The Insane Engineering of Re-Entry

Summary

This script delves into the intricate engineering behind the Space Shuttle's re-entry process, highlighting its unique challenges and solutions. From the precise OMS engine burn to the heat-resistant materials and ingenious design, it details how the Shuttle withstood extreme temperatures and atmospheric conditions. The summary also touches on the Shuttle's aerodynamic flight capabilities and the meticulous landing procedures, showcasing the remarkable feats of aerospace engineering that made space travel and re-entry possible.

Takeaways

• 🚀 The Space Shuttle was a unique spacecraft designed to survive the intense heat of re-entry and transition to aerodynamic flight, requiring a balance between the design of an unpowered glider and a re-entry vehicle.
• 🔥 During re-entry, the Shuttle experienced temperatures up to 1650 degrees Celsius, necessitating specialized materials and engineering solutions to protect the aluminum airframe.
• 🛠 The Shuttle's re-entry began with a precise burn of the orbital maneuvering system engines to adjust its velocity and trajectory for atmospheric re-entry.
• 🌌 To manage the extreme heat, the Shuttle used a combination of a blunt body design for heat dispersion, specialized heat-resistant materials like reinforced carbon-carbon composites for the leading edges, and thermal protection tiles for the underside.
• 🛬 The Shuttle's design was influenced by the X-15, the fastest plane in history, which provided insights into hypersonic flight but also highlighted the limitations of certain materials and approaches for the Shuttle's re-entry system.
• ✈️ The Shuttle's wings and tail were carefully molded to generate lift and control during re-entry and transition to gliding flight, with a focus on the entry flight corridor for a safe descent.
• 🔄 The Shuttle faced a communication blackout during the peak of re-entry due to the plasma layer formed around it, which interfered with electromagnetic signals.
• 🛤️ The Shuttle's final approach and landing required careful management of its energy and trajectory, with the use of specialized training aircraft to prepare pilots for the unique challenges of landing a glider with no powered flight capabilities.
• 💺 The Shuttle's interior was protected from heat by a combination of heat shields, insulating tiles, and materials with varying temperature resistance, including silica fibers and nomex felt.
• 🔧 The Shuttle's maintenance and refurbishment between flights were simplified by the use of reusable and replaceable heat shield components, although the process remained complex and labor-intensive.
• 🖥️ The script concludes with a promotion for Onshape, a cloud-based CAD system that offers real-time collaboration and advanced design capabilities, highlighting a shift from traditional hand-drafting to modern digital design tools.

Q & A

What is the most difficult portion of the Space Shuttle Orbiter's mission?

The most difficult portion of the Space Shuttle Orbiter's mission is the re-entry, where it has to journey through the earth’s upper atmosphere at extremely high speeds, creating a layer of superheated plasma around the aircraft.

How does the Space Shuttle manage to transition from re-entry to aerodynamic flight?

The Space Shuttle manages to transition from re-entry to aerodynamic flight by carefully moulding its wings and tail, balancing the needs of an unpowered glider with the needs of a re-entry vehicle.

What is the purpose of the 2-4 minute burn of the orbital manoeuvring system engines?

The purpose of the 2-4 minute burn of the orbital manoeuvring system engines is to reduce the orbiter's speed by just 0.1 kilometre per second, lowering its orbit enough to bring it into a collision course with the earth’s upper atmosphere.

What is the entry flight corridor and why is it significant?

The entry flight corridor is a narrow window of speed and atmospheric conditions that the orbiter must navigate through during re-entry. It is significant because bleeding too little or too much speed can result in overshooting the window or catastrophic overheating.

What material was used for the Space Shuttle's airframe and why?

The Space Shuttle's airframe was made from lightweight aluminium, which has a lower maximum operating temperature than Inconel X, but is much lighter, making it suitable for an aircraft designed to be carried to orbit.

Why was the ablative coating used on the X-15 unsuitable for the Space Shuttle?

The ablative coating used on the X-15 was unsuitable for the Space Shuttle because it had a habit of burning away and attaching itself to the cockpit windows, potentially blinding the pilots, and it was not reusable, which would increase the cost of refurbishing the shuttle between flights.

How does the Space Shuttle protect its surface from the superheated plasma during re-entry?

The Space Shuttle protects its surface by keeping the superheated plasma as far away from the surface as possible through careful design of the nose, wings, and belly to ensure shockwaves are kept at bay.

What is the role of the rear body flap during re-entry?

