Category: Spaceflight

The biggest Mach diamonds ever!

Together, all these engines produce 75.9 MN of thrust, much more than Saturn 5’s 34.5 MN.

The first question you might want answered as you read this title will be, ‘What on Earth is a ‘Mach diamond’?’ I’m glad you asked.

If you’re interested in rockets and spaceflight you may already know. Where there are rocket engines, there will be Mach diamonds (also known as ‘shock diamonds’). They are formed by the high velocity of the gases leaving a powerful jet or rocket engine. The shock waves created by this process interact with the ambient air around the nozzle, sculpting the exhaust into angled zones. When seen from the side, these appear as a repeated diamond pattern.

Mach diamonds from an F-16 on afterburner – Image from Wikimedia

The largest rocket ever built is SpaceX’s Super Heavy booster designed to lift Starship to a high altitude on the first part of its journey to orbital velocity. This booster is powered by 33 Raptor engines clustered closely together; they behave rather like a single engine with a 9 m diameter nozzle. When the rocket flew for the second time in 2023, giant Mach diamonds appeared, 9 m across and 6 m in length. These truly are the world’s biggest Mach diamonds ever – by a very considerable margin.

Super Heavy’s engines – SpaceX

This view shows all 33 Raptors firing shortly after liftoff on the 2nd flight test (IFT-2). Each engine bell has a diameter of 1.3 m and the rocket itself has a diameter of 9 m. Together, all these engines produce 75.9 MN of thrust, much more than Saturn 5’s 34.5 MN.

IFT-2 – BocaChicaGal

Here’s an image of the IFT-2 vehicle shortly after launch. The first Mach diamond is very sharply defined, subsequent diamonds less so as the exhaust plume slows, cools and becomes more ragged. Four can be clearly identified with some hints of a fifth and sixth.

So what is happening here? How are the diamonds generated?

Because a rocket engine is all about producing thrust, the velocity of the exhaust is paramount. Rocket engines are designed to maximise velocity and in doing so they minimise pressure. Inside the combustion chamber, pressures are extremely high; but the bell shape of a rocket nozzle expands the gases and directs them downwards. The pressure inside the exiting plume is much lower than the ambient air pressure. This pressure difference ‘squeezes’ the plume and prevents it spreading out sideways.

Higher in the atmosphere, air pressure is lower and the mach diamonds vanish; as atmospheric pressure drops away towards the vacuum of space, the exhaust plume spreads out sideways more and more because the exhaust gas is now at a higher pressure than the diminishing, surrounding air. Notice how the spacing of the diamonds decreases with distance from the rocket. This is because the exhaust velocity is falling off as the plume interacts and mixes with the air around it.

That’s the essence of the process in everyday language. Check the links below if you want more technical detail.

See also:

Blast from the past… 8

We are often in situations where we’re amongst people we recognise, but know almost nothing about.

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Notes from bygone years – Julys duly remembered
Hint: Click on the thumbnails for larger images.

A year ago

On 7th July 2022 I noted that ‘the Conservative party is in a state of confusion right now’. Not a lot has changed in the last twelve months; it seems the Conservative ship is still foundering. I included a picture of a sinking ship in my article, here it is again. I also argued for a general election as soon as possible and we’re still waiting on that one! So the big question now is, ‘Will the Conservatives still be in power in July 2024?’ Hard to say, isn’t it! In my judgement it’s very unlikely, but we’ll have to wait and see. The last possible date for the next general election is 28th February 2025. (See the original post.)

Graphic of a sinking ship

<Jun 2022 – Aug 2022>

Two years ago
Starship’s first launch, 20th April 2023 – Image from Wikimedia

In July 2021, SpaceX‘s Superheavy Booster 3 was being tested at Boca Chica in Texas. They continue to develop and build boosters (and Starships too) at a prodigious rate, and have already launched the full stack on it’s first test flight. That flight failed to reach orbit, and caused serious damage to the launch mount but, following repairs, they are very nearly ready for a second attempt and have made a lot of changes following lessons learned from flight 1.

Five years ago
The JDMC cover

In July 2018 I shared an extract from my short guide, JDMC. I emphasised the work of the Holy Spirit in church life and looked at ways we can recognise and value his activity.

I didn’t want JDMC to be only about what we do, but more significantly about what Jesus does. (Read the original article)

Ten years ago
Ambience Cafe, St Neots

Research shows we are often in situations where we’re amongst people we recognise, but know almost nothing about. In July 2013 I was thinking about this and how I might notice and engage with such people. (Read the original article)

Fifteen years ago
Still from a video about the hymn

In July 2008 I wrote about the famous Welsh hymn, ‘Dyma gariad fel y moroedd’ or in English ‘Here is love vast as the ocean’. Read about the hymn’s origins and listen to it in the original article.

