DX8 owners thread...

[NigelH]

Posted by Chris Bott on 19/08/2011 22:35:24:

 

If it's an issue that Andy is working on he will be very interested in your results...

I had an issue with flaps operating elevator in an unwanted way, but only if i had a lot of elevator trim in. They cured that after I brought it up..

 

 

 

 

Interesting. I've had issues this week with the flap system.

 

In my case though, I'd set up the left hand wing and all was good but when I set up the right flap, things were not right. By chance, I noticed that the elevator stick influenced the flap position. I looked at the monitor screen and discovered that (only) the right flap was somehow mixed in with the elevator.

 

Andy suggested a couple of things. I was sure that I'd got it right but checked anyway. All ok. The really odd thing though is after the checks and with NO changes, the elevator to right flap mix had gone.

 

He's added this into their issues list and said that as the elevon trim issue research is in the flap system code, a cause for this problem may also be found.

 

[Chris Bott - Moderator]

OK throttle cut for electrics - I said I'd explain.

 

This may be old hat for some but new to others.

With an electric model you may want a switch that allows you to prevent the motor running if you accidentally move the throttle stick. (Maybe while you test other channels or take the model out to the strip)

This can easily be achieved with a throttle cut function, however on an I/C this would normally move the a throttle servo from tickover to a lower position.

If we do this on an electric model it will work, but can cause us problems with the majority of ESC's.

This is because they tend to take the first throttle position they see after switch on, as the low throttle position. So it will make a difference which position our throttle cut switch is in when we arm our model. If we arm in the tickover position all will be well. If we arm in the "cut" position, the ESC can arm and as soon as we switch to "tickover" the prop starts whizzing round and we can't stop it with the throttle stick...

 

OK here's the trick. To give us a switch that does what we expect, on the DX8 we have to set the throttle cut position as a percentage (i.e. the servo position in cut mode) to somewhere around 30%. This gives us no movement between when the switch is operated, so it doesn't matter where it is when we arm. Ideally we need to check on the monitor screen that there's no movement, and adjust that percentage slightly if there is.

 

That's a long explanation for a simple setting, I do hope it makes sense?

[Chris Bott - Moderator]

PS I've assigned mine to the Mix switch as it's well out of the way, and I have it set so if the switch gets knocked when I put the Tx down, it cut's the throttle.

[Tim Mackey]

The elevon trim reverse bug is now mentioned on the spektrum DX8 community site.

I noticed that when I visited earlier today, a headline claimed...

" You have new content available for your Radio"

Well I havent, 'cos all thats showing is the 2.03 BETA which I already installed a week or so ago - and which showed up the elevon trim reverse problem in the first place

The site is specific to the registered radio, and should know which version of the software was last loaded, so why is it proclaiming new content is available?

 

Right...couple more items for you DX8 users.

I have been using the RC Groups thread ( big ) to discuss some issues, so will summarize them here.

 

1) You need to be at least 2 metres away from the Rx when binding.

 

2) If you select the flight mode switch to operate flaps ( which is an option available ) then any "warning" applied will not work on that switch...but still works on the now unused flap switch. Dumb IMO

 

3) The best method of expanding the model memory beyond 30 seems to be to leave slot 30 free. Store your 29 other models on 1 - 29 and put the rest ( 30 onwards ) onto an SD card. If you require to use one these, load it from the card into mem slot 30.

REMEMBER any such model will need to be bound each and every time its entered from the card into mem slot 30.

This also applies if you move a model from one memory to another.,

I am going to fit a short extension lead to facilitate easy binding on any of these "extra" models.

 

4) Trainer Modes. The various options can be a little confusing, so I queried a typical example as follows. "

"A club instructor has a DX8 with all 30 memories occupied. A pupil turns up with a model, already bound to his DX6i ( or 7 ).

Rebinding is difficult due to receiver location, and besides... its his model on his tx, and he may want to fly on his own sometimes. Whats the best way to set up instruction?"

 

Answer from Andy Kunz ....

" For the DX6i I think the only option is "Normal" mode, where all the PPM data comes from the slave and goes out the RF. You will have to set your DX8 to the Slave function and do all the programming to match the DX6i's. Before you do that, save any model slot used to SD card. (BTW, on my radio Model 30 is reserved for my "trainer" model).
The DX7 supports P-Link mode I believe, which is what I would recommend using. You will still need to use a default model in the DX8 - for me, again that's Model 30.

[Chris Bott - Moderator]

Hi Tim. How do you like the DX8 then? I'm getting the impression that it is all bad. Personally I think it's an excellent radio.

 

I certainly don't have to be two metres away to bind mine.

 

I think yr right on the flap alarm, although an alternative might have been not to let us select switches, in which case I'd rather have what we do have.

 

3 above seems to be a consequence of model match which I think is a great feature.

I also love the opportunity to save all 30 models to my PC just in case something goes wrong with the transmitter, or I loose it or whatever. I think you could save dozens of models and just put back any you like on any memory couldn't you? The only slight hassle is having to bind again.