The rear body flap serves as a massive control surface to manage the shuttle's trajectory during re-entry. It also doubles as a heat shield for the shuttle's main engines, protecting them from the heat of re-entry.

What material is used for the leading edges of the Space Shuttle's wings and why?

The leading edges of the Space Shuttle's wings are made of a reinforced carbon-carbon composite. This material is capable of withstanding temperatures up to 1510 degrees Celsius, making it ideal for the hottest parts of the shuttle.

How does the Space Shuttle manage its trajectory to target its landing area during re-entry?

The Space Shuttle manages its trajectory by banking, which splits the lift into vertical and horizontal components. This allows the shuttle to adjust its trajectory to target its landing area without lowering its angle of attack.

What are the challenges faced by the Space Shuttle during the final approach and landing?

The Space Shuttle faces challenges such as managing its energy and trajectory in the absence of powered flight, dealing with the immense drag created by its blunt body design, and ensuring a safe landing on a precise runway from a high-speed glide approach.

Outlines

00:00

🚀 Space Shuttle Re-entry Engineering

The Space Shuttle's re-entry process is explored, highlighting its unique engineering challenges. After 7 days in orbit, the Orbiter begins its perilous journey through Earth's upper atmosphere, where it encounters extreme heat and friction, necessitating a specialized design. The Shuttle's ability to transition from a re-entry vehicle to an aerodynamic glider is underscored, with emphasis on the careful shaping of its wings and tail. The video details the critical OMS engine burn to adjust the orbiter's speed and trajectory for re-entry, and the importance of the entry flight corridor to avoid overheating or missing the atmosphere. The Shuttle's design, influenced by the X-15, had to overcome issues with ablative coatings and the limitations of using lightweight aluminum instead of heat-resistant Inconel X, is also discussed.

05:02

🔥 Thermal Protection Systems of the Space Shuttle

This paragraph delves into the thermal protection challenges faced during the Space Shuttle's re-entry. The nose and wings, being the primary heat shields, had to withstand temperatures up to 1650 degrees Celsius. The use of a blunt body design to create a bow shock wave and insulating air layer is explained, as is the Columbia shuttle disaster resulting from damage to the wing's leading edge. The development of the reinforced carbon-carbon composite for the leading edges is highlighted, along with the need for a non-conductive material to attach these heat shields to the aluminum frame. The use of insulating tiles, both low and high-temperature varieties, and their specific coatings for heat reflection or dissipation, is also covered, emphasizing the meticulous assembly and placement of these tiles for optimal protection.

10:08

🛠 Space Shuttle's Heat Shield and Structural Flexibility

The paragraph discusses the Space Shuttle's heat shield and the need for structural flexibility to accommodate thermal expansion during re-entry. The use of flexible nomex felt beneath the heat-resistant tiles is explained to prevent damage from the airframe's expansion. The importance of using a high-temperature adhesive to attach the tiles and the inclusion of expansion gaps to avoid breakage are highlighted. The paragraph also covers the use of flexible heat shields made from silica and nomex fibers for areas of lower temperatures and the unique control challenges of maintaining a 40-degree angle of attack at hypersonic speeds, including the role of the rear body flap as both a control surface and a heat shield for the main engines.

15:08

✈️ Space Shuttle's Aerodynamics and Landing Procedure

This section examines the Space Shuttle's unique aerodynamics and the complexities of its landing procedure. The need for large delta wings to achieve the crossrange capability is discussed, along with the Air Force's requirement for the shuttle to return to the launch site after a single orbit. The challenges of managing the shuttle's energy and trajectory for a precise landing are highlighted, including the use of banking to adjust lift and the peculiar control behavior at hypersonic speeds. The paragraph also describes the Shuttle's steep glide approach path and the use of speed brakes and rudder deployment for deceleration and landing, as well as the intensive training required for pilots to manage this unique aircraft.

20:11

🛫 The Space Shuttle Program and its Legacy

The final paragraph reflects on the Space Shuttle program, from its engineering marvels to its operational procedures. It discusses the program's inception, the unique design requirements, and the intensive training for pilots. The paragraph also touches on the contingency planning for potential abort scenarios and the support infrastructure at various landing sites worldwide. The narrative concludes with the shuttle's post-mission procedures, including the refurbishment process and the transportation of the orbiter back to Florida. The video script concludes with a nod to the evolution of design tools, highlighting the modern capabilities of computer-aided design and the advantages of cloud-based systems like Onshape.

