Futaba 2.4 Rx

[Kelly]

Found this, does not apply to us at the moment, no summer .

Futaba 2.4 Rx- overheating 

[Tim Mackey]

OK thanks Kelvin...I will sticky this. There was an earlier thread about these and it was suggested that foam should NOT be wrapped around them when installing..... for the same reason

[Lee Burke]

Futaba recommend their 2,4Ghz Rx should not be wrapped in foam and that it be fixed on its edge to expose the largest area possible to ventilation.  They further suggest covering a clear canopy with a cloth or something if the model must be left in the sun.  As they say, there is no problem when the aircraft is flying provided some ventilation has been provided.

Day-time temperatures where I am are in the thirties (celcius) at this time of the year and I just put the aircraft under a bench in the shade when not in use.  In such conditions it would be folly to leave things in the sun for long periods or, worse still, in the car boot .  The covering wilts and ripples in the heat anyway.  As do most of us.

[Steve Murray]

That's a bit worrying. Here in Tenerife the temperature on the flying field can exceed 35 C. I'll just have to remove all the foam wrapping from my Futaba Rxs and maybe suspend them by elastic bands, not that that will be much protection from the shock of my "arrivals"! My Tony Niuhaus Lightening is now 6 inches shorter than it started!

[Chris Dowsett]

Same temperatures here in Spain.  No problems though but then I am being cautious.

If anybody is worried about overheating it should be an easy matter to check out.

The original caution by the way comes from Idris Francis and was recently published on www.aaccmac.org .  Idris is a well respected old time UK R/C manufacturer who used to test fly all gear before he shipped it. He has done some good research on what happens when the 606 receiver is deliberately overheated (with a heat gun).

Idris comprehensively answers "So what do we do to combat this problem?".  Personally I think the first step, if we are flying reliably,  is to check how hot things are getting up there.  If there is enough interest something can be done about it -  there should be enough 2.4GHz fliers around now!  It is not Futaba limited.

[Tim Mackey]

Chris Dowsett wrote (see)

Same temperatures here in Spain.  No problems though but then I am being cautious.

If anybody is worried about overheating it should be an easy matter to check out.

The original caution by the way comes from Idris Francis and was recently published on www.aaccmac.org .  Idris is a well respected old time UK R/C manufacturer who used to test fly all gear before he shipped it. He has done some good research on what happens when the 606 receiver is deliberately overheated (with a heat gun).

Idris comprehensively answers "So what do we do to combat this problem?".  Personally I think the first step, if we are flying reliably,  is to check how hot things are getting up there.  If there is enough interest something can be done about it -  there should be enough 2.4GHz fliers around now!  It is not Futaba limited.

How come ?

[Chris Dowsett]

 Hi Timbo

I will quote Idris.  "...the point I am trying to make is that there is no actual design fault with the RX.  The fact is no modern day digital electronics like to work at excessively high temperatures... "

It is to do with something called Moore's law, how much electronics you can economically squeeze on a chip.  2.4GHz differs from 35MHz more is squeezed on a chip.  It is doing more work and probably running hotter.

Idris has also listed "good practice" which is of general nature.

Kelvin has not highlighted a Futaba RX problem but has drawn our attention to a potential problem for 2.4GHz in general. 

I will do some simple tests of my own and report back when I get a chance.

[Tim Mackey]

Ah Ok ...

[Chris Dowsett]

If anyone wants to worry about "overheating" the technical term is "thermal shutdown".   Try these keywords in Google and see what you get.  There will be the usual brand knocking.

The solution for us (any 2.4GHz) flier is to make sure things do not get too hot.  If you leave your aircraft sitting on the tarmac in hot sun between flights you are really tempting providence. 

My solution will be to stick a temperature indicator label on top of the RX.   I will probably start with one that turns  black at 58degC.   If it never goes black there will not have been a thermal shutdown.  If it does then I will do something about.

