T-rex 450X tail dilemma

[Neil66]

Please help as I'm losing my sanity. I bought a supposedly RTF T-Rex
about 3 weeks ago partly assembled. I haven't had a lot of experience
with helis apart from 2 months battling with a Walkera #60 which is now
in the bin.
I've managed to sort out the wiring and have actually had lift off a
couple of times, trouble is I can't stop the tail spinning no matter
what I do, I've put a digital servo on & a GY401 Gyro. The heli came
with the extended boom and 325mm blades and all the head bits are
alloy. I've put the alloy tail upgrade and new blades on it and I've
read instructions to the point I can almost recite them but I can't get
my head round this at all. It seems as if there isn't enough power in
the tail to counter the front end, I can see the Gyro is trying to
correct it but once it gets light on the skids round it goes.
Any ideas would be really welcome.
Thanks.


--
Neil66
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[The OTHER Kevin in San Diego]

On Wed, 6 Sep 2006 20:34:44 +0100, Neil66
<Neil66.2dqad3@no-mx.themodelzone.org> wrote:

>
>Please help as I'm losing my sanity. I bought a supposedly RTF T-Rex
>about 3 weeks ago partly assembled. I haven't had a lot of experience
>with helis apart from 2 months battling with a Walkera #60 which is now
>in the bin.
>I've managed to sort out the wiring and have actually had lift off a
>couple of times, trouble is I can't stop the tail spinning no matter
>what I do, I've put a digital servo on & a GY401 Gyro. The heli came
>with the extended boom and 325mm blades and all the head bits are
>alloy. I've put the alloy tail upgrade and new blades on it and I've
>read instructions to the point I can almost recite them but I can't get
>my head round this at all. It seems as if there isn't enough power in
>the tail to counter the front end, I can see the Gyro is trying to
>correct it but once it gets light on the skids round it goes.
>Any ideas would be really welcome.
>Thanks.

That tail and Gyro should have PLENTY of authority for you assuming
you've got enough headspeed. (headspeed is related to TR speed so
you're gonna need to make sure the mains are spinning 2500+ RPM - Mine
does about 2900 RPM on a 13T pinion and the new "blue" gears)

head over to http://www.helifreak.com and check out Finless Bob's Tech
Room. He's got a nice 10-11 minute video on how to set up the Rexy's
tail rotor and the GY401. Should get you right in the ballpark for
your trimming flights.

[Neil66]

OK thanks I'll give it a go.


--
Neil66
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[Beav]

"Neil66" <Neil66.2dqad3@no-mx.themodelzone.org> wrote in message
news:Neil66.2dqad3@no-mx.themodelzone.org...
>
> Please help as I'm losing my sanity. I bought a supposedly RTF T-Rex
> about 3 weeks ago partly assembled. I haven't had a lot of experience
> with helis apart from 2 months battling with a Walkera #60 which is now
> in the bin.
> I've managed to sort out the wiring and have actually had lift off a
> couple of times, trouble is I can't stop the tail spinning no matter
> what I do, I've put a digital servo on & a GY401 Gyro. The heli came
> with the extended boom and 325mm blades and all the head bits are
> alloy. I've put the alloy tail upgrade and new blades on it and I've
> read instructions to the point I can almost recite them but I can't get
> my head round this at all. It seems as if there isn't enough power in
> the tail to counter the front end, I can see the Gyro is trying to
> correct it but once it gets light on the skids round it goes.
> Any ideas would be really welcome.

You've got the gyro "sensing" in the wrong direction it would seem.

Try this:-

Hold the heli (with everything switched on) in one hand and rotate it to the
left (nose left, not tail). Check the tail rotor servo while you're doing it
and it SHOULD be giving a "nose right" command to the tail blades. You can
check if the "nose right" command is correct by looking at the pitch of the
tail blades when you work the transmitter stick. Right tail gives more blade
pitch.


