REFLECTOR: Reflector Digest, Vol 33, Issue 61 Exhaust coating
Brian Michalk
michalk at awpi.com
Mon Feb 19 09:39:20 CST 2007
Jet Hot did mine as well.
They are used to doing hot rods, so they want to make it shiny and red,
chrome or some other splashy color. I told the tech I did not care what
it looked like. I wanted the absolute minimum of temperature transfer.
He said ceramic, flat black inside and out. I had my intake manifolds
and exhaust done. It wasn't very expensive as far as aviation goes.
I had another engine start yesterday. After one run, I inspected the
exhaust sometime between three and five minutes after shutdown and the
exhaust was already cool enough to touch.
Mark Riley wrote:
> Try having your exhausts ceramic coated. They lowered my CHT's and as an
> additional benefit, keep them from rusting. I had mine done by Jet Hot.
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of reflector-request at tvbf.org
> Sent: Sunday, February 18, 2007 7:18 PM
> To: reflector at tvbf.org
> Subject: Reflector Digest, Vol 33, Issue 61
>
> Send Reflector mailing list submissions to
> reflector at tvbf.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://www.tvbf.org/mailman/listinfo/reflector
> or, via email, send a message with subject or body 'help' to
> reflector-request at tvbf.org
>
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>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Reflector digest..."
>
>
> Today's Topics:
>
> 1. Exhaust wrap. was updraft cooling (Scott Derrick)
> 2. Exhaust wrap. was updraft cooling (Scott Derrick)
> 3. Re: Updraft cooling (Unterreiner)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 18 Feb 2007 17:15:37 -0500 (EST)
> From: "Scott Derrick" <scott at tnstaafl.net>
> Subject: REFLECTOR: Exhaust wrap. was updraft cooling
> To: velocity at davebiz.com, "Velocity Aircraft Owners and Builders list"
> <reflector at tvbf.org>
> Message-ID: <49344.75.6.245.222.1171836937.squirrel at tnstaafl.net>
> Content-Type: text/plain;charset=iso-8859-1
>
> I tried that when I had updraft cooling. I was having major cooling
> issues so I wrapped the exhaust. Had no effect at all on my cooling. I've
> been told it also can cause your pipes to corrode faster over time.
>
> The fix for my cooling woes was to get absolutely fanatical about tight
> baffling, temps dropped 75 degrees.
>
> Scott
>
>
>> Chuck, I think you're right. My A&P suggested that I wrap the exhaust
>> pipes with insulating fabric (appears to be made from fiberglass) on my
>> updraft system. This should keep the heat more contained in the pipes
>> and exhausting outside of the plane. I have not flown yet since
>> wrapping so I can't tell you how much it affects temps.
>>
>> Chuck Jensen wrote:
>>
>>> I've not seen the layout of an updraft cooling system, but does the
>>> air get preheated from passing by the exhaust pipes before it every
>>> gets to the cylinder heads? If it does, that would greatly increase
>>> the volume of air required because of the reduced delta T across the
>>> heads. By comparison the top NACAs provide clean, cool air directly
>>> to the CHs. Too simple--I must be missing something?
>>>
>>> Chuck Jensen
>>> * *
>>> -----Original Message-----
>>> *From:* reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]
>>> *On Behalf Of *John Dibble
>>> *Sent:* Saturday, February 17, 2007 2:41 PM
>>> *To:* Velocity Aircraft Owners and Builders list
>>> *Subject:* Re: REFLECTOR: updraft cooling
>>>
>>> I think the amount of air going past the cylinders will determine the
>>> degree of cooling, so it's a matter of making the NACA or armpit scoop
>>> and ducts big enough for sufficient air.
>>>
>>> John
>>>
>>> Ron Brown wrote:
>>>
>>>
>>>> And, the downdraft NACA cooling for some unexplainable reason, runs
>>>> about 40 degrees cooler than the updraft cooling. Mark Machado
>>>> converted what is now the factory trainer from updraft to downdraft
>>>> and says the heads ran 30-40 degrees cooler. My 173 Elite RG runs
>>>> 360-370 max on a long climb out and 320-340 degrees during a 2600
>>>> rpm/155 kt cruise. I highly recommend the NACA cooling system.
>>>>
>>> ------------------------------------------------------------------------
>>>
>>> _______________________________________________
>>> To change your email address, visit
>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>
>>> Visit the gallery! www.tvbf.org/gallery
>>> user:pw = tvbf:jamaicangoose
>>> Check new archives: www.tvbf.org/pipermail
>>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>>>
>> --
>> Dave Philipsen
>> Velocity STD-FG
>> N83DP
>>
>>
>> _______________________________________________
>> To change your email address, visit
>> http://www.tvbf.org/mailman/listinfo/reflector
>>
>> Visit the gallery! www.tvbf.org/gallery
>> user:pw = tvbf:jamaicangoose
>> Check new archives: www.tvbf.org/pipermail
>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>>
>>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Sun, 18 Feb 2007 17:15:42 -0500 (EST)
> From: "Scott Derrick" <scott at tnstaafl.net>
> Subject: REFLECTOR: Exhaust wrap. was updraft cooling
> To: velocity at davebiz.com, "Velocity Aircraft Owners and Builders list"
> <reflector at tvbf.org>
> Message-ID: <49346.75.6.245.222.1171836942.squirrel at tnstaafl.net>
> Content-Type: text/plain;charset=iso-8859-1
>
> I tried that when I had updraft cooling. I was having major cooling
> issues so I wrapped the exhaust. Had no effect at all on my cooling. I've
> been told it also can cause your pipes to corrode faster over time.
