Slashdot is powered by your submissions, so send in your scoop

 



Forgot your password?
typodupeerror
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. ×
Education Science Technology

Students' Experiments To Fly By Glider To the Edge of Space 55

techmage writes: In 2002 Steve Fossett and Einar Enevoldson set the altitude record for a glider climbing to 42,000 feet in the Perlan I. This year the Perlan II glider will attempt to reach over 90,000 feet. Carried aboard will be be 10 science experiments from students participating in a Teachers in Space contest. Some of these experiments push the boundaries of what can be done at the K-12 level. This news article has a lot more detail on what these kids are sending.
This discussion has been archived. No new comments can be posted.

Students' Experiments To Fly By Glider To the Edge of Space

Comments Filter:
  • by Viol8 ( 599362 ) on Monday March 21, 2016 @04:55AM (#51741885) Homepage

    I can't see from the article or the wonkypedia page where they expect to get enough speed from to retain that sort of altitude. They mention carried aloft by air currents (mountain waves). Err , even assuming those currents will get you to 90K feet (I doubt it) they're not going to get you to the 200-300 knots (heavier U-2 need to do 370 but it was "only" at 70K feet) you'll need to maintain that altitude without them guys. So unless by "gliding" they simply mean falling fast from height until they hit another updraft then to me this seems a bit of a non starter.

    • by Tx ( 96709 ) on Monday March 21, 2016 @06:10AM (#51742045) Journal

      You implied that you read the wikipedia article; well, it explains the specific weather phenomenon that is to be used to reach above 90k feet.

      "Standing waves normally do not extend above the tropopause at temperate latitudes. A strong west wind usually decreases above the tropopause, which has been shown to cap or prevent the upward propagation of standing mountain waves. However, at the outer boundary of the polar vortex, in winter, the stratospheric polar night jet exists. Its wind field can join with the wind field of the polar jet stream. The result is a wind which increases with altitude through the tropopause and upward to 100,000 feet or above. When this conjunction of winds occurs over a barrier mountain, standing mountain waves will propagate through that entire altitude range."

      And once that altitude is reached, presumably if the standing mountain wave can get you up to that altitude, it can also keep you up there, if you can ride it. Again, from the wiki page;

      "A sailplane can maneuver precisely at very high altitudes to traverse or remain relatively stationary in a desired portion of the wave structure, as the structure is determined in flight."

      • Re: (Score:2, Interesting)

        by Viol8 ( 599362 )

        The wind may well increase with altitude but the air density gets exponentially lower with altitude and at 90K its virtually a vacuum so you'd need a supersonic wind to even notice any significant affect on a plane the size of a glider.

        • Re: (Score:2, Insightful)

          by Anonymous Coward

          Let's assume that somebody involved has done some sums, looked at previous comparable attempts, and deduced that it's at theoretically possible, shall we? Airbus and Windward Performance do actually know a thing or two about the subject, and it wouldn't have got this far if it was pointless, so I think I'll take their opinion over some random guy on the internet.

          • by Viol8 ( 599362 )

            You ever considered that perhaps "some random guy on the internet" actually knows a thing or two about aeronautics himself? This is a tech site, not snapchat.

          • Let's assume that somebody involved has done some sums, looked at previous comparable attempts, and deduced that it's at theoretically possible, shall we? Airbus and Windward Performance do actually know a thing or two about the subject, and it wouldn't have got this far if it was pointless, so I think I'll take their opinion over some random guy on the internet.

            I'm inclined to agree. But just try substituting in "subprime mortgages" for "high-altitude glider", and substituting "the entire U.S. banking industry" in place of "Airbus and Windward Performance", and you'll start to see why appeals to authority aren't quite as reassuring as they used to be.

        • by Vihai ( 668734 )
          Such glider with probably fly around 60 kt (IAS) with at 90.000 feet would be 168 kt (TAS), not supersonic at all. The only aerodynamic issue is resistance to flutter which has been accounted for.
      • by Anonymous Coward
        The problem is at those altitudes you need either a LOT more speed or massive oversized wings that are very light as the air is so thin it provides very little lift which I what I think the OP was getting at. It isn't simply a problem of getting up their on an updraft, maintaining the height requires a significant increase in speed to counteract the lack of lift once you are out of that updraft.
  • by Anonymous Coward

    For those struggling to understand the title:

    Glider to fly students' experiments to the edge of space.

  • Saftey & Planning (Score:5, Insightful)

    by ebonum ( 830686 ) on Monday March 21, 2016 @05:26AM (#51741961)

    I'm a licensed pilot. If I was preparing to fly a glider twice as high as the previous record, I'm not sure I would want anything on my plane not 100% required for my flight. The first concern is weight. The second concern is that I really don't need anything extra to worry about. There are already enough risks involved. I'm not an expert on the flight envelops for gliders at this kind of altitude, but I'm going to guess that the plane will be at the knife edge between stalling and over speed. Gliders at 10,000 feet on a hot summer day get bounced around. A lot. They have shoulder straps for a reason. Storms have been known to remove their wings. Where there is powerful rising air, falling air can't be too far away. At 70, 80, 90,000 feet, a plane with huge, long wings might struggle to deal with the air currents.

