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Juan Vega Jr

Joined: 13 Jan 2009
Posts: 157

Posted: Mon Jun 01, 2009 5:43 pm Post subject: Putting Flutter Issue to Bed

See Below. Lets Quit the BS, as the test result show the Flutter is the wrong tree to bark up. Lets look a the quality of the builds, even the AMD one or the lack Pilot control.

This reprot makes it clear Flutter aint happening!  Now someone needs to take this to the press to make sure the bad press we recieved gets its proper rebuttal.



Juan Vega



ARTICLE from Zenith Europe-

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 oft suggested flutter is an exceedingly unlikely â€œsmoking gunâ€ 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 anyoneâ€™s mind: â€œNo tendency to flutter or divergence was found within the flight envelope of the CH 601 XLâ€. 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 â€œreal worldâ€); 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 Zenairâ€™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 aircraftâ€™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. â€œThe 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 envelopeâ€ said Chris Heintz, who also attended the meetings.

jmaynard

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

Posted: Mon Jun 01, 2009 6:22 pm Post subject: Putting Flutter Issue to Bed

On Mon, Jun 01, 2009 at 09:40:39PM -0400, Juan Vega wrote:

 	  Quote: 	
		   See Below. Lets Quit the BS, as the test result show the Flutter is the

 wrong tree to bark up. Lets look a the quality of the builds, even the AMD

 one or the lack Pilot control.


	


Just because flutter isn't the issue (I agree with that) doesn't mean that

there's not some other problem with the aircraft itself. We just don't know.



Of course, you're invulnerable, so you'll never have a problem.



Come on, Juan, pull your head out of the sand.

-- 

Jay Maynard, K5ZC, PP-ASEL, CFI-SP   http://www.conmicro.com

http://jmaynard.livejournal.com       http://www.tronguy.net

Fairmont, MN (KFRM)                        (Yes, that's me!)

AMD Zodiac CH601XLi N55ZC http://www.tronguy.net/N55ZC.shtml

_________________
Jay Maynard, K5ZC
AMD Zodiac XLi N55ZC

psm(at)att.net
Guest

Posted: Mon Jun 01, 2009 6:36 pm Post subject: Putting Flutter Issue to Bed

Indeed, the NTSB identified another problem - one which I think might 

explain all the accidents.  It is the stick gradient problem that 

makes it easier to pull additional G's as you pull additional G's.



The NTSB demanded both this be fixed and aileron mass balancing be 

added.  I hope the Zenair folks are going to release design changes 

to resolve those issues.  It really doesn't matter whether the 

changes are justified by German engineers or not.  The changes are 

still needed to satisfy the NTSB demands.



Paul

XL grounded

do not archive



At 07:21 PM 6/1/2009, you wrote:



 	  Quote: 	
		  Just because flutter isn't the issue (I agree with that) doesn't mean that

there's not some other problem with the aircraft itself. We just don't know.

d.goddard(at)ns.sympatico
Guest

Posted: Tue Jun 02, 2009 1:44 am Post subject: Putting Flutter Issue to Bed

I don't know Paul. With the engineering report in hand the NTSB may withdraw 

it's request for mass balancing, it's likely to go unfulfilled at this 

point.  The stick issue is an undesirable feature but training could/should 

address it. My hope is that the aircraft just experienced a very bad patch 

of incidents and that history will not repeat itself. A new stick 

arrangement would be nice, many of the Zenith designs seem to require much 

more force in roll than pitch.



---

psm(at)att.net
Guest

Posted: Tue Jun 02, 2009 2:13 am Post subject: Putting Flutter Issue to Bed

Hi Dave,



While you may be correct about the NTSB changing their position on 

the design changes, I seriously doubt that will happen.



I don't think they made the demand for aileron balance based on 

research about the Zodiac design.  I think it was made based on the 

experience in the industry that aileron balance makes safer 

airplanes.  According to a number of people I have contacted in this 

regard, industry standard handling of this question has shown aileron 

mass balancing is beneficial (i.e. saves lives) on all airplane 

designs except for those that have fabric covered ailerons.   Please 

keep in mind that there have been a relatively high number of 

structural failures on Zodiac XLs.  That is why the NTSB was looking 

at this particular design in the first place.