>
> The fix for my cooling woes was to get absolutely fanatical about tight
> baffling, temps dropped 75 degrees.
>
> Scott
>
>
>> Chuck, I think you're right. My A&P suggested that I wrap the exhaust
>> pipes with insulating fabric (appears to be made from fiberglass) on my
>> updraft system. This should keep the heat more contained in the pipes
>> and exhausting outside of the plane. I have not flown yet since
>> wrapping so I can't tell you how much it affects temps.
>>
>> Chuck Jensen wrote:
>>
>>> I've not seen the layout of an updraft cooling system, but does the
>>> air get preheated from passing by the exhaust pipes before it every
>>> gets to the cylinder heads? If it does, that would greatly increase
>>> the volume of air required because of the reduced delta T across the
>>> heads. By comparison the top NACAs provide clean, cool air directly
>>> to the CHs. Too simple--I must be missing something?
>>>
>>> Chuck Jensen
>>> * *
>>> -----Original Message-----
>>> *From:* reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]
>>> *On Behalf Of *John Dibble
>>> *Sent:* Saturday, February 17, 2007 2:41 PM
>>> *To:* Velocity Aircraft Owners and Builders list
>>> *Subject:* Re: REFLECTOR: updraft cooling
>>>
>>> I think the amount of air going past the cylinders will determine the
>>> degree of cooling, so it's a matter of making the NACA or armpit scoop
>>> and ducts big enough for sufficient air.
>>>
>>> John
>>>
>>> Ron Brown wrote:
>>>
>>>
>>>> And, the downdraft NACA cooling for some unexplainable reason, runs
>>>> about 40 degrees cooler than the updraft cooling. Mark Machado
>>>> converted what is now the factory trainer from updraft to downdraft
>>>> and says the heads ran 30-40 degrees cooler. My 173 Elite RG runs
>>>> 360-370 max on a long climb out and 320-340 degrees during a 2600
>>>> rpm/155 kt cruise. I highly recommend the NACA cooling system.
>>>>
>>> ------------------------------------------------------------------------
>>>
>>> _______________________________________________
>>> To change your email address, visit
>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>
>>> Visit the gallery! www.tvbf.org/gallery
>>> user:pw = tvbf:jamaicangoose
>>> Check new archives: www.tvbf.org/pipermail
>>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>>>
>> --
>> Dave Philipsen
>> Velocity STD-FG
>> N83DP
>>
>>
>> _______________________________________________
>> To change your email address, visit
>> http://www.tvbf.org/mailman/listinfo/reflector
>>
>> Visit the gallery! www.tvbf.org/gallery
>> user:pw = tvbf:jamaicangoose
>> Check new archives: www.tvbf.org/pipermail
>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>>
>>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Sun, 18 Feb 2007 19:17:55 -0500
> From: "Unterreiner" <naomi at yadtel.net>
> Subject: Re: REFLECTOR: Updraft cooling
> To: <reflector at tvbf.org>
> Message-ID: <003a01c753bb$67b196f0$0a01a8c0 at DELL280IMAGE2>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> Dave,
>
> Let me know if you come up with any ingenious ideas on your engine
> cooling. My email is naomi at yadtel.net.
>
> Goodluck,
> Dean Unterreiner
>
> ----- Original Message -----
> From: <reflector-request at tvbf.org>
> To: <reflector at tvbf.org>
> Sent: Sunday, February 18, 2007 11:30 AM
> Subject: Reflector Digest, Vol 33, Issue 52
>
>
>
>> Send Reflector mailing list submissions to
>> reflector at tvbf.org
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>> http://www.tvbf.org/mailman/listinfo/reflector
>> or, via email, send a message with subject or body 'help' to
>> reflector-request at tvbf.org
>>
>> You can reach the person managing the list at
>> reflector-owner at tvbf.org
>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of Reflector digest..."
>>
>>
>> Today's Topics:
>>
>> 1. Re: Updraft cooling (John Dibble)
>> 2. Re: CBs and fuses (John Tvedte)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Sun, 18 Feb 2007 10:27:36 -0600
>> From: John Dibble <aminetech at bluefrog.com>
>> Subject: Re: REFLECTOR: Updraft cooling
>> To: velocity at davebiz.com, Velocity Aircraft Owners and Builders list
>> <reflector at tvbf.org>
>> Message-ID: <45D87E78.9A701FF2 at bluefrog.com>
>> Content-Type: text/plain; charset=us-ascii
>>
>> According to my Franklin engine manual, the measured CHT will be 50 C (90
>> F) higher with a spark
>> plug probe, located on the bottom plug, compared to a bayonet probe,
>> located on the top of the
>> cylinder. Maybe the temperature difference is due to the direction of air
>>
>
>
>> flow. I have downdraft
>> cooling. The air should be much warmer after passing the cylinder.
