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Sep 13, 2009, 02:45 PM
Fly Runaway Fans
The reason you can't count on it, is that as TX power shuts down, it may issue spurious commands. If the failsafe HOLDS those commands, which it does, bad things can happen.

The failsafe is intended to deal with loss of connectivity, NOT TX powerdown. And the TX powerdown cannot be counted upon to promptly cease all transmission without blurting out some semiconscious commands. It could be designed to do so, but I don't believe it was.
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Sep 13, 2009, 07:24 PM
Registered User
Thanks for thetips. Will check the TH curves and rebind my X9303.
Sep 28, 2009, 02:58 PM
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Mikeshobby's Avatar
Sorry to ressuresct an old thread but I'm al little confused about Throttle Hold too. My DX6i has both a "Throttle Cut' and "Throttle Hold". the Throttle Cut has a button on the top right corner that cuts the throttle completely when pressed and resumes when released. This is what Iv'e been using the the event of a crash becuase it stops all power to the motor immediately.

I thought Throttle Hold was somewhere along the same lines as Throttle Cut only I can adjust how much throttle I want to have when I flick the switch. Is this right?
Sep 28, 2009, 03:57 PM
Registered User
Throttle Hold is linked to curves, the throttle and pitch curves. For a nitro helicopter with Throttle Hold you could set throttle to idle rpm, with the desired pitch curve. Then use Throttle Cut to shut down the engine from idle. Throttle Cut is just the Throttle, no change to pitch curve, you get the pitch curve from the current flight mode.
Jan 18, 2011, 02:47 PM
Diverted by planks
tracknoob's Avatar
I know this is a *very* old thread, but I can't resist posting here, in case someone is like I am and finds it via Google search.

I am a total newb to RC, but I would like to add some info and experience that I think could help clear things up for others.

I found the thread because I just bought a Blade400, partly because of the DX6i radio, and am getting set up and familiarized with the transmitter, and was searching to find what 'throttle cut' does.

So, to the point:

Throttle hold is exactly what it says it is: when selected, the radio will place the throttle setting to a pre-set value, regardless of the the joystick position, and there it will stay. On the Spektrum radios, though, this value might be what you set it to using the menu, like the DX6i, but at least on the HP6DSM, if not more models of transmitter, the throttle hold takes the value of the stick it sees at bind time! I'm sure most know this, but I'll bet at least a few do not. So if the stick is inadvertently left at partial (or full) throttle when binding, then that is what throttle hold will recall.

Since this value is normally set to idle, or 0%, or bottom of stick, or even -5% by some, then it usually works as expected. But some people have characterized throttle hold as a kill switch or positive safety device. Well, it is, or at least can be -- but only if you have set it and tested it to function that way! Trust but verify.

BTW, this was particularly confusing to me, because as a newbie I already had to get over 'stunt mode' also being called 'idle up', and the throttle could be 100% or near it (depending on curve) regardless of it being placed at the bottom of travel - now add to that confusion that in 'idle up' (which isn't idle!) that I would use throttle hold (which isn't holding, but killing!) in an emergency. Whew. Yes, it makes sense - mostly, but it takes a little assimilation!

This was new to me -- the other two Spektrum radios I used did not have this feature. I thought I would like it, as it does not bring the potential ambiguity that throttle hold brings with it, but the problem is that this is a MOMENTARY contact switch! So, when you let go, the throttle will resume to wherever it was. Well, that's not very useful to my needs and I can't imagine a time I would use this, when by convention, habit, and programming, I will already be using throttle hold to stop the throttle and make the heli safe. So, I suggest you program this switch to start the timer, if that's more convenient for you than using the trainer switch, or just ignore it altogether.
Last edited by tracknoob; Jan 18, 2011 at 02:54 PM.
Jan 25, 2011, 03:34 PM
Registered User
Thought I'd just add:

Yes throttle cut is only useful for Nitro engines. It is used to drive the throttle servo all the way to close the carb and therefore cut the engine. In the original post there was something about -20%. This refers to the servo travel. In Spektrum (Perhaps other radios) the default servo travel is +- 100% but you can make it larger I think up to 125%. On some ESCs you can actually get a bit more power this way.

So usual range is +-100% e.g. The throttle servo would idle somewhere around 0% perhaps a bit above, and you would want a negative value on the throttle cut to move the servo past idle.
Jan 25, 2011, 04:17 PM
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Bad Creation's Avatar
Sorry but i would have too disagree take a look at this picture Name: 100_1079.jpg
Views: 435
Size: 93.5 KB
Description: and it does work with electric motor
Jan 25, 2011, 04:42 PM
Diverted by planks
tracknoob's Avatar
Originally Posted by Bad Creation View Post
Sorry but i would have too disagree take a look at this picture Attachment 3755867 and it does work with electric motor

heh heh

I think you two are talking past each other:

xalen: 'It's only useful for nitro engines.'
Bad Creation: 'I disagree; it works with electric motors...'