I don't know why you made the comment about the difference in forces 

for aileron vs. elevator travel.  That is not an issue for me or the 

NTSB.  The issue is the clear flaw that as you increase the G's being 

pulled by the plane it becomes easier to add more G's.  While 

training about this flaw might prevent some deaths it seems more 

appropriate to actually fix the design.  I don't know exactly what 

this will take, but my sense is that it is not difficult to fix.  I 

don't believe any pilot would apply too much force to the stick on 

purpose.  I think this is possible in a panic situation or possibly 

as a weird mistake where the passenger accidently kicks the stick or 

some such thing.



If the NTSB issues another letter saying they have decided to 

withdraw their statement that these changes are needed then I will 

consider dropping the same needs from my decision to ground my 

plane.  As it now stands, I need approved engineering changes from 

Zenith or a related source for these issues before my plane gets 

un-grounded.  The longer it takes for Zenith to decide to create 

those engineering changes the longer my plane will be grounded.



Paul

XL Grounded

At 02:41 AM 6/2/2009, you wrote:



 	  Quote: 	
		  I don't know Paul. With the engineering report in hand the NTSB may 

withdraw it's request for mass balancing, it's likely to go 

unfulfilled at this point.  The stick issue is an undesirable 

feature but training could/should address it. My hope is that the 

aircraft just experienced a very bad patch of incidents and that 

history will not repeat itself. A new stick arrangement would be 

nice, many of the Zenith designs seem to require much more force in 

roll than pitch.

Thruster87

Joined: 16 Apr 2008
Posts: 193
Location: Australia

Posted: Tue Jun 02, 2009 2:36 am Post subject: Re: Putting Flutter Issue to Bed

 	  psm(at)att.net wrote: 	
		  Hi Dave,



While you may be correct about the NTSB changing their position on 

the design changes, I seriously doubt that will happen.



I don't think they made the demand for aileron balance based on 

research about the Zodiac design.  I think it was made based on the 

experience in the industry that aileron balance makes safer 

airplanes.  According to a number of people I have contacted in this 

regard, i[b]ndustry standard handling of this question has shown aileron 

mass balancing is beneficial (i.e. saves lives) on all airplane 

designs except for those that have fabric covered ailerons.[/b]   Please 

keep in mind that there have been a relatively high number of 

structural failures on Zodiac XLs.  That is why the NTSB was looking 

at this particular design in the first place.



I don't know why you made the comment about the difference in forces 

for aileron vs. elevator travel.  That is not an issue for me or the 

NTSB.  The issue is the clear flaw that as you increase the G's being 

pulled by the plane it becomes easier to add more G's.  While 

training about this flaw might prevent some deaths it seems more 

appropriate to actually fix the design.  I don't know exactly what 

this will take, but my sense is that it is not difficult to fix.  I 

don't believe any pilot would apply too much force to the stick on 

purpose.  I think this is possible in a panic situation or possibly 

as a weird mistake where the passenger accidently kicks the stick or 

some such thing.



If the NTSB issues another letter saying they have decided to 

withdraw their statement that these changes are needed then I will 

consider dropping the same needs from my decision to ground my 

plane.  As it now stands, I need approved engineering changes from 

Zenith or a related source for these issues before my plane gets 

un-grounded.  The longer it takes for Zenith to decide to create 

those engineering changes the longer my plane will be grounded.



Paul

XL Grounded



I just balanced the ailerons and the elevators for a DC4 which are fabric and there are many other aircraft with mass balanced fabric covered ailerons. Cheers 



	
[/quote]

d.goddard(at)ns.sympatico
Guest

Posted: Tue Jun 02, 2009 2:50 am Post subject: Putting Flutter Issue to Bed

The comment was actually in response to the stick gradient concern. It had 

stuck in my mind from reading your email and my response was off target I 

guess. I have thought that the stiff roll and very easy pitch was a sort of 

odd arrangement, but maybe that's just something to get used to. I admire 

your resolve in this matter, do you know if there are any certified light 

aircraft designs with metal ailerons that do not use mass balance? I 

understand that it is common practice, but surely CH is not the first to 

break with tradition. My feeling is that while it is common, I would be 

unlikely to want to add any structure that does not actually need to be 

present.



