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Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Tue Mar 18, 2008 11:52 am Post subject: Re: Great News!

Sabrina, when did I ever make any comment about either your age or gender? You know better and I'm quite sure you've not only heard far worse language than I used here at the airport. 



But to the important stuff.  Where did you get the info you posted below? 

 	  Sabrina wrote: 	
		  I have it on good sources that: 



NO MODIFICATION TO THE WING will be suggested by CH. 



To obtain insurance I may be required to comply with an upcoming Zenith letter and replace my rear lower nylon elevator stops with new ones that allow only 15 degrees of downward movement as opposed to the 27-30 degrees specified in 6-S-4.



I am not doing ANYTHING until I get that letter since I have no clue how stall recovery will be affected.    If I can obtain insurance without the modification, I will not make the modification at this point .  Proper pilot training and a flexible stick quadrant seems like the better option to me at this point in time, but hey, as Gig points out, I am only 14 and I am a girl.

(Gig your recent comments almost caused my dad to bar me from this forum.)



Changing the deflection as per this proposed letter will make W&B calculations all the more critical!



Measure twice, then measure again.  



DO NOT QUOTE   DO NOT ARCHIVE  FEEL FREE TO CHIME IN

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_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

jmaynard

Joined: 27 Feb 2008
Posts: 394
Location: Fairmont, MN (FRM)

Posted: Tue Mar 18, 2008 12:19 pm Post subject: Re: Great News!

Something I don't understand: Why are they concentrating on downward movement of the elevator? The failures have been of the wings folding upward, right? In at least one case (the British accident), the failure occurred during a pull up from a high speed low pass, which would involve an upward movement of the elevator.



If the problem is the wings folding upward, it would seem to me that that happens when the elevator is deflected upward, causing the wings to assume a higher angle of attack, increasing their lift and pulling the fuselage upward at the spar attachment, thus increasing the load on the spar and its attachments. Thus, limiting downward travel of the elevator seems to be not very helpful.



I don't think that it'd cause problems with stall recovery, especially since the Zodiac I flew recovered simply by relaxing the back pressure on the stick,  but it doesn't seem like it'll cause the desired effect, either. What am I missing?

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_________________
Jay Maynard, K5ZC
AMD Zodiac XLi N55ZC

rhodes1

Joined: 15 Feb 2008
Posts: 20
Location: Us

Posted: Tue Mar 18, 2008 12:24 pm Post subject: Great News!

Hi

What is a flexible stick quadrant and purpose

Thanks Don

---

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planecrazydld(at)yahoo.co
Guest

Posted: Tue Mar 18, 2008 12:35 pm Post subject: Great News!

HI Sabrina;



I keep floating anti-servo geometry for the elevator tab but no biters yet - and I am not continuing my build for personal reasons. What is your take on the centering forces that anti-servo geometry to the tab would generate and why could it not be combined with the restricted down travel stop?



I like the way you think and that is why I am digging here.



Sabrina <chicago2paris(at)msn.com> wrote:[quote] --> Zenith-List message posted by: "Sabrina" 



I have it on good sources that: 



NO MODIFICATION TO THE WING will be suggested by CH. 



To obtain insurance I may be required to comply with an upcoming Zenith letter and replace my rear lower nylon elevator stops with new ones that allow only 15 degrees of downward movement as opposed to the 27-30 degrees specified in  [quote][b]

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MHerder

Joined: 11 Feb 2008
Posts: 143
Location: Fort Worth TX

Posted: Tue Mar 18, 2008 1:13 pm Post subject: Re: Great News!

I pondered this myself, but after thinking about it a little more I could imagine that the downward failure mode and buckling that would occur would be then very quickly and violently be reversed and ripped backwards due to the drag and lift on the wing.  Once buckling occurs and the aluminum has yielded, and the web has buckled, there is no going back...



I'd like for someone with a better understanding of aeronautical engineering to comment on what I just suggested as a possible failure mode...



 	  jmaynard wrote: 	
		  Something I don't understand: Why are they concentrating on downward movement of the elevator? The failures have been of the wings folding upward, right? In at least one case (the British accident), the failure occurred during a pull up from a high speed low pass, which would involve an upward movement of the elevator.



If the problem is the wings folding upward, it would seem to me that that happens when the elevator is deflected upward, causing the wings to assume a higher angle of attack, increasing their lift and pulling the fuselage upward at the spar attachment, thus increasing the load on the spar and its attachments. Thus, limiting downward travel of the elevator seems to be not very helpful.



I don't think that it'd cause problems with stall recovery, especially since the Zodiac I flew recovered simply by relaxing the back pressure on the stick,  but it doesn't seem like it'll cause the desired effect, either. What am I missing?

- The Matronics Zenith-List Email Forum -

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_________________
Zodiac 601 HD
Jabiru 3300
Wood Sensinich 64x47
Finally Flying

psm(at)ATT.NET
Guest

Posted: Tue Mar 18, 2008 1:14 pm Post subject: Great News!

