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05-28-2013 12:33 PM  5 years agoPost 1
myjane

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new zealand

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in expo settings at the bottom is DR , by lowering DR down to say 40% will that slow the piro speed down if so will it upset the gyro gp780 i am trying to slow the piro down for smooth sport flight thanks

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05-28-2013 01:19 PM  5 years agoPost 2
dkshema

rrMaster

Cedar Rapids, IA

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The endpoint setting (travel amount) for the rudder channel controls the maximum yaw rate ("piro" rate) the gyro will allow the heli to have.

Normally, you'll set the system up with the rudder endpoints set to 100%, then will adjust the left and right rudder endpoints to achieve equal left and right yaw rates.

If you wish to increase the rate, increase the rudder travel endpoint value. To decrease the rate, decrease the rudder travel endpoint value.

Changing the dual-rate value, in and of itself, will do no good, unless you also flip the switch assigned to the dual-rate setting. Your transmitter probably defaults to having the rudder dual-rate switch make the selection. If you don't flip that switch once you've set up a different endpoint setting, you won't be using the different set of endpoints.

It will NOT upset the gyro. Changing the neutral point by using TRIM after it has been initialized WILL, but changing the endpoint/travel setting will not.

-----
Dave

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

Team Heliproz

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05-28-2013 01:33 PM  5 years agoPost 3
myjane

rrApprentice

new zealand

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dx7
hi thanks will the travel adjust slow the piro or just limit the degrese of pitch thanks

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05-28-2013 02:18 PM  5 years agoPost 4
Richardmid1

rrProfessor

Leeds, England

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Actually changing the D/R's does affect piro rate. The GP780 will piro pretty much exactly the same rate either way so no need to adjust left and right individually. Just remember to change the D/R in throttle hold AND normal flight mode, the amount of times ive landed (using throttle hold for a mini auto) to adjust piro rate and not adjusted it for normal flight mode then took off and nothing had changed!

I can't remember the last time I used servo travel adjust for anything other than setting up a throttle servo or one of the aux or gear channels to adjust a governor or gyro gain!

60% of the time, it works every time!

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05-28-2013 03:40 PM  5 years agoPost 5
dkshema

rrMaster

Cedar Rapids, IA

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or just limit the degrese of pitch thanks
No, do not do that. You want the servo to be able to make the pitch slider travel from stop to stop (without stalling the servo, of course). The gyro/servo must be able to use the entire pitch range available to do their job correctly.

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When flying a heading hold gyro, you no longer actually control the servo hooked to the tail rotor pitch mechanism. The gyro does. It figures out where the pitch slider needs to be in order to maintain the desired flight characteristic.

Your rudder inputs simply tell the gyro which direction to let the servo move, and how fast the tail should move in order to get to the commanded position.

The maximum rate at which the gyro will allow the heli to spin is set by the travel adjust (endpoints) of the rudder channel. Adjusting the rudder travel endpoint settings in the transmitter sets the maximum rate you'll allow the gyro to let the heli spin. It does NOT adjust the amount of throw the servo/pitch slider sees.

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As I noted in my first post, just because you have SET the rudder Dual Rate value to something other than the default 100%, doesn't mean you're USING that secondary value.

Setting a dual-rate value does nothing till you actually choose to use that value by flipping the rudder dual rate switch. It doesn't happen by magic, it takes a conscious decision and a planned action to make it work.

The ONLY time the secondary value set in the Rudder Dual Rate menu is in use, is when you have told the transmitter to USE that other value, and that ONLY happens if you flip the Rudder Dual Rate switch to its other position.

Depending upon your transmitter, you may be able to slave the rudder dual rate switching function to something other than the rudder dual rate switch (flight mode, maybe). But unless you actually set up and engage that programming feature, the secondary value will go unused.

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The Rudder dual rate switch has two settings, quite often referred to as "0" and "1" (a simple binary digit thing going on here). If the rudder dual rate setting for position "0" is 100%, and if the rudder dual rate setting for position "1" is 50%, as long as the rudder dual rate switch stays in position "0", the TX will use 100% rudder travel limits. ONLY if you move the rudder dual rate switch to position "1" will you then use the alternate 50% setting.

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If your heli spins too fast, you have two options --

1. You have the pushrod mounted too far out from center on the rudder servo, therefore your mechanical gain is too high and your electronic gain is too low (as well as limiting the amount of available servo travel and resolution). In this situation, the gyro is barely in control of the tail, and when it is, it has limited ability to do anything.