>> Therefore the temperature at
>> the bottom of my cylinders should be higher than at the top. If the
>> bayonet probe is used and
>> cooling is switched from updraft to downdraft, a lower CHT may not
>> necessarily mean the overall
>> cylinder temp is lower. Just a thought.
>>
>> John
>>
>> Dave Philipsen wrote:
>>
>>
>>> Dean,
>>>
>>> I'm in the same boat (plane) as you. I bought a Velocity that was built
>>> by someone else and it has updraft cooling too. But, I think that's the
>>> way they all were originally. The NACA scoops were introduced as
>>> standard a little later. I'm in the midst of working on ways to cool it
>>> more efficiently. At least this forum will help perhaps by providing us
>>> with some ideas.
>>>
>>> Unterreiner wrote:
>>>
>>>> I have an IO-360 in my Velocity with updraft cooling. The guy who built
>>>>
>
>
>>>> the
>>>> plane went to alot of trouble to get it to cool properly in cruise, and
>>>>
>
>
>>>> it
>>>> still needs to be modified so it will cool better during takeoff. Also,
>>>>
>
>
>>>> the
>>>> Lycoming engines are designed to be cooled from the top down. I wish
>>>> the guy
>>>> who built my plane would have used the NACA plenum system. It's alot
>>>> simpler, cools the engine the way it's supposed to be cooled and is
>>>> less
>>>> prone to develop cooling problems.
>>>>
>>>> Dean Unterreiner
>>>> ----- Original Message -----
>>>> From: <reflector-request at tvbf.org>
>>>> To: <reflector at tvbf.org>
>>>> Sent: Saturday, February 17, 2007 5:52 PM
>>>> Subject: Reflector Digest, Vol 33, Issue 47
>>>>
>>>>
>>>>
>>>>
>>>>> Send Reflector mailing list submissions to
>>>>> reflector at tvbf.org
>>>>>
>>>>> To subscribe or unsubscribe via the World Wide Web, visit
>>>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>>> or, via email, send a message with subject or body 'help' to
>>>>> reflector-request at tvbf.org
>>>>>
>>>>> You can reach the person managing the list at
>>>>> reflector-owner at tvbf.org
>>>>>
>>>>> When replying, please edit your Subject line so it is more specific
>>>>> than "Re: Contents of Reflector digest..."
>>>>>
>>>>>
>>>>> Today's Topics:
>>>>>
>>>>> 1. Re: updraft cooling (Scott Derrick)
>>>>> 2. Re: updraft cooling (John Dibble)
>>>>> 3. Re: updraft cooling (Douglas Holub)
>>>>> 4. Re: updraft vs sidedraft vs updraft cooling (gpoole)
>>>>> 5. Re: updraft cooling (Al Gietzen)
>>>>>
>>>>>
>>>>> ----------------------------------------------------------------------
>>>>>
>>>>> Message: 1
>>>>> Date: Sat, 17 Feb 2007 15:57:56 -0500 (EST)
>>>>> From: "Scott Derrick" <scott at tnstaafl.net>
>>>>> Subject: Re: REFLECTOR: updraft cooling
>>>>> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>>>>> Message-ID: <43917.63.164.47.227.1171745876.squirrel at tnstaafl.net>
>>>>> Content-Type: text/plain;charset=iso-8859-1
>>>>>
>>>>> Doug,
>>>>>
>>>>> I had updraft on my IO360 and it worked fine. I had to run LOP in the
>>>>> summer(I did all the time anyway) to keep the engine cool enough.
>>>>> There
>>>>> were times when I stopped for gas and during the following departure
>>>>> climbout I would have to level off at an intermediate altitude for
>>>>> awhile
>>>>> to get the oil temps back down below 230.
>>>>>
>>>>> Installing my 520 I conferred with Velocity(ScottB and Brendon) and
>>>>> was
>>>>> advised I would need to use downdraft as they had never successfully
>>>>> seen
>>>>> an updraft system work for the big six cylinder engines. So I did
>>>>> the
>>>>> conversion.
>>>>>
>>>>> I thought that using NACA intakes would "theoretically" be more drag
>>>>> effecient ?
>>>>>
>>>>> Scott
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> I can understand why Burt Rutan and Nat Puffer are proponents of
>>>>>> updraft
>>>>>> cooling. From an engineering point of view, it has a lot going for
>>>>>> it.
