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Students' Experiments To Fly By Glider To the Edge of Space
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.
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.
For those struggling to understand the title:
Glider to fly students' experiments to the edge of space.
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.
Well, except ICAO, which sets aviation standards, measures altitude in feet, airspeed in knots-per-hour, and you even set your altimeter in INCHES of Mercury.
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 boys. We have one team exclusively made up of young ladies. Three student leads and five teachers are women. The teams range from college to kindergarten.
- We dream of the stars. Now let us return to them.
The edge of space is 328,000 feet (100km). They're only going up 90,000 feet. That's less than a third of the way. "Oh, look! I'm on the second floor. I'm on the edge of space!"
When our name is on the back of your car, we're behind you all the way!
The edge of space is 328,000 feet (100km). They're only going up 90,000 feet. That's less than a third of the way. "Oh, look! I'm on the second floor. I'm on the edge of space!"
You gotta admit, it's the biggest argument for the metric system when the boundary of space is right at 100 km!
Regardless of my lame joke, this is reminiscent of the high altitude balloon launches performed by schools along with Radio Amateurs. These activities are a lot of fun as well. Teaches the kids a lot about working in teams, solving engineering issues in packaging, payload constraints, tracking, and working within regulations.
And maybe one of these kids will figure out a better way of getting amateur science higher than the second floor.
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
All the science is done in metric. The experimental frame is a 10cm cube. The final mass is under 1 kg. All altitude and temperature data is metric. 90,000 feet is something the public can relate to.
- We dream of the stars. Now let us return to them.
Well, we ran it only as a science inquiry project. The judges were only given the grade of the students and their research application. All other identifying data was removed. Ten groups made the cut based on the strength of their work and nothing else. While it seemed the best approach, maybe things would have been better if we first pre-selected the winners based on socially acceptable moors and then worried about the science. Thanks for pointing out the error of my ways. :)
- We dream of the stars. Now let us return to them.
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.
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 to generate lift and then to pull up carefully?
I fly gliders in Europe and we use metric on gliders. Very convenient indeed :)