JS-1 Exhaust Vent

[sisu1a]

Gotta hand it to Johan Bosman on this one... look at pg 5 of this pdf:
http://www.streckenflug.at/news/js_communication_2010_07.pdf
Personally I think his take on the exhaust vent is simply ingenious.
The opening on that thing is immense and has got to allow much air to
pass, but flow is organized by that little louver/wing. Pure genius.

I may just be preoccupied on the subject right now since I'm in the
middle of making vented ASW-20 hatches (Mandl and Butler styles) for
the upcoming 20 gathering at Tehachapi. Pics to follow...

-Paul

[Bruno[_2_]]

Paul,
I am greatly looking forward to seeing your work at the upcoming 20
get together. I was talking to a few pilots I respect at the Region 9
Logan contest last week and mentioned your proposed vent and they said
that there will be a problem with the hatch being off to one side and
not centered. What do you think? Still count me in for trying one
out. :)

Bruno - B4

On Jul 25, 4:33*pm, sisu1a > wrote:
> Gotta hand it to Johan Bosman on this one... look at pg 5 of this pdf:http://www.streckenflug.at/news/js_communication_2010_07.pdf
> Personally I think his take on the exhaust vent is simply ingenious.
> The opening on that thing is immense and has got to allow much air to
> pass, but flow is organized by that little louver/wing. Pure genius.
>
> I may just be preoccupied on the subject right now since I'm in the
> middle of making vented ASW-20 hatches (Mandl and Butler styles) for
> the upcoming 20 gathering at Tehachapi. Pics to follow...
>
> -Paul

[Dave Nadler]

On Jul 25, 8:52*pm, Bruno > wrote:
> ... there will be a problem with the hatch being off to one side and
> not centered...

You mean, like the DG exit vents ?

[Darryl Ramm]

On Jul 25, 5:52*pm, Bruno > wrote:
> Paul,
> I am greatly looking forward to seeing your work at the upcoming 20
> get together. *I was talking to a few pilots I respect at the Region 9
> Logan contest last week and mentioned your proposed vent and they said
> that there will be a problem with the hatch being off to one side and
> not centered. *What do you think? *Still count me in for trying one
> out. *:)
>
> Bruno - B4
>
> On Jul 25, 4:33*pm, sisu1a > wrote:
>
> > Gotta hand it to Johan Bosman on this one... look at pg 5 of this pdf:http://www.streckenflug.at/news/js_communication_2010_07.pdf
> > Personally I think his take on the exhaust vent is simply ingenious.
> > The opening on that thing is immense and has got to allow much air to
> > pass, but flow is organized by that little louver/wing. Pure genius.
>
> > I may just be preoccupied on the subject right now since I'm in the
> > middle of making vented ASW-20 hatches (Mandl and Butler styles) for
> > the upcoming 20 gathering at Tehachapi. Pics to follow...
>
> > -Paul
>
>

Maybe equally impressive to the engineering of the JS1 exhaust vent is
the psychological-gamesmanship of emphasizing the performance
enhancement effects of this just prior to the 18m Worlds. Love it.

Darryl

[Tim Taylor]

On Jul 25, 4:33*pm, sisu1a > wrote:
> Gotta hand it to Johan Bosman on this one... look at pg 5 of this pdf:http://www.streckenflug.at/news/js_communication_2010_07.pdf
> Personally I think his take on the exhaust vent is simply ingenious.
> The opening on that thing is immense and has got to allow much air to
> pass, but flow is organized by that little louver/wing. Pure genius.
>
> I may just be preoccupied on the subject right now since I'm in the
> middle of making vented ASW-20 hatches (Mandl and Butler styles) for
> the upcoming 20 gathering at Tehachapi. Pics to follow...
>
> -Paul

I still think a reversed NACA duct will work better than the Butler
and much better than the Mandl. The Mandl throws the low speed air
out into the faster air stream. The JS design accelerates half the
air over the airfoil but what happens to the air under the airfoil?