All modern digital chips should have some form of thermal shutdown so they are protected from excessively hard treatment.  Ideally going into failsafe and quickly coming back online when they cool down.  I know Futaba's chip has thermal shutdown.  That is a good thing.  Just how well it works I have not a clue!

[Myron Beaumont]

I'm tempted to advise you guys in hot climes to place a solar panel ov er the model to re charge batteries whilst keeping the said model real cool man

[Chris Dowsett]

You are just jealous Myron.

[Trevor Heley]

The original article from Model Flight found by Kevin is not just about temperature. I have had a problem with my unit.

I was flying on 18th Sept when the following happened. Through the previous night I had fully charged my RX & TX. I was in my 3rd fight of the day 2 x 10 mins + say 6 mins when the engine cut out and the plane banked and crashed into the ground. I have a onboard RX voltage meter and prior to take off was in the 5good indicator position [positions are 1Low, 2Low, 3Low, 4good, 5good, 6perfect & 7perfect]. Major damage - wing replacement, fuselage  and stabiliser repair.

On 20th Sept I was flying again to test out after rebuild. Again I fully charged  the RX&TX through the night.
I completed one flight - 10 minutes. On preparing for the second a worrying thing happened. On switching on the RX both the throttle and aileron servos went fully anticlockwise. [The are both set to normal {not reversed} on the TX]. I experimented with switching on/off both the RX&TX. I also manually adjusting the positions of all servos and on RX switch on the rudder and elevator reset to neutral position and the aileron and throttle went to the fully anti-clockwise position! The RX voltage meter was reading 6Perfect. Movement of the right hand stick produced no reaction whereas operating the left hand stick gave expected servo movements for both rudder and elevator. I packed up and went home.
On testing at home I switched on the TX and then the RX - they worked correctly. I will let both batteries discharge some and try again!

I think it is the same intermittent problem that occurred on both the 18th and the 20th. I fly Mode 1 so both the throttle and the ailerons are on the same stick - maybe there is a problem with the stick connections somehow??

My problems were not due to temperature. Anybody got any ideas?

[Former Member]

[This posting has been removed]

[Trevor Heley]

Eric

Thanks for your post.

Yes the  " Futaba 6EX 2.4GHz" transmitter has been exchanged. As I said, the second problem at the field but back at home, without touching anything, it had dissapeared? At home I was hoping to undertake a step by step investigation.

What I can't understand, if it was a loose wire' or similar,  why did it affect 2 servos?On loss of power I would expect the throttle to go fail safe [anticlockwise] on the servo but why did the aileron servo go full anti-clockwise aswell?I have tried operating between the TX and RX as the RX battery has been running down - still operated as expected.

I have sent a E-mail to Ripmax, giving all details, asking for their advice / action. 

Will keep you posted.

[Former Member]

[This posting has been removed]

[Chris Dowsett]

Since you have had a crash Trevor,  it is just possible that you have stripped gears on both throttle and aileron servos.  If you suspect any servo after a crash it is good practice to check the gears or replace the servo.

Have you tried the lower power range test?  This should show up any failsafe/recovery problems 

As you have 2 servos suspect on the same stick and you have already changed the TX the most likely suspect is the new TX.  Ripmax will probably ask to see it.

[Trevor Heley]

Chris - thanks for your post.

The servos are OK. I have had a number of flights since the crash after replacing the RX from another model and using another TX.

I did not try a low power range check. I will rig up for a test but I am not optimistic. On the 2nd problem occasion the model and the TX were within 0.5m.

[Chris Dowsett]

When you do the low power range check try to find out whether the failsafe action you would get is what you are expecting.   You will need to walk out of range and then walk back into range.  That should trigger a loss of signal failsafe.  You could try running a test with a 3 cell RX pack that should make it easier to trigger a battery failsafe (3.5v - not sure what that would be on your RX meter).

 Good luck.  Any response from Ripmax?