>>>>>> You
>>>>>> need more cooling when the airplane is climbing. If the cooling
>>>>>> intake is
>>>>>> below the wing, the pressure is higher during a climb so you
>>>>>> automatically
>>>>>> get more cooling during a climb. Similarly, it would be nice if
>>>>>> cooling
>>>>>> was minimized during descent. The pressure is reduced under the wing
>>>>>> during descent, and so there is less cooling to the engine. Also,
>>>>>> you've
>>>>>> got convection working with you instead of against you with an
>>>>>> updraft
>>>>>> system.
>>>>>>
>>>>>> That all adds up to more drag with down draft cooling, because the
>>>>>> NACA
>>>>>> scoops have to be large enough so that there is adequate cooling
>>>>>> during
>>>>>> climb out, when the pressure at the NACAs is at its minimum.
>>>>>>
>>>>>> But the down draft is a lot simpler to implement, and that's probably
>>>>>> going to be the deciding factor for me.
>>>>>>
>>>>>> Doug Holub_______________________________________________
>>>>>> To change your email address, visit
>>>>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>>>>
>>>>>> Visit the gallery! www.tvbf.org/gallery
>>>>>> user:pw = tvbf:jamaicangoose
>>>>>> Check new archives: www.tvbf.org/pipermail
>>>>>> Check old archives:
>>>>>> http://www.tvbf.org/archives/velocity/maillist.html
>>>>>>
>>>>>>
>>>>> ------------------------------
>>>>>
>>>>> Message: 2
>>>>> Date: Sat, 17 Feb 2007 15:04:56 -0600
>>>>> From: John Dibble <aminetech at bluefrog.com>
>>>>> Subject: Re: REFLECTOR: updraft cooling
>>>>> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
>>>>> Message-ID: <45D76DF8.5468770B at bluefrog.com>
>>>>> Content-Type: text/plain; charset="us-ascii"
>>>>>
>>>>> I assume that updraft simply refers to the intake air coming from
>>>>> below
>>>>> as opposed to downdraft where the air comes from the NACAs above. I
>>>>> think the way it passes the engine is the same. It would be
>>>>> inefficient
>>>>> to pass the air past the exhaust pipes first.
>>>>>
>>>>> John
>>>>>
>>>>> Chuck Jensen wrote:
>>>>>
>>>>>
>>>>>
>>>>>> I've not seen the layout of an updraft cooling system, but does the
>>>>>> air get preheated from passing by the exhaust pipes before it every
>>>>>> gets to the cylinder heads? If it does, that would greatly increase
>>>>>> the volume of air required because of the reduced delta T across the
>>>>>> heads. By comparison the top NACAs provide clean, cool air directly
>>>>>> to the CHs. Too simple--I must be missing something?
>>>>>> Chuck Jensen
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]
>>>>>> On Behalf Of John Dibble
>>>>>> Sent: Saturday, February 17, 2007 2:41 PM
>>>>>> To: Velocity Aircraft Owners and Builders list
>>>>>> Subject: Re: REFLECTOR: updraft cooling
>>>>>>
>>>>>> I think the amount of air going past the cylinders will determine the
>>>>>> degree of cooling, so it's a matter of making the NACA or armpit
>>>>>> scoop
>>>>>> and ducts big enough for sufficient air.
>>>>>>
>>>>>> John
>>>>>>
>>>>>> Ron Brown wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>> And, the downdraft NACA cooling for some unexplainable reason, runs
>>>>>>> about 40 degrees cooler than the updraft cooling. Mark Machado
>>>>>>> converted what is now the factory trainer from updraft to downdraft
>>>>>>> and says the heads ran 30-40 degrees cooler. My 173 Elite RG runs
>>>>>>> 360-370 max on a long climb out and 320-340 degrees during a 2600
>>>>>>> rpm/155 kt cruise. I highly recommend the NACA cooling system.
>>>>>>>
>>>>>>>
>>>>>> ----------------------------------------------------------------
>>>>>> _______________________________________________
>>>>>> To change your email address, visit
>>>>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>>>>
>>>>>> Visit the gallery! www.tvbf.org/gallery
>>>>>> user:pw = tvbf:jamaicangoose
>>>>>> Check new archives: www.tvbf.org/pipermail
>>>>>> Check old archives:
>>>>>> http://www.tvbf.org/archives/velocity/maillist.html
>>>>>>
>>>>>>
>>>>>>
>>>>> -------------- next part --------------
>>>>> An HTML attachment was scrubbed...
>>>>> URL:
>>>>>
>>>>>
> http://www.tvbf.org/mailman/private/reflector/attachments/20070217/daaba585/
> attachment.htm
>
>>>>> ------------------------------
>>>>>
>>>>> Message: 3
>>>>> Date: Sat, 17 Feb 2007 16:13:01 -0600
>>>>> From: "Douglas Holub" <doug.holub at tx.rr.com>
>>>>> Subject: Re: REFLECTOR: updraft cooling
>>>>> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>>>>> Message-ID: <007e01c752e0$ca67f130$6a01a8c0 at Workshop>
>>>>> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>>>>> reply-type=original
>>>>>
>>>>> "I thought that using NACA intakes would 'theoretically' be more drag
>>>>> effecient ?"
