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robin1(at)mrmoisture.com
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 Posted: Tue Jun 12, 2007 1:02 pm Post subject: Tunnel Heat |
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Dear List,
I have read & re-read the archives regarding the tunnel heat issue and I am a bit confused. It seems some people have solved their heat issue but there doesn’t seem to be a consensus as to the proper way to resolve it and that the “fix” is more like a series of small corrections rather than just one modification.
From my reading of the archives that heat enters the tunnel due to a number of reasons:
<![if !supportLists]>· <![endif]>Radiant heat from exhaust stack
<![if !supportLists]>· <![endif]>Radiant heat from small cowl opening
<![if !supportLists]>· <![endif]>Heat leaking in from poorly sealed heater boxes
<![if !supportLists]>· <![endif]>Lack of air flow thru tunnel allowing hot air to build
From what I can tell the most common solutions are:
<![if !supportLists]>· <![endif]>Insulated false floor
<![if !supportLists]>· <![endif]>Pilots side firewall insulation
<![if !supportLists]>· <![endif]>Engine side insulation (stick on or spray on)
<![if !supportLists]>· <![endif]>Additional gill vents on the underside of the cowl
<![if !supportLists]>· <![endif]>Proper sealing of heater boxes
<![if !supportLists]>· <![endif]>Cool air venting of tunnel
Unfortunately my full fuel system is already in place and adding the false floor would be a challenge at this point. I am considering placing an OAT sensor in the tunnel to monitor the temps.
One last note: we are planning to use the SJ Cold Induction cowl and plenum with our BPE Cold Induction IO-540.
Can I get a consensus (metaphysical impossibility on the RV-List) as to the best way(s) to prevent this issue based on having my fuel system in place and assuming we will to a top job of sealing the heater boxes?
Thanks in advance for your consideration.
Robin Marks
RV-4 Sold
RV-6A 350 Hours
RV-10 Parts, parts, parts N456RV Reserved
[quote][b]
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Deems Davis
Joined: 09 Jan 2006
Posts: 925
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| Posted: Tue Jun 12, 2007 1:32 pm Post subject: Tunnel Heat |
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Robin, I was similarly confused/worried by the reports/solutions
regarding tunnel heat. There are strong feeling about the source and the
solution/s. in the end I reasoned that the biggest heat producer was
forward of the firewall, and the best thing I could do was insulate the
firewall. I ended up putting a fiberfrax thermal barrier between the
original firewall and a 'faux' firewall that I placed on top of it. I
also put a fiberfrax insulation barrier between the heater control boxes
and the firewall's. There is a theory that some of the heat comes from
the exhaust. If you order the John Forsling exhaust with the
'turn-downs' to go with your BPE cold air, the exhaust is extended
further back.aft and away from the bottom of the fuse. here's links to
some pictures.
http://deemsrv10.com/album/Sec%2041%20Upper%20Fwd%20Fuse%20Install/slides/DSC03240.html
Click forward and back to see other pictures.
http://deemsrv10.com/album/Sec%20FF6%20Exhaust%20System/slides/DSC04747.html
I have the plenum and the James Cowl and I don't seen (and haven't made)
any changes relative to tunnel heat. There are several reports that
adding vents to the bottom of the cowl improves CHT cooling, but none
from anyone with the James cowl/plenum, I'm holding off until I fly to
determine if it's necessary.
Deems Davis # 406
Baffling / Plenum / Engine Stuff
http://deemsrv10.com/
Robin Marks wrote:
| Quote: |
Dear List,
I have read & re-read the archives regarding the tunnel heat issue and
I am a bit confused. It seems some people have solved their heat issue
but there doesn’t seem to be a consensus as to the proper way to
resolve it and that the “fix” is more like a series of small
corrections rather than just one modification.
From my reading of the archives that heat enters the tunnel due to a
number of reasons:
· Radiant heat from exhaust stack
· Radiant heat from small cowl opening
· Heat leaking in from poorly sealed heater boxes
· Lack of air flow thru tunnel allowing hot air to build
From what I can tell the most common solutions are:
· Insulated false floor
· Pilots side firewall insulation
· Engine side insulation (stick on or spray on)
· Additional gill vents on the underside of the cowl
· Proper sealing of heater boxes
· Cool air venting of tunnel
Unfortunately my full fuel system is already in place and adding the
false floor would be a challenge at this point. I am considering
placing an OAT sensor in the tunnel to monitor the temps.
