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Old Aug 10, 2009, 08:34 AM
The END.....ha!
KCV6's Avatar
Australia, SA, Edinburgh
Joined Aug 2009
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Walkera LAMA 400 series mods and discussion

Ok, I know there are a few threads out there, but no real threads pulling all the info together so here goes I'm happy to be first off the rank to dispel some of the myths surrounding this bird.

I'll start with a bit of a first day review of what you get and how it flies.

About 4 weeks ago I decided to covertly acquire (the married ones will understand) a new Lama 400D for the bargain price of $149 USD RTF from the good folk at ehirobo/walkera parts. As it turned out a friend purchased it on my behalf but then insisted that I keep it as a gift..... what a champ!

My primary goal with this build was to come up with a good flycamone2 platform that would work outdoors in moderate conditions. It would sport a decent fiberglass 450 canopy, it would accept larger capacity battery packs, it would have durable landing struts and above all would survive medium impacts with minimal damage.. So far I have achieved all of this... including the medium impacts. hey it's a helicopter they crash eventually.

First off the rank was to investigate and charge the supplied battery. A rather unassuming 1500mAh 20C 3S LiPo pack with red HXT 3.5mm gold pin connectors. Using my trusty Turnigy Accucel-6 50W charger I charged and discharged the pack a few times and much to my surprise discovered the pack actually ran at just above 1600mAh.

Being all too familiar with the usual Walkera 4/3 in 1 setup with servo rate adjustment and gyro sensitivity adjustment being the 2 potentiometers located on the RX, I figured I'd do a bit of indoor flying and try to get these sorted. All too easy. The rate adjustment was set from the factory to about 1/4 of it's travel not permitting much movement of the swash. I remedied this by turning it to it's full extent (CCW) even before applying power.

Time for the first flight. Out of the box the 400D is nose heavy and wants to fly forwards. This was trimmed out so I could get a reasonable hover and the tail was then flicked side to side to check the sensitivity. As usual it was a bit "spongy" and required some minor tweaking to get the best results with a fairly good tail lock. All in all the helicopter handles very nicely but something has to be done about the incorrect C of G. Time to venture outside on a fresh pack and work out the flight time.

As I'm still setting up I decided to wait till just before sundown when it's nice and calm. I flew from my backyard taking the helicopter up to about 40 feet and doing run out and turn and run back etc over the house. After 10 mins I bought the helo back down to around 5 feet and just scooted around the back yard until the 4 in 1 cut in and slowly removed power from the motors. Time was 13min 25 seconds. I was pretty happy with this and decided to call it a day.

Attached are a couple of pics of the helicopter half modded. It has since changed more, but I will get to that over the next few days.

Cheers... Mark
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Last edited by KCV6; Jan 27, 2012 at 10:35 PM. Reason: now going brushless
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Old Aug 11, 2009, 09:57 AM
The END.....ha!
KCV6's Avatar
Australia, SA, Edinburgh
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4 in 1 RX settings. how to do them

As with all Walkera helos, they come from the factory capable of flight but certainly not perfectly tuned up. Pretty much all their CX 4 chan aircraft have both a gyro sensitivity adjustment pot and a servo extent pot. (refer to the photo below). Usually the servo extent pot is set for less than half the available travel of the servo. In the case of my 400D the travel pot was only at 1/4 off no travel so the helo had very little swash movement full stick. The second photo shows just how short the servo arms are on the 400D factory setup. They are also not properly centered. Any Helo I get the first thing I do is check all fasteners are secure, all main drive gears are properly locked to their respective shafts with no slop. They are terrible at the factories for not doing screws up properly. The second thing is to check the lash on the main gear and Motor pinion gear. The Third thing I always do is pull the servo arms from the servos, disconnect the motors, set all trims to zero (throttle zero is always fully down not in the middle). Now bind the model and re-position the servo arms so they are at 90 degrees and re-fit the screws. Adjust the linkages so that the swash is perpendicular to the main shafts. Turn off and re-connect the motors.

The RX2419 fitted to the 400D is the first Walkera RX I have come across that actually has pots with end stops. This is great as when it comes to adjustment you can just turn it too the CCW end stop for extent adjustment and if you get carried away with the sensitivity adjustment you can only go so far before it stops. For example on the 4#3, 5#10 and 4G3 the pots are continuous with no stops so it's easy to get lost.

I CAN'T STRESS THIS NEXT POINT ENOUGH! before adjusting the sensitivity, get a small sharpie or other permanent marker and mark the factory position of the slot. This way if your adjustments are causing the tail lock to get worse and you get lost you always have a reference to return too.

