Today's Message Index:
----------------------
1. 04:17 AM - Re: Crossover exhaust. (Kevin Horton)
2. 05:39 AM - Re: TruTrak ADI (Larry Pardue)
3. 08:27 AM - Re: TruTrak ADI (Sherri & Paul Richardson)
4. 09:15 AM - space above cooling plenum (George Inman)
5. 09:29 AM - Re: space above cooling plenum (Alex Peterson)
6. 09:42 AM - Senenich prop wanted. (Steve Kiekover)
7. 12:43 PM - RV: Crossover exhaust (best exhaust & where heat comes from) ()
8. 01:58 PM - Re: Senenich prop wanted. (Darrell Reiley)
9. 03:52 PM - Fw: Vetterman Exhaust (LarryRobertHelming)
10. 09:43 PM - Paint scheme question (Doug Medema)
11. 10:44 PM - Hangar space @ CNO available (Tailgummer@aol.com)
12. 10:47 PM - Re: Paint scheme question (Stein Bruch)
Message 1
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| Subject: | Re: Crossover exhaust. |
--> RV-List message posted by: Kevin Horton <khorton01@rogers.com>
On 20 Nov 2005, at 01:06, DEAN PSIROPOULOS wrote:
> --> RV-List message posted by: "DEAN PSIROPOULOS"
> <dean.psiropoulos@verizon.net>
>
> What wives-tail or urban legend says the exhaust
> has to crossover? Is this another thing we builders do just because
> production aircraft did it and because everyone else does it? Larry
> Vetterman why aren't you building NON-crossover exhaust?
CAFE Foundation testing suggests that a well tuned 4 into 1 exhaust
system would probably make more power than a cross-over system. Note
that they did not actually measure horsepower. They put pressure
probes in the intake and exhaust system, and measured the intake and
exhaust ports and looked at what the pressure values were when the
valves were open.
http://www.cafefoundation.org/aprs/EPG%20PART%20IV.pdf
They describe the theory behind a cross-over design on page 6 of the
pdf file. The conclusions on the last two pages are worth reading.
There are more details on how they measured the pressures here:
http://www.cafefoundation.org/aprs/epg.pdf
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://www.kilohotel.com/rv8
Message 2
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--> RV-List message posted by: "Larry Pardue" <n5lp@warpdriveonline.com>
> --> RV-List message posted by: "Ed Holyoke" <bicyclop@pacbell.net>
>
> Howdy Larry,
>
> GPS antennas can be had here (and I'm sure other places too):
>
> http://www.rst-engr.com/rst/catalog/gps_antenna.html
>
> or you could cut 'em open like Dan did to get rid of the magnet.
>
> Please post follow ups on flying the ADI.
Excellent tip on the RST link. I wonder if the connector on the ADI antenna
is one of the ones listed. It is tiny, something like 3 mm diameter and one
I haven't seen before. Even if RST will sell the proper antenna it is a
pity that one should have to buy another antenna. When I saw the magnet on
this aircraft antenna and old phrase involving a boar hog came to mind.
I probably won't post follow ups as this instrument is not in my airplane
and I won't get a chance to fly it that often.
Regards,
Larry Pardue
Carlsbad, NM
RV-6 N441LP Flying
http://n5lp.net
Message 3
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--> RV-List message posted by: "Sherri & Paul Richardson" <prichar@mail.win.org>
We were able to take our magnet out by positioning the antenna with magnet
on a steel beam and then prying the antenna off of it. Works very well right
next to the compass now.
Paul Richardson
106RV with Trutrak ADI
> Time: 08:36:35 PM PST US
> From: "Larry Pardue" <n5lp@warpdriveonline.com>
> Subject: RV-List: TruTrak ADI
>
........
> That real downer is that this instrument uses, like the XM antenna in my
> Garmin 396, a very magnetic GPS antenna. This is completely inappropriate
> in an aluminum airplane and makes it very difficult to mount the antenna
> in
> a position that does not direly affect the magnetic compass. These
> companies badly need to find a supplier without magnets, for the GA
> market.
