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Old Jun 17, 2015, 06:28 AM
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First 450 size Heli set up advice

Hi All

Very much still quite a newbie so please bear with me!

I have moved up to my first 450 size Heli and want some advice in terms of getting her set up as some of it still seems a dark art to me

I had an MJX-F46 which was great fun - took me a while to get the hang of setting it up to get it super stable and even added a brushless motor which is great. Thing is with these setting up is relatively straight forward simply adjusting the trim and servo arms and I got it to be stable hovering etc

I have moved up to a 450 - CopterX 450 pro V4 which has a CX-3X1000 Flybarless unit fitted, Spektrum RX. Im actually using a DEVO 7E TX which Ive loaded with Deviation Firmware to give it the DSMX compatability and its all binded and working just fine. All servos seem to be behaving themselves and the flybarless unit set to Beginner mode.

That said when taking off at the moment the unit starts rotating or pulling left, or tilting and by no means set up well enough to simply apply throttle and go in to hover.

I do have training gear on though fortunately otherwise Im sure I would have damaged something by now!

Simply adjusting the trim on the controller does not seem as effective as with the MJX so Im guessing I need to manually enter the trim settings.

My question is where to start and how do I even know the blade angles etc are correct?

All advice appreciated to give me a starting point....my aim at the moment is simply to get stable take off, landing , hovering and basic movement.
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Old Jun 17, 2015, 12:45 PM
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I'm not familiar with that FBL unit at all, so I cannot give you any detailed advice as to HOW things are done. However, you have to get the heli set up mechanically correct, which means servo arms at 90 degrees at mid-stick using some form of sub trim (either in the transmitter or the FBL unit; that should be explained in the FBL unit's manual), then level the swash (gain either on FBL or TX), set the direction of the correction right (swash should try to stay level when you tilt the heli, instead of tilting in the same diretion as the heli), set the tail endpoint and correction direction, set the directions in the TX so a stick input results in the correct response direction,...
Before I continue with this list (which I'm doing from memory now, so it likely won't be complete anyway) - which of these items on the list have you done so far?
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Old Jun 17, 2015, 01:45 PM
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Just to clarify things, DO NOT use TX trim to try to correct any drifting to one side or the other. With the CX, just as with most if not all FBL controllers, you must use zero TX trim. As getsoyubi said, make sure the mechanical setup is right. There are trim adjustments for the servos in the CX software.

When a single rotor heli is hovering (with a clockwise main rotor) , it will necessarily lean to the right, and that's something you need to get used to when starting out.
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Old Jun 17, 2015, 01:56 PM
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when set up correctly you can till have to tap roterhead to level for launch .not saying youre even close to that yet.cx box does not need the fast pop heli into air bit
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Old Jun 17, 2015, 02:21 PM
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use cx program no tx trim for setup. first hop if you need like 4 click aileron trim on tx to avoid drift you can do that but then take heli in and transfer that trim from tx to the cx box or heli
depending on iflink needs slight ajustment or if servo is hair off bit
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Old Jun 18, 2015, 09:02 AM
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What I have done so far

So I linked the FBL unit to the PC and to start with set to Beginner which does 'stuff' and then followed the set up through. The part I need to concentrate on is the swashplate correction as that threw me a bit but I get the concept so Ill revisit that.

The other this that the me was the Servo Direction - how do I know what should be where - well I toyed around with that and came to the conclusion that the swash should simply move up and down with throttle so all looks ok.

One thing I am unsure of is that when I watch videos of people taking off they seem to be able to throttle up and then 'take off' as opposed to mine which tries to lift and then tilts when simply increasing throttle. Should I be able to control this and if so why cant I.

Probably horribly stupid questions but clearly its a big leap from a little 46 to a 450 and I really dont want to trash it straight away so Im being mega cautious!

Thanks for the help and advice
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Old Jun 18, 2015, 09:49 AM
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It's tough not having someone to help with new stuff, but I think you seem to be going about things in the right way - proceeding with caution!

Make sure that the CX is correcting everything in the right sense. When you move the sticks, the tail and swash should move the right way. I think you've already managed that. When you're sure about it, hold the heli and tilt it sideways and forwards/backwards, and verify that the swash tilts in a direction to oppose the movement. In effect, it should look like the swash stays level when you tilt the heli. Setting the correct Piro Opt direction is something many people have trouble with. When you click on the "Check Optimization Direction" button, the swash will tilt. With the heli on the bench, rotate the heli 90 degrees to one side or the other. The swash should stay tilted the same way, eg towards one end of the bench. To check the sense of the tail gyro, I find the easiest way is to rotate the heli to the right, whilst keeping a finger on the tail end of the tail control rod. If the tail gyro sense is correct, the rod should move to the rear, and I find it easier to feel that rather than to see it, especially on a 450 Pro where the tail servo arm is a bit hidden.

Do you have a sim? It could be that when you're trying to take off, you're feeding in a bit of aileron. If the CX hasn't been set up right, tho, it might be seeing some aileron input when your aileron stick is at neutral. If your training gear is really flexible, that can make things a bit trickier too.

Make sure in the "Monitor" tab of the software that you are seeing zeros for all servos with the sticks at neutral, and adjust your TX sub-trim to achieve that if you haven't already done so. You should see 100's at full stick deflection, and achieve that by adjusting your TX ATV's. Depending on your TX, you might see 30 points of sub-trim and several percentage points of ATV adjustment.