---

psm(at)att.net
Guest

Posted: Tue Jun 02, 2009 3:25 am Post subject: Putting Flutter Issue to Bed

Hi Dave,



I don't have universal knowledge of what light aircraft designs 

exist.  I do know from personal experience that it is extremely 

common, perhaps almost universal, that airplane designs call for 

different control pressure and movement in different axes.  While 

this seems to be a criteria that some aviation magazine authors think 

is important (i.e, "Control Harmony") I have not heard anyone suggest 

there was a safety issue here.



In general, I agree with you completely that it is a bad idea to add 

unnecessary features to a light plane design.  If nothing else the 

added weight and expense are things to avoid.



It is the question of how you define what is necessary and what is 

not that makes this problem so perplexing.  For me, the NTSB saying 

the changes are necessary is enough.  For others it is not.



I make no claim that I am right and other builders are wrong.  This 

is a very difficult problem to resolve, and those who believe there 

is no need to fix anything have a lot of facts to support their 

decision.  Indeed this is not a democratic situation.  We don't need 

to agree or come to a consensus decision.



Building, and particularly flying, experimental airplanes is, and 

will always be, a dangerous activity.  Each builder and owner must 

decide for himself just how much risk is acceptable.  This applies 

just as much for risks that are well known as for ones that are 

subject to question.



My own decision was made based on my own criteria and my own 

situation.  I searched my soul and discussed the situation with my 

wife (who also flies) and reached the conclusion I would ground my 

plane, as suggested by the NTSB, until the two mentioned changes were 

implemented.  If I am demonstrating resolve, it is merely that there 

have been no changes in the situation that would convince me I should 

change my own decision.



Best regards,



Paul

XL grounded

At 03:49 AM 6/2/2009, you wrote:

 	  Quote: 	
		  The comment was actually in response to the stick gradient concern. 

It had stuck in my mind from reading your email and my response was 

off target I guess. I have thought that the stiff roll and very easy 

pitch was a sort of odd arrangement, but maybe that's just something 

to get used to. I admire your resolve in this matter, do you know if 

there are any certified light aircraft designs with metal ailerons 

that do not use mass balance? I understand that it is common 

practice, but surely CH is not the first to break with tradition. My 

feeling is that while it is common, I would be unlikely to want to 

add any structure that does not actually need to be present.

tonyplane(at)bellsouth.ne
Guest

Posted: Tue Jun 02, 2009 6:16 am Post subject: Putting Flutter Issue to Bed

"Indeed, the NTSB identified another problem - one which I think might

 	  Quote: 	
		   explain all the accidents.  It is the stick gradient problem that makes it

 easier to pull additional G's as you pull additional G's.



 The NTSB demanded both this be fixed and aileron mass balancing be

added."
	




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



Maybe I missed it (see attached extracts below from the NTSB Report) but I 

do not see

where the NTSB demanded the light stick forces on the XL (also found on many

other aircraft) be "fixed", nor demanded balancing of the ailerons.



I personally believe that some if not all of the structural failures were

caused improper use of the stick, also know to be a wing removal device on

most aircraft.



Tony Graziano



XL; Jab; N493TG  495  really enjoyable hours.

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



Recommendations extracted from the NTSB Report



Require a comprehensive evaluation of the wing and aileron system on the 

Zodiac CH-601XL, including ground vibration tests, to identify design and/or 

operational changes that will reduce the potential for flutter; the 

evaluation should give significant consideration to the benefits of 

installing mass-balanced ailerons and should also address the adequacy of 

cable tension values specified by Zenair.



Evaluate the stick-force gradient of the Zodiac CH-601XL at the maximum aft 

center of gravity and notify pilots of the stick-force gradient that occurs 

at the aft center of gravity, especially at the higher G forces.

Potential Role of Stick Forces  (Extracted from the NTSB Report)

In an effort to identify potential factors that might have contributed to

the many in-flight breakups of CH-601XL airplanes, and mindful of the fact

that high loads can cause structural failure, the Safety Board examined the

control stick forces required to generate high maneuver loads19 on the

accident airplane model. Zenair provided the Safety Board with a flight test

report that had been used to validate the airplane design under ASTM

standards. The report included data on the stick forces required to generate

maneuver loads or Gs.20 The term "stick force per G" refers to the control

force gradient that is derived from flight test data. Data from the

Comparative Aircraft Flight Efficiency Foundation's21 airplane performance

reports show that the stick force per G on other airplanes is similar to

that of the Zodiac CH-601XL except that, on



the CH-601XL, the stick-force gradient lessens distinctly as loads increase

above 2.5 Gs.22 The lessening of the gradient continues as loads surpass 4

Gs. As a result, at high Gs, a moderate increase in stick force could result

in a larger than expected increase in maneuver loads. A sufficient

stick-force gradient is required for pilots to maneuver an airplane safely.