 

Trainer modes - I can't see how this would be any different on any transmitter if all model memories are already used? It has always been an issue that it's the pupil's transmitter is usually the one bound to the model.

 

I think it's a very flexible system and as such will be used in many many ways. The beauty is that as perceived issues like these come up, the software can be even further improved to take them into account. It's such a leap forward from anything I've seen or used before that I'm not surprised that we're finding things that they haven't thought of yet.

 

 

[Tim Mackey]

Hi Chris....not meaning to give the impression that I dont like it at all - I very much do .

These "Issues" are in many cases just me finding my way around the set, and not faults or problems per se. I definitely had problems binding with some of the models ( bit of a pain having to do binding on all my 34 models ) and the US guys put me onto the 2 mtr distance thing...it definitely worked.

So, to clarify, I like the set - a big step up from my DX7 and DX6i, but just using this thread to share knowledge thats all.

[Capt Kremen]

My two penerth on the DX8 ...

On my second DX8 set since introduction last year, (first one replaced FOC by Horizon due to faulty/oscilating pots).

Second set returned for the recent factory recall software upgrade, also required both gimbals replacing as throttle channel faulty/oscillating!

Give them their due, I can't fault Horizon UK service for their free and very speedy turn around.

I, like the larger majority it appears, fly Mode 2 throttle and rudder on left hand stick.

Why therefore is the rudder dual rate switch on the top right of the set? Yes it can be assigned to the left 'F' Mode switch but can this be done as a permanent fixture and not require doing every time for a new model?

(The DX8 user manual doesn't help this user very much ... any ace out there able to write a good 'un?)

It's no big problem as I don't use rudder rates much, if at all.

When all my concentration is on the model though to remember, in the heat-of-the-moment, that rudder rate is on the right whilst the control itself is on the left!!!!

Overall a set with great potential but also a great many quirks too.

I'm still holding on to my Multiplex EVO Pro but I don't see many folk using these on 2.4 and the price of Spekky Rx's against the price of a MPX one...well ....

[Chris Bott - Moderator]

CK I have no idea if this is available here or even whether it is any good. But have a look at this Ultimate Guide

 

Tim I wonder if we can put something together here as we find "features" and work arounds?

I guess we already are.

I seem to be at a stage of life where I can get my head around complex stuff OK, but then can't always recall all the details at a later date.

Can you think of any way of compiling just the useful stuff in a format where we can find what we want again in the future?

 

 

[Capt Kremen]

Thanks for the link to the DX8 guide book Chris, will be interested to see if it's a useful addition to the knowledge base when it (hopefully) arrives in 10 days time from good 'ol US of A.

 

Like you, I can get the grey matter round the DX8 system OK but it's the detail for those functions/mixes etc. you set-up once for your latest model then don't use again for months/years(?)

 

A bit like the TV remote, the TV Hard Disc recorders, the digital camera, the microwave clock adjustment .... the ..... most electronic gadgets & devices with more sub-menus and gizzmos that you did the first time but now struggle to recall how did I set that up etc. etc?????

 

 

[Tim Mackey]

TBH, I am just making notes in a word doc as I go along - I'll have a think about how we may be able to get a combo of stuff on the forum here, but obviously only when we have sufficient stuff to include. As you say, this thread it self should be the birth of such a thing.

Another niggle I have is that there is absolutely no mention of which control surface servo plugs into which channel when setting up the various wing mix options.

And, what exactly is the difference ( connection wise ) between the flapperon and dual aileron mode

Be interested to see how the book is, as the manual is sure one piece of scant rubbish

[Pete B]

I ordered the 'Ultimate Guide' a few days ago, too - hopefully it will be written in such a way that my dull brain can take it in.....unlike the 'manuals'.

 

I'll let you know.....

Re the rudder D/R switch, it is in the same position on the DX6i and I can't recall that being raised as an issue. Not being a 3D flier (I wish....), I rarely have dual rates set on the elevator and rudder but I do set them on the ailerons and, just occasionally, elevator.

 

The likelihood is, if anyone wants to apply more throw to the surfaces, that they'll want to apply it to more than one surface at the same time, so it is easy enough to assign the rates to the same switch.

 

I keep my aileron and elevator rate switches on the relevant switches and, if I wanted rudder, I'd just assign it to the aileron switch.

Very difficult to put that in sensible English - must be the Merlot.........

Pete

[Chris Bott - Moderator]

Cool OK, the document is a good idea/start.

 

For which channel to plug in to I just refer to the monitor screen. They are labeled and change as funcions change. They always seem to be in the same channel order as the sockets on the Rx.

 

I can't think what the difference those modes could be, unless dual aileron mode just doesn't include using the ailerons as flaps??

 

I will be very interested to hear how the book is.

Having said that, the Tx is far more intuitive to use than most others that have similar functionality.

[Capt Kremen]

Agree Chris, the Tx is pretty intuitive but nevertheless, why should the end user have to discover how to use it and its quirks(?)

A simple step-by-step guide e.g. "To set-up a 4 channel aero with separate aileron servos, plug this servo into Rx socket #2" and so on ....

Possibly illustrated with some photos & clear diagrams so there's absolutely no ambiguity.

