I give up!

[Tim Mackey]

I see we have our grumpy hat back on Myron

PS - stop shouting at your good lady Chrissie, 'tis not her fault your grumpy

[winchweight]

Ok then, the rx will be off to HH today. before posting I conducted 2 more tests. I rigged up a plastic box with lid, packed with polystyrene and rags to insulate it, and popped everything except the motor inside.

This way I hope to recreate an extreme version of the inside of my fuselage with absolutely no ventilation, and all the hot stuff in close proximity.

Timbo, how can I insert a table / chart?

[Myron Beaumont]

Timbo  'tis the only hat I wear these days (and my flying glasses of course  _They work after 20 odd years use

[Ernie]

Hi guys,

I wonder,

First, please don't give up Shaun. You must know that we all break em from time to time.

Now, all I have to add to all this is that each and every time I have a nasty. All the agonising, all the analysis, all the checking, If I am truly honest, show that after all, it was pilot error

ernie 

[Tim Mackey]

Hi Shaun...unfortunately you cant - another on the want list for the tech guys I fear.

At a push you could get the chart up on your screen, use "print screen" button and paste into Paint or similar, then save as a JPEG and insert as picture.

Ernie.... I dont think Shaun has any intention of giving up - and we have pretty much decided that anaysis of the incident reveals some malfunction of something, other than Shaun ! 

[Lee Burke]

Or you could use a little screen capture app like the freeware on this page Link 

[winchweight]

How's this? (Thanks Lee)

The rx remained bound at all times.

The servo fail was due to the connector coming loose.

Motor was too hot to touch

ESC remained cool

UBEC remained cool

Both batteries were comfortably warm to touch

[winchweight]

If nothing else, I proved that these Mystery packs go on for a long time! I'll recharge them later and let you know just how many mah each took.

[Tim Mackey]

There are some things I dont understand here Shaun. Despite the initial pack voltage being the same as the electrolites, the cheaper battery gave significantly less current and power yet at supposedly the same throttle settings. In fact the cheapy pack held better voltage throughout ( no doubt due to the lower current / load  )

I suggest you should do the test with WOT then at least you know you are comparing apples with apples.

Motor obviously stopped due to LVC as it should in run 1

Why did "servo fail" in test 2 ?? We could do with knowing whether the failure was due to loss of signal or loss of power - perhaps you could repeat it with a DVM connected to the servo leads ( use a spare channel to tap into the input volts from the UBEC ) then we could see if the UBEC failed to deliver. 

[Tim Mackey]

Ah.... now you tell me ! you edited your post  whilst I was replying !!

[Lee Burke]

Shaun Chant wrote (see)

If nothing else, I proved that these Mystery packs go on for a long time!

LOL

I guess those are the readings on the lipo.  It would be interesting to see what the UBEC was supplying to the Rx when you operate the servos.  But since nothing failed . . .

[Lee Burke]

Blimey!  You were swift there, Mr T

[winchweight]

Whoa! Now you're stretching my own abilities there guys. I simply took a series of readings with an inline Wattmeter.

As for the 1/2 throttle, the readings I took the other day were taken at WOT and were inconclusive, proving only that the UBEC did it's job and the signal never faultered.

Why 1/2 throttle? I was trying to see if heat was a factor in this, since apparently (see thread on escs) 1/2 throttle generates much more heat than WOT. The box was totally sealed up, packed with foam, polystyrene and old rags to keep the heat in. But nothing happened.

The servo failed because the Y lead connector unfastened, probably due to me pushing it into a hole in the box.

But, now the rx has gone back to HH. So any further tests will only test the remaining hardware, but since the rx has never failed on the deck, I doubt I'd ever prove otherwise.

[winchweight]

Lets be honest, they're both cheapie packs. There was only a couple of quid in it.

Now I look at it, the power differential is quite marked though.

I might rerun it later at WOT and compare it to the earlier test.

Jetsome - when we discussed endurance tests before flying at the field, do you bench run your model at WOT until the LVC shuts down the motor and record the time? Do you then use that as a safe flight time bearing in mind the lower motor loads in flight and the throttle varying throughout? Or do you take a percentage and call that belt and braces?

[Yorkman]

'do you bench run your model at WOT until the LVC shuts down the motor and record the time? Do you then use that as a safe flight time '

well, that's what i do.

And you don't drive about at full throttle the whole time, either. Well, I don't...

[winchweight]

That's pretty much my assumption too. I just wondered if belts 'n' braces came into the equation too.

