Convert RC Lama XRB Knock-off
07-19-2004, 02:08 PM
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Convert RC Lama XRB Knock-off
There seem to be alot of activity on this subject recently. So I figured I'd shared what I know about it. But first a disclaimer. I've had the heli for about a month now and it is the only real rc anything I ever owned. Yea I owned 2 or 3 rc cars but they don't count since they were all digital controls, not like the analog version used for heli flying. I'm a total newbie when it comes to flying, but quite knowledgable in electronics.
The lama knock off is called the dragonfly and will be refered as such from this point on.
I've gotten the dragonfly to about 5 ft in the air but am too inexperienced to get it to hover for more then 5 seconds. The lama has alot of adjustments you can make to a stable hover where as the dragonfly has only the 4 trims on the Tx. For me, the trims were not enough. Even after I've set the trims at max, the dragonfly still wanted to rotate clockwise, move backward and to the right. I'm not experienced enough to make those adjustments in the air but on ground the above is very consistant. It should not be the ground effect unless one of you pros wants to tell me otherwise. Also as I slowly increase the throttle, I would alway observe the front of the landing gear would catch air first every single time. This could've been caused by CG. But as far as I can tell, the CG is not off by more then .75cm
The Tx
My Tx is 27mhz and the crystal is soldered on the board so it's not interchangable as stated by the seller. Also I think I've read somewhere, it's illegal for an RC aircraft to operate at 27mhz in United State, maybe Europe too. The Tx uses 8 AA batteries but you will get the same performance if you used 4 AA alkalines. The core of the Tx is just a microcontroller running at 5V. The mode of the Tx can be changed to 1, 2, 3, 4 or anything you like by using a pair of pilers and screwdriver. There is no sub-trims BTW.
Rx and Servos
The Rx is an all-in-one board. I call it all-in-one because everything is on the board, including the servos. What I mean is the electronics that's embedded in the servo is on the Rx board. I'm not sure if there is a gyro or not. I tend to believe there is no gyro because the manufacturer has cut so many corners so far. Because the 2 sets of blades rotates opposite direction, it only requires the 2 main motors rotate at the same speed to keep it steady so a gyro is not strickly necessary. But a gyro would still increase the stability of this heli. No adjustment is possible on the Rx
The lama knock off is called the dragonfly and will be refered as such from this point on.
I've gotten the dragonfly to about 5 ft in the air but am too inexperienced to get it to hover for more then 5 seconds. The lama has alot of adjustments you can make to a stable hover where as the dragonfly has only the 4 trims on the Tx. For me, the trims were not enough. Even after I've set the trims at max, the dragonfly still wanted to rotate clockwise, move backward and to the right. I'm not experienced enough to make those adjustments in the air but on ground the above is very consistant. It should not be the ground effect unless one of you pros wants to tell me otherwise. Also as I slowly increase the throttle, I would alway observe the front of the landing gear would catch air first every single time. This could've been caused by CG. But as far as I can tell, the CG is not off by more then .75cm
The Tx
My Tx is 27mhz and the crystal is soldered on the board so it's not interchangable as stated by the seller. Also I think I've read somewhere, it's illegal for an RC aircraft to operate at 27mhz in United State, maybe Europe too. The Tx uses 8 AA batteries but you will get the same performance if you used 4 AA alkalines. The core of the Tx is just a microcontroller running at 5V. The mode of the Tx can be changed to 1, 2, 3, 4 or anything you like by using a pair of pilers and screwdriver. There is no sub-trims BTW.
Rx and Servos
The Rx is an all-in-one board. I call it all-in-one because everything is on the board, including the servos. What I mean is the electronics that's embedded in the servo is on the Rx board. I'm not sure if there is a gyro or not. I tend to believe there is no gyro because the manufacturer has cut so many corners so far. Because the 2 sets of blades rotates opposite direction, it only requires the 2 main motors rotate at the same speed to keep it steady so a gyro is not strickly necessary. But a gyro would still increase the stability of this heli. No adjustment is possible on the Rx
07-19-2004, 10:28 PM
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RE: Convert RC Lama XRB Knock-off
Hi. I have a Dragonfly too and have had it all to pieces. I'm also into electronics. I read that it DOES have a gyro and I think I spied it on one of the two circuit boards inside but can't confirm that's what it was. But if you run the thing up while holding it, you'll probably see that it will go a bit berserk after a few seconds with the motor speeds. I believe (strongly) that this is the gyro sensing that the chopper is not turning when it thinks it should be and it gets into an electronic panic of sorts trying to make it turn while you're holding it steady. This theory is backed up (on my model, anyway) by turning the model slowly in the direction its pulling and the rotor speed settles down. I thought there was something wrong with it for the longest time until I figured it out.
However, mine still gets confused sometimes while flying and one rotor stops and the whole thing spins around at "90 miles per hour". Still flies, funnily enough (sort of).
Something to know about this model. The Hirobo XRB Lama's parts are direct substitutes (well the lower mast assembly is for sure and I'd bet anything that the other mechanical parts are the same. Except the blades for the Lama are styrofoam and EXTREMELY fragile! I'm making my own now and have had reasonable success. I've posted some info somewhere in here about it. Not quite perfect yet though and I'm not sure why but I think mine might flex a bit too much. I'm going to try a laminated blade next to see if I can stiffen it up and if that will make a difference.
However, mine still gets confused sometimes while flying and one rotor stops and the whole thing spins around at "90 miles per hour". Still flies, funnily enough (sort of).
Something to know about this model. The Hirobo XRB Lama's parts are direct substitutes (well the lower mast assembly is for sure and I'd bet anything that the other mechanical parts are the same. Except the blades for the Lama are styrofoam and EXTREMELY fragile! I'm making my own now and have had reasonable success. I've posted some info somewhere in here about it. Not quite perfect yet though and I'm not sure why but I think mine might flex a bit too much. I'm going to try a laminated blade next to see if I can stiffen it up and if that will make a difference.
07-20-2004, 05:46 PM
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RE: Convert RC Lama XRB Knock-off
Well I tried to make a laminated version and it was a total failure! I think I should have curved them before gluing them together. Adhesive bubbled up inside and destroyed them.
Anyway, I've given up on that idea for the moment because I found that sanding the leading and trailing edges into a sharp(er) edge and matching the blades better has made a HUGE difference (as I've just posted elsewhere in here). Problem solved.
8^)
Anyway, I've given up on that idea for the moment because I found that sanding the leading and trailing edges into a sharp(er) edge and matching the blades better has made a HUGE difference (as I've just posted elsewhere in here). Problem solved.
8^)
