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CH601 Yuba City Photos Link (flutter)

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Gus(at)flywithgus.com
Guest

Posted: Thu Apr 24, 2008 7:38 am Post subject: CH601 Yuba City Photos Link (flutter)

Just an FYI. It doesn't have to be high airspeed. Many old timers may 

remember the Ritz Standard Ultralight. Herb Ritz met the end because of 

flutter. NTSB Ritz Flutter 

<http://www.ntsb.gov/ntsb/brief.asp?ev_id 001214X40183&key=1> For 

example my "slow" Cessna 120 has mass balanced ailerons. Factors could 

be amount (weight) of paint, freedom of movement (flex hinge vs. piano), 

additional weight behind hinge line (trim servo), and changing the 

aerodynamic qualities of the surface (trim tab deflection). Not any one 

of these factors necessarily would make a surface flutter but it may be 

a combination of all. Every surface, even a balanced one, has a natural 

frequency which it will flutter. The surface just must be balanced in a 

way that it's frequency will never be encountered within the flight 

envelope.



-Gus

Frank Roskind wrote:

 	  Quote: 	
		   Flutter is an interesting hypothesis, but flutter often occurs at 

 higher true airspeeds, which come from normal indicated airspeeds at 

 high density altitudes.

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Wed Apr 30, 2008 1:45 pm Post subject: Re: CH601 Yuba City Photos Link (flutter)

Gus, I've been thinking about aileron balance. How exactly do you balance one to know that it will not encounter certain frequencies. Is there are procedure for this.



I'm guessing the XLs ailerons are meant to balance each other via the control cables? What if the cables get a slight bitof slack in them?



Also, I'll have a trim tab and servo in my XL in one of the ailerons. Even though the plans don't mention balancing them (that I'm aware of yet) it would probably be a good idea to balance them. That being the case I'm guessing a mod to the outer portion of the aileron and rear spar to allow for a balance weight is in order. Even so, that will only get me static balance, how about dynamic balance?



 	  Gus(at)flywithgus.com wrote: 	
		  Just an FYI. It doesn't have to be high airspeed. Many old timers may 

remember the Ritz Standard Ultralight. Herb Ritz met the end because of 

flutter. NTSB Ritz Flutter 

<http> For 

example my "slow" Cessna 120 has mass balanced ailerons. Factors could 

be amount (weight) of paint, freedom of movement (flex hinge vs. piano), 

additional weight behind hinge line (trim servo), and changing the 

aerodynamic qualities of the surface (trim tab deflection). Not any one 

of these factors necessarily would make a surface flutter but it may be 

a combination of all. Every surface, even a balanced one, has a natural 

frequency which it will flutter. The surface just must be balanced in a 

way that it's frequency will never be encountered within the flight 

envelope.



-Gus

Frank Roskind wrote:

 	  Quote: 	
		   Flutter is an interesting hypothesis, but flutter often occurs at 

 higher true airspeeds, which come from normal indicated airspeeds at 

 high density altitudes.

Afterfxllc(at)aol.com
Guest

Posted: Wed Apr 30, 2008 4:55 pm Post subject: CH601 Yuba City Photos Link (flutter)

Andy,

 I am considering adding mass to my ailerons just as you would with a nose  wheel that shimmies. If you add some weight to the trailing edge of the ailerons  it would make flutter at the speeds we fly almost impossible. In the Van's RV  you add mass in the form of a steel pipe inside the ailerons. In the case of a  nose wheel you can add lead inside the wheel pant and the shear mass of the  weight make it harder to shimmy. One thing to note it has been the right  wing that folds first and that is the light aileron so while it doesn't call for  it in the plans I am seriously considering doing it. You can't counter balance  the ailerons on a 601 because you have nowhere for the counter weight to  go.

  

  

 Gus, I've been thinking about aileron balance. How exactly do you balance  one to know that it will not encounter certain frequencies. Is there are  procedure for this.



