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smokeysmail(at)bigpond.co
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 Posted: Thu Aug 05, 2010 12:06 am Post subject: Lightning Elevator flutter |
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Has anyone had a problem with elevator flutter? Can anyone tell me the mass balance limits of the lightning control surfaces?
Thanks Smokey
[quote][b]
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info(at)flylightning.net
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| Posted: Thu Aug 05, 2010 5:06 am Post subject: Lightning Elevator flutter |
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No. Did you experience this or just simply asking?
The prototype was mass balanced at first but when looking at light sport and saving weight we removed the balances and retested. There was no evidence of flutter.
We dive test every LSA Lightning to Vne, 180knts IAS ( 208mph) with proper attempts to induce flutter with no issues. It is required by the ASTM on every aircraft.
Nick Otterback
Arion Aircraft, LLC
From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of robert keen
Sent: Thursday, August 05, 2010 3:06 AM
To: lightning-list(at)matronics.com
Subject: Lightning Elevator flutter
Has anyone had a problem with elevator flutter? Can anyone tell me the mass balance limits of the lightning control surfaces?
Thanks Smokey | Quote: | | http://www.matronics.com/Navigator?Lightning-List |
0123456789
[quote][b]
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allanmaxe(at)yahoo.com
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| Posted: Thu Aug 05, 2010 5:21 am Post subject: Lightning Elevator flutter |
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Allan Maxwell yes call me at 504-813-8134 dont type much
--- On Thu, 8/5/10, robert keen <smokeysmail(at)bigpond.com> wrote:
| Quote: |
From: robert keen <smokeysmail(at)bigpond.com>
Subject: Lightning Elevator flutter
To: lightning-list(at)matronics.com
Date: Thursday, August 5, 2010, 3:06 AM
Has anyone had a problem with elevator flutter? Can anyone tell me the mass balance limits of the lightning control surfaces?
Thanks Smokey
| Quote: |
" target=_blank rel=nofollow>http://www.matronics.com/Navigator?Lightning-List
=nofollow>http://forums.matronics.com
blank rel=nofollow>http://www.matronics.com/contribution
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[quote][b]
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info(at)flylightning.net
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| Posted: Thu Aug 05, 2010 7:59 am Post subject: Lightning Elevator flutter |
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Allan’s is an esqual…different elevator and control design.
Nick
From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of Allan Maxwell
Sent: Thursday, August 05, 2010 7:45 AM
To: lightning-list(at)matronics.com
Subject: Re: Lightning-List: Lightning Elevator flutter
Allan Maxwell yes call me at 504-813-8134 dont type much
--- On Thu, 8/5/10, robert keen <smokeysmail(at)bigpond.com> wrote:
From: robert keen <smokeysmail(at)bigpond.com>
Subject: Lightning Elevator flutter
To: lightning-list(at)matronics.com
Date: Thursday, August 5, 2010, 3:06 AM
Has anyone had a problem with elevator flutter? Can anyone tell me the mass balance limits of the lightning control surfaces?
Thanks Smokey
| Quote: | | " target=_blank rel=nofollow>http://www.matronics.com/Navigator?Lightning-List=nofollow>http://forums.matronics.comblank rel=nofollow>http://www.matronics.com/contribution |
0123456789 | Quote: | | " target=_blank rel=nofollow>http://www.matronics.com/Navigator?Lightning-List |
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[quote][b]
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smokeysmail(at)bigpond.co
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| Posted: Sun Aug 08, 2010 2:14 pm Post subject: Lightning Elevator flutter |
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Nick,
I have experienced elevator flutter twice at around 140 knots indicated. I was told by the Australian agent Dennis, that it would be a loose tape under the wing.
I have not yet retaped the wing joint yet, but I would like the Mass Balance figures so I can check the elevator myself.
Can you send me the info please? I will keep you posted on what I find. Also do you have the mass balance figures for the ailerons?
Should the Lightning have bungie cords on the elevator pushrod to hold some weight?
Thanks Smokey.
From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of flylightning
Sent: Thursday, 5 August 2010 11:06 PM
To: lightning-list(at)matronics.com
Subject: RE: Lightning Elevator flutter
No. Did you experience this or just simply asking?
The prototype was mass balanced at first but when looking at light sport and saving weight we removed the balances and retested. There was no evidence of flutter.
We dive test every LSA Lightning to Vne, 180knts IAS ( 208mph) with proper attempts to induce flutter with no issues. It is required by the ASTM on every aircraft.