>>>>> -------------------------------------------------------------------
>>>>> I was just comparing updraft to downdraft. It looks like I could put
>>>>> one
>>>>> big
>>>>> NACA underneath the rear seat. I was thinking of using that spot for
>>>>> ram
>>>>> air, though.
>>>>>
>>>>> I'm a little confused about the benefits of a NACA scoop. I need to
>>>>> read
>>>>> up
>>>>> on them some more. I think that if the cowl lip were extended up a
>>>>> little
>>>>> to
>>>>> catch the air it might be more efficient than the NACA scoops. But
>>>>> even
>>>>> if
>>>>> it were more efficient, you would be making it a little harder for air
>>>>>
>
>
>>>>> to
>>>>> flow to the propeller because the cowl would be getting a little
>>>>> taller.
>>>>> But
>>>>> then, you lose some head room in the back seats with the NACAs.
>>>>> Decisions,
>>>>> decisions.
>>>>>
>>>>> Doug Holub
>>>>>
>>>>> ----- Original Message -----
>>>>> From: "Scott Derrick" <scott at tnstaafl.net>
>>>>> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>>>>> Sent: Saturday, February 17, 2007 2:57 PM
>>>>> Subject: Re: REFLECTOR: updraft cooling
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> Doug,
>>>>>>
>>>>>> I had updraft on my IO360 and it worked fine. I had to run LOP in the
>>>>>> summer(I did all the time anyway) to keep the engine cool enough.
>>>>>> There
>>>>>> were times when I stopped for gas and during the following departure
>>>>>> climbout I would have to level off at an intermediate altitude for
>>>>>> awhile
>>>>>> to get the oil temps back down below 230.
>>>>>>
>>>>>> Installing my 520 I conferred with Velocity(ScottB and Brendon) and
>>>>>> was
>>>>>> advised I would need to use downdraft as they had never successfully
>>>>>> seen
>>>>>> an updraft system work for the big six cylinder engines. So I did
>>>>>> the
>>>>>> conversion.
>>>>>>
>>>>>> I thought that using NACA intakes would "theoretically" be more drag
>>>>>> effecient ?
>>>>>>
>>>>>> Scott
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>> I can understand why Burt Rutan and Nat Puffer are proponents of
>>>>>>> updraft
>>>>>>> cooling. From an engineering point of view, it has a lot going for
>>>>>>> it.
>>>>>>> You
>>>>>>> need more cooling when the airplane is climbing. If the cooling
>>>>>>> intake
>>>>>>> is
>>>>>>> below the wing, the pressure is higher during a climb so you
>>>>>>> automatically
>>>>>>> get more cooling during a climb. Similarly, it would be nice if
>>>>>>> cooling
>>>>>>> was minimized during descent. The pressure is reduced under the wing
>>>>>>> during descent, and so there is less cooling to the engine. Also,
>>>>>>> you've
>>>>>>> got convection working with you instead of against you with an
>>>>>>> updraft
>>>>>>> system.
>>>>>>>
>>>>>>> That all adds up to more drag with down draft cooling, because the
>>>>>>> NACA
>>>>>>> scoops have to be large enough so that there is adequate cooling
>>>>>>> during
>>>>>>> climb out, when the pressure at the NACAs is at its minimum.
>>>>>>>
>>>>>>> But the down draft is a lot simpler to implement, and that's
>>>>>>> probably
>>>>>>> going to be the deciding factor for me.
>>>>>>>
>>>>>>> Doug Holub_______________________________________________
>>>>>>> To change your email address, visit
>>>>>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>>>>>
>>>>>>> Visit the gallery! www.tvbf.org/gallery
>>>>>>> user:pw = tvbf:jamaicangoose
>>>>>>> Check new archives: www.tvbf.org/pipermail
>>>>>>> Check old archives:
>>>>>>> http://www.tvbf.org/archives/velocity/maillist.html
>>>>>>>
>>>>>>>
>>>>>> _______________________________________________
>>>>>> To change your email address, visit
>>>>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>>>>
>>>>>> Visit the gallery! www.tvbf.org/gallery
>>>>>> user:pw = tvbf:jamaicangoose
>>>>>> Check new archives: www.tvbf.org/pipermail
>>>>>> Check old archives:
>>>>>> http://www.tvbf.org/archives/velocity/maillist.html
>>>>>>
>>>>>>
>>>>>>
>>>>> ------------------------------
>>>>>
>>>>> Message: 4
>>>>> Date: Sun, 18 Feb 2007 09:29:29 +1100
>>>>> From: "gpoole" <gpoole at zeta.org.au>
>>>>> Subject: Re: REFLECTOR: updraft vs sidedraft vs updraft cooling
>>>>> To: "'Velocity Aircraft Owners and Builders list'"
>>>>> <reflector at tvbf.org>
>>>>> Message-ID: <00b801c752e3$1725de40$4deb64cb at gregb97b7132b4>
>>>>> Content-Type: text/plain; charset="windows-1250"
>>>>>
>>>>> I have been making the same deliberations as Doug for quite some time.