I'm guessing the XLs ailerons are meant to balance  each other via the control cables? What if the cables get a slight bitof slack  in them?



Also, I'll have a trim tab and servo in my XL in one of the  ailerons. Even though the plans don't mention balancing them (that I'm aware of  yet) it would probably be a good idea to balance them. That being the case I'm  guessing a mod to the outer portion of the aileron and rear spar to allow for a  balance weight is in order. Even so, that will only get me static balance, how  about dynamic balance?

Gus(at)flywithgus.com wrote:

 	  Quote: 	
		   Just an  FYI. It doesn't have to be high airspeed. Many old timers may 

 remember  the Ritz Standard Ultralight. Herb Ritz met the end because of 

 flutter.  NTSB Ritz Flutter 

  For 

 example my "slow" Cessna 120 has  mass balanced ailerons. Factors could 

 be amount (weight) of paint,  freedom of movement (flex hinge vs. piano), 

 additional weight behind  hinge line (trim servo), and changing the 

 aerodynamic qualities of the  surface (trim tab deflection). Not any one 

 of these factors necessarily  would make a surface flutter but it may be 

 a combination of all. Every  surface, even a balanced one, has a natural 

 frequency which it will  flutter. The surface just must be balanced in a 

 way that it's frequency  will never be encountered within the flight 

 envelope.

 

  -Gus


	




 

  



Need a new ride? Check out the largest site for U.S. used car listings at AOL Autos.

  [quote][b]

notsew_evets(at)frontiern
Guest

Posted: Wed Apr 30, 2008 6:42 pm Post subject: CH601 Yuba City Photos Link (flutter)

TRAILING EDGE ?

  

 Oh brother.....

 [quote]   ---

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Thu May 01, 2008 3:38 am Post subject: Re: CH601 Yuba City Photos Link (flutter)

The more I ponder this, the more it souunds like this is the problem. Probably nothing at all wrong with the wing, until it starts shaking like hell from aileron flutter.



Actually, I've been thinking of a design to counter balance the ailerons. Certainly seems doable, would look good, and wouldn't cause take away from the structural integrity of the wing. It's doable, I'm just wondering what all the proper procedures are for actually correctly statically and dynamically balancing an aileron is. Do you have any info on that?



[quote="Afterfxllc(at)aol.com"]Andy,

 I am considering adding mass to my ailerons just as you would with a nose  wheel that shimmies. If you add some weight to the trailing edge of the ailerons  it would make flutter at the speeds we fly almost impossible. In the Van's RV  you add mass in the form of a steel pipe inside the ailerons. In the case of a  nose wheel you can add lead inside the wheel pant and the shear mass of the  weight make it harder to shimmy. One thing to note it has been the right  wing that folds first and that is the light aileron so while it doesn't call for  it in the plans I am seriously considering doing it. You can't counter balance  the ailerons on a 601 because you have nowhere for the counter weight to  go.

  

  

 Gus, I've been thinking about aileron balance. How exactly do you balance  one to know that it will not encounter certain frequencies. Is there are  procedure for this.



I'm guessing the XLs ailerons are meant to balance  each other via the control cables? What if the cables get a slight bitof slack  in them?



Also, I'll have a trim tab and servo in my XL in one of the  ailerons. Even though the plans don't mention balancing them (that I'm aware of  yet) it would probably be a good idea to balance them. That being the case I'm  guessing a mod to the outer portion of the aileron and rear spar to allow for a  balance weight is in order. Even so, that will only get me static balance, how  about dynamic balance?

