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Canopy Skirt Buzz...

 
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Matt Dralle
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Joined: 08 Nov 2005
Posts: 26321
Location: Livermore CA USA
PostPosted: Sat Oct 30, 2010 5:14 pm    Post subject: Canopy Skirt Buzz... Reply with quote
Hello Listers,

After the very first flight on the RV-8, I discovered that the fiberglass skirts around the canopy loved to buzz against the turtle deck skin at anything over about 100mph. To soften the intersection between the skirt and the skin I added a row of Velcro-brand "loops" tape all the way around the base of the canopy skirt on the inside including around the bottom of the windscreen so that when the canopy was closed any skin to skirt areas were cushioned with a thickness of the Velcro.

That worked great and totally eliminated the buzzing and also sealed up the cabin nicely. I was pleased.

But, after a Summer in California and 112 hours of flying, the Velcro just didn't hold up. In the Summer sun, the glue became gooey and the tape slipped out of position along the curve behind the passenger and looked like grandma's slip was showing. Along the extreme rear where the skirts come together and the fit is pretty tight, the glue squeezed out from the heat and kind of goo-ed all around on the metal.

So, I removed the skirts a couple of weekends ago and literally spend a whole weekend removing the Velcro and all of the glue. I was lucky and the in the process I didn't remove any of the textured paint on the skirts or windscreen frame - whew, that was a scary two days.

This weekend I finally got to take her out for a flight after the oil cooler replacement (all went fine, btw) and try out the new "tape-less" installation.

Holy COW!! It was SOOOOOO noisy! At 200mph I took the headphones off and couldn't believe the DB level. I really couldn't stand the noise level with the headphone ON, and without then it just plain hurt. I slowed down to about 150mph and the noise decreased slightly, but not that much. I slowed down to a stall and finally the buzzing stopped, but as soon as I pushed the nose over and speeded up a little it started again.

Obviously I'm going to have to put something like the Velco back on the inside of the canopy frame. But what? I'm guessing that all RV-8's must have this issue. I surprised there isn't something in the plans to deal with it. Is there some magic tape/insulator that people are using for this that will hold up in the heat of the Summer sun?

Thanks in advance!

-
Matt Dralle
RV-8 #82880 N998RV
http://www.mattsrv8.com - Matt's RV-8 Construction Blog
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 112+ Hours Total Time Since May 2 2010 Test Flight!

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fherr(at)cfl.rr.com
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PostPosted: Sat Oct 30, 2010 5:40 pm    Post subject: Canopy Skirt Buzz... Reply with quote
Matt,

Is there room for a thin Delrin strip (e.g., 1/6" thick by 1" wide) in place of the velcro? Countersunk pop rivets could hold it on and it would fill the space.
See McMaster-Carr catalog (white): http://www.mcmaster.com/#plastics/=9i9osy. Colors are white, off-white, brown, and black. The strips can also be "shaved" to fit. Just a thought.
Francis
RV-7A N968BF
12.1 hours and testing is going very well.

On Oct 30, 2010, at 9:12 PM, Matt Dralle wrote:
--> RV7-List message posted by: Matt Dralle <dralle(at)matronics.com (dralle(at)matronics.com)>

Hello Listers,

After the very first flight on the RV-8, I discovered that the fiberglass skirts around the canopy loved to buzz against the turtle deck skin at anything over about 100mph. To soften the intersection between the skirt and the skin I added a row of Velcro-brand "loops" tape all the way around the base of the canopy skirt on the inside including around the bottom of the windscreen so that when the canopy was closed any skin to skirt areas were cushioned with a thickness of the Velcro.

That worked great and totally eliminated the buzzing and also sealed up the cabin nicely. I was pleased.

But, after a Summer in California and 112 hours of flying, the Velcro just didn't hold up. In the Summer sun, the glue became gooey and the tape slipped out of position along the curve behind the passenger and looked like grandma's slip was showing. Along the extreme rear where the skirts come together and the fit is pretty tight, the glue squeezed out from the heat and kind of goo-ed all around on the metal.

So, I removed the skirts a couple of weekends ago and literally spend a whole weekend removing the Velcro and all of the glue. I was lucky and the in the process I didn't remove any of the textured paint on the skirts or windscreen frame - whew, that was a scary two days.

This weekend I finally got to take her out for a flight after the oil cooler replacement (all went fine, btw) and try out the new "tape-less" installation.

Holy COW!! It was SOOOOOO noisy! At 200mph I took the headphones off and couldn't believe the DB level. I really couldn't stand the noise level with the headphone ON, and without then it just plain hurt. I slowed down to about 150mph and the noise decreased slightly, but not that much. I slowed down to a stall and finally the buzzing stopped, but as soon as I pushed the nose over and speeded up a little it started again.

