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May 21, 2019, 03:20 AM
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Building my first 450 heli, kbar issues


Hello all. I've been building a 450 clone based off the align 450 pro. The orginal head was a pain to set up and the 3 gyros that I ordered kept getting lost in transit so I decided to go fbl with a mini k-bar. The kbar showed up last week and the new ridgid fbl head showed up yesterday so I started rerunning the wires. Finally got it figured out. Downloaded the software for the kbar and started working my way through the settings. Got to the rudder and none of the settings are working right. The servo is very glitchy and doesnt want to accept the commands from the tx. I'm using a radiolink with a r9ds reciever. The tail servo is a cheap Amazon servo. A sg92r. It was nice and smooth before I wired the kbar in. Did I miss something in the settings? Or do I need to spend the extra money for a higher quality servo. This is my first real rc helicopter so it will just be light flying around the park until I get more comfortable with the controls.
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May 21, 2019, 01:37 PM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
There are a few different servo the tail servo setup, for the budget servo you are using the choice which starts with '2700G' would be best.

For sure though a better tail servo would be a good isea. The speed of that servo is too slow for a tail servo and the plastic gears will be easy to damage. A specialised heli tail servo would be much better.
May 21, 2019, 06:42 PM
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Thank you for your reply. I got the gain set alittle better and its moving better but still not as smooth as I would like. I just ordered an Apex 6600g. Specs are .09sec to 60* at 4.8V. My esc has a bec with a 5.2v. It also runs at 1520us/330hz which is one of the settings in the program so hopefully that will help. Only downside is it's a full size servo and it mounts on the tail boom so it will stick out. I've been slowly building it up for about 4 months and I'm about ready to take it for a test flight.
May 23, 2019, 08:25 PM
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Got the new servo in, then I checked the balance of the blades and they are perfect. Remeasured blade pitch and I have it set at -4 to 12* I get it up to 30-40% throttle where it's getting light on the skids. Then it will start to shake and it tips over. Not sure what else I can check
May 24, 2019, 02:26 PM
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rhodesengr's Avatar
kbar doesn't get much love. Think about a controller that tired and true. ICON or Spirit are both reasonable in price and full featured (Rescue, vibration analysis, software setup, wireless possible, no extra firmware required, etc.)
May 24, 2019, 03:30 PM
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I'm just getting into the hobby and funds are tight. I did find that I had the wrong type of servos selected in the kbar software. I'm running analog and I had digital selected. Also one of the blade was loose where it connects to the service link. That solved a good bit of the vibration but not all of it. Took the tail boom off to inspect the shaft and it was slightly bend so need to find a replacement for that.
May 24, 2019, 04:49 PM
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rhodesengr's Avatar
Quote:
Originally Posted by Smokeshow32
I'm just getting into the hobby and funds are tight. I did find that I had the wrong type of servos selected in the kbar software. I'm running analog and I had digital selected. Also one of the blade was loose where it connects to the service link. That solved a good bit of the vibration but not all of it. Took the tail boom off to inspect the shaft and it was slightly bend so need to find a replacement for that.
well we all have to follow our own path but a decent controller is the key to success. Think about it this way.... if the model tips due to vibration sensitivity and get wrecked then it will cost you time and money to repair. I use Spirit because it has reliable Rescue.

But if you are truly just getting into the hobby, the conventional wisdom is to start with micros. I have the Align 150X and it works better than any Blade micro I have owned. People say good things about the Blade 230S though. On the less expensive side, I see people say good things about XK K110 which is only $90 RTF.

If you want to save money on a hobby grade 450, then it might be a better idea to buy a used one with decent electronics. Look for Oxy's or an Align 450. Look here on RCG or over on Helifreak.
May 24, 2019, 05:57 PM
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Thanks. I have discovered that it would have been much cheaper to buy a complete kit instead of a clone shell and adding everything individually. For a tx I'm using a radiolink at9s.
But to me it is a good learning experience. Eventually I'll upgrade everything as I go. Probably start with all new servos, then a better gyro. I had played around with the palm sized dual blade helicopters. Nothing fancy though. I have several nitro cars and trucks. But this is my first larder scale heli.
May 24, 2019, 06:17 PM
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rhodesengr's Avatar
Quote:
Originally Posted by Smokeshow32
I had played around with the palm sized dual blade helicopters. .
So you've never flown a collective pitch heli? It is very different from a coax unless you have a controller than simulates a coax mode (like Spirit does).