I think you are both right:

* The function certainly can be mapped to an electric, and it does hold... until you let the spring loaded switch go, at which time you get full torque instantly, right up to the current lever throttle position - not usually what anyone wants to see.

* It seems it might only be useful to 'kill' a nitro engine, but not much good for us electric guys... except maybe to map as our timer switch.
Jan 26, 2011, 07:13 AM
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Bad Creation's Avatar
Well i guess i should have paid more attention to the question sorry
Jan 28, 2011, 07:32 PM
I have a DX6i and when I set up a helicopter "Throttle Hold" is a default setting. As far as I can figure out you can't turn it off. You can set up "Throttle Cut" if you like but the throttle is only off as long as you hold the button in. Let go of the button and the throttle is back on.
Jan 31, 2011, 04:01 PM
Registered User
Yes that's exactly what I meant :-)
Feb 22, 2011, 09:08 PM
Registered User
Thanks for resurrecting this thread as I did find it through Google, in trying to understand "throttle hold"

In my Noob brain throttle hold sounded like a cruise control where it would stick the throttle in one position and it confused me to hear it being used as a kill switch. I guess by default the preset position is 0% (on a DX6i) so it can be used as a kill switch. I agree trust but verify. I have watched my mSR fall out of the sky onto the bed to make sure this switch worked as expected. I will do the same with the mCPx.

As for the throttle cut, I agree having it momentary is less than perfect on an electric heli, but I can see how it could be useful on an electric heli...

when things go bad it all happens too fast. You might press the throttle cut and prepare for impact and then after a moment, when things settle down, (while still holding the throttle cut) you take the controller out of stunt mode and lower the throttle or hit your throttle hold switch. Either way you helped to prevent damage.
Last edited by jscott1; Feb 22, 2011 at 09:15 PM.
Feb 22, 2011, 09:50 PM
Diverted by planks
tracknoob's Avatar
Originally Posted by jscott1 View Post
Thanks for resurrecting this thread as I did find it through Google, in trying to understand "throttle hold"
I am glad it helped!

And BTW, the reference I made to bind time snagging the throttle setting is now, unfortunately field-tested by me personally to be the case on the B400!

I don't know if the factory did it (unlikely) or I did it in some forgotten tweaking session, but sure enough, a few days ago, I made the mistake of leaving the bird powered up, and I backed out of the DX6i menus and selected 'change model,' just in order to verify a few settings from my other Blade. So, I in effect, broke the connection to the heli. I would not have done this had I thought about it, but who would think it's dangerous to just verify a setting or navigate to another model while your heli is sitting quietly? Well, the heli spooled itself to about 50% throttle and just sat there, even though the stick was full down and throttle hold engaged on the radio. I was freaked! It was vibrating closer and closer to the edge of my 'heli-pad' and also slowly starting to slowly rotate counter-clockwise... Thank God I did not have any positive pitch in at that setting... I realized I had screwed up, and madly started switching the radio on and off, and toggling throttle hold without even really thinking clearly... fortunately for me (I think!) this heli is bound in model #1 position, so when the radio started back up, the receiver re-established communication, and the thing quit. I was sopping wet from the idea of that heli seeming ready to run amok with no input from me.

Needless to say, I rebound with the correct settings and then, with the heli bolted down to the ground, I verified that with the radio turned off, it did not spool back up, in case I'm ever dumb enough to turn off the radio with the model on, again.
Feb 23, 2011, 12:36 AM
Registered User
Originally Posted by tracknoob View Post
I am glad it helped!

And BTW, the reference I made to bind time snagging the throttle setting is now, unfortunately field-tested by me personally to be the case on the B400!
Wow! Thanks again, for that lessons learned. I would have never thought that messing with the menus on the Tx could be dangerous, but you live and learn. That's another reason to start out on less lethal ultra-sub micros. They can do some damage, but not nearly as much. I was practicing nose in hover on mSR and almost flew into my face. That would not have been pretty.
Feb 23, 2011, 03:11 AM
Registered User
I guess the throttle cut button is not found on most radios. I guess spektrum gave the DX6i some extra buttons like the throttle cut just as it can be used with nitro engines. and easier way to cut out the engine during idle

on the DX7, or 9303 this throttle cut is not found, but since the radio is more programmable with we could assign a switch to perform what the Throttle cut does on DX6i. Like on my radio for me to cut off the engine i have to switch the AUX2 or flap switch to function as the throttle cut.

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