Heli spins hard on takeoff

garfro · 07-15-2007, 12:41 AM

I have 450sa and am just about hovering but the last few times i have taken it out to practice it gets a few inches off the ground and starts spinning (cant remember left or right) 1st time the belt looked slack so tightened and it still does it ......took it apart and looked for broken teeth and belt wear but can see none, tail rotor seems to spin up ok

Ant ideas????
G

ken6881 · 07-15-2007, 12:45 AM

after your in the air dose it still do it. if not before you take off putt a little right rudder into it and it will stop it. my se v2 was doing the same thing at the first time youd take off on a new pack so i took off then landed measured the tail pitch then set the center of the servo at that.

Skiddz · 07-15-2007, 12:49 AM

More than likely, you've got the gyro working backwards. I strongly suggest you checkout Finless's gyro video HERE
and pay particular attention to the final direction checks towards the end. Almost everyone who mentions this issue has the gyro direction reversed and has neglected to verify the proper operation of the gyro prior to spooling up the heli.

Good luck!

Brent@paradise · 07-15-2007, 12:55 AM

Do you use to be ablle to hover ok, whit out this problem?
if so what changed? di you replace some stuff?

what gyro have you got?
Are the tail blades spining the correct way, are they on the correct way.

garfro · 07-15-2007, 12:57 AM

Quote:

Originally Posted by Skiddz

More than likely, you've got the gyro working backwards. I strongly suggest you checkout Finless's gyro video HERE
and pay particular attention to the final direction checks towards the end. Almost everyone who mentions this issue has the gyro direction reversed and has neglected to verify the proper operation of the gyro prior to spooling up the heli.

Good luck!

I was thinking that myself.........after checking the mechanical side Ithought it must be in the electrics.....funny it was ok before

G

garfro · 07-15-2007, 01:00 AM

Quote:

Originally Posted by Brent@paradise

Do you use to be ablle to hover ok, whit out this problem?
if so what changed? di you replace some stuff?

what gyro have you got?
Are the tail blades spining the correct way, are they on the correct way.

Yeah it flew (well hovered) before then one time i took it out and the problem started

keep it up guys we will fix this together

G

Skiddz · 07-15-2007, 01:01 AM

So, you've been able to hover this thing before?? Or at least spool it up? Did the skids ever leave the ground before without it spinning? What kind of surface are you flying from?

garfro · 07-15-2007, 01:06 AM

Quote:

Originally Posted by Skiddz

So, you've been able to hover this thing before?? Or at least spool it up? Did the skids ever leave the ground before without it spinning? What kind of surface are you flying from?

It has hovered before and i have been hovering over grass that is maybe a bit too long and then one day it just started doing this and i am doing the obvios things to rectify but with no results

G

Skiddz · 07-15-2007, 01:11 AM

Grass has a LOT of surface friction and I was thinking you'd never actually got the skids clear of the grass and therefor never seen the spinning problem...

I'd certainly take a good look at the gyro setup and make sure you've got everything centered up mechanically (gyro in rate mode - or even better - completely out of the loop) and make sure the gyro initializes in HH mode *AND* is operating the proper direction..

Which gyro/servo are you running?

garfro · 07-15-2007, 01:15 AM

the gyro is a GY401 with JR 3400 digital .....I am going to check the gyro but like i said it was ok before then started doing it ..no repairs/crashes etc

G

Big Fil · 07-15-2007, 03:45 AM

reverse the gro direction

nwtampaguy34 · 07-15-2007, 03:32 PM

check the gear that holds your tail belt on inside the block. if it is plastic it could be starting to frey off the top part that holds the belt on. mine started doin the same thing one day and just looking from above while the heli was spinning up i could see it shaking a bit. then i discovered it was just about to break and of course i have the metal gear one now and no prob since. if u allready have the metal belt gear then i guess this wont help you. I am shure you will figure it out with all us frieks on here

jeffk · 07-15-2007, 04:21 PM

I'm wondering if you haven't got some binding in the tail rotor control rod, pitch slider, or perhaps the tail servo itself isn't working. Just because the tail rotor spins up doesn't mean that it's working properly.

Check your linkage and tail pitch slider for proper operation.

Pinecone · 07-16-2007, 06:42 AM

If you changed the belt, did you check to make sure you twisted it hte right way the tail blades are turning the correect direction (front blade turns UP intothe rotor wash)?

metsurf · 07-16-2007, 03:16 PM

I have just had the exact same situation as nwtampaguy34,- the gear didn't follow the shaft when the RPM's increased. I tried to CA it on the shaft and it worked fine, but I have now ordered the HS1216 for replacement. It seems that plastic parts in this position is unreliable.

