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  #1  
Old 06-01-2020, 05:46 PM
DennisRhodes DennisRhodes is offline
 
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Location: Taylorsville, Ga
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Default RV 9 Inboard flap faring issues

On an RV9 or 9A there's a fairing on the bottom side adjacent to the fuselage that covers up a small cavity at the end of each side flap. This is close proximity to the linkage that operates the flap mechanism. The fairing for this area is a extended piece of fuselage skin which must move with the extension of that Fowler type flap.

After about 750 hours I began to get some vibration noise from that fairing because its only held tight against the fuselage bottom from the spring back in the metal. I suspect the airflow is causing it to vibrate against the fuselage and or flap bracket and causing the noise. Also seeing some cracks and other indications on this moveable piece of fuselage skin was wondering if others have noticed this.

If so, has anyone just completely removed this section and left the hole exposed. Or has anyone come up with a better idea to utilize the fairing or modify the fairing to get a tighter seal . Interested in your comments or ideas for a fix. I'll try to add a link for pic on a later edit.

https://photos.app.goo.gl/atHJkLK7xykgeEMS8
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Last edited by DennisRhodes : 06-01-2020 at 08:59 PM. Reason: added link
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  #2  
Old 06-01-2020, 05:54 PM
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scard scard is offline
 
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I haven't seen any such symptoms on ours.
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  #3  
Old 06-01-2020, 06:28 PM
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Steve Melton Steve Melton is online now
 
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if I remember the Van's RV-9 correctly. it was extensively trimmed away from the fuselage.

I found some photo's of Van's RV-9 from several yrs ago. appears used and abused. it had some high flight hours back then. I wonder what the fight hrs are now?





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RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 900+ for all

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Last edited by Steve Melton : 06-01-2020 at 07:40 PM.
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  #4  
Old 06-01-2020, 09:06 PM
DennisRhodes DennisRhodes is offline
 
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Default RV9 fairing at flap inboard at Fuselage

I think I added a shared link that should provide a pic of area in question and a 13 sec video . Please let me know if that doesn't load up correctly.
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  #5  
Old 06-02-2020, 03:55 PM
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Steve Melton Steve Melton is online now
 
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Default mine

I think the Van's design could have been improved from the outset but it is what it is. flap bracket fairings are three years old. installed a never removed.





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Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 900+ for all

Simplicity is the art in design.
I was born an airplane nut. I have no explanation for it.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com

Last edited by Steve Melton : 06-02-2020 at 04:17 PM.
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  #6  
Old 06-02-2020, 08:51 PM
DennisRhodes DennisRhodes is offline
 
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Steve, you can see on mine where it has had some contact with the flap bracket , That has since been cleared so that it doesn't rub, but I think that is actually what set up the airflow vibration buzz I'm now hearing.

I like all your printed " Go Fasters " on that bracket pic you posted, my fairing definitely does not have the flexibility i see in those after 10 years and 750 hrs .

Not real sure how I'm going to address this, would like to just remove the cover and leave the cavity open . It already has the RV9 signature whistle, but not interested in adding a second one! Once that cover plate is removed not going to be that easy to reinstall back short of some blind rivets.
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  #7  
Old 06-02-2020, 09:33 PM
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Steve Melton Steve Melton is online now
 
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open cavities create drag. you have cleared the interference, that's the important step. I just live with mine because I can't think of anything better at the moment. I believe the RV9 characteristic whistle is from the elevator hinges but maybe this flap cover contributes.
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Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 900+ for all

Simplicity is the art in design.
I was born an airplane nut. I have no explanation for it.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com

Last edited by Steve Melton : 06-02-2020 at 09:48 PM.
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  #8  
Old 06-03-2020, 07:46 AM
DennisRhodes DennisRhodes is offline
 
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Yes, that signature whistle is from the horizontal. Thanks for the coments. Was thinking about blind riveting a piece over the existing to bring the flexibility back and bending a 1/4 inch 30 deg angle on the trailing edge to allow the airflow to kick it up against the stops . That would solve most all problems .
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Last edited by DennisRhodes : 06-03-2020 at 07:55 AM.
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  #9  
Old 06-03-2020, 06:48 PM
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OZCleco OZCleco is offline
 
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Was thinking about blind riveting a piece over the existing to bring the flexibility back and bending a 1/4 inch 30 deg angle on the trailing edge

That's what I'd be doing to ours in the event they cracked.

The airframe is 17 years old and these buggars droop on both sides. Glad to know where that whistle comes from. I thought it was just ours.
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  #10  
Old 06-04-2020, 09:23 AM
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rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by Steve Melton View Post
if I remember the Van's RV-9 correctly. it was extensively trimmed away from the fuselage.

I found some photo's of Van's RV-9 from several yrs ago. appears used and abused. it had some high flight hours back then. I wonder what the fight hrs are now?
The RV-9A demonstrator was the actual prototype (Aircraft #1, built from the first prototype parts). In a case like that, it is not unusual for there to be minor deviations that need to be resolved (like the inboard end of the flap on the prototype).

N129RV now has a bit over 2850 hrs in its 21 years of service, so yes, it shows its age, but proudly. A lot of the wear and tear occurs at shows like OSH. Hundreds of people every day climbing in and out with zero experience doing so. Often times blatantly ignoring the "PLEASE ASK A VANS EMPLOYEE FOR HELP BEFORE ENTERING" sign.

We affectionately refer to all of the airplanes as adult playground equipment.

As for the OP's comment about the flap gap seal. Even with the high hrs in service, the ones on the prototype are still working as designed and fit close when flaps are retracted. Your photos indicate that the edge of the fairing has been rubbing on the side of the flap hinge bracket (paint scraped away). The wavy distorted appearance makes it look like they have been bent and straightened numerous times. This appearance is not typical to RV-9's just because they have a bunch of flight hrs. It is not caused by vibration/flutter of the fairing.

In situations where they appear to be slack slightly on other RV-9's, I think they are probably tight in flight.... there is higher air pressure on the bottom surface of the fuselage just like the wings which should keep the fairing closed, but I don't have any video to confirm.
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Last edited by rvbuilder2002 : 06-04-2020 at 09:28 AM.
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