Well, after picking up the pieces of my Lama after it fell from 50 feet (seemed like 300) due probably to a radio glitch (the motors just stopped dead in mid flight), I decided to try use my Spektrum DX7 radio and replace all the on-board electronics and, while at it, go brushless.

While waiting for my motors, controllers and gyro to arrive, I quickly put together something as 'proof of concept' with whatever I had available. See what it looks like in the attachment!

The only remaining original parts are the servos (which I will change), the main frame and part of the tail (proof that this may have been a Lama 3 V3 at some point).

Here are the changes I did, over a few months:

Frame
After 2 tail changes, I put together a simple carbon rod tail which works pretty well - meaning it does not break with my abuse. Same for the landing skids and base plate. Its just a few pieces of 1.5mm carbon plate cut out, drilled and glued together. The electronics moves around far less - not a bad thing for gyros. Glueing the carbon parts means the assembly sometimes breaks apart with shocks (as its hard but brittle) but at least they dont break. I have been using this platform to test things and try to do some fancy figures with a lama. Rule number 1 with helis: If theres a tree within 100 feet of you, the wind will blow the heli straight into the tree. Corolary: if there is the least hard object on the way which can do more damage than the tree, the wind will blow it into that first!

Rotor mecanism
Replacing the standard blade holders, swashplate and central shaft was a real headache. As soon as all was replaced, the Lama was simply uncontrollable - doing large circular motions which were tough to compensate - the 'toilet bowl' effect. After trying everything I could find in the forums on this, to no avail, I changed part by part back to the original plastic ones to try to identify the culprit. Turned out it was the upper balde holders. Put all the aluminium parts except the top blade holder and it works well for me. I tried a generic copy of the esky aluminium upgrades and thes are pretty decent.. especially since I paid 20$ for them!

Blades
I tried quite a few different make blades and now use the Xtreme ones - 8$ a pair is a lot but i manage to keep them for a long time. In 4 months, I have broken 1 set (4 blades), mostly trying out new tricks. Needless to say, the tricks failed!
I have not yet tried the carbon fibre blades, so hesitant am I to put 50$ for 12g coal and epoxy. However, I can now break blades on demand - and it takes 10 seconde to do it. Just send your (well, my) Lama full speed forward, wait a while till it gets a bit of speed, pull back the elevator fully and wham! It never fails.
Does anybody have an idea for tougher baldes or an acceptable source of carbon or fibre blades? This is really one of the key things that limits coaxial performance - blades hitting into each other. The Xtreme central shaft is a bit longer than the standard one so t his does help a bit.

Motors
I used the stock motors for a long time, till they eventually burnt. I replaced them with the Xtreme motors where one can change the brushes. They are still working and I have some spare brushes just in case. I am reasonably happy with them - they seem long lasting and smooth. Consumption does not seem affected (although I have not measured) but there is not much noticable difference in power.
On order are 2 Fiegao 12mm diameter brushless motors at 17g and 25$ each - not too bad if they last 3x longer than stock motors. We will see!

Electronics

Contrary to the E-flite CX2, which uses the same 2.4 GHz made by Spektrum, the E-Sky electronics is not the best. The 4-in-1 is a wonderful low cost piece of hi-tech and it can be separated into 2 parts - the receiver and the gyro/esc for the 2 motors. It does lots of things but not very well.

For the receiver, I put in a Spektrum AR 6100 6 channel receiver weighing 3.5 g. I used 2 30A E-sky ESC (Electronic Speed Controler), one for helicopters and one for airplanes - thats all I had available ! The Spektrum transmitter needs to be programmed to control both ESC/motors so that
1) when the power is increased, it controls BOTH motors
2) when the rudder is moved, it increases one motor and decreases the other.

I tried with 30A ESC, much too big - a 10A should be sufficient and have them on order - with some interesting side effects as one was for helis, the other for planes. For some strange reason, the heli ESC does not allow Gyros to be connected in series, whereas the plane gyro does.

The Gyro for direction (yaw) is placed between the rudder channel and one of the motors. Normally the gyro should affect BOTH motors, but it seems to work OK if only one motor is controlled. I have it on the lower rotor motor which seems to work best.

The roll and pitch gyros (not needed but it was fun trying) are placed between the receiver and the servos.

There must be about 20 feet of wire linking the different components - I will clean it up when I put the definitive components.

Batteries

Having removed the 4-in-1 electronics, this can now run on 2 or 3 cell batteries. In fact, the gyros prefer 11.1V batteries. I have tried running a Lama on a 11.1V battery and it seems to work pretty well. I did not do long tests but nothing burnt and if needed, I do runs with 11.1V batteries if my 7.4V are all discharged and I'm totally desperate to fly.

One interesting point with having 2 ESC is that you can put 2 small 11.1V (or 7.4V) batteries, one for each motor.

