Electric flight safety logic

[Dave Hopkin]

Posted by Martin Harris on 21/02/2016 13:57:05:

...as, I assume, was Chris's!

I dont know if he was joking or serious - I do know that some newbie might read it and think its a good idea....

As Stuart points out the weakest link in the train is the squidgy organic thing holding the TX - which is why I try hard to have a fixed procedure I run through regardless of model and the appropriate level of protection for myself and others

[Biggles' Elder Brother - Moderator]

I think Dave and Martin are making very good points about consistency. I have the "Sticky T-Cut" set exactly the same on every model; same switch, same orientation, same voice alarm. That way I encourage a safe application of the "soft squidgey thing" to maximise consistent safe practice. I have flown other people's models where it sometimes seems to me that what switch and what orientation of the switch cut the throttle was an "on the spur of the moment decision " when they set the model up and is different model-to-model. Personally I feel that is very bad practice and possibly potentially more dangerous than having no cut at all.

Regarding Andy48's question on how can you disable a throttle cut in flight so that it cannot be accidentally activated well (I've not done this!) but it should be possible on Taranis to simply build another layer on the logic of Sticky-T-cut" that depended on the variometer altitude reading being signicantly higher than its initialisation value. I might have a go at that to see if it works - but on something i don't mind dropping from 20 feet!

BEB

[Andy48]

That requires a variometer each time you fly. Had thought of that as one solution, but is there another way without requiring that? One way I presume would be to also use the unused throttle trim, and combine that with a motor cut switch, so that once the motor cut switch is enabled, the throttle trim is set to centre, and then only allow the motor cut switch to be disabled after the throttle trim has been changed again manually. i.e. two switches are used for the motor cut, with a voice alert to confirm.

I still believe the safest way of all is an arming plug that is inserted only once the model is carried out and placed on the flight line, and removed after flight whilst still on the flight line.

Edited By Andy48 on 21/02/2016 19:27:42

[Frank Skilbeck]

Posted by Andy48 on 21/02/2016 19:27:08:

That requires a variometer each time you fly. Had thought of that as one solution, but is there another way without requiring that? One way I presume would be to also use the unused throttle trim, and combine that with a motor cut switch, so that once the motor cut switch is enabled, the throttle trim is set to centre, and then only allow the motor cut switch to be disabled after the throttle trim has been changed again manually. i.e. two switches are used for the motor cut, with a voice alert to confirm.

I still believe the safest way of all is an arming plug that is inserted only once the model is carried out and placed on the flight line, and removed after flight whilst still on the flight line.

Edited By Andy48 on 21/02/2016 19:27:42

Must admit I've never hit my throttle cut switch while the model is in the air, but activate throttle cut as soon as the plane is down so it can be safely picked up. But some ESCs can be equipped with a suitable safety plug, like this, but you don't find these at the budget end.

[Fatscoleymo]

Ya can program Taranis (and my buddy has it on his DX9) for throttle cut to activate only if throttle is less than 10% - or whatever value you care to input, maybe just the last 5% where trim operates... or whatever..

Then when flying using normal throttle inputs no chance of accidently switching off....

I use it on all my IC planes.

Fats

[Geoff S]

Posted by Frank Skilbeck on 21/02/2016 19:42:39:

Must admit I've never hit my throttle cut switch while the model is in the air, but activate throttle cut as soon as the plane is down so it can be safely picked up. But some ESCs can be equipped with a suitable safety plug, like this, but you don't find these at the budget end.

Well, not actually in flight but after launching my Phoenix 2k with my right hand I inadvertently caught the motor kill switch as I returned it to the transmitter Nothing much happened except the plane gently landed a few feet in front of me.

On my Taranis I use the RH switch on top of the case (whichever that is, I haven't got my transmitter handy) as motor disabler together with a voice warning. I can't see my ever switching it off in actual flight and even if I did most often it wouldn't be a total disaster and easily corrected.

