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GVT?

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careywf(at)sbcglobal.net
Guest

Posted: Sun May 24, 2009 10:21 am Post subject: GVT?

Hi  Everyone,

  

   A few questions regarding the GVT conducted in Germany on the 601XL:

  

    (1) Does anyone know what's involved in a ground vibration test (GVT), to detect among other things, aileron flutter? 

  

    (2) If not, does anyone know of a web site that describes the test? 

  

    (3) Was there more than one 601XL involved in the German GVT? 

  

    (4) Did the 601XL tested in Germany have hingless or hinged ailerons?

  

    (5) Someone on this site stated a month or so back that all of the 601XL accidents involving "suspected aileron flutter" were of the hingless design. Am I correct? If so, how "official" is that info? In the words, is the info regarding the hingless ailerons reflected in an accident report, or shown in photos?  I'm not arguing with the contributor, but I don't remember seeing any other comments along this line on this site.

  

 Walt Carey in Dayton, OH

 601XL 

 50%constructeded

Jabiru 3300A   

 [quote][b]

eddies

Joined: 20 Jun 2006
Posts: 40
Location: Australia

Posted: Sun May 24, 2009 1:15 pm Post subject: Re: GVT?

http://www.youtube.com/watch?v=0VMMVuVrweM



The video above expalains what was done.



The test where done using hinged ailerons



Cheers

Eddie

psm(at)att.net
Guest

Posted: Sun May 24, 2009 1:27 pm Post subject: GVT?

Hi Eddie,



Thank you for posting the link to the CH650 ground vibration test video.



Do you know if any testing was done of the plane we all have?  That 

would be the CH601XL.



Thanks,



Paul

XL grounded

At 02:15 PM 5/24/2009, you wrote:



 	  Quote: 	
		  



http://www.youtube.com/watch?v=0VMMVuVrweM



The video above expalains what was done.



The test where done using hinged ailerons



Cheers

Eddie

craig(at)craigandjean.com
Guest

Posted: Sun May 24, 2009 1:31 pm Post subject: GVT?

“Someone on this site stated a month or so back that all of the 601XL accidents involving "suspected aileron flutter" were of the hinge-less design”  

   

No, I don’t think this is correct. The Yuba City plane was built by AMD and had piano hinges. The post-crash photos show this (I’ve attached one). I believe there are hinged and hinge-less planes among the unexplained crashes.  

   

-- Craig  

     

From: owner-zenith601-list-server(at)matronics.com [mailto:owner-zenith601-list-server(at)matronics.com] On Behalf Of Walter Carey

 Sent: Sunday, May 24, 2009 12:19 PM

 To: 601XL builders

 Subject: GVT?  

  

              

Hi  Everyone,   

      

    

      

  A few questions regarding the GVT conducted in   Germany on the 601XL:   

      

    

      

   (1) Does anyone know what's involved in a   ground vibration test (GVT), to detect among other things, aileron flutter?    

      

    

      

   (2) If not, does anyone know of a web site   that describes the test?    

      

    

      

   (3) Was there more than one 601XL   involved in the German GVT?    

      

    

      

   (4) Did the 601XL tested in Germany have   hingless or hinged ailerons?   

      

    

      

   (5) Someone on this site stated a month or so   back that all of the 601XL accidents involving "suspected aileron   flutter" were of the hingless design. Am I correct? If so, how   "official" is that info? In the words, is the info regarding the   hingless ailerons reflected in an accident report, or shown in   photos?  I'm not arguing with the contributor, but I don't   remember seeing any other comments along this line on this site.   

      

    

      

Walt Carey in Dayton, OH   

      

601XL    

      

50%constructeded   

   

Jabiru 3300A            	  Quote: 	
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eddies

Joined: 20 Jun 2006
Posts: 40
Location: Australia

Posted: Sun May 24, 2009 5:32 pm Post subject: Re: GVT?

Hi Paul,



From what I understand the tests were done on the 650 which is basically the same aircraft as the 601XL (different canopy and rudder) so the test results would be valid regardless of the model, as they involved the wings and control surfaces. As far as I know these are the same on both the 601XL and 650 models.



Cheers

Eddie



Hi Eddie, 



Thank you for posting the link to the CH650 ground vibration test video. 



Do you know if any testing was done of the plane we all have? That 

would be the CH601XL. 