Tests

The whole thing, without batteries, weighs 250g - the stock Lama with the battery weighs just 230g. The stock battery weighs something like 40g so this thing is 60g heavier than the stock. With Xtreme blades but otherwise all standard, the Lama has a lift of around 270g.

Now how much lift do you think I got? The best was with 2 small 20C 11.1V batteries - I stopped increasing the power when I got to 520g of lift!!! There was not much vibration but the noise was sufficiently atypical to get me worried about burning the motors. I dont have any spares here! The blades were also bending a bit too much. With 7.4V batteries it was in about 360g lift. The increased lift with 7.4V is certainly due to the higher efficiency of the ESCs. The rest of the lift is increased voltage.

Does it fly?

Well, before trying, trimming it was a bit of job - the walkera gyro is always a bit tough to tune and the different ESCs on the motors, with the gyro on one, was not trivial. You have to start giving power with the rudder to the extreme left to get both rotors running and then slowly come back to neutral on the rudder as power gets to take-off range.
The rotor revs can go high so its best to have a well balanced head and blades and make sure the screws are all in with a drop of loctite!

Does it fly? Well, YES! and pretty well. It lifts up very rapidly, is very stable (not surprising, with 3 gyros), responds very quickly to controls. Even with a single servo, it is quite easy to fly, although it flies more like a single rotor micro-heli than a coax. I did not manage to keep it up without a gyro!

Outside, even in 10-15 mph winds, it stays very controlable. It moves very fast forward, and a bit slower backwards - not sure why. My guess for now is that it does over 25 mph - I have never seen a coax move so fast!
My speed runs were very short lived though since both times I tried to slow down too fast and the rotor blades collided - instant death on a coax!

Conclusion

Well, that about concludes my summary of the prototype. I will post when the next version is ready. It should look half decent.
The changes will be : single low weight gyro (at 40$ a piece, I wont put 3 for fun), 12mm brushless motors, 10A brushless ESC, fast servos and a new frame.

I really need to solve the blade problem before going outside! Anybody a pro at making carbon, fibre, wood or metal blades ?

Any other suggestions / comments more than welcome! Just dont tell me the looks suck! I know that already!

Wicked[X(]

Wicked indeed! [>:]

Here is my first attempt at making aluminium blades - all by hand! The photo shows a very rough unfinished blade and the equivalent Xtreme blades. As my aluminium profiles were not quite wide enough, I made them a touch longer. I cut these by hand, filed them, put them together and made sure they had identical sizes. A full hour's work! The weight is identical to within 0.1g and the CG to within 0.5 to 1mm.

Below is the table that summarises the lift caracteristics of the blades I have:

Supplier Weight Lift
Xtreme 5g 208-218 g
Microheli 2.5g 175g
Stock E-sky 3.5g 185g
Aluminium proto 10g 190g

To measure this, I put the heli on a scale, attached with elastics and one pair of blades only. I take the heli to full speed and measure the initial weight and apparent weight at full speed. The difference is the lift.

Does it fly? YES! To test I put the Aluminium blades at the top and Xtreme blades at the bottom. Had I thought of the testing earlier on, I would have started with Alu blades for the bottom rotor - to see how control is exercised.

It is a bit more sluggish than normal - but after a 5 minute flight, both motors were running at their usual temperature. I look forward to testing with 4 aluminium blades.

Caution: If you try this, just be TOTALLY careful that there are no kids, spouses, pets, plants and furniture within a 1 mile radius. Aluminium blades are 10g a piece and if they come flying off, they can do considerable damage. Just being hit by a blade will be dangerous - absolutly NOTHING to do with the plastic blades. Hitting an object with the blades can do a lot of damage to the heli itself.

Next step, while waiting for my motors, frame, etc. is to make the lower blades and try to make them lighter - down to 5 to 6 g.
Have fun and take care!


Hugues

PS.. any mad hatters around to help with blades that wont collide in mid air?

I saw your list of upgrades and I noticed it said something about the center shaft. Did you upgrade to an extended center shaft? The extended shaft gives more clearance between the blades to prevent blade strikes. There are several places that sell them here is a link to on of the sites
[link]http://www.slickzero.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=ESL020&Categ ory_Code=[/link]
And here is some ones home made solution on rc groups
[link]http://www.rcgroups.com/forums/showthread.php?t=633819[/link]

A quick update - i did the second set of blades today - this time same length as Xtreme blades, and just a bit narrower near the center. They weigh 11g each.. real heavy weights. Photo next to Xtreme blades and details showing the curve and narrowing. The edges are still rough.. I only polished the leading edges.

On a standard Lama 4, they have up to 170g of lift, compared to the Xtreme blades at 190 to 200g.

On my turbo charged Lama 3, they have 200g of lift with 7.4 V batteries and.. wait for it, 340g with an 11.1V battery. The Xtreme blade stops at 330g lift. As I hoped, the metal blades continue increasing lift with revs while the Xtreme blades taper off.

