Air Extractor: Better than a Plastic Jesus?

On Monday, December 16, 2013 7:06:18 PM UTC-5, waremark wrote:
If it improves performance why do Schempp and Schleicher
not instal it? They work very hard for improved performance.

Well, its a factory option for Antares, and excepting the
Antares located in Canada and north-west, all Antares in
North America have these vents. The exit duct improves cockpit
ventilation, and prevents air leaking out where it shouldn't
(a performance issue with nose intake and inadequate exhaust).


On Monday, 16 December 2013 19:23:31 UTC, Craig Funston wrote:
If Dick Butler believes in it, that's good enough for me :-)

Lange copied Dick, as did Schleicher ;-)
Some details he
http://www.nadler.com/public/2008_Uv...valde2008.html


See ya, Dave "YO electric"

I have two different fuselage air extractors on my LS8-18. The reason I did this is because I knew my cockpit was being pressurised because the canopy vent would pop open at 100kts and no air was entering the cockpit thru that now open vent.

The first one I installed was the then "holy grail" of extractors, the Mandle. This was installed as instructed by DG on the lower fuselage just aft of the gear doors. This was a hastle mainly because I had to enroll in the DG maintenance program to be able to buy the installation kit. Bottom line...NO CHANGE IN NOISE LEVELS IN THE COCKPIT AND NO CHANGE IN CANOPY AIR VENT POPPING OPEN AT 100KTS.

I then had Rex install the locally sourced airvent that is placed on the top of the fuselage just behind the canopy. Immediately quieter cockpit. Now I could feel air moving past my face when the forward vent was opened. The canopy airvent stays closed right up to redline.

Did it improve my L/D by 10 points? Can't tell you.

On Tuesday, December 17, 2013 8:56:35 AM UTC-6, wrote:

I then had Rex install the locally sourced airvent that is placed on the top of the fuselage just behind the canopy. Immediately quieter cockpit. Now I could feel air moving past my face when the forward vent was opened. The canopy airvent stays closed right up to redline.



Did it improve my L/D by 10 points? Can't tell you.

I'm seriously considering installing one on my LS6b this winter - where did you get yours from?

Kirk
66

On Tuesday, December 17, 2013 8:45:29 AM UTC-7, kirk.stant wrote:
On Tuesday, December 17, 2013 8:56:35 AM UTC-6, wrote:



I then had Rex install the locally sourced airvent that is placed on the top of the fuselage just behind the canopy. Immediately quieter cockpit. Now I could feel air moving past my face when the forward vent was opened.. The canopy airvent stays closed right up to redline.







Did it improve my L/D by 10 points? Can't tell you.



I'm seriously considering installing one on my LS6b this winter - where did you get yours from?



Kirk

66

This was discussed many, many years ago. As if you feel that with your cockpit vent open and your final glide is so critical, what Holighaus simply recommended was to "Close" your cockpit vent and stop doing final critictal glides! Whats needed is the cockpit air to "vent" and whats required to vent "all" that air. What one needs to also understand is that the fuselage is a main part of the structure strength for the prevention of flutter. It is highly suggested before cutting holes to discuss this with the manufacture.

On that DG vent, at the Worlds, it was used as a mental advantage ploy. As when statements were made that it "speeds up the exiting air" meant major discovery of a perpetual motion" had been discovered. Later, it was found as such and no performance increase was found. A sales ploy, well, maybe just another needed vent as getting "ALL" the air to exit takes more vents than gliders use. Also, exhausting air thru the wings has always been difficult to totally seal. This might help with that if used correctly.

A definition is needed on this:" Perpetual motion describes motion that continues indefinitely without any external source of energy.[2] This is impossible in practice because of friction and other sources of energy loss.[3][4][5] Furthermore, the term is often used in a stronger sense to describe a perpetual motion machine of the first kind, a "hypothetical machine which, once activated, would continue to function and produce work"[6] indefinitely with no input of energy. There is a scientific consensus that perpetual motion is impossible, as it would violate the first or second law of thermodynamics.[4][5]

Yes, JS did use a ASH 26 fuselage and agreements were then reached with AS on the continued use(my sources are very reliable on this). I have also used a very expensive manometer that reads down to a .0001 pressure difference.. I will say I wish I had my money back on that test. But my exhaust air has "more" than one way out as it escapes the aft area. If you load up your "behind head area" with all sorts of stuff, you are restricting the airflow out.

At least with the "new Vent" it stops you from doing this and this may be whats needed as a enlightenment for many folks and a few folks make a few more bucks!

Best, FWIW, #711.

On Tuesday, December 17, 2013 9:48:44 AM UTC-7, Tom Kelley #711 wrote:
On Tuesday, December 17, 2013 8:45:29 AM UTC-7, kirk.stant wrote:

On Tuesday, December 17, 2013 8:56:35 AM UTC-6, wrote:







I then had Rex install the locally sourced airvent that is placed on the top of the fuselage just behind the canopy. Immediately quieter cockpit. Now I could feel air moving past my face when the forward vent was opened. The canopy airvent stays closed right up to redline.















Did it improve my L/D by 10 points? Can't tell you.







I'm seriously considering installing one on my LS6b this winter - where did you get yours from?







Kirk



66



This was discussed many, many years ago. As if you feel that with your cockpit vent open and your final glide is so critical, what Holighaus simply recommended was to "Close" your cockpit vent and stop doing final critictal glides! Whats needed is the cockpit air to "vent" and whats required to vent "all" that air. What one needs to also understand is that the fuselage is a main part of the structure strength for the prevention of flutter. It is highly suggested before cutting holes to discuss this with the manufacture.



