Hi Everyone,

Finally I have completed build of HK-250GT Heli with following electronics

1. HK-250GT Kit
2. Turnigy 3500rpm Motor
(http://www.hobbyking.com/hobbyking/store/__14741__Turnigy_L2508A_3500_Brushless_Heli_Motor_200w_.html)
3. 40 AMP ESC
4. 4 x HXT-900 Servos
5. Turnigy Nano-Tech 3S 1000mAh Battery
6. HK Gyro
http://www.hobbyking.com/hobbyking/store/__10113__Hobby_King_401B_AVCS_Digital_Head_Lock_Gyro_.html
7. Turnigy Tx Rx

Due to busy schedule, I didn't click building Pic  , I build it in 2 Days, So Problems are expected for me (as a beginner)
1st Day - Electronics Connections
2nd Day - Building Heli


I read building blogs and videos, and found Thread-lock is required (Blue)
So I order it, also Align Belt and feathershaft ( not yet received, waiting for shipment)

Pinion is stock one = 15T (waiting for shipment of 11T and 12T pinion)

Applied Thread-lock mostly places where screw is going in metal.


Problem Part is also coming

Hi Bisht G,

You have done a fair job of assembling the heli, considering you are new to them. Just wanted to ask you, what is the 'problem part' you referred to? and if it is the feathering shaft, what difference would the Align shaft make? Thanks,

Cheers,
Amit K

Hi,

Dont know what Align Feather Shaft will do, but I buy because all blog says, any ways. this is not the issue, because now Feather shaft is tight with thread-lock, So I hope it will not come out,

Problem 1
Swash Plate is not parallel to Blade/Flybar, as it should be
and now more space available on link age rods....

and when I checked with Pitch Gauge it showing me my normal pitch is -4 deg

Problem 2
Gyro, not able to figure out its setting, also have Turnigy 9x Tx Rx so it have Gyro option,
so I configured UPGyro = 40 and DNGyro =60
Still searching how to put in Head Hold mode

Also observed my heli Main Rotor Head do humming when I turn it in low speed, and complete heli is shaking....

Gyro is giving problem when I m putting more throttle then my heli tail is waging

Some humming sound is okay in slow rpms, however, you may still want to be sure that the pinion is not too tight against the main gear. Also, the shaking of the heli could be a result of the main blades too tight in the blade grips. The tail wag usually points towards a 'higher than required' gain setting for the gyro.

Hope these things help you solve the issues, 

Cheers,
Amit K

ok, Pinion is ok and now to tght, its body is humming not humming sound,
main blades are not to tight also,

How to reduce Gain in mention Gyro ?? using Turning 9X
Rudder Input Connector is in Ch-4
Gyro Sensitivity Input Connector is in 5-Ch

Also face very strange thing, When I give throttal it turn complete head, but If i stop motor motor stop but still only head rotate and stop slowly,

When I connect wrong motor cable it turn motor in Opt. direction, and in this situation head not rotate only main gear and tail rotate

Uploading video...and providing  link......

Quote from: gbisht on May 06, 2012, 11:39:47 PM
Also observed my heli Main Rotor Head do humming when I turn it in low speed, and complete heli is shaking....

Gyro is giving problem when I m putting more throttle then my heli tail is waging

1.do not tight the main blades
2.yes it shakes in low rpm
3. gyro settings

do this ( went good with me , may be little bit adjustment in your case)

Go to gyro menu and change the mode to GY.
Set the Downrate to AVC 40
Set the Uprate to NOR 40
Toggle the GEAR switch. The light on the gyro should stay on in one position, and go off in the other position. If the light is on when the gear switch is towards you, go to reversing menu and reverse channel 5.

Downrate: AVC 40 is the heading hold gain. Increase or decrease if required. Somewhere between 30 and 45 would be a reasonable number.


or this


http://www.rcindia.org/helis/tail-wag-on-hk-250/



and the first thing is you have not done yet , make a gyro testing table in home, like this




and let us know

Hi Vineet,

Thanks, I done according and now on up LED is solid,
UPRATE  NOR  040
DNRATE  AVC  040
MODEL   GY

Do I still need to Reverse ch-5 ?