[Brad[_2_]]

On Jul 25, 6:11*pm, Darryl Ramm > wrote:
> On Jul 25, 5:52*pm, Bruno > wrote:
>
>
>
>
>
> > Paul,
> > I am greatly looking forward to seeing your work at the upcoming 20
> > get together. *I was talking to a few pilots I respect at the Region 9
> > Logan contest last week and mentioned your proposed vent and they said
> > that there will be a problem with the hatch being off to one side and
> > not centered. *What do you think? *Still count me in for trying one
> > out. *:)
>
> > Bruno - B4
>
> > On Jul 25, 4:33*pm, sisu1a > wrote:
>
> > > Gotta hand it to Johan Bosman on this one... look at pg 5 of this pdf:http://www.streckenflug.at/news/js_communication_2010_07.pdf
> > > Personally I think his take on the exhaust vent is simply ingenious.
> > > The opening on that thing is immense and has got to allow much air to
> > > pass, but flow is organized by that little louver/wing. Pure genius.
>
> > > I may just be preoccupied on the subject right now since I'm in the
> > > middle of making vented ASW-20 hatches (Mandl and Butler styles) for
> > > the upcoming 20 gathering at Tehachapi. Pics to follow...
>
> > > -Paul
>
> Maybe equally impressive to the engineering of the JS1 exhaust vent is
> the psychological-gamesmanship of emphasizing the performance
> enhancement effects of this just prior to the 18m Worlds. Love it.
>
> Darryl

perhaps some will file the trailing edge of their wings to a knife
like edge...............no, wait, that's been done before!

[noel.wade]

On Jul 25, 9:54*pm, Tim Taylor > wrote:
>
> I still think a reversed NACA duct will work better than the Butler
> and much better than the Mandl. *The Mandl throws the low speed air
> out into the faster air stream. *The JS design accelerates half the
> air over the airfoil but what happens to the air under the airfoil?

All good points, but I have an even bigger question: What happens when
the cockpit air intakes are closed (say on a cold day or at high/cold
altitudes)? It seems to me that there would be an ideal extractor
position & size (or louver camber/AOA) for each particular air intake
position... You're looking for a balance in order to keep the fuselage
airflow from being unnecessarily disturbed at one end or the other,
right? I mean, with a tight canopy seal and closed intakes isn't your
fixed-size extractor going to be starved for airflow once the cockpit
pressure reaches its minimum, and that is going to in turn wind up
disturbing the airflow over the extractor itself?

--Noel

[Grider Pirate]

On Jul 26, 12:02*am, "noel.wade" > wrote:
> On Jul 25, 9:54*pm, Tim Taylor > wrote:
>
>
>
> > I still think a reversed NACA duct will work better than the Butler
> > and much better than the Mandl. *The Mandl throws the low speed air
> > out into the faster air stream. *The JS design accelerates half the
> > air over the airfoil but what happens to the air under the airfoil?
>
> All good points, but I have an even bigger question: What happens when
> the cockpit air intakes are closed (say on a cold day or at high/cold
> altitudes)? *It seems to me that there would be an ideal extractor
> position & size (or louver camber/AOA) for each particular air intake
> position... You're looking for a balance in order to keep the fuselage
> airflow from being unnecessarily disturbed at one end or the other,
> right? *I mean, with a tight canopy seal and closed intakes isn't your
> fixed-size extractor going to be starved for airflow once the cockpit
> pressure reaches its minimum, and that is going to in turn wind up
> disturbing the airflow over the extractor itself?
>
> --Noel

EXACTLY!! No extractor design optimized for a given airspeed and vent
opening will be optimal for all speeds and vent openings. When might
I close my vents (mostly)? Likely running near redline near cloudbase
or the PCA. (though that doesn't happen as often as I'd like!). I
made one for my Speed Astir (aka - the Grob solar sauna) right after
seeing the DG article. I have no idea how it changes the glider
performance, but it keeps ME from roasting quite so much, and that's
gotta' help!

[nurflugel[_2_]]

On Jul 25, 8:54*pm, Tim Taylor > wrote:

> I still think a reversed NACA duct will work better than the Butler
> and much better than the Mandl. *The Mandl throws the low speed air
> out into the faster air stream. *The JS design accelerates half the
> air over the airfoil but what happens to the air under the airfoil?

The NACA duct was designed such that the edges create vortices
which force the air into the duct. Reversing the flow through a NACA
duct is an inefficient way to exit fluid from a body.

