But why put a scoop if it doesn't work?

Thanks,
Chris

---- Original message ----
>Date: Thu, 22 Aug 2002 19:43:49 -0400
>From: "G. Matthew Bulley" <gmbulley@BULLEY-HEWLETT.COM>
>Subject: Re: Custom Scoop Update - Should you care!
>To: vanagon@GERRY.VANAGON.COM
>
>You'll note that all other forms of racing (GTP, IMSA,
etc.) that have a
>body structure that allows for NACA ducting, uses it for
intake, engine
>cooling as well as brake cooling. The body style of the
formula one
>makes a NACA duct for the mid-mounted engine impossible.
>
>
>Developing business and guiding change since 1996,
>
>G. Matthew Bulley
>Bulley-Hewlett
>Marketing & Communications
>Business: www.bulley-hewlett.com
>AIM = IExplain4u
>Phone: +1.919.658.1278
>
>
>-----Original Message-----
>From: Clive Smith [mailto:clive.harman-smith@ntlworld.com]
>Sent: Thursday, August 22, 2002 7:31 PM
>To: G. Matthew Bulley; vanagon@GERRY.VANAGON.COM
>Subject: Re: Re: Custom Scoop Update - Should you care!
>
>Funny then, that Formula One racing cars (technologically
the ultimate
>racing cars) mostly have a scoop above the drivers head (to
collect the
>coolest air possible of course)
>
>No the problem resolves down to matching the inlet area
with the duct
>cross
>sectional area and max mass flow rate.
>Also the inlet nacelle's shape and radius are important.
>After all, what do you see at the front of the biggest air
breathing
>engines
>made - aircraft gas turbines. Not flush intakes - but then
they ARE big
>suckers!
>
>Clive
>
>----- Original Message -----
>From: "G. Matthew Bulley" <gmbulley@BULLEY-HEWLETT.COM>
>To: <vanagon@GERRY.VANAGON.COM>
>Sent: Friday, August 23, 2002 12:16 AM
>Subject: Re: Custom Scoop Update - Should you care!
>
>
>> Yes, "NACA flush intake" is the proper term or NACA duct.
>>
>> Too early for a "senior moment" so call it overwork, and
lack of
>sleep.
>> Jpeg attached  over simplifies/exaggerates the concept,
but here is
>the
>> essence of the problem with scoops.
>>
>> The leading (extended edge) of the scoop sets up a
pressure wave
>> directly in front of itself. Wherever I read about this
(lost to the
>> sands of time) talked about the speeds at which this
pressure wave was
>> worst, with different types of ducts. Needless to say, it
was bad at
>ALL
>> vehicle speeds except about 5 mph, where scoops had a
narrow
>advantage.
>>
>>
>> Worse, that pressure wave is compressed by the air
passing by the
>> outboard of the scoop into the area you would THINK has a
massive air
>> stream (directly in front of the scoop), where the
turbulent pressure
>> wave acts like a big fat cork.
>>
>> So make scoops if you want, but notice that VW gradually
got rid of
>the
>> scoops, and so did all other manufacturers. NACA ducts
work. Scoops
>> don't.
>>
>> Developing business and guiding change since 1996,
>>
>> G. Matthew Bulley
>> Bulley-Hewlett
>> Marketing & Communications
>> Business: www.bulley-hewlett.com
>> AIM = IExplain4u
>> Phone: +1.919.658.1278
>>
>>
>> -----Original Message-----
>> From: Vanagon Mailing List
[mailto:vanagon@GERRY.VANAGON.COM] On
>Behalf
>> Of Clive Smith
>> Sent: Thursday, August 22, 2002 6:16 PM
>> To: vanagon@GERRY.VANAGON.COM
>> Subject: Re: Custom Scoop Update - Should you care!
>>
>> Mathew,
>>
>> Whilst some of your reasoning makes a little sense, what
doesn't is
>the
>> term
>> 'laminar flow ducts'. Theres nothing specific about the
boundary layer
>> at
>> the
>> back of a vanagon that would entice an aerodynamicist to
use that
>term.
>>
>> What these 'flush' vents might be called are just that -
flush vents
>or
>> maybe -
>> at a push - NACA flush intakes, although they're not
exactly designed
>as
>> a
>> true NACA slotted intakes.
>>
>> I think what you're trying to point out is this: if the
flow rate
>drawn
>> off
>> by the
>> sink (the induction system) can't handle the flow rate
into the Mark's
>> scoop
>> then there will be spillage, which in itself will
increase drag.
>>
>> However,
>> > Maybe I've missed out by being off list.
>> which was a few messages a month or so ago, where Mark
was advocating
>> these
>> for enhacing the flow through either an oil cooler or an
turbo
>> intercooler
>> positioned
>> down where the duct shaft exhausts. Provided the other
side of the
>> cooling
>> matrix
>> is in a relatively low pressure region, they could indeed
provide a
>good
>> flow rate, as
>> a cooler could pass more air than an engine intake
(unless we're
>talking
>> a
>> RR Merlin
>> at full chat).
>>
>> If other sources refer to flush inlets as laminar flow
ducts, I'd be
>> pleased
>> to know
>> the source, as the relevance of what at the back (and
even less so the
>> front) of a
>> 15 ft object travelling at 60mph is a thin boundary is
pretty
>> irrelevant.
