REFLECTOR: Updraft cooling
Unterreiner
naomi at yadtel.net
Sun Feb 18 18:17:55 CST 2007
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
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>
> 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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>> >>
>> >> 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:
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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
>> >>>> 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.
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>> >> 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)
>>
>
>
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