Gus(at)flywithgus.com wrote:

 	  Quote: 	
		   Just an  FYI. It doesn't have to be high airspeed. Many old timers may 

 remember  the Ritz Standard Ultralight. Herb Ritz met the end because of 

 flutter.  NTSB Ritz Flutter 

  For 

 example my "slow" Cessna 120 has  mass balanced ailerons. Factors could 

 be amount (weight) of paint,  freedom of movement (flex hinge vs. piano), 

 additional weight behind  hinge line (trim servo), and changing the 

 aerodynamic qualities of the  surface (trim tab deflection). Not any one 

 of these factors necessarily  would make a surface flutter but it may be 

 a combination of all. Every  surface, even a balanced one, has a natural 

 frequency which it will  flutter. The surface just must be balanced in a 

 way that it's frequency  will never be encountered within the flight 

 envelope.

 

  -Gus



	




 

  



Need a new ride? Check out the largest site for U.S. used car listings at AOL Autos.

   	  Quote: 	
		  [b]

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Thu May 01, 2008 3:55 am Post subject: Re: CH601 Yuba City Photos Link (flutter)

I'd say the proper way to do it would be to balance from the front, but in theory it also makes sense. More momentum to have to overcome on each cycle to to get moving in the first place. Kind of like a longer pendulum on a clock, it moves slower. Still I think the overriding effect would be that of connecting a utility trailer to your car and then proceeding to put all the weight in the back of the trailer, that sucker will be all over the street. Certainly the more weight you put back there the lower the frequency would be, but it's not a good way to trailer stuff.

[quote="notsew_evets(at)frontiern"]TRAILING EDGE ?

  

 Oh brother.....

  	  Quote: 	
		     ---

steveadams

Joined: 10 Jan 2006
Posts: 191

Posted: Thu May 01, 2008 4:32 am Post subject: Re: CH601 Yuba City Photos Link (flutter)

I'm not going to get into the speculation bandwagon, because I think many of the speculators don't know what they are talking about, but I have one comment. If you are really concerned about aileron flutter, probably the surest fix would be to build the non-hinged ailerons. I know it's too simple and not as exciting and fun as making up ways to mass balance the ailerons, but increasing stiffness and decreasing slop in the system is the best way to ensure the ailerons won't flutter within the xl flight envelope.

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Thu May 01, 2008 5:54 am Post subject: Re: CH601 Yuba City Photos Link (flutter)

Too late. I already made the hinged ailerons. I just like that design better. I agree, the stiffness of the skins would act as a damper though.



 	  steveadams wrote: 	
		  I'm not going to get into the speculation bandwagon, because I think many of the speculators don't know what they are talking about, but I have one comment. If you are really concerned about aileron flutter, probably the surest fix would be to build the non-hinged ailerons. I know it's too simple and not as exciting and fun as making up ways to mass balance the ailerons, but increasing stiffness and decreasing slop in the system is the best way to ensure the ailerons won't flutter within the xl flight envelope.

planecrazydld(at)yahoo.co
Guest

Posted: Thu May 01, 2008 1:43 pm Post subject: CH601 Yuba City Photos Link (flutter)

Gentlemen;



Aileron balance cables do not provide mas or aerodynamic balance - they simply complete the mechanical actuation circuit - hence balance.



Aerodynamic balance involves active aerodynamic surfaces of the control surface that are place ahead of the effective hinge line.



Mass balance refers to mass added forward of the effective hinge line to result in a painted, ready to fly, surface static balance (pivoting on the actual hinge) with the leading edge about 10° down.



Afterfxllc(at)aol.com wrote:[quote]      Andy,

 I am considering adding mass to my ailerons just as you would with a nose  wheel that shimmies. If you add some weight to the trailing edge of the ailerons  it would make flutter at the speeds we fly almost impossible. In the Van's RV  you add mass in the form of a steel pipe inside the ailerons. In the case of a  nose wheel you can add lead inside the wheel pant and the shear mass of the  weight make it harder to shimmy. One thing to note it has been the right  wing that folds first and that is the light aileron so while it doesn't call for  it in the plans I am seriously considering doing it. You can't counter balance  the ailerons on a 601 because you have nowhere for the counter weight to  go.

  

  

 Gus, I've been thinking about aileron balance. How exactly do you balance  one to know that it will not encounter certain frequencies. Is there are  procedure for this.



