My First Trex now built but several questions....

[Gazzer1uk]

Hi all,

I've just finished building my first Trex 600 Nitro Pro model, last built a heli (TT Raptor 50) about 6 years ago so kind of relearning! I didn't think the manual is that good but did view most of the Finless Bob videos which I thought were very helpful if a little overly american in deliver!

I think I know the answer but.... I have a DSX9 transmitter and it seems a huge amount of pos and neg pitch, I am looking to limit this to plus 10 and minus 2 to relearn etc..... I think once fully set up mechanically, the best way to do this is reduce the ATV so that the transmitter limits the travel of the servos electronically and I can add or change the pitch electronically. Is that the case or is there a better other method?

Secondly the linkage between the tail and frame lever looks sloppy, I have built and checked it correctly all the supports are in the right place it just seems a little open to going wrong, or is this the way it is and it just works?

Finally (for now ) I have a JR 770 gyro (bought used from this site) and hideous amounts of movement on the tail, I assume again I should limit this travel (it smacks the boom in one orientaton) and that I can do this from the pot on the governor which the instructions seem to suggest....... and to make sure I have all the movemement I need to have the linkage dead set at 90 deg so 45 in either direction should be ample?? If there are any other ways of checking this, the manual is quite brief at this point I would be dead chuffed to hear!!!

many thanks,


Gaz

[moonmanflyer]

Hi Gaz
The trex manuals are some of the best out there, you have to see some others, mind you TT are very good too.
To set your pitches you are best to do it via the flight mode graphs and then you can set up 3 different flight modes, i.e. normal, idle up 1 and idle up 2, and you can switch in between them in flight.
yes the link is fine as it is, but you can stiffen it iffyou want by adding a carbon tube on the outside of the bar by removing one link and sliding over cutting to the right length and securing using ca glue, the sort of stuff that gets used in rc planes.
As for the gyro, yes you will have to set the limits via the gyro, but i am not very familiar with jr gyros so someone else might be able to help if they see this thread

[Lad]

Two JR 770’s live here……

You set the tail throw by adjusting the pot on the top of the gyro. You need to have the pitch slider central on the tail shaft before you start because the gyro only has one adjustment (whatever you set on one side is mirrored to the other).

Just make sure that you don’t bind in either direction after setting and you will be fine.

Cheers,

Lee.

[Lad]

Ps. To get the pitch slider central on the tail shaft, fold the tail blades over so they are at 90 deg to the tail blade grips (fold both blades towards each other).

When the tail blade tips align you have 0 deg pitch on the tail blades and the pitch slider should be central on the pitch slide shaft. I then adjust the JR 770 pot from this point until it just binds on one side, back it off slightly to avoid binding and you should then be okay the other side.

Lee.

[Gazzer1uk]

Thanks for that Lee,

Can I ask what gain you have set too please? And if you use exponential, it will be a good reference starting point for me!!!

Cheers,

Gaz

[Lad]

Gaz,

The JR770 needs high expo values, 40% gives a linear feel, 50% adds roughly 10% expo. I run mine at 50% rudder expo and they feel great.

For gain, I would suggest you start a something like 62% (this is what the manual suggests and it was spot on for me +/- 2%). I also suggest you set the tail servo up with a centre to ball arm length of 11mm.

Good luck!

Lee.

[Gazzer1uk]

Thanks Lee,

Works like a dream.........

BUT now I have noticed something else!!!

I have managed to set the main pitch +10 -2 but when I look at the elevator it appears to me I have it working backwards, i.e. pulling back on the stick lowers the front of the swash plate and raises the rear, which I think translates to less pitch on the front, more on the rear and the thing will move in the wrong direction......

I have a Dsx 9 tranny set up with 120 deg CCPM, 2 and 6 are aileron and 3 elevator...... pitch is fine up is up etc, and aileron appears good too left being dropped left side of swash when viewed from rear. I tried reversing 3 but it really screws everything up, something simples I am sure, any thoughts?

hmmmmm whilst writing this wonder what would happen if I physically change and reverse 2 and 6, and then 3.......

Gaz

[Gazzer1uk]

Yep if I reverse 2 adn 6 having swapped them over on the RX and then 3 the cyclic works OK on the swash yee haa....... except the pitch is now reversed

Something simples I am sure.. but can't see in the JR manual how to reverse the pitch

Bah humbug!

