[NSRCA-discussion] Aileron servo arm size and resolution?

Thu Jan 4 09:07:59 AKST 2007

effects of controls on a snap (basic)

Elevator kicks the nose up to increase AOA initiating stall
Rudder kicks the tail to the side to force one wing to stall faster/more 
completely than the other, initiating rotation.

according to th way the Pattern scoring rules are written, the controls have 
to be applied in the correct order.  Kicking rudder, then elevator will give 
a snap-roll, but not one that is acceptable for competition.  Some planes 
can snap roll just by applying full rudder.... (Piper Cub for example)

Aileron applied in the direction of the rotation will "tighten" the snap, 
having the tail of the plane go through a smaller arc radius.  applied 
opposed to the snap will "flatten" the snap presenting more of the belly of 
the plane to the direction of flight (increasing G load and causing the 
plane to slow significantly)

A snap roll can be related to a spin in the way the plane responds to the 
controls, and the snap looks much like a spin (if you've ever seen a REAL 
spin rather than a spiral)  Note that a "flat spin as done by a 3D plane is 
accomplished by applying opposed aileron to present the belly of the plane 
to the direction of flight.

Excess opposed aileron can cause the plane to "snap out of the spin" (a 
really strange sounding thing.... to stall out of a stall ???? ) into a dive 
when trying for a flat spin. (with power on and our very high 
power:weight... it doesn't work as a reliable spin recovery technique for 
full scale which won't have 2:1 power:weight)

FHH
----- Original Message ----- 
From: "Kelly Regan" <kelly.regan2 at verizon.net>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Thursday, January 04, 2007 8:14 AM
Subject: Re: [NSRCA-discussion] Aileron servo arm size and resolution?

