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Trex 250 with IKON2 mini - Too much pitch  

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gaz00
(@gazoo-grenon)
Active Member Customer
Joined: 3 months ago
Posts: 7
17/10/2020 9:53 pm  

Hey guys,

Trying to configure my TREX 250 but I am now in a pinch and was wondering what was the best way to continue. I made it thru tab 8 no problem until I hit the pitch value. I am trying to adjust the pitch to 11 or 12 degrees but the lowest I can get to is about 14ish degrees after which the tab 8 value goes into red at 20%. I understand that I need to reduce the travel mechanically but it is not possible due to physical constraint as the pitch link would bind on the servo.

Should I reduce my servo travel in my tx or adjust the pitch curve in my tx. Any idea would be appreciated.

 

Hopefully, it's clear.

 

Thanks

 

 

 


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BrainDev
(@customercare)
Member Admin
Joined: 2 years ago
Posts: 433
19/10/2020 9:07 am  

Is there a problem only with the collective pitch or also with the cyclic controls?
If the same problem exists for the collective pitch, it must also exist for the cyclic controls (Ailerons & Elevator).
Otherwise, it means that with collective pitch on the transmitter at zero the servo arms are not at 90° to the main shaft and the blades are not at zero pitch.
Could you send us the configuration file of your control unit?
Is it not possible to mount the uniballs on the servo horns in an inner hole closer to the centre of rotation? Can you send us a photo of swashplate servos?


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gaz00
(@gazoo-grenon)
Active Member Customer
Joined: 3 months ago
Posts: 7
19/10/2020 8:47 pm  

@customercare

Thanks for your quick reply.

To answer some of your questions:

SRV-1: Move the pitch stick to the middle position and use the + and – buttons to level the horn on servo SRV-1 to 90°  :   No problem to adjust (no red values)
SRV-2: Move the pitch stick to the middle position and use the + and – buttons to level the horn on servo SRV-2 to 90°  :   No problem to adjust (no red values)
SRV-3: Move the pitch stick to the middle position and use the + and – buttons to level the horn on servo SRV-3 to 90°  :   No problem to adjust (no red values)
If the correction values are too great (red values), move the horn position on servo spline and repeat. : No red values once done with this part

After all servo horns are at 90° (with the pitch stick in middle position), mechanically set the swashplate horizontally and head so the blade grips are at zero degrees pitch. (I had no issues levelling the swashplate with the 250 size Align swash leveler)

Pitch: Use the buttons + and - to increase or decrease max and min pitch (typically 12°). This is where I had to lower that number to 20% (red value) and still having pitch angle of 14 degrees positivley and negatively.

Red numeric values for Pitch and Cyclic: If the numeric values turn red during setup, the mechanical setup of the servos/Swashplates is wrong. Excessively high values should be solved by moving the uniball servo horns of the cyclic by one-hole outwards. Excessively low values should be resolved by moving the servo horns uniball of the cyclic servo horns by one-hole inward. This is where mechanically I had some limitations/constraints. Using the stock setup, I could not move the uniball one-hole inward as it would bind (physically touching) on the servo itself.

Update: After talking with a few friends, I was suggested to reverse the uniballs from the pitch link: the long uniball now being on the swashplate versus on the horn. This allowed me to move the horn uniball one hole inward. It fixed my problem but I am still at the lower limit of pitch setting on the ikon software. I was able to carry on with the ikon software without further problems.

What if I had no other options? Would there be an other way to reduce the pitch?

I attached a few pics to clearly show what I did. Config is also attached.

Stock versus mod
IMG 1216
IMG 1215
IMG 1217

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BrainDev
(@customercare)
Member Admin
Joined: 2 years ago
Posts: 433
20/10/2020 3:55 pm  

No!!!!
You can't absolutely stretch just two of the uniballs of the swashplate leaving the shorter back one.
This causes obvious interactions between cyclic movements and collective pitch.
All three uniballs of the Swashplate must be the same length.
Unless you are sure (because it is indicated in your model's manual) that the new length creates the geometry of a 135° or 140° plate.
In this case you need to select the correct swashplate (135° or 140° as indicated in the model manual) in the Brain2 software and then check that by giving all lift forward or all lift back the centre of the Swashplate does not change position / height

If short uniballs are still available / free in the kit, it is better to mount the uniballs on the outside of the servo horns than on the inside (link inclination is not a problem).

Or if you can't, then you'd better reduce the collective pitch curve in the transmitter.


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gaz00
(@gazoo-grenon)
Active Member Customer
Joined: 3 months ago
Posts: 7
21/10/2020 4:58 am  

@customercare

That makes sense, totally forgot that it would affect the overall geometry of the swashplate. Thanks. So I kept the shorter uniball on the horn and ordered a few more to reinstall on the swashplate and go from there.

More to follow... 


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