The Safety Board recognizes that experimental and light sport airplanes

typically exhibit lighter stick forces than airplanes certified under 14 CFR

Part 23 and that, if properly trained, pilots can safely maneuver airplanes

with relatively shallow gradients. However, even experienced pilots may find

control difficult if the gradient is not constant but instead lessens as Gs

increase. With a lessening stick-force gradient, it becomes easier to

inadvertently overcontrol the airplane and reach higher acceleration forces

than intended. Zenair has expressed concern that pilots may be

overcontrolling the airplane with large or aggressive stick movements. On

May 10, 2007, the designer wrote the owners and pilots of Zodiac airplanes

an advisory letter, which included the following: The Zodiac aircraft has a

large amount of elevator control. ... Pushing the stick rapidly full forward

at cruise speed-even briefly-can result in serious damage to the airframe.

Caution must be exercised to not inadvertently push the stick rapidly to its

limits (i.e. while stretching, reaching into the rear baggage compartment,

etc.). In July 2007, the designer issued the following update: Owners should

take note that the CH-601XL has relatively light pitch control forces and

that it is possible to exceed the positive (+6) and the negative (-3)

ultimate load factors if forcing the controls in a very rough or sudden

manner. Pilots usually become familiar with the maneuvering characteristics

of an airplane while operating routinely between the 1 G and 1.5 Gs common

during normal flight. Higher G forces are often disconcerting, and a

lessening of the stick-force gradient may go unnoticed. In addition, the

stick forces are least when operating at the maximum aft center of gravity.

Although the Zodiac designer has advised pilots of the light stick forces,

the Safety Board concludes that pilots may not be aware of the change in the

effect of stick forces that occurs while maneuvering at higher Gs.

Therefore, the Safety Board believes that the FAA should evaluate the

stick-force gradient of the CH-601XL at the maximum aft center of gravity

and notify pilots of the stick-force gradient that occurs at the aft center

of gravity, especially at the higher G forces. In addition, the Safety Board

believes that the FAA should work with ASTM International to develop

requirements to be included in the standards for light sport airplanes that

provide for stick-force characteristics that will minimize the possibility

of pilots inadvertently overcontrolling the airplane.



22 The Zodiac designer also provided flight test data for the CH-600/601

(non-XL) airplanes. The data show that the stick forces are generally

somewhat lighter than those experienced on the CH-601XL but that the

gradients are constant until the airplane reaches at least 4 Gs.

ggower_99(at)yahoo.com
Guest

Posted: Tue Jun 02, 2009 6:54 am Post subject: Putting Flutter Issue to Bed

Hello Paul,

  

 Good explanation...

 If I will ask my wife if I should be flying or not...  I for sure will also be grounded.

  

 Saludos

 Gary Gower

 Flying from Chapala, Mexico.

 701 912S  240 hrs

 building 601 XL  Jab 3300

 Macho Flyer,  Wife grounded 

Do not archive.

--- On Tue, 6/2/09, Paul Mulwitz <psm(at)att.net> wrote:



  	  Quote: 	
		  

 --> Zenith-List message posted by: Paul Mulwitz <psm(at)att.net (psm(at)att.net)>



Hi Dave,

My own decision was made based on my own criteria and my own situation.  I searched my soul and discussed the situation with my wife (who also flies) and reached the conclusion I would ground my plane, as suggested by the NTSB, until the two mentioned changes were implemented.  If I am demonstrating resolve, it is merely that there have been no changes in the situation that would convince me I should change my own decision.



Best regards,



Paul

XL grounded

	


         [quote][b]

Gig Giacona

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

Posted: Tue Jun 02, 2009 8:32 am Post subject: Re: Putting Flutter Issue to Bed

 	  Quote: 	
		  Recommendations extracted from the NTSB Report



Require a comprehensive evaluation of the wing and aileron system on the 

Zodiac CH-601XL, including ground vibration tests, to identify design and/or 

operational changes that will reduce the potential for flutter; the 

evaluation should give significant consideration to the benefits of 

installing mass-balanced ailerons and should also address the adequacy of 

cable tension values specified by Zenair.



