[NSRCA-discussion] SD-10

Mon Aug 24 20:55:32 AKDT 2009

I'll try to explain this as I understand it. With a 2048 system you  
get 2048 TX step outputs through the entire stick travel only if the  
electronic throws in the TX are set to Max. Say that's 150% Travel at  
100% Dual Rate. Those numbers vary amongst the brands and models but  
this is a start. Any reduction from there will reduce the 2048 by some  
percentage. Let's say Travel is set to 100% and Dual Rate remains  
100%. You have just reduced the number of steps by 33% so now you're  
down to around 1350. If you reduce the Dual Rate to 80% from there  
you're now flying on 1080. If this started out as a 1024 you would end  
up at 540. I guarantee you'll feel the difference between 1080 and 540.

I always try to maximize the electronic throws and set the mechanicals  
to get the surface travel I desire. But some things are inevitable. To  
get the model to properly break in a spin takes a lot of elevator  
deflection, so I end up flying with DR set to 50% or so for normal  
flying. The higher 2048 system makes a difference with this sort of an  
example. And I do believe the better servos will respond to this fine  
of a command.

Hope this isn't too confusing.

TonyF

On Aug 24, 2009, at 8:14 PM, Atwood, Mark wrote:

> The resolution is for the full throw of the servo. If you bump your  
> endpoints up to 150% and have 135deg of travel, you have 512 / 1024  
> or 2048 individual points in between.  At a normal 100% that's  
> across 90degs of throw.  If you dial your endpoints down, it's  
> spread across a smaller arc.
>
> We're talking about extremely fine movement even at 512 resolution.
>
> What's nice is that all the components of the Accuracy "system" are  
> improving together.  The pots in the new radios (all brands) are  
> significantly more accurate, the digital servos of all brands are  
> significantly more accurate, and our linkage systems continue to  
> improve as well.  My argument was simply that after 1024 (and  
> probably lower actually), the resolution is probably not the "weak  
> link" in the accuracy chain.  We have too much slop elsewhere.  Even  
> a tight servo has some lash, as do the connections to the servo and  
> even movement of the control surface on the hingeline.
>
> Admittedly though, On a LARGE control surface like a 40% IMAC  
> Rudder, you can still see the surface "Step" if you move it slowly  
> and watch carefully even with 1024.  So to say that 2048 is not  
> smoother would be foolish.  But on our pattern planes and the throws  
> we use, the other sources of error take resolution off the critical  
> path to more accuracy.
>
> So to slightly change the topic, how do we get spec's on the  
> resolution/accuracy of the servos?  Does anyone publish that? (I'm  
> pretty sure Atx doesn't).  That would be as important than just  
> about any other spec I would think.
>
> -----Original Message-----
> From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org 
> ] On Behalf Of Lisa n Larry
> Sent: Monday, August 24, 2009 10:31 PM
> To: 'General pattern discussion'
> Subject: Re: [NSRCA-discussion] SD-10
>
> I'm curious...
>
> How many degree of servo throw for 1024/2048 are we talking?
>
> -----Original Message-----
> From: nsrca-discussion-bounces at lists.nsrca.org
> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of  
> Ronald Van
> Putte
> Sent: Monday, August 24, 2009 8:34 PM
> To: General pattern discussion
> Subject: Re: [NSRCA-discussion] SD-10
>
> Geez!  I was happy with 512.
>
> Ron VP
>
> On Aug 24, 2009, at 3:13 PM, mike mueller wrote:
>
>> So a 2048 is smoother than a 1024 by double. I wonder at what
>> point you no longet "feel the difference".?
>> For me it could be as soon as tomorrow. M2
>>
>> --- On Mon, 8/24/09, Jay Marshall <lightfoot at sc.rr.com> wrote:
>>
>>> From: Jay Marshall <lightfoot at sc.rr.com>
>>> Subject: Re: [NSRCA-discussion] SD-10
>>> To: "'General pattern discussion'" <nsrca- 
>>> discussion at lists.nsrca.org>
>>> Date: Monday, August 24, 2009, 3:05 PM
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> Frank, you
>>> are getting your terms mixed
>>> up. The 1024 & 2048 refer to the number of
>>> "steps" from one end
>>> of the stick movement to the other. The speed, known as
>>> latency, is the time it
>>> takes from the instant you change the stick to the time the
>>> servo moves. Actually,
>>> it is the time until the servo receives the command to
>>> move. The two functions
>>> are not dependant upon each other.
>>>
>>>
>>>
>>> As far as
>>> keeping up, that depends on
>>> servo speed. It is possible to have a switch change which
>>> instantly commands a
>>> function from low to high, for example. The time to get
>>> there, however, will
>>> depend on how fast the servo can move.
>>>
>>>
>>>
>>>
>>>
>>> Jay Marshall
>>>
>>>
>>>
>>> -----Original
>>> Message-----
>>>
>>> From:
>>> nsrca-discussion-bounces at lists.nsrca.org
>>> [mailto:nsrca-discussion-bounces at lists.nsrca.org]
>>> On Behalf Of
>>> frank
>>>
>>> Sent: Monday,
>>> August 24,
>>> 2009
>>> 3:30
>>> PM
>>>
>>> To:
>>> 'General pattern
>>> discussion'
>>>
>>> Subject:
>>> [NSRCA-discussion] SD-10
>>>
>>>
>>>
>>> Hi Anthony,
>>> Jim, Mark , and Others
>>> who Responded,
>>>
>>>
>>>
>>> Thanks for
>>> your valuable input.
>>> I've read that this radio's resolution is or is
>>> among the very
>>> fastest; so much so that even digital servos
>>> can't keep up with it.
>>> I understand  that the system is 1024 , but
>>> can't help but
>>> wonder why it isn't 2048. I'm sure
>>> I'll get past my
>>> hangup, but would appreciate everyone's
>>> insight's on that
>>> one.
>>>
>>>
>>>
>>> Thanks,
>>>
>>> Frank
>>> Imbriaco
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> -----Inline Attachment Follows-----
>>>
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>>
>>
>>
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