Oversized Heli not flying. - RC Groups
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Oct 01, 2017, 05:59 PM
Scratch Builder
TrooperCooper's Avatar
Help!

Oversized Heli not flying.


Alright, so I am going to point out that I am kind of an expert when it comes to fixed wing rc aircraft, but when it comes to anything heli related, I have no clue. I have an older rc helicopter that has brushed motors, and runs off of a Lithium battery, and for some reason or another, it refuses to take off, as it simply sits on the ground and vibrates... even at full power. Yes, the Rotors are intact, and all motors are functioning propperly. It also does have the lightest possible load, as I have stripped anything that is not crucial to flight. Does anyone have any suggestions for this?
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Oct 01, 2017, 07:26 PM
Registered User
Steve Joblin's Avatar
Are you sure the blades aren't on backwards or the motor isn't spinning backwards? Is it a fixed pitch or collective pitch helicopter? Is it flybar or flybarless? What is the blade pitch at full throttle?
Oct 01, 2017, 07:30 PM
Scratch Builder
TrooperCooper's Avatar
Quote:
Originally Posted by Steve Joblin
Are you sure the blades aren't on backwards or the motor isn't spinning backwards? Is it a fixed pitch or collective pitch helicopter? Is it flybar or flybarless? What is the blade pitch at full throttle?
I know it is a fixed pitch, and the rotors should be on properly, but I have no idea what flybar is. Thanks for your help
Oct 02, 2017, 03:58 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
I'm guessing this isn't really what we would normally call a large heli (typically a rotor diameter over about 1100mm ? and weighing over 2.5Kg (5.5lb))

Anyway, if it's the 'toy grade' type of heli I'm guessing it to be then most likely either the battery is old and needs replacing or the motor brushes are worn out. Another thing to check if it's been used indoors is build up of fluff and hair tangled around shafts causing friction on the bearings. If the heli is old and hasn't been used in a long time then the battery is by far the most likely problem.

A photo of the heli would help confirm what type we are talking about.
Oct 02, 2017, 06:38 AM
Scratch Builder
TrooperCooper's Avatar
Here is the heli. It has never been flown indoors, I am planning to switch it over to a 3s lipo rather than the 2s lion it came with. It is toy grade as well, so if it is in fact the brushings, then it will probably get scavenged for parts.
Oct 02, 2017, 08:05 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
A 3S Lipo would cause the motors and electronics to burn out. A LiPo is just a form of Li-Ion, so if it came with a 2S you need to stick with a 2S. The heli itself is a coaxial so you would be better asking over in the coaxial forum, one of the regulars there might recognise what type it is.

A couple of observations. You have a mix of blade types (the black ones and the white) so you need to make sure that the blades are the same size and weight and perfectly balanced.

The fly-bar/stabiliser bar (the thing with weights on the end) doesn't appear to be centralised, maybe it's just the photo but one side looks longer than the other which will make it unbalanced.

Other than that all I can say is that it's not really worth investing too much in repair of this heli because it doesn't have much value.
Oct 02, 2017, 08:50 AM
Scratch Builder
TrooperCooper's Avatar
Quote:
Originally Posted by JetPlaneFlyer
A 3S Lipo would cause the motors and electronics to burn out. A LiPo is just a form of Li-Ion, so if it came with a 2S you need to stick with a 2S. The heli itself is a coaxial so you would be better asking over in the coaxial forum, one of the regulars there might recognise what type it is.

A couple of observations. You have a mix of blade types (the black ones and the white) so you need to make sure that the blades are the same size and weight and perfectly balanced.

The fly-bar/stabiliser bar (the thing with weights on the end) doesn't appear to be centralised, maybe it's just the photo but one side looks longer than the other which will make it unbalanced.

Other than that all I can say is that it's not really worth investing too much in repair of this heli because it doesn't have much value.
Yes I agree with not investing too much, as I would rather invest it in a quad or something like that, as they seem to be more reliable. The blades are the same, I just bought replacements for them, and they happened to be black rather than white. I would not have thought that adding one extra cell would burn out the electronics... I guess that makes sense because I recently burned out a quad motor doing the same thing. The flybar should be balanced because it is the stock bar on it, but it is a little bent (dont ask). I guess I could try a 2s lipo, and see how that works.
Oct 02, 2017, 01:00 PM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Going from 2S to 3S will nearly double the current so almost certainly will burn something out.
Oct 02, 2017, 01:18 PM
Heligamist
BrokeDad's Avatar
I would think the blades need to be matched together. They aren't in the picture. I had an old coaxial like that years ago. It flew a couple times and died. If you don't have the RTF radio for it then it probably won't fly with anything else.
Oct 02, 2017, 02:21 PM
Scratch Builder
TrooperCooper's Avatar
Oh... I thought they were supposed to be contrarotating rotors. This would almost certainly eliminate all of the excess torque, which was my reasoning. So my understanding is that they are supposed to be rotating in the same direction? This would certainly cause some vibration from my experience from fixed wings. Correct me if I am wrong.
Oct 02, 2017, 02:44 PM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
They rotate in opposite directions.. or at least they should! When viewed from above the upper rotor should rotate clockwise and the lower anti-clockwise.

It is important that the blades are match balanced. If they came in different sets then you would most likely have to balance them by adding tape to the light blade. The flybar must also be balanced, or at least accurately centred.
Oct 02, 2017, 04:28 PM
Scratch Builder
TrooperCooper's Avatar
Ok I will check that. Thanks!

EDIT
Just checked it out, and it looks to me like the blades are running correctly, but I have not tried balancing them yet. How would I go about doing that? I am used to working with two bladed props, not single bladed rotors.
Last edited by TrooperCooper; Oct 02, 2017 at 06:40 PM.
Oct 02, 2017, 11:54 PM
rc user
you might get more help in the beginner or coax forum.
Oct 05, 2017, 05:04 AM
Registered User
Atomic Skull's Avatar
Quote:
Originally Posted by TrooperCooper
Here is the heli. It has never been flown indoors, I am planning to switch it over to a 3s lipo rather than the 2s lion it came with. It is toy grade as well, so if it is in fact the brushings, then it will probably get scavenged for parts.
That's not what we consider to be a "large" helicopter. When we say "big" we mean something like this:

Align T-Rex 700x - Good Morning Flight :) (5 min 12 sec)
Last edited by Atomic Skull; Oct 05, 2017 at 05:10 AM.


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