One last note: we are planning to use the SJ Cold Induction cowl and
plenum with our BPE Cold Induction IO-540.
Can I get a consensus (metaphysical impossibility on the RV-List) as
to the best way(s) to prevent this issue based on having my fuel
system in place and assuming we will to a top job of sealing the
heater boxes?
Thanks in advance for your consideration.
Robin Marks
RV-4 Sold
RV-6A 350 Hours
RV-10 Parts, parts, parts N456RV Reserved
*
*
|
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http://www.matronics.com/Navigator?RV10-List |
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ScooterF15
Joined: 19 Jun 2006
Posts: 136
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| Posted: Tue Jun 12, 2007 1:35 pm Post subject: Tunnel Heat |
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Robin,
I had the fuel system in before I heard anyone mention tunnel heat and I
wasn't about to go tearing things out. My suggestion is to wait and see if you
have a problem with your particular set up before you start 'fixing' anything.
You may have read my post about my tunnel heat solutions.
_http://forum.matronics.com/viewtopic.php?t=13430_
(http://forum.matronics.com/viewtopic.php?t=13430)
The small fiberglass trimming I did on the aft edge of the "reverse scoop"
under the belly made all the difference for me. Someday I may do some testing
to figure out exactly why that made such a change, but for now I'm happy that
tunnel heat is not a problem.
So, my vote is: Don't worry about it and keep building.
Good luck.
-Jim
40134
In a message dated 6/12/2007 5:04:57 P.M. Eastern Daylight Time,
robin1(at)mrmoisture.com writes:
Dear List,
I have read & re-read the archives regarding the tunnel heat issue and I am
a bit confused. It seems some people have solved their heat issue but there
doesn’t seem to be a consensus as to the proper way to resolve it and that the
“fix” is more like a series of small corrections rather than just one
modification.
| Quote: | From my reading of the archives that heat enters the tunnel due to a number
of reasons:
|
· Radiant heat from exhaust stack
· Radiant heat from small cowl opening
· Heat leaking in from poorly sealed heater boxes
· Lack of air flow thru tunnel allowing hot air to build
| Quote: | From what I can tell the most common solutions are:
· Insulated false floor
|
· Pilots side firewall insulation
· Engine side insulation (stick on or spray on)
· Additional gill vents on the underside of the cowl
· Proper sealing of heater boxes
· Cool air venting of tunnel
Unfortunately my full fuel system is already in place and adding the false
floor would be a challenge at this point. I am considering placing an OAT
sensor in the tunnel to monitor the temps.
One last note: we are planning to use the SJ Cold Induction cowl and plenum
with our BPE Cold Induction IO-540.
Can I get a consensus (metaphysical impossibility on the RV-List) as to the
best way(s) to prevent this issue based on having my fuel system in place and
assuming we will to a top job of sealing the heater boxes?
Thanks in advance for your consideration.
Robin Marks
RV-4 Sold
RV-6A 350 Hours
RV-10 Parts, parts, parts N456RV Reserved
Jim "Scooter" McGrew
_http://www.mit.edu/~jsmcgrew_ (http://www.mit.edu/~jsmcgrew)
************************************** See what's free at http://www.aol.com
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV10-List |
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Tim Olson
Joined: 25 Jan 2007
Posts: 2879
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| Posted: Tue Jun 12, 2007 1:56 pm Post subject: Tunnel Heat |
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Robin,
I basically agree with Jim's reply to this question. Don't go sweating
about it all too much until you see that there is something to worry
about. I took just a few small basic steps before I flew (nothing
involving a false floor), and once again last week when I went flying
and got asked the tunnel heat question, I put my bare, sandal'd foot
against the tunnel. It was just the slightest bit warm, and not at
all hot. Do some firewall insulation, forward or aft (aft will also
help with deadening any interior cabin noises being reflected around),
stand off your heat valves with an insulator, and do some insulating
inside your tunnel and you're probably just fine. I added the
SCAT tube insulation this spring and I think that helps a bit too.