	




Recommendation met by GVT report.



 	  Quote: 	
		  

Evaluate the stick-force gradient of the Zodiac CH-601XL at the maximum aft 

center of gravity and notify pilots of the stick-force gradient that occurs 

at the aft center of gravity, especially at the higher G forces.



	




Issue already addressed before it was recommended. We were advised to add an elevator stop quite some time ago. I added mine the weekend after it was recommended. Took about 20-30 minutes. Any additional issue can easily be handled with training. I'd like to see Zenith along with the FAA come out with a requirement much as was done with SFAR 74. This had a major impact with the insurance companies that were insuring Robinson helicopters. In something like a 601 specialized training would reduce accidents to as close to zero as could be hoped and would have the long term effect of making up for, statistically, the accidents we have already had. Not to mention it would be a plus for those CFI-LS out there that choose to use 601XLs.

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

Juan Vega Jr

Joined: 13 Jan 2009
Posts: 157

Posted: Tue Jun 02, 2009 12:10 pm Post subject: Putting Flutter Issue to Bed

Paul,

you need to sell yuor plane, obviously you will not be happy until you are flying a Cessna.

Juan



--

jmaynard

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

Posted: Tue Jun 02, 2009 12:53 pm Post subject: Putting Flutter Issue to Bed

On Tue, Jun 02, 2009 at 04:03:58PM -0400, Juan Vega wrote:

 	  Quote: 	
		   you need to sell yuor plane, obviously you will not be happy until you are

 flying a Cessna.


	


Horse exhaust and hogwash. Just because a plane is an experimental (or SLSA)

does not mean that it cannot adhere to generally accepted standards of safe

aircraft design, or that it gets a free pass for failing to do so. Would you

argue that a pilot of an experimental aircraft need not be trained to the

same standards as a pilot of a 172? It's the identical case.

-- 

Jay Maynard, K5ZC, PP-ASEL, CFI-SP   http://www.conmicro.com

http://jmaynard.livejournal.com       http://www.tronguy.net

Fairmont, MN (KFRM)                        (Yes, that's me!)

AMD Zodiac CH601XLi N55ZC http://www.tronguy.net/N55ZC.shtml

_________________
Jay Maynard, K5ZC
AMD Zodiac XLi N55ZC

tonyplane(at)bellsouth.ne
Guest

Posted: Tue Jun 02, 2009 12:55 pm Post subject: Putting Flutter Issue to Bed

Gig,



Although I do not believe anyone would criticize specialized training in the 

XL (or for that matter any airplane you have not flown before). I find that 

the XL is pretty easy to fly and is forgiving.  I had never really flown the 

XL before I flew my XL's first flight.(had a short ride at the controls at 

the Zenith factory, but was not permitted to stall or land it).



I do not believe that the XL has a reputation for stall/spin type accidents 

common to many other airplanes; in fact, during my Phase I and sometimes 

when I do "air-work", I have purposefully tried cross controlling in various 

flight regimes ( SLOW descending turns etc) and never have had the airplane 

roll off into a departure. I have had it in stall buffet conditions and have 

tried to get it to depart left or right also without success.  I believe I 

could get the airplane to depart, but I would have to really be highly 

uncoordinated, or really stomp the rudder full during the stall and hold it 

until probable departure.(have not tried this and do not plan to - unless 

someone other than me wants to do a complete spin evaluation : ).



I believe that what everyone should be aware of is that you can easily 

induce large elevator deflections with out trying hard - not a problem, 

except at high speeds.



I really like the stick forces in pitch and wish the aileron were was a 

little more "sensitive", but the ailerons also require little stick movement 

(with more force) to start rolling/turning. I have no problems trimming in 

roll or pitch.



Tony Graziano

XL/Jab; N493TG; 496 hrs/1098 landings in my XL.



---

Gig Giacona

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

Posted: Tue Jun 02, 2009 1:00 pm Post subject: Re: Putting Flutter Issue to Bed

 	  jmaynard wrote: 	
		  On Tue, Jun 02, 2009 at 04:03:58PM -0400, Juan Vega wrote:

 	  Quote: 	
		   you need to sell yuor plane, obviously you will not be happy until you are

 flying a Cessna.