Thanks, 



Paul 

XL grounded

psm(at)att.net
Guest

Posted: Sun May 24, 2009 5:40 pm Post subject: GVT?

Hi Eddie,



Thanks for the reply.



As I understand it, the wings on the 650 are mounted differently from 

the 601.  I think the incidence angle is different or some such change.



Perhaps you are correct.  It might not matter which variant of the 

601 is tested.  There are so many minor variations that it would be 

impossible to test them all.  I suppose I consider the 650 as a model 

change rather than just another variant.



Paul

XL grounded

At 06:32 PM 5/24/2009, you wrote:



 	  Quote: 	
		  Hi Paul,



 >From what I understand the tests were done on the 650 which is 

 basically the same aircraft as the 601XL (different canopy and 

 rudder) so the test results would be valid regardless of the model, 

 as they involved the wings and control surfaces. As far as I know 

 these are the same on both the 601XL and 650 models.



Cheers

Eddie

Larry Hursh

Joined: 16 Feb 2008
Posts: 125
Location: Edwardsburg, MI (near Elkhart, IN)

Posted: Mon May 25, 2009 2:24 pm Post subject: GVT?

As I understand it, the wings on the 650 are mounted differently from 

the 601.  I think the incidence angle is different or some such change.



Paul

XL grounded

Paul and group,



I originally ordered the CH601XL fuselage kit but then upgraded to the CH650.  I already had the wing center section where the wings attach inside the fuselage.  There is no change where the wings attach to this center section.  Yes, the angle of that center section HAS been changed from 9 degrees to 7 degrees (forward).  



The one major change I can see is the REAR attachment plate.  The design has changed but the major thing is the thickness.  The older style rear attachment plate was about .065 thick.  It is now .120 or about double the thickness.  I was told it was increased because the "design was changed in order to allow the plate be be placed lower towards the bottom of the fuselage" (due to the angle being changed at the front of the wing).  



I NOT an Engineer and I can only (wildly) speculate if this change in thickness was for some other reason.  I will NOT state my opinion and let everyone else decide for themselves on this one, but I DO have my suspicions.



Blue skies to all,



Larry Hursh   



skyridersbn(at)yahoo.com

Edwardsburg, Michigan 

Zenith CH650 (N650LM Reserved)  Working on fuselage now     



Will be Corvair Powered  

Crankshaft already ground .010 - .010 Balanced and nitrited at Moldex     



I hope to someday be that person my dog thinks I am.....

_________________
Larry Hursh (N650LM Reserved)

"One rivet at a time......one day at a time.."

CH650 (Converted from CH601XL)
1/2 done with fuselage
will be Corvair Powered

MikeinPE

Joined: 02 Oct 2008
Posts: 13

Posted: Thu May 28, 2009 12:43 am Post subject: Re: GVT?

Hi Larry



Would you be so kind and let me know when you received your plans for the 650.  I got mine in January & it still shows the Root Doubler as .063"for the rear channel.  I'm referring to part 6W7- 2.  Is that the part that your plans have as .120"



"The one major change I can see is the REAR attachment plate. The design has changed but the major thing is the thickness. The older style rear attachment plate was about .065 thick. It is now .120 or about double the thickness. I was told it was increased because the "design was changed in order to allow the plate be be placed lower towards the bottom of the fuselage" (due to the angle being changed at the front of the wing)."



Keep on building!!!



Mike in Port Elizabeth, South Africa

ch650 scratchbuilder looking for a Corvair core!!!!

PatrickW

Joined: 27 Oct 2006
Posts: 380
Location: Fort Worth, Texas

Posted: Thu May 28, 2009 5:00 am Post subject: Re: GVT?

 	  careywf(at)sbcglobal.net wrote: 	
		   (5) Someone on this site stated a month or so back that all of the 601XL accidents involving "suspected aileron flutter" were of the hingless design. Am I correct? 	


No, just the opposite.  They were all of the piano hinged variety.



If I'm wrong, then I welcome a correction with supporting data. 



Does anyone have a concrete example of an XL having gone down that had the standard hingeless design?  If so, please share a photograph.



- Pat

Gig Giacona

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

Posted: Thu May 28, 2009 5:15 am Post subject: Re: GVT?