>>>>> There are compromises with every option ..sigh! Scoops vs NACA
>>>>> ducts...
>>>>>
>>>>> If pinching air before the prop with a scoop on the belly is
>>>>> considered to
>>>>> affect prop efficiency then perhaps (surely?) Al G's & several other's
>>>>> approach of putting radiators in the wing is the way to go. I like
>>>>> the
>>>>> idea
>>>>> of being able to tailor the amount of air to the radiators to balance
>>>>> the
>>>>> compromise between drag and amount of cooling required by having
>>>>> variable
>>>>> inlets. Only problem is that the air needs to do several sharp turns
>>>>> to
>>>>> get
>>>>> to the cylinder heads....which would should slow it down
>>>>> considerably....
>>>>>
>>>>> Would be interested in this thread continuing to see what others
>>>>> think....
>>>>>
>>>>> Greg in Sydney.
>>>>>
>>>>> gregpoole at saaachapter11.com
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]
>>>>> On
>>>>> Behalf Of Douglas Holub
>>>>> Sent: Sunday, 18 February 2007 9:13 AM
>>>>> To: Velocity Aircraft Owners and Builders list
>>>>> Subject: Re: REFLECTOR: updraft cooling
>>>>>
>>>>> "I thought that using NACA intakes would 'theoretically' be more drag
>>>>> effecient ?"
>>>>> -------------------------------------------------------------------
>>>>> I was just comparing updraft to downdraft. It looks like I could put
>>>>> one
>>>>> big
>>>>>
>>>>> NACA underneath the rear seat. I was thinking of using that spot for
>>>>> ram
>>>>> air, though.
>>>>>
>>>>> I'm a little confused about the benefits of a NACA scoop. I need to
>>>>> read
>>>>> up
>>>>>
>>>>> on them some more. I think that if the cowl lip were extended up a
>>>>> little
>>>>> to
>>>>>
>>>>> catch the air it might be more efficient than the NACA scoops. But
>>>>> even
>>>>> if
>>>>> it were more efficient, you would be making it a little harder for air
>>>>>
>
>
>>>>> to
>>>>> flow to the propeller because the cowl would be getting a little
>>>>> taller.
>>>>> But
>>>>>
>>>>> then, you lose some head room in the back seats with the NACAs.
>>>>> Decisions,
>>>>> decisions.
>>>>>
>>>>> Doug Holub
>>>>>
>>>>> ----- Original Message -----
>>>>> From: "Scott Derrick" <scott at tnstaafl.net>
>>>>> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>>>>> Sent: Saturday, February 17, 2007 2:57 PM
>>>>> Subject: Re: REFLECTOR: updraft cooling
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> Doug,
>>>>>>
>>>>>> I had updraft on my IO360 and it worked fine. I had to run LOP in the
>>>>>> summer(I did all the time anyway) to keep the engine cool enough.
>>>>>> There
>>>>>> were times when I stopped for gas and during the following departure
>>>>>> climbout I would have to level off at an intermediate altitude for
>>>>>> awhile
>>>>>> to get the oil temps back down below 230.
>>>>>>
>>>>>> Installing my 520 I conferred with Velocity(ScottB and Brendon) and
>>>>>> was
>>>>>> advised I would need to use downdraft as they had never successfully
>>>>>> seen
>>>>>> an updraft system work for the big six cylinder engines. So I did
>>>>>> the
>>>>>> conversion.
>>>>>>
>>>>>> I thought that using NACA intakes would "theoretically" be more drag
>>>>>> effecient ?
>>>>>>
>>>>>> Scott
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>> I can understand why Burt Rutan and Nat Puffer are proponents of
>>>>>>> updraft
>>>>>>> cooling. From an engineering point of view, it has a lot going for
>>>>>>> it.
>>>>>>> You
>>>>>>> need more cooling when the airplane is climbing. If the cooling
>>>>>>> intake
>>>>>>> is
>>>>>>> below the wing, the pressure is higher during a climb so you
>>>>>>> automatically
>>>>>>> get more cooling during a climb. Similarly, it would be nice if
>>>>>>> cooling
>>>>>>> was minimized during descent. The pressure is reduced under the wing
>>>>>>> during descent, and so there is less cooling to the engine. Also,
>>>>>>> you've
>>>>>>> got convection working with you instead of against you with an
>>>>>>> updraft
>>>>>>> system.
>>>>>>>
>>>>>>> That all adds up to more drag with down draft cooling, because the
>>>>>>> NACA
>>>>>>> scoops have to be large enough so that there is adequate cooling
>>>>>>> during
>>>>>>> climb out, when the pressure at the NACAs is at its minimum.
>>>>>>>
>>>>>>> But the down draft is a lot simpler to implement, and that's
>>>>>>> probably
>>>>>>> going to be the deciding factor for me.