--
Beav

VN 750
Zed 1000
OMF# 19

[Steve R]

"Neil66" <Neil66.2dqad3@no-mx.themodelzone.org> wrote in message
news:Neil66.2dqad3@no-mx.themodelzone.org...
>
> Please help as I'm losing my sanity. I bought a supposedly RTF T-Rex
> about 3 weeks ago partly assembled. I haven't had a lot of experience
> with helis apart from 2 months battling with a Walkera #60 which is now
> in the bin.
> I've managed to sort out the wiring and have actually had lift off a
> couple of times, trouble is I can't stop the tail spinning no matter
> what I do, I've put a digital servo on & a GY401 Gyro. The heli came
> with the extended boom and 325mm blades and all the head bits are
> alloy. I've put the alloy tail upgrade and new blades on it and I've
> read instructions to the point I can almost recite them but I can't get
> my head round this at all. It seems as if there isn't enough power in
> the tail to counter the front end, I can see the Gyro is trying to
> correct it but once it gets light on the skids round it goes.
> Any ideas would be really welcome.
> Thanks.

Neil,

When you say it's spinning, do you mean it's "oh sh*t" spinning, or is it
just drifting? If it's the first, then you probably have the gyro sensing
going the wrong way. If it's the second, keep reading....... ;-)

Also, the GY401, if you didn't know, wants to be initialized in heading hold
mode. There is a small red light on top of the gyro that should be lit
solid if it's in heading hold mode and the initialization process is
successful. If it's off, or more likely, blinking after you first turn on
the system, then it won't hold properly.

One other thing to check, which you probably know but I'll mention just in
case:

Make sure all tail compensation or revolution mixes in the transmitter are
turned off! You can't have any internal mixes that effect the rudder
channel active in the transmitter. Even after a successful initialization
process, the light will blink if you move the rudder stick. That part is
normal. It will also blink if you've got a rudder mix active so you could
have a couple of things going on here.

If you're running the gyro in standard mode, you can only trim it by
adjusting the mechanical linkage on the model. Do not use the trim on the
transmitter. The gyro will see that as a command to turn the helicopter and
it will drift around.

Sorry if this is blatantly obvious stuff but from our POV, we never know.
Good luck and ask more questions if you need to.

Fly Safe,
Steve R.

[Neil66]

Thanks for replying, it starts off well and looks like the tail is going
to hold but when it gets light on the skids it spins, not really fast
but uncontrollably. Even with full right stick it just keeps going.
I've checked evrything is working the correct way and not reversed,
I've even reversed them all just to eliminate that possibility. To put
it in simple terms I'd say there isn't enough thrust from the tail to
push it sideways. I make sure it's always in head holding mode, light
comes on and stays on and blinks when the heli starts to twitch or when
I apply stick, revo is inhibited and I've tried gyro gain from +100% to
-100% in 10% incriments switching off between each adjustment.
Transmitter is a Futaba 6EXHP, don't know if that has any bearing on
anything just thought I'd mention it.
Cheers for your help.
Neil.


--
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[The OTHER Kevin in San Diego]

On Thu, 7 Sep 2006 21:29:07 +0100, Neil66
<Neil66.2ds7mx@no-mx.themodelzone.org> wrote:

>
>Thanks for replying, it starts off well and looks like the tail is going
>to hold but when it gets light on the skids it spins, not really fast
>but uncontrollably. Even with full right stick it just keeps going.
>I've checked evrything is working the correct way and not reversed,
>I've even reversed them all just to eliminate that possibility. To put
>it in simple terms I'd say there isn't enough thrust from the tail to
>push it sideways. I make sure it's always in head holding mode, light
>comes on and stays on and blinks when the heli starts to twitch or when
>I apply stick, revo is inhibited and I've tried gyro gain from +100% to
>-100% in 10% incriments switching off between each adjustment.
>Transmitter is a Futaba 6EXHP, don't know if that has any bearing on
>anything just thought I'd mention it.
>Cheers for your help.
>Neil.

You sure nothing is binding? Got enough servo throw? Again, what's
the headspeed? If it's too low, the TR will be spinning too low and
not generating enough thrust. Low headspeed and lots of pitch means
lots of torque the TR has to compensate for.

