Sigma Rockets

Mercury Atlas with Friendship 7

The four hour and fifty-six minute flight around the world inside a tiny Mercury capsule named Friendship 7 was anything but routine for the brave American astronaut.

Historic Flight

On February 20th, 1962 a highly decorated captain in the United States Marine Corps named John Glenn became the first American to orbit earth. His Mercury capsule named Friendship 7 orbited the planet three times in almost five hours before returning home.

The successful launch was at a crucial moment in the early years of the space race against their rival and other world super power the Soviet Union. Russia had already launched two cosmonauts into orbit beginning with Yuri Gagarin on April 12th, 1961 and Gerhman Titov on August 6. Titov orbited the earth for an entire day.

Meanwhile NASA in the United States had only sent astronauts Alan Shepard and Gus Grissom on sub-orbital flights. They were launched into space using the short range Redstone rocket designed by the German engineer Wernher von Braun. The more powerful Atlas rocket which would later fire Glenn into orbit was still being tested.

The Beginning of NASA

The National Aeronautical Space Administration opened its doors in October 1958 when President Eisenhower decided a civilian agency should lead the country into space. The United States Air Force and the army had been squabbling for years over who should have jurisdiction over it.

In 1957 the Soviet Union launched the world’s first man made satellite ‘Sputnik’ into orbit. Many believed Eisenhower’s wait for a non-military rocket cost the United States the glory of reaching space first. Eisenhower eventually let the army launch a modified Jupiter army rocket into orbit. This rocket named Juno 1 was designed by the famous rocket scientist Werner von Braun. The launch put America’s first satellite, Explorer One into orbit on January 31st, 1958.

JFK Chooses the Moon

By the time Glenn was preparing for his historic flight in 1962, the Eisenhower administration was out of the White House. A younger more adventurous president named John F. Kennedy took over. President Kennedy was determined to make up for all the ground he felt was lost to the Soviets since World War II had ended. JFK, as he was known, famously set his sights on the moon.

Nevertheless, before the moon could be reached the United States would first have to orbit the earth. This was going to be up to forty year old John Glenn. His Atlas rocket had experienced some highly publicized explosions since the first test flights in 1957. This made the astronauts a feel a little bit uneasy.

John Glenn climbs into Friendship 7 before his historic flight

The Mercury Seven

The Ohio native was undeterred however. Glenn had been selected in 1959 along with six other test pilots from different branches of the military to become America’s first astronauts. Glenn was the only one from the Marine Corps. The Mercury Seven, as they became known, would ride into history on-board dangerous rockets carrying thousands of pounds of explosive fuels. These rockets tended to blow up during testing more often than the engineers would have preferred. “Our rockets always blow up and our boys always botch it” was a classic line from Tom Wolfe’s novel and Hollywood movie “The Right Stuff” chronicling the Mercury Seven program.

After two months of delays and already ten scheduled launch postponements the Atlas rocket finally ascended from pad 14 at 9:07 am local time on February 20th, 1962 from Cape Canaveral in Florida. Inside the 4,265 pound Mercury capsule, named Friendship 7, was John Glenn. He squeezed himself into a custom made seat. His spacesuit was just as silvery and shiny as the rocket he was riding on. Over the roar of the three liquid fuelled engines the words Scott Carpenter’s words of “God speed John Glenn” echoed through the capsule communicator. The seventy-five foot shining aluminum rocket performed perfectly on take off. The black Mercury capsule perched on top separated as planned from the Atlas booster five minutes later. NASA was aiming for seven orbits. Things were going well early on.

John Glenn Takes Control

Soon after, however, Glenn began encountering problems. During the second orbit a thruster to help control Mercury’s attitude was not working properly. Glenn was immediately forced to go from ‘fly by wire’ to manual control. There were eighteen of these tiny thrusters around the outside of the capsule fuelled by hydrogen peroxide controlling the pitch, roll, and yaw. Glenn had to constantly make manual adjustments to the drifting space capsule causing the thruster fuel to drain faster than expected. This was vital because Glenn needed some fuel to make last minute manoeuvres for the return home. The process involved an important attitude correction making sure the heat shield was facing down and on the proper angle during re-entry. Glenn was able to manage the situation on his own through manual control. It wasn’t long however before the astronaut received more unsettling news from mission control. This time from where he was sitting there was nothing the marine fighter pilot could do about it.

