altitude   292
Consequences of a living on a sphere
Because the World is not flat, you can’t see forever. As you look out to the horizon the planet falls away from you. This limits what you can see.
An adult person of around 6 ft tall has eyes approximately 1.8 m above the ground (yes, I'm using the Metric system). For the radius of the Earth, I'm going to use the value 6,371 Km (the mean radius). ... The solution is that the furthest an adult can see is 4.79 Km (which is just short of 3 miles).

The top observation deck of the Eiffel Tower is at 273 m.
From this altitude, the horizon will be 58.98 Km away (36.65 miles).

The top floor of the Burj Khalifa tower in Dubai is 621 m high.
This would give a viewer a theortical view over the desert of 88.96 Km (55.28 miles).

An airliner cruising at 38,000 ft is at an altitude of 11.58 Km
Plugging this into the formula reveals an answer of 384.3 Km, which is 238.8 miles.

When we were dealing with small altitudes, the difference between the straight line distance, and the ground distance along the curve of a planet was insignificant. Let's calculate the delta between these two distances for our cruising aircraft.
For a plane at high altitude, the difference between the straight line distance to the horizon and the curved distance on the Earth is about 500 m. (The difference when dealing with our first example of a man of height 1.8 m is a fraction of a millimeter).

The Golden Gate Bridge, possibly the most photographed bridge in the World, spans the opening of San Francisco Bay. Completed in 1937, it boasts two towers of height 230 m and these are 1,280 m apart. The top of the Golden Gate Bridge is almost two inches wider at the top than the base because of the curvature of the Earth!
distance  horizon  propagation  sphere  aircraft  airplane  altitude  geometry  trigonometry  Pythagoras
december 2018 by Tonti
[1803.03111] Steam balloon concept for lifting rockets to launch altitude
So ground filled steam balloon might not suck at larger sizes, for rockoons?
steam  lift  gas  high  altitude  balloon  rocket  launch  rockoon  space  research  technology
november 2018 by asteroza
Ball Aerospace - OAWL- wind LIDAR
New compact wind LIDAR with long range, which in theory would allow a high altitude balloon to detect favorable wind directions and change altitude to maneuver, becoming effectively stationary.
wind  detection  LIDAR  DARPA  high  altitude  maneuvering  geostationary  stratellite  balloon
november 2018 by asteroza
Ascent to Altitude as a Weight Loss Method: The Good and Bad of Hypoxia Inducible Factor Activation
> Disease states such as chronic obstructive pulmonary disease and cancer are conditions where there is a persistent loss of appetite with an increase in energy expenditure. Another situation in which weight loss is accompanied by appetite suppression and increased energy expenditure is when otherwise healthy subjects are taken to altitude. While the cause of weight loss in chronic obstructive pulmonary disease and cancer is complex and multifactorial, a feature these diseases share in common with normal subjects exposed to altitude is hypoxia (1). At altitude hypoxia is secondary to the reduction in barometric pressure causing a decrease in the inspired partial pressure of oxygen whereas hypoxia is due to parenchymal lung injury in chronic obstructive pulmonary disease. Hypoxia in cancer patients is more localized and results from tumor growth outstripping its vascular supply (2).

This review will examine the physiologic response to hypoxia and focus on those mechanisms which may contribute to weight loss in these otherwise disparate conditions. Several points will be emphasized. First, hypobaric hypoxia facilitates weight reduction not only by suppressing appetite but also by increasing energy expenditure. Second, up-regulation of hypoxia inducible factor (HIF) mediates the loss in weight, change in energetics, and
weight_loss  altitude  cancer  HIF  hypoxia
october 2018 by porejide
Adjusting Cabin Pressure Eases Air Passenger Discomfort - ABC News
“Most aircraft cabins are pressurized to 8,000 feet above sea level, an altitude that lowers the amount of oxygen in the blood by about 4 percentage points, researchers say.

“This decrease in oxygen saturation isn’t enough to bring on acute mountain sickness, but pressurizing the cabin to 6,000 feet could help some passengers feel better when flying, concludes a study in the July 5 issue of the New England Journal of Medicine.”
planes  pressurization  travel  2018  altitude
october 2018 by handcoding
Development and Experimental Validation of a Hall Effect Thruster RAM-EP Concept
Air breathing electric hall thruster concept for low orbital altitude satellites to maintain speed. Not a PROFAC air scooper per se, since this uses all inlet air for thrust. Beehive inlet as well.
PROFAC  low  orbital  altitude  drag  compensation  air  breathing  hall  effect  electric  thruster  space  propulsion  aerodynamics  research  technology  ramscoop  beehive  inlet
april 2018 by asteroza
Conceptual Design of an Air-Breathing Electric Thruster
Seems beehive-style inlets for air scooping at low orbital altitudes are in.
PROFAC  low  altitude  orbital  atmospheric  gas  scoop  ramscoop  inlet  design  aerodynamics  space  research
april 2018 by asteroza
Google Maps - Find GPS coordinates, longitude, latitude, altitude
Use this tool to find and display the Google Maps coordinates (longitude and latitude) of any place in the world.
NEW: Now we even show the sea level/elevation of the marked position!
march 2018 by jmi
The Global Airport Database
MIT Licensed global airport information. Not clear how often it is updated.
aviation  airport  location  altitude
november 2017 by drmeme

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