Today's Message Index:
----------------------
1. 08:10 AM - James Cowl (Dan Beadle)
2. 09:07 AM - Re: James Cowl (Blake Lewis)
3. 09:44 AM - Re: James Cowl (Mauri Morin)
4. 10:31 AM - Re: James Cowl (Dan Beadle)
5. 12:42 PM - Re: James Cowl (Paul Schattauer)
6. 04:03 PM - Re: James Cowl (gordon or marge)
7. 08:05 PM - James Cowl (Wlively)
8. 08:05 PM - [ Richard Dudley ] : New Email List Photo Share Available! (Email List Photo Shares)
Message 1
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--> RV8-List message posted by: "Dan Beadle" <Dan.Beadle@hq.InclineSoftworks.com>
I have heard great things about the James Cowl for RV8 from one lister.
I wonder if others have tried this and what the results are. It makes a
lot of sense to me. The claim is less drag > higher speed, very
believable. But are these results real?
I tried to order a finish kit from Van's and they poo-pooed the whole
notion. Specifically, I want to switch to:
- Grove Landing Gear
- James Cowl & Plenum
- James Fairings
- AC Prop
I am after light weight and speed without compromising the other specs
of the airplane. Weight up front to move CG back, allowing for CS
prop... Speed... Just because.
Message 2
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--> RV8-List message posted by: "Blake Lewis" <blake.lewis@gmail.com>
On 5/8/06, Dan Beadle <Dan.Beadle@hq.inclinesoftworks.com> wrote:
> --> RV8-List message posted by: "Dan Beadle" <Dan.Beadle@hq.InclineSoftworks.com>
>
> I tried to order a finish kit from Van's and they poo-pooed the whole
> notion. Specifically, I want to switch to:
>
How did Van's "poo-poo" the idea?
Blake C. Lewis
Message 3
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--> RV8-List message posted by: "Mauri Morin" <maurv8@bresnan.net>
Message 4
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--> RV8-List message posted by: "Dan Beadle" <Dan.Beadle@hq.InclineSoftworks.com>
Basically, they sent a couple emails indicating that 46 more HP would be
required to get the speed improvements that James claims. I agree that
you can go faster with more HP but generally faster is from less drag -
one of the reasons that the tandem RVs are so fast.
Dan
-----Original Message-----
From: owner-rv8-list-server@matronics.com
[mailto:owner-rv8-list-server@matronics.com] On Behalf Of Blake Lewis
Sent: Monday, May 08, 2006 9:06 AM
Subject: Re: RV8-List: James Cowl
--> RV8-List message posted by: "Blake Lewis" <blake.lewis@gmail.com>
On 5/8/06, Dan Beadle <Dan.Beadle@hq.inclinesoftworks.com> wrote:
> --> RV8-List message posted by: "Dan Beadle"
<Dan.Beadle@hq.InclineSoftworks.com>
>
> I tried to order a finish kit from Van's and they poo-pooed the whole
> notion. Specifically, I want to switch to:
>
How did Van's "poo-poo" the idea?
Blake C. Lewis
Message 5
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--> RV8-List message posted by: "Paul Schattauer" <chasm711@msn.com>
Dan
The increase in speed with the James cowl is difficult to quantify. The 8s
around here with it report little if any difference. You will get a bigger
increase with power/prop improvements. If you like the look of the James
cowl by all means go for it. The stock setup built properly is a good
system, only a little less efficient than the plenum system. The idea of
increased cooling efficiency and reduced cooling drag is a good one but
there are a lot of unrealistic expectations out there. Build it light and
build it straight (hard not to) and you will have a great performing
airplane. Also every time you change something the law of unintended
consequences comes in play and you will add months, even years to the
project. On the other hand the way you want it is the perfect way to build
an airplane. Have fun.
Paul Schattauer
RV 8 808PS
(the red "8"you click to get into Vans web site)
>From: "Dan Beadle" <Dan.Beadle@hq.inclinesoftworks.com>
>To: <rv8-list@matronics.com>
>Subject: RV8-List: James Cowl
>Date: Mon, 8 May 2006 08:07:31 -0700
>
>--> RV8-List message posted by: "Dan Beadle"
><Dan.Beadle@hq.InclineSoftworks.com>
>
>I have heard great things about the James Cowl for RV8 from one lister.
>I wonder if others have tried this and what the results are. It makes a
>lot of sense to me. The claim is less drag > higher speed, very
>believable. But are these results real?
>
>
>I tried to order a finish kit from Van's and they poo-pooed the whole
>notion. Specifically, I want to switch to:
>
>
>- Grove Landing Gear
>
>- James Cowl & Plenum
>
>- James Fairings
>
>- AC Prop
>
>
>I am after light weight and speed without compromising the other specs
>of the airplane. Weight up front to move CG back, allowing for CS
>prop... Speed... Just because.
