Fuselage Vents

Uncle Fuzzy decided that he'd like his ALTIMETER to read the same
pressure as his FLIGHT RECORDER when the pneumatic switch is in the
CABIN position on his line to the Altimeter.


Now there is a thought.... Open the air vent if you are close to airspace
to make the logger think you are lower, and fit an extraction vent if you
want that height record.

jim

On Jul 31, 9:40*am, Jim White wrote:
Uncle Fuzzy decided that he'd like his ALTIMETER to read the same
pressure as his FLIGHT RECORDER when the pneumatic switch is in the
CABIN position on his line to the Altimeter.

Now there is a thought.... Open the air vent if you are close to airspace
to make the logger think you are lower, and fit an extraction vent if you
want that height record.

jim

I'd think the relatively sudden increase (or decrease) in the delta
between the GPS altitude and the Baro altitude would raise suspicions.
I know I'd look at it if I saw a significant jump, and I'm not exactly
a rocket scientist.

In that case, I suppose you would have to go onto oxygen a little bit lower
down with the fuselage extraction vent fitted!

At 16:40 31 July 2008, Jim White wrote:

Now there is a thought.... Open the air vent if you are close to
airspace
to make the logger think you are lower, and fit an extraction vent if
you
want that height record.

jim

On Aug 2, 3:25*am, Derek Copeland
wrote:
In that case, I suppose you would have to go onto oxygen a little bit lower
down with thefuselageextractionventfitted!

At 16:40 31 July 2008, Jim White wrote:





Now there is a thought.... Open the airventif you are close to
airspace
to make the logger think you are lower, and fit an extractionventif
you
want that height record.

jim- Hide quoted text -

- Show quoted text -

I made this vent to replace the access hatch for connecting my
controls
http://griderpirate.smugmug.com/gall...55235771_pv8zu
Next weekend I will fly with a manometer to compare static to cabin
pressure with the 'normal' hatch, then the 'Mandl Extractor' hatch. I
can report subjectively that I was MUCH more comfortable in the
cockpit.

I made this vent to replace the access hatch for connecting my
controlshttp://griderpirate.smugmug.com/gallery/3702283_9hEKD#355235771_pv8zu
Next weekend I will fly with a manometer to compare static to cabin
pressure with the 'normal' hatch, then the 'Mandl Extractor' hatch. I
can report subjectively that I was MUCH more comfortable in the
cockpit.

Awesome! My SZD-59 is going to get one of these on it's booby hatch
now too, thanks for sharing!

-Paul

On Aug 19, 6:42*pm, sisu1a wrote:
* I made this vent to replace the access hatch for connecting my

controlshttp://griderpirate.smugmug.com/gallery/3702283_9hEKD#355235771_pv8zu
Next weekend I will fly with a manometer to compare static to cabin
pressure with the 'normal' hatch, then the 'Mandl Extractor' hatch. *I
can report subjectively that I was MUCH more comfortable in the
cockpit.

Awesome! My SZD-59 is going to get one of these on it's booby hatch
now too, thanks for sharing!

-Paul

Speaking of thanks.... in characteristic style, I neglected to than
Bob Kuykendall for his advice regarding mold making, and DG for
publishing their findings in the first place. Does any other glider
manufacturer 'share' as much? This is an honest question. I've spent
quite a lot of time on the DG site, very little on any others.

On Aug 19, 7:34*pm, Uncle Fuzzy wrote:

Speaking of thanks.... in characteristic style, I neglected to than
Bob Kuykendall for his advice regarding mold making, and DG for
publishing their findings in the first place. *Does any other glider
manufacturer 'share' as much? This is an honest question. *I've spent
quite a lot of time on the DG site, very little on any others.

You're quite welcome, of course. Nice looking piece, I think you
nailed the shape! Interesting to see how your idea follows that of
Dick Butler--exhausting the vent air on top instead of on the bottom.

Now you get to experience the joys of sanding, filling, sanding, and
painting a 3D shape... Some folks ask me why I still mold on gelcoat,
why do I do that when others have made a practice of molding bare and
painting afterwards? My general answer is so that I can put the orange
peel and pinholes on the inside where nobody will ever know they're
there.

Thanks, Bob K.

On Aug 20, 7:59*am, Bob Kuykendall wrote:
On Aug 19, 7:34*pm, Uncle Fuzzy wrote:

Speaking of thanks.... in characteristic style, I neglected to than
Bob Kuykendall for his advice regarding mold making, and DG for
publishing their findings in the first place. *Does any other glider
manufacturer 'share' as much? This is an honest question. *I've spent
quite a lot of time on the DG site, very little on any others.