>
> By the way, this instrument is a killer substitute for a turn coordinator.
>
> Larry Pardue
> Carlsbad, NM
>
> RV-6 N441LP Flying
> http://n5lp.net
Message 4
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| Subject: | space above cooling plenum |
--> RV-List message posted by: "George Inman" <ghinman@mts.net>
I am making a fiberglass cooling plenum and am trying to decide how much
spce to provide between the upper cowl and the top of the plenum.
Right now it is at least 1/4" everywhere, except at cyl. #1 which is
pretty tight. I'm sanding down a foam mold to do the lay-up, so I can
sand it further and create more space. For those of you who have made
plenums, can you advise me if 1/4" is enough clearance?
--
Tom Sargent, RV-6A, baffles.
TOM;
The following is a quote from the
installation guide
for van's baffle kit.
STEP I I - BAFFLE TO COWL, GAP CLEARANCE TRIM:
Trim for baffle to upper cowl, gap clearance. Gap should be 3/8" min.
1/2" max. To prevent cowl chafing, cutting the airseal fabric or section
blowout. The engine cowl is attached rigidly to the airframe while the
engine is free to move around quite a bit on the shock mounts
from "G" loads and during start up and shut down.
For this reason, accurate clearance is important.
.
George Inman
Message 5
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| Subject: | space above cooling plenum |
--> RV-List message posted by: "Alex Peterson" <alexpeterson@earthlink.net>
> --> RV-List message posted by: "George Inman" <ghinman@mts.net>
>
> I am making a fiberglass cooling plenum and am trying to
> decide how much
> spce to provide between the upper cowl and the top of the plenum.
> Right now it is at least 1/4" everywhere, except at cyl. #1
> which is pretty tight. I'm sanding down a foam mold to do
> the lay-up, so I can sand it further and create more space.
> For those of you who have made plenums, can you advise me if
> 1/4" is enough clearance?
> --
> Tom Sargent, RV-6A, baffles.
Tom, I don't have a plenum, but I'd sure think 1/4" would be asking for
trouble, especially if it is towards the outboard top of a cylinder. The
engine rotates about its fore/aft axis a lot more than one can imagine, when
you shut down or start up. I know also that my alternator pulley rubs from
time to time, and it is probably 3/8" from the cowl. That would be more
from up/down motion, such as g loads.
Watch someone start their RV with the cowl off sometime, for example, after
they change oil, and you will be amazed.
Alex Peterson
RV6-A N66AP 691 hours
Maple Grove, MN
Message 6
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| Subject: | Senenich prop wanted. |
--> RV-List message posted by: "Steve Kiekover" <stneki@hotmail.com>
Wanted Sensenich prop for RV-7A with O-360. Please email me or call
616-402-0038 ask for Steve
Message 7
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| Subject: | RV: Crossover exhaust (best exhaust & where heat comes from) |
--> RV-List message posted by: <gmcjetpilot@yahoo.com>
Dear Dean:
Good question but the exhaust pipes near the sump
have nothing to do with oil temp and the "Y" exhaust
pipe is the worst type you can have for making HP.
(I'LL EXPLAIN BELOW)
>From: "DEAN PSIROPOULOS" ><dean.psiropoulos@verizon.net>
>Subject: RV-List: Crossover exhaust.
>
>Question on exhaust:
>
>Parallel valve Lycoming 4 cylinder engine. Is
>there a GOOD reason the front two pipes have
>to cross over before they go out the cowling?
>Everyone says that Lycomings have to have an
>oil cooler because the oil runs hot. Gee I
>wonder why...two hot exhaust pipes run right
>past the front of the oil sump and dump gobs of
>heat into the oil (in addition to the rear
>cylinders heating up the sides of the sump)!!!
The Exhaust is not heating the sump and oil.
