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ASW 24&27 rear fuselarge vents?



 
 
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  #1  
Old October 23rd 03, 04:48 PM
Udo Rumpf
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Default ASW 24&27 rear fuselarge vents?

Hi all,
to day I checked, what I thought was the rear exhaust vent of the ASW24.
I tried, after removing the rudder, insert a thin wire past the tail wheel fender.
I could not get this thin flexible wire through.
I inserted a long vacuum hose from the cockpit side, to the very end of the tail
and hook up the blower side. The results were feeble indeed.
What have other ASW 24 or 27 owners done to improve this situation?
Regards
Udo
  #2  
Old October 23rd 03, 05:40 PM
John Morgan
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"Udo Rumpf" wrote in message
.. .
Hi all,
to day I checked, what I thought was the rear exhaust vent of the ASW24.
I tried, after removing the rudder, insert a thin wire past the tail wheel
fender.
I could not get this thin flexible wire through.
I inserted a long vacuum hose from the cockpit side, to the very end of the
tail
and hook up the blower side. The results were feeble indeed.
What have other ASW 24 or 27 owners done to improve this situation?
Regards
Udo

Udo,

I suspected exhaust venting may be limiting cockpit ventilation on my
ASH26E. I haven't finished testing yet, but what I have done is to hook up a
shop-vac, on blow mode (after carefully cleaning it!), to the nose inlet to
pressurize the cockpit. I didn't have the wings attached, so taped up all
the fuselage wing root openings. The only outflow I could detect was at the
rudder cable fairing at the tail - - nothing at the gear or engine bay
doors.

On my non-scientific test, the flow was obviously restricted (the shop-vac
puts out a lot of air) as my temporary wing root covers ballooned out from
the pressure.

I plan to check cockpit vent flow with and without a temporary reverse scoop
in the plexi window etc. And also repeating the shop-vac test with wings
attached to make sure none is leaking out through wing openings - - I doubt
it is.

I've seen a picture of a 26E with a reverse facing, flush scoop on the lower
cockpit fuselage side . . . so others have dealt with this issue and come up
with solutions of their own. Any other info would be welcome . . .
--
bumper - ZZ
"Dare to be different . . . circle in sink."
to reply, the last half is right to left





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  #3  
Old October 24th 03, 12:09 AM
JJ Sinclair
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Hi Udo,
My ASH-25 was emitting a very loud squeal as I went through the finish gate at
redline (above 500 feet of course). I removed the rudder and found no way for
vent air to get out, so I drilled a 1" X 2" hole in the tail wheel fender.
Worked fine and the cockpit ventilation got a bunch better. As you know, the
exit hole should be 1.5 times the entry hole size.

On my nimbus 3, I enlarged the hole in the vertical fin spar and also polished
out the rudder cable exit guides with a sanding roll on a rod, driven by a
drill motor. Unfortunately, some major sailplane manufacturers don't do much,
if anything, about providing an efficient airflow exit system and if we don't
let it out in the tail area, the vent air will go looking for a way out in
other places, like the wings, landing gear doors and canopy seal.

JJ Sinclair
  #4  
Old October 24th 03, 12:18 AM
Greg Arnold
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Default


JJ Sinclair wrote:

Hi Udo,
My ASH-25 was emitting a very loud squeal as I went through the finish gate at
redline (above 500 feet of course). I removed the rudder and found no way for
vent air to get out, so I drilled a 1" X 2" hole in the tail wheel fender.
Worked fine and the cockpit ventilation got a bunch better. As you know, the
exit hole should be 1.5 times the entry hole size.

On my nimbus 3, I enlarged the hole in the vertical fin spar and also polished
out the rudder cable exit guides with a sanding roll on a rod, driven by a
drill motor. Unfortunately, some major sailplane manufacturers don't do much,
if anything, about providing an efficient airflow exit system



Do all manufacturers ignore exit air? If not, which ones take this into
account in their designs?


and if we don't
let it out in the tail area, the vent air will go looking for a way out in
other places, like the wings, landing gear doors and canopy seal.

JJ Sinclair


  #5  
Old October 24th 03, 12:44 AM
Udo Rumpf
external usenet poster
 
Posts: n/a
Default

My ASH-25 was emitting a very loud squeal as I went through the finish
gate at
redline (above 500 feet of course). I removed the rudder and found no way

for
vent air to get out, so I drilled a 1" X 2" hole in the tail wheel fender.
Worked fine and the cockpit ventilation got a bunch better. As you know,

the
exit hole should be 1.5 times the entry hole size.

On my nimbus 3, I enlarged the hole in the vertical fin spar and also

polished
out the rudder cable exit guides with a sanding roll on a rod, driven by a
drill motor. Unfortunately, some major sailplane manufacturers don't do

much,
if anything, about providing an efficient airflow exit system and if we

don't
let it out in the tail area, the vent air will go looking for a way out in
other places, like the wings, landing gear doors and canopy seal.

JJ Sinclair


  #6  
Old October 24th 03, 01:02 AM
Udo Rumpf
external usenet poster
 
Posts: n/a
Default

Sorry about the previous message.
I became suspicious when I noticed reams of foam
around the canopy as well as the cockpit opening,
to the point that the canopy would not line up along the fuselage line,
The brass bushing that holds the canopy down and locked was worn out, I
assume because of it.
I have a generous exit vent on my other glider and no seal on the canopy.
The fit is no better or worse than any other glider, still the cockpit is
relatively quiet through out the speed range.
Udo

 




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