	


Horse exhaust and hogwash. Just because a plane is an experimental (or SLSA)

does not mean that it cannot adhere to generally accepted standards of safe

aircraft design, or that it gets a free pass for failing to do so. Would you

argue that a pilot of an experimental aircraft need not be trained to the

same standards as a pilot of a 172? It's the identical case.

-- 

	




Jay



I don't think that is point Juan was trying to make. I think the point is that there is no reasonable act that Zenith could take that would make the person he replied to happy with they aircraft. The problem being this particular poster thinks that anything the NTSB says is golden and he is also under the misconception that the NTSB has the power to demand anything.



And just for the record the pilot of a 601XL doesn't have to be trained to the same level as the pilot of a 172.

_________________
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 Jun 02, 2009 1:16 pm Post subject: Putting Flutter Issue to Bed

On Tue, Jun 02, 2009 at 02:00:35PM -0700, Gig Giacona wrote:

 	  Quote: 	
		   I don't think that is point Juan was trying to make. I think the point is

 that there is no reasonable act that Zenith could take that would make the

 person he replied to happy with they aircraft. The problem being this

 particular poster thinks that anything the NTSB says is golden and he is

 also under the misconception that the NTSB has the power to demand

 anything.


	


I disagree. Zenith could come up with a balance weight kit for hte US, or

just make the one they developed for the UK avalable here, and find a fix

for the G force gradient issue, and I think Paul would be happy,



 	  Quote: 	
		   And just for the record the pilot of a 601XL doesn't have to be trained to

 the same level as the pilot of a 172.


	


The differences have to do with the limited privileges of a sport pilot; the

standards for those elements that are in common are identical.



Perhaps I should have said "Skycatcher" rather than 172. After all, that's a

Cessna. In any event, the idea that sport pilots are less well trained than

private pilots needs to be shot down in flames whenever it comes up. There's

no reason in the word a sport pilot should be any less well trained than a

private pilot. (This was a hot button issue for my CFI-SP examiner, as it is

for me.)



The sport pilot rule is still controversial in some quarters. Accepting

anything less than the same level of safety in aircraft that is given by

part 23, and anything less than the same standard of training as a private

pilot, can only harm the cause - because it gives the naysayers ammunition.

-- 

Jay Maynard, K5ZC, PP-ASEL, CFI-SP   http://www.conmicro.com

http://jmaynard.livejournal.com       http://www.tronguy.net

Fairmont, MN (KFRM)                        (Yes, that's me!)

AMD Zodiac CH601XLi N55ZC http://www.tronguy.net/N55ZC.shtml

_________________
Jay Maynard, K5ZC
AMD Zodiac XLi N55ZC

Gig Giacona

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

Posted: Tue Jun 02, 2009 1:39 pm Post subject: Re: Putting Flutter Issue to Bed

The issue I was trying to address with added training is the one that the NTSB calls out regarding decreased elevator pressure in the higher G edges of the flight envelope. I have no personal evidence that these exist but I'll take the NTSBs word for it until my plane is flying. I intend to address this during phase 1 testing. I have it scheduled in for hour 28.



 	  tonyplane(at)bellsouth.ne wrote: 	
		  Gig,



Although I do not believe anyone would criticize specialized training in the 

XL (or for that matter any airplane you have not flown before). I find that 

the XL is pretty easy to fly and is forgiving.  I had never really flown the 

XL before I flew my XL's first flight.(had a short ride at the controls at 

the Zenith factory, but was not permitted to stall or land it).



I do not believe that the XL has a reputation for stall/spin type accidents 

common to many other airplanes; in fact, during my Phase I and sometimes 

when I do "air-work", I have purposefully tried cross controlling in various 

flight regimes ( SLOW descending turns etc) and never have had the airplane 

roll off into a departure. I have had it in stall buffet conditions and have 

tried to get it to depart left or right also without success.  I believe I 

could get the airplane to depart, but I would have to really be highly 

uncoordinated, or really stomp the rudder full during the stall and hold it 

until probable departure.(have not tried this and do not plan to - unless 

someone other than me wants to do a complete spin evaluation : ).



I believe that what everyone should be aware of is that you can easily 

induce large elevator deflections with out trying hard - not a problem, 

except at high speeds.