The valves are heating the oil. The process or
byproduct of combustion is (mechanical work/power
and heat), LOTS OF HEAT. The valves are the hottest
part and cooled by oil. Those drain tubes the run
from the head to the sump are full of very very hot
oil from cooling the valves. The oil temp off the valves
is 20F-25F hotter than what you read on the oil
temp gauge! Dont worry about the exhaust. The
sump is giving off heat not absorbing it. If the exhaust
is heating the oil it is worth 1 degree F. If you where
worried you could bond insulation on the sump but
think you would find you would increase oil temp.
The pipes would have to transfer their temp thru
convection or radiant. EGT is say 1400F near the
port flange, but by the time it makes it down further
it mixes with air and has given heat off and is less
than 1000F. The radiant heat 6" away is not that
great. There is lots of air blowing around in the lower
cowl also. THE BIGGEST PEOBLEM IS THE
EXHAUST is HEATING THE INTAKE TUBES. THIS
is WHERE YOU SHOULD WORRY ABOUT exhaust
heat. Off the topic, but true.
>So why not trash this exhaust pipe configuration
>and go to a simple 2 into 1 set up on each side of
>the engine? Just bring the two pipes together off
>the same side and dump it out the cowling without
>crossing over in front of the oil pan. A Lancair
>360 builder I know built his own exhaust like this
>from Aircraft Spruce parts. He says the crossover
>setup actually creates back pressure that robs
>engine power. Airplane isn't flying yet but I certainly
>see his logic in doing it. Another Q200 builder did
>the same thing with his 0-200 Continental engine
>and says there has been a noticeable difference in
>under-cowl temps (and no engine performance
>degradation). I can't believe this hasn't come up
>before, anybody know the answer? What wives-tail
>or urban legend says the exhaust has to crossover?
The "Y" exhaust is the worst. This in not opinion
this is fact born out by flight test and dyno runs.
Your buddies do not know what or how a Lycoming
fires and how exhaust work. Because the firing order
is 1-3 than 2-4 (meaning the two cylinders on one
side fire right after each other. You are trying to
pump two cylinders into one collector at one time).
The "Y" is simple and easy to make, BUT the worst
exhaust system you can make. Tell your buddies they
would be better off with 4 separate pipes. Really
4-separate pipes are not bad and really better than a
"Y" pipe. Vetterman makes these 4into4's. A "Y" pipe
is easy and works but it adds nothing. However factory
exhaust on Pipers and Cessnas are worse, so if you
want to do that fine but you may be loosing 15-20 HP
over the the best exhaust (WHICH IS NOT A CROSS
OVER). Also I doubt the "Y" pipe will lower oil temp.
In fact if you properly install a proper SW cooler
(Stewart Warner/South Wind not a clone cooler) you
will not have a oil temp problem.
>Is this another thing we builders do just
>because production aircraft did it and because
>everyone else does it? Larry Vetterman why
>aren't you building NON-crossover exhaust?
Because the 2 into 1 "Y" is crap. He does make
the 4-into-4. Look exhaust always has some
back-pressure during the middle later stages of
the exhaust cycle. In this part of cycle 4 inch
straight pipes stub pipes sticking right out the
side of the cowl would be best. However not
practical and The REAL magic is SCAVIGING
(which stubs have none). You want the exhaust
port to see negative pressure just before it closes.
This is the point the intake is also open at the
same time (called overlap). This promotes the
incoming fuel air mixture entering the cylinder,
in other words there is no backpressure at the
intake port at the start of the intake cycle. You
want the cylinder to be totally evacuated of exhaust
and even a little suck or scavenge at the start of
the intake valve opening. You also want a little
scavenging at the the EVO (exhaust valve opening).
The 4-into-1 does this well. The down side is you
need 19-30 inches of collector to optimize the
4-into-1 effect. However even a short 10" collector
will provide free HP, at least over any other
exhaust and will provide more even power between
cylinders.
(read the caf foundation 3-part reports on the web
cafefoundation.org, and write EAA that they should
support and publish CF articles.) BTW cross over is
not that great due to odd length pipe lengths. It thus
produces uneven power from the different cylinders.