Harrowing Re-entry

A flashing light on a lone panel somewhere in the control center indicated that the landing cushion had deployed and possibly loosened the heat shield. The heat shield was the last and only line of defence protecting an astronaut from the extreme temperatures faced during re-entry through earth’s atmosphere. Flight Director Chris Kraft was certain the light was a false reading and opted to jettison the retro pack as planned when re-entry commenced. On launch day the Flight Director is always in charge. On this day though, Walt Williams, the Operations Director and Kraft’s boss was standing in the back of the room and disagreed with the Flight Director’s decision.

Williams suggested the retro pack remain attached to the bottom of the capsule for Glenn’s entire way down. He argued that the same metal straps holding the rocket pack into place would also secure a loosened heat shield as well. The retro pack was hopefully going to burn up through the atmosphere without giving any problems to the capsule. The pack was usually discarded as soon as the retrograde rockets did their job and the capsule began descending from space. Kraft was concerned that if the pack was left on and there happened to be trace amounts of hydrogen peroxide fuel left over in any of the small retro engines it could cause an explosion.

There was also the worry that not all of the retro pack would burn up as planned during its descent and parts could break off and damage Friendship 7. Glenn was not happy when he heard the change of flight plan so late in the mission. It was customary in the military for a test pilot to receive any and all information regarding his troubled aircraft as soon as a problem occurred. This was not done and NASA made the decision to keep the problem from Glenn until the very last minute. It had concerned them enough they shortened Glenn’s trip to just three orbits. As well a phone call between the astronaut and President Kennedy which was supposed to take place on one of Glenn’s passes over the United States was cancelled.





To break away from orbital speed and return to earth earlier than he had wished, Glenn fired his control rockets one at a time to position the craft for re-entry. The capsule’s blunt end where the heat shield was attached received temperatures in excess of 3000 degrees Fahrenheit for several minutes. This is the black out period between the astronaut and mission control when radio signals are absorbed by the fireball surrounding the craft and communication is not possible. Through his small window Glenn witnessed charred remains of the retro-pack bang up against the sides of Friendship 7. He continued to report in to the control centre even though it was impossible for them to hear him. He was on his own and would later comment that he actually enjoyed the peace and quiet. “Cautious apprehension” were the words used by Glenn himself describing his true feelings through the anxious minutes before the drogue chute finally deployed at 22,000 feet. Mission control along with the entire country waited nervously on the ground for Glenn to report in.

JFK inspects Friendship 7

A Safe Landing

The Mercury Capsule’s massive orange and white striped main parachute sprung open above Friendship 7 at 10,000 feet over the Atlantic Ocean. Soon after the landing bag deployed on time and inflated around the capsule without any problems. Kraft ended up being right, it was a false alarm. After three orbits around the earth and back John Glenn and his Friendship 7 capsule had travelled 81,000 miles in just 295 minutes. Glenn was down to fifteen percent fuel in his manual tank when he hit the water. He had flown most of the flight on his own. Astronauts were no longer “spam in a can” as renowned World War II pilot Chuck Yeager once professed.

Friendship 7 undershot the predetermined splash down point in the Atlantic Ocean by 40 miles while ending up 800 miles south east of Bermuda. This was just 500 miles from where he lifted off from at the Cape. When the USS NOA arrived to retrieve the capsule it was gingerly bobbing up and down in the water with the American astronaut safely inside. On-board the recovery ship Glenn finally received his much anticipated call from President Kennedy with congratulations over the radio-telephone.

A Hero’s Welcome

John Glenn received a hero’s welcome on his return to the United States. When Glenn arrived in New York on March 1st over four million people lined the streets of Manhattan for the largest ticker tape parade in New York City history. Because of Glenn’s successful trip around the world and back the American space program quickly moved forward. It was now at least equal with the Soviet program. The Mercury flights would come to an end in 1963 after Gordon Cooper successfully orbited the planet twenty-two times on May 15th.

Life After NASA

Six weeks following President Kennedy’s assassination in Dallas on November 22nd, 1963, John Glenn resigned from NASA and the space program to pursue his love for business and politics. In 1975 Glenn was elected the Democratic Senator for his home state of Ohio. In 1998, at the age of 77, he flew on-board the Space Shuttle Discovery, becoming the oldest person to travel in outer space. Friendship 7 remains on display in the Smithsonian Air and Space Museum in Washington, DC. The heat shield is still firmly in place.

