DX-7 failsafe, are optimally set up??

[Inspector Fuzz]

This may be obvious to some of you, but after hearing about the heli that slammed into the ground at Bham, possibly due to lockout, I thought it would be worth mentioning.
The DX7 has a very simplified failsafe. You turn on the transmitter during bind procedure with the controls in the position you want them to go in the event of a lockout.
At first I set my failsafe with the left stick all the way down, so the motor would go to idle. Problem is, it also goes to full negative pitch or at least some negative depending on your normal pitch cure. This will slam you into the ground at low altitude or kill all your blade speed at higher altitude.
What you want to do is set the fail safe in THROTTLE HOLD. Have the left stick in the middle at 0 degrees pitch and the motor at idle. The model is now unpowered, but you have a fighting chance of regaining control when the signal comes back.
JEFF

[Danal Estes]

Not true. Failsafe on spektrum is often misundertsood. Do searches to confirm: The Spectrum recievers (all but the BR6000, sold for robotics only) have three states:

1) Startup before the RX finds the TX

CH1 (throttle) outputs no pulses (so ESC won't arm)
CH2 through CHn (n varies by receiver type) output positions "memorized at bind"

2) RX has found TX

All channels output pilot control.

3) RX has lost TX (i.e. failsafe even in progress)

CH1 outputs position "memorized at bind"
CH2 through CHn output "last known good" or "hold" positions, NOT positions memorized at bind.

The BR6000 outputs "memorized at bind" on ALL channels in case (3), otherwise identical.

The DX6 manual is wrong in the way it describes the above; the DX7 manual is closer, but still easy to misread. All of this has been confirmed by physical experementation (and by Paul Beard of Spektrum).

It's easy to prove this to yourself (at least on everything but CH1, which requires a servo tester or similar to see the "no pulse" status). Anway, for CH2 and so forth, just power everything up, move the sticks out of wherever they were when you memorized bind, and turn off the tranny. The controls will hold, they will not move to bind positions; if you have a physical servo (not an ESC) on CH1, you will see it (and it alone) move to bind memorized position.

[DavidH]

Well the pilot told me that it locked out. He was hovering the heli, he switched into idle up and the heli slammed into the ground and beat itself up.
I went down the flight line and asked the pilot what happened. His exact words were that the radio locked out.
The pilot did not dumb thumb the heli. He is also a member here on Helifreak. Where he will say anything about the incident, I don't know.

David

[Danal Estes]

I'm not questioning that the heli did what the pilot said... I'm sure it did. There seem to be documented cases of AR6100s giving non-failsafe, non-bind, i.e. just nutty positions to servos under circumstances that no one has been able to track down (yet). Could have been any number of things from a bad reciever to bad power to ???

One thing it was not: A simple lockout causing controls to go to bind positions. The receivers (other than the BR) just don't do that. Easy to prove to yourself... just do a few experiments with various stick positions and turn the TX off.

So, no need to rebind with pitch in any particular setup.

[DavidH]

This was not a 6 channel rx. It was what ever receiver that comes with the 7 channel radio. Also this is was his first flight with the heli. So I don't think it was a battery problem. The pilot has good mechanicaly ability as he wrenches on a couple of the top pilots helis.
As with any radio control device. Things happen. None of them are immune from things happening.

David

[Danal Estes]

The behaviors described apply to all receivers, AR7000, AR6000, AR6100. Only the BR6000 robotics receiver is different.

And, you are absolutely right! Could have been any number of things... and Spektrums have a failure rate like any other brand. Bummer what happened...


I was posting because the original premise is "re-bind for correct pitch during failsafe" and this is not true. Spektrum failsafe will hold the last known position on all but CH1. Rebind for startup (not failsafe) position changes (like gyro init) and/or failsafe for CH1 only... and anticipate that all other servos will hold.

[Inspector Fuzz]

@Daniel Estes
You are right! I stand corrected. :oops: I think my misunderstanding of this is due to the statement at the bottom of page 19, in the manual, that state "it's important to reprogram the model so that true low throttle and neutral control surface are programmed." Somehow I read past the part on page 18 that states it maintains last commanded control surface position.
Either way, when I initially tested fail safe I must have had the left stick around neutral and when the throttle went to idle I just accepted that everything was right. I just tried it 5 minutes ago and you are correct, if I leave the left stick up, the pitch stays there and the throttle goes to idle when I shut off the transmitter. The DX7 I am using has been working well in a new Stratus.

JEFF

[Finless]

OK correct me if I am wrong but I have TESTED this myself and this is what I found.
The only thing you can SET for a failsafe is throttle (done at bind). All other channels HOLD to what they were at when loss of signal happens.

