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601XL Wing Flutter

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JAPhillipsGA(at)AOL.COM
Guest

Posted: Fri Jan 26, 2007 10:33 pm Post subject: 601XL Wing Flutter

Dear Thread Friends, I went flying this afternoon. Took a fellow with me and just wanted an hour in the clear blue. Conditions were perfect, clear, cool and only a slight wind. The only big thing around much to see nearby is Lake Juliette which has a big coal fired power station in the middle. Three huge steam towers that look like a nuclear power station. We flew around the lake about two miles away at 5000 feet so my pal could get a good look see. On the down wind side we flew into an invisible killer. We were doing above 140 when we flew into it. Instantly the left wing fluttered at a fast pitch, aileron and all and it looked to be moving maybe two inched up and down. I figured a couple seconds would break it off. I didn't have time to look around the passenger to see if the right wing was fluttering, but I suspect it was. I chopped power and did a hard diving wing over to the left and out of it. The flutter sound was great even over my Lightspeed AN system and the whole thing probably last maybe 5 or 6 seconds. I regained control out of the snap dive, maxing above 170 and flew slow and easy back to the field before I tested the controls. Everything felt okay and I could see no wrinkles in the top skin so I landed. Didn't really have much choice. Upon inspection I found no sign of stress, no skin deform, no paint cracked around rivets, nothing. I will take off all inspection panels for a close inspection this weekend and check bolts, controls, etc., but I cannot believe such a prolonged violent movement of the wing did not damage something other than my pride. Two things learned. Don't fly anywhere near a power station. Even at 5000 feet and miles away the invisible heat rises and is most extreme. Maybe intensified in cold weather. The other thing is the XL is very, very tough. Oh, there is a third thing. How could I have been so stupid not to know the first thing !!  I am interested though in knowing why the wings fluttered in this thermal? What theory of air dynamics would cause this extreme reaction? Was is just the level of heat and speed the invisible air was streaming past? This was my 90th flight in her and she made me proud again. Best regards to you all, 

 Bill of Georgia 

 N505WP

 601XL-3300   [quote][b]

p.mulwitz(at)worldnet.att
Guest

Posted: Sat Jan 27, 2007 2:41 am Post subject: 601XL Wing Flutter

Hi Bill,



 That was a truly shocking story.  I can't help but connect the dots with your flight and the recent events of XL's falling out of the sky.



 I wonder if you could answer a couple of questions:

 1.  Which aileron hinges do you have?

 2.  Do you have the center stick?

 3.  Did you build from kit or scratch?



 If you were actually experiencing flutter, then I would have thought slowing down would be the way out.  When you increased speed to stop the vibration, did it occur again as you slowed down?



 I think I'll take up knitting instead of airplane building . ..



 Paul

 XL fuselage

 do not archive



 At 10:31 PM 1/26/2007, you wrote:

  	  Quote: 	
		  Dear Thread Friends, I went flying this afternoon. Took a fellow with me and just wanted an hour in the clear blue. Conditions were perfect, clear, cool and only a slight wind. The only big thing around much to see nearby is Lake Juliette which has a big coal fired power station in the middle. Three huge steam towers that look like a nuclear power station. We flew around the lake about two miles away at 5000 feet so my pal could get a good look see. On the down wind side we flew into an invisible killer. We were doing above 140 when we flew into it. Instantly the left wing fluttered at a fast pitch, aileron and all and it looked to be moving maybe two inched up and down. I figured a couple seconds would break it off. I didn't have time to look around the passenger to see if the right wing was fluttering, but I suspect it was. I chopped power and did a hard diving wing over to the left and out of it. The flutter sound was great even over my Lightspeed AN system and the whole thing probably last maybe 5 or 6 seconds. I regained control out of the snap dive, maxing above 170 and flew slow and easy back to the field before I tested the controls. Everything felt okay and I could see no wrinkles in the top skin so I landed. Didn't really have much choice. Upon inspection I found no sign of stress, no skin deform, no paint cracked around rivets, nothing. I will take off all inspection panels for a close inspection this weekend and check bolts, controls, etc., but I cannot believe such a prolonged violent movement of the wing did not damage something other than my pride. Two things learned. Don't fly anywhere near a power station. Even at 5000 feet and miles away the invisible heat rises and is most extreme. Maybe intensified in cold weather. The other thing is the XL is very, very tough. Oh, there is a third thing. How could I have been so stupid not to know the first thing !!  I am interested though in knowing why the wings fluttered in this thermal? What theory of air dynamics would cause this extreme reaction? Was is just the level of heat and speed the invisible air was streaming past? This was my 90th flight in her and she made me proud again. Best regards to you all, 

 Bill of Georgia 

 N505WP

 601XL-3300 	
 

 ---------------------------------------------

 Paul Mulwitz

 32013 NE Dial Road

 Camas, WA 98607

 ---------------------------------------------

     [quote][b]

n701rr(at)yahoo.com
Guest

Posted: Sat Jan 27, 2007 3:23 am Post subject: 601XL Wing Flutter

WOW Bill,

   

  Thanks for sharing this.  That power plant was in the memory bank of my HUD!  No more!