I recommend for the first few setup flights you set the extent pot to its midrange. Just wind it fully in both directions and then put it in the middle.

For the sensitivity get the helo trimmed for a good stable hover. Observe the tail. If it is twitching the sensitivity is set too high and should be backed off very minute turns at a time negative (-) until it hovers stable. If the tail starts to turn by itself after a while requiring constant trim update to maintain no rotation hover then the sensitivity is probably not high enough so once again minute adjustments at a time positive (+). The other trick with this is to shut it down, make the minute adjustment and leave it for at least 5 mins for everything to cool back down. Remember to re-zero the trim before re-binding and trying again. Now that it appears to hover fine with good tail hold, apply sharp flicks of the tail in both directions so you get about 20 degrees of rotation. Literally flick and release the stick. If the tail drifts after you have released the stick then gradually increase the sensitivity. Once again if the tail shudders after the flick briefly then turn the sensitivity down. There is a compromise here and no 2 RX/ helo combinations seem to be identical. Eventually you will settle on what is the best compromise.

More to come later...

Cheers... Mark
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Old Aug 12, 2009, 09:22 AM
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Reliable skids at a reasonable price

OK

So far the 400D has flown well, once everything was checked, tightened and tweaked.

Most off the shelf RTF helos tend to have skids and struts that seem to break on hard put downs. I was looking through my box of spare bits and figured I'd have a crack at fitting the standard T-rex clone (HK, CopterX etc.) skids that come with the 450 Version 2. If I was to break them they are a dime a dozen and easily purchased plus they are more flexible and generally don't break. Keeping in mind I wanted the helo to sit about 5mm higher off the ground for flycam clearance, I pulled a set out and checked the hole spacing for the fasteners to the main frame and the height. It was not bad. Out with the drill and the holes were opened up a bit inboard by about 2mm. i.e. slotted towards the middle.

The standard screws were trial fitted and so long as you get them to bite in flush with the plastic you get about 2D (2 thread diameters of thread length) of thread to screw into the main frame. From an engineering point of view this is certainly enough for the rear screws that go into metal tabs. For the front ones which go into plastic I decided to use some spare M1.5 socket head screws that were about 3mm longer.

I fitted the struts and the skids using the standard rubber retaining rings and then drilled 2 1mm holes through the front set either side and fitted a small set screw to lock the skids in place and stop them rotating. Refer to the pics below.

Cheers... Mark
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Old Aug 12, 2009, 10:53 AM
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Batteries C of G and the battery holder

I already worked out that the standard 1500mAh 20C LiPo pack is quite good, definitely up there with the Zippy and Turnigy packs I use. But I figure as the helo was heavy anyway I might as well have a play with some different packs.

I'm not a big fan of the way most RTF helos have their battery wires hanging out underneath, looks untidy. The Lama400D has the same sort of carrier with a hinged downward opening door as the 53Q and 53Q3 that allows the battery to be slid in from underneath and behind. They are always a tight fit, the edges of the pack always get caught up and the leads end out hanging in the breeze underneath.

There was also the second problem of the C of G being too far forward of the main shafts making the helicopter nose heavy. I pulled the battery tray base plate out of the helo and decided to cut the front and rear retaining "steps" off with the plan that the battery pack could then be slid in from the front with the canopy off. More like the sort of 450 setup with the leads from the battery connecting to the leads of the speed controller at the nose so it's all hidden when the canopy is re-fitted.

I happened to find, in my collection of stuff, a Zippy Flightmax 2200mAh 20C 3S pack, and a Turnigy 1600mAh 20C continuous/30C burst 3S pack. These are both great packs and from memory can be acquired from HK (hobbycity) for around $16 USD. If not then they are damn cheap anyway. I cut the deans connectors off and replaced them with HXT 3.5mm plugs as used on the 400D. These are also available from the likes of HK. Note the Turnigy pack already had a 3.5mm HXT plug on it, however Walkera in their great wisdom decided to wire the + and - pins opposite to what most others do so I cut it off and re terminated it.

I added a piece of Velcro (genuine Velcro Velcro... as it sticks like the proverbial to a blanket) hook to each pack and a piece of loop to the hinged door. The plan was that to insert the battery, first flick the door open, slide the battery back while checking the C of G and once it was in the correct position close the door so the two pieces of Velcro would contact and hold the pack in place. This works brilliantly for all 3 packs.

Zippy also do a cheap flightmax 1800mAh pack the same dimensions as the 2200 pack.

Have a look at the pics below. Ignore the piece of Velcro mounted on the outside underside of the main frame nose section for now, that’s where the cam goes and I'll get to that later. Also you will note some small pieces of foam. These were added to prevent the canopy from vibrating. The Flycamone2 picks up enough noise without buzzing rattling sounds as well.

