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Model Forum / Radio Controlled / Air Models / September 2006



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#%*@ing computer Tx programming

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Robert Scott - 17 Sep 2006 03:23 GMT
I have a pretty good handle on radio programming, or so I thought.  I've
used a Futaba 8U Super for several years and just bought a 9C Super (which
is much easier to program).  I've used the mixing capabilities to clean up
my knife edge flight, counter the pitch affects of deployed flaps, etc..

But setting up the throttles on a twin has frustrated me.  When I set up a
twin on my 8U, I couldn't get the mix to work properly and ended up using
"throttle needle mixing" to get the two throttles to work CLOSE to in
unison.  I just tried it with my 9C and couldn't get it to work properly.

I used a simple, linear mix with Channel 3 the master and Channel 8 the
slave.  I nulled the control for Channel 8 in the Aux channel menu.  In the
program mix 1 menu, I have 100% on both the arrow-up and arrow-down boxes.
"Link" is off and "Trim" is on.  0% offset.

The end-point, sub-trim and trim settings for both channels are untouched at
100%.  I haven't set up any idle down or throttle cut yet; they are default
at "inhibited".

The slaved throttle moves in unison with the master until about 75%
throttle, when it stops while the Channel 3 throttle continues to open.
This is the same problem I ran into when I set up a twin on the 8U.  There
is no information in either manual regarding this.  The Don Edberg Futaba 8U
book and the Futaba 9C website FAQ didn't mention it either.

Am I overlooking something?

I may very well dream about smashing both radios with a big hammer tonight
as I sleep. :-)

Thanks for any advice,
desmobob
MLB - 17 Sep 2006 09:11 GMT
> I have a pretty good handle on radio programming, or so I thought.  
> I've used a Futaba 8U Super for several years and just bought a 9C
[quoted text clipped - 31 lines]
> Thanks for any advice,
> desmobob

Hello,

I'm a 9C user,

I had a look at the 9C manual and 9C User's Guide (by Annmarie Cross).

First, servos travel are different (+- 40° for channel 1 to 4 and +-55°
for channel 5 to 8). Look at the END POINT Page.

For the 2 engine throttle setup you need, I think is better to slave
one of the auxiliary channels to the Throttle one. I would not rely on
idle mixing. If needed, use the end point adjustment on the slaved
channel to have the right travel (idle and full power).

Have a look at the Futaba FAQ web page. There are some undocumented tips.

I have a two servos (airbrake setup on the throttle channel of my 9C
but I'm not sure if I use a Mix or Y cord for that purpose). I will
check later and keep you in touch.

Hope to help you,

MLB
MLB - 17 Sep 2006 09:47 GMT
> I used a simple, linear mix with Channel 3 the master and Channel 8 the
> slave.  I nulled the control for Channel 8 in the Aux channel menu.  In
> the program mix 1 menu, I have 100% on both the arrow-up and arrow-down
> boxes. "Link" is off and "Trim" is on.  0% offset.

Hello,

Here is an update:

On my Airbrake setup, I use two servos and two channels.

Master is Throttle, Slave is Gear (No Use on that aircraft - Flying
Wing glider Cortina).

Mix rate is +100/-100, Offset is 50%
Mix ON, Link ON?, Trim ON, SW Stk Throttle, Posi NULL.

End points are Throttle 105/105, Gear 105/100 to adjust servo travel

Bye,

MLB
MLB - 17 Sep 2006 10:06 GMT
>> I used a simple, linear mix with Channel 3 the master and Channel 8 the
>> slave.  I nulled the control for Channel 8 in the Aux channel menu.  In
[quoted text clipped - 18 lines]
>
> MLB

Here is a link for an advanced two engines setup. Not quick and dirty
but quite tricky...

http://www.futaba-rc.com/faq/faq-9c-q511.html

Have a nice flight,

MLB
Robert Scott - 18 Sep 2006 12:07 GMT
Thanks for your help, MLB.

Good flying,
desmobob
Robert Scott - 18 Sep 2006 23:59 GMT
>I have a pretty good handle on radio programming, or so I thought.  I've
>used a Futaba 8U Super for several years and just bought a 9C Super (which
[quoted text clipped - 25 lines]
> I may very well dream about smashing both radios with a big hammer tonight
> as I sleep. :-)

I got a response from Futaba Service....  setting the Offset to 50% has the
throttle and slave in unison for full travel now.  But now, I can't get the
Idle Down and Throttle Cut to work on the slave channel.  I have the Link
set to On.... still no go.

I should have bought a JR!

Good flying,
desmobob
Robert Scott - 20 Sep 2006 23:55 GMT
>>I have a pretty good handle on radio programming, or so I thought.  I've
>>used a Futaba 8U Super for several years and just bought a 9C Super (which
[quoted text clipped - 33 lines]
>
> I should have bought a JR!

I heard from Futaba Service again (they are quick).

"Unfortunately both of those functions will only work on the master
channel."

If you're going to be setting up multi-engine models, you may want to skip
the Futaba 9C Super.  I spent $400 on a computer radio and have to use a
Y-harness on the throttles so I can have throttle cut and idle down on both
engines.  :-(

Good flying,
desmobob
Rob - 21 Sep 2006 16:29 GMT
Just a thought. I've seen this done with float planes to enhance on the
water steering.  Try connecting your throttle servos to 2 aux channels and
slaving both to the throttle channel. You should also be able to program a
mix with rudder if required to give differential thrust.
I am working on a twin and will be trying this with my 9C soon.

>>>I have a pretty good handle on radio programming, or so I thought.  I've
>>>used a Futaba 8U Super for several years and just bought a 9C Super
[quoted text clipped - 47 lines]
> Good flying,
> desmobob
Robert Scott - 21 Sep 2006 22:13 GMT
> Just a thought. I've seen this done with float planes to enhance on the
> water steering.  Try connecting your throttle servos to 2 aux channels and
> slaving both to the throttle channel. You should also be able to program a
> mix with rudder if required to give differential thrust.
> I am working on a twin and will be trying this with my 9C soon.

That will work fine for getting the throttles to move in unison, but it
still won't allow the use of Idle Down and Throttle Cut.  I feel Throttle
Cut is an important safety feature and I use it on all my models.  Idle Down
is pretty nice to have on a multi-engine model too....

Good flying,
desmobob

>>>>I have a pretty good handle on radio programming, or so I thought.  I've
>>>>used a Futaba 8U Super for several years and just bought a 9C Super
[quoted text clipped - 48 lines]
>> Good flying,
>> desmobob
Doug McLaren - 21 Sep 2006 17:21 GMT
| I heard from Futaba Service again (they are quick).
|
[quoted text clipped - 5 lines]
| Y-harness on the throttles so I can have throttle cut and idle down on both
| engines.  :-(

You could get your basic V-tail/Elevon/flaperon _hardware_ mixer ($15
or so) and put it in your plane, with your throttle channel as the
input that adjusts both engines equally, and another channel as the
input that adjusts them unequally.

Then your throttle cut and idle down would still work, and you could
adjust them seperately via your other channel.

Signature

Doug McLaren, dougmc@frenzied.us
`Sir, I protest! I am NOT a merry man!'  --Worf, ST:TNG

Robert Scott - 21 Sep 2006 22:19 GMT
> | I heard from Futaba Service again (they are quick).
> |
[quoted text clipped - 15 lines]
> Then your throttle cut and idle down would still work, and you could
> adjust them seperately via your other channel.

Doug,

That's an interesting and clever idea.   I think I'll pass though....
although those units are pretty straightforward, getting linkages to the two
throttles would be mighty interesting, indeed!  (Maybe not too bad using
flex cables....)

I stuck a Y-harness on Channel Three and did the fine-tuning on the linkages
to get them nicely in synch.  I'm done messing with setting up twin
throttles for this season!   I have a Wing Mfg. A-26 Invader kit in the shop
that I hope to build this winter.  I'll be motivated to mess with twin
throttle set-up again in the Spring if I get it built.

Good flying,
desmobob
Doug McLaren - 21 Sep 2006 22:56 GMT
| > You could get your basic V-tail/Elevon/flaperon _hardware_ mixer ($15
| > or so) and put it in your plane, with your throttle channel as the
[quoted text clipped - 8 lines]
| throttles would be mighty interesting, indeed!  (Maybe not too bad using
| flex cables....)

Linkages?  No ...

Something like this is what I was referring to --

  http://www.combatwings.com/catalog/product_info.php?cPath=32&products_id=227&osC
sid=0140dbe4a3bdd9dbc970027f38535d3c

  http://www.bill-tek.com/Elevon.htm
  http://www.californiasailplanes.com/digimix.html

perhaps you're thinking of those setups where one servo moves another
servo back and forth, and that servo is what's connected to the
control surfaces?  That would work, but the modern electronic mixers
would be easier -- pretty much trivial to install.

Perhaps I shouldn't have said _hardware_ ... I meant hardware as in a
piece of eqipment you put into your plane, as opposed to programming
you do in your TX.

Signature

Doug McLaren, dougmc@frenzied.us
He was deeply in love. When she spoke, he thought he heard bells, as
if she were a dustcart reversing.

Robert Scott - 22 Sep 2006 01:44 GMT
> Perhaps I shouldn't have said _hardware_ ... I meant hardware as in a
> piece of eqipment you put into your plane, as opposed to programming
> you do in your TX.

Indeed.... "hardware" was the word that threw me off -- it doesn't take
much!  I was picturing the old mechanical type mixers. "Mechanical" was the
word I was thinking when I was looking at "hardware."

The mixers you linked to would make the project much easier, for sure.

If I try it, I'll let you know how it works.

Thanks again,
desmobob
 
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