[scott cuppello]

There is only one way not to suffer brown out's on Spektrum, go 100% OPTO ESC and a UBEC with a 6v output.....before anybody says "I use 4.8v without a problem".....question 1 - And? Why not use 6v, unless you are using JR digital servo's? . May I also point out that I also know people using 4.8v with Spektrum on large turbines, etc......except they are using massive 2s Lipo's with mega expensive regulators....not quite the same thing.

Electric models are the ones that have suffered the most with brown out problems, and it's all down to voltage problems, the motor cutting out [the first sign] is the RX going into failsafe....caused by a brown out...caused by low voltage. I see that this happened on a Sea Fury...what, 6 servo's? BEC/ESC's are just not up to it....regardless of what may be claimed by the manufacturer.

I can afford to run even the parkfly Spektrum recievers now with good range....on 6v....it's required a re-think until somebody brings out an ESC with a built in SBEC with 6v output.....that's the only configuration I will use.....2.4ghz now wonderful!

[winchweight]

Hi Scott.

I was running a BEC on the first crash, but this time I had a 60a OPTO esc and a U-BEC (granted it was a 5v unit). However I have just ordered a few 6v U-BECs and will retro fit them to all my leccy models.

Of note though, the battery only took 400mah on charge immediately after the crash, so it is unlikely that the voltage dropped enough, surely. It is a 25C - 30C 2200mAh battery after all. Or then again maybe not.... maybe it could.

[Alan B]

Hi Shaun

Sorry about the model   Just as a matter of interest for all spektrum users.  On Sunday I was doing a range test prior to flying my model.  I had the transmitter pointing ( DX - 7) directly at the model.  I pushed in the range/bind button - No response - Released the button for full transmission  - no response.  It was then I realised the TX Antenna was straight.  I bent the Antenna up as I would normally have it - Did the checks again - perfect  - straightened the Antenna again pointing at the model  -  Nothing.

As far as I know it makes no mention of Antenna positioning in the Spektrum instructions. All it says is Do not point the TX Antenna directly at the model. The radiation pattern from the tip of the Antenna is inherently low.

I have seen photos in the past of spektrum users using their TXs  with the Antenna straight -  they are in my opinion asking for trouble. Probably nothing to do with your problem Shaun but I thought it was worth a mention

Al

[Piper Cub]

Hmmm. All this is vert disheartening not to mention the loss of  your plane.

I know perhaps many leccie planes are restricted for internal space or, there is the aversion of carrying extra weight but, surely it would be best practice to use a separate battery pack for receiver and servos?

[scott cuppello]

The antenna should be pointed at around 30 degrees so it's straight up when the radio is around 45 degrees....we found this using a "glitch counter".

 You really need to fit 6v UBEC's, the fact is that brown out occurs at 4.7v....not 3.5v as people seem to believe.

It stands to reason that a 5v BEC or a 4.8v RX pack has NO headroom, brown out's are not caused by some catastrophic loss in battery strength, rather it's a glitch, a voltage spike, which can be caused by almost anything....don't forget, you are relying on the accuracy [to 0.3-4 of a volt!] of an electrical device....not satisfactory.....chances are, the BEC dropped voltage for a second....in fact I will guarantee it.....6v BEC required 3-5A version.

 6V output simply means you will never get close to 4.7v without s severe overload somewhere [stalled servo perhaps]....which would potentially bring down any model, regardless of 2.4ghz or 35mghz.

[Alan B]

Hi Jetsome

I agree it does make theoretical sense.  However if the antenna is supposed to be straight then why have Spektrum jointed the antenna?     The strange thing is when I first bought the Spektrum  I used to fly with the antenna straight - I did have a loss of control a couple of times.  It was when the model was flying directly in front of me. I must have been pointing at the model without realising it.  Ever since I have now got into the habit of bending the antenna - I have never had any problems since.

Al

[Frank Skilbeck]

Scott, I've been flying for many years and we used to use 600 mah 4.8v Rx batteries without much problems , admittedly on 35 mhz.

I've got 3 spekky set ups 1 6200 and 2 6100's all running off a 3s lipo and ESC standard BEC set up, the 6200 uses 4 servo's and I've not had any problems, these are all 5v BEC's

I have another 4s lipo powered 6 servo plane on 35 mhz (Multiplex IPD) with an ESC with a built in SBEC again no problems and I've monitored the temp of the ESC which is in fuselage in flight with my e-logger and there is only a moderate temp rise after a 8-9 min flight (see below) so it's not being stressed.

I don't think a 5v is a problem here unless there is another connection problem.