With both sets of blades on, my turbo lama 3 has 450 to 480g lift with Xtreme blades and 515 to 525g lift with the aluminium ones. These results are approximate as I did not want to burn my motors out so just went to full speed for a short while.

I expect to get in the 600g lift when I put on the brushless motors! Cant wait for them to arrive!

Ah.. does the heli fly ? YES! I only tried it on my V4 standard lama (the turbo lama 3 needs some reparation of the landing skids) and as you may expect with such heavy weights, it is as stable as a.. Lama 4 V4! Actually a bit tough to get it turning and there is quite a bit of momentum.

So my next step is to reduce the weight by half. Should keep me busy drilling - I need to find a very thin coverring film. Any ideas ?

By the way, has anyone tried measuring the lift of the carbon fiber blades ? Anyone tried them?


Hugues

Just saw the photos were missing..

Thanks for the info, ih8nixon : I have an extended Xtreme shaft on order - but why use a simple solution when u can make your own blades? lol

The inner shaft is pretty thin so lengthening it can result in it being bent by a rough manoeuver in flight but it will reduce blade collision death.

Why?

Hmmm.. why what, RedGN?

OK, ok.. I know I'm crazy but here goes. In order to use normal blades, for example those of the Walkera 52 micro heli, which is a 7 channel machine normally capable of doing 3D, one needs to set the angle of attack to somewhere between 5 to 10 degrees - which is not possible with standard blade holders.

The potential interest of this is to be able to use different blades and do trials with different head speeds / blade angles. On larger machines, acrobatics are done with higher head speeds.

Anyway, so I made a blade holder where I can manually adjust the rotor angle up to about 12 degrees - see photo for the first draft. I made a few mistakes when doing it so its a bit messy.

With a 7.4V battery on my turbo-Lama 3, it has 170-190g of lift, which is a bit lower than the Xtreme and aluminium blades. At 11.1V, we get ot 310 to 330g lift, again, just a bit below the alu or Xtreme blades.

The lama is very nice to fly with this - I tried with a mix of xtreme and symetrical blades, as I only did one blade holder. For now, the best performance is with a fairly steep angle, in the region of 10 degrees. My guess is that I did not get the head speed high enough for optimal angle, which should be in the region of 5 to 6 degrees.

More tests will follow when I FINALLY get my brushless motors!

Keep flying!

Hugues

Well, here it is.. looks a bit better than the last version and runs so SMOOTH.

It uses the Lama V3 frame, a mix of Esky and Xtreme alu parts (all Esky in the picture), the Extreme canopy, tail and landing skids, 2 outrunner BL motors, 2 10A ESC, 2 fast digital servos, the E-sky 0704 gyro (while waiting for the 0704A) and a spektrum 6100 receiver. Weight without LiPo is 190g.

It works well on both 7.4 and 11.1 V Lipos - achieving an incredible 660g lift on 11.1V 20C battery.

Flying on a 7.4V is like flaying a normal Lama - just more precise and faster. On 11.1V, it takes off on 1/3 throttle and can shoot up vertically very fast.

Fitting the 18mm diameter brushless motors was a bit of a challenge - they are 1 to 2mm too big to fit comfortably. My 12mm ones are here but I dont have the pinions yet.

Getting better responsiveness with increased power was also a bit of a challenge - and is still pretty much WIP - although some of the tweaks really do help.

I still need to try it outside with decent winds. I expect it to drop a bit when the gyro reduces speed to compensate the rotation, as the gyro is only linked to one rotor.

OK, enough for now.. time to play!


hugues

does the lama get faster forward/sideways with the extreme motors?
reply please!
// Anton

Anton,

There is some speed improvement with the Xtreme motors - although the major advantage is they run cooler and you can change brushes. From the noise of hte motor, they do seem to run better.

If you have the Lama 4, the servo arms have been cut which means u cannot have better control of the movemnet. Putting longer arms improves speed.

Try making the linkages between the swashplate and lower rotor holders more rigid (I did this with a pair of 3.5mm ball links and a tiny piece of threaded rod) will give you better speed.

If you dont have them, the Xtreme blades, because they are harder and better profiled, do give extra lift and forward / lateral movement.

With some electronics experience, you could try to put a bigger mosfet to drive the motors. In mine, I put external ESC which are much more efficient.

Overall, there will be two things that improve flight speed: lift and your ability to make the bottom rotor blades move and change pitch.

Hope this helps and gives u lots of ideas to try!


Hugues

thanks man that gives me some help for my lama v3! but what do you mean with "rigid". im not so good at inglish.. Im from sweden you see..
thank you! // Anton

Rigid means it does not bend. The standard Lama linkage is made from fairly soft plastic - nice because it does not break but not nice because it makes control much 'softer' - not good for going fast!

Hope this helps!

Hugues

yes this helped me. thank you
//Anton

Thanks for posting this. I have been looking for a way to take my Lama 4 brushless.
Where did you purchase your gyro and motors?
Don