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Perlan High Altitude Tow Plane



 
 
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  #21  
Old August 18th 18, 10:00 AM
Ventus_a Ventus_a is offline
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Quote:
Originally Posted by Bruce Hoult View Post
On Monday, August 13, 2018 at 9:59:35 PM UTC-7, wrote:
On Monday, August 13, 2018 at 9:18:01 PM UTC-6, Frank Whiteley wrote:
http://www.reporterherald.com/lifest...s-stratosphere Arne is an SSA member and member of Colorado Soaring Association.


The article mentions "weight turbulence" I think that should read "wake turbulence. Shouldn't be an issue unless Perlan plans on boxing the wake.


Journalists never know what they're writing about. They mishear and don't understand anyway. They also never show their article to anyone with any knowledge of the subject matter before publishing. You see the very common result.
Maybe so Bruce but the amount of wake turbulence is a function of the weight being lifted so it's not too out of whack lol
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  #22  
Old August 24th 18, 01:55 AM posted to rec.aviation.soaring
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Default Perlan High Altitude Tow Plane

On Wednesday, August 15, 2018 at 10:13:37 PM UTC-5, Ramy wrote:
Typo aside, am I the only one somewhat disappointed to learn that the plan is to tow the Perlan to 50,000 feet, or I missread the article? I was kind of hoping the Perlan is capable of climbing to 90K from a reasonable tow altitude.

Ramy


What, Real Men scratch around for hours just to prove ...what?...
The fact is that Perlan was designed to fly in and study *stratospheric* wave, not tropospheric wave. These waves are rarely stacked and connected. Perlan I found such linked wave once in two years, and then set a record over 50,000 ft. Perlan II found such linked wave once in two years, and then set a record over 50,000 ft.

The hope is to do aerodynamic and atmospheric research in the stratosphere. In the winter, the tropopause (the boundary between tropo- and strato-sphere) generally descends to about 30,000 msl. It happens to be about 40,000 msl in the southern hemisphere at the moment.

The Egrett, used as a towplane, is able to reliably bring Perlan II into the lower reaches of the stratosphere in about an hour. Only in this way will the glider be a reliable research vehicle.

And such research is important: the polar night jets are poorly understood, yet are known to drive climate in some ways. It is not know what triggers stratospheric wave, and one of the hindrances to Perlan "success" is that predictive models are inaccurate simply because of human ignorance.

While it's spectacular to set altitude records, the real importance of this project is making steps toward stratospheric research in a vehicle that will not contaminate the nearby atmosphere with noise: chemical, mechanical, aerodynamic.

This is not a toy and its mission is not play.
DrDan Johnson
  #23  
Old August 24th 18, 03:01 AM posted to rec.aviation.soaring
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Default Perlan High Altitude Tow Plane

"This is not a toy and its mission is not play."

Yeah, maybe so, but it still looks like fun and an amazing, challenging project. Best of luck to all your endeavors. Say Hi to Jim, Jackie, Morgan, Sandra, Stewart, Liz, Tim, Tago and all of the other team members I will remember about two seconds after I hit "Post Entry."
  #24  
Old August 24th 18, 08:59 AM posted to rec.aviation.soaring
Peter Purdie[_3_]
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Default Perlan High Altitude Tow Plane

Do I recall correctly that Einar Enevoldson descibed the Egrett as the
worst plane he ever flew (and considering some of the candidates at
NASA Dryden, that would be an amazing distiction).

At 02:01 24 August 2018, wrote:
"This is not a toy and its mission is not play."

Yeah, maybe so, but it still looks like fun and an amazing, challenging
pro=
ject. Best of luck to all your endeavors. Say Hi to Jim, Jackie, Morgan,
Sa=
ndra, Stewart, Liz, Tim, Tago and all of the other team members I will
reme=
mber about two seconds after I hit "Post Entry."


  #25  
Old August 24th 18, 05:00 PM posted to rec.aviation.soaring
Steve Leonard[_2_]
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Default Perlan High Altitude Tow Plane

On Friday, August 17, 2018 at 8:55:12 AM UTC-5, AS wrote:

Stu,
I think that has actually been done already in Russia a while back. I put a reference to an article describing that process in our 'winchdesign' forum but since Yahoo got hacked, most of the links to those references are lost.
The glider was towed up like a normal aero-tow. Then, the line was paid out and the tow plane started a descent which allowed the glider to climb like it would in a winch launch.

Uli
'AS'


Described in the book "Without Visible Means of Support" by Richard Miller. A very good read.

Oh, and the Russians also did testing where they towed a glider up and intentionally jettisoned parts of it in flight to determine controlability.

Steve Leonard

  #26  
Old August 24th 18, 08:21 PM posted to rec.aviation.soaring
Bob Kuykendall
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Default Perlan High Altitude Tow Plane

On Thursday, August 23, 2018 at 5:55:25 PM UTC-7, wrote:

While it's spectacular to set altitude records, the real importance of this project is making steps toward stratospheric research in a vehicle that will not contaminate the nearby atmosphere with noise: chemical, mechanical, aerodynamic.

