The 50th Flight of the Falcon 9

Awe inspiring Falcon 9 Photo
A truly awe inspiring photo Of the Falcon 9’s 50th flight. From the SpaceX Flickr.

At 05:33 UTC on March 6th 2018 SpaceX launched it’s 50th Falcon 9 mission. The version 1.2 Falcon 9, with a brand new “Block 4” variant booster B1044, lifted off from Cape Canaveral Space Launch Complex 40. On board, inside the type 1 fairing was Spain’s Hispasat 30W-6. Weighing in at 6,092kg, being the size of a bus and being launched into geosynchronous transfer orbit, it’s the biggest challenge that the Falcon 9 has come up against.

50th Falcon 9 Flight 1
50th Falcon 9 flight soars into the Florida night sky, Image by @marcuscotephoto on Twitter

The First stage if the Falcon 9 fired for about 2 minutes and 35 seconds before releasing and plummeting back towards the Atlantic ocean. The initial plan was top land the “type 4” first stage on the autonomous drone ship “Of Course I Still Love you” in the Atlantic. Landing legs and titanium steering grid fins were attached and went up with the rocket.  There was already speculation, due to the large payload and the orbit attempted, whether the Falcon 9 would have enough fuel left to attempt the reentry and landing procedure. Unfortunately it was not possible to find out whether the F9-51 mission would have made a landing because the autonomous drone ship was kept in port because of high sea conditions. The rocket still went through the entire reentry and landing procedure, as mentioned on the livestream, but ended up in the Atlantic.

Long exposure of Falcon 9
An awesome long exposure shot of the Falcon 9 Taking off from SLC-40. From @marcuscotephoto on Twitter

almost 9 minutes in, the second stage with the payload achieved a Low Earth Orbit, and “parked” until T+26 min 36s where they first crossed the equator. This second burn lasted 55 seconds to accelerate the ss/Loral-built satellite  into a Geosynchronous Transfer Orbit. The Hispasat 30W-6 will fire its four SPT-100 plasma thrusters to gradually raise itself to Geosynchronous Orbit positioned 30 degrees West (clue in the name). Hispasat 30W-6 is designed to provide broadband services in Europe and Northwest Africa.

The Hispasat 30W-6 launching
The Hispasat 30W-6 launching at night, from SLC-39. From SpaceX Flickr.
Timelapse of Falcon Launch
Timelapse of Falcon Launch from across the water, from SpaceX Flickr

This is the fourth all-expendable Falcon 9 launch in the past 5 years, and the first time a “type 4” stage has been expended on it’s first flight. Both of the stages of the F9-51 rocket were tested at SpaceX Rocket Test Facility in McGregor, TX during October/November 2017. They have been at Cape Canaveral since January 2018, and were stacked ,loaded with propellant and tested (first stage only) at the Cape at SLC 40 on February 20, 2018. The Launch was initially planned for February 25th, but was shelved by SpaceX to investigate payload fairing pressurisation issues.

Raw power of Falcon 9
An image showing the raw power of the Falcon 9, from SpaceX Flickr.

The Latest Atlas V Launch GOES-S Well

The Atlas V launch
The Atlas V launch taken by @marcuscotephoto on twitter.

At 22:02 UTC on March 1st 2018 the Second Atlas V launch of 2018 fired the 5,192kg GOES-S satellite into orbit. Launching from Space Launch Complex 41 at Cape Canaveral, FL, the AV-077 (the launch designation) was an Atlas V in 541  configuration. GOES-S, an A2100 series satellite built by Lockheed Martin, was separated 3.5 hours into the mission into a 8,215km x 35,286km x 9.52 deg Geosynchronous Transfer Orbit (GTO).

Atlas V launch
Atlas V launch from Launch Complex 41 at Cape Canaveral, FL. Image from @NOAASatellites Twitter.

The second of a new generation of weather satellites for the United States, GOES-S follows in the footsteps of GOES-East, now renamed to GOES-16. A huge jump in satellite capability, the new set of satellites cover from eastern Japan all the way over to west Africa, as well as parts of the Arctic and Antarctic. They can detect storms faster, see lightning and even have sensors to detect solar storms. The satellites were commissioned by the National Environmental Satellite, Data and Information Service (NESDIS) who manage the National Oceanographic and Atmospheric Administration (NOAA) constellation of environmental satellites. For more images and information follow them on twitter @NOAASatellites.

The new generation of weather satellites
Image showing the difference between GOES-16 and the previous version, GOES-13. Image from @NOASatellites twitter.

There are versions of the livestream on Youtube, and a highlight reel on the ULA Youtube page. They are definitely worth a watch if you want more information from the engineers themselves.