Obviously I'm going to have to put something like the Velco back on the inside of the canopy frame. But what? I'm guessing that all RV-8's must have this issue. I surprised there isn't something in the plans to deal with it. Is there some magic tape/insulator that people are using for this that will hold up in the heat of the Summer sun?

Thanks in advance!

-
Matt Dralle
RV-8 #82880 N998RV
http://www.mattsrv8.com - Matt's RV-8 Construction Blog
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 112+ Hours Total Time Since May 2 2010 Test - The RV7-List --> http://www.matronics.========================[b]http://www.matronics.com/co=================

[quote][b]

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ceengland(at)bellsouth.ne
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PostPosted: Sun Oct 31, 2010 7:32 am    Post subject: Canopy Skirt Buzz... Reply with quote
On 10/30/2010 8:12 PM, Matt Dralle wrote:
Quote:


Hello Listers,

After the very first flight on the RV-8, I discovered that the fiberglass skirts around the canopy loved to buzz against the turtle deck skin at anything over about 100mph. To soften the intersection between the skirt and the skin I added a row of Velcro-brand "loops" tape all the way around the base of the canopy skirt on the inside including around the bottom of the windscreen so that when the canopy was closed any skin to skirt areas were cushioned with a thickness of the Velcro.

That worked great and totally eliminated the buzzing and also sealed up the cabin nicely. I was pleased.

But, after a Summer in California and 112 hours of flying, the Velcro just didn't hold up. In the Summer sun, the glue became gooey and the tape slipped out of position along the curve behind the passenger and looked like grandma's slip was showing. Along the extreme rear where the skirts come together and the fit is pretty tight, the glue squeezed out from the heat and kind of goo-ed all around on the metal.

So, I removed the skirts a couple of weekends ago and literally spend a whole weekend removing the Velcro and all of the glue. I was lucky and the in the process I didn't remove any of the textured paint on the skirts or windscreen frame - whew, that was a scary two days.

This weekend I finally got to take her out for a flight after the oil cooler replacement (all went fine, btw) and try out the new "tape-less" installation.

Holy COW!! It was SOOOOOO noisy! At 200mph I took the headphones off and couldn't believe the DB level. I really couldn't stand the noise level with the headphone ON, and without then it just plain hurt. I slowed down to about 150mph and the noise decreased slightly, but not that much. I slowed down to a stall and finally the buzzing stopped, but as soon as I pushed the nose over and speeded up a little it started again.

Obviously I'm going to have to put something like the Velco back on the inside of the canopy frame. But what? I'm guessing that all RV-8's must have this issue. I surprised there isn't something in the plans to deal with it. Is there some magic tape/insulator that people are using for this that will hold up in the heat of the Summer sun?

Thanks in advance!

-
Matt Dralle
RV-8 #82880 N998RV
http://www.mattsrv8.com - Matt's RV-8 Construction Blog
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 112+ Hours Total Time Since May 2 2010 Test Flight!
If you liked the results you got with the velcro, except the creeping

glue (apologies to Halloween...), You might try using regular velcro
without the adhesive & gluing it on with epoxy.

I don't have any experience using it on a canopy skirt, but I've done it
to the backs of various PDAs & other handheld gadgets, & it seems to
work fine in the plane. I've typically used el-cheapo hardware store
tubes, so if you have any high quality stuff left over it should work
even better.

Charlie

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Matt Dralle
Site Admin


Joined: 08 Nov 2005
Posts: 26321
Location: Livermore CA USA
PostPosted: Sun Oct 31, 2010 9:04 am    Post subject: Canopy Skirt Buzz... Reply with quote
At 09:45 AM 10/31/2010 Sunday, you wrote:
Quote:

Matt,
I haven't had that problem.
Stan Sutterfield
I'm guessing that all RV-8's must have this issue.


Stan,

Wow, really? Do you have anything between the fiberglass skirt and the top of the turtledeck? Foam, velcro, etc?

Do you have a perfectly tight fit all the way around? I've got a little pooch on both sides kind of at the center of the concave, roundy part.

One thing I forgot to mention in my original post was that I tried unlatching the canopy to see what impact it would have. The buzz got even louder.

Another thing I tried was adjusting the Prop RPM. There was definately a relationship between the buzz and the RPM, not related to speed of the aircraft. A harmonic of sorts.

Another odd behavior was that when I was climbing out, I didn't hear it at all. It wasn't until I pushed the nose over and started picking up speed that it started.

Matt
-
Matt Dralle
RV-8 #82880 N998RV
http://www.mattsrv8.com - Matt's RV-8 Construction Log
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 111+ Hours TTSN - The Fun Never Stops...

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