Fifty years later Glenn’s flight is regarded in historical ‘Cold War’ terms as the launch that put the United States back on course in the space race with the Russians. The Gemini and Apollo programs succeeded Mercury. This lead to Neil Armstrong’s legendary date with the moon in 1969.

But first it was John Glenn in 1962 and his three orbits around our planet in a Mercury capsule that paved an invisible flight path to outer space for future American astronauts like Armstrong.

“This is the new ocean, and I believe the United States must sail on it and be in a position second to none.”
-President Kennedy immediately following John Glenn’s return to Earth in Friendship 7.

About John Glenn

• Born: July 18th, 1921 in Cambrigde, Ohio
• Education: Bachelor of Science degree in Engineering from Muskingum College, Ohio.
• Glenn was commissioned in the Marine Corps in 1943.
• In July 1957 Glenn set transcontinental speed record in F8U Crusader from Los Angeles to New York in 3 hours and 23 minutes.
• John Glenn joined NASA in 1959 as part of the Mercury Astronaut Program.
• On February 20th, 1962 Glenn piloted the Mercury/Atlas 6 flight.
• In 1975 Glenn was elected Democratic Senator for Ohio.
• On October 29, 1998 Glenn flew on-board the STS-95 (Space Shuttle) at the age of 77 years old.
• On July 18, 2011 John Glenn celebrated his 90th birthday. Glenn and Scott Carpenter are the last living members of the Mercury Seven.

About the author

• Wilfred Ashley McIsaac is a graduate of the Toronto School of Business and now writes freelance articles concentrating on historical achievements in space. McIsaac has flown high-powered rockets in Canada since 1997 and recently launched a rocket in Gananoque, Ontario carrying mail addressed with 75 year old ‘First Canadian Rocket Flight’ stamps. Video of the flight was a success on YouTube and the Sigma Rockets website and may be viewed here.

©2012 Sigma Rockets and Aerospace Inc.

There are a few ways to determine the altitude of your rocket. In a previous article we discussed using inclinometers and trigonometry. In this article we will discuss using electronic altimeters for model rockets to measure the altitude of flights.

Figure 1 - Basic Pressure Altimeter

Using Electronic Altimeters for Model Rockets

The most common electronics device carried aboard rockets are electronic altimeters. In recent years, electronic altimeters have become more and more plentiful and as a result less expensive than when they were first introduced. As well the size of the altimeter has decreased significantly adding as little as 6 grams of weight to the rocket.

Altimeters employed in rocketry may be used to control the ejection charge. But most of all they are used to measure the apogee, or highest altitude, achieved in a flight. Simple altimeters indicate measurement through a series of beeps. Some altimeters may be connected to a computer for data extractions. Still other use a small display screen on the altimeter itself to indicate measurements taken. Figure 1 shows a simple altimeter that relays the apogee of the flight through a series of beeps.

To measure altitude either of two basic methods are employed: measuring acceleration or measuring air pressure.

Pressure Altimeters

Pressure altimeters use atmospheric pressure to determine altitude. The lower pressure high above the ground is compared to ground level in order to determine the altitude.

Sealed aneroid (defined as using no liquid) wafers are exposed to outside air and the pressure difference causes the wafers to expand or contract. This change is then measured and used to determine altitude.

Figure 2 - Installing an altimeter into an electronics bay

Pressure altimeters must measure the outside air. Thus vents (holes) must be made in the rocket or the payload section holding the altimeter. Pressure altimeters may also be affected by pressure fluctuations on rockets that reach speeds in excess of Mach 1 (the speed of sound) and low pressure caused by weather. However, modern pressure altimeters take these factors into account and adjust for it. For example, some altimeters will not measure altitudes of less than 15 meters or 50 feet to account for low pressure due to weather.

Accelerometer Altimeters

Accelerometer altimeters measure the change in velocity (the acceleration) of the rocket. By knowing this and the time, accelerometer altimeters are then able to determine the apogee of the flight.

These type of altimeters do not need to be vented to the outside air. However, they are less accurate when the rocket does not fly perfectly straight.