2. Your rudder endpoint settings need to be decreased and you actually need to be using those endpoint settings.

To correct problem number 1, with your rudder endpoints set to 100% and the gyro limits at their default setting, you should mount the ball on the servo arm at a distance where your servo can move AT LEAST +/- 45 degrees from neutral without slamming the pitch slider into either the left or right limit of mechanical travel. Mount the ball as close as you can at this point, then use the rudder travel limit setting feature to insure the pitch slider moves end to end without stalling the servo as it tries to move.

To correct problem number 2, assuming you have corrected problem 1, change the rudder travel endpoint settings to achieve the yaw rate that you are looking for.

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EDIT -- Just re-read your last post. The rudder endpoint settings (aka travel adjust, and Dual Rate if you have it set up and properly enabled) changes the maximum rate at which the gyro will let the heli spin. You maintain the ability for the servo to travel stop to stop on the pitch slider, but the gyro is what determines rate. It does that by controlling the tail rotor pitch as you're flying.

-----
Dave

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

Team Heliproz

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05-29-2013 06:32 AM  5 years agoPost 6
myjane

rrApprentice

new zealand

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dx7
dkshema thanks so i am confused , i was trying to slow down the piro speed for sport flying , not 3d every body said ,,,expo so dialed in 40% ,still to fast , playing around with the dx7 i came accross dr on the bottom of the screen dialed it down to about 40 and the tail was very slow and smooth was this the wrong thing the push rod is 12 mm off ctr of the servo , i was copying the settings off my rappy 30 for the tail as it flys beaut would travel adjust be the place to go or would it limit the distance the tail blades will travel and confuse the gyro ,

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05-29-2013 06:42 AM  5 years agoPost 7
dkshema

rrMaster

Cedar Rapids, IA

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Expo doesn't change overall channel travel. The endpoints stay the same. All expo does is modify how the channel outputs respond to the stick around neutral. It can make the channel less sensitive to movement around neutral, or it can make it more sensitive. But in the end, travel remains unchanged. Maximum allowable yaw rate remains unchanged.

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Dual rate, on the other hand, when it is enabled, DOES change the overall travel amount, and does NOT affect how the channel behaves around neutral. Channel output remains linear, only the endpoints (travel) change. It appears you enabled it.

As long as you have dual rate enabled, and the values are less than the "non" dual rate settings, you are effectively reducing the rudder travel settings, and thereby slowing down the maximum allowable yaw rate.

No confusion, the gyro behaves as it should, you have a more controllable heli as a result.

-----
Dave

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

Team Heliproz

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05-29-2013 12:49 PM  5 years agoPost 8
Richardmid1

rrProfessor

Leeds, England

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You do not have to enable d/r's on a dx7. As the rudder dr switch is also the throttle hold switch therefore with throttle hold on you are also using the secondary rudder dr which is why I said in my first reply to make sure you change the dr in and out of throttle hold.

This is exactly what d/r's were intended for.

60% of the time, it works every time!

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05-29-2013 02:45 PM  5 years agoPost 9
dkshema

rrMaster

Cedar Rapids, IA

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Different ways of solving the same problem. It's fortunate that in the older DX7 (and DX7 SE), that the Throttle Hold switch happens to be defaulted to operate from the Rudder D/R switch.

You do state that if you intend to go the route you suggested, to match the Dual Rate settings for both positions of the Rudder Dual Rate switch, so that you end up with the same value of D/R in both positions of the TH switch.

You do realize that leaving the RUDD D/R at 100%, and changing the rudder endpoints to 50% achieves the same result as leaving the endpoints at 100% and changing the RUDD D/R settings to 50%, I hope.

-----
Dave

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

Team Heliproz

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05-29-2013 03:11 PM  5 years agoPost 10
Richardmid1

rrProfessor

Leeds, England

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You do realize that leaving the RUDD D/R at 100%, and changing the rudder endpoints to 50% achieves the same result as leaving the endpoints at 100% and changing the RUDD D/R settings to 50%, I hope.
Yes I just find it easier to change the one value and its in the same screen as EXPO and you can change the rates for aileron and elevator while your at it (beastx).

60% of the time, it works every time!

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05-29-2013 04:25 PM  5 years agoPost 11
dkshema

rrMaster

Cedar Rapids, IA

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I never bother with dual rates, I have them all set to the same value. It prevents surprises if a dual rate switch is accidentally switched.

So we ARE on the same page, we only attack the problem in a different manner.

Not all radios use the Rudder dual-rate switch as the default for controlling throttle hold. The moral here is to know what your radio default settings are, and use that info accordingly. Meanwhile the OP is happy.

-----
Dave

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

Team Heliproz

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