Hi Sabrina,



I just have two questions:



1)  How would insurance folks know about elevator stops on a Zodiac 

XL?  All the insurance guys I have talked to can barely spell EXPERIMENTAL.



2)  I thought you had to be a lot older than 14 to legally fly 

powered planes, like 18 maybe.   Has that changed?



Paul

XL fuselage

Well over 14 (and 41 too)

At 12:45 PM 3/18/2008, you wrote:



 	  Quote: 	
		  I have it on good sources that:



NO MODIFICATION TO THE WING will be suggested by CH.



To obtain insurance I may be required to comply with an upcoming 

Zenith letter and replace my rear lower nylon elevator stops with 

new ones that allow only 15 degrees of downward movement as opposed 

to the 27-30 degrees specified in 6-S-4.



I am not doing ANYTHING until I get that letter since I have no clue 

how stall recovery will be affected.    If I can obtain insurance 

without the modification, I will not make the modification at this 

point .  Proper pilot training and a flexible stick quadrant seems 

like the better option to me at this point in time, but hey, as Gig 

points out, I am only 14 and I am a girl.

(Gig your recent comments almost caused my dad to bar me from this forum.)



Changing the deflection as per this proposed letter will make W&B 

calculations all the more critical!



Measure twice, then measure again.



DO NOT QUOTE   DO NOT ARCHIVE  FEEL FREE TO CHIME IN

- The Matronics Zenith-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Tue Mar 18, 2008 1:26 pm Post subject: Great News!

The legal age is 16 to solo in the U. S. Apparently, it's 14 in Canada.



Paul Mulwitz wrote:

 	  Quote: 	
		   

 

 Hi Sabrina,

 

 I just have two questions:

 

 1)  How would insurance folks know about elevator stops on a Zodiac XL?  

 All the insurance guys I have talked to can barely spell EXPERIMENTAL.

 

 2)  I thought you had to be a lot older than 14 to legally fly powered 

 planes, like 18 maybe.   Has that changed?

 

 Paul

 XL fuselage

 Well over 14 (and 41 too)

 

 

 At 12:45 PM 3/18/2008, you wrote:

 

> I have it on good sources that:

>

> NO MODIFICATION TO THE WING will be suggested by CH.

>

> To obtain insurance I may be required to comply with an upcoming 

> Zenith letter and replace my rear lower nylon elevator stops with new 

> ones that allow only 15 degrees of downward movement as opposed to the 

> 27-30 degrees specified in 6-S-4.

>

> I am not doing ANYTHING until I get that letter since I have no clue 

> how stall recovery will be affected.    If I can obtain insurance 

> without the modification, I will not make the modification at this 

> point .  Proper pilot training and a flexible stick quadrant seems 

> like the better option to me at this point in time, but hey, as Gig 

> points out, I am only 14 and I am a girl.

> (Gig your recent comments almost caused my dad to bar me from this 

> forum.)

>

> Changing the deflection as per this proposed letter will make W&B 

> calculations all the more critical!

>

> Measure twice, then measure again.

>

-- 
	


Bryan Martin

Zenith 601XL N61BM

Ram Subaru, Stratus redrive

Do Not Archive

- The Matronics Zenith-List Email Forum -

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_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

notsew_evets(at)frontiern
Guest

Posted: Tue Mar 18, 2008 3:18 pm Post subject: Great News!

Wishing I was 16................

---

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planecrazydld(at)yahoo.co
Guest

Posted: Wed Mar 26, 2008 3:24 pm Post subject: Great News!

http://en.wikipedia.org/wiki/Servo_tab

   

  Hi Sabrina;

   

  I did not forget your request - I just have not had the time to search adequately for a useful response.

   

  The Thorp T-18 and the Volksplane II both used antiservo tabs on the pitch control. I have a set of VPII drawings somewhere but the tab is strictly anti-servo and not combined trim and atni-servo. I believe that the T-18 was coupled.

   

  The basic concept for coupling is that the sati servo is geared diagonally by a horn from one face of the tab to the reference base on the other face of the stabilizer of fuselage such that when the elevator/stabilator moves nose down/trailing edge up, the tab is driven even further tin the same direction of deflection thus providing a counter force attempting to drive the control surface back towards zero  deflection. To add trim tp this concept, the fixed reference base for the tab pushrod is made movable so the the centering bias is affected.



Sabrina <chicago2paris(at)msn.com> wrote:

  [quote]--> Zenith-List message posted by: "Sabrina" 



Can you find me a design photo of an anti-servo tab like you are talking about (for an XL with a fixed horizontal stabilizer and an elevator where a single tab cannot be placed across the entire surface due to interference by the rudder as in the Zenith)? (You would need to cross-tie the two tabs, no?)



Per the PILOT’S HANDBOOK of Aeronautical Knowledge 2003, an antiservo tab moves in the same direction as the trailing edge of the stabilator. The antiservo tab also functions as a trim tab to relieve control pressures and helps maintain the stabilator in the desired position.  [quote][b]

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