This is not a toy and its mission is not play.


On that basis, wouldn't you be much better off doing your oh-so-serious research with a UAV?

--Bob K.

  #27  
Old August 24th 18, 09:12 PM posted to rec.aviation.soaring
Martin Gregorie[_6_]
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Default Perlan High Altitude Tow Plane

On Fri, 24 Aug 2018 12:21:03 -0700, Bob Kuykendall wrote:

On Thursday, August 23, 2018 at 5:55:25 PM UTC-7,
wrote:

While it's spectacular to set altitude records, the real importance of
this project is making steps toward stratospheric research in a vehicle
that will not contaminate the nearby atmosphere with noise: chemical,
mechanical, aerodynamic.

This is not a toy and its mission is not play.


On that basis, wouldn't you be much better off doing your oh-so-serious
research with a UAV?

Possible/probable reasons why Perlan 2 is the best choice:

- Perlan 2 already exists.

- There are no electric UAVs with a similar flight envelope.

- Any powered replacement has to be electric to avoid atmospheric
exhaust contamination.

- Even an electric UAV will add unwanted disturbances with its prop wake.


--
Martin | martin at
Gregorie | gregorie dot org
  #28  
Old August 24th 18, 10:00 PM posted to rec.aviation.soaring
Bob Kuykendall
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Default Perlan High Altitude Tow Plane


Possible/probable reasons why Perlan 2 is the best choice:

- Perlan 2 already exists.


And, hey, the made production-quality wing and fuselage tooling for it, so they can make more if they want!

- There are no electric UAVs with a similar flight envelope.

- Any powered replacement has to be electric to avoid atmospheric
exhaust contamination.

- Even an electric UAV will add unwanted disturbances with its prop wake.


This isn't about electric versus unpowered. It's about the necessity of doing this with a crewed vehicle. There is nothing in any of those arguments that supports carting two humans and several hundred pounds of life-support infrastructure around the sky.

I'm sure that there are valid arguments for having humans aboard so they can respond adaptively and innovatively to any flight or scientific situation that might arise. I simply don't buy the idea that doing so is best or even lowest-cost option. I think that a UAV, or a cooperative swarm of UAVs, or even a series of balloon-dropped UAVs, could do the planned research with a risk/reward ratio about an order of magnitude better.

--Bob K.
  #29  
Old August 25th 18, 01:48 AM posted to rec.aviation.soaring
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Default Perlan High Altitude Tow Plane

Perlan is cool as hell. And I'm glad they are doing it manned, but I have to chuckle at the 'serious science stuff.' All the great explorers from years back used to admit the science part was just to get funding so they could go off adventuring. And there is nothing wrong with that, matter of fact it is awesome.
  #30  
Old August 25th 18, 01:55 AM posted to rec.aviation.soaring
Martin Gregorie[_6_]
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Default Perlan High Altitude Tow Plane

On Fri, 24 Aug 2018 14:00:59 -0700, Bob Kuykendall wrote:

This isn't about electric versus unpowered. It's about the necessity of
doing this with a crewed vehicle. There is nothing in any of those
arguments that supports carting two humans and several hundred pounds of
life-support infrastructure around the sky.

Sure, but would you be happy to tow an autonomous glider above the lower
stratospheric boundary?

I'm sure that there are valid arguments for having humans aboard so they
can respond adaptively and innovatively to any flight or scientific
situation that might arise. I simply don't buy the idea that doing so is
best or even lowest-cost option. I think that a UAV, or a cooperative
swarm of UAVs, or even a series of balloon-dropped UAVs, could do the
planned research with a risk/reward ratio about an order of magnitude
better.

Isn't there a fairly radical bit of mission redesign going on? IIRC
Fossett and Einevold were set up the Perlan because they could and to
push the record up as high as they could, with a bit of science thrown in
as well, but now DrDan Johnson (and Airbus) are saying that was all very
well then but NOW the project is all grown up and concentrating on
Serious Meteorological Science.

You may well be right than an unmanned vehicle can do it cheaper if the
mission was designed that way from the start. All I'm really saying is
that wasn't how it happened.

Judging by an article by Jean-Marie Clement in Sailplane & Gliding (Dec/
Jan 18 p40) the Perlan Project may have missed the boat for setting a
properly high record. M. Clement says that climate change has stretched
the Andean wavelength by causing and increase in wind speed, so it is no
longer in phase with the mountain topography. This weakens wave lift
while the increased wind speed has also reduced the duration of weather
cycles. He talks about having to accept 2-3 m/s wave climbs in 2017 where
a decade ago they'd have had 5-8 m/s, but adds that the vertical velocity
in hydraulic jumps wasn't affected though the jumps may have become more
frequent.


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Gregorie | gregorie dot org
 




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