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blades turn - no lift - 3/24/2012 3:32 AM   
Sibcoe


 

Posts: 3
Score: 100
Joined: 3/23/2012
Last Login: 3/27/2012
From: FremontCA, USA
Status: offline 		 I am incredibly new to this hobby, and after some research and local hobby store recommendation, I bought a KDS 450S RC electric heli.  First time flying with trainers on, I got a feel for the difficulty in even getting off the ground without tilting t one side, started to compensate, made some progress and felt good about it.  Charged up for next run - disaster - a training leg came off on a hard land a few feet up and bounced up into the blades, chaos ensued.  Bent the tail boom, split the rear fin, damaged the blades, damaged the rear blades, etc.  Took it to the hobby store and they gave me the parts.  I installed the new parts, took it outside, and bam - full power, full thorrtle, fully charged batteries, no lift.  When I let it sit for a few seconds at full power with no lift, I saw smoke come out of the front near the battery.  I paniced a bit, turned it all off and left it there to cool off.  Came back later and the battery was cool as was the rest of the heli.  Put a new battery in after checking everything and ran it al low power to see if the blades turned clockwise, which they did.  Took it to full power, same problem.  I switched the blades up to the other way round, same problem.  It was also spinning in a circle at one point.  

I took it inside and noticed what looked to be a cut wire black wire on the side of the battery receiver, so I spliced and reconnected it and put some electrical tape over it, just to test the theory that this was the problem.  Took it out again, same issue, no lift.

When the main blades turn, so do the small tail blades, full speed.

I also tried moving the sticks in every or any direction, nothing changed.  I did see that the various mechanical componenets responded to the sticks, but again, no lift.  

Any ideas what might be wrong.  I spent $50 today to buy the parts and if it is going to take a huge amount to repair after such a minor crash I am second guessing this hobby.  I really want to enjoy the challenge of learning to fly, but wasnt expecting it to be such a stress.  Smoking heli, dangerous lipo batteries, no lift etc.  I am feeling frustrated and would love to know what might be wrong.

Thanks in advance. 




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RE: blades turn - no lift - 3/24/2012 5:04 AM   
ACE_


 

Posts: 17
Score: 100
Joined: 8/15/2009
Last Login: 11/18/2012
From: moline, KS, USA
Status: offline 		I'm not certain about this KDS 450s but probably mechanicaly the same as a T-Rex, Check the bolt at the main rotor head that goes through the main shaft. I have sheared them on my T-Rex as well as my Blade 400. If thats the case, what happens is when you rev the motor up the blades will all spin up fast then as soon as you increase pitch the rotor speed stalls down not giving you the lift needed. If you banged it hard enough to shear the rotor head bolt you likely have a bent rotor shaft as well.

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RE: blades turn - no lift - 3/24/2012 5:26 AM   
Sibcoe


 

Posts: 3
Score: 100
Joined: 3/23/2012
Last Login: 3/27/2012
From: FremontCA, USA
Status: offline 		Thanks for the response.  I understand the KDS 450S is quite similar to the Trex.  I am not totally familiar with the various names of the parts yet, but I took a look at the main silver bar that runs through the main rotor housing down to the big white cog that turns from the main motor.  It looks totally straight and all the surrounding parts move as I would expect.  I dont know if it is normal, but when I plug in the battery with the handset on and connect it up, the battery receiver has a red light constantly on - is that normal?  Also a red light on the gyro.   

EDIT:  I tried it again, and on a smooth surface as the throttle ramps up the helicopter spins like crazy in a circle right at the point where it should have lift.  More throttle gives is more spin until it almost flips itself with spinning.  No lift of any kind though, and no amount of left stick correction changes anything.


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RE: blades turn - no lift - 3/24/2012 9:49 AM   
TakeshiSkunk


 

Posts: 407
Score: 100
Joined: 12/1/2008
Last Login: 1/9/2013
From: Coldwater, MI, USA
Status: offline 		Turn on throttle hold and just look to make sure the swashplate is moving up and down when you give collective input, and that this in turn is changing the angle of the blades. Also check your maximum and minimum pitch on the blades. Maybe look for stripped teeth on the main gear?

The spinning issue is weird. Makes the previous suggestion of a broken jesus bolt seem plausible, since if the main blade was slowing down when you add pitch that would throw the tail out as the gyro isn't expecting the sudden change. Hold the main gear still and see how much play there is in the head. The bolt we want you to look at is the one that goes through the bottom section of the central head piece and through the main shaft. Also you can't just eyeball the main shaft to make sure it's ok, remove it and roll it on a piece of glass or anything that you know is completely flat. 450s bend main shafts easily and you'll have issues if it's even a tiny bit off, though you would expect to see vibration if it is bent.

Don't get too down on the hobby because of this, what you're experiencing is pretty uncommon. You should be able to crash a 450 pretty hard for around 50 bucks and not have any weird issues repairing it. See what the LHS thinks, this problem will be much easier to figure out for someone that can get their hands on your heli and take a look at it.

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RE: blades turn - no lift - 3/24/2012 11:33 PM   
Sibcoe


 

Posts: 3
Score: 100
Joined: 3/23/2012
Last Login: 3/27/2012
From: FremontCA, USA
Status: offline 		Thanks for the help.  Took it in to my LHS today and well...lol

Main shaft was indeed bent, motor was burnt out because I installed the blade clamps the wrong way around, the motor belt was the wrong way around, lol.  The fly bar was bent, and the receiver wires were out of place.  All of this in addition to the issues I already mentioned above.  He started to take out an order form to make a note of the fixes then just decided, "hey let me fix it and we can write it all up later."  I am not looking forward to pikcing it up.  I do feel better that there are clear issues and I have learnt from it.

I feel much better about my learning, and much aggravated by the cost.  I am starting to think the $200 simulator with the controller included might be a good investment. 

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RE: blades turn - no lift - 3/25/2012 9:48 PM   
madmorgan


 

Posts: 747
Score: 100
Joined: 4/28/2011
Last Login: 12/27/2012
From: elmira, NY, USA
Status: offline 		dont forget the feather shaft that is usualy the easiest thing to bend ! i bet if u bent the main and the flybar the feather is no good.

_____________________________

if you dont know you better ask somebody ! usarmy active 1989-1997, 1990 desert sheild /desert storm, 1993 somolia .

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RE: blades turn - no lift - 3/26/2012 6:49 PM   
TakeshiSkunk


 

Posts: 407
Score: 100
Joined: 12/1/2008
Last Login: 1/9/2013
From: Coldwater, MI, USA
Status: offline 		Simulator is the best money you can possibly spend on helicopters. You'll never regret it at all.

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RE: blades turn - no lift - 3/26/2012 10:33 PM   
ACE_


 

Posts: 17
Score: 100
Joined: 8/15/2009
Last Login: 11/18/2012
From: moline, KS, USA
Status: offline 		Flight Simulator is a BIG YES. It can be hours and hours of good clean intertaiment on rainy days and is great for the kids too, My grandkids always want to fly when they come over.

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