Go over the mechanical setup. Make sure all the servo arms are at 90 degrees to the servo body or linkage rod at neutral. In order to get 50% collective (zero pitch) more easily, I use a pitch curve for setting up that goes 0, 50,50, 50, 100. That way you don't have to position the collective stick with any precision to be sure you're at 50%. Beware, however - don't try flying with that pitch curve! (how do I know? )To make any adjustments, use Servo Trim in the CX software. Adjust the three servo to swash links to make sure the swash is dead level with the cyclic servos at neutral. If you need to make adjustments smaller than one turn of a linkage rod, go back to the "Servo Trim" tab in the software and make fine adjustments there. A swash levelling tool is handy for this, but you can also use a cable tie (zip tie) or if you've a good eye, judge it by eye.

The CX was my first FBL controller a few years back. When I first set it up in my HK 450 Pro, I was amazed at how stable the heli was on it's first flight in the "Beginner" settings.

Good luck!
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Old Jun 18, 2015, 12:59 PM
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http://www.rcgroups.com/forums/showthread.php?t=1512179

http://www.helifreak.com/showthread.php?t=485789

Good links
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Old Jun 19, 2015, 05:01 AM
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Hmmm so playing around a little and Im getting a better understanding now. All servos are at 90 degrees no and direction of everything seems fine and swash plate behaving as expected. I have also made adjustments to stop excess 'travel'.

So everything spins up just fine and I can now get the blades spinning up correctly to then allow lift....however its basically just pulling over to the left and I cant work out why.

Where else am I going wrong please?
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Old Jun 19, 2015, 07:00 AM
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What exactly do you mean by "pulling over to the left"? The tailrotor pushes the heli to the left; that's why in flight every RC heli leans to the right (full size helis usually lean to the left because most of them have a counter-clockwise rotating main rotor, so the tail pushes them to the right).
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Old Jun 19, 2015, 07:10 AM
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Quote:
Originally Posted by voipboy View Post
I can now get the blades spinning up correctly to then allow lift....however its basically just pulling over to the left and I cant work out why.
The pull to the left is called translational tendency and caused by the tail rotor. A good way to understand why and what is happening is to start from the ground. When your heli is sitting on the ground it is about 6 degrees off from its natural point of stability.

In a stable hover (hands off the controls and independent of trim) the heli leans about 6 degrees to the left. It is not moving to the left - it is stable. The question is how do you compensate for that 5 degrees? You can't do it with aileron trim because trim is a constant offset and when your heli lifts off the ground it will roll right and continue to roll right.

A slight nudge of RIGHT aileron is all you need for the heli to attain a vertical lift-off without any roll. The amount is critical and the timing is critical. As soon as the skids leaves the ground it is going to start rolling left to acquire stability. The split second nudge of right aileron will stop the heli from continuing that roll to the left. This split-second timing is one of the most crucial factors for a vertical lift off. Most beginners (and many non-beginners) lift off the ground not realizing the heli is unstable at that point and they are immediately trying to "correct" the error. Which often results in over-correcting and in a matter of seconds the heli is oscillating back and forth and you are chasing the heli or it is chasing you

A common practice is to jump the heli off the ground and gain altitude and then correct the error. While this method works - it takes away from the reality of a full-scale helicopter and instead of smooth and controlled transitions you are correcting error. For some - not all - the looks and the flight characteristics of a full-scale helicopter is part of the challenge of flying RC helicopters. Full-scale helicopters don't jump off the ground - they lift so gradually it is difficult to discern when the skids leave the ground. Emulating that with an RC helicopter can make your hair stand on end.

Good luck with your 450. Simulator time can reduce the number of crashes substantially and give you the hours of stick time you need to develop muscle memory. When you can only fly 5 minutes at a time - and most of the time is waiting for parts - it takes a LOT longer for that muscle memory to develop. The introduction in Don't Touch the Controls thread details a method to minimize over-controlling and has helped many beginners. Recommend getting some help - learning on your own is like teaching yourself golf - you can hit the ball - it just never goes where you want it to. Have a great training - and most of all FLY SAFELY and COURTEOUSLY.

captJac
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Last edited by CaptJac; Jun 19, 2015 at 09:06 AM. Reason: Don't Touch the Controls
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Old Jun 19, 2015, 07:58 AM
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Voipboy - can you post a video showing this left pull?
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Old Jun 19, 2015, 10:06 AM
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.....so to be clear here - and yes Ill try take some vid but as yet this this has not even yet left the ground!

When I apply the throttle only it starts to hop and skip about left and right and then any attempt to lift sees the heli pull all directions but generally either starts to dig in the tail to the ground or seems to become very unstable and try to roll or pull to one side.

Clearly I have something set up very very wrong as there is no way in hell I could hover hands off - in fact to get to that point would be a joy!

I dont know where to start now - the logic all seems relatively straight forward and Im pretty sure everything is going the direction it should (clearly not!)

Fortunately I have skid on otherwise Id certainly have been waiting for parts by now!
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Old Jun 19, 2015, 11:13 AM
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....waiting for parts now lol I thought it was maybe me just not giving it enough juice to help it lift but seems not as it simply dug the tail down and span. Think at this rate it will end up on ebay
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Old Jun 19, 2015, 11:25 AM
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Vibes!

Most likely cause of those symptoms would be high vibes, even though the 3x1000 is more resistant to vibes than, say, a Kbar. Try to use a good blade balancer for the main and tail blades. On my 450's, I like to use a small magnetic one, seems to be more accurate than the seesaw type. I use 3M Scotch "Magic" clear tape for balancing.



Also make sure there is no endfloat in the feathering spindle, and that the main grips look equally spaced either side of the hub. It's not uncommon for clone helis to be mis-assembled at the factory.
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