  Glad you and passenger are OK and I hope it wasn't their first flight!  Let me know if you need my help with anything INCLUDING laundry.

   

  Low & slow...Rick

   

  do not archive



JAPhillipsGA(at)aol.com wrote:

  [quote]Dear Thread Friends, I went flying this afternoon. Took a fellow with me and just wanted an hour in the clear blue. Conditions were perfect, speed the invisible air was streaming past? This was my 90th flight in her and she made me proud again. Best regards to you all, 

Bill of Georgia 

N505WP

601XL-3300 [quote][b]

barcusc(at)comcast.net
Guest

Posted: Sat Jan 27, 2007 5:58 am Post subject: 601XL Wing Flutter

I know Chris Heinz is retired but I bet he would be  quick to respond to a serious question like this. I suggest you contact ZAC and  ask them to get Chris's input, I wouldn't accept their explanation if Chris  wasn't involved. Thank God you were able to get out of the situation but that  does open up questions about the right response and I think Chris's opinion on  this would be helpful as well. I appreciate your posting, all of us can learn  something from this.

  

 Regards:

  

 Clyde Barcus

 601 XL 

  

 [quote]   ---

planejim(at)bellsouth.net
Guest

Posted: Sat Jan 27, 2007 6:06 am Post subject: 601XL Wing Flutter

Hey Bill,

  

 Sounds scary! Glad you are OK. Although it was  years ago ( first off I'm NOT a trained test pilot ) I was involved in some  actual flutter problems involving a Midget Mustang I built by a friend and  latter did flutter tests in a Mustang II built by another friend.

  

 When we experienced the flutter with the MM  I  ( at about 180 mph ) we consulted an old friend who knew Dave Long ( the  designer of the MM I ) and picked his brain. One thing he said is if you  experience flutter you have mere seconds to SLOW DOWN and the best way to do  that is to reduce power and pull the airplane up ( I noticed you dove and  increased speed but got out of it ). This procedure helped us with the MM I.  What we found with this airplane was an accumulation of built in slop in the  aileron control system. This system was all push rods and bellcranks and  the builder had just drilled all the holes ( did not ream ) and used  AN Standard bolts. I found this quickly by haveing the builder grasp one  aileron while I moved the other aileron up and down better than a 1/4" at  the trailing edge. Remeber this is a 200 mph plus airplane. We went to NAS and  oversized bolts and tightened up the slop. This DIDN'T cure the flutter though.  What we found then was that when he filled the counterweight tubes that  were mounted forward of the hinge line with lead, he didn't get the tubes full  as the lead solidified as he poured it in and left many air spaces inside the  tube. We corrected that and the flutter problem went away. Probably both  problems contributed to the flutter.

  

 In the Mustang II we were doing flutter test in  the 225 230 mph range by increasing the speed by 1 mph increments and never  had a problem, but we were ready to slow it down if one did  arise.

  

 I know John from AMD tested for flutter when he  did your test flight and he said nothing about it when he landed. You might call  him and ask what max speed he uses when testing.

  

 Not being an aerodynamicist ( spelling? ) I don't  know the cause for your encounter but just maybe it has something to do with the  fact that we don't use balanced controls on these Zenith airplanes and a weird  air pattern that you encountered because of the heat from the power plant. I've  flown over large fires on the ground, as I'm sure you and others have in the  past and experienced some pretty rough air but not FLUTTER. 

  

 In your case, if it was unbalanced controls, it  seems that when you dove to 170, it should have made it worse. Do the "grab  one aileron and try to move the other test" and see what you find. Otherwise,  DON'T fly near the power plant any more! I've been tempted to fly over to that  same place but since 9-11 I stay away from all power plants.

  

 Let me know if I can help and also what you  find.