When you open the heat valves and turn on the heat, you definitely
will drastically raise the air temp in the tunnel, so insulating
those SCAT tubes and associated end T's will help keep that sealed
in a bit. I find it almost laughable that today people even consider
it a tunnel heat "problem", because I think that for most people
a few simple common-sense tweaks is all it will take...certainly
nothing to be overwhelmed with. 230+ hours of flying experience.
Look at Vic...I think he's just approaching 500 now. Ray is over
200 too. If there were a major issue, there are enough flying
hours being put on some of these -10's that you'd hear some
complaints if the simple things weren't plenty to take care of
the heat. I'm waiting for someone to put 2" of insulation on
the forward side of the firewall, completely louvre cover their
cowl bottom, and start putting fans in the tunnel with NACA vents
to direct air through the tunnel, all to fix a pretty minor issue.
Tim Olson - RV-10 N104CD - Flying
do not archive
Robin Marks wrote:
| Quote: | Dear List,
I have read & re-read the archives regarding the tunnel heat
issue and I am a bit confused. It seems some people have solved their
heat issue but there doesn’t seem to be a consensus as to the proper way
to resolve it and that the “fix” is more like a series of small
corrections rather than just one modification.
From my reading of the archives that heat enters the tunnel
due to a number of reasons:
· Radiant heat from exhaust stack
· Radiant heat from small cowl opening
· Heat leaking in from poorly sealed heater boxes
· Lack of air flow thru tunnel allowing hot air to build
From what I can tell the most common solutions are:
· Insulated false floor
· Pilots side firewall insulation
· Engine side insulation (stick on or spray on)
· Additional gill vents on the underside of the cowl
· Proper sealing of heater boxes
· Cool air venting of tunnel
Unfortunately my full fuel system is already in place and adding the
false floor would be a challenge at this point. I am considering placing
an OAT sensor in the tunnel to monitor the temps.
One last note: we are planning to use the SJ Cold Induction cowl and
plenum with our BPE Cold Induction IO-540.
Can I get a consensus (metaphysical impossibility on the RV-List) as to
the best way(s) to prevent this issue based on having my fuel system in
place and assuming we will to a top job of sealing the heater boxes?
Thanks in advance for your consideration.
Robin Marks
RV-4 Sold
RV-6A 350 Hours
RV-10 Parts, parts, parts N456RV Reserved
*
*
|
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV10-List |
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gorejr(at)bellsouth.net
Guest
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| Posted: Tue Jun 12, 2007 1:58 pm Post subject: Tunnel Heat |
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Could you give us some specifics about the fiberfrax thermal barrier? Application method and supplier? Thanks. Jim
When are you going to be ready to fly? I am waiting on Will James to make my cowl after several of you folks with Barrett cold air induction and plenum get some egt and cht #'s.
| Quote: |
From: Deems Davis <deemsdavis(at)cox.net>
Date: 2007/06/12 Tue PM 04:31:38 EST
To: rv10-list(at)matronics.com
Subject: Re: Tunnel Heat
Robin, I was similarly confused/worried by the reports/solutions
regarding tunnel heat. There are strong feeling about the source and the
solution/s. in the end I reasoned that the biggest heat producer was
forward of the firewall, and the best thing I could do was insulate the
firewall. I ended up putting a fiberfrax thermal barrier between the
original firewall and a 'faux' firewall that I placed on top of it. I
also put a fiberfrax insulation barrier between the heater control boxes
and the firewall's. There is a theory that some of the heat comes from
the exhaust. If you order the John Forsling exhaust with the
'turn-downs' to go with your BPE cold air, the exhaust is extended
further back.aft and away from the bottom of the fuse. here's links to
some pictures.
http://deemsrv10.com/album/Sec%2041%20Upper%20Fwd%20Fuse%20Install/slides/DSC03240.html
Click forward and back to see other pictures.
http://deemsrv10.com/album/Sec%20FF6%20Exhaust%20System/slides/DSC04747.html
I have the plenum and the James Cowl and I don't seen (and haven't made)
any changes relative to tunnel heat. There are several reports that
adding vents to the bottom of the cowl improves CHT cooling, but none
from anyone with the James cowl/plenum, I'm holding off until I fly to
determine if it's necessary.