I really like the stick forces in pitch and wish the aileron were was a 

little more "sensitive", but the ailerons also require little stick movement 

(with more force) to start rolling/turning. I have no problems trimming in 

roll or pitch.



Tony Graziano

XL/Jab; N493TG; 496 hrs/1098 landings in my XL.



---

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

Gig Giacona

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

Posted: Tue Jun 02, 2009 1:52 pm Post subject: Re: Putting Flutter Issue to Bed

 	  jmaynard wrote: 	
		  

I disagree. Zenith could come up with a balance weight kit for hte US, or

just make the one they developed for the UK avalable here, and find a fix

for the G force gradient issue, and I think Paul would be happy,



	




Why should there be a weight added? The GVT shows that the system, as designed, works. Putting extra weight out in the wing can only add additional stress on the design and God only knows what that will do.



The G force gradient can be dealt with with training if it exists. You have a flying example can you tell me if the G force gradient does in fact exist? And if so are you capable of flying the plane with that gradient now that you know about it? If the answer to that last one is yes then you have just proved my point about training if you can't you need to ground yourself.



 	  Quote: 	
		   And just for the record the pilot of a 601XL doesn't have to be trained to

 the same level as the pilot of a 172.



	
 	  Quote: 	
		  

The differences have to do with the limited privileges of a sport pilot; the

standards for those elements that are in common are identical.



Perhaps I should have said "Skycatcher" rather than 172. After all, that's a

Cessna. In any event, the idea that sport pilots are less well trained than

private pilots needs to be shot down in flames whenever it comes up. There's

no reason in the word a sport pilot should be any less well trained than a

private pilot. (This was a hot button issue for my CFI-SP examiner, as it is

for me.)



The sport pilot rule is still controversial in some quarters. Accepting

anything less than the same level of safety in aircraft that is given by

part 23, and anything less than the same standard of training as a private

pilot, can only harm the cause - because it gives the naysayers ammunition.

-- 

	




I doubt anyone thought you'd have the same level of safety in S-LSA as you would with part 23 aircraft. Why do you think the the FAA limited the weight to 1320 lbs and only allowed it to be a pilot plus one aircraft. The answer is to keep down the damage on the ground and the body count down in an accident. Otherwise they would let LSA pilots fly 172s with 4 people on board in VFR/Day only.

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

paulrod36(at)msn.com
Guest

Posted: Tue Jun 02, 2009 2:23 pm Post subject: Putting Flutter Issue to Bed

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  Paul--- Has anybody played with the idea of installing two equal strength  coil or flat springs somewhere at the bottom of the control stick, to add  resistance as the stick increases deflection? They might have to be fairly  stiff, but they might deter the heavy-handed or unwary from bankin' and  yankin'.  Just a thought.

  

 Paul R.

 [quote]   ---

psm(at)att.net
Guest

Posted: Tue Jun 02, 2009 2:54 pm Post subject: Putting Flutter Issue to Bed

Hi Paul,



I am an experienced engineer, but my field is electronics rather than 

mechanical or aeronautical design.  I don't know the best way to deal 

with the stick design problem.  I really hope the experts at 

Zenair/Zenith will design and issue an appropriate change.



That said, I will make a comment or two based on things I have heard 

- mostly on this list.



I think adding springs or bungie cords to the stick would make the 

forces heavier, but might not have any impact on the real 

problem.  The real problem seems to be that it gets progressively 

easier to pull G's as you pull more G's.  So, if you are already 

pulling 3 G's a little more pull on the stick might get you to 6 G's 

rather than 3.2.



The change that seems to be a more appropriate fix is to add a dense 

weight to the bottom of the stick.  This would be impacted by pulling 

G's so that the more force on the weight the harder it gets to 

increase the load on the wings.  This would still present the nice 

light stick forces when the plane is lightly loaded with G's but make 

it progressively more difficult to add more load.



Paul

XL Grounded

do not archive

At 03:22 PM 6/2/2009, you wrote:

 	  Quote: 	
		  Paul--- Has anybody played with the idea of installing two equal 

strength coil or flat springs somewhere at the bottom of the control 

stick, to add resistance as the stick increases deflection? They 

might have to be fairly stiff, but they might deter the heavy-handed 

or unwary from bankin' and yankin'.  Just a thought.



Paul R.

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