The hand down winner is 4-into-1. Tied for second
is 4 into 4 and cross over. A distant last place is
a "Y" pipe.
>Dean Psiropoulos
Install your Vetterman as is now and go fly. You could
consider ceramic coating but DON'T TAPE THEM IN
HEAT WRAP, it will crack the pipe. Vettterman does
not like the ceramic but it is gaining favor. IF you want
the best performance exhaust sell the vetterman and
get a 4-into-1 from aircraftexhaust systems in MN.
(You have a "A" model RV and its hard to make a true
tuned tube length 4into1 with a nose gear in the way,
but AE can do it if you want. Tell them RV7 George
sent you.) http://www.aircraftexhaust.net/
DON'T let your buddies talk you into Y pipes and you
will have no oil temp problems if you use a SW cooler.
The pipes are not the problem. If any one argues that
the "Y" pipe does not loose HP have them read the
Cafe Reports, it is obvious what the best is.
PS: Consider ceramic coating inside AND outside the
pipes. You cannot coat the pipe where the heat muff.
In fact you should not coat the entire length of the pipe
withthe heat muff, but the other pipes can be coated
from exhaust flange to the aft end or logical slip joint.
I do not NOT recommend leaving just a band of pipe
un-coated where the heat muff. The discontinuity in the
middle of a pipe could cause a crack (due to thermal
stress).
George
---------------------------------
Message 8
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| Subject: | Re: Senenich prop wanted. |
--> RV-List message posted by: Darrell Reiley <lifeofreiley2003@yahoo.com>
I believe there's one for sale on Vansairforce.net..
do no archive
Steve Kiekover <stneki@hotmail.com> wrote:
--> RV-List message posted by: "Steve Kiekover"
Wanted Sensenich prop for RV-7A with O-360. Please email me or call
616-402-0038 ask for Steve
Darrell
RV7A - 622DR Reserved
---------------------------------
Message 9
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| Subject: | Fw: Vetterman Exhaust |
--> RV-List message posted by: "LarryRobertHelming" <lhelming@sigecom.net>
----- Original Message -----
From: Larry & Cathy Vetterman
Subject: Re: Vetterman Exhaust
My response is simple, The pipes do not heat up the oil. The mass airflow over
the cylinders and then over the pipes actually helps cool the engine,ie cylinder
temps which translates into oil temps. If you don't believe me, install the
exhaust wrap on the system (insulating blamket) that is becoming popular and
watch your cylinder temps and oil temps go up then watch your system melt off
of the engine. This wrap is supposed to keep the engine conmpartment ie. cowling
cool. Nope it does'nt work that way as it goes against all air cooled engine
theory. Why don't we connect two pipes into one one each side. It is so simple
to do it that way but because Lycoming chose to make the firing order 1324
on most 4 cylinder engines, that is front to back , placing a simple Y system
exhaust costs about 10 to 14 percent power. Because of this front to back
firing order, 2 exhaust pulses are try to occupy the same tubing area at the same
time. It creates a large and uneven back pressure on the cylinders and creates
what is know as a dirty charge on the intake stroke. This is just a simple
over view as it is more complex than stated. We didn't invent exhaust systems
for the 4 cylinder Lycoming but I have personally tried every comination that
we could get under the" Hood" and the crossover provides the best of the
four things desired. 1. Good power at 65 to 75 percent power. 2 Adequate room
for cabin and carb heat muffs. 3. By design, breakage is kept to a minimum
so you can fly to destinations far from home and not worry about exhaust problems.