Twenty years ago
Crow’s nest on HMS Warrior

July 2003 saw us meeting at home to listen to what the Spirit would say and watch what he would do. And of course, we were not disappointed. Afterwards I posted ‘Fallen and lifted up‘ to capture something of that evening.

Twenty-five years ago
Kimbolton Market Place

In July 1998 we visited Kimbolton, just a short distance from our home in Tilbrook. Although it’s a village, Kimbolton always seemed much more like a small town with a market place and Kimbolton Castle, now a private school.

Thirty years ago
The Sealed Knot

In July 1993 Judy, Debbie and Beth went to see a Sealed-Knot re-enactment of a Civil War battle. I didn’t go to this as I was probably at work at the time.

Thirty-five years ago
Mum and Mickey

In July 1988 My Mum was sixty and we had a party at The Catherine Wheel pub in Bibury. Here she is unwrapping a present – a Mickey Mouse landline telephone. She had always wanted one of these!

Forty years ago
Apple pollen tubes

In July 1983 my mathematician friend, Phil, and I had a scientific paper published. Phil built a mathematical model for the effect of temperature on apple pollen tubes. This was based on experimental measurements I’d made in spring 1982.

Forty-five years ago

In July 1978 Beth was just two months old (whoops, I think I just gave her age away). We were living in a terraced house in Yatton and I was working on plum and apple pollination.

Fifty years ago
Belland Drive in Charlton Kings

In July 1973 I inspected the base for a greenhouse with my father-in-law, Ron Hill. Here we are, having a good look. As you can see, Ron’s garden in Charlton Kings was beautifully maintained.

Fifty-five years ago

In July 1968 I celebrated my 20th birthday. I don’t remember the occasion, but it would have involved a bit of a party with my Mum and Dad, my three sisters, Judy, and possibly her parents and brother too. From my current perspective it seems a very long time ago!

Sixty years ago
A beach on the Welsh coast

In July 1963 I was 14 years old and we might have been on holiday, but more likely it would have been August. In any case, here’s my Dad taking a photo of the family on the beach on the coast of Ceredigion, Wales.

Sixty-five years ago

In July 1958 I turned ten-years-old, and I’d finished my fifth year of junior education. It was the summer holiday, hooray!

Seventy years ago

In July 1953 I was four, turning five and hadn’t yet started school. Mum, Dad, my little sister, Cindy, and I lived in Queen Anne’s Road on the Beeches estate in Cirencester.

Seventy-five years ago

July 1948 was the month I was born. I was one of the first two children to be delivered at Cirencester’s new maternity hospital. It’s now the main building of today’s Cirencester Hospital. < >

Eighty years ago

On 29th July 1943 my Dad cycled home from school at the end of term. It was his last day of full-time education. < >

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Starship launch attempt postponed

** LATEST ** – The next launch attempt is now scheduled for Thursday 20th April. Check the latest news at Spaceflight Now.

Monday’s planned test flight of the Super Heavy booster carrying Starship was called off due to a pressurisation issue caused by a failed valve. The booster’s ability to carry a significant load (like a fully fuelled Starship) depends on the fuel tanks being pressurised at all times. It’s the same process that makes drinks cans so strong despite being very thin walls. An empty can crumples whereas an unopened can is pressurised and is significantly stronger.

If the valve issue can be fixed on Tuesday, there might be a new launch attempt on Wednesday. Watch this space (no pun intended).

See also:

Starship’s first launch

Just a short post this time, to alert anyone who may not know… SpaceX is planning the first ever launch of Starship on an orbital flight tomorrow, Monday 17th April.

There are several places you can watch this attempt live on YouTube. I recommend three of them in particular. If you’re new to all this, try the SpaceX stream. If you’re more knowledgeable you might prefer one of the others.

  • Felix Schlang, a German who moved to Florida to be closer to the action
  • Marcus House, an Australian spaceflight enthusiast in Tasmania
  • SpaceX, the company’s official stream

I just wanted to get this alert out today. I’ll be back after the launch attempt with more thoughts. (More details about Super Heavy and Starship).

Blast from the past… 4

In March 1998, Donna and I were married!

