REFLECTOR: Exhaust wrap

Unterreiner naomi at yadtel.net
Sun Feb 18 18:33:14 CST 2007


   I was considering trying exhaust wraps, but heard they didn't make any 
difference and had negative effects on the pipes. The race car accessory 
shops sell a loose fitting exhaust pipe heat shield which may work just as 
well and would be better on the pipes and allow for easier inspection. Let 
us know if the wraps make any difference.

Dean Unterreiner
----- Original Message ----- 
From: <reflector-request at tvbf.org>
To: <reflector at tvbf.org>
Sent: Sunday, February 18, 2007 7:18 PM
Subject: Reflector Digest, Vol 33, Issue 61


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> 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
>>>
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>>
>> --
>> Dave Philipsen
>> Velocity STD-FG
>> N83DP
>>
>>
>> _______________________________________________
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>> http://www.tvbf.org/mailman/listinfo/reflector
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>>
>
>
>
> ------------------------------
>
> 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
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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. 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
>>> >>
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>>> >> 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 --------------
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>>> >>
>>> >> ------------------------------
>>> >>
>>> >> 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
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>>> >>>> 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
>>> >>>
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>>> >>> http://www.tvbf.org/archives/velocity/maillist.html
>>> >>>
>>> >>>
>>> >> _______________________________________________
>>> >> To change your email address, visit
>>> >> http://www.tvbf.org/mailman/listinfo/reflector
>>> >>
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>>> >>
>>> >> --
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>>> >> Checked by AVG Free Edition.
>>> >> Version: 7.1.412 / Virus Database: 268.18.1/690 - Release Date:
>>> >> 16/02/2007
>>> >>
>>> >>
>>> >> --
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>>> >> 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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>>
>> ------------------------------
>>
>> _______________________________________________
>> 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
> ***************************************** 



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