I'm guessing the XLs ailerons are meant to balance  each other via the control cables? What if the cables get a slight bitof slack  in them?



Also, I'll have a trim tab and servo in my XL in one of the  ailerons. Even though the plans don't mention balancing them (that I'm aware of  yet) it would probably be a good idea to balance them. That being the case I'm  guessing a mod to the outer portion of the aileron and rear spar to allow for a  balance weight is in order. Even so, that will only get me static balance, how  about dynamic balance?

Gus(at)flywithgus.com wrote:

 	  Quote: 	
		   Just an  FYI. It doesn't have to be high airspeed. Many old timers may 

  remember  the Ritz Standard Ultralight. Herb Ritz met the end because of 

 flutter.  NTSB Ritz Flutter 

  For 

 example my "slow" Cessna 120 has  mass balanced ailerons. Factors could 

 be amount (weight) of paint,  freedom of movement (flex hinge vs. piano), 

 additional weight behind  hinge line (trim servo), and changing the 

 aerodynamic qualities of the  surface (trim tab deflection). Not any one 

 of these factors necessarily  would make a surface flutter but it may be 

 a combination of all. Every  surface, even a balanced one, has a natural 

 frequency which it will  flutter. The surface just must be balanced in a 

 way that it's frequency  will never be encountered within the flight 

 envelope.

 

  -Gus


	




 

  

Dave Downey

  Harleysville (SE) PA

  100 HP Corvair

         Be a better friend, newshound, and  [quote][b]

planecrazydld(at)yahoo.co
Guest

Posted: Thu May 01, 2008 1:48 pm Post subject: CH601 Yuba City Photos Link (flutter)

stiffer usually does mean a different natural frequency. Maybe there is some merit in that argument. However, haven't both forms failed for whatever reason?



steveadams <dr_steve_adams(at)yahoo.com> wrote:[quote] --> Zenith-List message posted by: "steveadams" 



I'm not going to get into the speculation bandwagon, because I think many of the speculators don't know what they are talking about, but I have one comment. If you are really concerned about aileron flutter, probably the surest fix would be to build the non-hinged ailerons. I know it's too simple and not as exciting and fun as making up ways to mass balance the ailerons, but increasing stiffness and decreasing slop in the system is the best way to ensure the ailerons won't flutter within the xl flight envelope.





Read this topic online          Be a better friend, newshound, and  [quote][b]

purplemoon99(at)bellsouth
Guest

Posted: Thu May 01, 2008 1:50 pm Post subject: CH601 Yuba City Photos Link (flutter)

Do you know if all the planes  that have had the folding problem had hinge 

or hingeless ailerons, or is it a  mix ? Joe N101HD 601XL?RAM

---

planes_by_ken(at)bellsout
Guest

Posted: Thu May 01, 2008 5:31 pm Post subject: CH601 Yuba City Photos Link (flutter)

FWIW:

 OK, this one I am really sure about!  THE FURTHER AFT THE BALANCE POINT OF THE SURFACE THE MORE LIKELY FLUTTER BECOMES!  Please, Do NOT add weight to the trailing edge!