This is also taken from the Spektrum web page

"With all radio installations it is vital the onboard power system provides adequate power of 4.5 volts or more without interruption to the receiver even when the system is fully loaded (servos at maximum flight loads). This becomes especially critical with giant scale models that utilize multiple high torque/ high current servos. Inadequate power systems that are unable to provide the necessary minimum voltage to the receiver during flight loads have become the number one cause of in flight failures. Some of the power system components that affect the ability to properly deliver adequate power include: the selected receiver battery pack (number of cells, capacity, cell type, state of charge), switch harness, battery leads, regulator (if used), power bus (if used).

While Spektrum’s receivers’ minimum operational voltage is 3.5 volts, it is highly recommended the system be tested per the guidelines below to a minimum acceptable voltage of 4.8 volts during ground testing. This will provide head room to compensate for battery discharging or if the actual flight loads are greater than the ground test loads."

So brown out doesn't occur until 3.5v also if Shaun had the latest Rx firmware the reconnect time is pretty quick in the event of an intermittent loss of power.

[Tim Mackey]

Scott Cuppello wrote (see)

There is only one way not to suffer brown out's on Spektrum, go 100% OPTO ESC and a UBEC with a 6v output.....before anybody says "I use 4.8v without a problem".....question 1 - And? Why not use 6v, unless you are using JR digital servo's? . May I also point out that I also know people using 4.8v with Spektrum on large turbines, etc......except they are using massive 2s Lipo's with mega expensive regulators....not quite the same thing.

Electric models are the ones that have suffered the most with brown out problems, and it's all down to voltage problems, the motor cutting out [the first sign] is the RX going into failsafe....caused by a brown out...caused by low voltage. I see that this happened on a Sea Fury...what, 6 servo's? BEC/ESC's are just not up to it....regardless of what may be claimed by the manufacturer.

I can afford to run even the parkfly Spektrum recievers now with good range....on 6v....it's required a re-think until somebody brings out an ESC with a built in SBEC with 6v output.....that's the only configuration I will use.....2.4ghz now wonderful!

I am sorry Scott but I must disagree with you my friend

1) To state that the ONLY way to not suffer a brown out with Spektrum is to use opto isolation and a 6V UBEC is simply wrong.

2) Your second staement is also wrong - you say and I quote - "its all down to voltage problems, the motor cutting out ( first sign) is the RX going into failsafe...caused by a brown out "..... etc etc. Wrong again

On the first statement let me expand. I AM GOING TO SAY I use 4.8V with no problem .....because I do!

I do operate most of my stuff on 6V via LiPo and regulator, or UBEC because I DO agree with you that this is the safest and best method...however, 3 of my small foam models use a simple and cheap non opto ESC with inbult simple linear 5V BECs. One of these is my very well used and faultlessly performing ALFA Sabre, which on Sunday flew its celebratory 100th flight at Roodee. The other two have also had probably 50 flights or more between them and again not a single issue. Ever. This I am afraid makes statement No1 simply wrong.

On the second issue I offer the following explanation.. The receiver will NOT enter failsafe and therefore close the throttle due to a brown out. The only time the receiver engages failsafe is through loss of both signals being received from itsTx. The ESC also may shut down the throttle if it detects signal loss. The result of a brown out is loss of control of any and all servos and rapid flickering of the rcvr LED, usually followed by control restoration as the falling load allows voltage to momentarily rise sufficiently...albeit for a brief microsecond until the whole cycle repeats itself. The only other way in which the motor will cut out is if the ESC LVC activates due to low battery ( which again will NOT cause brown out in correctly set ESCs ) or of course if the motor itself should fail.

I have just uploaded a very short video demonstrating these points and the link will be live very very soon.

[Tim Mackey]

Alan B wrote (see)

Hi Shaun

Sorry about the model   Just as a matter of interest for all spektrum users.  On Sunday I was doing a range test prior to flying my model.  I had the transmitter pointing ( DX - 7) directly at the model.  I pushed in the range/bind button - No response - Released the button for full transmission  - no response.  It was then I realised the TX Antenna was straight.  I bent the Antenna up as I would normally have it - Did the checks again - perfect  - straightened the Antenna again pointing at the model  -  Nothing.

As far as I know it makes no mention of Antenna positioning in the Spektrum instructions. All it says is Do not point the TX Antenna directly at the model. The radiation pattern from the tip of the Antenna is inherently low.

I have seen photos in the past of spektrum users using their TXs  with the Antenna straight -  they are in my opinion asking for trouble. Probably nothing to do with your problem Shaun but I thought it was worth a mention

Al

Alan. I have posted several times in several different threads as to the correct antenna orientation. I NEVER fly with the aerial straight, as I tend ( as most pilots do I suspect ) to hold the tx fairly flat and having the aerial angled via the purpose designed "knuckle" joint ensures the aerial is at pretty much right angles to the model and never pointing straight at it.