Monday, April 26, 2010

Machu Picchu

Machu Picchu is an ancient city located in Peru. Meaning “Old Peak” in Quechua, the native language from the Inca Empire, this mountain relic is claimed as one of the new Seven Wonders of the World. The city draws its popularity not from what lies within its walls but where it was built, 2,430 meters (7,970 feet) above sea level.

The city is believed to have constructed around the 1450. Yet scientific research has shown that it was abandoned a little more than a century later, synonymous with the arrival of the Spanish Conquest. Historians speculate that the city’s population had succumbed to an outbreak of smallpox before the Spanish’s arrival.

Most archaeologists believe that Machu Picchu was built in honor of the great Inca emperor, Pachacuti (1432-1472). Others hypothesize that its purpose was to govern the economy of nearby settlements. Located on a mountain top, its inhabitants would have had a good view of their surroundings. Smaller minorities believe the city had a more simple purpose such as a prison or an agricultural testing station that would test how different types of crops survived in the variable climate.

The city sits in a valley between the two larger mountains Machu Picchu and Huayna Picchu. Early settlers would have received water from nearby springs while food would have been grown from local fields. It’s actually interesting, because there is enough land to feed four times what the city’s population at the time. Engineers also terraced the surrounding hillsides to guard against invaders and reduce soil erosion to prevent landslides.

 aerial shot of Machu Picchu

One of the area’s leading tourist attractions is the Intuhuatana Stone. A rare ritual stone found in South America, the rock is arranged to point directly at the sun during a winter solstice. This results in no shadow casted by the leading pillar during the equinoxes. It’s speculated the device was a primitive calendar.

Did you know?- There are many flights of stairs at the city consisting of one hundred steps or more carved from a single block of granite!

The important buildings inside Machu Picchu have polished-dry stone walls made with a technique called ashlar in which precision cut stones are fitted together tightly without mortar. Peru has a lot of seismic activity and the structure’s walls can shift and resettle without collapsing.

Wednesday, April 14, 2010

Human-powered Flight

While we have shared the sky with birds for the last hundred years, modern flight continues to leave many feeling disconnected from the winged creatures. My opinion for this happening is that while birds experience flight firsthand, we are simply trying to mimic their grace. Before the choice to use an external power source was even an option, man could only dream of attaining flight through our own human efforts. And with engine-powered flight now available for personal use to everyone in the planet, the idea to lift one into the heavens has lost much steam. Only a few have achieved what Icarus did in the story.

Human-powered aircraft (HPA) are propelled by only human force and gravity. In this way, they rely on many of the same principles as gliders such as air thermals and rising currents. The first recorded human-powered aircraft was the Italian designed Pedaliante (Italian for “Pedal Glider”) in 1937. Constructed with a glider-like profile, the plane had a wingspan of 58 feet (17.7 meters) and two laminated balsa wood propellers 6.2 feet (2 meters) in diameter. The plane had an aspect ratio of 13:4 meaning that for every 13 feet it traveled horizontally, it only descended 4 feet. The sole pilot sat upright and transmitted power to the props via pedaling.


While originally the plane was to have an empty weight of 160 pounds (73 Kg) the Italian Air Ministry required it to meet the same structural criteria of an engine-powered aircraft increasing its final weight to 214 pounds (97 Kg). Launched with the assistance of a catapult, the plane came to travel a length of 1 Km (0.62 miles), remarkable for its time.

It wasn’t until 1960 that a man-powered aircraft capable of taking off under its own power was created. That year’s spring, three undergraduate students at Southampton University decided to build an HPA during the middle of their last term. Duly named the Southampton University Man Powered Aircraft (SUMPAC), the plane would complete over 40 flights, the longest of which was 2,130 feet (650 meters).


Since the 60s, there have been a number of HPAs. And while each new design comes closer to the goal of easily sustained, long-distance flight, we’re still not there yet. Today, the world record for longest human-powered flight is 74 miles (119 Km), achieved on April 23, 1988 by the MIT Daedalus 88. The design only weighed 69 pounds (31 Kg).

MIT Daedalus 88

Did you know?- The first human-powered helicopter, the Da Vinci III, built by the California Polytechnic State University in 1989, flew for 7.1 seconds reaching an altitude of 20 centimeters. The video below showcases a later design, the Yuri 1, constructed in 1994 that utilizes four giant rotors.