Boo2

Hi,

I found the following quote in another forum under the title "BEWARE! Futaba 9C Tx - Mix offsets changing in flight" but I believe it is more appropriate for me to post my question here :


My question is : has this problem been fixed in the new 9C Super ? My reason for asking is that I am considering upgrading from a FF8 and this problem would be a show stopper for me.


Many thanks,

Boo

bigman

I did have the bad experience with myMini Blade. As I remembered that I had set the crow for Mini Blade of down elevator for 16%. It is a good value for Mini Blade. I had experienced to land MB at this value with smooth landing. After several flights, I had put aside of MB for nearly two months. After two months I flied MB again, I had not checked the setting of crow. When I landed MB, it dived sharply and made a outside loop and hit the grassland. I immediately checked the crow setting and down elevator was set to 50%.
After that incident, I usually checked the crow setting of each plane and sometimes found the setting for down elevator had been changed to a greater value. It was very surprised that the value always be increased but not decreased!
Please remind all the 9C users to check the crow setting before each flight especially the down elevator value.

bigman

Please be informed mine is 9CAP not 9CAP Super

marcellus

Bax and Krista will be after us for 'discussion' on their forum!

I think what's described above is a positive feature of the 9C, not an issue or problem.

You get independant primary control trim settings (elevator/rudder/aileron) for each of the crow/flap and reflex programmes. There is no way that elevator compensation on crow, for example, could be the same setting as elevator trim for normal flight. Switch the crow off for normal flight as you do for flap and reflex and there is no problem. The crow trim setting won't change unless crow is switched on when the trim lever is moved.

I agree, the manual should more clearly explain that the trim settings are independant for each of the crow/flap/reflex programmes.

Boo2

Hi,

I am not particularly concerned about whether it is a bug or feature, of course this will depend upon the perception of the individual user.

I just need to know whether the 9C Super behaves in the same way as the 9C in this respect, so I can make a purchasing decision. Sorry to be unclear in my original post.

Thanks,

Boo

Bax

My Feedback: (11)

This is not a "bug". What happens is that when you have a mix on, depending upon the mix, the trim on the primary will affect downstream mixes. It's not changing the "offset", but trimming. If you have rudder mixed to aileron, then adding aileron trim will affect rudder. If you use the pmixes, you can select in some of them whether the trim will affect the mixed-in channel. In some of the pre-made mixes, this feature may be on or off.

This isn't changed in the Super version.

We're sorry for the delay in response. This wound up on the second page and got lost for a bit.

Boo2

Well, I bought a 9C Super and I don't agree with your assessment that this behaviour is not a bug. (In the glider modes the behaviour has been fixed in the 9C S).

In Acro mode if you set the airbrake so it is activated by the throttle stick a near the low throttle position you still get the behaviour :

1. Set airbrakes to be operated the throttle stick moving below (say) 25% and conditioned by a switch.

2. Leave programming mode and switch the airbrake off with the switch.

3. Trim the model, (say) aileron trim.

4. Activate the switch but keep throttle above 25% so the airbrake is not activated.

5. Trim model aileron some more.

6. Oops ! No effect ! I tried moving the trim all the way and nothing happened ! That's weird, I'd better land and investigate...

7. ... See what's coming ?...

8. Reduce throttle below 25% to land....

9. Oh, now I know where all that aileron trim went !

10. Walk to field carrying a bin bag.


This is so well known and so well documented that I'm surprised Futaba hasn't issued a product recall. What happens when someone discovers this defect when they're flying a 1/3rd scale Boeing 707 at an air display ? The product liability issues must be tremendous...

So what are Futaba going to do to fix it ?



Boo

Bax

My Feedback: (11)

Again, this is not a "bug" or a "problem". When the mix is on, the trims will work on the offset. The instructions included in the 9C system mention that the trim lever adjusts the control's setting in the mix when it's turned on. It does not act as a regular trim unless you turn off the mix.

Boo2

You have ignored what I said. The bug is that the trims work on the offset when the mix is off. In my example above, the mix is activated by the stick being moved below 25% as well as a switch being set. The trims adjust the offset whenever the switch is set alone, which ought not to be enough to activate the mix. I would like to forestall you from saying that the mix is activated solely by the switch since that is an exact statement of the bug : the mix (and hence trim-offset) should only be activated by the switch AND stick position together because that is when the mix becomes effective and the control surfaces start to move.

The flying example I gave proves that the behaviour is defective and I do not understand why Futaba is in such vehement denial over this ? I have heard of several models that have been destroyed by this defect and it is only a matter of time before someone is injured as a result.

I am talking about the 9C S and the behaviour has been fixed in this TX for the Glider modes where the trim can be selected to control either the offset or the trim. The fact that Futaba have fixed it in the glider model template shows that they tacitly acknowledge it to be a defect.

In the Acro model template it is unaccountably not fixed and the problem therefore remains. Of course the product liability issues with a large scale powered model are hugely greater than those with a glider and I surmise that this is the reason for Futaba's defensive posture on this issue.

To sum up, anyone who reads and understands the flight scenario I gave will be forced to agree that the behavioour is defective and I call on Futaba to issue a general global recall of this TX to modify the programming and to prevent an accident where somebody may be killed or seriously injured.


Boo