Heliguy Forum - RC heli forum

My Esky Lama V3
Some notes by Garth Nicholson (novice!)

I have had my Lama V3 for a few weeks now and I think it is a great helicopter on which to learn the basics. I have modified mine slightly, which required some re-tuning and dismantling. I have gained advice and ideas from several forums including this one, as well as coming up with my own ideas. Some of the stuff here you might have read in previous posts. I thought I would bring everything together for the benefit of anyone who is thinking of buying a Lama, or who might be having some of the same issues I have encountered. I have included a few pictures and a short video clip of my modified Lama (short because I was holding the camera with my right hand and controlling the heli with just my left!).

I am a total novice regarding rc helicopters, having only owned a 2 channel PicooZ before the Lama. What follows is therefore mostly only my experiences and some of my own theories. It may be incorrect, and I cannot be responsible for any damage you might cause to your model or yourself as a result of using this informaton! I would also like to Thank Joe and Joel at Heliguy, and Scott Helmann for their advice and Scott’s permission to use his excellent balancing article.

Flying characteristics

Seems very good to me…stable hands-off hovering is always possible, but the yaw trim changes throughout a flight, and can require frequent trim correction. This happened from new, even after adjusting the 4-in-1. It’s no big deal though – it maybe even sharpens your reactions a bit! Flying indoors is fine, but you should watch out for turbulence (see later). Likewise outdoor flying is great, but only in zero wind. The slightest breeze or gust will just carry the model away. The only major crash I have had was outdoors in this situation. I would also think that in cold weather, the landing gear would be susceptible to snapping, the tail boom even more so. The yaw drift seems a common problem, but if you do plenty of forward flying circuits around a room, I found it is easier to instinctively correct yaw, because you are always inputting yaw anyway, and any correction needed is either more or less ‘turning’ in the circuit direction. This applies equally when tail-in or nose-in. When hovering you have to actively decide which way to move the stick, see if you are wrong, then correct it! That probably doesn’t make much sense, but it works for me!

I have a total of about 8 hours flying now. No new parts were needed, apart form a top blade set after fitting the CNC upgrades (see later) and crashing into things several times. Average battery life is 12 minutes, but I try to keep to 10 minute flights to preserve the batteries. With the heatsink mods I made, I can fly continuously for 10 minutes without any excessive heat build up in the motors, although the batteries do get warm. The original Esky battery is softening slightly now, but it has had a few heavy impacts as a result of the CNC episode.


Training Gear

I got to the hovering stage without training gear. For the first couple of batteries I was just hovercrafting (new word) around a smooth floor, getting the feel of the controls. The first actual flights were just hops of around one second duration. By the time I’d fitted the training gear, I think I was past the time of most benefit from it. It is however very good for protecting your blades against wall strikes, so I would recommend it. I had to fit mine to the skids using wire ties, since the brackets did not fit properly.

Setup, balancing and tracking.

From what I have read on several forums, chances are your Lama will fly fine ‘out of the box’. At some stage, perhaps after a heavy landing or crashing into something, you may want to check its setup. This is how I do it:

I bought a cheap electronic balance accurate to 0.01g, and found the blade pairs to be pretty much perfectly balanced (to within 0.02g) I bought a complete spare blade kit at the time of purchase, and it seems that they are sold as balanced pairs ie if you use blades from different sets you may get an imbalance. C.G. was also fine. There is an excellent procedure for balancing small helicopters(not Lama specific) by Scott Helmann in the accompanying .pdf file : You will see that Scott used a constant chord blade (ie leading and trailing edges parallel) for his example on finding the blade balance point, so he only needed to keep the blade perpendicular to the rule and put a white mark on one edge. Lama blades are smaller and tapered, so you will really need to mark both edges in order to get consistent placement on the rule. Also, I used a vertically set razor blade as the balance edge – it prevented the blades twisting off when nearly balanced.