I'll certainly look into the sticky throttle option though.

Geoff

[Dave Hopkin]

Posted by Andy48 on 21/02/2016 19:27:08:

That requires a variometer each time you fly. Had thought of that as one solution, but is there another way without requiring that? One way I presume would be to also use the unused throttle trim, and combine that with a motor cut switch, so that once the motor cut switch is enabled, the throttle trim is set to centre, and then only allow the motor cut switch to be disabled after the throttle trim has been changed again manually. i.e. two switches are used for the motor cut, with a voice alert to confirm.

I still believe the safest way of all is an arming plug that is inserted only once the model is carried out and placed on the flight line, and removed after flight whilst still on the flight line.

Edited By Andy48 on 21/02/2016 19:27:42

If you do accidently hit the throttle kill switch in flight, then its just a question of hitting it again, bringing the throttle to zero and then throttle up again - the beauty of electric!

Edited By Dave Hopkin on 21/02/2016 20:07:29

[Andy48]

Posted by Fatscoleymo on 21/02/2016 19:55:39:

Ya can program Taranis (and my buddy has it on his DX9) for throttle cut to activate only if throttle is less than 10% - or whatever value you care to input, maybe just the last 5% where trim operates... or whatever..

Then when flying using normal throttle inputs no chance of accidently switching off....

I use it on all my IC planes.

Fats

Yes that is easy on the Taranis, but how do you prevent this switch accidentally being activated when the throttle is zero and the model is still flying.

[Chris Barlow]

Posted by Dave Hopkin on 21/02/2016 14:05:51:

Posted by Martin Harris on 21/02/2016 13:57:05:

...as, I assume, was Chris's!

I dont know if he was joking or serious - I do know that some newbie might read it and think its a good idea....

No Dave not even joking or serious. I definitely wouldn't recommend it! I see what you mean about a complete novice flying on their own but I doubt anybody would be stupid enough to actually try it? (I may be wrong...)

On another note to a hypothetical idea maybe it's the electric model design that would be wrong. After all when an i.c engine is started you wouldn't want to get close to the prop arc to remove a stubborn glow stick. You'd fit a remote glow port instead.

At the end of the day as said many times before in many threads electric models should be treated the same as i.c models once live, even if the prop isn't turning!

[Dave Hopkin]

I agree about the treating it in the same way as a running IC engine when the Lipo is connected. but the issue here is that unlike a tank, a lipo has to be physically removed for charging - so as its usually the single heaviest lump in the airframe so on short nosed models like radial biplanes frequently it has to be immediately behind the prop arc and short of a church roof in the cowl there isnt a lot of scope for design changes

[Barry Pickering]

After accidently knocking the safety switch I was using and the throttle lever together causing the motor to start I decided I needed a more fool proof method. What I came up with and what I use on all my gliders is the use the S1 switch on my Taranis. In the logic screen I program a logic switch so that S1 has to be more than Zero to be turned on, then in the function screen using that logic switch, if it turned off then the throttle switch is overridden to -100. So before starting a flight the S1 switch is turn passed Zero and before collecting the model after landing the S1 switch is turn fully to the left (-100).

[Chris Barlow]

The problem isn't inserting or removing the battery but where the connection from battery to ESC is made.

Back to the original question though, aside from specific programming of an open source TX the safest way to prevent a sudden start up of an electric motor is still to treat it as a running i.c engine and keep it restrained until takeoff and keep anything valuable out of the prop arc!

Any other system or safety device should be considered secondary to this, not an alternative!

 

Edited By Chris Barlow on 21/02/2016 20:27:56

[Biggles' Elder Brother - Moderator]

I don't think anyone is suggesting otherwise Chris. What I think is being proposed and illustrated are the additional protections that can be incorporated for added safety on that one occassion when you forget the "primary directive" which of course we are capable of doing!