I have tested this over and over by binding different conditions and powering off the TX. All channels HOLD and only throttle changes ot the condition set at bind.

Bob

[peterob]

OK correct me if I am wrong but I have TESTED this myself and this is what I found.
The only thing you can SET for a failsafe is throttle (done at bind). All other channels HOLD to what they were at when loss of signal happens.

I have tested this over and over by binding different conditions and powering off the TX. All channels HOLD and only throttle changes ot the condition set at bind.

Bob

That's right. As Danal said, the bind conditions for everything except throttle are only used when you power up the RX while the TX is off.

[Rodney]

I dont think that was the first issue he had with the heli, as I think I heard him say the ahad chagned the reciver thinking it might be the probem then it crashed. I have had great luck with mine, sorry Cheif had to be the one with the issues. Maybe we will learn what the problem is soon.

[Jermo]

This was not a 6 channel rx. It was what ever receiver that comes with the 7 channel radio. Also this is was his first flight with the heli. So I don't think it was a battery problem. The pilot has good mechanicaly ability as he wrenches on a couple of the top pilots helis.
As with any radio control device. Things happen. None of them are immune from things happening.

David

David, some vendors have sold the DX7 with the AR6100 reciever. I'm not sure if it's proper but I've read of resellers doing it. So it's possible..
Jermo

[ChiefWilson]

OK as some you may know or may not know I was the one who crashed at Birmingham. I have not said anything about what caused the crash until I found out the truth. Well, after numerous hours on the phone with John Adams (Engineer at Horizon Hobby) I sent my entire and I mean entire electrical system to him for closer inspection. I sent both recievers that I was having problems with, the transmitter, all the servos that were in the machine at the time of crash, 4 new servos for comparison, my 601, my battery, my regulator, like I said everything. So, after my discussions and doing some experimenting on my own this is what I found out. If the radio had simply lost signal it would have gone to failsafe which is hold last position and low throttle. This it did not do. It held last position but never went to idle. So this led me to believe that the radio was not the problem. After sending everything back to John he found that the regulator was the cause of the problem. I have included some pictures of what was found. Keep in mind that this helicopter was crashed 2 weeks before Birmingham when the tail hub sheared off in flight. It was rebuilt and everything tested fine on the bench. As some of you may know I do know how to work on helicopters. Well another thing I found out is when the dx7 and 7000 receiver are linking up the servos will go to the position when they were binded for 1-2 seconds while the link is established. which is low throttle which is also FULL NEGATIVE. Well when the regulator lost power and then the power came back on the servos went to the bind position which is full negative hence the reason that the helicopter went into the ground the way it did. After the crash everything tested fine on the bench. So when binding your reciever I would suggest to hold the bind switch with the left stick centered and as soon as you turn the radio on to bind it flip it into throttle hold. That way you will have all the servos centered and the heli will be in throttle hold when it is establishing a link. Then if for some reason the helicopter loses power and then comes back on the servos will go to the center or zero pitch position instead of full negative. If anyone has any more questions please feel free to pm me about this. So after all this being said it was not the radio or the receivers that caused the problem but an oversight on my part with the first rebuild. under vibration it would lose contact and lose power. I hope this clears the air on this matter. I still fly my DX7 and I am still loving it.

[slikrx]

Chief,
Thanks for the update, and sorry for the crash!
I'm working on switching over to a DX 7 and the occasional problems I heard about made me a bit leery...

Thanks again, and cheers!

[Hughes500Bob]

So does this relate to the AR6100 re-programming that I am having done now at Horizon Hobby .... or is that a different crash scenerio. Thanks for the update! :hug:

[Jermo]

apparently different, TL regulator apparently damaged from a previous crash chose that opportunity to cycle power. Upon re-init of the control system the heli crashed due to startup cycle behavior of the AR7000 reciever.

[Danal Estes]

Thanks for the update ChiefWilson!

[HeliSmith]

Chief,
Thanks for the update, and sorry for the crash!
I'm working on switching over to a DX 7 and the occasional problems I heard about made me a bit leery...

Thanks again, and cheers!

First let me say how sucky it must be to be famous for a crash. If you say Birmingham crash, we know who you mean..

slikrx,

Go with your heart. I wanted to pay less for a radio like the Futaba Faast and every time I went to order it I couldn't click the confirm order button. I ordered the DX7 and I am very happy with it.

I run a simple SportBEC / Phoenix 35 on a 400 class helicopter. The connection is rock solid, the setup was super easy and I feel 100% confident that my connection won't be lost.

HS

[Crash-n-Hard]

Is there a Video of this Crash that made you famous?
Sounds like something i'd like to see. :glasses2:

CNH