 I have checked the surface balance on many A/C.  They need to be checked after repair or any paint job. (you might be surprised about how many planes come back from the paint shop and have not had the balance done)  Balance weights are installed forward of the hinge line.  Even on the high wing Cessna ailerons where at first glance it does not look like it is.  The faster that an airplane is designed to fly, the closer the balance range is to the hinge line, also the allowable range becomes smaller.  On some turboprops and larger, the surface is supposed to balance at the hinge line.  On the Beech Bonanza and Baron series the surfaces were originally magnesium.  Magnesium is lighter but much more prone to corrosion than aluminum.  Because of the corrosion problems, they replaced the magnesium with aluminum but did not change the balance.  This lead to the surfaces being tail heavy.  The proper way to paint them is with the leading edge hanging down so the thinest paint is at the trailing edge.  You are only allowed to add so much weight to the balance weight.  If you can not bring the surface to balance it needs to stripped and repainted.  I have never had to move a surface balance point aft, only add weight to move it forward.  Installing an anti-servo tab would add weight to the trailing edge of the elevator.  This would be a show stopper for me.  (assuming adding a second trim tab to the other elevator, modified to work as an anti-servo tab, and without provisions for balancing)  I have thought about moving the trim actuators to the wing and stab, but making the geometry of the linkage work would be difficult, but certainly not impossible.  (cables and fair-leads are used on some Beeches)   Cable tension is VERY important as are no slop linkages.  I understand that loose cables have brought down planes.  I hope the tension values are listed somewhere in the instructions.  Typical values are between 30 and 40 pounds.  Your EAA chapter may own a tensiometer to check this.

 

 On flutter:  From AC 90-89A, AMATEUR-BUILT AIRCRAFT AND ULTRALIGHT FLIGHT TESTING HANDBOOK page 52 and 53

 "f. Flutter can happen at any speed, including take-off speed. At low airspeeds, however, structural and aerodynamic damping quickly suppress the flutter  motion. But as the airspeed increases, so do the aerodynamic driving forces generated by the aileron.  When they are large enough to cancel the damping, the motion becomes continuous. 

 g. Further SMALL INCREASES will produce a divergent, or increasing oscillation, which can quickly exceed the structural limits of the airframe. Even when flutter is on the verge of becoming catastrophic it can still be very hard to detect. What causes this is the high frequency of the oscillation, typically between 5 and 20 Hz (cycles per second). It will take but a small increase in speed (1⁄4 knot or less) to remove what little damping remains and

 the motion will become divergent rapidly." (Italics added)

 The event reported by Bill of GA may have been avibration like skin oil-canning.  If it was a true flutter event increasing the speed would have made it worse.  Increasing the speed may have dampened the vibration or moved him out of the conditions that caused the vibrations.  All vibrations are not flutter, but flutter is a vibration that is resonant, or self exciting: each cycle adds energy, making the vibration worse.  Engines and propellers v

 vibrate.  Sometimes worse at one RPM than others.  If the engine/prop vibrates at a resonant frequency, the crankshaft can break, prop blades and hubs can come apart.

 

 Take this information for what it is worth: I am not a structural or aeronautical engineer or an aerodynamicist.

 

 Complete kit with S/N

 Rudder and horizontal stabilizer 98 % complete.

 Elevator 50%.

 Ken (really slow) Lilja A&P

 

 

     [quote][b]

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Fri May 02, 2008 4:22 am Post subject: Re: CH601 Yuba City Photos Link (flutter)

I've been doing some research on this, apparently mass balance is a good thing, althought done wrong could actually cause flutter too. Do you have any more info on how to do it right? I'm seeing some things like the balance isn't actually outright balanced per se, but only a certain percentage of balance is called for.  Would something like this need to be done in a wind tunnel to get it right?



do not archive



[quote="planecrazydld(at)yahoo.co"]Gentlemen;



Aileron balance cables do not provide mas or aerodynamic balance - they simply complete the mechanical actuation circuit - hence balance.



Aerodynamic balance involves active aerodynamic surfaces of the control surface that are place ahead of the effective hinge line.



Mass balance refers to mass added forward of the effective hinge line to result in a painted, ready to fly, surface static balance (pivoting on the actual hinge) with the leading edge about 10? down.



Afterfxllc(at)aol.com wrote:[quote]      Andy,

 I am considering adding mass to my ailerons just as you would with a nose  wheel that shimmies. If you add some weight to the trailing edge of the ailerons  it would make flutter at the speeds we fly almost impossible. In the Van's RV  you add mass in the form of a steel pipe inside the ailerons. In the case of a  nose wheel you can add lead inside the wheel pant and the shear mass of the  weight make it harder to shimmy. One thing to note it has been the right  wing that folds first and that is the light aileron so while it doesn't call for  it in the plans I am seriously considering doing it. You can't counter balance  the ailerons on a 601 because you have nowhere for the counter weight to  go.