Atlas V launch
Atlas V launching the GOES-S satellite on March 1st 2018. Image from @NOAASatellites Twitter
The Atlas V just taking off
The Atlas V just taking off, Image from @NOAASatellites

To find similar photos, and to buy reasonably priced prints of some of the above visit www.marcuscotephotography.com

The Ups And Downs Of The Falcon Heavy Launch

At 20:45 UTC on the 6th of February 2018 the long awaited Falcon Heavy soared up into the sky. Watching the livestream, there was something slightly different. Instead of the usual single commentator, they had four. Behind them, hundreds of SpaceX employees cheering all the way through the launch, with bigger cheers at each milestone. It was definitely long anticipated, and I even felt the impact at university. Students were going round making sure people knew that tonight was the night that the Falcon Heavy was launching. The stream didn’t disappoint space lovers, and I highly recommend watching it on the SpaceX Youtube page.

So what actually happened,  why was this flight so important? The demo mission was the  first firing of the full Falcon Heavy configuration. Although all the rockets had been previously fired and tested at SpaceX’s rocket test facility in McGregor, TX. Consisting of “Block 2” variant side boosters (B1023.2 and B1025.2) and a “Block 3” variant core stage (B1033.1). Both the boosters had been flown before and refurbished in Hawthorne, CA. B1023.2 was flown May 27th, 2016 for Thaicom 8 launch, landing on SpaceX’s autonomous drone ship “Of Course I Still Love You”. B1025.2 flew on July 18th, 2016 for the CRS-9 mission, landing at Landing Zone (now landing zone 1). It is noted that future Falcon Heavies will likely use the “Block 5” variant. Elon Musk Claims that the development of the Falcon Heavy project has cost $500 million to get to this stage.

Falcon Heavy Before Launch
The Falcon Heavy the night before launch. From @SpaceX on Twitter

At 20:45 UTC, the Falcon Heavy lifted off of pad 39A at Kennedy Space Centre. It weighed roughly 1,400 tonnes and was 70m tall. with 2,128 pounds of thrust, the triple barreled rocket lifted off the pad with its 27 Merlin 1D engines (9 on each booster). At the time of writing it is the largest and most powerful operational rocket in use today by a factor of 2. Elon Musk gave the launch a 50-50 chance of success, but it continued through almost all of the milestones. Through Max-Q, release of boosters, and release of the main engine. The second stage performed 3 burns during the 6 hour mission to accelerate the cargo to into a heliocentric orbit. The orbit ranges from earth orbit to beyond mars (0.99 x 1.71AU). The concept of this burn was to demonstrate long coasts between the second and third burns. This ability is needed for some DoD EELV Heavy class missions, a market that SpaceX wants to compete in.

Falcon Heavy Launching
Falcon Heavy launching from pad 39A at Cape Canaveral Air Force Base.
Intended Orbit
Intended orbit of the Falcon Heavy payload, heliocentric. From Elon Musk’s Twitter.

Usually on these types of initial flights they put some sort of simulated weight in the fairing (the bit that holds the payload on top) usually a block of concrete. Elon Musk being Elon saw this as a marketing opportunity, and instead used his personal 2008 cherry red Roadster, weighing in at 1,250kg. In the driver’s seat sat a full scale human mannequin named “Starman”, wearing a SpaceX branded pressure spacesuit. The person who timed the release of the fairing showing the Tesla against the backdrop of the earth, to the music of “Life of Mars” by David Bowie, deserves a medal. Although perfectly timed, it is sometimes incorrectly attributed as “Starman” by Bowie, which would make more sense when you think about it. On the dashboard of the car is the immortal words of “don’t panic”, a tribute to A Hitchhiker’s Guide to the Galaxy, that was a clever addition. There is a livestream of the first 5 hours of Starmans trip, at which time it probably lost signal, or ran out of battery. There has been mixed reviews of this stunt. Some call it art, whereas others call it “space littering”. Some commentators such as Burnie Burns on the Roosterteeth Podcast simply don’t like the use of space for marketing purposes. Scientists at Purdue University called it “the dirtiest man-made object ever to be sent to space” due to its use driving in Los Angeles.

Tesla Roadster in Orbit
Elon Musk’s Tesla Roadster with Starman sat in the driver’s seat.

For me personally the most impressive part of the entire video was near to the end. SpaceX have had some famous problems with the landing of their reusable rockets, but during this mission they planned to land all three. The best shot of the entire livestream was the two boosters coming down at the same time, with the Cape in shot. Both boosters opening their landing legs, and coming down to land on Landing Zone 1 and 2. It was a truly epic sight, and from an engineers point of view, very impressive. The second pad was installed for these Falcon Heavy missions, and the boosters worked just as planned. The core was a slightly different story. It attempted to land on the autonomous drone ship “Of Course I Still Love You”. It completed its boost-back and reentry burn, but for the three-engine landing burn, two engines failed to ignite. The core ended up in the Atlantic. Smoothly brushed over, this was not mentioned on the Livestream, and not until a few hours later on Twitter. Even so, the things that did land correctly were impressive.

FH Side Booster Landing
The impressive shot of the side boosters landing simultaneously on LZ1 and LZ2, at Cape Canaveral.