You're quite welcome, of course. Nice looking piece, I think you
nailed the shape! Interesting to see how your idea follows that of
Dick Butler--exhausting the vent air on top instead of on the bottom.

Now you get to experience the joys of sanding, filling, sanding, and
painting a 3D shape... Some folks ask me why I still mold on gelcoat,
why do I do that when others have made a practice of molding bare and
painting afterwards? My general answer is so that I can put the orange
peel and pinholes on the inside where nobody will ever know they're
there.

Thanks, Bob K.

LOL! The bodywork is tedious but simple. I can do that. Next time
I'm going to get REAL tooling resin! BTW, I am getting senile. AFTER
all the pain of making a fiberglass mold from the hatch, I realized I
could have pulled one on my vacuum form in minutes. I even have
several flavors of theromplastics on hand. D'oh! Mold rigidity is
achieved by filling the back of the mold with plaster of paris, which
I ALSO had on hand. Maybe an hour of hands-on work to produce the mold.

On Aug 19, 9:15 pm, Uncle Fuzzy wrote:
On Aug 2, 3:25 am, Derek Copeland



wrote:
In that case, I suppose you would have to go onto oxygen a little bit lower
down with thefuselageextractionventfitted!

At 16:40 31 July 2008, Jim White wrote:

Now there is a thought.... Open the airventif you are close to
airspace
to make the logger think you are lower, and fit an extractionventif
you
want that height record.

jim- Hide quoted text -

- Show quoted text -

I made this vent to replace the access hatch for connecting my
controlshttp://griderpirate.smugmug.com/gallery/3702283_9hEKD#355235771_pv8zu
Next weekend I will fly with a manometer to compare static to cabin
pressure with the 'normal' hatch, then the 'Mandl Extractor' hatch. I
can report subjectively that I was MUCH more comfortable in the
cockpit.

Nice work.

Now DB is a pretty smart guy, so chances are he has this figured out.
But I sure don't. I can't see how exhausting air into the low
pressure area that's responsible for producing aerodynamic lift is a
good thing. Perhaps the mass flow is trivial and doesn't matter as
long as the flow isn't spoiled. But we sure go to a lot of effort to
eliminate air leaks in this area and sealing surely does help....

On Aug 20, 4:13*am, PMSC Member wrote:
On Aug 19, 9:15 pm, Uncle Fuzzy wrote:





On Aug 2, 3:25 am, Derek Copeland

wrote:
In that case, I suppose you would have to go onto oxygen a little bit lower
down with thefuselageextractionventfitted!

At 16:40 31 July 2008, Jim White wrote:

Now there is a thought.... Open the airventif you are close to
airspace
to make the logger think you are lower, and fit an extractionventif
you
want that height record.

jim- Hide quoted text -

- Show quoted text -

I made this vent to replace the access hatch for connecting my
controlshttp://griderpirate.smugmug.com/gallery/3702283_9hEKD#355235771_pv8zu
Next weekend I will fly with a manometer to compare static to cabin
pressure with the 'normal' hatch, then the 'Mandl Extractor' hatch. *I
can report subjectively that I was MUCH more comfortable in the
cockpit.

Nice work.

Now DB is a pretty smart guy, so chances are he has this figured out.
But I sure don't. *I can't see how exhausting air into the low
pressure area that's responsible for producing aerodynamic lift is a
good thing. *Perhaps the mass flow is trivial and doesn't matter as
long as the flow isn't spoiled. *But we sure go to a lot of effort to
eliminate air leaks in this area and sealing surely does help....- Hide quoted text -

- Show quoted text -
Thanks,
There's a link in the first post of this thread to an article on the
DG website that explains why they firgured there would be a
performance gain. DG placed their extractor behind and to the side
of the gear well. Mine is above and toward the rear of the wing
strictly because there was a control hookup access panel there,
allowing me to go back to original at any time. Perhaps not an ideal
location, but the only place I could put it without cutting my glider.
My motivation for the exhaust vent was comfort, and regardless of any
aerodynamic gains or losses, it certainly helps keep more comfortable
in the 100+ degree desert heat. Without the vent, I was hot even at
17,000 feet, with just the left side of my face cold where the canopy
vent blasted a thin stream of cold air.