Nick Otterback
Arion Aircraft, LLC
From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of robert keen
Sent: Thursday, August 05, 2010 3:06 AM
To: lightning-list(at)matronics.com
Subject: Lightning Elevator flutter
Has anyone had a problem with elevator flutter? Can anyone tell me the mass balance limits of the lightning control surfaces?
Thanks Smokey | Quote: | | http://www.matronics.com/Navigator?Lightning-List http://forums.matronics.com http://www.matronics.com/contribution |
0123456789 | Quote: | | http://www.matronics.com/Navigator?Lightning-List |
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7
Internal Checked by AVG - www.avg.com
18:25:00
[quote][b]
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Bill Strahan
Joined: 20 Aug 2008
Posts: 145
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| Posted: Sun Aug 08, 2010 6:14 pm Post subject: Re: Lightning Elevator flutter |
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Perhaps I'm poorly educated on the subject, but I thought in most cases of control flutter the time between onset and airframe failure was less than it takes to say "hey what is that?"
I'm sure it's possible to have an episode of flutter, and even more likely to have some buzz that would precede flutter, and live to tell about it, but it seems very unlikely.
When I was testing 7RW I eventually worked my way to 200knots true with autopilot off and hands off the controls so the inertia of the system was as little as it could be. I did stick slaps at 190knots true and saw the system return to equilibrium at the same rate it had at every other speed up until that point.
That was enough to make me feel okay with the speeds at which I would be operating.
I hope that the results of this inquiry are shared on the list. I'm not concerned for 7RW but would like to find out what is learned in this situation.
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N1BZRich(at)AOL.COM
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| Posted: Sun Aug 08, 2010 7:12 pm Post subject: Lightning Elevator flutter |
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Hi Smokey,
I don't want to totally disagree with your flutter assessment, but I kind of doubt that what you felt was true elevator flutter. Here is why - Many other Lightning builders, during the 40 hour phase one test period, have flown their Lightnings to Vne without any hint of flutter. And in the case of the prototype, Nick and I have flown it to well beyond the published Vne in several different stabilizer/elevator configurations. First, with the full aerodynamic and dynamic counter balance, they with a lesser modified configuration (not as large an aerodynamic counterbalance), and finally with no aerodynamic counter balance at all. In each case, absolutely no flutter, or to be more specific not even any indication of flutter. So if your airplane is having a problem, something may be different about your airplane. But lets not totally rule it out yet until we know more from you.
So can you give us some more information to go on? For example, you said it happened twice at about 140 knots indicated. Was that the first two times you had your Lighting to 140 knots? Or has it been beyond that before with no problems on other occasions? When it happened, what did you feel (or see) to make you think elevator flutter? Was the stick moving? If so, could you freeze the stick with hand pressure? What did you do to case what ever was happening to stop happening? Did it stop immediately whey you did that? How much flying time on your airplane? Have you checked the elevator control system to see if there is excess slop in the system? Is anything looser now than before? I have seen at least one case where some rod end bearings developed some slop and the extra slop did cause some minor aileron buzz but no real buffet. Do you have the modification with the elevator trim tab? If so has that tab been there all along? And if so, how is the hinge for the tab? Has it loosened up? Sorry for all the questions, but these kind of things will help diagnose the problem and come up with a fix.
As Dennis hinted at, with no tape between the wing and the fuselage karman, you will probably have a higher stall speed and some strange buffet feelings, but it is not flutter. So you might want to check that area.
Other than the above, I can offer no other suggestions until we hear more from you. Nick will certainly jump in here when he see this on Monday morning. Rest assured that the Lightning is one of the more thoroughly tested designs out there. It is way stronger and thus safer than it has to be, but that is the basic design philosophy that Arion goes by - better than the others.
I look forward to hearing from you.
Blue Skies,
Buz
In a message dated 8/8/2010 6:15:48 P.M. Eastern Daylight Time, smokeysmail(at)bigpond.com writes:
| Quote: |
Nick,
I have experienced elevator flutter twice at around 140 knots indicated. I was told by the Australian agent Dennis, that it would be a loose tape under the wing.
I have not yet retaped the wing joint yet, but I would like the Mass Balance figures so I can check the elevator myself.
Can you send me the info please? I will keep you posted on what I find. Also do you have the mass balance figures for the ailerons?
Should the Lightning have bungie cords on the elevator pushrod to hold some weight?
Thanks Smokey.
