New Vent!

On Dec 8, 12:46*pm, CLewis95 wrote:
from Paul (sisu1a):

..... *But as I understand it, the
pressure at the tail is kinda on a ship by ship basis. Some ships even
suck water up the tailpipe when blowing ballast, which is a pretty
good indicator of a poor choice for a 'low pressure' location.
...

Paul (ALL)

I have this problem with my Genesis 2 (both water and "other" fluids).

Does this come from a "venturi" effect of air leaking from Horz/Vert
Stab Junction or poor Rudder Sealing? *It amazes me how much gets
sucked back into fuselage. *(Genesis has VERY short fuselage)

Another Genesis owner (DK) has experimented with an exit duct out the
fuse hatch over wings. ... comments Don???

Curt - 95
Likely due to pressure recoveing over the very short length of
fuselage and large reduction in cross section
over that length. High location closer to centerline would probably
better in order to avoid effects on root fillet
area.
Just speculating- It's cold here.
UH

I have this problem with my Genesis 2 (both water and "other" fluids).

Does this come from a "venturi" effect of air leaking from Horz/Vert
Stab Junction or poor Rudder Sealing? *It amazes me how much gets
sucked back into fuselage. *(Genesis has VERY short fuselage)

Another Genesis owner (DK) has experimented with an exit duct out the
fuse hatch over wings. ... comments Don???

Curt - 95


I have had an air outlet on my Genesis2 for several years. It was
modeled after the outlet on DB's ASW-22. It seems to work very well.
Curt is correct that on a Genesis 2, dumped water ballast will enter
the fuselage thru the fairings over the rudder horns. These fairings
are suppose to be the air outlets. I have taken photos of that area
with tufts taped around the fairings. And indeed the tufts turn and
are sucked into the "outlets".

Don (DK)

On Dec 7, 10:46*am, Mike the Strike wrote:
On Dec 7, 7:56*am, Andy wrote:





On Dec 6, 7:37*pm, sisu1a wrote:

http://tinyurl.com/337bok7**...I'm sure it works like a champ. *Nice
work John/Hank/Dick!

Looks nice but where do I put all the stuff that now sits in the over-
spar storage area? *I don't think I want to discard my landout kit so
I can fit a vent system that has an unknown (to me) performance
advantage.

For me to be interested in a kit for the ASW-28 it would have to
extend the storage area aft so that, with the vent kit installed, at
least the same storage volume was still available, preferably more.
There is lots of room to extend backwards as is done in the 27's.
Unlike shorter pilots there in no room behind my seat and everything I
carry has to go just forward of, or over the spar.

Where can I find a picture of the installation looking aft into the
spar area?

Andy

An interesting gadget. *However, wouldn't it be more logical to vent
nearer the rear of the fuselage, say in the lower tail?

Mike- Hide quoted text -

- Show quoted text -

I have an exit vent in the lower aft area of the fuselage of both my
'27 and '28. With all the other stuff done sealing rudder hinge,
elevator drive, horn splitters, etc, it improved negative pressure and
flow and resulted in less noise. This vent is a huge ass ache to put
in with the associated nozzle, has significant structural implications
requiring reinforcement, and simply, is not for the faint hearted.
The new vent on top is in a low pressure area which helps a lot with
getting flow and reduced cockpit pressure. It also takes an hour and a
half to install instead of about 10 hr. It's structural implications
are minimal. It slightly reduces available baggage storage in the top
center 4 inches.
Both my gliders will have rear vents closed this winter and '28 will
get top vent.
FWIW
UH

Do you blokes suffer from major flatulence problems? Seems a lot of effort
to remove air from the cockpit but I could understand if the air was
contaminated in some way :-)



At 19:16 07 December 2010, wrote:
On Dec 7, 10:46=A0am, Mike the Strike wrote:
On Dec 7, 7:56=A0am, Andy wrote:





On Dec 6, 7:37=A0pm, sisu1a wrote:

http://tinyurl.com/337bok7=A0=A0...I'm sure it works like a champ.
=A0=
Nice
work John/Hank/Dick!

Looks nice but where do I put all the stuff that now sits in the
over-
spar storage area? =A0I don't think I want to discard my landout
kit
so
I can fit a vent system that has an unknown (to me) performance
advantage.

For me to be interested in a kit for the ASW-28 it would have to
extend the storage area aft so that, with the vent kit installed, at
least the same storage volume was still available, preferably more.
There is lots of room to extend backwards as is done in the 27's.
Unlike shorter pilots there in no room behind my seat and everything
I
carry has to go just forward of, or over the spar.

Where can I find a picture of the installation looking aft into the
spar area?

