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Old Jan 09, 2003, 02:42 PM
Mike Shellim
Guest
n/a Posts
[RCSE] How to implement Reverse Diff

Hi folks,

I'm researching an article about Crow setup and Reverse Diff.

Is it correct that Multiplex are the only manufacturer to allow reverse diff
to be programmed? How do you implement this on other radios? I remember
there was no solution on my old FF7, and I believe the same applies to the
U8 or 9C. Is it possible on other mid range Jap radios?

Just to recap: the problem is well known to F3X flyers: you have a two or
four-servo wing on a model like the Ellipse 2V. You set up differential on
the ailerons. You also set up crow brakes, i.e. flaps down, both ailerons
up, operated by the throttle stick.

The problem occurs at full brake. At this stage both ailerons are deflected
up at or near their maximum. If you now now apply an aileron signal, one
aileron wants to go up even further (ouch!), the other only wants to go down
only 50% or so (because of diff). This does not provide satisfactory roll
control! To achieve full roll control with brakes on, you want NO upward
movement on the upward aileron, and FULL downward movement on the other.
i.e. *reverse* differential.

This is addressed neatly on all MPX radios (including the Cockpit MM) using
Aileron Diff Suppression and Servo Limit. The aileron diff suppression
provides full movement for the downgoing aileron. It works by progressively
suppressing diff, as the brakes are applied. Servo Limit prevents the
upgoing aileron from moving any further.

How is this done on non-MPX radios?

Thanx
- Mike


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Old Jan 09, 2003, 03:12 PM
Brett Jaffee
Guest
n/a Posts
Re: [RCSE] How to implement Reverse Diff

Mike Shellim wrote:
>
> Hi folks,
>
> I'm researching an article about Crow setup and Reverse Diff.
>
> Is it correct that Multiplex are the only manufacturer to allow reverse diff
> to be programmed? How do you implement this on other radios? I remember
> there was no solution on my old FF7, and I believe the same applies to the
> U8 or 9C. Is it possible on other mid range Jap radios?


On the 8U and 9C, I think it might be possible to set up a couple of PMIX's that mix the aileron channels to themselves to give increased throw in the direction desired (essentially overriding the programmed in differential). The problem is that it would not be proportional to the amount of CROW being used, you'd only be able to turn it on or off. However, it might be possible to have the on/off switch be the throttle stick, so that the reverse differential didn't come into effect until, say, 50% of crow was deployed.

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Old Jan 09, 2003, 04:32 PM
Jon Stone
Guest
n/a Posts
Re: [RCSE] How to implement Reverse Diff


>Is it correct that Multiplex are the only manufacturer to allow reverse diff
>to be programmed?


No. The Airtronics Vision and Stylus have pre-programmed support for
reverse differential in all flight modes from day 1. You simply program
the differential % to a negative value for reverse differential. Both
the Stylus and Vision have a separate aileron differential percent for each
of the various flight modes (launch, speed, thermal, land).

Both of these radios have been on the market for a long time. The Vision
for 10+ years, I believe.

Jon Stone


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Old Jan 09, 2003, 05:32 PM
John Derstine
Guest
n/a Posts
RE: [RCSE] How to implement Reverse Diff

JR has same
JD

-----Original Message-----
From: Jon Stone [mailto:thermals@earthlink.net]
Sent: Thursday, January 09, 2003 5:28 PM
To: Mike Shellim; Soaring@airage.com
Subject: Re: [RCSE] How to implement Reverse Diff



>Is it correct that Multiplex are the only manufacturer to allow reverse

diff
>to be programmed?


No. The Airtronics Vision and Stylus have pre-programmed support for
reverse differential in all flight modes from day 1. You simply program
the differential % to a negative value for reverse differential. Both
the Stylus and Vision have a separate aileron differential percent for each
of the various flight modes (launch, speed, thermal, land).

Both of these radios have been on the market for a long time. The Vision
for 10+ years, I believe.

Jon Stone


RCSE-List facilities provided by Model Airplane News. Send "subscribe" and
"unsubscribe" requests to soaring-request@airage.com. Please note that
subscribe and unsubscribe messages must be sent in text only format with
MIME turned off.

RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to soaring-request@airage.com. Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
Old Jan 09, 2003, 11:43 PM
Chris Kaiser
Guest
n/a Posts
RE: [RCSE] How to implement Reverse Diff

The mid-range Futaba radios sort of have this capability: the aileron
differential setting actually affects the throw relative to the output
channel neutral points, not the aileron input itself. Basically, when
the ailerons are raised above their neutral position (as in crow)
you have equal throw in both directions. When an aileron passes thru
it's neutral point the differential setting takes effect on that
aileron only. Bit hard to explain but I've found it to work pretty
well - I flew an E2V for years on an 8UAP and it had plenty of roll
authority under crow.

The 9ZAP can do reverse differential with no problem. There is a
"volume" setting under the aileron differential menu that allows
you to have the amount of differential vary with the throttle stick
position (or any input control for that matter).

Ciao - Chris

******
Chris Kaiser
Auckland, NEW ZEALAND

> -----Original Message-----
> From: Mike Shellim [mailto:mike@rc-soar.com]
> Sent: Friday, 10 January 2003 9:35 a.m.
> To: Soaring@airage.com
> Subject: [RCSE] How to implement Reverse Diff
>
>
> Hi folks,
>
> I'm researching an article about Crow setup and Reverse Diff.
>
> Is it correct that Multiplex are the only manufacturer to allow
> reverse diff
> to be programmed? How do you implement this on other radios? I remember
> there was no solution on my old FF7, and I believe the same applies to the
> U8 or 9C. Is it possible on other mid range Jap radios?
>
> Just to recap: the problem is well known to F3X flyers: you have a two or
> four-servo wing on a model like the Ellipse 2V. You set up differential on
> the ailerons. You also set up crow brakes, i.e. flaps down, both ailerons
> up, operated by the throttle stick.
>
> The problem occurs at full brake. At this stage both ailerons are
> deflected
> up at or near their maximum. If you now now apply an aileron signal, one
> aileron wants to go up even further (ouch!), the other only wants
> to go down
> only 50% or so (because of diff). This does not provide satisfactory roll
> control! To achieve full roll control with brakes on, you want NO upward
> movement on the upward aileron, and FULL downward movement on the other.
> i.e. *reverse* differential.
>
> This is addressed neatly on all MPX radios (including the Cockpit
> MM) using
> Aileron Diff Suppression and Servo Limit. The aileron diff suppression
> provides full movement for the downgoing aileron. It works by
> progressively
> suppressing diff, as the brakes are applied. Servo Limit prevents the
> upgoing aileron from moving any further.
>
> How is this done on non-MPX radios?
>
> Thanx
> - Mike
>
>
> RCSE-List facilities provided by Model Airplane News. Send
> "subscribe" and "unsubscribe" requests to
> soaring-request@airage.com. Please note that subscribe and
> unsubscribe messages must be sent in text only format with MIME
> turned off.


RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to soaring-request@airage.com. Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
 


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