From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of flylightning
Sent: Thursday, 5 August 2010 11:06 PM
To: lightning-list(at)matronics.com
Subject: RE: Lightning Elevator flutter
No. Did you experience this or just simply asking?
The prototype was mass balanced at first but when looking at light sport and saving weight we removed the balances and retested. There was no evidence of flutter.
We dive test every LSA Lightning to Vne, 180knts IAS ( 208mph) with proper attempts to induce flutter with no issues. It is required by the ASTM on every aircraft.
Nick Otterback
Arion Aircraft, LLC
From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of robert keen
Sent: Thursday, August 05, 2010 3:06 AM
To: lightning-list(at)matronics.com
Subject: Lightning Elevator flutter
Has anyone had a problem with elevator flutter? Can anyone tell me the mass balance limits of the lightning control surfaces?
Thanks Smokey | Quote: | | http://www.matronics.com/Navigator?Lightning-List http://forums.matronics.com http://www.matronics.com/contribution |
0123456789 | Quote: | | http://www.matronics.com/Navigator?Lightning-List |
0 | Quote: | | http://www.matronics.com/Navigator?Lightning-List |
1 | Quote: | | http://www.matronics.com/Navigator?Lightning-List |
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3 | Quote: | | http://www.matronics.com/Navigator?Lightning-List |
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7
Internal Checked by AVG - www.avg.com
18:25:00
| Quote: | | http://www.matronics.com/Navigator?Lightning-List |
8 |
[quote][b]
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http://www.matronics.com/Navigator?Lightning-List |
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davemcc
Joined: 28 Feb 2007
Posts: 74
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| Posted: Mon Aug 09, 2010 3:23 pm Post subject: Lightning Elevator flutter |
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Smokey
I have an Esqual, installed gap seals, had stick "shimmy" thinking it to be "flutter". Removed gap seals and all is good, this was happening at 135 to 140.
My question, do you have gap seals on?
Dave
[quote] ---
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http://www.matronics.com/Navigator?Lightning-List |
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smokeysmail(at)bigpond.co
Guest
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| Posted: Wed Aug 11, 2010 5:21 am Post subject: Lightning Elevator flutter |
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Yes I am sure you are correct I am currently removing gap seal and retaping wing roots, I am sure it will fix the problem. This is the only change to the aircraft from new.
Cheers Smokey
From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of Dave
Sent: Tuesday, 10 August 2010 9:22 AM
To: lightning-list(at)matronics.com
Subject: Re: Lightning Elevator flutter
Smokey
I have an Esqual, installed gap seals, had stick "shimmy" thinking it to be "flutter". Removed gap seals and all is good, this was happening at 135 to 140.
My question, do you have gap seals on?
Dave
| Quote: |
----- Original Message -----
From: robert keen (smokeysmail(at)bigpond.com)
To: lightning-list(at)matronics.com (lightning-list(at)matronics.com)
Sent: Sunday, August 08, 2010 5:13 PM
Subject: RE: Lightning-List: Lightning Elevator flutter
Nick,
I have experienced elevator flutter twice at around 140 knots indicated. I was told by the Australian agent Dennis, that it would be a loose tape under the wing.
I have not yet retaped the wing joint yet, but I would like the Mass Balance figures so I can check the elevator myself.
Can you send me the info please? I will keep you posted on what I find. Also do you have the mass balance figures for the ailerons?
Should the Lightning have bungie cords on the elevator pushrod to hold some weight?
Thanks Smokey.
From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of flylightning
Sent: Thursday, 5 August 2010 11:06 PM
To: lightning-list(at)matronics.com
Subject: RE: Lightning Elevator flutter
No. Did you experience this or just simply asking?
The prototype was mass balanced at first but when looking at light sport and saving weight we removed the balances and retested. There was no evidence of flutter.
We dive test every LSA Lightning to Vne, 180knts IAS ( 208mph) with proper attempts to induce flutter with no issues. It is required by the ASTM on every aircraft.
Nick Otterback
Arion Aircraft, LLC
From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of robert keen
Sent: Thursday, August 05, 2010 3:06 AM
To: lightning-list(at)matronics.com
Subject: Lightning Elevator flutter
Has anyone had a problem with elevator flutter? Can anyone tell me the mass balance limits of the lightning control surfaces?
