[NSRCA-discussion] Pull-Pull

[Fred Huber]

Someone mentioned adding a tensioner....

If the tension is high enough... no slack will get introduced.  But hinge 
load could be a problem requiring a very heavy (possibly ball bearing) hinge 
right at the control horn. (depending on how much tension is needed to 
overcome maximum flight load)

In a way you have tensioners already... they are called grommets.  As the 
servo gets loaded it can shift.  Squeeze the pull-pull cables together close 
to the servo arm and watch what loading the system does.

----- Original Message ----- 
From: "Dave Burton" <burtona at bellsouth.net>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Wednesday, January 10, 2007 10:23 AM
Subject: Re: [NSRCA-discussion] Pull-Pull


> Maybe I just don't get it, but any kind of tensioner or sliding servo is
> just going to introduce slack into the rudder or elevator system when 
> under
> load. Why do you want that? Seems to me you would want the cables as rigid
> as possible. That's how I've always set them up.
>
> -----Original Message-----
> From: nsrca-discussion-bounces at lists.nsrca.org
> [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Fred Huber
> Sent: Wednesday, January 10, 2007 10:19 AM
> To: NSRCA Mailing List
> Subject: Re: [NSRCA-discussion] Pull-Pull
>
>
> Tensioner... servo mounted on sliding tray (we should al remember how to 
> do
> that from doing elevons without computer mixing... CF tubes instead of the
> old nyrod on wire inherant slop should dissapear.) with a spring to pull 
> the
> servo in the opposed direction to the pull-pull wires.  (simplest
> mechanicly... not sure if its the lightest)
>
> You could play with the idea...
>
> Run pull-pull back to a free pulley that is pulled by the tensioner 
> spring,
> taking the side load off the servo.  Slightly more complex and adds the
> weight of the pulley, but should reduce servo wear.
>
> If you like having a bellcrank to adjust travel relationshoip between 
> servo
> and pull-pull... mount the bellcrank on the sliding servo tray.
>
>
> ----- Original Message -----
> From: "Jay Marshall" <lightfoot at sc.rr.com>
> To: "'NSRCA Mailing List'" <nsrca-discussion at lists.nsrca.org>
> Sent: Wednesday, January 10, 2007 9:07 AM
> Subject: Re: [NSRCA-discussion] Pull-Pull
>
>
>> Well then, no logical reason. All, including myself, agree that it works;
>> I
>> also use it. It would also seem that if a tensioner is used, as with
>> timing
>> belts on a car, that the
>> trim-change-with-temperature-due-to-fuse-expansion
>> problem would disappear.
>>
>>
>> -----Original Message-----
>> From: nsrca-discussion-bounces at lists.nsrca.org
>> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Ron Van
>> Putte
>> Sent: Wednesday, January 10, 2007 9:15 AM
>> To: NSRCA Mailing List
>> Subject: Re: [NSRCA-discussion] Pull-Pull
>>
>>
>> On Jan 10, 2007, at 8:09 AM, Gene Maurice wrote:
>>
>>> I have been using pull-pull on elevators for 15 years with great
>>> success. It
>>> is a little more difficult to setup, but once done, it is
>>> completely idiot proof.
>>
>>
>> Gene - I'm absolutely sure someone will say, "Well, you should know",
>> but not me.  <VBG>
>>
>> Ron Van Putte
>>
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