Cheers... Mark
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Old Aug 12, 2009, 03:13 PM
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This heli has the 370/380 brushed motors. Being a HBFP guy, we always went to a Slo-Max motor(Team Orion), but it has been discontinued. Most of us have finally realized that our only option now is to either go with the Eflite CP Pro 2 motor, the Xtreme 380 motor (can blow the 4-in-1) or go brushless. It'll be interesting to see how long the stock motors last and how well they perform. Does it handle wind well?
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Old Aug 12, 2009, 03:38 PM
It flies!!! ... so who cares ?
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Quote:
Originally Posted by kodak_jack
This heli has the 370/380 brushed motors. Being a HBFP guy, we always went to a Slo-Max motor(Team Orion), but it has been discontinued. Most of us have finally realized that our only option now is to either go with the Eflite CP Pro 2 motor, the Xtreme 380 motor (can blow the 4-in-1) or go brushless. It'll be interesting to see how long the stock motors last and how well they perform. Does it handle wind well?
Why would a Xtreme 380 motor blow the 3in1 from a heli that already flies with 11.1V battery Jack? ... or, the 4in1 of WHICH heli are you talking about?
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Old Aug 12, 2009, 09:31 PM
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Hey Jack,

I'm trying to keep a log of flight time to get some idea of "durability" of components. As things wear and need replacement I'll log it so I end up with a bit of a MTBF on failures. This will include all component failures not related to controlled crashing

The 4 in one is powered from the Brushed motor controller in the usual unknown way if you know what I mean, i.e. battery to controller, controller to motors and RX, RX 6 pin output to controller. I want too hook a data analyzer up to the 6 pins out of the RX that control the brushed speed controller to see just how easy a brushless conversion will be. Just the fact there are 6 pins for 2 channels is almost promising.

It certainly handles wind a lot better than say the 5#10 but it is a lot of work as with all single swash CX's. Definitely not a problem in 5 to 10, but that’s to be expected for 650+ grams. I have lightened the flybar weights by 1.5g each and am waiting for a spare flybar to turn up so I can have a play with length. Hover is at about half stick and there is stacks of power to spare after that point.

I live in a gully on a hill above the Adelaide plains so we either have a constant light breeze or really gusty conditions. Gusts are always a problem.

If my package turns up tomorrow I should be able to get some in-flight video over the weekend.

Cheers... Mark
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Old Aug 13, 2009, 04:20 AM
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Quote:
Originally Posted by erdnuckel2
Why would a Xtreme 380 motor blow the 3in1 from a heli that already flies with 11.1V battery Jack? ... or, the 4in1 of WHICH heli are you talking about?
The Xtreme motors draw more current than what the 4-in-1 can handle, in some cases. My experience is with that motor on a HBFP. There have been numerous instances of that particular motor destroying 4-in-1's. Although this is a different heli, the potential is still there for damage.
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Old Aug 13, 2009, 04:24 AM
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Originally Posted by KCV6
Hey Jack,

I'm trying to keep a log of flight time to get some idea of "durability" of components. As things wear and need replacement I'll log it so I end up with a bit of a MTBF on failures. This will include all component failures not related to controlled crashing

Cheers... Mark
MTBF? You sound like a Reliability guy! I have a BS Degree with a concentration in Reliability Maintenance. Too bad the need for this skill in a manufactring environment is all but gone around these parts. All manufacturing has gone to the same area where these heli's are made!!!!!!!1
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Old Aug 13, 2009, 09:21 AM
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The Xtreme 380 motor is a "hot rewind" and requires higher rpm to keep it happy than standard 370s. The stock HBFP blades have too much resistance, which makes the X380 work too hard. With other blades, or cut down stock blades, there is no problem.

I don't know about the Lama 400 motors, but other Walkera brushed motors I've seen are also "hot rewinds". Also since the blades used on this coax are similar to cut down HBFP blades, I don't think an Xtreme 380 motor would be a problem.
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Old Aug 13, 2009, 09:22 AM
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MTBF.. yes sir old habits die hard.

LOL yep.. The art of calculating MTBF is all but gone everywhere unless a customer specifically requires it and it's called up as a CDRL item. Even then most try to waiver it citing it's a combination of already proven Off The Shelf parts. The killer is the safety analysis and the addition of sinage that warns of the warning signs sharp edges.

It seems easier to put a mandatory warranty period that's negotiated if you are selected as a preferred tenderer. My how things have changed. MOTS and COTS seems to be the way of the future. And yes I know exactly what you mean and can't help but agree.