Thanks Smokey | Quote: | | http://www.matronics.com/Navigator?Lightning-List http://forums.matronics.com http://www.matronics.com/contribution |
0123
Internal Checked by AVG - www.avg.com
18:25:00 45678 |
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9012345678
Internal Checked by AVG - www.avg.com
18:25:00
[quote][b]
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smokeysmail(at)bigpond.co
Guest
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| Posted: Wed Aug 11, 2010 5:22 am Post subject: Lightning Elevator flutter |
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All is in good condition and I think it is the gap seal on the elevator, will know soon. When I experienced the flutter like symptoms it was not possible to hold the elevator from moving up and down, it ceased as soon as I slowed a few knots and It only lasted a couple of seconds as I was increasing speed slowly at the time.
Cheers Smokey
From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of N1BZRich(at)aol.com
Sent: Monday, 9 August 2010 1:12 PM
To: lightning-list(at)matronics.com
Subject: Re: Lightning Elevator flutter
Hi Smokey,
I don't want to totally disagree with your flutter assessment, but I kind of doubt that what you felt was true elevator flutter. Here is why - Many other Lightning builders, during the 40 hour phase one test period, have flown their Lightnings to Vne without any hint of flutter. And in the case of the prototype, Nick and I have flown it to well beyond the published Vne in several different stabilizer/elevator configurations. First, with the full aerodynamic and dynamic counter balance, they with a lesser modified configuration (not as large an aerodynamic counterbalance), and finally with no aerodynamic counter balance at all. In each case, absolutely no flutter, or to be more specific not even any indication of flutter. So if your airplane is having a problem, something may be different about your airplane. But lets not totally rule it out yet until we know more from you.
So can you give us some more information to go on? For example, you said it happened twice at about 140 knots indicated. Was that the first two times you had your Lighting to 140 knots? Or has it been beyond that before with no problems on other occasions? When it happened, what did you feel (or see) to make you think elevator flutter? Was the stick moving? If so, could you freeze the stick with hand pressure? What did you do to case what ever was happening to stop happening? Did it stop immediately whey you did that? How much flying time on your airplane? Have you checked the elevator control system to see if there is excess slop in the system? Is anything looser now than before? I have seen at least one case where some rod end bearings developed some slop and the extra slop did cause some minor aileron buzz but no real buffet. Do you have the modification with the elevator trim tab? If so has that tab been there all along? And if so, how is the hinge for the tab? Has it loosened up? Sorry for all the questions, but these kind of things will help diagnose the problem and come up with a fix.
As Dennis hinted at, with no tape between the wing and the fuselage karman, you will probably have a higher stall speed and some strange buffet feelings, but it is not flutter. So you might want to check that area.
Other than the above, I can offer no other suggestions until we hear more from you. Nick will certainly jump in here when he see this on Monday morning. Rest assured that the Lightning is one of the more thoroughly tested designs out there. It is way stronger and thus safer than it has to be, but that is the basic design philosophy that Arion goes by - better than the others.
I look forward to hearing from you.
Blue Skies,
Buz
In a message dated 8/8/2010 6:15:48 P.M. Eastern Daylight Time, smokeysmail(at)bigpond.com writes:
| Quote: |
Nick,
I have experienced elevator flutter twice at around 140 knots indicated. I was told by the Australian agent Dennis, that it would be a loose tape under the wing.
I have not yet retaped the wing joint yet, but I would like the Mass Balance figures so I can check the elevator myself.
Can you send me the info please? I will keep you posted on what I find. Also do you have the mass balance figures for the ailerons?
Should the Lightning have bungie cords on the elevator pushrod to hold some weight?
Thanks Smokey.
From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of flylightning
Sent: Thursday, 5 August 2010 11:06 PM
To: lightning-list(at)matronics.com
Subject: RE: Lightning Elevator flutter
No. Did you experience this or just simply asking?
The prototype was mass balanced at first but when looking at light sport and saving weight we removed the balances and retested. There was no evidence of flutter.
We dive test every LSA Lightning to Vne, 180knts IAS ( 208mph) with proper attempts to induce flutter with no issues. It is required by the ASTM on every aircraft.
Nick Otterback
Arion Aircraft, LLC
From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of robert keen
Sent: Thursday, August 05, 2010 3:06 AM
To: lightning-list(at)matronics.com
Subject: Lightning Elevator flutter
Has anyone had a problem with elevator flutter? Can anyone tell me the mass balance limits of the lightning control surfaces?