There has been a huge amount of excitement and skepticism about the Falcon Heavy. Some have heralded it the way Elon Musk wants to get to Mars, others just love the idea that the car will be out there for “billions of years”. Although very impressive, the Falcon heavy is really designed to be a beefier version of the Falcon 9, and will probably do the same job. SpaceX are aiming in the coming years to get more contracts from the Department of Defence, and aim to get more up into space at the same time. The Falcon Heavy is all about making it cheaper for big payloads to get to space. Although it has the capability to get to Mars, and carry people, Musk has said that there are bigger plans in the pipeline for those jobs. As for the car, according to chemist William Carroll, solar and cosmic radiation will break down most of the car within a year, leaving just the aluminium frame and maybe some glass that isn’t shattered by meteorites.

The Falcon Heavy Launching
The Falcon Heavy launching, taken from behind a SpaceX hangar near the launch site.

This is a big moment for SpaceX, and the space community, and shows that there are big things coming in the sector. There are big launches aimed from the big companies this year, and new rockets being unveiled in the near future. SpaceX may have just started a new space race. For all the excessive marketing that Elon Musk does, SpaceX have definitely got their marketing message right.

To find similar photos, and to buy reasonably priced prints of some of the above visit www.marcuscotephotography.com

The Foundry: Blowing Smoke

In the last post, we saw a fire actually burning in the foundry. The concrete has set, and doesn’t fall apart while being used. After researching other designs, and using some logic, we figured we need to force more air into the system. As we designed previously, there is a large 30mm hole on the side of the forge to allow air into the fire. Unfortunately, this doesn’t seem to provide the amount of air we need to get the desired heat. We have tried a number of ways to force air into the hole, with varying success. First we literally blew into it, like you would a campfire, and it works well, but soon you start to really hyperventilate, and it’s not good. The next idea was to take a chopping board (but any board will do) and flapped it, forcing air towards the hole. This worked much better than simply blowing. Lots of air fuels the fire, and it burns really hot. The big downside is that it wastes most of the air produced, and creates some interesting smoke patterns that seem to be inefficient. Either way, it is a good cheap way to improve the forge performance.

First Tests
The foundry during its first fire, not particularly hot.

The method we eventually used to force air into the system was in the form of a fan. Before I start this section, it comes with a warning, you need to wear goggles if you try this, as will be explained. You have been warned. The initial fan was in the form of an old hairdryer, bought from a charity shop for £3. Putting it right up to the hole forced hot air directly into the hole, with very little waste air escaping. It worked very well, and the fire started to burn much hotter. It also meant we could control the amount of airflow by using the switches on the hairdryer, or simply moving it further away.

Forcing air into the forge
Forcing air into the forge using a hairdryer, the fire is visibly hotter.

Two issues came up while using this method of airflow. The first big problem is the mass of air being forced into the hole needs to go somewhere. The only place it can go is straight up, and as we don’t have a lid it just fires ash into the air. This is dangerous if gloves and goggles aren’t being worn. This ash can be hot and can take some of that fuel and heat away from the forge. A lid will fix this, and that will be covered in the next post. For this test we kept it at a low fan speed, and found a nice point where we weren’t firing ash into the air, but still giving lots of air to the fire. The second problem was that the hairdryer started getting really hot, and the plastic began to melt. Essentially this means it was too close to the fire, but if you move the fan away then the air just misses. To fix this we found a 30mm diameter iron pipe, and attached the hairdryer to it. This allowed the air to be funneled in with the fan unit being further away from the forge.

The fire burning
The fire burning with a steel tin on top to stop the ash flying out.

So what have we learnt from this fire? We need a lid. This will be a topic of further posts, but for now we know we can produce a hot fire, and the air going into the fire can be controlled. Thanks for reading, and hope to come with another update soon.

Halfpenny Bridge: The Bridge Over Nothing

If you walk down Union street in Plymouth, just before you come to Devonport you will come across what looks like a bridge. Called Stonehouse Bridge, it comes from a time when Plymouth had a very large river/lake separating Devonport and Plymouth-Town. Originally to get across the creek to what was then known as Plymouth-Dock, you had to take the pedestrian ferry, or go all the way up to Mill bridge. So in 1767 Lord Mount Edgcumbe, who was lord of the manor of East Stonehouse, and Sir John Saint Aubyn, Lord of the Manor of Stoke Damerel, obtained an act of Parliament authorising construction of a bridge. The idea was to allow for a more direct link between Plymouth-Dock and East Stonehouse. It made sense when in the Act they described the old ferry as ‘narrow and could only be used by foot passengers’.

Stonehouse Bridge, Plymouth, engraved by W.B. Cooke 1836 Clarkson Frederick Stanfield 1793-1867

The man who designed the Eddystone Lighthouse, that now stands on Plymouth Hoe, John Smeaton, was invited to design the bridge. The bridge charged a toll to get across it, like many bridges of the time, and it was fixed by the act of parliament. It cost 2d return for a 1-horse drawn vehicle, 3d for  a 2 horse vehicle, and 6d for wagons drawn by more than 2 horses. The nickname ‘Halfpenny Bridge’ was from the halfpenny it cost for pedestrians to cross, also it was sometimes pronounced ‘Ha’penny Bridge’. Interestingly it absolved the owners from paying any public or parochial rate or tax.