4. the system is affordable-- there are systems out there that claim increased
power etc. at twice the cost. I have tried them and my RV just doesn't
seem to go any faster with other designs. So there it is. I invite any one
to call and discuss this with me. Regards Larry D. Veterman
----- Original Message -----
From: LarryRobertHelming
To: vetxaust@gwtc.net
Sent: Sunday, November 20, 2005 5:41 AM
Subject: Vetterman Exhaust
Picked this up and forwarded to you from the RV-List. I too am interested in
your response. Thanks. Indiana Larry in Evansville, RV7 Tip Up SunSeeker
((((((()))))))))--> RV-List message posted by: "DEAN PSIROPOULOS" <dean.psiropoulos@verizon.net>
Question on exhaust:
Parallel valve Lycoming 4 cylinder engine. Is there a GOOD reason the front
two pipes have to cross over before they go out the cowling? Everyone says
that Lycomings have to have an oil cooler because the oil runs hot. Gee I
wonder why...two hot exhaust pipes run right past the front of the oil sump
and dump gobs of heat into the oil (in addition to the rear cylinders
heating up the sides of the sump)!!! So why not trash this exhaust pipe
configuration and go to a simple 2 into 1 set up on each side of the engine?
Just bring the two pipes together off the same side and dump it out the
cowling without crossing over in front of the oil pan. A Lancair 360
builder I know built his own exhaust like this from Aircraft Spruce parts.
He says the crossover setup actually creates back pressure that robs engine
power. Airplane isn't flying yet but I certainly see his logic in doing it.
Another Q200 builder did the same thing with his 0-200 Continental engine
and says there has been a noticeable difference in under-cowl temps (and no
engine performance degradation). I can't believe this hasn't come up before,
anybody know the answer? What wives-tail or urban legend says the exhaust
has to crossover? Is this another thing we builders do just because
production aircraft did it and because everyone else does it? Larry
Vetterman why aren't you building NON-crossover exhaust?
Dean Psiropoulos
RV-6A N197DM
Installing exhaust
Message 10
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| Subject: | Paint scheme question |
--> RV-List message posted by: "Doug Medema" <doug.medema@comcast.net>
If you looked at my website after my previous post, you know
I'm seriously
contemplating painting my plane a dark blue (actually
Chevrolet Indigo Blue
like on my TrailBlazer.) I know a dark colored car can get
very hot inside
but am wondering if it makes much difference on an RV. We
have the clear
canopy and mine already has a black glareshield. The only
area in the cockpit
that would be affected is the area over the back of the
baggage compartment.
So, any of you that have dark paint on the top -- does your
cockpit get really
hot in the sun, or do you think it is about the same as a
lighter color?
Thanks,
Doug Medema
RV-6A N276DM down for 2nd condition inspection.
Message 11
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| Subject: | Hangar space @ CNO available |
--> RV-List message posted by: Tailgummer@aol.com
Hangar space @ CNO for an RV sized aircraft will be available immediately.
If interested please call me. John D'Onofrio Cell # (949)394-1910.
_Tailgummer@aol.com_ (mailto:Tailgummer@aol.com)
Message 12
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| Subject: | Paint scheme question |
--> RV-List message posted by: "Stein Bruch" <stein@steinair.com>
Hi Doug,
Go for the dark color - I like to see some color on RV's! My older RV6 is
Black on top and my "almost finished" new RV6 is entirely White. In all
reality not much difference at all when flying, and frankly not much
difference on the ground. In the hot sun, they both are hotter than heck
under that big piece of glass until you get moving, but once flying
everything is ok.
There's sure to be debate about the darker vs. light colors, but the reality
is that it really doesn't make much difference at all.
Just my 2 cents as usual!
Cheers,
Stein.
-----Original Message-----
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com]On Behalf Of Doug Medema
Subject: RV-List: Paint scheme question
--> RV-List message posted by: "Doug Medema" <doug.medema@comcast.net>
If you looked at my website after my previous post, you know
I'm seriously
contemplating painting my plane a dark blue (actually
Chevrolet Indigo Blue
like on my TrailBlazer.) I know a dark colored car can get
very hot inside
but am wondering if it makes much difference on an RV. We
have the clear
canopy and mine already has a black glareshield. The only
area in the cockpit
that would be affected is the area over the back of the
baggage compartment.
So, any of you that have dark paint on the top -- does your
cockpit get really
hot in the sun, or do you think it is about the same as a
lighter color?
Thanks,
Doug Medema
RV-6A N276DM down for 2nd condition inspection.
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