BEB

[Joe Beavis]

All this switch stuff is too clever for me - I drilled two holes in the bezel of my transmitter, so that an 'R' clip (made from a coathanger) passes across in front of the throttle. This allows testing of all controls EXCEPT the throttle. I carry the model out, remove the pin, fly the model, and as I go to fetch the wreckage I replace the pin, which hangs on a string. The beauty of this system is that everybody else can see that my throttle is safe from yards away.

[Geoff S]

Posted by Chris Barlow on 21/02/2016 13:30:41:

I think it was Damon Hill who said to slow the formula one cars down and make them safer just take away the seat belts!

A similar idea was suggested by TE Lawrence (of Arabia) who was a very keen motor cyclist and rode an SS100 Brough Superior. His idea was that all motorists should drive with the point of a spear resting on their chest with its shaft fixed to the front bumper.

Geoff

[Fatscoleymo]

..........'Yes that is easy on the Taranis, but how do you prevent this switch accidentally being activated when the throttle is zero and the model is still flying.......'

Ok then, use two switches.....each on opposite sides on the tranny....or deadstick.....

Fats...

[Tony Smith 7]

Posted by Dave Hopkin on 21/02/2016 12:31:35:

Couldn't agree more Martin - I use the Taranis Sticky Throttle set up, and have voice actication on the throttle kill switch - I also use the following power up sequence

1) Turn on TX (but DONT acknowledge the switch position warning screen

2) Plug in Lipo

3) Acknowledge the Switch warning on the TX (meaning I am clear of the model and its restrained)

4) ESC Arms and Servos power up

...

I don't know the Taranis, but I think with my 9X using OpenTX software the radio isn't transmitting while the switch warnings are shown. If that's the case then I think this sequence is exactly equivalent to connecting the LIPO before switching on the transmitter.

[Biggles' Elder Brother - Moderator]

As a taranis user I think you are correct Tony, if you ignore switch warnings (ie switches not in the position you have nominated at power up) then the taranis does not transmit. That is certainly my understanding. What I do is programme to require the throttle cut switch to be in the disarmed position on power up I then correct any other switches to be sure that the Tx is actually transmitting, and only then proceed to battery connection.

BEB

[Dave Hopkin]

Posted by Biggles' Elder Brother - Moderator on 22/02/2016 13:46:38:

As a taranis user I think you are correct Tony, if you ignore switch warnings (ie switches not in the position you have nominated at power up) then the taranis does not transmit. That is certainly my understanding. What I do is programme to require the throttle cut switch to be in the disarmed position on power up I then correct any other switches to be sure that the Tx is actually transmitting, and only then proceed to battery connection.

BEB

I would concur because the the ESC does not even give the cell count beeps until the switch warning has been gone through - so its totally disarmed regardless of stick / switch positions

[John F]

With all the switches to activate there is still the possibility, albeit microscopic, that the the motor will spin irrespective.

Would it not be best to adopt a KISS solution and have an arming plug?

[Martin Harris - Moderator]

...until that day when your routine is interrupted and the arming plug wasn't removed - or a "helpful" soul sees it lying by the model and pops it in so you don't lose it, or one of many unimagined scenarios takes place.

In my book, there can be no substitute for keeping clear of the prop arc and possible model trajectory at all times. If it is physically impossible to connect the battery without putting yourself in harm's way, shouldn't you be redesigning your installation?

[MattyB]

Posted by Andy48 on 21/02/2016 14:04:04:

A motor kill switch is a good idea, BUT how does one design a kill switch that

a) can't switch the motor off when in flight under any circumstances

b) will switch off the motor when the flight ends.

I have another solution for this one... Last year I created some "Unknockable" safety switches for the ignition system and retracts on my Dad's new petrol engine Spitfire. These utilise a three position switch, and require a specific sequence of moves that include a to change of direction be made within a given timeframe in order for the function to be activated, thus meaning any accidental move of the switch does not cause anything to happen:

The example EEPE and documentation is available on RCSettings - just make this the input to a sticky throttle cut and you have a very safe, resilient system. Full description below...