25:16

🖥️ The Advantages of Cloud-based CAD with Onshape

The concluding part of the script promotes Onshape, a cloud-based CAD system, emphasizing its benefits for engineers and designers. Onshape's capacity for real-time collaboration, the elimination of version control issues, and its accessibility across various devices and operating systems are highlighted. The paragraph also underscores the system's ability to perform compute-intensive tasks like Finite Element Analysis and rendering in the cloud, thereby streamlining the design process. A special offer for the Onshape Professional Plan is mentioned, available free for up to six months, and an invitation to sign up using the provided link is extended to viewers.

Keywords

💡Space Shuttle Orbiter

The Space Shuttle Orbiter refers to the orbital vehicle component of the Space Shuttle system, which was used by NASA for human spaceflight missions. It was capable of surviving the intense heat of re-entry and transitioning to aerodynamic flight. In the video, the Orbiter's re-entry is highlighted as a critical and unique aspect of its mission, demonstrating the engineering marvel involved in its design and operation.

💡Re-Entry

Re-entry is the process by which a spacecraft returns to a planet's atmosphere from space. It involves traveling through the upper atmosphere at extremely high speeds, generating intense heat due to friction with air molecules. The video discusses the Space Shuttle's re-entry as a challenging phase, where it experiences temperatures reaching 1650 degrees Celsius and forms a layer of superheated plasma around it.

💡Orbital Maneuvering System (OMS)

The Orbital Maneuvering System (OMS) is a set of engines on the Space Shuttle used for changing the orbit and attitude of the spacecraft. The script mentions a 2-4 minute burn of the OMS engines to reduce the orbiter's speed by 0.1 kilometer per second, which is crucial for initiating the re-entry process and ensuring the shuttle enters the Earth's atmosphere at the correct angle and speed.

💡Entry Flight Corridor

The Entry Flight Corridor is a narrow window of opportunity for a spacecraft to re-enter the Earth's atmosphere successfully. It involves balancing the spacecraft's speed and angle of entry to avoid overshooting or descending too fast, which could lead to overheating or missing the target landing area. The video emphasizes the precision required in the shuttle's re-entry to navigate this corridor.

💡Reaction Control System (RCS)

The Reaction Control System (RCS) is a set of thrusters on the Space Shuttle used for attitude control and maneuvering. The script describes how the RCS flips the shuttle around into a 40-degree pitch angle to prepare for re-entry, highlighting its role in orienting the shuttle for its encounter with the Earth's atmosphere.

💡Ablative Coating

An ablative coating is a sacrificial material applied to a spacecraft that is designed to burn away gradually, carrying heat away from the vehicle during re-entry. The video discusses the challenges faced with the ablative coating on the X-15, which was found unsuitable for the Space Shuttle due to its tendency to burn away unevenly and potentially obstruct the pilots' view.

💡Inconel X

Inconel X is a family of austenitic nickel-chromium-based superalloys, known for their excellent resistance to high temperatures. The script mentions that Inconel X was used in the X-15 but was too heavy for the Space Shuttle, which needed a lighter material due to its launch requirements. The contrast between the materials used in the X-15 and the Space Shuttle underscores the different engineering challenges faced by each vehicle.

💡Carbon-Carbon Composite

A carbon-carbon composite is a material made of carbon fibers bound together with a carbon matrix, used for its high strength and ability to withstand extreme temperatures. The video explains that the leading edges of the Space Shuttle's wings were made from this material, which could endure temperatures up to 1510 degrees Celsius, making it crucial for protecting the shuttle during re-entry.

💡Silica Tiles

Silica tiles are lightweight, heat-resistant tiles used on the Space Shuttle to insulate the vehicle from the intense heat of re-entry. The script describes how these tiles, made from silica fibers and coated with a glass material, were used to protect the shuttle's underside. The tiles' design and placement were critical for the shuttle's thermal protection system.

💡Elevons

Elevons are a type of control surface on the Space Shuttle that combine the functions of elevators and ailerons. The video mentions the use of elevons for controlling the shuttle's angle of attack during re-entry and landing, which is essential for managing the shuttle's trajectory and ensuring a safe landing.

💡Drag Shoot

The Drag Shoot is a parachute system used on the Space Shuttle to assist in landing, especially on shorter runways. The script describes its introduction on STS 49 and its role in providing additional drag to slow down the shuttle during landing, demonstrating the shuttle's need for precise control over its speed and trajectory.

Highlights

Space Shuttle Orbiter faces the most difficult part of its mission after 7 days in orbit: re-entry through the earth’s upper atmosphere.