  

 Jim Hoak 

 [quote]   ---

n801bh(at)netzero.com
Guest

Posted: Sat Jan 27, 2007 6:26 am Post subject: 601XL Wing Flutter

Control flutter is a function of speed, If I ever encounter it I will pull off the power and  instantly climb to bleed off excess speed. I am curious why you dove and sped up?? 

do not archive

Ben Haas

N801BH

www.haaspowerair.com



-- "Jim Hoak" <planejim(at)bellsouth.net> wrote:

 Hey Bill,

  

 Sounds scary! Glad you are OK. Although it was years ago ( first off I'm NOT a trained test pilot ) I was involved in some actual flutter problems involving a Midget Mustang I built by a friend and latter did flutter tests in a Mustang II built by another friend.

  

 When we experienced the flutter with the MM I  ( at about 180 mph ) we consulted an old friend who knew Dave Long ( the designer of the MM I ) and picked his brain. One thing he said is if you experience flutter you have mere seconds to SLOW DOWN and the best way to do that is to reduce power and pull the airplane up ( I noticed you dove and increased speed but got out of it ). This procedure helped us with the MM I. What we found with this airplane was an accumulation of built in slop in the aileron control system. This system was all push rods and bellcranks and the builder had just drilled all the holes ( did not ream ) and used AN Standard bolts. I found this quickly by haveing the builder grasp one aileron while I moved the other aileron up and down better than a 1/4" at the trailing edge. Remeber this is a 200 mph plus airplane. We went to NAS and oversized bolts and tightened up the slop. This DIDN'T cure the flutter though. What we found then was that when he filled the counterweight tubes that were mounted forward of the hinge line with lead, he didn't get the tubes full as the lead solidified as he poured it in and left many air spaces inside the tube. We corrected that and the flutter problem went away. Probably both problems contributed to the flutter.

  

 In the Mustang II we were doing flutter test in the 225 230 mph range by increasing the speed by 1 mph increments and never had a problem, but we were ready to slow it down if one did arise.

  

 I know John from AMD tested for flutter when he did your test flight and he said nothing about it when he landed. You might call him and ask what max speed he uses when testing.

  

 Not being an aerodynamicist ( spelling? ) I don't know the cause for your encounter but just maybe it has something to do with the fact that we don't use balanced controls on these Zenith airplanes and a weird air pattern that you encountered because of the heat from the power plant. I've flown over large fires on the ground, as I'm sure you and others have in the past and experienced some pretty rough air but not FLUTTER. 

  

 In your case, if it was unbalanced controls, it seems that when you dove to 170, it should have made it worse. Do the "grab one aileron and try to move the other test" and see what you find. Otherwise, DON'T fly near the power plant any more! I've been tempted to fly over to that same place but since 9-11 I stay away from all power plants.

  

 Let me know if I can help and also what you find.

  

 Jim Hoak 

 [quote] ---

JAPhillipsGA(at)aol.com
Guest

Posted: Sat Jan 27, 2007 7:06 am Post subject: 601XL Wing Flutter

Ben, maybe I did not explain well, but it was not control flutter. The aileron did not move independent of the wing. What occurred is the whole wing fluttered with aileron moving with it., best regards, Bill    [quote][b]

PatrickW

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

Posted: Sat Jan 27, 2007 10:44 pm Post subject: Re: 601XL Wing Flutter - Not...

Sheesh.  I gotta chime in here...



This is normal and has nothing to do with "flutter".  I'd file this one right along side all the "twitchy" nonsense that was going around a few months ago.



The guy hit a strong thermal due to rising heat off the steam stacks.  Simple as that.  I see this regularly in my Piper Warrior.



The downwind 45 entry to my home airport runs right over the top of an oil refinery.  Lots of heat.  Always enough to bump you as you go over, and once it was enough to put me nearly on my side.  



You have to expect that sort of thing when flying over a large heat source. 



Regarding the wings bouncing - watch the normal flex of your wings (or look out the window next time you're on an airliner).  Push & pull on that thing in your hands and watch what your wings do...



Suggestion:  go back and fly over that power plant again.  Go high and slow, watch your altimeter, and expect some bumps.  It won't be so bad now that you can anticipate what's going to happen.  Seriously, give this a shot.



- Patrick

naumuk(at)alltel.net
Guest

Posted: Sun Jan 28, 2007 8:52 am Post subject: 601XL Wing Flutter

All-

    Since I was responsible for the observation of Dutch Roll in the YouTube 

clip refered to here, let me make a public retraction. Other YouTube clips 

have shown  smoothly flown 601 landing patterns. It seems the "Twitchiness" 

I observed was due to PIO, and is not to be confused with the no BS Dutch 

Roll inherent in an A36 Bonanza.