Dual Deployment

For bigger or high-power rockets, altimeters may be used to control the ejection charge used to deploy the parachute. Often this involves having two ejection charges fired, one for pushing out a drogue parachute and the other for deploying the main parachute. By pushing out a drogue the rocket is positioned such that it is falling horizontally. This keeps the rocket from picking up too much speed in descent and allows the main parachute to be fired out sideways and not down.

Figure 3 - Altimeter Data

Dual deployment allows for more accurate landings as the main parachute is fired at a relatively close altitude to the ground. This cuts down on drift significantly. Multiple altimeters are often used in dual deployment systems. Usually the altimeters come from different manufacturers. This cuts down on the risk of an altimeter not firing due to sensitivities based on manufacturer. Dual deployment altimeters are often installed in a separate payload bay. Figure 2 shows such an installation.

Measuring More Than Altitude

As mentioned above, some altimeters may be used to measure more than just the apogee of the flight. Some altimeters, such as the Entacore AIM USB altimeter, have USB connections that allow their data to be extracted to a computer and displayed graphically (see figure 3).

Figure 3 is a extraction of data from a rocketry flight using this altimeter. As the AIM USB altimeter is used for dual deployment in high-power rockets it may be configured for deployment times using the computer program provided.

Through the use of its small LCD screen the Altimeter Two from Jolly Logic is able to give flight measurements such as top speed, engine burn time, ejection altitude, coast time to apogee, descent speed, peak and average acceleration, apogee to ejection time and the total flight duration.

Additional uses for altimeters

Altimeters that offer more than just the altitude may often be used in non-flight applications. For example, how about taking one on a roller coaster ride! That first drop may provide some interesting data. Measuring velocity, acceleration, and height are valuable parameters to have for interesting classroom discussions.

Purchasing an Altimeter

Careful research should be taken to determine the altimeter that is best for your application. Factors such as cost, functionality and size may be considered.

In the case of dual deployment altimeters, care must be taken to choose one with a good reputation as a failure of a dual deployment altimeter could prove tragic. Quite often redundancy in the form of multiple altimeters and timers is employed in a high-power rocket to reduce the risk. We currently do not carry dual deployment type altimeters in the Sigma Rockets Online Store.

Below I have listed two altimeters, Altimeter One and Altimeter Two from Jolly Logic, that we currently do offer. Altimeter One provides a simple way to measure and display apogee of a flight and Altimeter Two offers more flight analyses as described above. These have a protective casing to cover the circuit board instead of exposing it as most altimeters do. Please note however, that despite looking like USB memory sticks, the altimeters use the USB connection merely for charging their internal batteries and do not transfer flight data to the computer. Flight data is displayed through the use of their LCD screens.

The Altimeter ONE measures peak flight altitude and may be used for rockets, planes and kites.



Price: $49.99 CAD Display: LCD Size: 12mm X 16mm X 49mm Weight: 6.7 grams Useful Range: 15 to 9000 metres above sea level Charging: Internal battery charged by USB port The Altimeter TWO is designed exclusively for rockets and measures top speed, engine burn time, ejection altitude, coast time to apogee, descent speed, peak and average acceleration, apogee to ejection time and the total flight duration. Price: $68.99 CAD Display: LCD Size: 12mm X 16mm X 49mm Weight: 6.7 grams Useful Range: 15 to 9000 metres above sea level Charging: Internal battery charged by USB port

©2012 Sigma Rockets and Aerospace Inc.

OpenRocket

The ability to design and test your rocket before actually building it is quite the asset for the rocket designer. Many programs exist for this. One of these programs is the Java-based open source software named OpenRocket.

About OpenRocket

OpenRocket features realistic wind modeling, clustering and staging, just to name a few. It allows for free-form and canted fins. OpenRocket is an Open Source project licensed under the GNU GPL.

This means that the software is free to download and to use for whichever purposes you desire. You do not need to purchase or register for a license code to use this software.

As well the source code is also available for studying and extending. So for those of you that are Java programmers, OpenRocket source code may be downloaded and modified to suit your purposes.

Downloading and Running the Program

As with many software programs the best way to learn it is to give it a try. You may download OpenRocket from the download page here.
OpenRocket is hosted on the SourceForge network and you may visit the website of OpenRocket by clicking here. To use the software download the latest version and double click on it. It will come as a jar file. You will need the Java runtime library installed on your computer. You may download java from the java.com website by clicking here.