>>>>>>>
>>>>>>> Doug Holub_______________________________________________
>>>>>>> To change your email address, visit
>>>>>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>>>>>
>>>>>>> Visit the gallery! www.tvbf.org/gallery
>>>>>>> user:pw = tvbf:jamaicangoose
>>>>>>> Check new archives: www.tvbf.org/pipermail
>>>>>>> Check old archives:
>>>>>>> http://www.tvbf.org/archives/velocity/maillist.html
>>>>>>>
>>>>>>>
>>>>>> _______________________________________________
>>>>>> To change your email address, visit
>>>>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>>>>
>>>>>> Visit the gallery! www.tvbf.org/gallery
>>>>>> user:pw = tvbf:jamaicangoose
>>>>>> Check new archives: www.tvbf.org/pipermail
>>>>>> Check old archives:
>>>>>> http://www.tvbf.org/archives/velocity/maillist.html
>>>>>>
>>>>>>
>>>>>>
>>>>> _______________________________________________
>>>>> To change your email address, visit
>>>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>>>
>>>>> Visit the gallery! www.tvbf.org/gallery
>>>>> user:pw = tvbf:jamaicangoose
>>>>> Check new archives: www.tvbf.org/pipermail
>>>>> Check old archives:
>>>>> http://www.tvbf.org/archives/velocity/maillist.html
>>>>>
>>>>> --
>>>>> No virus found in this incoming message.
>>>>> Checked by AVG Free Edition.
>>>>> Version: 7.1.412 / Virus Database: 268.18.1/690 - Release Date:
>>>>> 16/02/2007
>>>>>
>>>>>
>>>>> --
>>>>> No virus found in this outgoing message.
>>>>> Checked by AVG Free Edition.
>>>>> Version: 7.1.412 / Virus Database: 268.18.1/690 - Release Date:
>>>>> 16/02/2007
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> ------------------------------
>>>>>
>>>>> Message: 5
>>>>> Date: Sat, 17 Feb 2007 14:52:30 -0800
>>>>> From: "Al Gietzen" <ALVentures at cox.net>
>>>>> Subject: Re: REFLECTOR: updraft cooling
>>>>> To: "'Velocity Aircraft Owners and Builders list'"
>>>>> <reflector at tvbf.org>
>>>>> Message-ID: <000001c752e6$4ecd94c0$6400a8c0 at BigAl>
>>>>> Content-Type: text/plain; charset="us-ascii"
>>>>>
>>>>> Subject: REFLECTOR: updraft cooling
>>>>>
>>>>>
>>>>>
>>>>> I can understand why Burt Rutan and Nat Puffer are proponents of
>>>>> updraft
>>>>> cooling. From an engineering point of view, it has a lot going for it.
>>>>>
>
>
>>>>> You
>>>>> need more cooling when the airplane is climbing. If the cooling intake
>>>>>
>
>
>>>>> is
>>>>> below the wing, the pressure is higher during a climb so you
>>>>> automatically
>>>>> get more cooling during a climb. Similarly, it would be nice if
>>>>> cooling
>>>>> was
>>>>> minimized during descent. The pressure is reduced under the wing
>>>>> during
>>>>> descent, and so there is less cooling to the engine. Also, you've got
>>>>> convection working with you instead of against you with an updraft
>>>>> system.
>>>>>
>>>>> Doug;
>>>>>
>>>>>
>>>>>
>>>>> I'd think that both climbing and descending are high AOA, and would
>>>>> have
>>>>> similar air pressure under the wing; and given the strake
>>>>> configuration,
>>>>> it
>>>>> is not clear that there is increased pressure during climb. I also
>>>>> think
>>>>> that the main reason for difficulties with the stock armpit scoops and
>>>>> updraft is they are poorly designed scoops. Need to have ever
>>>>> increasing
>>>>> x-section after the entrance, and possilby placing them a bit further
>>>>> outboard from the strake/fuselage intersection would be helpful.
>>>>>
>>>>>
>>>>>
>>>>> I have an 'armpit' scoop for my radiator which is very effective.
>>>>>
>>>>>
>>>>>
>>>>> But the down draft is a lot simpler to implement, and that's probably
>>>>> going
>>>>> to be the deciding factor for me.
>>>>>
>>>>>
>>>>>
>>>>> And since it seems to work well, why not? The amount of natural
>>>>> convection
>>>>> driving force is likely overcome by a few knots of forward speed.
>>>>>
>>>>> Al
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Doug Holub
>>>>>
>>>>> -------------- next part --------------
>>>>> An HTML attachment was scrubbed...