    An unmanned balloon can hit 90,000 feet and carry a small payload. There are other ways to get these experiments to the edge of space.

    • Re:Saftey & Planning (Score:5, Informative)

      by vyvepe ( 809573 ) on Monday March 21, 2016 @05:39AM (#51741987)
      They do not want to catch a raising column of hot air (thermal). They want to catch a wave downwind of a mountain. The waves reach considerably higher than the mountain which generates them. Thermals are typically very bumpy. Waves are typically extremely steady. Only their middle part (the rotor) is bumpy but you can avoid that. This should be quite a steady flight.
      • Re:Saftey & Planning (Score:4, Interesting)

        by ebonum ( 830686 ) on Monday March 21, 2016 @06:19AM (#51742063)

        Good points. Not all wave flights are so smooth:
        http://www.aviationtoday.com/r... [aviationtoday.com]
        http://www.paul.moggach.yorkso... [yorksoaring.com]
        No one knows how high these waves travel, much less the edges of the rising, mid and falling air. You can't see rising air. There might be a cloud at the top. If it is there at 90,000 feet, I doubt it will be of much help when you are 20,000 feet below it. Instruments (total energy compensated variometer) can tell you if you are going up or down. Bumping into the edges tells you where the edge is.

        • by vyvepe ( 809573 )
          An experienced glider pilot has one more vairometer to use - his own posterior. One can feel speed changes in it :) Also one does not see how air moves, the pilot can feel whether the plane is nearing the turbulent region. This together with general knowledge about thermal ans waves helps a great deal.

          No idea why Bigelow screwed up. Gliders are built for turbulent weather. When one is targeting thermals then it is the turbulent parts of the atmosphere the plane is heading to. Stall speed is typically about

          • Re:Saftey & Planning (Score:4, Informative)

            by BESTouff ( 531293 ) on Monday March 21, 2016 @07:29AM (#51742365)

            An experienced glider pilot has one more vairometer to use - his own posterior. One can feel speed changes in it :)

            Nope. As you say it, own own posterior is an accelerometer, measuring the speed changes, NOT a variiometer, measuring the speed i.e. the position change. You're one derivative wrong.

            Piloting without vario is easy to do when you have visual cues around to help assessing your vertical speed, but when higher up in the sky it's really difficult to tell the difference between a steady +1m/s and -1m/s. (World class paraglider competition pilot here, and from the few flights I did in sailplane it's not much different).

            • by vyvepe ( 809573 )

              An experienced glider pilot has one more vairometer to use - his own posterior. One can feel speed changes in it :)

              Nope. As you say it, own own posterior is an accelerometer, measuring the speed changes, NOT a variiometer, measuring the speed i.e. the position change. You're one derivative wrong.

              Right, one cannot integrate it in head for more than a second or few. I wanted to express it is good enough to detect where turbulent air region starts. And from the safety point of view, if you have enough height then it does not matter much whether you are raising or falling. The ground is still far away to have time to correct it before crashing. And near the ground you can even see it. It is important to know the speed so that one does not stall or cross Vne. But even if speed dial would break in some v

              • Had you flown with a really good glider pilot, you might change your mind.
                I did a coaching flight with 4 time world champion Ingo Renner. He could map a thermal in 3D in his head incredibly well, and keep it going. Guys like him are just astonishing in their ability to read and predict the air.

        • by Vihai ( 668734 )
          Nope, wave flying in a glider is always smooth. Entering in a wave at 850 km/h may not be.
    • by techmage ( 72232 )

      I understand the concern and yes, the experiments could fly on a balloon - as has been done many times. The advantage of the glider is level stable flight. You cannot effectively steer a balloon, it mus be carried by the winds. The glider gives us the advantage (to a better degree) of picking the direction to fly in. If an experiment picks up something interesting on its instruments, the glider can fly back. The balloon cannot.

      The Perlan II was designed with the payload capability in mind. It is also why th

    • by Viol8 ( 599362 )

      "Powerful" is relative. At 100K feet its virtually a vacuum so even the fastest winds would seem like little more than a gentle breeze if you were standing in it.

      • by techmage ( 72232 )

        You are correct at the relative strength of the winds at that altitude. It was such a problem that airflow to the biological experiments had to be adjusted so we could get enough of a sample rate. That altitude is a good analog for Mars.

  • Well, we've had a nice conversation, and nobody is mentioning the obvious question: what is the racial makeup of these students that are having their experiments carried aloft? I see one in Georgia, a historically African-American state, and Puerto Rico, Latino, but the rest look as lily-white as the X Games. How did Slashdot miss this angle of the story? News for nerds, remember? Stuff that matters.

