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Old Sep 06, 2009, 09:37 AM
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KCV6's Avatar
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Hey Jack,

Definately moving the upper blades up would help and wouldn't be that difficult to do. The inner shaft is quite simple and I suspect a fairly standard size. It's a shame from manufacture it wasnt 10 to 15mm higher as this would probably do the job, most of my breaks are the last inch or less at the tip. You can actually see whats happening when the lower blades clip they flex up far enough to cause a blade strike. CF blades would still be the best bet, but it does suck that there aren't any around this big. I think I'm getting lazy. LOL. I'm still impressed that so long as the flybar is shortened by 15mm each side and it's travel limited with a bit of ORing cord I cant get it to hard blade strike in flight.

I ran the 3D Pros and after 2 12 min flights the tips are already permenantly bent up like yours were.
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Old Sep 06, 2009, 09:57 AM
It flies!!! ... so who cares ?
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Quote:
Originally Posted by KCV6
...
It's a shame from manufacture it wasnt 10 to 15mm higher as this would probably do the job, most of my breaks are the last inch or less at the tip.
...
CF blades would still be the best bet, but it does suck that there aren't any around this big.
Sounds like a case for the Xtreme Rotorhead to me ... Xtreme is the only company, that actually uses standard length shaft and gets the extension from head design (pleeze, anyone who already has this head, correct me if this only is true for little Lama, but NOT for BIG) - this way you could get exactly the 15mm you ask for Mark.

Who knows about CF blades?!? Make the same statement again by the end of October ...

regards,
Sven
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Old Sep 06, 2009, 11:33 AM
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Quote:
Originally Posted by KCV6
Hey Jack,

Definately moving the upper blades up would help and wouldn't be that difficult to do. The inner shaft is quite simple and I suspect a fairly standard size. It's a shame from manufacture it wasnt 10 to 15mm higher as this would probably do the job, most of my breaks are the last inch or less at the tip. You can actually see whats happening when the lower blades clip they flex up far enough to cause a blade strike. CF blades would still be the best bet, but it does suck that there aren't any around this big. I think I'm getting lazy. LOL. I'm still impressed that so long as the flybar is shortened by 15mm each side and it's travel limited with a bit of ORing cord I cant get it to hard blade strike in flight.

I ran the 3D Pros and after 2 12 min flights the tips are already permenantly bent up like yours were.
I know you have access and the talent to make some CF blades, but if stiffness if critical, you might try wooden blades. Getting the shape and lift you want could be very tedious, but might work out for you nonetheless.
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Old Sep 06, 2009, 11:44 AM
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Quote:
Originally Posted by erdnuckel2
Sounds like a case for the Xtreme Rotorhead to me ... Xtreme is the only company, that actually uses standard length shaft and gets the extension from head design (pleeze, anyone who already has this head, correct me if this only is true for little Lama, but NOT for BIG) - this way you could get exactly the 15mm you ask for Mark.

Who knows about CF blades?!? Make the same statement again by the end of October ...

regards,
Sven
That's a true statement for the little Lama. A larger version of their Lama 4 head design would give a slight increase in distance between blade sets(just increase all dimensions proportionally according to scale difference). Once that head is made, the sky is the limit since you can make your own shafts to any length you'd like out of music wire(you just need to add a flat on top for the head and two on the bottom for the inner shaft gear collar). I once thought of making Lama 4 shafts out of 2mm drill rod, but was told that the music wire works better. The music wire is VERY cheap to buy at a hobby shop, but might cost a bit to ship since it comes in 3ft lengths here in the U.S. I don't know what the situation is in other countries. If you end up making an inner shaft that is longer than your outer shaft, just get some tubing to make a spacer to take up the difference. In the case of the small Lama, you can use an old outer shaft to make an appropriate spacer.
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Old Sep 15, 2009, 09:33 AM
Merry xmas
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Now where was I

Sorry been work pre-ocupied of late and also setting up the newly arrived CB180D.

Sven I believe you are correct about the head being an extended head with standard size shaft. If I do go down the path of extending I will be using a machined spacer that goes over the standard shaft. Probably 316 as a cheap way of proving the concept.