[Tim Taylor]

On Jul 26, 9:05*am, nurflugel > wrote:
> On Jul 25, 8:54*pm, Tim Taylor > wrote:
>
> > I still think a reversed NACA duct will work better than the Butler
> > and much better than the Mandl. *The Mandl throws the low speed air
> > out into the faster air stream. *The JS design accelerates half the
> > air over the airfoil but what happens to the air under the airfoil?
>
> The NACA duct was designed such that the edges create vortices
> which force the air into the duct. Reversing the flow through a NACA
> duct is an inefficient way to exit fluid from a body.

Actually a "modified" NACA duct with an extended top cover that also
adjusts the angle of the exit stream and only allows about the last
third of the length to be open will accelerate the air back to proper
speed to match the outside air and place it gently into the air-
stream. It will have a smaller opening than the butler design and not
put the air out at about a 45 degree angle like the Mandl. It would
be very easy to modify the standard inlet design to be a very low drag
air exit. The NACA duct is designed to allow laminar flow of the air
through the duct and it will work both directions to accelerate as an
exit as well as decelerate when used as an inlet.

[sisu1a]

>It will have a smaller opening than the butler design and not
> put the air out at about a 45 degree angle like the Mandl.

The Mandl is not a 45 deg angle, it's far more subtle than that. It's
closer to 20 deg, maybe less. Here is a pic of part of the first one I
made, before mounting etc, which shows the angle kinda clearly:
http://i.imgur.com/gDmK6.jpg . It looks like this: http://i.imgur.com/X1O6n.jpg
mounted. I've seen a real Mandl and my proportions are very close. I
have flown with it on, and I can assure you it did not make excessive
noise. It does however allow my cockpit ventilation to actually work
though.That said, DG does have a strange louvered (it closes off most
of the surface area and has 3 angled louvers) fiberglass grill that
comes with a Mandl, to be taped over the opening. Need more info.

I don't use these to increase my ship's performance though, just to
increase my own comfort. I used to absolutely cook in my glider... no
longer. Here is my Butler hatch which I normally use on my ship:
http://i.imgur.com/e150n.jpg It does have a shallower angle than the
Mandl: http://i.imgur.com/zJGkx.jpg but I haven't noticed much
difference between the hatches, I just think the Butler one looks
cooler...

Both these vented hatches in fact make my own cockpit much quieter,
since I can now finally close my slider window and turn down the radio
and vario. I used to have to keep the slider open and keep my hand
outside the ship, cupped to force air in (I'm pretty sure my hand
sticking out was draggier than these vents are...), which *almost kept
me cool. These vents do the job much better. Pre exhaust vent, my
intakes flowed no air and only made noise (drag).

Following a similar line of thought as is laid out for the backwards
NACA led me to this mutation of the Mandl: http://i.imgur.com/tlmKh.jpg
, which quite by accident came out looking somewhat like a NACA scoop,
but rounded. That shape was made by attempting to follow established
wind tunnel spacial design guidelines, within the constraints of
obstructions inside my glider. There is a honeycomb grill that goes in
the opening to tame any air entering it. I have flown with it and it
works fine also. After the worlds, I'll share the pics of another more
exotic adaptation of it I made for another ship which may use it
there.

Side Mounting:
Here are some pics of Uncle Fuzzy's side mounted unit,
http://griderpirate.smugmug.com/gallery/3702283_9hEKD#355235760_LUSmZ
.. Which he has nothing but favorable reports of. Is it the optimal
location? In this case (and on any other ship with a hatch in a
similar location) I'm inclined to say yes, since no holes were cut to
put it on. If one *were to cut holes to permanently install one, the
location Butler identifies and JS also uses is prime, for a few
reasons. On my 59 I lucked out with the location of my hatch, which
although perhaps further back than truly optimal is in a great spot.
Most side mounted hatches look like an OK location too, and the
difference between OK and optimal locations are probably not large,
but that is just a guess on my part.

When my intake vents are closed, there is little-to-no airflow out the
exhaust vent. Mine so far have not proven to be noisy or problematic
with the vents closed. I forget it's there honestly, till I open my
intake and actually get air on my face that is...

-Paul

[Hans Disma]

Nothing news under the sun. My Phönix, the last one build out of 8, already
had a cockpitvent-system on the top of the fuselage behind the canopy, which
can be opened and closed in flight.
I have been trying to enclose a photo but I was unable to upload a photo.