The old 5 horse car at the halfpenny gate

Opened in 1773, the approach to it was via Stonehouse lane (now known as King Street) and the High Street, rather than Union Street. in 1775 the first carriages began to be hired between Plymouth and Plymouth Dock, over the new bridge. Carriages were popular but Stonehouse lane was described as ‘ruinous’ and a new road was needed. A further Act of Parliament was obtained in 1784 to create the Stonehouse Turnpike Trust. In 1815  Union Street was finally opened, as a turnpike, the users paid a toll to use the bridge, that went to the upkeep of it.  So users now had to pay for the bridge and the road leading up to it. Turnpikes were very popular in the 18th and 19th century and are basically a toll road. In 1828 the bridge was raised while Devonport hill was lowered. This meant that hackney carriages could now be used to provide a route between Plymouth and Devonport the following year.

Stonehouse Bridge from Richmond Walk.

Both Plymouth and Devonport tried many times to purchase the gate, but the bridge, along with Stonehouse Mill bridge were sold in February 1890 to the General Tolls Company Ltd for £122,000. The company (with the Earl of Mount Edgcumbe and Lord Saint Levan had shares in) was registered on February 12th 1980. The idea was for the owners to collect the tolls rather than auction them, which was more common at the time. From October of 1917, servicemen and nurses could get across the bridge for free.

Stonehouse creek before being filled in, from the bridge

After long negotiations, an Act of Parliament in 1923 allowed Plymouth Town Council to buy the toll rights for £100,000. This meant that the Council could have charged tolls and collected than money for up to ten year. Instead, on April 1st 1924, the Mayor, Mr Solomon Stephens, and council visited all the toll houses and declared them free.

Stonehouse Bridge Freeing Ceremony, 1924 looking towards Devonport. From a postcard

The upper end of the creek, near the Pennycomequick, was known towards the end of the 19th century as Deadlake. St Barnabas Terrace, a road now adjacent to the park, was marked on 19th century maps of the area as Deadlake Lane. Toward the end of the 19th century, culverts were made to channel the streams that ran into deadlake, and the swampland was filled in with rubble from the quarries at Oreston and Cattedown. To celebrate queen Victoria’s reign, Victoria Park, along with the park-keeper’s lodge, was formally opened to the public in 1903.

Looking down the filled in fields, towards Stonehouse

Between Mill Bridge and Stonehouse Bridge, the creek was filled in in 1972, when 600,000 tons of ballast and rubble were used to create 19 acres of land. Now a set of pitches for Devonport High School for Boys (previously the royal naval hospital) and the pitch for Devonport RFC. When you walk along it you can see some areas, especially close to the bridge where all the rubble has been added. On the water side of the bridge you can see where the arches have been filled up. Stonehouse bridge is now more of a dam, but one with some important history for Plymouth.

Halfpenny Bridge, on the side of the creek

Four Bit Carry Adder/Subtractor Circuit

After creating my 1 bit full adder design found in a previous post, I decided to go for something a little more complicated. I wanted to prove to myself that the ripple carry system worked, so the obvious choice is to make a multi bit device. 4 bits seemed like a good amount, it’s a value used in some early ALU’s so it can be used in a future project. To make it more interesting I added in the ability to make the device a Subtractor at the same time. When you look at the schematic, it only requires one more device per adder, so it’s not even an expensive thing to implement, but adds lots of functionality. As with the 1 bit adder, I have attempted to build this adder using only single logic chips.

4 bit adder-subtractor circuit

The first stage is to know the logic circuit, its widely known and can be found pretty easily all over the web. I’m not going to explain how it’s created (I can always make a separate post on that) but I can describe how to use it. The aim is for the device to take two 4 bit inputs (0 – 15), along with a carry from another adder. So the adder needs to be able to output a value between 0 and 31. In binary this can be shown as 5 bits, so we have 2 outputs. This the S output is a 4 bit bus, and the Co output bumps this up to the 5 bits we need to make 31. A truth table can be made for this but it would be 32 lines long, so too much for this post. You could regard it as a personal challenge if you want to attempt it on your own.

So I got onto Altium and made a schematic of this circuit using some of the low voltage 7400 LVC series individual logic gates that I used on the previous adder I made. They come in SOT23-5 packages which are leaded a nice size to solder. Plus they are a size where it’s possible to probe the pins fairly easily. Luckily Altium shows the components as their logic symbols. Below I have shown the first two adders, the third and fourth are basically the same as the second one, which is the idea of the ripple carry adder.

The first two adders of the four found on the board

I also added a few LEDs to show what parts are on and off. This means the user can see the inputs and outputs. These LEDs run off the 5V input voltage, and have 220Ω current limiting resistors in series with them. Also, I have put in some 0.1 inch header pins so it can be attached into a breadboard and maybe even a micro.