Gaz

[Vic.P]

Thanks Lee,

Works like a dream.........

BUT now I have noticed something else!!!

I have managed to set the main pitch +10 -2 but when I look at the elevator it appears to me I have it working backwards, i.e. pulling back on the stick lowers the front of the swash plate and raises the rear, which I think translates to less pitch on the front, more on the rear and the thing will move in the wrong direction......

I have a Dsx 9 tranny set up with 120 deg CCPM, 2 and 6 are aileron and 3 elevator...... pitch is fine up is up etc, and aileron appears good too left being dropped left side of swash when viewed from rear. I tried reversing 3 but it really screws everything up, something simples I am sure, any thoughts?

hmmmmm whilst writing this wonder what would happen if I physically change and reverse 2 and 6, and then 3.......

Gaz

Hi Gaz,
On the DSX 9 if the collective pitch is working correctly, ie up on stick is up on swash but the elevator is working in the wrong direction, go to the swash mix function, the aileron, elevator and pitch are set as + 60% by default change the elevator value to - 60% and it should work correctly.

[Vic.P]

Yep if I reverse 2 adn 6 having swapped them over on the RX and then 3 the cyclic works OK on the swash yee haa....... except the pitch is now reversed

Something simples I am sure.. but can't see in the JR manual how to reverse the pitch

Bah humbug!

Gaz

Having now swapped the channels to get aileron and elevator working correctly but swash moving in the wrong direction you should now change the pitch value to -60%

[GIXERMAN]

I thought align manual were better than most, i setup idle 2 first -zero mid stick full pitch range without binding mechanically, then enter what you like pitch wise on curve. then you can always get more on radio if required

[Gazzer1uk]

Thanks all for input......

Whilst watching TV I sat there and thought..... if the up stick position at 10deg is 82% and the -2 deg at the low position is 22% if I transpose the values, as mid stick is unaffected would it work........

Yes it did, but is that the right way to do this?? Should I reverse and swap the servos again and try the swash plate mix or leave as it is as technically, it is working as I now need and I can dial in the additional pitch as I get betterer!!!?

Thanks all for comments, good learning and challenges!

Gaz

[Vic.P]

Thanks all for input......

Whilst watching TV I sat there and thought..... if the up stick position at 10deg is 82% and the -2 deg at the low position is 22% if I transpose the values, as mid stick is unaffected would it work........

Yes it did, but is that the right way to do this?? Should I reverse and swap the servos again and try the swash plate mix or leave as it is as technically, it is working as I now need and I can dial in the additional pitch as I get betterer!!!?

Thanks all for comments, good learning and challenges!

Gaz

If you put everything back as it was at the start of this thread and then use the swash mix and alter the elevator value to - 60% then it should all work correctly.
You really do need to get all controls working in the right sense first off and with the swash plate exactly level and then you can set the pitch curves by starting with idle 1 and getting mid stick properly zeroed.
When you set up pitch for zero mid stick in idle 1, look at the in and out values (bottom left in pitch curve screen) which should both read 50 which means the stick is positioned exactly at mid stick. Then without touching the stick again you can adjust the value for point 3 until the pitch guage reads zero. Now you will have the collective pitch range exactly centred so that positive and negative pitch values will cover the correct range for each.
Then set up the curves for idle 1, idle 2, HOLD and normal to the recommended values and you should be good to go.

[Gazzer1uk]

Thanks Vic,

I think your approach is more ordered and best for the future, it should not take that long now as I am more competent in understanding what is going on by process of brain power and assimilation...... I also realised why I had not been through this loop before and of course my TT Raptor was not a CCPM machine.

Half an hour tonight and I should be good to go.....

I have a silly question though, is there an explicit idle up switch on the DSX9? Or is this achieved through the flight mode switch a 3 position switch on the right hand side?

I always think the stupidest question is the one not asked although the above may rate closely!!!

Cheers,


Gaz

[Lad]

Gaz,

It's the 3 way flight mode switch.

I assume you will use position 1 as 'Normal'. If you can't disable positions 2 and 3 in the DX9 (not sure ~ I don't have one) remember to set the settings the same as the Normal position in case you accidently hit the switch whilst in flight.......

Lee.