The Space Shuttle was uniquely capable of surviving immense re-entry heat and transitioning to aerodynamic flight.

Re-entry involves a precise 2-4 minute burn of the OMS engines to reduce the orbiter's speed by 0.1 km/s.

The shuttle's wings generate lift during re-entry, crucial for avoiding overshooting or catastrophic overheating.

The entry flight corridor is a narrow window for a successful re-entry, avoiding speed extremes.

The Space Shuttle's design was influenced by the X-15, the fastest plane in history, for hypersonic flight understanding.

Inconel X, used in the X-15, was too heavy for the Space Shuttle, leading to the use of aluminum with a lower operating temperature.

Ablative coatings used in the X-15 were unsuitable for the Space Shuttle due to safety and reusability concerns.

The Space Shuttle's nose, wings, and belly were designed to minimize shockwave impact and associated heat.

Schlieren imaging reveals the effectiveness of the shuttle's design in managing shockwaves and heat.

The Space Shuttle uses a blunt body design to create a bow shock wave and insulating air layer, reducing heat transfer.

During re-entry, the shuttle experiences a communication blackout due to the plasma layer blocking electromagnetic signals.

The shuttle's body flap serves as a massive control surface and a heat shield for the main engines.

Reinforced carbon-carbon composite is used for the leading edges of the shuttle, capable of withstanding extreme temperatures.

Inconel attachment points and insulating tiles protect the shuttle's interior from the heat of re-entry.

The shuttle's tiles are carefully engineered and assembled like a puzzle, with specific shapes and thicknesses.

Nomex felt and flexible adhesive allow the shuttle's structure to flex without damaging the heat-resistant tiles.

Flexible heat shields made of silica and nomex fibers are used in areas of lower temperatures for easier replacement.

The shuttle's bank angle controls work in reverse at hypersonic speeds due to the interaction with compressed air.

Air data sensors are deployed at Mach 3 for the final approach, providing crucial flight data.

The Space Shuttle was designed with large delta wings to achieve the crossrange needed for a single-orbit return.

Pilots underwent intensive training using modified Gulfstream jets to simulate shuttle flight characteristics.

The shuttle's approach and landing procedure is carefully managed to ensure a safe touchdown on a long runway.

Onshape, the video's sponsor, offers a modern cloud-based CAD system for collaborative design work.

Transcripts

This video is brought to you by  Onshape. Try the professional  

plan for free for up to 6 months  with the link in the description

After spending 7 days in orbit around the  earth, the Space Shuttle Orbiter now has  

arguably the most difficult portion of  its mission to complete. A hell blazing  

journey through the earth’s upper atmosphere.  Where it will travel so fast that it will rip  

air molecules apart, forming a layer of  superheated plasma around the aircraft.

Re-Entry is where the Space Shuttle  truly became a one of a kind spacecraft.

The Space Shuttle was a radical  new idea. A spacecraft capable of  

not only surviving the immense heat of  re-entry, but capable of transitioning  

to aerodynamic flight, which required  careful moulding of its wings and tail,  

balancing the needs of unpowered glider  with the needs of a re-entry vehicle

This is the Insane Engineering of the Re-Entry

The Re-entry procedure begins with a 2-4 minute  burn of the orbital manoeuvring system engines  

while the space shuttle is upside  down and travelling backwards.

With an orbital speed of around 7 kilometres  per second, the OMS pods need to reduce the  

orbiter's speed by just 0.1 kilometre per  second. 1.3% of its velocity, to lower its  

orbit enough to bring it into a collision  course with the earth’s upper atmosphere.

A precise manoeuvre; bleed too little  speed and the orbiter will overshoot its  

narrow window for success, skimming through  the thin upper atmosphere and potentially  

bouncing back into space. The orbiter  has wings that generate lift, after all.

Bleed too much speed and the orbiter will  descend through the atmosphere too fast,  

reaching the thick lower atmosphere  before enough speed has been leached away,  

resulting in catastrophic overheating. This narrow  entry window was called the entry flight corridor.

Once the delicate retrofiring sequence has  been completed. The next phase of re-entry  

begins. The reaction control system flips  the shuttle around and places it into a  

40 degree upwards pitch angle, ready  to meet the earth’s atmosphere. [REF]

Entering the upper atmosphere at 30 times the  speed of sound. The speed is so great that it  

begins to rip air molecules apart, creating a  glowing cloud of charged plasma around the lower  

surface of the orbiter. With peak temperatures  reaching 1650 degree celsius (3000 F).

