Did I Just Imagine That? Or....

[Biggles' Elder Brother - Moderator]

This weekend I went down to the field. I took a low winger with me that is equiped with flaps. The set up is a 2 Aileron 2 Flap arrangement with the ailerons on channels 1 and 6 and the flaps on 7 and 8 (if I remember correctly!). So far, so ordinary - right?

 

Now you might need to know that the gear is Futaba (8FG - 2.4GHz) with an 8 channel receiver and bog standard s3001 servos.

 

I connect everything togther and as usual test the ailerons and flaps before bolting down the wing. Flaps OK. Ailerons - nothing. Mmmmm. So I investigate - maybe I've not pushed the connectors in properly.

 

Ah, well whatever else I've done I have connected the ailerons the wrong way round. Channel 1 should go to the right aileron and its going to the left and vice versa. I know they are the wrong way round because I have little coloured dabs of paint on the connector bodies and they don't match up. So before doing anything else lets put that right. Bingo - working ailerons!

 

Now I didn't think anything more about this at the time - the model is working, the sun's shining I just got on with enjoying myself. Put driving to work this morning I suddenly thought - surely if you connect the ailerons the wrong way round, on a separate channel implementation, the ailerons should still work, but backwards. Surely the system can't "trap" this error. Afterall how can it possibly know the wrong servo is connected on each channel? I'm in work at the moment so can't try this - and tonight I'm busy elsewhere, so I can't easily retest soon. Has anyone any thoughts on this? Do you think it just coincidence that both servos failed to work when connected incorrectly? Or does my Tx/Rx know something I didn't know it knew (IYSWIM)!

 

BEB

Edited By Biggles' Elder Brother on 06/09/2010 11:27:30

[Martin Harris - Moderator]

Are you using Futaba extension leads or "JR" type without orientating lugs?

 

Best guess would be that they were both in upside down - while you're making one mistake why not make another - I know I have!

 

There's no other reason that you wouldn't have seen some response from the servos that I can think of.  Depending of course on the physical layout of the linkages, in most cases the servos will still travel in the correct directions (think Y lead) but may be out of trim.

Edited By Martin Harris on 06/09/2010 13:35:40

[Biggles' Elder Brother - Moderator]

Hi Martin,

 

Good thought that would explain it as of course there would be no power to the servos. But no, they are pucker Futaba leads with the standard wire colour code (white, red and black) complete with the little "tongue" at the side. I'm dying to try it at home and see if I can reproduce the effect.

 

I have been trying to think this out. Obviously with a Y-lead (and assuming the servos are positioned in a "mirror image" it doesn't matter which way round you connect them. But is that still the case when they are are separate channels? Or would they reverse?

 

BEB

Edited By Biggles' Elder Brother on 06/09/2010 13:38:21

[sparks59]

I think you 'nailed it' Martin. plugs in reverse orientation is the most plausible reason for BEB's prob in his eagerness to get some sky under the wings

 

And on a Y lead you would have the same non-working problem. but of course then you can't get them wrong so long as the plugs are the right way for the power / control leads, as your servo throws have to be correctly oriented.

 

On separate channels, it will depend on how you have your servo throws.

 

sparks

Edited By sparks59 on 06/09/2010 14:15:50

Edited By sparks59 on 06/09/2010 14:17:03

Edited By sparks59 on 06/09/2010 14:18:11

[sparks59]

I'm not editing it again!

It could also depend if you are using clockwise and anticlockwise servo's.

[John Privett]

BEB - there is no conceivable way that the radio would "know" the ailerons were plugged-in the wrong way round.  One 3001 looks electrically the same as any other,  and even if servos had some sort of identity (like a GUID?) there's no mechanism for it to be read by the rx...

 

On a typical aileron setup both servos will rotate in the same direction as each other, so accidentally swopping the channels over would keep the correct aileron direction,  though it may muck up throws, centres, differential etc.

[Biggles' Elder Brother - Moderator]

I totally agree John - that's why I am puzzled. I will have some time tonight and I'll connect it all together just to satisfy myself.

 

The lead can't really have been plugged in the wrong way round because they are Futaba and hence "handed". But it just seemed a bit of a coincidence that both should just choose that instant to have a bad connection and not work when they happed to be connected left and right reversed.

 

BEB

[John Privett]

Spooky!

[sparks59]

spooky indeed!

BEB, did you try to plug them the wrong way around, is it possible to sort of 'half engage them' such that you may not have noticed that the plug was not fully home?

Is it possible that they could have been mistakenly plugged into the wrong channel slots on the receiver?

sparks

[Biggles' Elder Brother - Moderator]

I'll experiment tonight to see if its possible to "half engage" them the wrong way round. It can't incorrect rx connection because I never removed any rx plugs and the only "free ones were the flaps and the ailerons and the flaps were working fine.

 

I'll report back later tonight on my experiments!

 

BEB

[sparks59]

So, are your extension leads are universal? ie, without the tab to protect from reversal....all will be revealed later I hope!

[Biggles' Elder Brother - Moderator]

No Sparks - all the leads (servo, extension and those in the rx) are pukka Futaba leads with the blade at the side. That's why I'm doubtful I could have inserted them the wrong way.

 

Only experiment will tell us now I think - roll on tonight!

 

BEB

[Stephen Grigg]

We will all be waiting for the "Punch Line" later BEB

[Biggles' Elder Brother - Moderator]

Well, experiment done!

 

I plugged in the ailerons right way round - everything worked fine.

 

I plugged them in the "wrong" way round - everything work fine!

 

Mmmmm, I can only assume that on Saturday I either didn't shove the leads in far enough or I got them the wrong way in - despite them being Futaba! And amazingly did it on both ailerons on the same occassion having never done it before - weird, but its the only explanation I can come up with.

 

Ah well in one sense a good result - in that at least it all makes sense! Well thanks for all the advice - at least it confirmed I wasn't going bonkers!

 

BEB

Edited By Biggles' Elder Brother on 07/09/2010 22:16:35

[Stephen Grigg]

I think we should be the judge of that BEB

[Biggles' Elder Brother - Moderator]

Ah, how true Stephen, how true!

 

BEB

[John Tee]

I had a similar problem . Right aileron working but not left. on inspection I had plugged the left servo into no5 socket not 6. It was an end pin rx in a tight spot, should have used a short extension lead to make life easier.

 

John