Jack, the piano wire option with a short stainless sleve will work really well as a final solution. As I have access to a machine shop the spacer is something I can make up at say 15mm extension and slowly machine back by a couple of mm each day until I hit the desired length. If it slips or breaks I can just turn up another one.

That said my CF blades are looking good, I just need to make one more piece of tooling for final cutting of the blades grip end so each pair will track correctly. Basically the grip end of the blade is oversized (thickness) and the tooling is stainless so the faces can be blocked flush with the tooling face in a repeatable fashion. There is very little flex in the blades so I believe the strike condition on my heavy handed landings will be eliminated anyway. I should also be able to take the servo extent back out to 100%.

I had a bit of a play with strut configuration as well, I have opted for a "bump resistant" aluminum CopterX Black Angel rear strut and a standard Align/CX/HK plastic front. Main reason behind this was to stiffen the rear up a bit while still allowing some flex in the front. I will do some more "blade breaking" landings to see how this configuration holds up The helo actually takes off forward now due to the back being about 3mm higher.

Mark
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Old Sep 15, 2009, 10:09 AM
It flies!!! ... so who cares ?
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Quote:
Originally Posted by KCV6

Sven I believe you are correct about the head being an extended head with standard size shaft. If I do go down the path of extending I will be using a machined spacer that goes over the standard shaft. Probably 316 as a cheap way of proving the concept.

Jack, the piano wire option with a short stainless sleve will work really well as a final solution. As I have access to a machine shop the spacer is something I can make up at say 15mm extension and slowly machine back by a couple of mm each day until I hit the desired length. If it slips or breaks I can just turn up another one.

That said my CF blades are looking good, I just need to make one more piece of tooling for final cutting of the blades grip end so each pair will track correctly. Basically the grip end of the blade is oversized (thickness) and the tooling is stainless so the faces can be blocked flush with the tooling face in a repeatable fashion. There is very little flex in the blades so I believe the strike condition on my heavy handed landings will be eliminated anyway. I should also be able to take the servo extent back out to 100%.

I had a bit of a play with strut configuration as well, I have opted for a "bump resistant" aluminum CopterX Black Angel rear strut and a standard Align/CX/HK plastic front. Main reason behind this was to stiffen the rear up a bit while still allowing some flex in the front. I will do some more "blade breaking" landings to see how this configuration holds up The helo actually takes off forward now due to the back being about 3mm higher.

Mark
Hi Mark (and welcome back - good to hear from you again)

Question - you say 15mm and "cut back" ... how much of an extension are you planning to do (in mm) as the usual extension they sell for the Esky BigLama is 20mm - but I DO know that the distance between the rotor planes is greater in case of Walkera helis to start with ...

The company I know in Germany makes extended outer shafts with 5mm exterior diameter (I think they are 205mm long) - catch: I am not sure if it will be possible to attach walkera gears (I have to "talk to my source" first ... a little later today)

Cool that your heli now lifts of "like the real thing" - must be fun to see you fly it ... when are you going to let us enjoy your progress in form a little video?

Regards,
Sven


EDIT:
OOOPs, forgot to ask about the blades - can you please elaborate a little more on that one, as I don't quite seem to understand the thing about thicker roots and all that ...
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Old Sep 15, 2009, 10:51 AM
Merry xmas
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Hey Sven, thanks

Yeah I'll be interested to hear some more about the outer shafts. A one piece ready made solution is always the better option IMO. I still have to play around with distances between blade sets, I'm pretty sure even 10mm will do the job with standard blades but more importantly I believe with CF blades that have a lot less flex the extended shaft won't be needed at all.

I am at the point now where I will finally do some video as I am very happy with how it is flying. It's pretty much doing what I want (other than the breaking blades bit. LOL)

I'll take some pics soon of the CF blades so you can see what I mean. I have one set laid up ready for final shaping and ballancing. I'm still deciding on weather or not to sweep the tips back (30 degrees on the last 30mm, not so much from a improved lift point of view, but more from a reduces damage on light strikes point of view. I've got a few metres of 190 CF weave so I can play around a bit.