Blade tracking has never really been a problem with mine so long as the blades are not too loose in their holders (i.e. no vertical slop). They must be free to rotate about their pivots however. Sometimes tracking can be slightly different from one flight to the next, especially on the upper rotors, so I don’t know what’s going on there. One time, tracking of the upper blades after a crash was way out, but on examination of the blade tips, they had become burred around the edges. Removing the burrs by scraping with a knife cured that particular tracking issue. Check the flybar for straightness by looking along it and also rolling it along a flat surface. The middle will dip up and down as you roll it if it is not straight. I found the best way of checking flybar balance is to snap it into its holder without the link attached, and see if it balances. The flybar should have little or no rotational movement, but be free to ‘see saw’ in its holder. The upper link should also be free to move. Any excessive slop in either the flybar mount or its linkage can cause instability. When the flybar is horizontal, check that the upper blade holders are also flat (adjust by lengthening or shortening the link). I found that adjusting this by eye is good enough. I found that if this link was deliberately made shorter or longer, vibration would increase dramatically, but surprisingly, stability wasn’t affected too much. Likewise, the swashplate should be perpendicular to the mainshaft – this will automatically level the lower blade holders (and vice versa). I found I needed to trim this to get it accurate by test flying, but initial set up by eye is good enough. You can check for vibration and balance in the components by gradually assembling the rotor heads and spinning them up individually. This way you can check the run-out in the shafts as well. Start with the main shaft, and spin the motor, add the swashplate and lower blade holders, check again, then add the top bearing holder, check again, then the inner shaft, then the upper blade holders, then the flybar. Anything which suddenly increases vibration is a potential problem. Add the blade pairs last, and check them individually. You can check shaft trueness by rolling along the edge of plate glass or some other smooth flat surface.

I occasionally lubricate the motor lower bushings and all the ball races with a tiny drop of 3-in-1 oil, and the gear sets and all ball joints / rotor pivots with a small amount of teflon dry lube.

If you find the screws are stripping the plastic threads in any of the components, you can apply a tiny drop of superglue into the hole and let it set. The screws will then tighten better than new.

By the way, if you forgot to mark the blades after dismantling, the top rotors turn anti-clockwise and the bottom clockwise (when viewed from above).

Trimming.

After fitting the CNC ‘upgrades’ I was getting diagonal movement when inputting left or right roll, making proper control all but impossible for me. After refitting the original parts I was still having control problems because I had changed rod lengths etc. If you have had a few major crashes, you may also need to make some adjustments to get your Lama flying properly again. What follows is my experience of how to set up a Lama. It may well be incorrectly thought out, but it worked for me!

Firstly, follow the procedure in ‘Setup Balancing and Tracking’ above, then test fly. This was a typical test flight for me:

Test Flight 1 : Stability improved, but still not right, got progressively worse over the course of a few minutes. However, blade tracking perfect & no significant vibrations. I had to use full back trim, and some right to get it to a ‘lumpy’ hover, but then my problem of diagonal movement with left or right input returned. I was stumped, but determined to sort it, since it flew fine before, and there are only a few adjustments you can possibly make.

Test flight 2 : Brought it to hover at eye level. What I noticed was a very slight rocking motion, both left right and front back. Almost imperceptible. I looked at the direction of the initial wobbles and adjusted the trims the opposite way incrementally. The situation improved after several attempts. I then landed and reset the servo rod lengths to give central trim again, and re-tested in hover. Vast improvement.

Test flight 3 : Repeated above process, and it is now hovering perfectly stable, with precise lateral and forward control – no diagonal movement! Success!!

Right or wrong, here are my conclusions:

1/ If you have a small amount of bad trim in the Lama, because it is so stable it will effectively cover the trim issues by constantly stabilising itself. This can cause a rocking motion in hover. You have to look carefully to see it, but in my experience you can have a good few clicks of trim before you get a constant movement. Before you get this, the machine will just rock slightly. It is similar to the stall motion of a fixed wing aircraft, but can occur in roll as well as pitch. If you try to move say forward or backwards in this state, you will be also moving in the trimmed direction. With mine it was moving left as well as backwards – this was because I had left trim initially, but it was ‘masked’. Once you remove the ‘hidden’ trim it becomes perfectly balanced.

2/ Turbulence is critical to these small machines. If you try looking for the tiny movements mentioned above after flying in a medium sized room for a few minutes you simply will not see them because of the unstable air. I would recommend an empty garage, hovering at eye level, and only for a couple of minutes at a time. When looking for trim issues, I found it best to concentrate on one axis at a time. If the heli is slowly rotating, physically move yourself around with it at eye level while looking for any other subtle movements e.g. right drift or backwards movement. This is another reason for trimming in a large uncluttered room. Don’t worry though, eventually you will end up standing still! *It is a good idea to wear safety glasses if you are looking closely at your model at eye level*. Sorry, but I am paranoid about my eyes, and having them near two sets of spinning blades unnerves me.

3/ If and when your trims are good enough for fairly stable flight, you should jump straight up on take off to something like eye level. DON’T try to trim based on the initial movement on lifting to a foot or so then landing – it will give false trim requirements which can start you on the wrong path.

4/ If or when you have used up about 3/4 of your trim, land and move the trims neutral, and adjust the required trim with actuating rods so that the servo arms are at 90 degrees again. This way you will get more consistent control about the servo mid-point because you eliminate the asymmetrical movement caused by the servo angle offsets.