You really should start with a micro. I already mentioned the K110. That is one that gets good press even though cheap.
May 25, 2019, 01:39 AM
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Cyclone 7's Avatar
I really do think that you should follow rhodesengr's advice and consider starting over with the K110 as a good, affordable introduction to CP helicopters. From what I understand, it is virtually indestructible and cheap to maintain - just what you need to get you off the ground initially.
May 26, 2019, 06:17 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
The Kbar usually works fine, I used to use them a lot when i started out.

A full size servo is far too big for a 450, it will make the heli tail heavy. It's also too slow, for a tail servo you should be looking at something 0.05S or faster. You need to look as a micro or mini size servos.

By trying to buy super cheap you usually end up spending more due to having to replace all the cheap junk and fix the heli after the crashes caused by it. This is not to imply that you have to pay a fortune for the very best 'boutique' brand names, but there is a 'happy medium' where you get good performance and reliability at a reasonable cost. Something like the KST DS215MG is a good all round micro size servo that works well on the swash or on the tail.


If the heli is tipping then most likely you have the gyro compensation or Tx response reversed. it's really important to check for correct response of the swash and tail to both tx input and to movement of the heli.. Check and double check.
May 26, 2019, 09:19 AM
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Thanks for the reply. I was actually looking at the kst servos for when I do upgrade. I've checked the for the proper swash movement for both the stick controls and by tilting the heli and the swash moves in the correct manner. Once I get the new tail shaft in I'll see if it keeps trying to tip over and go from there. But I'm getting ready for a cross country move in about 3 months so most of it will have to wait until after I settle into my new place.
May 26, 2019, 12:41 PM
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rhodesengr's Avatar
Quote:
Originally Posted by JetPlaneFlyer
If the heli is tipping then most likely you have the gyro compensation or Tx response reversed.
Usually, if the tail control or feedback directions are backwards, the heli will spin as you spool up. Common sense would suggest that tipping is due to something in the cyclic but vibration at the tail frequency can cause tipping. It may depend on the FC (flight controller) but was definitely true of BeastX.

My first 450 (which I still have and fly with Spirit now) was a Blade 450 3D converted to FBL with a Tarot head and an AR7200. On a particular flight I had to do a hard save and that triggered a few seconds of intense tail wag. There was no crash. On the next flight, the model started to tip immediately as I lifted off. Turned out the tail blade grips were slightly bent so the blades were not perfectly lined up. The high speed wag was all it took to slightly bend the tail. I replaced the tail parts including the shaft and the tipping was gone.

Tail movement direction can be confusing. It is hard to tell just by looking what is going on. This video is super helpful for checking your tail control and feedback.
How to: Check gyro and tail compensation on RC Helis (1 min 26 sec)

The cyclic is less confusing because left stick goes left and stick forward tilts the swash forward. Feedback just opposes motion so it you tilt left, the swash should tilt to the right. Tilt forward and the swash should tilt to the back.
May 26, 2019, 03:52 PM
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Thanks for posting the vedio. Mine is set up correctly as left rudder the tail blast go left and right goes right. And I can manually move the tail left-right and the tail blades move in the correct direction. I have the new tail parts ordered. Should have it be next weekend and will post results once I get them back installed. Aslo just recieved the USB training cable for my radiolink tx so going to try and download a few demo sims and try them out.
May 26, 2019, 08:41 PM
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Tried downloading the clear view demo simulator but it wont let me open it. Says it cant find the file on my drive. Got the demo for Heli-x installed and was doing the first run when my 2 year old spilt some water on my laptop and pretty sure its fried now.


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