Bill Naumuk

HDS Fuselage

Townville, Pa

---

ggower_99(at)yahoo.com
Guest

Posted: Tue Jan 30, 2007 9:14 am Post subject: 601XL Wing Flutter

Hello all,



Dont panic!  This is simple severe turbulence by a big thermal.   Normally a "bumpy" ride is not that way because in this case the heat is concetrated a lot.  Like a fly  flying over a torch welder   



Just to make shure,  lets remember, in the first signs of turbulence,  slow a little the cruise speed,  if it get severe, slow to manuver speed and keep alert not to get cought in a high angle attitude,  "Ride" the turbulence with the controls as gently as possible...



Saludos

Gary Gower.

Paul Mulwitz <p.mulwitz(at)worldnet.att.net> wrote:[quote]   Hi Bill,



 That was a truly shocking story.  I can't help but connect the dots with your flight and the recent events of XL's falling out of the sky.



 I wonder if you could answer a couple of  questions:

 1.  Which aileron hinges do you have?

 2.  Do you have the center stick?

 3.  Did you build from kit or scratch?



 If you were actually experiencing flutter, then I would have thought slowing down would be the way out.  When you increased speed to stop the vibration, did it occur again as you slowed down?



 I think I'll take up knitting instead of airplane building . ..



 Paul

 XL fuselage

 do not archive



 At 10:31 PM 1/26/2007, you wrote:

  	  Quote: 	
		  Dear Thread Friends, I went flying this afternoon. Took a fellow with me and just wanted an hour in the clear blue. Conditions were perfect, clear, cool and only a slight wind. The only big thing around much to see nearby is Lake Juliette which has a big coal fired power station in the middle. Three huge steam towers that look like a nuclear power station. We flew around the lake about two miles away at  5000 feet so my pal could get a good look see. On the down wind side we flew into an invisible killer. We were doing above 140 when we flew into it. Instantly the left wing fluttered at a fast pitch, aileron and all and it looked to be moving maybe two inched up and down. I figured a couple seconds would break it off. I didn't have time to look around the passenger to see if the right wing was fluttering, but I suspect it was. I chopped power and did a hard diving wing over to the left and out of it. The flutter sound was great even over my Lightspeed AN system and the whole thing probably last maybe 5 or 6 seconds. I regained control out of the snap dive, maxing above 170 and flew slow and easy back to the field before I tested the controls. Everything felt okay and I could see no wrinkles in the top skin so I landed. Didn't really have much choice. Upon inspection I found no sign of stress, no skin deform, no paint cracked around rivets, nothing. I will take off all  inspection panels for a close inspection this weekend and check bolts, controls, etc., but I cannot believe such a prolonged violent movement of the wing did not damage something other than my pride. Two things learned. Don't fly anywhere near a power station. Even at 5000 feet and miles away the invisible heat rises and is most extreme. Maybe intensified in cold weather. The other thing is the XL is very, very tough. Oh, there is a third thing. How could I have been so stupid not to know the first thing !!  I am interested though in knowing why the wings fluttered in this thermal? What theory of air dynamics would cause this extreme reaction? Was is just the level of heat and speed the invisible air was streaming past? This was my 90th flight in her and she made me proud again. Best regards to you all, 

 Bill of Georgia 

 N505WP

 601XL-3300 	
  8:00? 8:25? 8:40? [url= http://tools.search.yahoo.com/shortcuts/?fr=oni_on_mail&#news] Find a flick[/url] in no time

 with the[url= http://tools.search.yahoo.com/shortcuts/?fr=oni_on_mail&#news]Yahoo! Search movie showtime shortcut.[/url] [quote][b]

meltonoso(at)cox.net
Guest

Posted: Tue Jan 30, 2007 11:51 am Post subject: 601XL Wing Flutter

Just to feel better about things, you might want to check the torque on your spar bolts, and maybe even pull one and make sure that the tolerance on the bolt is as close as it should be going through the spar box. Alan Melton  

         

  

From: owner-zenith-list-server(at)matronics.com [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of Gary Gower

 Sent: Tuesday, January 30, 2007 12:13 PM

 To: zenith-list(at)matronics.com

 Subject: Re: 601XL Wing Flutter  

  

   

Hello all,

 

 Dont panic!  This is simple severe turbulence by a big thermal.   Normally a "bumpy" ride is not that way because in this case the heat is concetrated a lot.  Like a fly  flying over a torch welder   

 

 Just to make shure,  lets remember, in the first signs of turbulence,  slow a little the cruise speed,  if it get severe, slow to manuver speed and keep alert not to get cought in a high angle attitude,  "Ride" the turbulence with the controls as gently as possible...

 

 Saludos

 Gary Gower.