4-in-1 adjustment

I have read that there are different types of 4-in-1 in different types of Lama, so beware before assuming which pot(s) do(es) what. On mine there are two adjusters on the 4-in-1: The upper one is the larger of the two, white in colour. This is the ‘yaw’ pot and seems to adjust the relative power to the motors to enable neutral yaw with the left stick centred. However, even if you set this pot perfectly, I found that I still get yaw drift throughout a flight. Maybe this is due to the 4-in-1 heating up, or something to do with the battery power changing. The lower pot is silver and much smaller. I don’t really know what it’s called, but I can tell you my experience of the effect of adjusting it. At one stage, I needed to adjust the yaw setting of my Lama, because I had run out of trim. I adjusted the small silver pot by mistake, and although I don’t know the theory of what the small pot does, I can tell you what effect it has. This is the sequence of adjustments I made:

1) By trial and error, I first set the large white (yaw) pot to give neutral yaw with the trim centred (extremely small adjustment by the way). 2) I then powered up to around 2 meters height and noted there was no discernable yaw either way under power. 3) adjusted and re-set (by disconnecting and reconnecting the battery) the small pot full clockwise and re tested under power to 2 meters. Again – no yaw either way. 4) While hovering I input full left yaw – the heli spun very fast anti-clockwise, then moved the stick full right yaw – the heli spun very slowly clockwise. I then centred the stick and the heli hovered – no yaw. 5) I then adjusted and re-set the small pot full anti-clockwise, and repeated the action in 4 above. This time, the heli yaw speeds were reversed ie very fast clockwise, very slow anti-clockwise. I then did the obvious thing, and set the pot by trial and error to give more or less equal yaw rates clockwise and anti-clockwise. At no point in the above did the yaw trim have to be adjusted to give stable hovering with the stick centred.

I have no idea if what I did was the correct or relevant procedure, but I can say that the Lama is flying better than ever (notwithstanding the fact that I am now a better pilot than when I first got it, so a direct comparison is difficult. Note that whenever you make an adjustment to either pot, you should disconnect and reconnect the battery in order to reset the 4-in-1.

To check the gyro : if you can hover at waist level in a reasonably stable manner, you can try gently holding the tail of the helicopter and swinging it left and right. You should be able to hear the motor noise change pitch as the gyro tries to compensate for the movement. Not sure what this achieves, but it is kind of cool. I suppose it tells you that the gyro is at least doing something.

Modifications I made to my Lama V3 (copy them at your own risk!).

1/) Motor Heatsinks Added : Adapted from the Maplin CPU heatsink kit. Attached using superglue around the edges and heat transfer paste in the centre. The motor cans and heatsinks were given a thin coat of matt black paint.
2) Cooling holes cut in canopy & fairing : Two large holes in the top, several smaller holes in the bottom, sides and back of the canopy. The top rear of the canopy was also cut right back, exposing the front motor heatsink. The rear tail fairing was cut out top and bottom, exposing the new heatsinks. The plastic covering was removed from the 4-in-1 in order to allow more airflow around it. The cooling mods significantly reduce the running temperature of the motors, hopefully increasing their life.
3) Battery tray : The original battery tray is not good – very fiddly to fit. Instead I threaded an elastic band through each locating slot and secured each end together with a loop of wire. In addition, I added a thin strip of aluminium through each pair of slots in order to prevent the battery from contacting the gear spigot in heavy landings.
4) Wiring : The original wiring was a mess. Servo and motor wires were re-routed, the excess wire looped into the cavity in front of the right servo. A piece of foam rubber was pushed in to keep everything in place. The wires could be shortened if you wanted to go to extremes, and this would save another few grams and make it even neater. Another piece of foam rubber was formed around the front of the 4-in-1 and secured with a self adhesive pad to offer some protection in the event of a crash. Also, after refitting the canopy, two strips of adhesive tape were added to keep the lower split holes of the canopy together in the event of a crash. Normally the canopy will pivot upwards around the securing screws in an impact, since the lower attachment holes will just ‘un-clip’. The tape resists the canopy lower holes separating, making the canopy more of a protective structure for the 4-in-1. The aerial was made into a loop, placed underneath the 4-in-1 tray, and secured with thread. It is worth doing a range check if you alter the aerial routing: With the helicopter on the ground and Tx switched on, check servo operation while gradually walking away from the model (don’t take off!). If the servos stop responding or start chattering while still in visible range, you’ve got problems and should try re-routing the aerial.
5) Painting : I could not live with the original ‘seasick green’ colour scheme. Mine is loosely based on French/Royal Navy colours, dark blue with fluorescent red details. The servo side stickers were removed, and the servos cleaned. I un-peeled the shockingly bad canopy stickers and removed the glue residue with WD40. I then washed all parts that needed painting in hot detergent. The bottom and rear edges of the canopy were masked and painted, the framing was added using strips of pre-painted adhesive tape. The red area at the front of the canopy was masked and sprayed light grey first (because it is visible as the canopy floor) followed by matt white base coat and two coats of florescent red. You should use a white base for fluorescent paints, otherwise you will need many heavy coats. The number ‘42’ and insignia decals were spares added from a Revell Alouette kit. The tail rotor and guard were sprayed yellow, with red stripes on the blade (as seems standard for many Alouettes). A coat of satin varnish was applied to all painted areas – I masked the clear parts of the canopy before doing this. I think the satin finish makes it more of a model and less of a toy! The main rotor tips were painted yellow. All paints were Humbrol. I used an airbrush for the the yellow, the red fluorescent paint and the satin varnish. The rest was brush painted.
Future additions might include an engine, propshaft & windscreen wipers, again from the Revell 1/32 scale Alouette plastic kit.
Currently, my Lama weighs around 215g with battery (according to kitchen scales), the manufacturer’s weight is also stated as 215g, presumably with battery, so the mods have not made a noticeable difference. Certainly the flight times are the same as when new, although I limit them to 10 minutes now.

