're is different....but I've never been able to properly trim my heli without leaving the ground. Prop wash causes too much trouble.
Well you are right my friend. Laft/right, foreward/back needs to be a couple feet up to trim correctly but I think (may be WAY wrong) as long as the swash plate is level and the helicopter it balenced (its center point is directly below the main shaft) that the trimming will be minor. The tail trim is what I need to set now. I am really curious how much thrust the tail needs in a neutral position so I am anxious to set it up.
I just got done balencing the main rotors. All four pairs were remarkably balenced already. All they took was a piece of tracking strip on the light side and they are now perfectly balenced. One pair needed nothing. Sure they took a couple weeks but for the price they are really not bad at all. I wouldnt use them for comp flying because I can see some waves in the finnish but for training they will do.
Linear Mode