Andy

An interesting gadget. =A0However, wouldn't it be more logical to
vent
nearer the rear of the fuselage, say in the lower tail?

Mike- Hide quoted text -

- Show quoted text -

I have an exit vent in the lower aft area of the fuselage of both my
'27 and '28. With all the other stuff done sealing rudder hinge,
elevator drive, horn splitters, etc, it improved negative pressure and
flow and resulted in less noise. This vent is a huge ass ache to put
in with the associated nozzle, has significant structural implications
requiring reinforcement, and simply, is not for the faint hearted.
The new vent on top is in a low pressure area which helps a lot with
getting flow and reduced cockpit pressure. It also takes an hour and a
half to install instead of about 10 hr. It's structural implications
are minimal. It slightly reduces available baggage storage in the top
center 4 inches.
Both my gliders will have rear vents closed this winter and '28 will
get top vent.
FWIW
UH

In article ,
Don Johnstone wrote:

Do you blokes suffer from major flatulence problems? Seems a lot of effort
to remove air from the cockpit but I could understand if the air was
contaminated in some way :-)

Around here (northern Virginia) there's a month or two of summer where I
spend pretty much the entire flight with my hand stuck outside to get as
much air in as possible to try to stay cool. On one miserably hot day
this past July I had to cut a flight short as I began to seriously
overheat despite all my best efforts. I have one of Paul's extractors on
order and I'm hoping it'll make next summer much more pleasant.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

On Dec 7, 12:47*pm, Don Johnstone wrote:
Do you blokes suffer from major flatulence problems? Seems a lot of effort
to remove air from the cockpit but I could understand if the air was
contaminated in some way :-)

At issue is that ventilation air tends to pressurize the cockpit, and
then leak out around the canopy perimeter. Anywhere that there is air
escaping through the canopy frame gap, that leak will trip the
boundary layer and increase drag. If you can keep the cockpit at lower
than ambient pressure, you run a good chance of maintaining laminar
flow across the gap between the fuselage and the canopy, which can
result in several more square feet of laminar flow than you had
previously.

I happen to think that many original designers got it right; that the
most effective vent is back at the base of the rudder, where it is
convenient to exhaust air around the rudder cable horns.
Unfortunately, something often got lost in translation, and most
production gliders allow too little exhaust area through the vertical
fin spar, causing inadequate ventilation flow and too much cockpit
pressure. They also offer many restrictions on the path from the
cockpit to the tailboom, which reduces the flow rate.

So I think that these trendy exhaust vents, while perhaps not the best
possible solution, are still a lot better than you can get without
removing the rudder and doing some relatively major surgery on the fin
spar.

Thanks, Bob K.
http://www.hpaircraft.com

On Dec 8, 11:20*am, Bob Kuykendall wrote:
On Dec 7, 12:47*pm, Don Johnstone wrote:

Do you blokes suffer from major flatulence problems? Seems a lot of effort
to remove air from the cockpit but I could understand if the air was
contaminated in some way :-)

At issue is that ventilation air tends to pressurize the cockpit, and
then leak out around the canopy perimeter. Anywhere that there is air
escaping through the canopy frame gap, that leak will trip the
boundary layer and increase drag. If you can keep the cockpit at lower
than ambient pressure, you run a good chance of maintaining laminar
flow across the gap between the fuselage and the canopy, which can
result in several more square feet of laminar flow than you had
previously.

I happen to think that many original designers got it right; that the
most effective vent is back at the base of the rudder, where it is
convenient to exhaust air around the rudder cable horns.
Unfortunately, something often got lost in translation, and most
production gliders allow too little exhaust area through the vertical
fin spar, causing inadequate ventilation flow and too much cockpit
pressure. They also offer many restrictions on the path from the
cockpit to the tailboom, which reduces the flow rate.

So I think that these trendy exhaust vents, while perhaps not the best
possible solution, are still a lot better than you can get without
removing the rudder and doing some relatively major surgery on the fin
spar.

Thanks, Bob K.http://www.hpaircraft.com

.... and as JS pointed out, many of us fly where it is REALLY hot, with
ambient temperatures of 43c, 110f, and closed cockpit temperature over
55c, 130f. It doesn't take long at that temperature to ruin an
otherwise great flying day.

What keeps rain, wasps, mice, etc. from entering the vent hole when on
the ground?

On Dec 9, 3:11*am, "Matt Herron Jr." wrote:
What keeps rain, wasps, mice, etc. from entering the vent hole when on
the ground?

We don't have mice running around on our launch grid and rarely grid
in the rain. Guess I just didn't think
about those problems.
UH

At 08:11 09 December 2010, Matt Herron Jr. wrote:
What keeps rain, wasps, mice, etc. from entering the vent hole when on
the ground?



Canopy cover?