Know anyone with another 401 you can try? Perhaps you've got a bum
unit.

I still suggest checking out Finless Bob's 401 setup video over at
www.helifreak.com.

[G-Dawg]

"Neil66" <Neil66.2ds7mx@no-mx.themodelzone.org> wrote in message
news:Neil66.2ds7mx@no-mx.themodelzone.org...
>
> Thanks for replying, it starts off well and looks like the tail is going
> to hold but when it gets light on the skids it spins, not really fast
> but uncontrollably. Even with full right stick it just keeps going.
> I've checked evrything is working the correct way and not reversed,
> I've even reversed them all just to eliminate that possibility. To put
> it in simple terms I'd say there isn't enough thrust from the tail to
> push it sideways. I make sure it's always in head holding mode, light
> comes on and stays on and blinks when the heli starts to twitch or when
> I apply stick, revo is inhibited and I've tried gyro gain from +100% to
> -100% in 10% incriments switching off between each adjustment.
> Transmitter is a Futaba 6EXHP, don't know if that has any bearing on
> anything just thought I'd mention it.
> Cheers for your help.
> Neil.
>
>
> --
> Neil66

Make double sure about "Reverse" on the Gyro itself. Don't want to overlook
anything but there is a small switch on the 401. I had to reverse mine.
Before I did that, every time it got light on the skids that sucker started
spinnging bad. Killed several hours and a carbon tailfin figuring that one
out.

[Philip Goodwin]

"Neil66" <Neil66.2dqad3@no-mx.themodelzone.org> wrote in message
news:Neil66.2dqad3@no-mx.themodelzone.org...
>
> Please help as I'm losing my sanity. I bought a supposedly RTF T-Rex
> about 3 weeks ago partly assembled. I haven't had a lot of experience
> with helis apart from 2 months battling with a Walkera #60 which is now
> in the bin.
> I've managed to sort out the wiring and have actually had lift off a
> couple of times, trouble is I can't stop the tail spinning no matter
> what I do, I've put a digital servo on & a GY401 Gyro. The heli came
> with the extended boom and 325mm blades and all the head bits are
> alloy. I've put the alloy tail upgrade and new blades on it and I've
> read instructions to the point I can almost recite them but I can't get
> my head round this at all. It seems as if there isn't enough power in
> the tail to counter the front end, I can see the Gyro is trying to
> correct it but once it gets light on the skids round it goes.
> Any ideas would be really welcome.
> Thanks.

Make sure that the belt is tight enough and not slipping. The tail rotor
blades should also be rotating up toward the main rotor in a clockwise
direction as viewed from the side with the nose of the copter to your left..
This also sounds stupid but make sure your tail rotor blades are on
correctly and the tail rotor hub is tight on the rotor shaft. You might also
want to check the servo and make sure the gears are holding under a load.

Phil

[Neil66]

Sussed it at last, something The other Kevin said got me thinking, the
pitch on the main rotor was incredibly high, as I said initially I
didn't build the thing and I'm pretty new to all this so I never
thought to check, don't know exactly what it was set at as I don't have
a guage, just ordered one though. Anyway it's going like a dream now so
thanks for all your help.
Neil.


--
Neil66
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[The OTHER Kevin in San Diego]

On Sat, 9 Sep 2006 13:42:31 +0100, Neil66
<Neil66.2dvbxz@no-mx.themodelzone.org> wrote:

>
>Sussed it at last, something The other Kevin said got me thinking, the
>pitch on the main rotor was incredibly high, as I said initially I
>didn't build the thing and I'm pretty new to all this so I never
>thought to check, don't know exactly what it was set at as I don't have
>a guage, just ordered one though. Anyway it's going like a dream now so
>thanks for all your help.
>Neil.

Nice. I love my little 'rex and try and get in 3-4 batteries each day
on it..

I hope it's big brother, the Trex 600 flies as well.. Just need a
gyro and I'll be able to get 'er in the air.

[Pete]

I just had a similar problem today with a loose tail (heli).
It turned out that the guy had put the heli in and he had replaced the tail
shaft. He is also new to heli's and was unaware that the tail blades should
rotate into the main downwash.