>>>>> URL:
>>>>>
>>>>>
> http://www.tvbf.org/mailman/private/reflector/attachments/20070217/bff4b314/
> attachment.html
>
>>>>> ------------------------------
>>>>>
>>>>> _______________________________________________
>>>>> Visit the gallery! tvbf:jamaicangoose
>>>>>
>>>>> End of Reflector Digest, Vol 33, Issue 47
>>>>> *****************************************
>>>>>
>>>>>
>>>> _______________________________________________
>>>> To change your email address, visit
>>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>>
>>>> Visit the gallery! www.tvbf.org/gallery
>>>> user:pw = tvbf:jamaicangoose
>>>> Check new archives: www.tvbf.org/pipermail
>>>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>>>>
>>>>
>>>>
>>>>
>>> --
>>> Dave Philipsen
>>> Velocity STD-FG
>>> N83DP
>>>
>>> _______________________________________________
>>> To change your email address, visit
>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>
>>> Visit the gallery! www.tvbf.org/gallery
>>> user:pw = tvbf:jamaicangoose
>>> Check new archives: www.tvbf.org/pipermail
>>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>>>
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Sun, 18 Feb 2007 10:29:52 -0600
>> From: "John Tvedte" <johnt at comp-sol.com>
>> Subject: Re: REFLECTOR: CBs and fuses
>> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>> Message-ID:
>> <182DCED417B03E45BDB40B10169D1D020A95EF at exchange-2003.comp-sol.com>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Personally I think CB's are the proper choice - I think it makes more
>> sense for the Pilot to choose to reset or NOT reset a circuit.
>>
>> John
>>
>> ________________________________
>>
>> From: reflector-bounces at tvbf.org on behalf of John Overman
>> Sent: Sun 2/18/2007 10:16 AM
>> To: bbradburry at allvantage.com; reflector at tvbf.org
>> Subject: Re: REFLECTOR: CBs and fuses
>>
>>
>>
>> Hi Bill;
>> I ordered them from Mouser Electronics, they are
>> also available from Digi-Key and Allied Electronics
>> Supply. They are called PTC resettable fuses and are
>> manufactured by Bournes, Raychem Tyco, and Little
>> Fuse. There is a good explaination about how the work
>> on Raychem and most of the other's websites. Here's a
>> rough explaination of how the work. They contain
>> "tracks" of carbon which makes the connection. When
>> they get hot the tracks "flow out" so they are no
>> longer conductive thus breaking the circuit. If the
>> device causing the overload is shut off, the fuse
>> quickly cools and the tracks reform thus "resetting"
>> the fuse. If the device is not turned off the circuit
>> remains open. I will install them in "Proto-Board" and
>> hard wire them to terminal blocks (Buchanan terminal
>> blocks) also from Mouser 12 terminals 2.5"wide for
>> $6.03, mounted along the edge of the board.
>> I ordered the RayChem fuses because they have them
>> rated up to 14 amps and they can be paralleled which
>> would give you a 28 Amp fuse. 0.5 amp fuses are $0.54
>> ea. and 14amp fuses are $1.34 ea.
>> They are reported to trip faster, and more
>> accurately, than a breaker and cool to reset faster.
>> Greg Richter (Blue Mountain Avionics) uses them in his
>> "Power Board".
>> I hope this isn't more information than you wanted,
>> and that it helps.
>> John Overman
>> Velocity RG N711VE (reserved)
>>
>>
>> --- Bill Bradburry <bbradburry at allvantage.com> wrote:
>>
>>
>>> Hi John.
>>> Where will you get the resettable fuses? Several
>>> folks on the list have
>>> suggested that I install CBs in my flight critical
>>> areas. I am thinking
>>> that the resettable fuses might solve the problem...
>>> What do you think?
>>>
>>> Bill Bradburry (Lancair Legacy FG / Renesis)
>>>
>>>
>>> Subject:
>>> Re: [FlyRotary] CBs and fuses
>>> From:
>>> John Overman <mooneydryver at yahoo.com>
>>> Date:
>>> Sat, 17 Feb 2007 16:15:29 -0800 (PST)
>>>
>>> Al or anyone, speaking of fuses, I'm about to order
>>> PTC resettable fuses in my Velocity, and haven't
>>> been
>>> able to find any load values for the stock mazda
>>> coils, the fuel injectors, the EC2 or the EM2, Al as
>>> I
>>> recall you are using LS1 coils not Mazda but I
>>> haven't
>>> come up with anything. I even looked in the RX7
>>> manual
>>> to see what size fuse Mazda used. It just says the
>>> fuses are listed under the cap.
>>> John Overman
>>> Velocity RG N711VE
>>> (reserved)
>>>
>>>
>> _______________________________________________
>> To change your email address, visit
>> http://www.tvbf.org/mailman/listinfo/reflector
>>
>> Visit the gallery! www.tvbf.org/gallery
>> user:pw Check new archives: www.tvbf.org/pipermail
>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>>
>>
>> -------------- next part --------------
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>> Url :
>>
>>
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> attachment.bin
>
>> ------------------------------
>>
>> _______________________________________________
>> Visit the gallery! tvbf:jamaicangoose
>>
>> End of Reflector Digest, Vol 33, Issue 52
>> *****************************************
>>
>
>
>
> ------------------------------
>
> _______________________________________________
> Visit the gallery! tvbf:jamaicangoose
>
> End of Reflector Digest, Vol 33, Issue 61
> *****************************************
>
>
> _______________________________________________
> To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector
>
> Visit the gallery! www.tvbf.org/gallery
> user:pw = tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
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