Hans Disma


"sisu1a" > schreef in bericht
...
> Gotta hand it to Johan Bosman on this one... look at pg 5 of this pdf:
> http://www.streckenflug.at/news/js_communication_2010_07.pdf
> Personally I think his take on the exhaust vent is simply ingenious.
> The opening on that thing is immense and has got to allow much air to
> pass, but flow is organized by that little louver/wing. Pure genius.
>
> I may just be preoccupied on the subject right now since I'm in the
> middle of making vented ASW-20 hatches (Mandl and Butler styles) for
> the upcoming 20 gathering at Tehachapi. Pics to follow...
>
> -Paul

[Hans Disma]

For those of you who are unfamiliar with the Phönix. It first flew in 1957
and was the first aircraft made out of fiberglass.

Hans


"sisu1a" > schreef in bericht
...
> Gotta hand it to Johan Bosman on this one... look at pg 5 of this pdf:
> http://www.streckenflug.at/news/js_communication_2010_07.pdf
> Personally I think his take on the exhaust vent is simply ingenious.
> The opening on that thing is immense and has got to allow much air to
> pass, but flow is organized by that little louver/wing. Pure genius.
>
> I may just be preoccupied on the subject right now since I'm in the
> middle of making vented ASW-20 hatches (Mandl and Butler styles) for
> the upcoming 20 gathering at Tehachapi. Pics to follow...
>
> -Paul

[mike]

On Jul 26, 12:56*pm, "Hans Disma" > wrote:
> For those of you who are unfamiliar with the Phönix. *It first flew in 1957
> and was the first aircraft made out of fiberglass.
>
> Hans
>
> "sisu1a" > schreef in ...
>
> > Gotta hand it to Johan Bosman on this one... look at pg 5 of this pdf:
> >http://www.streckenflug.at/news/js_communication_2010_07.pdf
> > Personally I think his take on the exhaust vent is simply ingenious.
> > The opening on that thing is immense and has got to allow much air to
> > pass, but flow is organized by that little louver/wing. Pure genius.
>
> > I may just be preoccupied on the subject right now since I'm in the
> > middle of making vented ASW-20 hatches (Mandl and Butler styles) for
> > the upcoming 20 gathering at Tehachapi. Pics to follow...
>
> > -Paul

....and a beautiful sailplane, classic lines!

[Morgans[_2_]]

"Tim Taylor" > wrote

I still think a reversed NACA duct will work better than the Butler
and much better than the Mandl. The Mandl throws the low speed air
out into the faster air stream. The JS design accelerates half the
air over the airfoil but what happens to the air under the airfoil?

Reversed NACA ducts are poor at exhaust, from studies I have read. If you use
one like that, a small raised bump upwind of the vent helps greatly.
--
Jim in NC

[sisu1a]

> Nothing news under the sun. *My Phönix, the last one build out of 8, already
> had a cockpitvent-system on the top of the fuselage behind the canopy, which
> can be opened and closed in flight.
> I have been trying to enclose a photo but I was unable to upload a photo.

The Phoinix was ahead of it's time in even more regards than I
thought! The idea of venting cockpits isn't new, but it seems to have
been lost and rediscovered a few times since then. With each new
iteration though, different solutions to differing aspects of it have
continued to evolve, just like with wings. Wil Shuman brought it back
up in the 70s too but design continued on with predominantly
ineffective ventilation, being largely ignored (there are
exceptions...) by manufacturers until DG's 2008 release of the Mandl
(also right before the worlds...)

Butler was already using his vent in comps by that point, which
Bosman's is rooted in.The JS-1 vent is an entirely new take on an old
problem though, representing a clear departure from previous solutions
and was carefully designed using modern knowledge and computational
tools.

So far, the "WGC Six" seem to be doing well in a field of 51
http://www.flatlandcup.hu/2010/class_18m.php ships FWIW, taking 1st
place 2/3 practice days + decent overall placings, but it was already
a fabulous glider before the vent...

-Paul

PS. Hans, please PM me the photos of your Phonix vent!

[John Bojack[_2_]]

"Dave Nadler" > wrote in message
You mean, like the DG exit vents ?


No, like the Antares 220 volt electrical plug outlet and outboard fire
extinguisher bracket.