The LEDs for the carry bits and outputs
The LEDs for the input bits

As a base of my circuit, I have decided on a double sided 100mm x 100mm board. This is quite big as you can see for the circuit I have made, but gives plenty of space for a soldering iron to get access. As well as this, it gives a nice amount of space for multimeter probes. I also tried to keep the individual logic chips in a similar arrangement as the schematic. This is meant to be used as a learning device, so it’s useful for the chips to line up with the diagram. The header pins for the inputs and outputs are placed on opposite sides of the board to make it more obvious for the user to see it. And the pins have designators written on the board so the user can see what each pin does. The input and output busses are placed in fairly logical places, and grouped together. There is no point having all the A inputs intertwined with the B inputs. The pins for the power and ground are on opposite sides with their own headers, only one needs to be connected for it to work. The LEDs that are directly attached to the pins are placed closer to the logic circuitry, but labeled clearly on the silkscreen. Most of the routing to the LEDs is on the underside of the board, else the top could get confusing. All the designators for components have been made half the normal size due to the small amount of parts used in the project. The below images show the PCB layout I created with the top copper being red, bottom copper being blue, and the silkscreen shown in yellow.

Top Copper

As you might be able to see, I have tried to keep all the power on the bottom side of the board. This leaves lots of space for the logic signals on the top, where the user is more likely to see. As you can see, most of the inputs and outputs of the circuit are also on the bottom side. This is because the way the busses work and input into the adder needs lots of crossing over and would add confusion into the design. This is why labels were used instead.

Bottom Copper

To make it easier to see, I made a larger image of the first and last adder in the series. As you can see, the only real difference in them is that the first has the add/subtract input shown by an LED, whereas the last shows the carry from the previous adder (C0). This is because the A/D bit is attached to all the adders, but the first bit doesn’t have a carry bit input. The carry on that adder is the input for the A/S. It serves the function of inverting the first bit, so that it works like 2’s complement when in subtract mode.

The layout of the first adder in the series
The layout of the last adder in the series

As noted above I used 7400 LVC series logic gates. The SOT23-5 package chips have the suffix of “BVD”. See the datasheets for each of the devices for more information. I have written a simple bill of materials below:

12x SN74LVC1G86DBVT – XOR gate
8x SN74LVC1G08DBVT – AND gate
4x SN74LVC1G32DBVT – OR gate
17x DO-214 LED’s
17x 0805 220Ω resistors
6x 5-pin 0.1″ header pins

The main downside to this type of adder is that is is very slow. Especially when you get to high bit amounts that you are trying to add. This adder will take at least 4 times as long as a single adder to add the two numbers together because the signal has to propage through 4 full adders. This problem is known as propagation delay, each logic chip will take a very short time to compute the output. Although this time is not perceivable by the human eye, if there are 100’s of logic gates in a row, then the delays start to add up and be a problem. If this circuit is to be used in a computer, it could need to make calculations thousands, or maybe millions of times a second, and a carry bit adder is not generally good at that. There are other, faster adders that I will show in a future post.

Why James Webb Was so Important

NASA Administrator James E. Webb
NASA Administrator James E. Webb. This was his official NASA photograph

There are not many people who know off the top of their head who James Webb is, even many lovers of space may not know who he was. Yet they are about to launch the James Webb Space Telescope into space to replace Hubble. James Webb wasn’t an engineer, or a physicist, or even really an academic; he was a lawyer and politician. He turned a small government research department into an organisation that had links to almost every state, and had control of 5% of the US federal budget. Webb’s NASA controlled the jobs of half a million workers across America, and he introduced new working practices and management techniques that are still used today.

If you were to go out and read the biographies of the astronauts, or histories of spaceflight, Webb doesn’t really come up. He was portrayed as just a bureaucrat in Washington, funnelling orders down the chain, living the politician life. In this new age of spaceflight, we see the Apollo years as some sort of poetic story, with NASA being the figurehead of the battle to win space against the evil russians. In 1961 though, America did not follow this narrative, nobody in America cared about space, least of all the brand new president, John F Kennedy. When he set up his first reshuffle of the cabinet they simply could not get anyone to run NASA, they asked 18 high level politicians, and everybody said no, space was a dead end job, and NASA was just a collection of squabbling mission centres. Eventually, JFK’s vice president, Lyndon B. Johnson suggested Jim Webb, a guy who had worked under the Roosevelt administration and had some experience with private businesses. When asked, by JFK personally, Webb agreed to run NASA, as long it was the way he wanted it. JFK, desperate for an administrator gladly agreed.

shaking hands with JFK
President Kennedy shakes hands with NASA Administrator James Webb

There had been heavy opposition to the idea of manned spaceflight. Up to this point, the head of the President’s Science Advisory Committee, Jerome Wiesner, had issued a critical report on project mercury. Kennedy, as a senator he had openly opposed the space program and wanted to terminate it. Kennedy put his vice president LBJ as the head of the National Aeronautics and Space Council because he had helped create NASA, but it was mainly to get him out of the way. Although Kennedy did try and reach out for international cooperation in space in his state of the union address in January 1961, he got nothing from Khrushchev. Kennedy was poised to dismantle the effort for space, purely because of the massive expense.

The space Council
Vice President Lyndon B. Johnson (seated, center) presides over a meeting of the National Aeronautics and Space Council.