6) Transmitter mods : I added heatshrink sleeving to the ratchet blade to make the throttle smooth, but I could still feel the detents even thorough this covering. Undeterred, I then removed the detents from the throttle quadrant with a file, removed the heatshrink and flattened the spring, this method is much smoother. It initially takes some getting used to because you can’t immediately tell if you moved the throttle while inputting yaw. It pays to bend the strip spring to give plenty of friction in the throttle lever, then you are less likely to move it by mistake. This mod. allows much more accurate power setting for consistent hovering.

The Tx charging socket is useful if you are using NiCads. My Futaba charger plug fits, but the plug has the wrong polarity (ie no charge lights came on). To get around this, I simply added a y-piece and another jack-plug to my charger lead, wired correctly for the Esky Tx, so now I can charge the batteries in-situ.

Esky CNC parts

For me, these were a big waste of time and money, and also add weight. To add insult to injury they are anodised in a very offensive purple colour. In my case, vibrations increased and there was more noise and less stability than standard. The flybar location is a joke, allowing at least 15 degrees rotational slop. In a crash (and you will crash) the flybar will probably bend because it cannot escape. There was around 1mm side-to-side play in both my blade holder assemblies, and the two-piece swashplate guide assembly could twist. If a blade strikes an object, this can jam the swashplate links causing even more grief (the standard plastic design is far a superior one-piece item). To fit the swashplate you have to re-drill the mainshaft locating holes, because on mine, the swashplate balls touched the motor terminals. I could not tweak the motor terminals enough to give clearance. Even after addressing all these faults (apart from the flybar location – I gave up at that point) and after extensive trimming as outlined above, it had a nasty habit of simultaneously rolling backwards and sideways when close to objects (or the floor)
If anyone is having trouble with the CNC parts, I would advise to start with improving the flybar location, or keep the standard centre shaft and flybar holder. I believe that this is probably the main issue.

Lithium Polymer Batteries

I had no previous experience of LiPo batteries before my PicooZ, and didn’t realize the safety issues and how carefully they should be handled. Fortunately, I’ve had no direct experience of the problems, but I have heard that if damaged they can swell and even catch fire with disastrous consequences to your model/car/ house/marriage. They should not be over-discharged since this can reduce their capacity. I fly only until I notice I need an increase in throttle to maintain hover, or when I see the red LED come on during flight. The red LED will normally come on at full throttle with a good battery, but will light during normal flight throttle increases when the battery is getting low. I believe the LED somehow indicates when the battery cannot supply the power demanded by the motors (although I can’t figure out how it does that). My batteries are always warm after a 10 minute flight. I keep the batteries in a metal case with a catch on it, and store it in the garage. My first charger (included in the Lama box) did not work at all, so had to be exchanged. No problems with the new one though.

In Summary

It’s a great machine. I am amazed to think that to date it has flown for 8 hours. That’s equivalent to flying for a whole working day for me – and believe me those days seem very long!

Thanks Garth!

Click here to see his Lama.

Last edited by Earlgrey on Thu Feb 22, 2007 3:20 pm; edited 2 times in total