Nothing like this had ever been attempted.  A blunt body capsule, like every other  

re-entry capsule to date, designed purely for  thermal protection is an engineering challenge,  

but tack on the needs of an aircraft  and the task gets vastly more difficult.

Thankfully NASA had a test run in 1959  with the X-15. The fastest plane in the  

history of humankind, and it advanced  our understanding of hypersonic flight,  

providing many lessons that were  incorporated into the space shuttles design.

However the X-15 had one major advantage over the  Space Shuttle. It didn’t need to launch itself to  

orbit. It didn’t even launch from the ground.  Instead launching from the belly of a B-52.

This allowed the X-15 to use a state of the  art advanced heat resistant aerospace metal,  

inconel X, with a max operating temperature of 980  

degrees celsius (1800 F). The Space  Shuttle could not use this metal.

Inconel X is too heavy, about 180%  heavier than an equivalent aluminium  

airframe. A massive issue for an aircraft  designed to be carried to orbit. [REF]

The Space Shuttle’s airframe therefore is not  made from inconel X. It is composed of lightweight  

aluminium, which has a max operating temperature  of just 177 degrees. 5 times lower than Inconel X.

The orbiter would experience temperatures 10 times  

greater than this for extended  periods of its re-entry flight.

To make matters worse, one of the  principle lessons learned during  

the X-15 program was that the hot pink foam  ablative coating sprayed onto the plane for  

top speed flights was completely  unsuitable for the space shuttle.

An ablative coating is a sacrificial  material designed to gradually burn  

and fall away from the aircraft,  pulling the heat away with it.

However, the ablative coating of the X-15 had a  nasty habit of burning away from the nose of the  

plane, and begin attaching itself to the cockpit  windows, rendering the pilots completely blind.

Which presented a bit of a problem. At one  point the engineers of the X-15 considered  

attaching a small explosive to the window, and  intentionally exploding the outer pane of glass  

to remove the ablative stained window,  leaving only the inner pane for landing.

Thankfully they came up with the much less  risky solution of installing a mechanical  

eyelid to the left window that remained  closed until the high speed portion of  

the flight concluded. Providing the pilot  one clean window to land with. An extremely  

primitive solution that created stability  issues as the open eyelid acted like a canard,  

causing the plane to pitch  up, roll right and yaw right.

Even more terrifyingly, this coating  became explosive when mixed with liquid  

oxygen and could be triggered by even a  slight impact. A massive safety concern  

for a plane that required a liquid oxygen  oxidizer to operate. A danger that would  

be multiplied many fold with a vehicle filled  with half a million litres of liquid oxygen.

The ablative was also not reusable, which  would drastically increase the cost of  

refurbishing the shuttle between flights.The  space shuttle would need to be better.

As the space shuttle descended  through the atmosphere its nose  

and wings bore the brunt of the re-entry heat.

The high pressure shock waves forming around  them have created a layer of superheated plasma,  

if this heat managed to find its way into the  delicate aluminium framework inside the orbiter,  

it would be game over. This is exactly  what happened to the Columbia shuttle  

as a result of damage to the  leading edge of these wings.

The first step to protect the  orbiter's surface was to keep  

this super heated plasma as far away  from the surface as possible. The nose,  

wings and belly of the orbiter was carefully  crafted to ensure shockwaves were kept at bay.

We can see how using schlieren imaging.  A pointed missile-like vehicle pierces  

through the air with efficiency and  in doing so creates a shock wave,  

attached to its nose at an angle  determined by its mach number.

This shockwave is simply a region  of incredibly high pressure,  

and with that pressure comes  incredibly high temperatures

This can have disastrous effects, as DARPA  experienced twice in 2010 and 2011 when  

testing their sharp nosed hypersonic  reentry vehicle. The HTV-2. Within 9  

minutes of re-entering earth's atmosphere,  both vehicles disintegrated as a result of  

the 1930 degree heat penetrating their  metallic skin. The HTV-2 completed its  

mission of collecting hypersonic flight  data, but the space shuttle needed to  

not only survive this mode of flight, but to  do it repeatedly with minimal refurbishment.

A good portion of this heat could be  kept away from the aircraft skin with  

blunt body design.Which creates a rounded  bow shock wave with a layer of insulating  

lower pressure air between the vehicle and  the shockwave. Reducing heat transfer rates.

For this reason the Space Shuttles surface is  carefully moulded to take advantage of this  

phenomenon. The rounded nose cross section  gradually transitions to a blunted triangle.