 	  PatrickW wrote: 	
		   	  careywf(at)sbcglobal.net wrote: 	
		   (5) Someone on this site stated a month or so back that all of the 601XL accidents involving "suspected aileron flutter" were of the hingless design. Am I correct? 	


No, just the opposite.  They were all of the piano hinged variety.

- Pat 	




That would have been me. I did some research and could not find an proof of an example of a hingeless 601XL in the 6 accident aircraft. I even asked over at ZBAG and they couldn't provide an example. I've since learned that there may be one but the info came second hand and and I've not been able to confirm.

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

craig(at)craigandjean.com
Guest

Posted: Thu May 28, 2009 6:43 am Post subject: GVT?

FWIW a builder visiting the ZAC booth at Oshkosh noticed the thicker plates

on the 650 and asked Caleb about it (I was standing there). Caleb said that

to shift the plate on the 650 vertically (as compared to the 601XL) to

changes the wing's angle of incidence the height of the plate had to be

reduced. The increase in thickness was to give the plate adequate strength

in its attachment to the fuselage. Caleb said it had nothing to do with

strengthening the attachment between the rear spar and the plate.



-- Craig



--

PatrickW

Joined: 27 Oct 2006
Posts: 380
Location: Fort Worth, Texas

Posted: Thu May 28, 2009 7:10 am Post subject: Re: GVT?

 	  craig(at)craigandjean.com wrote: 	
		  FWIW a builder visiting the ZAC booth at Oshkosh noticed the thicker plates on the 650 and asked Caleb about it (I was standing there). 

-- 	


Here's the picture I took of the plate:



http://picasaweb.google.com/Patrick.Hoyt/Zodiac650AtOshkosh#5243761730774797442



I was probably just one of several builders to ask about that, but if it was me that you were standing next to, then it was nice to meet you 



- Pat

Thruster87

Joined: 16 Apr 2008
Posts: 193
Location: Australia

Posted: Fri May 29, 2009 6:31 pm Post subject: Re: GVT?

The recent meetings between Zenair and German authorities (the DAeC and their DAR engineers as well as the BFU) were very productive with key steps taken towards re-establishing the good standing of the CH 601 XL aircraft throughout Europe. A very comprehensive presentation by the head of the GVT program that tested the aircraft made it very clear that the often suggested flutter is an exceedingly unlikely "smoking gun" to explain past accidents. The engineer in charge instead applauded Chris Heintz for the overall scores obtained by the Zodiac throughout the tests, as they were among the best ever seen in his lab. The results of the very thorough linear flutter analysis left no doubts in anyone's mind: "No tendency to flutter or divergence was found within the flight envelope of the CH 601 XL". This included tests from minimum to maximum take-off weight; with fixed as well as free controls; with control cable tensions varying from well below 10 lbs. to over 40 lbs, and with standard as well as overweight control surfaces (i.e. possibly due to excessive paint in the "real world"); all from sea level to over 15,000 feet and to speeds well above 400 km/h.



In order to ensure accurate results, all tests were carried out on two different Zodiac aircraft. The significance of the flap stops called-for as part of the regular design was confirmed. The aircraft which did not at first have these installed showed less satisfactory results than Zenair's own standard demo plane (with stops) which was one of the tested planes. Zenair will be issuing a Service Letter very shortly calling for owners/pilots to check their flap stops (and to install them prior to further flight operations if these have not been previously fitted). By the end of the tests, both aircraft (a classic CH 601 XL and the newer CH 650 E) presented the same consistent results: No tendency to flutter.

Also during this GVT testing process, it was noticed that the German-registered CH 601 XL on which the tests were conducted did not have part of the aileron-stop structure which was an integral part of the CH 601 XL at the time of German certification. Zenair has been asked by the DAeC to issue a Service Letter addressing this potential discrepancy for German-registered CH 601 XL; the DAeC will be issuing its own AD shortly to ensure the aircraft's ongoing compliance with LTF-UL certification.



Many questions were answered by the flutter expert after his presentation to German authorities; his answers and ample GVT data successfully satisfied those present that flutter was a non-issue for the Zenair Zodiac design. "The complete ground vibration tests (GVT) just completed were conducted to natural frequencies well over 70 Hz. This clearly demonstrates that the standard Zodiac design is flutter-free within (and well beyond) the entire range of its flight envelope" said Chris Heintz, who also attended the meetings.

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