Cheers.. Mark

PS hows your new build going? been following the thread just not had much of a chance to comment.
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Old Sep 15, 2009, 11:58 AM
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We've seen videos and most are of the heli in a small space and not doing a lot. I'd be interested in seeing it in a park or field where it can flex its muscles. That means fast forward flight. It just seems hard to imagine a 450 size coax that's got agility and some speed.
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Old Sep 18, 2009, 03:06 AM
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Quote:
Originally Posted by KCV6
Came up with a nice simple but fairly effective method of reducing the flybar pivot.

I had some O-ring cord of varying thicknesses laying around, so I took the flybar retaining cap off. The 400 is like most Walkera setups where a cap with vertical slots in it retains the flybar and limits how far the flybar pivots. I cut a piece of cord to the same width as the slots and cleaned the cap in acetone (it is a metal head) I used the trusty Loctite Prism (CA) to then glue the cord in place. Picture to follow at some later time once I get it "tuned".

This has reduced pivot by a reasonable amount and acts as a nice bump stop type damper. This weekend should prove interesting as with a bit of luck I will get the time to put it through its paces.

Mark
Any chance of some pictures. I have a 400D and would like to be able to get into more dynamic flight.

I have a stock flybar and head, so should I shorten the flybar and restrict it's movement?

Thanks, Paul
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Old Sep 18, 2009, 09:27 AM
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Paul,

Definately taking 15mm out of each side of the flybar and reducing the pivot increased it's agility without sacrificing too much stability. I'll get some pics up ASAP, I've been seriously bogged down with work over the last few weeks so havn't really done much flying and not had a chance to write up any of the other mods.

Mark
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Old Sep 18, 2009, 10:28 AM
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Thanks very much
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Old Sep 20, 2009, 08:29 AM
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Ok,

Had another play with the flybar limit and found using small 3mm heatshrink and CA to hold it in place works just as well if not better than the oring cord.

Undo the two retaining screws in the flybar retaining end cap and pull the end cap off. Cut a couple of lengts of heatshrink, or 1 piece of o ring cord and CA it down in the groove. see picture below to see where it ends up. This mod is easily removed by soaking the cap in acetone which will disolve the CA meaning you can play with different thickness until you are happy with how it flies. I found 2 "layers" of heatshrink works well, any more and it requires a lot more input to get back to hover from directional flight.

Cheers. Mark
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Old Sep 21, 2009, 12:11 AM
Merry xmas
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First real failures

Put in almost an hour of blade breaking on the weekend and had my first 2 failures not associated with Pilot error.

Failure 1. I suspect this is more due to the number of times I have planted the 400D into solid objects. The original 1500mAh 20C 3S started to puff after a flight. Pressing it between my fingers it made a nice squelching sound so rather than risk it causing damage it was banished to the salt water bucket for a week or two before disposal. I couldn't be bothered trying to save any of the 3 cells, it's simply cheaper to buy the Turnigy and flightmax packs from Hobbycity.

Failure 2. Part way through a flight I noticed it was getting a lot louder than normal and started to show signs of TBE so I stopped the flight and stripped the gearset and shafts off. The outer shaft main bearings top and bottom had both started to crap themselves. They were very notchy. Out with the bearings and in with a new set and all is good again. This occoured at about 15 hours. Will be interesting to see how the replacements last. I also suspect the amont of times I've hit solid objects wouldn't have helped.

Cheers... Mark
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Old Sep 26, 2009, 10:16 AM
Merry xmas
KCV6's Avatar
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laid up the first set of CF blades

Finally got around to making the first set of CF blades. Not much else to do over the next few days, it's been raining and hailing here with serious gale force winds. Soon as I get some clear weather I'll try out the new blades. I've started with a set about the same thickness as the originals, coming in at about the same weight.
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Old Sep 26, 2009, 11:06 AM
It flies!!! ... so who cares ?
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Quote:
Originally Posted by KCV6
Finally got around to making the first set of CF blades. Not much else to do over the next few days, it's been raining and hailing here with serious gale force winds. Soon as I get some clear weather I'll try out the new blades. I've started with a set about the same thickness as the originals, coming in at about the same weight.
could you PLEEEZE show a picture Mark??
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