  

  

 Gus, I've been thinking about aileron balance. How exactly do you balance  one to know that it will not encounter certain frequencies. Is there are  procedure for this.



I'm guessing the XLs ailerons are meant to balance  each other via the control cables? What if the cables get a slight bitof slack  in them?



Also, I'll have a trim tab and servo in my XL in one of the  ailerons. Even though the plans don't mention balancing them (that I'm aware of  yet) it would probably be a good idea to balance them. That being the case I'm  guessing a mod to the outer portion of the aileron and rear spar to allow for a  balance weight is in order. Even so, that will only get me static balance, how  about dynamic balance?

Gus(at)flywithgus.com wrote:

 	  Quote: 	
		   Just an  FYI. It doesn't have to be high airspeed. Many old timers may 

  remember  the Ritz Standard Ultralight. Herb Ritz met the end because of 

 flutter.  NTSB Ritz Flutter 

  For 

 example my "slow" Cessna 120 has  mass balanced ailerons. Factors could 

 be amount (weight) of paint,  freedom of movement (flex hinge vs. piano), 

 additional weight behind  hinge line (trim servo), and changing the 

 aerodynamic qualities of the  surface (trim tab deflection). Not any one 

 of these factors necessarily  would make a surface flutter but it may be 

 a combination of all. Every  surface, even a balanced one, has a natural 

 frequency which it will  flutter. The surface just must be balanced in a 

 way that it's frequency  will never be encountered within the flight 

 envelope.

 

  -Gus



	




 

  

Dave Downey

  Harleysville (SE) PA

  100 HP Corvair

         Be a better friend, newshound, and   	  Quote: 	
		  [b]

amyvega2005(at)earthlink.
Guest

Posted: Fri May 02, 2008 5:36 am Post subject: CH601 Yuba City Photos Link (flutter)

All,

Though I think this entire stream is pure speculation and monday moring quarterbacking,  FLutter and airleron balance has been covered in previous articles in the Zenith quarterly Magazine.  There are plans and schematics to place balance rods on ailerons. Stick to the plans!  If yu tension the cable correctly there should be no issue with flutter.  

The stream where the guy wanted to "alance the ailerons due to a servo in the left is simply,  way off the mark.   BUild it to plans, tension the cables to plans,  Fly it "within its parameters".   



Juan



--

PatrickW

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

Posted: Fri May 02, 2008 8:57 am Post subject: Re: CH601 Yuba City Photos Link (flutter)

 	  amyvega2005(at)earthlink. wrote: 	
		  Stick to the plans! 	




I wonder if any of the accident aircraft had deviations from the plans...?



It would be nice to know one way or another.



Patrick

XL/Corvair

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Mon May 05, 2008 2:42 pm Post subject: Re: CH601 Yuba City Photos Link (flutter)

Please provide links to Zenith Quarterly. THe plans show nothing on control surface balancing. I'm extremely interested in this. This sounds exactly like what's going on. I wouldn't say this is monday morning quarterbacking at all. This is an age old problem, and one that's probably being overlooked by the new throngs of people to sport aviation. Personally, I think this is in fact what the problem is. Thanks Gus!



 	  amyvega2005(at)earthlink. wrote: 	
		  All,

Though I think this entire stream is pure speculation and monday moring quarterbacking,  FLutter and airleron balance has been covered in previous articles in the Zenith quarterly Magazine.  There are plans and schematics to place balance rods on ailerons. Stick to the plans!  If yu tension the cable correctly there should be no issue with flutter.  

The stream where the guy wanted to "alance the ailerons due to a servo in the left is simply,  way off the mark.   BUild it to plans, tension the cables to plans,  Fly it "within its parameters".   



Juan



--

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