On that DG vent, at the Worlds, it was used as a mental advantage ploy. As when statements were made that it "speeds up the exiting air" meant major discovery of a perpetual motion" had been discovered. Later, it was found as such and no performance increase was found. A sales ploy, well, maybe just another needed vent as getting "ALL" the air to exit takes more vents than gliders use. Also, exhausting air thru the wings has always been difficult to totally seal. This might help with that if used correctly.



A definition is needed on this:" Perpetual motion describes motion that continues indefinitely without any external source of energy.[2] This is impossible in practice because of friction and other sources of energy loss.[3][4][5] Furthermore, the term is often used in a stronger sense to describe a perpetual motion machine of the first kind, a "hypothetical machine which, once activated, would continue to function and produce work"[6] indefinitely with no input of energy. There is a scientific consensus that perpetual motion is impossible, as it would violate the first or second law of thermodynamics.[4][5]



Yes, JS did use a ASH 26 fuselage and agreements were then reached with AS on the continued use(my sources are very reliable on this). I have also used a very expensive manometer that reads down to a .0001 pressure difference. I will say I wish I had my money back on that test. But my exhaust air has "more" than one way out as it escapes the aft area. If you load up your "behind head area" with all sorts of stuff, you are restricting the airflow out.



At least with the "new Vent" it stops you from doing this and this may be whats needed as a enlightenment for many folks and a few folks make a few more bucks!



Best, FWIW, #711.

As I just couldn't help myself on this, BUT, we have spent a lot of time, money and learning ways in sealing gear doors over the years to prevent air exhausting thru that area.

Does this now mean when you now fly inverted with the new vent, it has to be sealed to prevent a performance loss?..........Now about that plastic Jesus..................

Best for the holidays..........#711.

There is a fair bit of discussion on this topic on the ASW20Owners yahoo group, with some references to performance improvements that I believe were calculated for the JS1.

I have one installed on my ASW-20 and the difference in cockpit comfort in hot conditions is tremendous. Whistles around the canopy rails or other mystery channels go away and the glider is noticeably quieter.

The 20 is an easy solution because you can replace the control hatch cover. It's a positive enough improvement in cockpit comfort that I have considered adding a vent to my Duo. It was suggested that it was a "minor modification" that wouldn't require a 337.

I figured out the performance improvement on the 20, assuming the same .3N drag reduction claimed for the JS1. Works out to a whopping 120 extra feet of glide distance on a 1000ft loss assuming 40:1 glide.

I therefore love it for the cockpit comfort. I figure that the performance increase of being comfortable is more substantial than the slight possible reduction in drag or even an increase in drag.




On Tuesday, December 17, 2013 9:31:13 AM UTC-8, Tom Kelley #711 wrote:
On Tuesday, December 17, 2013 9:48:44 AM UTC-7, Tom Kelley #711 wrote:

On Tuesday, December 17, 2013 8:45:29 AM UTC-7, kirk.stant wrote:



On Tuesday, December 17, 2013 8:56:35 AM UTC-6, wrote:















I then had Rex install the locally sourced airvent that is placed on the top of the fuselage just behind the canopy. Immediately quieter cockpit. Now I could feel air moving past my face when the forward vent was opened. The canopy airvent stays closed right up to redline.































Did it improve my L/D by 10 points? Can't tell you.















I'm seriously considering installing one on my LS6b this winter - where did you get yours from?















Kirk







66







This was discussed many, many years ago. As if you feel that with your cockpit vent open and your final glide is so critical, what Holighaus simply recommended was to "Close" your cockpit vent and stop doing final critictal glides! Whats needed is the cockpit air to "vent" and whats required to vent "all" that air. What one needs to also understand is that the fuselage is a main part of the structure strength for the prevention of flutter. It is highly suggested before cutting holes to discuss this with the manufacture.







On that DG vent, at the Worlds, it was used as a mental advantage ploy. As when statements were made that it "speeds up the exiting air" meant major discovery of a perpetual motion" had been discovered. Later, it was found as such and no performance increase was found. A sales ploy, well, maybe just another needed vent as getting "ALL" the air to exit takes more vents than gliders use. Also, exhausting air thru the wings has always been difficult to totally seal. This might help with that if used correctly.







A definition is needed on this:" Perpetual motion describes motion that continues indefinitely without any external source of energy.[2] This is impossible in practice because of friction and other sources of energy loss.[3][4][5] Furthermore, the term is often used in a stronger sense to describe a perpetual motion machine of the first kind, a "hypothetical machine which, once activated, would continue to function and produce work"[6] indefinitely with no input of energy. There is a scientific consensus that perpetual motion is impossible, as it would violate the first or second law of thermodynamics.[4][5]







Yes, JS did use a ASH 26 fuselage and agreements were then reached with AS on the continued use(my sources are very reliable on this). I have also used a very expensive manometer that reads down to a .0001 pressure difference. I will say I wish I had my money back on that test. But my exhaust air has "more" than one way out as it escapes the aft area. If you load up your "behind head area" with all sorts of stuff, you are restricting the airflow out.







At least with the "new Vent" it stops you from doing this and this may be whats needed as a enlightenment for many folks and a few folks make a few more bucks!







Best, FWIW, #711.



As I just couldn't help myself on this, BUT, we have spent a lot of time, money and learning ways in sealing gear doors over the years to prevent air exhausting thru that area.



Does this now mean when you now fly inverted with the new vent, it has to be sealed to prevent a performance loss?..........Now about that plastic Jesus..................



Best for the holidays..........#711.