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Old Jan 26, 2013, 02:54 PM
Registered User
United Kingdom, England, Bradley Stoke
Joined Mar 2001
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Hk450 first flight

Hi all,

I r entry bought a used HK450, the seller told me he had trouble setting up the gyro and it had barely left the ground which appears to be true looking over it.

I've been hovering it a bit and getting it setup properly and it appeared to be fin but today I too, it for its first FFF and I noticed 2 things.

Firstly, in FFF the tail began to wag. To correct I turned down the gain a little and it appeared to resolve.

Secondly, I noticed the appeared to be a lack of tail authority. Stall turning didn't seem to move the heli much and was a bit of a struggle. Has anyone else noticed this kind of reaction on the hk450?

This is the first time I've had a heli in FFF since march 2012 so I am a little out of touch, prahaps it's me? But it did seem less responsive than expected.

Ryan
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Old Jan 26, 2013, 08:53 PM
Registered User
Australia, VIC
Joined Dec 2011
1,108 Posts
Hmmmm

Quote:
Originally Posted by bulldog5046 View Post
Hi all,

I r entry bought a used HK450, the seller told me he had trouble setting up the gyro and it had barely left the ground which appears to be true looking over it.

I've been hovering it a bit and getting it setup properly and it appeared to be fin but today I too, it for its first FFF and I noticed 2 things.

Firstly, in FFF the tail began to wag. To correct I turned down the gain a little and it appeared to resolve.

Secondly, I noticed the appeared to be a lack of tail authority. Stall turning didn't seem to move the heli much and was a bit of a struggle. Has anyone else noticed this kind of reaction on the hk450?

This is the first time I've had a heli in FFF since march 2012 so I am a little out of touch, prahaps it's me? But it did seem less responsive than expected.

Ryan
Its not the heli

2 possibilities - Tx settings and Gyro ..

So you have asked a question - offering very little in detail ... expecting an answer ?

So lets fill in the spaces .. What radio ? What Gyro ?

What has been done ? in the ways of settings ?

Have end points been set VIA Tx , what of the gyro settings ..

DR/Expo ?

Im sorry , but with all the variables ...

Cheapest Trex 450 helicopter clone HH gyro setup 14 (9 min 49 sec)


Horizonhobby.com How To - Setup your Head Lock Gyro the easy way (6 min 9 sec)


Setting up the GA250 Gyro (10 min 53 sec)


Setting up Spartan Quark gyro (4 min 43 sec)


Colco GY400 gyro set up (Futaba GY401 look a like) (4 min 33 sec)


Horizonhobby.com How To - Setup your Head Lock Gyro the easy way (6 min 9 sec)
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Old Jan 26, 2013, 10:49 PM
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jasmine2501's Avatar
United States, AZ, Mesa
Joined Jul 2007
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Usually high gain and slow turning indicated you used too short of a servo arm. If you can increase the length of the servo arm without binding, try that. Be sure to lower the gain and do the setup again.
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Old Jan 27, 2013, 04:57 AM
Registered User
United Kingdom, England, Bradley Stoke
Joined Mar 2001
81 Posts
Sorry, autocorrect and a few beers are a terrible combination for forum posts.

It's an Esky Tx/Rx, hk401b gyro with around 25-30% gain in HH.

The control arm is in the middle peg on the servo horn, full movement of the tail is available in rate, I reset the limits when I got it as it wasn't using the full range.

Not sure if it makes much difference but it appears the tail may have been changed for an align unit, only 1 part has align written on it though so I can't be sure...

I wondered if I might have my hover pitch set too low as when bringing it down the tail did seem to be losing control. I turned it down as the wing seems to have less of an impact on a lower head speed.
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Old Jan 27, 2013, 06:16 AM
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Australia, VIC
Joined Dec 2011
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Wow ok the HK401B [ what a fun gyro ]

Hmmm , 25 to 30% gain could be the cause for your lack of Authority ...

You could try rate mode , and see how that goes if you cant dial in enough gain without getting wag in HH mode .

I have a HK401B and another 401B and I have to admit to defeat [ so far ] in HH mode
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Old Jan 27, 2013, 07:14 AM
Frank
Germany, BW, Heubach
Joined Dec 2012
928 Posts
Hey old,

I have your 450 build writeup, man did it help me, just wanted to say thanks Dude.
Setting up the rotorhead was a challenge, but with your help, made it a simple task.
Heres a pic of the not yet finished heli. A flymentor is going to be used on this heli as I am moving from fp to cp, Kind of Insurance for the first time

Oh btw. this is my first 450 heli build.

Frank
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Old Jan 27, 2013, 07:57 AM
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Quote:
Originally Posted by old4570 View Post
Wow ok the HK401B [ what a fun gyro ]

Hmmm , 25 to 30% gain could be the cause for your lack of Authority ...

You could try rate mode , and see how that goes if you cant dial in enough gain without getting wag in HH mode .

I have a HK401B and another 401B and I have to admit to defeat [ so far ] in HH mode
Willing to give it a try but I've never flown in rate mode before. What do I need to be aware of for the way the heli will fly? I presume I will need to put more manual control in?
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Old Jan 27, 2013, 08:04 AM
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Australia, VIC
Joined Dec 2011
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Wow thats looking good

Quote:
Originally Posted by R.C. Man View Post
Hey old,

I have your 450 build writeup, man did it help me, just wanted to say thanks Dude.
Setting up the rotorhead was a challenge, but with your help, made it a simple task.
Heres a pic of the not yet finished heli. A flymentor is going to be used on this heli as I am moving from fp to cp, Kind of Insurance for the first time

Oh btw. this is my first 450 heli build.