He set his tail up to rotate down with the downwash. This made the tail
blades extremely ineffective. It seemed that the tail pitch had too little
throw, even though the pitch was at full. The tail only had an effect when
the motor was stopped and the main + tail were freewheeling.

He had put the 1/4 turn in the belt drive the wrong way.

I hope this is of some use.

Regards.

--
Pete . .

------ Reply Separator ------

"Neil66" <Neil66.2dvbxz@no-mx.themodelzone.org> wrote in message
news:Neil66.2dvbxz@no-mx.themodelzone.org...
>
> Sussed it at last, something The other Kevin said got me thinking, the
> pitch on the main rotor was incredibly high, as I said initially I
> didn't build the thing and I'm pretty new to all this so I never
> thought to check, don't know exactly what it was set at as I don't have
> a guage, just ordered one though. Anyway it's going like a dream now so
> thanks for all your help.
> Neil.
>
>
> --
> Neil66
> ------------------------------------------------------------------------
> Neil66's Profile: http://www.themodelzone.org/forum/member.php?u=800
> View this thread: http://www.themodelzone.org/forum/showthread.php?t=15089
>

[The OTHER Kevin in San Diego]

On Sat, 9 Sep 2006 23:10:37 +0200, "Pete"
<zs5actRemovethis@mweb.co.za> wrote:

>I just had a similar problem today with a loose tail (heli).
>It turned out that the guy had put the heli in and he had replaced the tail
>shaft. He is also new to heli's and was unaware that the tail blades should
>rotate into the main downwash.
>
>He set his tail up to rotate down with the downwash. This made the tail
>blades extremely ineffective. It seemed that the tail pitch had too little
>throw, even though the pitch was at full. The tail only had an effect when
>the motor was stopped and the main + tail were freewheeling.

Having the blades rotate up into the downwash really only "helps" in a
hover. With any lateral movement (forwards, backwards, left or right)
the main's downwash is displaced from the TR.

Even on full scale ships, some TRs rotate up "into" the downwash and
some don't.

[Beav]

"The OTHER Kevin in San Diego" <skiddz "AT" adelphia "DOT" net> wrote in
message news:u4b6g29hh8lpb4d8j5s1div811f5v4rmt5@4ax.com...
> On Sat, 9 Sep 2006 13:42:31 +0100, Neil66
> <Neil66.2dvbxz@no-mx.themodelzone.org> wrote:
>
>>
>>Sussed it at last, something The other Kevin said got me thinking, the
>>pitch on the main rotor was incredibly high, as I said initially I
>>didn't build the thing and I'm pretty new to all this so I never
>>thought to check, don't know exactly what it was set at as I don't have
>>a guage, just ordered one though. Anyway it's going like a dream now so
>>thanks for all your help.
>>Neil.
>
> Nice. I love my little 'rex and try and get in 3-4 batteries each day

It must be full by now Kev, and isn't it illegal or something to do that
with a small furry creatures where you live?


> on it..
>
> I hope it's big brother, the Trex 600 flies as well..

Try shoving a biggger battery in it. I'm sure it'll fly instantly and very
far:-)


--
Beav

VN 750
Zed 1000
OMF# 19

[The OTHER Kevin in San Diego]

On Sun, 10 Sep 2006 20:27:24 GMT, "Beav"
<beavis.original@ntlwoxorld.com> wrote:


>> Nice. I love my little 'rex and try and get in 3-4 batteries each day
>
>It must be full by now Kev, and isn't it illegal or something to do that
>with a small furry creatures where you live?

I'm sure it is, but I imagine over on your side of the pond it's not
only legal, but jolly good fun!

>> I hope it's big brother, the Trex 600 flies as well..
>
>Try shoving a biggger battery in it. I'm sure it'll fly instantly and very
>far:-)

Christ, the two packs I've got for it are already the size of a small
furry creature....

Expecting my new charger for the things any second now.. Hopefully,
the gyro will be here by week's end and I can test your theory.