He began his NASA administration on February 14th 1961. A month later on April 12th, Yuri Gagarin became the first man to orbit the earth. Reinforcing some fears that America was being left behind in a technological competition with the Soviet Union, America suddenly cared about space. Kennedy made a U-turn and space sped to the top of the list.  This lead to Kennedy making his famous speech on May 21st where he spoke those famous words “we will put a man on the moon before the decade is out”. Kennedy wanted to take lead in the space race. Suddenly, putting a man on the moon was the number one priority.

Kennedy Talking to Congress
MAy 1961, Kennedy proposes landing a man on the moon to congress. LBJ and Sam Rayburn sit behind him.

This meant that James Webb just got handed the opportunity to run the biggest single project the country had ever seen. Webb was told to go back to his engineers and figure out how much it will cost to get to the moon. His engineers came up with the number of $10 billion (a scary big number in the 1960’s), and sheepishly told Webb, expecting to be told to make cuts and slashes to the plan. Instead he told them to go higher, because he knew problems would come their way, and extra money will need to be spent, so they come back with the figure of $13 billion. Webb accepts the number, and goes to congress and tells them he needs $20 billion over the next 7 years. Jaws hit the floor, but he used this political knowledge to get a huge amount of leverage.

The key leverage he had was jobs, and he knew it. At its height, NASA employed half a million people in some form, that’s roughly the number of people living in Wyoming. The two biggest investments were in Cape Canaveral, FL and Houston, TX. The most controversial was the Manned Spaceflight Centre in Houston, donated by Rice University. Originally based in Langley Virginia, and named the Space Task Group, the senator didn’t care much for space. The entire operation was moved to Houston, LBJ’s home state. It was central, and had good universities surrounding it. There were many Texas based representatives in the space political landscapes at that time, such as Sam Rayburn, the speaker of the House of Representatives.

Johnson Space Centre
Manned Spaceflight Centre, Texas, one of the biggest employers in Texas for a long time. with over 3000 federal workers, and 100 buildings

One thing that Webb understood was what NASA needed to run. He implemented a very flat organisational structure, with very few middle managers. Webb was the very top, controlling Washington. He also had the head of NACA (precursor to NASA) Hugh L. Dryden as an associate director. He had overseen the development of the x-15, and understood the technical needs of Apollo. Also Robert Seamans, also an associate director, acted as the general manager of NASA, and oversaw the everyday running of the program. Using a team of people, each with their own particular strengths helped NASA, especially in the early growth years, much more so than any one of them could achieve on their own.

Webb in a Gemini Trainer
Webb in a Gemini Trainer

Part of what James Webb did, to the dislike of congress, was to invest in academia, specifically universities. $30 million dollars a year was put into the Universities Development Fund. A fund designed to help students get into engineering, and to develop talent, skills, and academics that could not only work for NASA, but help the science behind it. As it was taken from a fund that congress had no control over, the money continued to help 7000-8000 students a year get through university at a time where NASA needed engineers. Webb believed that NASA was more than just the one shot to the moon, and frequently fought with the presidents on that fact. He wanted NASA, and space exploration to benefit science, engineering and even society. He believed that this project could fix other problems not even related to space, such as poverty and disease. The management style of NASA, and the way these big projects were handled showed the impossible could be achieved. He frequently lectured on this subject, and universities became an important part of NASA.

Launch_Complex_34_Tour
Webb, Vice President Lyndon Johnson, Kurt Debus, and President John F. Kennedy receive a briefing on Saturn I launch operations

There was huge pressure from washington to spend all of NASA’s budget purely on the Apollo moonshot. Webb was instrumental in making sure that NASA and spaceflight was more than that. be made sure other projects like the Mariner and Pioneer space programs happened, and that JPL still functioned even with a terrible track record at the time. At the time, the academic community worked with NASA, in large part because of the importance Webb put on furthering science. Webb would frequently lecture at universities, and teach about the management styles that made NASA was. Unfortunately, some in Washington didn’t care for the extra spending, especially the states that did not have a mission centre or any of the major manufacturing plants located there. So when the Apollo 1 fire happened, there were a small group that were willing to use it as a way to make changes.

Closeup of James E. Webb, National Aeronautics and space administration

The Apollo 1 fire was a very unfortunate accident, and a national tragedy. For some, it highlighted some major problems with the Apollo program and how it had been run by the major contractor North American Aviation. Committees were set up, and Webb suddenly went from running NASA to trying to defend it. During the inquests, NASA still ran, it continued to fix problems and aim for the moon. This was because James Webb was there defending it. Left to just take the heat, some believe (me included) NASA’s funding would have been significantly cut, and we may have never got to the moon. Webb stood up in Washington and fought hard for the continuation of the project, defending the decisions that his team had made. At the end of it, he had used up most of his political sway, and called in so many favours that NASA was safe for the time being, and that Apollo was possible.

