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HelicopterRadio - JR DMSS › 9303 ccpm and expo
10-25-2009 11:17 PM  8 years agoPost 1
UPSguy

rrApprentice

Toledo, OH USA

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In setting up the X9303 for ccpm there are 2 different menus you can apply expo. there is CCPM expo and the dual rate/expo menu. Is it redundant setting expo on both menus? If not, what is the difference?

Thanks in advance.

the man on top of the mountain didn't fall there

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10-25-2009 11:20 PM  8 years agoPost 2
Dood

rrProfessor

Wescanson

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No, it's not redundant. The "expo" in the Swash Mix menu isn't really expo at all.

By activating it, it will simplify setup by helping to eliminate swash interactions.

It's a nice feature.

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10-25-2009 11:32 PM  8 years agoPost 3
UPSguy

rrApprentice

Toledo, OH USA

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thank you

the man on top of the mountain didn't fall there

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10-26-2009 12:30 AM  8 years agoPost 4
dkshema

rrMaster

Cedar Rapids, IA

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Yes, the EXPO setting in the Swash Mix menu is there to attempt to address the non-linear output of a rotary servo arm. It's NOT the same thing as the EXPO you've come to know and love that's generally used to de-sensitize stick movements around neutral.

If you had already set up your pitch travel, then afterwards enabled that EXPO function, you'll find that it reduced the overall travel a bit. If you want to maintain the pitch numbers you originally dialed in, you'll want to re-check and readjust after turning on the EXPO feature from the swash mix menu.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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10-27-2009 10:04 PM  8 years agoPost 5
spike5150

rrNovice

Castle Rock, CO

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But it has problems...

If you have any subtrim on the cyclic channels, it is reported that enabling swash Expo will likely CAUSE interactions. This is common across the DX7, 9303 and even the 12X.

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10-27-2009 10:39 PM  8 years agoPost 6
RAK402

rrElite Veteran

Alhambra, CA

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"If you have any subtrim on the cyclic channels, it is reported that enabling swash Expo will likely CAUSE interactions. This is common across the DX7, 9303 and even the 12X."

This has been reported widely and probably does exist, however, the interactions removed by using Swash Expo have far more impact (positive impact) with regard to removing swash interactions than any which are introduced by the use of sub-trim.

Team KBDD/Compass Team Manger/Experience RC/Team JR Americas/WR Field Rep

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10-28-2009 02:39 AM  8 years agoPost 7
Pulento

rrVeteran

CHILE

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Does somebody use it ? And did it make a noticeable change ?

I also heard that rumor and since I have a click or two of subtrim I disabled it.

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10-28-2009 03:48 AM  8 years agoPost 8
RAK402

rrElite Veteran

Alhambra, CA

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I use Swash Expo in everything I fly that is CCPM.

Most people look for CCPM interactions in one way only (at least, that is the way it seems).

The level the servos at 50% collective, level the swashplate, the raise and lower the swashplate to its extremes to make sure it is level in all positions. If it is not level at the extremes, they adjust it with endpoint control in the radio until it is.

This is all well and good, but does not take into account the issue of differential throw, caused by the servo arms being in different positions in their rotation when the swashplate is tipped.

Without Swash Expo invoked, and after setting up as described above, move the swashplate fully to the right, then raise it and lower it. At full low collective, the servo on the right side of the ship will be at one extreme end of its throw. The one on the left will be closer to the center of its throw, and the elevator servo will be somewhere in between. All the servos will rotate the same amount for a given amount of collective movement, but the pushrods will all move a different amount, depending of how close or how far the arm is from 90 degrees. The servo whose arm is closest to being level will move the pushrod the most. The servo whose the arm is at the most extreme position will move the pushrod the least (it will move the pushrod sideways almost as much as it moves it in the direction that it will move the swashplate).

Raise and lower the swashplate while continuing to hold full right. Note that the swashplate tends to pitch slightly fore and aft as it is raised and lowered. This is due to the differential throw described above.

Now activate Swash Expo and perform the same experiment. The swash expo slows the rate of servo movement as the servos approach the center of their rotation, to some extent negating the influence of differential throw. The effect of Swash Expo seems to be most profound (IMHO) when doing axial rolls. It is easier to keep the straight and flat.

Team KBDD/Compass Team Manger/Experience RC/Team JR Americas/WR Field Rep

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HelicopterRadio - JR DMSS › 9303 ccpm and expo
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