Deems Davis # 406
Baffling / Plenum / Engine Stuff
http://deemsrv10.com/
Robin Marks wrote:
>
> Dear List,
>
> I have read & re-read the archives regarding the tunnel heat issue and
> I am a bit confused. It seems some people have solved their heat issue
> but there doesn?t seem to be a consensus as to the proper way to
> resolve it and that the ?fix? is more like a series of small
> corrections rather than just one modification.
>
> From my reading of the archives that heat enters the tunnel due to a
> number of reasons:
>
> · Radiant heat from exhaust stack
>
> · Radiant heat from small cowl opening
>
> · Heat leaking in from poorly sealed heater boxes
>
> · Lack of air flow thru tunnel allowing hot air to build
>
> From what I can tell the most common solutions are:
>
> · Insulated false floor
>
> · Pilots side firewall insulation
>
> · Engine side insulation (stick on or spray on)
>
> · Additional gill vents on the underside of the cowl
>
> · Proper sealing of heater boxes
>
> · Cool air venting of tunnel
>
> Unfortunately my full fuel system is already in place and adding the
> false floor would be a challenge at this point. I am considering
> placing an OAT sensor in the tunnel to monitor the temps.
>
> One last note: we are planning to use the SJ Cold Induction cowl and
> plenum with our BPE Cold Induction IO-540.
>
> Can I get a consensus (metaphysical impossibility on the RV-List) as
> to the best way(s) to prevent this issue based on having my fuel
> system in place and assuming we will to a top job of sealing the
> heater boxes?
>
> Thanks in advance for your consideration.
>
> Robin Marks
>
> RV-4 Sold
>
> RV-6A 350 Hours
>
> RV-10 Parts, parts, parts N456RV Reserved
>
> *
>
>
> *
|
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV10-List |
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Deems Davis
Joined: 09 Jan 2006
Posts: 925
|
| Posted: Tue Jun 12, 2007 4:45 pm Post subject: Tunnel Heat |
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FiberFrax is a light weight thermal insulation which can withstand temps
to 2400 degrees. It's available in a cloth like blanket aprox 3/32 "
thick. It's applied with its own adhesive. However if anyone wants to
pursue this, I have 2 bottles of adhesive I'd be happy to give away.
Caution the adhesive does NOT work well with Stainless steel, I used it
to put and hold in place while I put the stainless steel sandwich
together w/ rivets.
I 1st became aware of it when building a Long EZ, it was used as an
insulation blanket between the Rear bulkhead/firewall made from marine
plywood and the stainless steel heat/fire shield on the engine side.
Here's a link to Aircraft Spruce site:
http://www.aircraftspruce.com/catalog/appages/fiberfrax.php
There are at lest 2 other alternatives to fiber frax.
Cool Mat
Zyrtex
Deems Davis # 406
Baffling / Plenum / Engine Stuff
http://deemsrv10.com/
gorejr(at)bellsouth.net wrote:
| Quote: |
Could you give us some specifics about the fiberfrax thermal barrier? Application method and supplier? Thanks. Jim
When are you going to be ready to fly? I am waiting on Will James to make my cowl after several of you folks with Barrett cold air induction and plenum get some egt and cht #'s.
> Fr
|
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Deems Davis
Joined: 09 Jan 2006
Posts: 925
|
| Posted: Tue Jun 12, 2007 4:50 pm Post subject: Tunnel Heat |
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| Quote: | When are you going to be ready to fly?
|
Good question.... Sometime this year hopefully, best guess at this time
OCT. However, there is another RV-10 BPE cold air w/ James cowl/plenum
ahead of me. I just spoke to Gary Foster in OK, a couple of day's ago,
and he's getting VERY close
Deems Davis # 406
Baffling / Plenum / Engine Stuff
http://deemsrv10.com/
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV10-List |
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