Webb presents NASA’s Group Achievement Award to Kennedy Space Center Director Kurt H. Debus, while Wernher von Braun (center) looks on

At this point, Johnson had decided not to run for re-election, Webb felt that he should step down to allow Nixon to choose his own administrator. On October 7, 1968 he stepped down from office. To put that into perspective, Apollo 11 landed on the moon July 20th, 1969, barely a year later. Webb went on to be a part of many advisory boards and served as regent for the Smithsonian institute. He died in 1992, and was buried in Arlington National cemetery.

This post was inspired by reading the book: The Man Who Ran The Moon by Piers Bizony. For anyone interested in the subject of how Webb actually made his dealings, and a much more detailed account of how NASA became what it is, I recommend this book. He also did a Lecture on Webb that I found on YouTube where he tells the story really well.

 

The Foundry: The First Fire

Now it’s time to test the foundry, or at least the first version of it. This also has a benefit to it. Some others who have made this style of foundry have found this process helps the concrete to fully cure, and dry any leftover water still in the mixture. This process is pretty simple, most suggest using charcoal as the main fuel. We went down the local hardware store and they had a sale on charcoal briquettes. These are small and there are plenty of them, and fit nicely in the foundry. Light the fire in any way you are used to, we used fire lighters and some cheap kindling, also from the hardware store. If you don’t know how to light fires safely, find somebody who does.

First Tests
The foundry having its first fire, drying it out and seeing whether it can survive.

We didn’t use much to start with, this is meant to be a calm fire to help cure the concrete, and test it can deal with at least some hot temperatures. It was also to see how well it burnt with the air hole we put in. Main problems we found were that the air hole did not provide enough oxygen into the system, so the fire was slightly stinted. We tried blowing into the hole a few times, and the fire definitely got bigger, but it also sprayed ash into the air, so be very careful of that. We also noticed something most blogs talk about, lots of heat escapes from the top. With the foundry having such a big opening, very little of the heat is retained, and the fire has to work harder to keep the heat at a set level. A lid is often the best way to battle this.

The aftermath
The foundry after its first test and the ash was scraped out of it.

So what have we learnt from our first fire? We need a lid, and some way to force air into the hole. This will be a topic of further posts, but for now we know our concrete foundry can withstand the heat of a fire, and is now a little bit darker from all the ash. Thanks for reading, and hope to come with another update soon.

One Bit Adder Project

One thing that has always been interesting to me is using logic circuitry in electronics. It’s easy to implement something on a microcontroller in just a few lines of code, but the real challenge comes from making a boolean project using real logic gates. It’s something we all learn about if you have taken a basic computer science class, or even digital electronics. One of the first circuits you ever learn about is the adder. It’s pretty simple, teaches you how to cancel down boolean equations, and only has a few inputs and outputs. I have decided to try and make the circuit using real components, and see if I can get it to work.

full adder layout

The first stage is to know the logic circuit, its widely known and can be found pretty easily all over the web. I’m not going to explain how it’s created (I can always make a separate post on that) but I can describe how to use it. The aim is for the device to take two 1 bit inputs, along with a carry from another adder. So the adder needs to be able to output a value between 0 and 3. In binary this can be shown as 2 bits, so we have 2 outputs. The S output represents bit 1, and the Co output represents bit 2. Below is the truth table I used, if you want a little challenge, try and get the above circuit using boolean algebra.

A B Ci Co S
0 0 0 0 0
0 0 1 0 1
0 1 0 0 1
0 1 1 1 0
1 0 0 0 1
1 0 1 1 0
1 1 0 1 0
1 1 1 1 1

So I got onto Altium and made a schematic of this circuit using some of the low voltage 7400 LVC series individual logic gates. They come in SOT23-5 packages which are leaded and a nice size to solder. Plus they are a size where it’s possible to probe the pins fairly easily. Luckily Altium shows the components as their logic symbols.

1 bit adder 1 schematic

I also added a few LEDs to show what parts are on and off. This means the user can see the inputs and outputs. These LEDs run off the 5V input voltage, and have 220Ω current limiting resistors in series with them. Also, I have put in some 0.1 inch header pins so it can be attached into a breadboard and maybe even a micro.

1 bit adder 1 schematic

As a base of my circuit, I have decided on a double sided 50mm x 50mm board. This is quite big as you can see for the circuit I have made, but gives plenty of space for a soldering iron to get access. As well as this, it gives a nice amount of space for multimeter probes. I also tried to keep the individual logic chips in the same arrangement as the schematic. This is meant to be used as a learning device, so it’s useful for the chips to line up with the diagram. The header pins for the inputs and outputs are placed on opposite sides of the board to make it more obvious for the user to see it. The pins for the power and ground are on the same side on both headers. The LEDs that are directly attached to the pins are kept close to them, and the track is fairly obvious to show where the signal is from. The silkscreen labels which LED designates which input/output. All the designators have been made half the normal size due to the small amount of parts used in the project. The below images show the PCB layout I created with the top copper being red, bottom copper being blue, and the silkscreen shown in yellow.

1 bit adder 1 PCB top

As you might be able to see, I have tried to keep all the power on the bottom side of the board. This leaves lots of space for the logic signals on the top, where the user is more likely to see. As you can see, not all signals are on the top side due to circuit constraints, but signals that do swap over are generally short jump, and straight lines, This makes it more obvious where the tracks go without having to flip the board.