Also Heli rotation and tail wage  Problem

Vineet Still on high speed tail wag, same as video

Hi Gaurav,

you need to  balance your blades it will take care of the wobbling affect/ heli shaking affect,  spining of head at the end is normal which happens due to the autorotation gear in the heli so don't worry about that and keep the motor connections as is.
Your connections for the rudder servo and Gyro senstivity are fine, Your Turnigy transmitter Owners manual should explain how to change Gyro settings on the Transmitter, also make sure that the Gyro Direction switch on the HK401B Gyro is in the correct direction.

Also make sure that the DS (Digital ) switch on the Gyro is turned off as you are using HXT900 servo on the Tail which is a Analogue servo.

Let me know at what throttle stick position are you getting -4degrees pitch and let's sort that issue as well.

Hellyflyer

Hi Amit,

Balance Blades : By shorten or increase length of Linkage in Rotor Head ??
Auto rotation : May be because its main gear have one side rotation bearing ?

But didn't get following 2 points:

Point-1 keep the motor connections as is.Your connections for the rudder servo and Gyro senstivity are fine -
Point-2 There is no Direction switch in Gyro

DS is off

Yes the main gear has one way bearing that's why, you are spot on :-)

What you didn't get

1. Keeping the motor connections as is  means don't change the direction of the motor  because of one way bearing leave it as is.

2. If you remove the small covering from the DS switch and look carefully you will see 2 micro switchs side by side the Direction switch is right next to the DS switch.


I saw the video just now , your blades look balanced so no need to balance your blades, the tail wag is only due to High Gyro Gain coming from the Transmitter, search on the thread below , this should hopefully solve your issue of finding correct settings for this Gyro.

http://www.rcgroups.com/forums/showthread.php?t=1347721

Ok got it that is labeled with DR

So how I know that is in correct ??
Right now it is on NOR Side

Refer the link for pic
https://www.hobbyking.com/hobbyking/forum/forum_posts.asp?TID=9340

Looking at the video, the Heli's tail is just wagging and not spining so I presume it's in the correct direction, you may keep it at the NOR side. The Heli would spin rapidly if the direction is changed.

Quote from: gbisht on May 07, 2012, 12:37:51 AM
Also Heli rotation and tail wage  Problem

careful man you will cut your bed sheet,

yet it  is just a problem with the gyro adjust the gain ,that's it.

I am in complete agreement with what Vineet said, it is a 'Gain' issue with the gyro. Keep going down on the percentage of gain, 1 to 2 percent at a time and keep checking for the wag to go away.

Cheers,

Amit K

Hi Thanks Vineet n all

Yes I reduced both gain one by one and now tail is now waging, but not fly because of time
and this time no on bed......(so bed sheet is out of danger)

Following GYRO settings adapted
---------------------------------
UPRATE  NOR  060
DNRATE  AVC  025
MODEL   GY

But how to identify optimum setting ??

another issue, when i m giving any movement to tail specially on right side, heli start slow spinning in right direction

[I can be believe that its flybar/blade/swash plate is balance..........on first time.......wow)

Can experts give suggestion on swash plate,

Few points may be wrong, plz verify

1. On Pic, throttle is 0%.
2. In 0% Throttle I am getting -4 Deg Pitch
3. I am getting neutral pitch around between 30% - 35% throttle.

For starters, it would be a good idea, to ensure, on '0' throttle you have a -1 kind of pitch, otherwise, during learning you may end up suddenly reducing the throttle, and would hit the heli on the ground way to hard. Around the mid-stick, the pitch should be around +3, these are just ball-park figure for basic comfort, you may need to tweak them as you progress.

The idea is to have a complimenting pitch to throttle curve, as too much pitch may bog down the motor if you have a low throttle curve, or with low pitch you may be revving unncessarily.

Hope this helps.

Cheers,
Amit K

Thanks Amit,

I got your point, so what method you suggest to reduce its pitch ?