>
>
Message 6
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--> RV8-List message posted by: "gordon or marge" <gcomfo@tc3net.com>
Subject: RV8-List: James Cowl
--> RV8-List message posted by: "Dan Beadle"
--> <Dan.Beadle@hq.InclineSoftworks.com>
I have heard great things about the James Cowl for RV8 from one lister. I
wonder if others have tried this and what the results are. It makes a lot
of sense to me. The claim is less drag > higher speed, very believable.
But are these results real?
I tried to order a finish kit from Van's and they poo-pooed the whole
notion. Specifically, I want to switch to:
- Grove Landing Gear
- James Cowl & Plenum
- James Fairings
- AC Prop
Dan: The answer to the question regarding lower drag with the James cowl is
another question: Compared to what? The advantage possible with the James
lies mainly in a few areas. The big one is air leaks in the cooling system.
Another is the placement of the inlets away from the boundary layer around
the spinner. Another is perhaps some improvement in parasite drag due to
its shape. With regard to air leaks a plenum connected to the inlets with
the radiused rings and flexible conduit may be better than a baffle system.
I say "may" because a plenum must be well sealed in order to do its best.
The use of piano hinges to assemble the cover, unless a seal can be
incorporated, will compromise the system. Other fastening methods could be
better. A well executed baffle system will do as well. At the inlets, the
James cowl may be better but it may be difficult to measure the difference
between it and a good conventional system. With regard to the inlet
location, the area between the inlets and the spinner can be clumsy and the
advantage is hard to estimate. With regard to inlet shape, Raspet used
round inlets because they were easy to calculate, not because he thought
round had significant advantages. When A.J.Smith and Len Niemi built the
AJ-2 they used a conventional system and the engine was well cooled and the
bird was fast. Could it have been faster with a plenum? Perhaps, but not
by much. When Commander Aircraft redesigned their bird Smith did the
cooling system and he did not choose round inlets. That is not to say that
round inlets are bad, only that other shapes are not bad either. Not many
formula one airplanes use round inlets. One other possible plus for the
James cowl is its effect on power available. If the in line inlet, filter,
servo combination is better than the snorkle, that could be part of the
apparent difference. Your guess is as good as mine but just looking at it
it seem reasonable that the James might be better.On the RV-8 with the angle
valve 360 or 390 engine, the extra prop extension needed with the James
moves the CG forward. An Aerocomposites or MT prop is helpful when weighed
against a Hartzell. A plenum must be disassembled to service the top of the
engine, a minor inconvenience.
I know of no systematic testing program that has addressed these issues. It
would be difficult to compare the James cowl with Van's stock cowl because
of the prop extension difference. It might be easier with the 180hp because
both use the inline carb air intake but the need to use a different prop
would mask the results. With the 200hp fwf, the combustion air intake
differences and prop setforward difference would be a chore to overcome. It
is not simple and I've only touched on some of it. As a practical matter it
comes down to your personal preference. What you believe is better, your
choice of aesthetic qualities, operational convenience and your willingness
to experiment will influence your decision. As for me, my -8 will have an
AC prop, no plenum and Van's stock 200hp cowl modified with a inline engine
air/filtering system. Maybe I'll regret it. Only time will tell.
Gordon Comfort
N363GC
Message 7
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--> RV8-List message posted by: "Wlively" <wlively@gvtc.com>
>From what I hear, the James cowl is alot of work to get it fitted correctly.
That is why, if I am going to spend alot of work I might as well do it all
myself. I am going to build my own plenum and modify the cowl inlets.
>From the NASA paper the major reason for round inlets, is that round gave
the same amount of air with different anglkes of relative wind and a round
shape is the most area for least space. So I agree, nothing majic about
being round. Plenum systems, if done right, are more effecient than stock.
Just look at Dave Anders RV-4. But you must think about not only the air
going it, but the air going out. The inlet/outlet ratios and configurations
are important.
For good reading see this website.
http://www.n91cz.com/cooling/webCowlrep.htm
An Aero eng and Lancair builder flew stock, then built a new cowl and plenum
and reports his findings. He also took alot of pressure test data inside the
cowl and there is a link to the NASA paper on engine cooling design.
Good Luck,
Wade Lively
-8, finishing
________________________________________________
webmail.gvtc.com
Message 8
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| Subject: | [ Richard Dudley ] : New Email List Photo Share Available! |
--> RV8-List message posted by: Email List Photo Shares <pictures@matronics.com>
A new Email List Photo Share is available:
Poster: Richard Dudley <rhdudley1@bellsouth.net>
Lists: AeroElectric-List,RV3-List,RV4-List,RV6-List,RV7-List,RV8-List,RV9-List,RV10-List,RV-List
Subject: Groundpower jack
http://www.matronics.com/photoshare/rhdudley1@bellsouth.net.05.08.2006/index.html
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