This shape minimised the heat reaching the  less protected side wall of the shuttle,  

which used lower temperature insulation.

We are now 7 minutes into the re-entry procedure,  having descended 50 kilometres in altitude,  

but only shedding 0.5 kilometres per second  off our velocity, we have entered the period  

of maximum reentry heat. A confluence  of speed and atmospheric density.

The layer of superheated plasma surrounding  the shuttle is blocking communication to the  

computers and astronauts inside. A result  of free electrons in the plasma interfering  

with electromagnetic communication techniques. A  problem that would last for the next 12 minutes.

For now the shuttle is operating on its own  telemetry data. Ensuring that a 40 degree angle  

of attack is maintained. Managing that angle with  a velocity of 6.5 kilometres per second was no  

easy task. A massive control surface was needed.  The elevons on the outer wing would not suffice.

This is where the rear body flap came into  play. It was a massive control surface  

underneath the shuttle's main engines,  covered in high temperature insulation.

The body flap doubled as a  heat shield for the shuttles  

main engines. With no cooling liquid  hydrogen running through the nozzle,  

the flap was needed to shield the  engines from the heat of re-entry.

On the Space Shuttle’s third flight the Kuiper  Airborne Observatory flew underneath the orbiter  

as it re-entered and captured an infrared image of  its searing hot belly. An experimental program to  

validate NASA’s newly developed computational  calculations and experimental testing.

This is what it saw [REF] The nose and leading  edges are a scorching 1500 degrees celsius. Far  

beyond what the Aluminium airframe  underneath is capable of enduring.

These leading edges, experiencing the hottest  temperatures, needed the most heat resistant  

material on the entire shuttle, a reinforced  carbon-carbon composite. One of the amazing  

materials created in the years between the  development of the X-15 and the Space Shuttle.

A carbon composite manufactured  with a special post processing step.

It was initially manufactured like any  other carbon fibre part. A carbon fibre  

weave moulded into shape and bound  together with a resin. However,  

the heat of re-entry would  set the hydrocarbon resin on  

fire without special treatment. The post  processing step would solve this problem.

The carbon composite is placed in a  vacuum chamber and heated, causing  

the hydrocarbon resin to decompose, releasing  the hydrogens, leaving layers of pure carbon  

behind. Graphite. Carbon fibres bound together  by a maze of graphite. Strong, and capable of  

withstanding 1510 degrees celsius. They face  head on into the inferno of hypersonic flight.

The leading edge of the orbiter's wings  is composed of 22 of these carbon carbon  

panels. With sealing strips covering  expansion gaps between each panel,  

an essential solution to a lesson hard  won during the development of the X-15.

To investigate the heat of hypersonic  flight the X-15 was painted with a  

special kind of paint that reacts to heat,  and after one flight the X-15 returned with  

strange wedge shaped patterns emanating  from the leading edge expansion joints.  

Small gaps in the leading edge to allow the  inconel skin to bend and contort with the  

wing without buckling. This localised heating  was happening as a result of turbulent flow,  

increasing the rate of heat transfer to  the metallic skin of the aircraft. To fix  

this small floating strips of inconel  were placed over the expansion gaps..

These strips of reinforced carbon  carbon serve the very same purpose.

However, there was one more problem. Carbon is a  

thermally conductive material,  not ideal for a heat shield.

The space shuttle has been travelling  through the atmosphere for 15 minutes,  

but is still travelling at 6 kilometres  per second and contact has not been  

reestablished through the cloud of  plasma surrounding the aircraft.

This is a sustained heat, and  with carbon being conductive,  

this heat could make its way to the  aluminium airframe over this period of time.

If these carbon carbon shields were attached  directly to the airframe the heat would come  

into direct contact with the metal, raising  it above its max operating temperature.

To prevent this the panels were fitted with  inconel attachment points that attached to the  

aluminium airframe with inconel bolts.  Inconel, being mostly made of steel,  

is a poor conductor of heat and could handle  the heat the carbon parts transferred to it,  

without easily transferring  that heat to the aluminium.

This wasn’t enough to protect the  interior of the shuttle however,  

a layer of insulating tiles were placed  underneath the carbon carbon shield too.  

The same insulation that was used on  the underside of the entire orbiter.

The Space Shuttle Columbia had 32000 of these  tiles, in two flavours, low temperature and high  

temperature, white and black. Both of these  tiles were made from the same base material.