I was hard to tell because at low speed it all looked okay, but immediately at takeoff it began spinning left.

_____________________

Steen

double0757 · 07-16-2007, 04:52 PM

Garfro:
I had something similar happen. When I was learning I hover one morning didn't do anything to the heli that afternoon it did what is happening to you. Suggestion. spool it up on cement or tile, put left and right rudder to see if it respond. then take it out side and see if it does it when you take it airborne. If you have a good rudder and goes out of control piro of the ground then is the Gyro reversing switch on the gyro it self. Can't explain why but it happen to me.
Double O

NINJA RICK · 07-16-2007, 11:56 PM

I have now seen three new 450sa with the slipping tail belt drive gear

problem.

the birds all did strange things at takeoff and would kick in hover

intermittently. simply replace the tail drive gear assembly with the metal

one and get the high quality tail belt from tech-mp.com. :wink:

soneebee · 07-17-2007, 04:33 AM

Have you set the GY401 to digital? better set it to analog since you are using a JR servo.. they are not 100% compatible...

Magenta · 07-17-2007, 07:41 AM

Quote:

Originally Posted by soneebee

Have you set the GY401 to digital? better set it to analog since you are using a JR servo.. they are not 100% compatible...

Where did you get this info? I've never seen anything that even remotely implies a problem using the 3400 in digital mode on a 401. I've never had a problem either

garfro · 07-17-2007, 12:47 PM

OK guys......i am convinced it is slippage on the belt or plastic gears so have got new gears (metal) and a new belt,

any tips on replacing the front gear (easist way to dismantle)
Tail I can do

G

07-15-2007, 12:41 AM	#1
garfro Registered Users Join Date: May 2007 Location: RSM Ca	Heli spins hard on takeoff I have 450sa and am just about hovering but the last few times i have taken it out to practice it gets a few inches off the ground and starts spinning (cant remember left or right) 1st time the belt looked slack so tightened and it still does it ......took it apart and looked for broken teeth and belt wear but can see none, tail rotor seems to spin up ok Ant ideas???? G

07-15-2007, 12:49 AM	#3
Skiddz HF Support My HF Map location Join Date: May 2006 Location: Carlsbad, CA (USA)	More than likely, you've got the gyro working backwards. I strongly suggest you checkout Finless's gyro video HERE and pay particular attention to the final direction checks towards the end. Almost everyone who mentions this issue has the gyro direction reversed and has neglected to verify the proper operation of the gyro prior to spooling up the heli. Good luck! __________________ -Kevin No helicopters were harmed in the creation of this post. AMA CD # 7309, Turbine Waiver# RW 890 To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

07-15-2007, 12:55 AM	#4
Brent@paradise Registered Users Join Date: Nov 2006 Location: New Zealand	Do you use to be ablle to hover ok, whit out this problem? if so what changed? di you replace some stuff? what gyro have you got? Are the tail blades spining the correct way, are they on the correct way. __________________ Better to be in the air than under the ground. ************************************** trex 450 se stock trex cf 600 stock EP 200 se

07-15-2007, 01:01 AM	#7
Skiddz HF Support My HF Map location Join Date: May 2006 Location: Carlsbad, CA (USA)	So, you've been able to hover this thing before?? Or at least spool it up? Did the skids ever leave the ground before without it spinning? What kind of surface are you flying from? __________________ -Kevin No helicopters were harmed in the creation of this post. AMA CD # 7309, Turbine Waiver# RW 890 To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

07-15-2007, 01:11 AM	#9
Skiddz HF Support My HF Map location Join Date: May 2006 Location: Carlsbad, CA (USA)	Grass has a LOT of surface friction and I was thinking you'd never actually got the skids clear of the grass and therefor never seen the spinning problem... I'd certainly take a good look at the gyro setup and make sure you've got everything centered up mechanically (gyro in rate mode - or even better - completely out of the loop) and make sure the gyro initializes in HH mode AND is operating the proper direction.. Which gyro/servo are you running? __________________ -Kevin No helicopters were harmed in the creation of this post. AMA CD # 7309, Turbine Waiver# RW 890 To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

07-15-2007, 12:45 AM	#2
ken6881 Registered Users Join Date: Jun 2007 Location: henderson, KY	after your in the air dose it still do it. if not before you take off putt a little right rudder into it and it will stop it. my se v2 was doing the same thing at the first time youd take off on a new pack so i took off then landed measured the tail pitch then set the center of the servo at that.