1. Adjustment in linkage on Head (linkage between swash plate and Rotor Head/Blade Holder)
2. Reduce length of Linkages which are connected to servo (all 3 )
    which also reduce swash plate height on main shaft rod.

As you can see in above pic, on 0% throttle swash plate is still up (not completely down.

What is setting for 3D and normal Flight ??

I think
Normal Flight
===========
0% throttle => Pitch => -1 or -2 deg
30% Throttle => Pitch =>  +2 or +3 deg

3D  Flight
========
0% Throttle => Pitch =>    (-8 to -10) Deg
50% Throttle => pitch =  0 Deg
100% Throttle=> Pitch =  (+8 to +10) Deg

Please correct me and suggest me.....

Thanks
Gaurav

Quote from: akumar40 on May 07, 2012, 01:23:09 PM
The idea is to have a complimenting pitch to throttle curve, as too much pitch may bog down the motor if you have a low throttle curve, or with low pitch you may be revving unncessarily.

point

Hi Gaurav
The HK 250 is a twitchy bird. You will have to set up correctly right from the start. I think you mentioned that your swash plate is not level. The swash MUST be level at all points of the throttle stick movement. Please see Bob Finless videos on the Align 250 build and set up http://www.helifreak.com/showthread.php?t=109075&highlight=align+250. Unfortunately the 250 blade adjustments are more limited than the larger helis due to the use of unadjustable plastic linkage rods at the top. So one has to be doubly careful during set-up. Make sure your servo arms are lined up straight to start with. Then with linear throttle and pitch curves from 0 to 100 make sure that swash plate, washout control arm and flybar control arm are parallel and level right through the throttle/collective range. At centre stick, your pitch should read 0*. At full low stick anywhere between -9 to -12* and at full up , between +9 to +12*. Once you have got this correct, you can adjust your pitch curve to suit your flying. 40 - 45 - 50 -75 - 100 is a suggested beginners curve that should give you approx -2 to +10* pitch. I have been using 40 - 55 - 65 - 75 - 90. But this is all trial and error. My guess is that a beginner like me never uses more than 8* of pitch.
Then the 250 has an inherrent tail wag problem that most flyers have not been able to get rid of. There are pages written about chinese weights and all the other stuff. Well its just lucky if you get rid of it. Most have learnt to live with a bit of wag. I got rid of mine by reducing my belt tension. But I was lucky.
Please set up your bird carefully with the help of the Finless videos and it will save you a lot of grief.
I am only a beginner like you. So do wait for some more experienced flyers to comment on the above to check if my advice is correct or not.

Quote from: pradeepdasgupta on May 07, 2012, 04:57:07 PM
Please set up your bird carefully with the help of the Finless videos and it will save you a lot of grief.
I am only a beginner like you. So do wait for some more experienced flyers to comment on the above to check if my advice is correct or not.

beginner ??,does not seems like

Hi All,

After very long wait, Today I decide to fly this bird,

Flying:
======
When Heli left ground, it start spinning slowly in clock wise direction, So I used Sub-Trims to control it
But Hardly able to ride on issue.
When I sub-trim it start rotate in anti clock wise direction and was unable  stopped in middle, but it slow down some time
After Crash I found the root cause of this problem, and that was lose screw on tail blade holder (Probably, Find pic for screw, it is loosed more for pic)

But I dint stopped and fly it, then it CRASHED  , not actually my fault but due to Electronics Item Fail
(I bought Used Turnigy 9x few months back, and found Tx Rx connection break some time due to lose connection between Tx Module and Tx
I also applied cello tape both side of Tx Module but I think on flight time it didn't work)
Result: Heli start rotation and didn't stopped by Tx  , to stop it I used by foot and put my shoes on center of blade and finally stopped it  ,
I have to stop because few children's were playing on same ground only 2, Safety is first )

Crash Report
----------------
Broke/lost its
1. Tail Boom
2. Tail Linkage Rod Fin Band
3. 1 x Canopy Spinners
4. 1 x Tail Support Rod
5. Main Gear


Now On HK most parts are Back-order, so what you suggest guys should I buy complete HK-250GT Kit or wait for arrival of these parts ?