JS-1 Exhaust Vent

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/gall...55235760_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

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_c...on_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

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_c...on_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

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_c...on_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!

"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

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!

"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.