Frank
That's looking really nice R.C. Man , keep us posted on the build ...

The PDF helped , nice [ thanks for letting me know ]
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Old Jan 27, 2013, 08:15 AM
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Joined Dec 2011
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Rate Mode

Quote:
Originally Posted by bulldog5046 View Post
Willing to give it a try but I've never flown in rate mode before. What do I need to be aware of for the way the heli will fly? I presume I will need to put more manual control in?
Increase gain to 100% , waging should go away around 70% gain or so as you sort out the gain level in rate mode

Rate mode holds the tail , but not as well as HH mode [ all things being equal ]
In rate mode , over time , there may be more drift , and if the wind hits it and pushes it [ tail ] it will resist , but not return to where it was before the push [ wind ] , but if HH is giving issue , then rate mode may be better than a lousy HH mode . [ Lesser of two evils ]

If your in the market , the Detrum GY48V might be the best sub $20 gyro thats not a mems gyro . Maybe ? I dont know of a better one yet .
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Old Jan 27, 2013, 11:35 AM
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United States, AZ, Mesa
Joined Jul 2007
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This isn't a 450 problem, it's a gyro issue... here's a few things that can go wrong with them, and these things only apply AFTER you verify the stuff is working correctly and there's no binding.

1. Tail won't hold even with lots of gain - servo arm too short, head speed too low
2. Tail won't stop wagging even with low gain - servo arm too long
3. Tail turns slowly but otherwise holds good with no wag - Servo arm too short, gain too high
4. Tail turns quickly and feels loose, like it wants to let go - servo arm too long, gain too low

Also keep in mind, you can't tell the behavior of a heading hold gyro unless the machine is in flight at a high enough rotor speed. The feedback (actual motion) isn't correct unless the helicopter is free flying in the air, so the gyro will do funny things. This makes it impossible to do a good visual inspection of the behavior - the only way to know what's happening with a gyro is to fly it.
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Old Jan 27, 2013, 04:37 PM
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United States, SC, Irmo
Joined Sep 2011
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Great videos. I am also suffering with the HK401B. I am about to throw it in the garbage. It is not letting my servo move smoothly and quickly when hooked up to it. I watched some of the videos above. So to confirm it IS typical to have a few degrees of positive pitch on mechanical setup? The HH video said to center it.

So I set up in rate mode first before going to HH mode, right?

And another point of confusion. I was setting limits in my radio, but one of the videos showed using the limit on the gyro and this will also protect the radio from overdriving the servo as well as the gyro, is this correct? So I should leave the limits on my radio to max?
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Old Jan 27, 2013, 05:09 PM
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United States, AZ, Mesa
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Quote:
Originally Posted by shahram72 View Post
Great videos. I am also suffering with the HK401B. I am about to throw it in the garbage. It is not letting my servo move smoothly and quickly when hooked up to it. I watched some of the videos above. So to confirm it IS typical to have a few degrees of positive pitch on mechanical setup? The HH video said to center it.

So I set up in rate mode first before going to HH mode, right?

And another point of confusion. I was setting limits in my radio, but one of the videos showed using the limit on the gyro and this will also protect the radio from overdriving the servo as well as the gyro, is this correct? So I should leave the limits on my radio to max?
You center the slider, not the blades. Your helicopter has a little bit of thrust in the blades with the slider centered. This is so that the maximum piro rate is approximately the same in both directions - against the torque, and with it. It also sits at approximately the right place for tail holding, with the slider centered. So, center the servo and the slider together, then use the limit setting on the gyro to limit the slider travel so it doesn't bind but goes as far as possible.

Adjusting the limits in your radio for the rudder channel does not limit the servo travel. Remember, the gyro is controlling the servo, and it decides how far to send the servo to respond to your commands. So, reducing the travel in your radio reduces the amount of piro speed you can request, but it doesn't change the servo travel. This is important to keep in mind because if the gyro is capable of binding the servo (driving it too far) then that could happen in flight, potentially damaging the servo, regardless of the travel settings in your radio. The only way to limit the slider travel is to mechanically adjust the servo arm, or adjust the limit on the gyro itself.
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Old Jan 27, 2013, 05:51 PM
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OK, I think I understand it a lot better. I think I just need to junk this garbage gyro. It's a shame, I see lots of people use them with no problems. I got mine working great on the work table but on spoolup it goes wacky.
HK401B still not working (0 min 0 sec)
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Old Jan 27, 2013, 06:19 PM
WOS
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Check end points?
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Old Jan 27, 2013, 06:34 PM
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Joined Sep 2011
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They are back to 100 since I adjusted them on the gyro. Actually I think they are about 70. I was trying to find a setting to maximize stick resolution. This also included moving the link ball in two holes. The slider moves fully left and right so it's not endpoints. This gyro goes in the trash tomorrow morning. I wonder if to try my other one, the Futaba one, or maybe order another ZD720 from China. Heck, I even have a Flymentor in the box.
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