> Ken,
> I like to set up up my planes so I do not have to use a duel rate
> switch if possible.  When I do set up rate switches I use them as
> conditions and place all surfaces rates on one switch.
>
> On the Brio I have more rate left on the elevator and rudder then I
> did on the aileron.  I think I am around 90% on low rate with the
> ATV at 130.
>
> I have not fine tuned the amount of throw I need for snaps since...
>
> 1) I don't know what a good snap looks like
> 2) I don't understand the affects that each surface has on the snap.
> 3) I will only need to fly sportsman for now
>
> I hope that some time in the spring or summer I can get don to do a few
> more trim flights and test out the snaps to see if I have enogh throw
> on the surfaces.
>
> It is hard to adjust your plane when you don't know what you are looking
> at!  ;)
>
>
> Ken Velez wrote:
>>   I have one other question for Kelly. If you set up your servos
>> mechanically to full resolution and the output travel in your control
>> surface is 10 deg. "in this case ailerons" I'm assuming your elevator is 
>> in
>> the same vicinity  How do you get enough throw for snaps stalls or spins?
>> Just wondering.
>>
>> Ken
>> ----- Original Message ----- 
>> From: "Dave Lockhart" <davel322 at comcast.net>
>> To: "'NSRCA Mailing List'" <nsrca-discussion at lists.nsrca.org>
>> Sent: Wednesday, January 03, 2007 11:37 PM
>> Subject: Re: [NSRCA-discussion] Aileron servo arm size and resolution?
>>
>>
>>
>>> Kelly,
>>>
>>> Without going into default and max/min values for each parameter for 
>>> each
>>> brand radio, endpoints, ATV, AFR, dual rates, mixers (built in, or 
>>> Pmixes,
>>> or differential mixes), and trim all have an effect on the amount of 
>>> servo
>>> travel.  You will have max servo resolution when the servo moves through
>>> the
>>> full range of available travel (typically 90 degrees, 45 degrees each
>>> direction).
>>>
>>> The setup is a compromise between "speed" and resolution.  Move the
>>> linkage
>>> out on the servo and reset the servo throw to yield the same control
>>> surface
>>> deflection, and the resolution has gone down and the time needed for the
>>> control surface to reach max deflection has also gone down.
>>>
>>> So, if your flying rates have 45 degrees of servo rotation in each
>>> direction, you are at max resolution.  In practice, if your servos are
>>> moving 30-35 degrees in each direction, you will be in pretty good 
>>> shape,
>>> and you have some servo throw "leftover" to accommodate trim, sub trims,
>>> and
>>> mixers.
>>>
>>> Dave
>>>
>>> -----Original Message-----
>>> From: nsrca-discussion-bounces at lists.nsrca.org
>>> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Kelly 
>>> Regan
>>> Sent: Wednesday, January 03, 2007 10:27 PM
>>> To: NSRCA Mailing List
>>> Subject: Re: [NSRCA-discussion] Aileron servo arm size and resolution?
>>>
>>> I forgot to add that I am running 6.0 volts with a
>>> 7.2 volt li-ion pack and Fromco regulator.
>>>
>>> Fred, can you explain or give me an example of what you
>>> mean by bad control system?
>>>
>>> I have been trying to understand the affects of high atv's and 
>>> resolution
>>> for a long time and the information I find is conflicting.
>>>
>>> At what point do you realize full resolution?  100% ATV and 100%
>>> on the duel rate screen?   Is there an advantage in going to 130% ATV
>>> as far as resolution is concerned?
>>>
>>>
>>>
>>>
>>>> You should get your full surface travel (high rate) as close to 100% 
>>>> ATV
>>>> setting as possible.  ATV is a trap and if abused can lead to some 
>>>> really
>>>> bad control system installations.
>>>>
>>>> FHH
>>>> ----- Original Message ----- 
>>>> From: "Kelly Regan" <kelly.regan2 at verizon.net>
>>>> To: <NSRCA-discussion at lists.nsrca.org>
>>>> Sent: Wednesday, January 03, 2007 8:14 PM
>>>> Subject: [NSRCA-discussion] Aileron servo arm size and resolution?
>>>>
>>>>
>>>>
>>>>
>>>>> What length servo arms do you run on the ailerons?
>>>>>
>>>>> Why do I ask....
>>>>>
>>>>> When I first set up my Brio with the 9411 sa's on the ailerons
>>>>> I wanted to make sure I had full servo/radio resolution.
>>>>>
>>>>> I fly with a Futaba 9C and have CHP control arms on the ailerons.
>>>>>
>>>>> I set my ATV or End Point in the 9C to 130.  I used a standard JR
>>>>> servo wheel with the linkage set to the inner most hole.  In order to
>>>>> get the 1/2" aileron travel per the Brio manual I ended up with 120%
>>>>> duel rate.  It was my understanding that this is exactly what I 
>>>>> wanted.
>>>>> High ATV and high duel rate for full resolution?
>>>>>
>>>>> When Don flew my plane he said the aileron servo's seemed slow
>>>>> to him?  He was surprised to hear I had 9411sa's.    He suggested
>>>>> that I use longer servo arms and reduce the ATV to 100% to make
>>>>> the to keep the throw at 1/2" while increasing the surface speed.
>>>>>
>>>>> Tonight I installed the shortest Dubro arms with the linkage on the
>>>>> inner
>>>>> most hole.   That put the numbers at 100% ATV but I had to reduce
>>>>> the duel rate way down to 50% to get the same 1/2" throw.
>>>>>
>>>>> Am I wrong in assuming that cuts my resolution in half?
>>>>>
>>>>> I wanted to get you opinions on since I am now totally confused.
>>>>>
>>>>> What does a faster aileron speed do for me versus the loss of
>>>>> resolution?
>>>>> What is an acceptable loss in resolution to gain the speed?
>>>>>
>>>>> Thanks for you help
>>>>>
>>>>> -- 
>>>>> ______________________________________________
>>>>>
>>>>> Kelly Regan
>>>>> www.reganbrothers.com
>>>>> Home Page: http://mysite.verizon.net/vze6uror/
>>>>> ______________________________________________
>>>>>
>>>>> _______________________________________________
>>>>> NSRCA-discussion mailing list
>>>>> NSRCA-discussion at lists.nsrca.org
>>>>> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>>>>
>>>>>
>>>>>
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>>>>>
>>>>>
>>>>>
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>>>>
>>>>
>>> -- 
>>> ______________________________________________
>>>
>>> Kelly Regan
>>> www.reganbrothers.com
>>> Home Page: http://mysite.verizon.net/vze6uror/
>>> ______________________________________________
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>>
>>
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>
> -- 
> ______________________________________________
>
> Kelly Regan
> www.reganbrothers.com
> Home Page: http://mysite.verizon.net/vze6uror/
> ______________________________________________
>
> _______________________________________________
> NSRCA-discussion mailing list
> NSRCA-discussion at lists.nsrca.org
> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
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>
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