You may run OpenRocket on Windows, Linux, Mac OS X or any other operating system that supports the latest Java Virtual Machine. For those of you using Mac OS X you may not need to download Java as the latest version should be installed with the Operating System.

Please note however I was not able to run OpenRocket on a G4 Mac running Leopard. I didn’t have a problem with an Intel based Mac running the same OS. This is due to the fact that the version of Java needed for OpenRocket (the latest version) is not available for non-Intel Mac computers.

Getting Involved

As OpenRocket is an open source project there are opportunities to get involved with the development, testing and documentation of the program. As of this writing the project is currently looking for Java Developers, people to assist with aerodynamic computation methods and people to help write the documentation. Getting involved would be an excellent way to not only improve the program but to help you in your aerospace education.

For more information on OpenRocket please visit the website at: http://openrocket.sourceforge.net.

©2011 Sigma Rockets and Aerospace Inc.

Rockets are a useful tool for many pursuits ranging from educational tools to placing communications satellites into orbit. However, there is one use that has been brought up time again over the years and that is for the delivery of mail. That’s right, delivering mail through the use of rockets, or rocket mail for short. In this article we will discuss this concept.

Image: The Canadian Aerophilatelic Society Library

The History of Rocket Mail

In 1931 Friedrich Schmiedl launched the first rocket with mail in Austria. The rocket carried 102 pieces of mail for 400 kms between two Austrian towns. He followed it up with a flight that carried a spectrograph along with the mail. Special postcards were printed after the flight to commemorate this achievement.

In the 1930s as well, a man by the name of Gerhard Zuker displayed his mail carrying rockets throughout Germany. He also attempted to convince the postal service in the United Kingdom of the viability of rocket mail. Zuker continued his attempts to validate rocket mail technology with flights across the North Sea. Despite his determination rocket mail never caught on.

Around the same time in India, Stephen Smith the Secretary of the Indian Airmail Society experimented with 270 rocket mail flights. He was successful in sending rocket mail over a river as well as delivering a parcel.

Successful rocket mail flights occurred in the United States in the 1930s. In 1959 the US Navy submarine, the USS Barbero implemented “missile mail” services for the American Post Office Department. This was accomplished through the use of cruise missiles converted to carry mail instead of a nuclear warhead. Excitement over the future of rocket mail built up however, many in the US Defense Department simply saw it as a demonstration of their missile capabilities. The cost of using these cruise missiles for the purpose of delivering mail could not be justified.

Further rocket mail flights occurred with the launching of mail carrying missiles from Russian submarines. As well, rockets launched from Fort Churchill in Manitoba, Canada carried mail. The flights at Fort Churchill were mainly done to gather scientific data. The mail carried aboard was just for demonstration. The impact of the rocket on the ice of Hudson Bay upon re-entry destroyed the mail.

Amateur Rocket Mail flights

In the 1950s amateur rocket fliers began to fly rockets carrying mail. As we discussed in one of our articles last year post cards addressed to Pierre Trudeau and the Queen were flown aboard a model rocket in 1972 in Ottawa.

These flights are generally symbolic as the mail flown in them is retrieved close to the where the rocket was launched. The mail is then dropped into a mail box where it is delivered through the postal service.

The Future of Rocket Mail

Due to the high cost of launching rockets accurately the future of rocket mail does look dim. Still the idea of launching a parcel or a payload of letters in a rocket through the air at high speeds reaching their destination in a matter of minutes will continue to fascinate many. Rocket mail will surely continue to live on in science fiction especially in the realm of retro-futurism.

Ashley McIsaac and Canadian Rocket Mail

Below we have an embed of a video shot and edited by Ashley McIsaac of Ontario, Canada. Ashley launched mail aboard a rocket recently believing the attempt to be the first flight of rocket mail in Canada. Although it was not the first it is certainly a very entertaining video to watch as an on-board video camera is used to record the flight. In the payload section of the rocket were letters with Canadian rocket mail stamps from produced by German Gerhard Zucker in 1936. Additional stamps were used to top up the amount. After the flight, three of these letters were cancelled at the post office making them symbolically delivered by rocket mail. We would like to thank Ashley for his video.

©2011 Sigma Rockets and Aerospace Inc.