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2.4 fail safe function


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Posted by Martin Harris on 26/04/2011 01:13:24:
Tom - not really sure what you're asking but it's unlikely that a model in failsafe would survive unscathed in the event of total lockout. The point is to minimise the chances of interfering with any air traffic (as it should be at least 100 feet above you) by closing a throttle or deploying airbrakes/crow flaps etc.
 
There has been a lot of debate about the positioning of control surfaces in failsafe but I'd consider a stalled airframe crashing on or close to a model flying field to be potentially less hazardous than one disappearing uncontrolled in the direction of habitation, roads or livestock.

Edited By Martin Harris on 26/04/2011 01:14:06

Spot on Martin, that is my understanding, no "yes buts...", "ah buts"... or "but" ...anything - in the event of loss of control the overriding factor is to prevent a fly away (which could be to altitude as well as distance). Safety Vs Saving the model, no contest.
 
Ian
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Posted by Phil B on 25/04/2011 23:59:56:
I would say that alot of them on 2.4 would be set as it is set during binding and the tx (I would imagine) most will have the throttle set to low even if they were not aware it should be.

but maybe more should be done to make people aware. could a fail safe demonstration be a compulsory part of the A test?
 
 

Edited By Phil B on 26/04/2011 00:00:32

Exactly. It appears to be inherent in the design of the binding process in at least the major 2.4GHz systems that the failsafe is set during that binding process and will have the throttle set to low.

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Posted by leccyflyer on 26/04/2011 16:07:20:
Posted by Phil B on 25/04/2011 23:59:56:
I would say that alot of them on 2.4 would be set as it is set during binding and the tx (I would imagine) most will have the throttle set to low even if they were not aware it should be.

but maybe more should be done to make people aware. could a fail safe demonstration be a compulsory part of the A test?
 
 

Edited By Phil B on 26/04/2011 00:00:32

Exactly. It appears to be inherent in the design of the binding process in at least the major 2.4GHz systems that the failsafe is set during that binding process and will have the throttle set to low.

This may be okay for electric aircraft on transmitters that set the failsafe this way (not all the major ones do - the popular Futaba 6EX range being an example that does not and Hitec Spectra/optima sets being another) however there's more than one way to power an aircraft.
 
IC engines need to have their idle set after initial binding and it's important to then rebind the the system to set the failsafe correctly( for example see Spektrum DX6i manual, p19 para No.6) .
 
It's not just IC aircraft that can have issues, there's gliders and the such like where it might be prudent to set the control surfaces to cause the aircraft to enter a descending circle - the Smartsafe type of system doesn't seem to allow this as it moves all surfaces to the neutral position.
 
Ian
 

Edited By Ian Jones on 26/04/2011 17:03:15

Edited By Ian Jones on 26/04/2011 17:03:58

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Posted by Phil B on 26/04/2011 00:51:06:
Boggy I think the original point was they are not being set because people are not fully aware of them not because they where ignoring them
 
 
I THANKYOW, it is indeed as Phil B states, but now the initial foray into setting is delt with, its interesting that the old arguments about just how to set it are coming into play, on my 2.4recievers, on some, its only possible to set the throttle, on my R900s, its possible to set all functions, this is my reciever of choice for my bigger models,
 
as for what settings to use, this is up to the individual, but for me, the primary care is to stop the errant model getting into restricted airspace, I.E. where the big boys fly, dont forget, it may be possible to fly out of the errant danger, control may be resumed, you also have to bear in mind that the attitude of the model has to be taken into context, if a 40% extra, with a DA 150 was set to full up, and hard over, what would happen if it was ding a low invertes run? answer is, flick into an active crowd line, or worse, i have had this rather heated argument with non other than Dave Boddington hiself, the model has to be kept down, but the chance of saving a bad crash is far better than the chance of injury from such a crash,
 
as for the its not legal thing---well, sorry, its a CAA mandate, not a BMFA one, i would not go there when its just simpler to set the thing,
 
and lets not forget why this mandate came in, the death of 11 yr old Adam Kirby, struck by a model when the frequency control was being abused, and a model with unset PCM rx sent the model into the pits, model went into last input signal, in this case one of those was full throttle, had the throttle been set to low, the model would have been in the floor well before it got to the pits area,
 
so SET the thing
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Martin and Ian .
The other dimension to this discussion,is the necessity to ensure a potential fly away situation not only removes risk of conflicting with full size traffic,but also to prevent the risk of a model getting far enough away to end up in a populated area ,on a road,or , any other location that involved risk to persons property or animals.
Surly best possible fail safe compliance would have to involve an assessment of ....,type of model, wing loading,stability characteristics,wind direction,flying site lay out ,and proximity of no go areas.As many of these factors are variable,and with different flying sites all the factors could be variable,do we think Mr average RC flyer,does make the appropriate assessments,and then converts them into a fail safe programme?
TW2.
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I completely agree with TW2 and to answer Tom's final point no I don't think Mr Average does. Lots of reasons for that:
* "flying for xx years without a failsafe so why use one now",
* "it's preset so that will do",
* apathy,
* not enough noise made about the importance of setting failsafes (thankfully we seem to be doing something positive about that),
*surprisingly, some people still don't even know they have got a failsafe let alone what to do with it,
* not setting the failsafe will not make the aircraft crash so it's possible not to consider the issue until after an incident has occurred,
* "just another rule that we don't need. ",
* the above being inherited by more recent entrants in RC flying,
 
So I think Mr Average could do it but I doubt that he does.
 
Ian
 

Edited By Ian Jones on 26/04/2011 18:51:29

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Posted by tom wright 2 on 26/04/2011 17:38:41:
Martin and Ian .
The other dimension to this discussion,is the necessity to ensure a potential fly away situation not only removes risk of conflicting with full size traffic,but also to prevent the risk of a model getting far enough away to end up in a populated area ,on a road,or , any other location that involved risk to persons property or animals.
Surly best possible fail safe compliance would have to involve an assessment of ....,type of model, wing loading,stability characteristics,wind direction,flying site lay out ,and proximity of no go areas.As many of these factors are variable,and with different flying sites all the factors could be variable,do we think Mr average RC flyer,does make the appropriate assessments,and then converts them into a fail safe programme?
TW2.
Tom, a flyaway state indicates that the model has not lost signal, but battery power, if it flys away, then no failsafe on earth will bring it down, if the fails safe is set to at least throttle down, then there is no chance of a flyaway situation, the model just comes down, size, type, wingloading or whatever does just does not come into it,
 
the CAA mandate is to stop an errant model from entering air lanes, the absolute minimum it requires, by law is throttle to idle, or closed for electric, there is no need to go mad with it,

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Allan .
Sorry i can not agree,this discussion amounts to the degree of awareness, or not , present in the mind of the average model pilot.
Irrespective of fail safe settings a lack of awareness along the lines i suggest,is in my view dangerous.Rather than "going mad" its just plain common sense.
To quote from your post,"if the fail safe is set to at least throttle down,then there is no chance of a flyaway"...........Not so! i have seen 4m EP gliders end up miles from the field following loss of signal / battery power,the motor shuts down and at the moment of failure the control surfaces remain at best LD setting,resulting in an uncontrolled long distance fly away,this situation confirms that a greater awareness, and more than minimum fail safe would be a sensible idea.This situation was recently highlighted when a well known TX just stopped transmitting the model in this case was an Extra ,the motor stopped and the model flew away in a dead strait line and came down in a public area over half a mile away.I think the whole subject requires a great deal of thought ,and there is no place for apathy.
 
Tom.
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