Cheers.. Mark
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Old Aug 13, 2009, 09:39 AM
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Motors

Balr14, I can confirm that after 13 mins of mixed hover and some mildly spirited flying the motors are barely warm which is usually a good sign. I work with a guy who use to re-wind and re-brush slot car motors with propper cut down carbon brushes. Another advanteage of working where I work.. there is always a workshop corner to hide and do "stuff" at lunch and smoko. He was saying he would be interested in pulling a few of these Walkera motors down as they come close to dying and having a crack at re-building them. He's running a Nine eagles (blade clone I believe?) with very few mods but like most of us the bug to tinker doesn't take long to show itself. . Anyway after a run the 400 motors are quite cool compared with say the 5#10 motors run the same duration. This of course doesn't say anything for how good or bad the "brushes" are. I guess when the inevitable happens and they start dying I will pull them down and have good look at number of windings and guage of windings and what sort of brushes are used... there is an access hole throught the PCB on the top (bottom) and the brushes to be honest look like thick copper arms.
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Old Aug 13, 2009, 10:11 AM
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Canopy decisions decisions.

By this time in the modification I had pretty much decided I wanted to use one of the readily available and usually very cheap fibreglass 450 class Canopys. I actually had recently got a couple, each for well under $10 as additional Items when placing orders for yet more 450 parts for my CopterX/HK hybrid I was building up.

These fit like a glove with very minimal modification as can be seen in the first pic. Also they already have a cutout in the underside that looked like a good place to fit a velcro clad block for mounting the flycamone2.

The original Walkera canopy is the usual thin but reasonably robust plastic type (possibly polycarb) with cut slots to clear the front skid strut. This single slot either side that opens out to a "elongated hole" made it a bit difficult to slide the canopy on and off once the retaining gromets had been pulled from their stays at the back. I decided a straight slot the same width as the thickness of the replacement 450 struts was in order. To prevent the canopy from rattling around I adhered a couple of bits of of old Pelican case "pluck and place" foam cube to either side frame at the front.

I positioned the canopy on the struts and marked where the 3mm holes were to be drilled at the back to re-use the original rubber retaining gromets.

There is not much else to say on the canopy other than I guess it's a personal choice thats up to the individual. I personally like it as far as proportions go. It is a bit wider but much the same length as the original and a good cheap option.
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Old Aug 13, 2009, 10:27 AM
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Quote:
Originally Posted by KCV6
there is an access hole throught the PCB on the top (bottom) and the brushes to be honest look like thick copper arms.
This is a problem with smaller Walkera motors. Those copper arms are not thick at all and don't have carbon pads. The copper looses tension due to heat and they have less contact surface than carbon pads. They start to fail very quickly. In a 4#3B they last only an hour or two. They aren't much better in other Walkera helis. Maybe their 370 size motors are better. I hope so. I'm thinking of buying a CB180Q.
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Old Aug 13, 2009, 10:34 AM
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Mounting the Flycamone2

Things are starting to take shape well. Now for the Flycamone2 mounting. I wanted to use the supplied mounting base however soon discovered the lens assembly would hit the ground if was tilted all the way forwards. As I had no intention and in fact no way of having a spare channel to either drive the cam head or take stills I decided to cut the base off of the mount and sand a section out to make it shorter. I removed the small PCB and wires and pins. I then re-glued the two pieces back together with CA. The plastic is very porous and glues rock solid with Loctite "Prism" 406.

I wanted to make sure the cam head was located in line with the bends in the skids or possibly a bit further back, so there was no chance of the lens assembly dragging on the ground in nose down slides. This meant the mating Velcro pad would have to lay over the front strut underside. The struts are near enough to 4mm thick where they attach to the main frame so I cut and CA'd 2 pieces of 2mm thick white styrene plastic together, shaped them up and marked on the underside of the battery carrier where they would be bonded. The battery carrier has some features here for mounting the Lama 400 (Dauphin) fuselage. I got the Dremel out and cut these off and ground the underside to a nice flat surface. Once again this plastic is great for gluing with Prism.

I trial fitted the canopy again and marked out the additional clearance required in the front hole on the underside and used the Dremel and barrel sander to cleanly open the hole up.

All in all the cam fits nicely and all the switches are easily accessed without having to move anything around. I have taken some video, however nothing very exciting yet, but the picture quality is not bad, very little vibration. I didn't use the Velcro pads that came with the flycam, as I mentioned earlier I pretty much use only genuine Velcro brand as the acrylic adhesive meets military standards and requires a lot of heat and effort to remove.

Cheers... Mark
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