    And the really easy one - what kind of shirt was the spokesman wearing when he made the announcement? Th

    • Re: (Score:3, Informative)

      by techmage ( 72232 )

      The teams selected were not chosen with any race or gender elements in mind, only the science. But we have two teams predominately African American, one Latino team and the other teams are made up of blended groups. Some groups as you have correctly pointed out, have little to no minority presence (we are working on that). For the record, not all groups have posted photos, not were all the photos posted suitable for media use.

      There are an almost even number of girls to boys with the girls edging out the boy

  • by bkmoore ( 1910118 ) on Monday March 21, 2016 @10:03AM (#51743679)
    I'm no aeronautical engineer, only a pilot. [For cultural reasons glider pilots prefer the term sailplane, but I use glider here.] Gliders have a speed range. The minimum speed is the speed where the wings can produce enough lift to counteract gravity. The maximum speed is where flutter starts to occur, which can make the airplane uncontrollable and damage the airframe. In powered aircraft, this speed is usually expressed in terms of Mach. Most sport gliders that I am familiar with have a speed range between about 60 kmh and 200 kmh or 32 knots to 107 knots. I'm assuming that if you want to reach 90.000 feet in sustained flight, you would design a glider to have a much lower minimum speed than a standard sports glider, say 10 knots for arguments sake or 18.52 kmh. Lets also assume that the maximum speed remains at 200 kmh or 107 knots. At sea level the speed of sound is 665 knots. For a V_ne of 107 knots, your maximum speed can be expressed as Mach 0.16. At this point flutter begins.

    Now take our glider to 90.000 feet. At that altitude, assuming standard atmosphere, the temperature is -49 C. Speed of sound is 583 knots. Your minimum true airspeed for sustained flight would be 111 knots or 10 indicated. At 90,000 feet, 111 Knots is Mach 0.19 which is greater than your maximum Mach number of 0.16. This theoretical glider cannot maintain level flight at 90.000 feet.

    Solving this problem requires an airframe with a very large ratio between minimum and maximum airspeeds. Most conventional airplanes have a ratio of about three to one. Our example had a ratio of 11 to 1. This is where the U-2 reaches its limit and am told the min and max speed are very close at high altitude. The SR-71 solved this problem by increasing the maximum speed, but the tradeoff is a greater minumum airspeed due to the increased weight. It is critical that the tradeoff leads to a greater ratio of max to min airspeeds.

    Doing it at the other end, reducing the minimum airspeed, would be much more challenging, because you would need to design a structure that can fly at very low speeds, but still have the aerodynamic stiffness and strength to be safe at higher speeds up to around Mach 0.2. It might be possible, but is definately not easy. I'm not aware of any manned fixed-wing aircraft that can fly as slowly as 10 knots and still have maximum speeds in the 100 kts range.

    Critical mach number can be a problem in conventional sailplanes when they get above about 20,000 feet. The pilot needs to be aware that flutter will begin at lower indicated airspeeds than the red line on his airspeed indicator. I would leave 90.000 feet to either a U-2 or an unmanned model airplane. I do not think it is practical in an amateur-built experimental glider attempt to fly that high. But I am sure somebody will attempt it.

    • This is what happens when a glider exceeds the maximum airspeed V_ne: How to break a gliders wing [youtube.com].
      • Actually, that particular aircraft (Darmstadt D36) was one of the first fibre glass ships, and suffered the flutter due to excessive flexibilty in torsion of the wing skins.
        These days, a lot more is known about layups and materials.
        One of the student designers at the Akaflieg, Gerhard Whaibel, (since a world famous designer for Alexander Schleicher) famously accidently spun the d36, and standard recovery did not work, instead, he violently rocked the ailerons, causing the wings to flex and managed to recove

    • Ive never flown a modern sailplane with a VNE less than 135kt, several have been 140, and one 155.
      In recent times, special high VNE gliders have been made to fly records in the Andes, in some cases the record is higher than the original VNE.
      The Perlan 2 has a pressurised cockpit, and is designed for the necessary loads and speeds.
      Further, flying in wave is VERY smooth, no sensation of motion at all.
      Speed control will be an issue, as they will be in coffin corner at high altitude.

  • I'm not an aeronautics expert but isn't there a huge risk of snapping the wings off the glider? When you get close to space there's not much air which means the glider will essentially reach freefall and hit terminal velocity. The real problem is when it re-enters atmosphere you go from no wind resistance to wind resistance that shock could rip the glider apart. Hope they have an expert on their project. The "safest" way is to try to nose dive the glider until it reaches enough atmosphere for the wings

Q: How many IBM CPU's does it take to execute a job? A: Four; three to hold it down, and one to rip its head off.

Working...