Thanks Smokey | Quote: | | http://www.matronics.com/Navigator?Lightning-List http://forums.matronics.com http://www.matronics.com/contribution |
0123
Internal Checked by AVG - www.avg.com
18:25:00
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18:25:00
[quote][b]
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selwyn
Joined: 12 Mar 2008
Posts: 102
Location: Australia
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| Posted: Fri Aug 13, 2010 3:46 am Post subject: Re: Lightning Elevator flutter |
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Hi Smokey,
Interested to hear your experiences, I hope to be flying in about a week so I have all this to look forward to.
What type of gap elevator gap seal did you have on, just tape along the hinge line? And, does anyone care to speculate on why gap seals would promote flutter (or whatever it was that was going on)?
Buzz, in relation to your comment about some rod end fittings developing free play, as I'm sure others have noticed, some of them come out of the packet with free play built in. Is there any good data on the allowable free play in the control circuits, especially the ailerons?
| smokeysmail(at)bigpond.co wrote: | All is in good condition and I think it is the gap seal on the elevator, will know soon. When I experienced the flutter like symptoms it was not possible to hold the elevator from moving up and down, it ceased as soon as I slowed a few knots and It only lasted a couple of seconds as I was increasing speed slowly at the time.
Cheers Smokey
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Cheers, Selwyn
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N1BZRich(at)aol.com
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| Posted: Sun Aug 15, 2010 7:09 am Post subject: Lightning Elevator flutter |
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Selwyn
Good luck on that upcoming first flight. Hopefully you will send us all an announcement and some photos for the newsletter.
As to your question about rod end free play, I am not aware of the allowable free play limit for any "go" or "no go" decision on using them out of the box. I suspect that the problem was just a batch that all had the upped limit, what ever that is. The aileron control design has three rod ends in close proximity at the aileron bell crank and aileron control horn. In the case that I was talking about, with three that close together, it allowed the trailing edge of the aileron to be moved almost a half inch up and down when the stick was held in the center position. This movement was more than I had seen on other Lightnings or Esqual. Being this loose allowed the ailerons to "buzz" up and down in some flight situations. Initially we solved the "buzzing" by reflexing each aileron up slightly which put an air load on them and prevented the "buzz", but the real fix was replacing the rod ends with new ones. I suspect that the aileron "buzzing" in flight caused the rod ends to loosen up even more than they initially had been. Hope this helps.
Blue Skies,
Buz
In a message dated 8/13/2010 7:47:35 A.M. Eastern Daylight Time, selwyn(at)ellisworks.com.au writes:
| Quote: | --> Lightning-List message posted by: "selwyn" <selwyn(at)ellisworks.com.au>
Hi Smokey,
Interested to hear your experiences, I hope to be flying in about a week so I have all this to look forward to.
What type of gap elevator gap seal did you have on, just tape along the hinge line? And, does anyone care to speculate on why gap seals would promote flutter (or whatever it was that was going on)?
Buzz, in relation to your comment about some rod end fittings developing free play, as I'm sure others have noticed, some of them come out of the packet with free play built in. Is there any good data on the allowable free play in the control circuits, especially the ailerons?
smokeysmail(at)bigpond.co wrote:
| Quote: | All is in good condition and I think it is the gap seal on the elevator, will know soon. When I experienced the flutter like symptoms it was not possible to hold the elevator from moving up and down, it ceased as soon as I slowed a few knots and It only lasted a couple of seconds as I was increasing speed slowly at the time.
Cheers Smokey
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Cheers, Selwyn
Kit 66
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selwyn
Joined: 12 Mar 2008
Posts: 102
Location: Australia
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| Posted: Mon Aug 16, 2010 12:32 am Post subject: Re: Lightning Elevator flutter |
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Hi Buzz,
Yeah, the aileron circuit is the critical one because of the short lever arm and the number of bearings. I was more thinking of allowable backlash at the trailing edge of the aileron rather than that in the individual bearings. I certainly don't have anything like a half inch but there is some and I was looking for some information on acceptable limits.
Just at the moment I have two things on my to do list so the day must be getting close. I'm aiming for C of A inspection on Thursday.
The gap seal issue also continues to intrigue me.
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smokeysmail(at)bigpond.co
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| Posted: Tue Aug 17, 2010 2:01 am Post subject: Lightning Elevator flutter |
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The sealing tape was placed over the top and stuck to both surfaces, with a
mylar seal on the bottom. See how it goes.
The rod end play is also an issue on this lightning when it gets a little
bumpy the ailerons move up and down.
The rod ends have too much play , not wear. I will replace them and that
will cure the problem there.
Cheers Smokey
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