07-15-2007, 01:15 AM	#10
garfro Registered Users Thread Starter Join Date: May 2007 Location: RSM Ca	the gyro is a GY401 with JR 3400 digital .....I am going to check the gyro but like i said it was ok before then started doing it ..no repairs/crashes etc G

07-15-2007, 03:45 AM	#11
Big Fil Registered Users My HF Map location Join Date: Mar 2007 Location: Santa Rosa, CA	reverse the gro direction __________________ Mikado Model Helicopters Edge Blades

07-15-2007, 03:32 PM	#12
nwtampaguy34 Registered Users My HF Map location Join Date: Feb 2007 Location: Tampa Fl	check the gear that holds your tail belt on inside the block. if it is plastic it could be starting to frey off the top part that holds the belt on. mine started doin the same thing one day and just looking from above while the heli was spinning up i could see it shaking a bit. then i discovered it was just about to break and of course i have the metal gear one now and no prob since. if u allready have the metal belt gear then i guess this wont help you. I am shure you will figure it out with all us frieks on here

07-15-2007, 04:21 PM	#13
jeffk Registered Users My HF Map location Join Date: May 2007 Location: NE Ohio	I'm wondering if you haven't got some binding in the tail rotor control rod, pitch slider, or perhaps the tail servo itself isn't working. Just because the tail rotor spins up doesn't mean that it's working properly. Check your linkage and tail pitch slider for proper operation. __________________ RC Helicopter product reviews and general musings: The HeliGeek's Blog To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

07-16-2007, 06:42 AM	#14
Pinecone Registered Users Join Date: Sep 2006 Location: Maryland	If you changed the belt, did you check to make sure you twisted it hte right way the tail blades are turning the correect direction (front blade turns UP intothe rotor wash)? __________________ Terry AMA#47402, IRCHA # 3395 Blade CP "Pro", Trex 450SE, PiccoZ, Quick of Japan EP8v2 EX, Hurricane 550, Hurricane 200, JR Vibe 50, Blade mCX, Bergen Intrepid Gasser, Pantera 50, Blade mSR, Novus CP

07-16-2007, 03:16 PM	#15
metsurf Registered Users Join Date: May 2007 Location: Denmark	I have just had the exact same situation as nwtampaguy34,- the gear didn't follow the shaft when the RPM's increased. I tried to CA it on the shaft and it worked fine, but I have now ordered the HS1216 for replacement. It seems that plastic parts in this position is unreliable. I was hard to tell because at low speed it all looked okay, but immediately at takeoff it began spinning left. _____________________ Steen

07-16-2007, 04:52 PM	#16
double0757 Registered Users My HF Map location Join Date: Apr 2007 Location: West Palm Beach, Florida	Garfro: I had something similar happen. When I was learning I hover one morning didn't do anything to the heli that afternoon it did what is happening to you. Suggestion. spool it up on cement or tile, put left and right rudder to see if it respond. then take it out side and see if it does it when you take it airborne. If you have a good rudder and goes out of control piro of the ground then is the Gyro reversing switch on the gyro it self. Can't explain why but it happen to me. Double O __________________ Trex 600N KME Diamond 60 engine w/ Hattori (18, for 90eng.) muffler, jr8717, Spartan 760/Futaba9256, 610mm Rotortech, AR7100r 8v. Logo 600 FBL w Pro-Bar & Spartan 760 on tail, Scorpion on 10S and Jazz ESC(big) JRX9303 TX.

07-16-2007, 11:56 PM	#17
NINJA RICK Registered Users Join Date: Dec 2006 Location: MARYLAND	I have now seen three new 450sa with the slipping tail belt drive gear problem. the birds all did strange things at takeoff and would kick in hover intermittently. simply replace the tail drive gear assembly with the metal one and get the high quality tail belt from tech-mp.com. :wink:

07-17-2007, 04:33 AM	#18
soneebee Registered Users Join Date: Apr 2006 Location: manila, Philippines	Have you set the GY401 to digital? better set it to analog since you are using a JR servo.. they are not 100% compatible... __________________ Walkera DF04 Heli

07-17-2007, 12:47 PM	#20
garfro Registered Users Thread Starter Join Date: May 2007 Location: RSM Ca	OK guys......i am convinced it is slippage on the belt or plastic gears so have got new gears (metal) and a new belt, any tips on replacing the front gear (easist way to dismantle) Tail I can do G

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode