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Old Oct 09, 2012, 01:48 AM
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Tucson, AZ, USA
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Throttle Cut-off switch Futaba 7C FASST

I have a Futaba 7C FASST radio. The other night I was in the process of setting up control throws on a new model before maiden the next morning. With the plane sitting on the kitchen floor, I was moving the rudder and bumped the throttle up just enough to start the plane rolling across the floor. Now I'm usually Mr. Safety and quickly shut off the motor and unplugged the battery. I then removed the prop.

This all started me thinking, could I mix a switch on my transmitter to use as a safety switch? Well, searching the internet ( if you what to find out anything about anything just search the internet ) I came up with the answer and thought others may benefit.

With computer radio transmitters, it is possible to assign a switch to disable the throttle function. In the example below, the throttle functions normally when the switch is in the up position. In the down position, no power can be applied to the motor.

Use the down position any time the plane is not flying. If you inadvertently bump the throttle stick, nothing happens.

Futaba example is shown. Note that the MASTER and SLAVE are the same the throttle channel, channel 3 on Futaba.

Futaba 7C
To use switch F ( or any of the other switches ) as a throttle disable:

P-MIX 1 > ON
MAS > CH3
SLV > CH3
SW > F ^ ( or any of the other switches )
RT > -100%
> +100%
OFS > SET
With the cursor on OFFSET and the throttle stick closed, press and hold the dial/press control on the transmitter.

It would really be nice it the manuals that come with these radios would include this little easy to program tip.
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Old Oct 09, 2012, 02:17 AM
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Threshold's Avatar
London UK
Joined Jul 2004
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on my Futaba T8 FG Super it won't let me select a model unless my programmed kill switch is on which is even safer. What is strange is that although I have been showing guys at the field how to do that with many radios they never seem to bother to do it. I guess they are waiting until they have a serious problem before finding out how to program their radios. I hope you have better results.
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Old Oct 09, 2012, 04:26 AM
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Letchworth, Great Britain (UK)
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Doesn't the 7C have a THR HLD function? If so, you simply set its throttle value to zero.
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Old Oct 09, 2012, 09:13 AM
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Yes it does, however this function is only in the Helicopter setup. So, I guess my question would be will this function be available in Acro/Aircraft setup for the model I'm using if activated in the Heli setup?
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Old Oct 10, 2012, 04:06 AM
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Letchworth, Great Britain (UK)
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No, if it's only available in heli mode, it will not be available when you switch back to acro mode. I no longer have my 7C, but I'm surprised the same or equivalent function doesn't exist in acro mode -- even the basic Futaba 6 trannies have some kind of throttle cut button or switch IIRC.
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Old Oct 10, 2012, 09:35 AM
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Joined Mar 2010
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My answer is a strap the holds the throttle down ALL THE TIME, except when actually flying. When I land the strap goes back on... For safety issues that can result in blood I like to be able to see the 'safety device' and know w/o a doubt that it's in place...
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Old Oct 10, 2012, 12:53 PM
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United States, FL, Miami
Joined Nov 2011
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Trying to figure out how to do it on the 8FG drove me crazy for a few days, until finally someone here told me how to do it (god bless him.. ). The key for electric was not to do it through the throttle kill function at all but rather through the motor function. I don't know whether it will help you or not as we don't have the same radio, but maybe it will point you in the right direction.
Good luck. I think it is worth setting up...
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Old Oct 13, 2012, 05:22 AM
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United States, MI, Middleville
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thanks for this, it really came in handy. now i dont have to install anymore disarm switches in my planes and can still use the servos
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Old Oct 13, 2012, 08:56 AM
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Arizona
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Wow, Guy, thanks. I was just thinking the other day if/how this could be done.
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Old Oct 13, 2012, 01:22 PM
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Arvada, CO
Joined Aug 2004
366 Posts
I program a mix from throttle to a three way switch. Only when the switch is in the middle position can the throttle be armed. That way if you bump it in any direction, the default is throttle off. It's been very helpful. I use this on both the 7C and the 8FG, not too hard to do.
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Old Oct 13, 2012, 01:48 PM
Fly it like you STOL it!
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United States, FL, Daytona Beach
Joined Jan 2011
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Anyone know how to do this on a jr x9303?
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