Silica fibres just a few millimetres thick,  which by volume made up just 10% of the tile,  

the remaining 90% was nothing by air.  An excellent insulating material,  

a thick and light tile, composed of a  material with a high operating temperature.

The coating is where the tiles differ. The black  tiles, installed on the lower portion of the  

shuttle, were covered in a black borosilicate  and tetraboron silicide glass coating.

This black coating helps dissipate heat  before it can conduct into the vulnerable  

inner structure. Black for the same reason the  SR-71 is black. Kirchoff’s Rule of Radiation.

This rule tells us a good infrared heat absorber,  

basically any black object, is also an equally  effective heat emitter. With the heat gained  

from hypersonic flight vastly higher than  the heat gained from solar radiation, it’s  

preferable to prioritise outward heat radiation,  than minimising heat gained from solar radiation.

So why isn’t the entire space  shuttle black, like the SR-71?

The shuttle has one important difference with the  SR-71, it exited earth’s atmosphere. Once outside  

the earth's atmosphere the intensity of solar  radiation increases drastically, with the longest  

orbiter mission at 17 days, this heat had plenty  of time to conduct through to the people inside.

The orbiter did have huge radiator panels to  reject heat to space, but to minimise their  

size we want to reflect as much of that heat back  into space, and for that reason they are white.

These tiles were coated with  a similar glass coating,  

but with an aluminium oxide additive  to provide the white colouring. The  

coatings also helped to waterproof  and strengthen these porous tiles.

The tiles were assembled like a giant precisely  engineered puzzle with 32,000 pieces. Each tile  

assigned a serial number that corresponded  to their location, shape and thickness.

The tiles were created by mixing cotton like  silica fibres with water, this mixture was  

then cast into large blocks, and were then  dried in a microwave oven. Once dried they  

could be cut into smaller sheets. [Footage] The tiles varied from 25 millimetres to 127  

millimetres thick. With the 127 millimetres  tiles insulating up 1280 degrees celsius.

These sheets were then into their precise shapes,  

according to their assigned serial numbers,  using a computer controlled milling machine.

We are now coming through the end of  the communication blackout, and enough  

of the heat of re-entry has reached the aluminium  airframe to cause it to expand. A major problem as  

these tiles are not flexible in the slightest,  and are quite fragile. The expanding airframe  

could easily break the tiles and open up a path  for the superheated gas to penetrate inside.

The engineers needed a way  to allow the structure to  

move beneath the tiles without  causing the tiles to pop off.

To do this, the tiles were first glued in  groups to a layer of flexible nomex felt.  

This nomex fabric allowed the structure beneath  to flex, expanding the lower side of the felt,  

without transferring that strain to  the upper layer attached to the tiles.

These tiles and felt were then attached  to the shuttle using the same adhesive.  

A commercially available high temperature RTV  adhesive. A bright red silicone based adhesive.

To prevent collisions between tiles,  

gaps between 0.64 millimetres and  1.9 millimetres were included.

Thankfully the issue of turbulent flow created  by expansion gaps primarily affected the leading  

edges of the wing, so these gaps were not  covered on the exterior of the shuttle.

In areas exposed to lesser temperatures flexible  heat shields were used. Constructed from high  

temperature silica and nomex fibres to create  a flexible fabric which were sewn together  

with the same fibres, giving a quilted blanket  appearance. With the nomex fabric capable of  

resisting temperatures up to 370 degrees and the  silica fabric capable of tolerating temperatures  

up to 650 degrees. These were lighter and  easier to replace than the tiles. Being  

bonded directly to the structure once again  with that bright red silicone RTV adhesive.

We are now out of the communication black out  and approaching 4 km/s or mach 12 in velocity  

and are about 45 kilometres in altitude. About  4 times the cruising altitude of an airliner.

The orbiter has maintained that 40  degree angle of attack this entire  

time. [Page 239]. Being forced to hold an  angle of attack this large comes with some  

control problems. The orbiter needs to  land precisely on a landing strip from  

orbit. Managing its trajectory while being  stuck with its nose up would be difficult.  

Especially for a glider with no way to add  energy once its been bled away by drag.

If the Space Shuttle wanted  to lower its lift and lower  

its altitude faster it could  not lower its angle of attack,  

So the shuttle needed a special way to adjust  its trajectory to target its landing area.

Instead the orbiter decreased  its lift by banking. This split  

the lift into vertical and horizontal  components. Reducing the lift keeping  

the shuttle in the air and trading  it for lift that moved it sideways.