 

How many DX8 folk are using the telemetry features?

IF it was displayed on a type of Head-Up-Display (HUD) akin to that which full-size pilots view thru their cockpits, showing airspeed, azimuth etc. then, I think it could be safely used without taking your eye of the fast moving 'ball'/plane.

e.g. A screen attached to the aerial and thru which the modeller 'looks' to control his plane/heli whilst seeing the vital parameters of RPM, Temp, Batt Cell Volt, Capacity, urrent etc. displayed.

Could be tinted too for help against bright skies , whenever they infrequently occur in the UK!

Perhaps those familiar with screen display technology can comment whether this is now feasible, practical and cheap enough for model R/C to use.

As it is, unless set to audible warning alarms or vibration alert, I suggest Telemetry is of limited value and not very conducive to model flight safety.

 

[Chris Bott - Moderator]

I agree on the limited usefulness of telemetry CK.

 

My eyes will not focus close up so I cannot look down while flying anyway.

Alarms are useful and it is good to have a quick look through readings once landed though.

 

I have also acted as caller for a pilot who uses Jeti telemetry. He flies large electric planes and finds it extremely useful to have me calling out his flight pack mAh used readings regularly so he knows whether he has a reserve of power left or needs to think about landing.

 

It's a shame that Horizon don't seem to see the usefulness of a mAh reading.

[NigelH]

Posted by Chris Bott on 01/09/2011 14:06:37:

 

It's a shame that Horizon don't seem to see the usefulness of a mAh reading.

 

 

Hmmm. You don't actually know that

 

Someone asked Andy about that yesterday on RCG but he gave the usual 'cannot confirm or deny' line. They've got just about everything else though so who knows ?

 

I agree with Timbo about the channel allocations. While it's good to let the TX set up the wing and tail servo mixes, it wouldn't be a bad idea to then tell us what they are.

 

I really like the TM option but when you can monitor and alert on so many things, it may be wise to bleep for one thing, vibrate for another and do both for a third, just so that you don't need to look at the screen to see where the issue is.

 

[Chris Bott - Moderator]

No you're right we don't know that. I hadn't seen Andy say that. It sounds like an improvement on the dismissive replies some time ago to the same question.

Let's keep our fingers crossed.

[NigelH]

The other good thing he's created an 'Official AirWare' thread with a view to keeping out all that pain in the butt bickering between the stubborn 'PP' and some others. I unsubscribed from the DX8/DX10 thread a couple of days ago because I'm sick of all the useless noise.

 

[NigelH]

BTW, I think that Andy comment was in his new thread.

 

[Chris Bott - Moderator]

Thanks Nigel. I hadn't found that new thread. I have now

[Terry Walters]

Ok - another question re DX8 and this time it concerns the internal charger. I have the 2000mAh 4.8v NiMH battery. Try as I might within the limits recommended for charging using the charger plug included on purchase I cannot get it to a point where the visual display indicates a full charge - i.e. the battery display shows all black. I get a reading of 5.4v immediately after charging which drops to 5.1v very quickly. The drop in voltage I guess is a result of the charging having just finished and a 'false' reading given at that moment.

 

So what should I expect the residual 'full' charge to be and am I getting it with my 5.1v and therefore the visual battery display is not important?

 

The Tx works fine and settles down to about 4.9v.

 

How long do you other DX8 forumites leave your Tx on charge to get a 'full' battery?

 

Terry

[NigelH]

I'd been wondering about that one Terry. My pack tops out at about 5.5 volts.

 

Spektrum Andy recently said on RCG -

 

'How far down are you running the pack before charging it? You are safe when the batteries say 4.4V.

The DX8 charges at 200mA into NiMH cells. A fully-discharged pack will take 10 hours to charge, and should operate at least that long of actual operating time.

NiMH discharges very quickly initially, then holds at a lower voltage for a long time. You should see them drop to about 5V quickly, then take "forever" to get down to 4.4V.

The alarm goes off at 4.3V'

 

[Terry Walters]

Hi Nigel - thanks for that - I don't usually get below 4.9v so safe there then!

 

Maybe I should discharge down to 4.3v and then give a full 10hour charge to see if that gets me back up to 'full' or should I just accept it as it is using the "if it ain't broke don't fix it"?

 

Terry

[NigelH]

The manual's your friend but I seem to remember that they say give it something like that first time round. Have a look in the manual to confirm. Be aware that I don't think that you're supposed to leave it charging overnight though.

 

[Tim Mackey]

NiMHs dont like being left on slow charge for overly long periods.

Charging for the full 10 hours is fine if the pack is almost empty, otherwise its best to time it more conservatively.

I normally wait 'til mines down to around 4.5, then put it on the charger for about 4 -6 hours and then check unplug, and check the display. If its 5 or more, then Im off flying

Ill probably get the LiPo pack soon, at least then you know when its full, and the LSD is much better too.

[Terry Walters]

Nigel/Tim - all makes sense - will let mine drop lower than currently (no pun intended! .

Thanks for all the advice - will consider liPo later on. Do you have to make any 'electronic' changes to do so?

Terry