 

 

 Paul Mulwitz <p.mulwitz(at)worldnet.att.net> wrote:  

Hi Bill,

 

 That was a truly shocking story.  I can't help but connect the dots with your flight and the recent events of XL's falling out of the sky.

 

 I wonder if you could answer a couple of questions:

 1.  Which aileron hinges do you have?

 2.  Do you have the center stick?

 3.  Did you build from kit or scratch?

 

 If you were actually experiencing flutter, then I would have thought slowing down would be the way out.  When you increased speed to stop the vibration, did it occur again as you slowed down?

 

 I think I'll take up knitting instead of airplane building . ..

 

 Paul

 XL fuselage

 do not archive

 

 At 10:31 PM 1/26/2007, you wrote:

 

   

Dear Thread Friends, I went flying this afternoon. Took a fellow with me and just wanted an hour in the clear blue. Conditions were perfect, clear, cool and only a slight wind. The only big thing around much to see nearby is Lake Juliette which has a big coal fired power station in the middle. Three huge steam towers that look like a nuclear power station. We flew around the lake about two miles away at 5000 feet so my pal could get a good look see. On the down wind side we flew into an invisible killer. We were doing above 140 when we flew into it. Instantly the left wing fluttered at a fast pitch, aileron and all and it looked to be moving maybe two inched up and down. I figured a couple seconds would break it off. I didn't have time to look around the passenger to see if the right wing was fluttering, but I suspect it was. I chopped power and did a hard diving wing over to the left and out of it. The flutter sound was great even over my Lightspeed AN system and the whole thing probably last maybe 5 or 6 seconds. I regained control out of the snap dive, maxing above 170 and flew slow and easy back to the field before I tested the controls. Everything felt okay and I could see no wrinkles in the top skin so I landed. Didn't really have much choice. Upon inspection I found no sign of stress, no skin deform, no paint cracked around rivets, nothing. I will take off all inspection panels for a close inspection this weekend and check bolts, controls, etc., but I cannot believe such a prolonged violent movement of the wing did not damage something other than my pride. Two things learned. Don't fly anywhere near a power station. Even at 5000 feet and miles away the invisible heat rises and is most extreme. Maybe intensified in cold weather. The other thing is the XL is very, very tough. Oh, there is a third thing. How could I have been so stupid not to know the first thing !!  I am interested though in knowing why the wings fluttered in this thermal? What theory of air dynamics would cause this extreme reaction? Was is just the level of heat and speed the invisible air was streaming past? This was my 90th flight in her and she made me proud again. Best regards to you all, 

 Bill of Georgia 

 N505WP

 601XL-3300        size=1 width="100%" align=center>  

  

8:00? 8:25? 8:40? [url=%0d%0ahttp:/tools.search.yahoo.com/shortcuts/?fr=oni_on_mail&#news]Find a flick[/url] in no time

 with the[url=%0d%0ahttp:/tools.search.yahoo.com/shortcuts/?fr=oni_on_mail&#news]Yahoo! Search movie showtime shortcut.[/url]    	  Quote: 	
		    http://www.matronics.com/Navigator?Zenith-List 	
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        [quote][b]

David X

Joined: 10 Jan 2006
Posts: 154
Location: Princeton, NJ, USA

Posted: Tue Jan 30, 2007 9:37 pm Post subject: Re: 601XL Wing Flutter

Still curious what type of aeileron hinges you have.

_________________
Zodiac 601 XL - CZAW Built - Rotax 912S
DO NOT ARCHIVE

japhillipsga(at)AOL.COM
Guest

Posted: Wed Jan 31, 2007 7:30 am Post subject: 601XL Wing Flutter

David, the aileron does not have a hinge. I used the standard ZAC solid skin flex mode. Duel stick controls, Best regards, Bill

   do not archive 

    

  

 --

David X

Joined: 10 Jan 2006
Posts: 154
Location: Princeton, NJ, USA

Posted: Fri Nov 14, 2008 6:26 pm Post subject: Re: 601XL Wing Flutter

I wonder if you have verified the cable tensions for your ailerons. This seems to be a focus of concern with the NTSB regarding aileron flutter.

_________________
Zodiac 601 XL - CZAW Built - Rotax 912S
DO NOT ARCHIVE

Last edited by David X on Fri Nov 14, 2008 7:15 pm; edited 1 time in total

notsew_evets(at)frontiern
Guest

Posted: Fri Nov 14, 2008 7:04 pm Post subject: 601XL Wing Flutter

Bill,  isnt 140 a little fast for the 601 ? especiall in rough air..



Also read the CFRs about flying near power stations.....





---

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