"A novel safety switch which if accidentally knocked will not change state. It can be used with any three position switch, and requires that a sequence be completed that includes change in direction of the physical switch within a given time period to activate/deactivate the desired function.

These switches are ideal for complex IC models with retracts and ignition systems where accidental activation could cause injury or damage to the model. They can also be used as throttle kills on electric fixed wing and rotary craft.

 

Switch Descriptions

General

• Each switch is configured by default to require the activation/deactivation sequence to be completed within 5 seconds.
• If the sequence is not completed within the time it deactivates and the switch must be returned to its original starting position before another attempt can be made.
• I have chosen 5 seconds as this makes testing in OpenTX Companion easier, but I recommend shortening the time period to somewhere between 1 and 2 seconds when used on the real model to make accidental activation even less likely.
  • To achieve this alter the “Duration” parameter against the relevant logical switches (L1 & L2, L8 & L9, L15 & L16) to the desired time period in seconds.

 

Switch 1 – Throttle Kill

• Activated by physical switch SG (sequence must complete within 5s).
• Defined by logical switches L1-L6.
• Switch active only in Takeoff (FM0) and Landing (FM2) flight modes:
  • To be switchable in ALL flight modes, eliminate the !SE- condition in L3 and L5;
  • To be switchable in only one flight mode, replace !SE- in L3 and L5 with FMx (where x is your desired flight mode number).

 

Switch 2 – Ignition

• Activated by physical switch SD (sequence must complete within 5s).
• Switch active only in Takeoff (FM0) and Landing (FM2) flight modes.
  • To be switchable in ALL flight modes, eliminate the !SE- condition in L10 and L12;
  • To be switchable in only one flight mode, replace !SE- in L10 and L12 with FMx (where x is your desired flight mode number).

 

Switch 3 – Gear

• Activated by physical switch SB (sequence must complete within 5s).
• Defined by logical switches L15-L19.
• Switch active in ALL flight modes.
  • For description of how to make active in a single/subset of flight modes, see switches 1 & 2.
• Gear delayed by 3 seconds to enable rapid cancellation if Gear slowed by 3 seconds for scale effect (was designed for my Dad’s Spitfire!)

All functions of state are confirmed verbally when activated, and the sound files are attached with the ZIP file – simply paste them into the Sounds folder on your Taranis."

Edited By MattyB on 22/02/2016 17:15:54

Edited By MattyB on 22/02/2016 17:16:32

[MattyB]

PS - Despite having created the item above, I also agree with the views expressed by a number of posters; no automation is a complete replacement for common sense operating practices like tethering and treating models as live as soon as the battery is plugged in. Isn't it nice though that we can all create these additional safety solutions for ourselves using open source firmware? I definitely don't look back fondly to the days of having to use whatever the software engineer at Futaba, Spek, JR etc decided was the "correct" switch and functionality for a throttle cut!

Edited By MattyB on 22/02/2016 17:14:55

[Andy48]

Posted by Martin Harris on 22/02/2016 15:24:29:

...until that day when your routine is interrupted and the arming plug wasn't removed - or a "helpful" soul sees it lying by the model and pops it in so you don't lose it, or one of many unimagined scenarios takes place.

In my book, there can be no substitute for keeping clear of the prop arc and possible model trajectory at all times. If it is physically impossible to connect the battery without putting yourself in harm's way, shouldn't you be redesigning your installation?

I clip the arming plug onto my tx neck strap, its never left on the ground.

On the unimagined scenarios, there are an equal number when keeping clear of the prop arc can fail as well.

Edited By Andy48 on 22/02/2016 17:36:38

[Andy48]

Matty, that's a brilliant solution, you certainly get the brownie points for it!

While I generally use an arming plug, I have a couple of small foamy models that it is just not practical to have an arming plug fitted, and then I use a kill switch. Back to the Companion for a few mods!

You're right about both the open source software and common sense.