>> Boundary layer
>> state and overall flow attachment/separation, although
interrelated,
>are
>> quite different
>> things - a turbulent boundary layer for instance does not
imply
>> separated
>> flow, and can
>> actually prevent it (e.g. the well-known golf ball
dimpling example).
>> Additionally, flow rate into and through a duct as large
as the
>vanagons
>> at
>> the speeds its
>> likely to be going, would if anything be greater for a
trubulent b.l.,
>> following on from the
>> golf-ball reasoning - it wouldn't separate as easily
around the bends
>> (which
>> create adverse
>> pressure gradients on their inside radius).
>>
>> Hope this helps, not that I am a fan of scoops; maybe
Mark should make
>> it
>> clear again that
>> they were designed for an oil/intercooler installation
and that any
>> dynamic
>> pressure head gain
>> for an inlet system, however well designed, is negligible
until about
>> 120
>> mph (about 1%).
>>
>> Clive
>> '88 Syncro Transporter
>>
>> ----- Original Message -----
>> From: "G. Matthew Bulley" <gmbulley@BULLEY-HEWLETT.COM>
>> To: <vanagon@GERRY.VANAGON.COM>
>> Sent: Thursday, August 22, 2002 3:27 AM
>> Subject: Re: Custom Scoop Update - Should you care!
>>
>>
>> > Scoops? For what?
>> > Maybe I've missed out by being off list.
>> >
>> > I pray these are not some sort of DIY 'improvement' the
laminar flow
>> > induction duct at the rear of our vans. Boston Bob and
I have gone a
>> > round or two on p-mail in the past over
his "ears" 'improvements'
>the
>> > well-designed VW ducts.
>> >
>> > Long and short, if these 'scoops have to do with
airflow into the
>rear
>> > ducts, think again. Then look at *all* modern sports
cars and
>realize
>> > that "scoops" have gone the way of the Holley 4-barrel.
Scoops
>create
>> a
>> > pressure wave right in front of the induction hole,
making their
>> intake
>> > negligible. Measure your before and after head temp to
confirm.
>> >
>> > Laminar flow ducts, (like on the Vanagon, Porsche
Boxster, MR2,
>Saleen
>> > SR & S7, Honda S2000, and a host of other cars) are
multifold more
>> > efficient, and are only ruined by 'scoops' and 'ears'.
>> >
>> > So what are these "scoops" all about?
>> >
>> > Developing business and guiding change since 1996,
>> >
>> > G. Matthew Bulley
>> > Bulley-Hewlett
>> > Marketing & Communications
>> > Business: www.bulley-hewlett.com
>> > AIM = IExplain4u
>> > Phone: +1.919.658.1278
>> >
>> >
>> > -----Original Message-----
>> > From: Vanagon Mailing List
[mailto:vanagon@GERRY.VANAGON.COM] On
>> Behalf
>> > Of Mark Thoma
>> > Sent: Thursday, August 22, 2002 12:06 AM
>> > To: vanagon@GERRY.VANAGON.COM
>> > Subject: Custom Scoop Update - Should you care!
>> >
>> > The scoop on the scoops,
>> > After patching up my screw ups on one of the scoop
molds, I took
>them
>> > both (right and left) to a boat repair guy here in the
Cleveland
>area
>> > who does a lot of fiberglass gelcoat kinda stuff and he
said "well
>> they
>> > look pretty darn nice, but... (like peewee herman
said, "Everybody's
>> got
>> > a big but") you need to polish and buff the molds now,
then spray in
>> > release agent, then a layer of gelcoat then 4 layers of
fiberglass
>> cloth
>> > and the fiberglass cloth needs to go on top of the
gelcoat while the
>> > gelcoat is still tacky."
>> > Me, feeling an assault on my wallet coming on,
said "How much?"
>> > He said "$100 bucks for the pair of finished scoops."
To which I
>said,
>> > "Go for it."
>> > Then he said, "But you can sell these things to all of
your Vanagon
>> > buddies and make all your time and effort pay off."
And I said
>"Well
>> > why wouldn't I just make all the subsequent scoops
myself, after all
>I
>> > have the molds?"
>> > To which he replied, "You could but the molds have to
be polished
>and
>> > buffed between each use, and that takes a lot of work,
and then you
>> have
>> > to shoot the gelcoat, lay the 4 layers of fiberglass
cloth, etc."
>> > So I said "Well how much for each set of scoops?"
>> > And he said "$100 per pair no matter how many pairs we
make."
>> > And I said, "But how much could I sell them for?"
>> > And he said, "Something this nice, $175 for the pair."
>> > And I said, "Those cheap bast----I mean those
economically minded
>> > fellows on the Vanagon list will never pay that much."
>> > And he said, "Okay tell them $150 for the pair and
you'll pay the
>> > shipping. And if you don't sell one pair what do you
care, you still
>> > have the scoops you wanted in the first place?"
>> > And I said, "MAKES SENSE TO ME!"
>> > So that's the long and short of it.  I should have the
first pair
>back
>> > in a week.  I'll take some pictures of them mounted on
the van and
>> > you'll know how to reach me should you want a set.
>> > Mark
>> >
>> > Mark Thoma