1 bit adder 1 PCB bottom

As noted above I used 7400 LVC series logic gates. The SOT23-5 package chips have the suffix of “BVD”. See the datasheets for each of the devices for more information. I have written a simple bill of materials below:

2x SN74LVC1G86DBVT – XOR gate
2x SN74LVC1G08DBVT – AND gate
1x SN74LVC1G32DBVT – OR gate
5x DO-214 LED’s
5x 0805 220Ω resistors
2x 5-pin 0.1″ header pins

How a Voltage Regulator Works: LM7805

Voltage regulators are one of the first electronic components you get introduced to as a hobbyist. Really useful when starting out, it simply takes a voltage that is too high, and reduces it down to a set voltage that you want, usually defined by the component. Solves the problem of having batteries or power supplies being a different voltage to the thing you are powering (such as your Arduino), and at as little as 50p from ebay they are easily acquired. Sounds like a great solution, but there is an issue, they are terribly inefficient. They are known to get very hot when used at high currents, and often need hefty heatsinks to stop the magic smoke from being released. To demonstrate why they get so hot we need to think about what happens during use. Remembering Kirchoff, the current going into a system is the same as the current going out of the system. If we use a simplified version of the regulator, the only thing this device changes is the voltage of the output. Due to the minimal current lost powering the circuit we assume the vast majority of power lost is in heat. Using the basic equation of:

Power (W) = Voltage (V) x Current (I)

So if we use an example of the LM7805 made by On Semiconductor (previously Fairchild) that can regulate 5V at 1A. It’s a pretty standard component, and is very typical of a voltage regulator.

If we use a 9V input the power going in is 9V x 1A = 9W.

The output power is 5V x 1A = 5W.

This means that there is 4W of power being dissipated from the regulator as wasted heat. This is a large amount when considering the size of the packages available. When thinking about problems excessive heat can cause in a circuit, it can quite easily damage itself and other components around it when not designed properly. It is why there are often big chunks of aluminium attached to the back of the components to act as a heat sink.

7805
7805 chip in a TO-220 package. Notice the heat sink on the rear with a screw mount.

This post isnt meant to dissuade you from using regulators, they have their place in electronic circuits, and are a great starting point. All electronic engineers need to have a broad understanding of the advantages and disadvantages of linear voltage regulators to be able to handle them properly.

How it Works

LM78xx schematic 2 coloured
Schematic of the silicon inside an LM78xx device, coloured relating to the function of each area.

The above schematic can be found on the datasheet, but it’s been coloured in to show the different sections of the circuit.

The most important component in the above schematic is Q16 (Red), it controls the current between the input and output, therefore the voltage. It is placed in a darlington pair configuration with Q15 (Orange). In this configuration Q16 is amplifying the current amplified by Q15. This means that Q15 can be used to introduce error feedback. The Blue section contains a voltage divider that scales the output voltage so that it can be used by the bandgap circuit. This bandgap circuit is found in the yellow section (Q1 and Q6). This bandgap reference produces an error signal that is fed into Q7 (orange). A bandgap is used because it can provide a stable output even when the temperature of the device changes.

The orange section takes this error and amplifies it through Q15 and the darlington configuration described earlier. The purple section has overheating protection (Q13) and excessive output current protection (Q14). Occasionally on these schematics you also find excessive input voltage protection marked as Q19 in this section. These shutdown the regulator in fault conditions like overcurrent or getting too hot. The Green section is known as the “start up” circuit, because it provides the initial current needed to power the bandgap circuitry. This gives a jumpstart to the circuit when it needs it.

I chose the LM7805 because 5V is a common value to be used, but the LM78xx series has many different preset voltage versions. The bandgap circuit is trying to get its input to 1.25V, this is from the voltage divider found in the blue section. As R20 is a variable resistor, the voltage divider can be calibrated during manufacture to output exactly 1.25V at any chosen output voltage. This is great for a manufacturer because they make lots of the same chip, and it can be made to suit any voltage output they want. This is also similar to the way some adjustable voltage regulators work, such as the LM317. In adjustable chips, the voltage divider is made by the designer externally, meaning it can be applied to any situation with a simple change of resistors.

Basic Configuration

Looking at the datasheet, there are many applications for the device. but the simplest one is just an input and an output. All that’s needed is a couple of decoupling capacitors to smooth out AC signals and random noise. Voltage regulators work best with clean, smooth power. There is also the need, due to the voltage drop across the transistors, for the input voltage to be at least 2V above the required output. This is always a good rule of thumb to go by when it comes to regulators.

LM78xx basic configuration
LM78xx basic configuration

I would recommend people read the datasheet and have a play with different voltage inputs and current outputs, see how easy it is for it to get hot. In that datasheet there are some other good applications using the device, you can turn it into an adjustable voltage output, constant current supply and high current supply. These are also good projects for learning more about transistors and op amps. Equally, there are other types and brands of regulator out there, some cheap, and some quite expensive, it is worth shopping around for  the ones that suit you.