[NSRCA-discussion] SD-10

James Oddino joddino at socal.rr.com
Mon Aug 24 21:14:11 AKDT 2009 

One fine point that might confuse this issue is the fact that 2048 is  
the maximum number of steps and that only comes when you move the  
stick and the trim and maybe the subtrim to the extremes in each  
direction.  In other words, moving just the stick from stop to stop  
will result in fewer steps even with the endpoints set to their  
maximum values.  So it is even more important to understand what Tony  
is saying if you want to maximize resolution.  Read it again.

Jim O


On Aug 24, 2009, at 9:55 PM, Anthony Frackowiak wrote:

> 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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