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Notes from bygone years – March after March after March

Two years ago

There were no posts in March 2021, but I walked a long section of the old Thames and Severn Canal. The photo shows the towpath on the left and the bed of the canal on the right. The canal is being restored, but it will be a long time before this section can carry barges again.

The old canal and towpath
Five years ago

In March 2018 I posted about moving into our new house and adding an extension (‘Our new home in the Cotswolds‘). The building work was disruptive in the extreme, of course. We had to move out for four weeks, and make do with just part of the original space for much longer than that. But it was worth it.

The lounge in chaos
We used to watch TV here!
Ten years ago
Grasshopper landing

In March 2013 I wrote about a TED interview with Elon Musk. Perhaps you haven’t heard of the TED talks, but everybody has heard of Elon. The post is interesting: Musk was already experimentally landing rockets ten years ago, and TED continues to be a great ideas platform. Take a look and explore the links in the original post.

Fifteen years ago

I reported on a meeting at home in March 2008.

Rachael also shared a picture of an old-fashioned plough making furrows. The soil needs to be churned up and overturned before something new can be grown. There is a necessary process of breaking before the land can be used.

We thought about how Father releases us from ourselves. At the beginning he said, ‘Let there be light’; he still speaks those words into his people today and pours light into the darkest places in our hearts.

Twenty years ago

March 2003, another early blog post about a meeting at home. This time there were only two of us, but we heard such a lot! For example, that the tiny stonecrop, the great cedar, and the mighty oak tree were all planted by Father’s hand. The important thing is not to be big or strong, but to be planted by the master.

Twenty-five years ago

And in March 1998, Donna and I were married!

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SpaceX’s Starship launch

For this first flight both parts of the vehicle will be lost after landing on the sea (but hopefully not before)

Elon Musk’s company, SpaceX, is close to the first launch of their new spacecraft – Starship. This is an exciting step forward in space flight technology as fully reusable Starship versions are planned to return NASA astronauts to the moon, act as orbital fuel tankers, take people and materials to destinations throughout the solar system, and colonise Mars.

The world’s most powerful rocket is likely to make its first orbital flight attempt during March. Whatever happens, the attempt will be spectacular in the extreme! With twice the thrust of NASA’s SLS rocket, SpaceX’s Super Heavy booster will attempt a launch from Starbase on the Texas coast, heading east. The Starship will separate and pass between Florida and Cuba.

Starship on the pad – Image from Wikimedia

The Super Heavy booster will attempt a landing on the surface of the sea, offshore of its launch point. When fully operational, SpaceX intends that Super Heavy boosters will return to the launch site to be caught in mid-air by arms on the launch tower. Starship will attempt a landing, also on the sea surface, north of Hawaii, but again, the intention is to eventually catch Starship at the launch site as well.

For this first flight both parts of the vehicle will be lost after landing on the sea (but hopefully not before). It’s likely they will attempt to hover above the sea surface to practice the manoeuvre they will need to perform for a catch. Once landing precision is good enough, SpaceX will attempt the first catches. But that’s something for future flights and will depend on data returned from this first attempt. You can’t put a note in your diary to watch the launch as we don’t yet know exactly when it will happen. But I’ll keep you posted here on JHM.

The previous step forward for Starship was a static fire by the Super Heavy booster on 9th February. This is worth watching in this video clip from NASA. Thirty-one of the booster’s thirty-three engines fired for the duration of the test, one was not ignited at all, and one shut down early. The engines fired at half thrust during the test, but for the first launch they’ll be run at 90% thrust.

See also:

The SpaceX website carries an introduction to the concept of the Starship system.

The launch is listed on Spaceflight Now’s Launch Schedule page and on Next Spaceflight’s SpaceX Launch Manifest page. You can check those sources for schedule updates as they become available.

Wikipedia has a good article about the Starship vehicle covering details of size, thrust, the development process, purpose, capabilities and so on.

For YouTube channels tracking Starship developments I highly recommend Everyday Astronaut, Marcus House, and What about it!?

Falcon 1

Things have come a very long way in less than 12 years!

Here’s a bit of history for you – SpaceX’s Crew Dragon vehicle is currently docked to the International Space Station (ISS) having safely delivered two NASA astronauts, bringing the number of crew on the ISS to five. The rocket used to put Crew Dragon into orbit was SpaceX’s workhorse – Falcon 9.

But you already knew that, right?

Well, on 29th September 2008 I posted an item about SpaceX’s first successful launch to orbit using their Falcon 1. Things have come a very long way in less than 12 years!

In the next few days I’ll try to write a piece about SpaceX’s Crew Dragon flight – watch this space (pun not intended).