This is what a typical re-entry flight profile  looked like. This line is the angle of attack,  

keeping steady up until Mach 12  and then gradually reducing as it  

descends through the thick lower  atmosphere. And this is the bank  

angle. As the orbiter crashes down from  orbit, it banks wildly from side to side.

The astronauts inside, who are already  pointed 40 degrees up, are not tilted  

on their sides up 70 degrees. The orbiter is  essentially doing the fastest drift in history.

There are some quirks of flying this high  in the atmosphere at hypersonic speeds.

The bank angle controls actually work in reverse  to normal. If we deflect the right elevon down,  

it should increase lift on the  right wing and cause that wing  

to rise, banking the aircraft  anti-clockwise, but it doesn’t.

When the elevon is deflected downwards, into the  already compressed hypersonic air it causes drag  

to rise on the outer wing. This causes the  orbiter to turn its nose in that direction.

As the nose turns in the direction of the  deflected elevon, it shields that wing  

and causes a decrease in lift, causing  the shuttle to bank in that direction.

So, where a downwards deflecting elevon would  typically cause an increase in lift on the wing,  

here, through a series of events, it  causes a decrease. Working in reverse.

Ofcourse this bank angle causes  the Orbiter to drift off target  

for its landing and to correct  it needs to bank the other way.

The orbiter has now slowed down to Mach 3,  

and at this point flight crew deploy air data  sensors to aid in the final approach. [Page 418]

Two probes rotate from underneath the  heat shield on either side of the nose,  

providing air speed, angle of attack and  temperature data to the flight computer.  

At this point the orbiter is flying like a  plane, but it’s not a plane, it's a glider  

and the flight crew needed to carefully  manage the remaining energy to land safely.

Especially as the orbiter is not built like  a traditional glider. Balancing the need to  

survive reentry, while maximising lift efficiency  was a unique engineering challenge, made more  

difficult by Air Force funding causing the design  to skew closer to a plane than a re-entry vehicle.

Early concepts of the shuttle  drew inspiration from the X-15,  

with much smaller wings. More than enough to  land the original smaller orbiter on a runway. 

The air force wanted a larger payload capacity,  

and they had one more specific requirement  that required bigger wings. They wanted  

the Space Shuttle to be able to take off  from Cape Canaveral, complete its mission,  

and land back at Cape Canaveral after  a single orbit. Essentially treating  

the space shuttle like a military operation  to avoid Soviet attention, fast and elusive

This came with some issues.

A single orbit took 90 minutes, in which  time the earth rotated below the shuttle’s  

orbit by 2000 kilometres. So, to return  to its launch location the orbiter would  

need to be capable of flying laterally by  at least 2000 kilometres. This is called  

crossrange. The original X-15 inspired design  was capable of just 370 kilometres of crossrange.

North American Rockwell proposed this huge  blended body delta wing concept in 1970  

which would have given the orbiter 2800  kilometres of crossrange (1500 nautical  

miles). The full reusable concept,  with its crewed booster rocket and  

internal fuel tanks were not to be,  but the large delta wings endured.

These delta wings provided enough lift in both  hypersonic, supersonic and subsonic flight  

regimes to provide the cross range needed to reach  the original launch site after a single orbit.

Despite that, the space shuttle was an  unwieldy aircraft, and with no powered flight,  

the commander had one shot to land it safely.  So they had to go through intensive training.

In 1973 NASA created 4 training aircraft by  modifying 4 gulfstream jets to fly like the  

space shuttle. [REF] In order to mimic the  immense drag the blunt body design of the  

space shuttle would create, the gulfstreams flew  with their landing gear down, with their engines  

working in reverse, and flew with their flaps  deflected upwards to decrease lift. [Footage]

With flight characteristics like this the  space shuttle needed to carefully manage  

its energy. Losing too much altitude far  from the runway would be far from ideal.

The pilots aim, guided by beacons and  ground control, for a tangential entry  

into a circular approach path 5800 metres  in diameter just off the runway. The  

moment they intercept this circle the space  shuttle commences a deep spiralling turn.

At this point the space shuttle is still  travelling at about 0.8 mach. Still very fast,  

and it's at this point the wings are stressed  the most. Hitting a higher max dynamic pressure  

than at any point during the re-entry process  due the higher air pressure at this altitude.

And the shuttle's descent rate increases,  

now losing altitude rapidly with the knowledge  the runway is within a safe gliding distance,  

descending to about 3000 metres in  altitude and slowing to about 0.5 mach.

At this point the Shuttle enters a straight  

20 degree glide approach path.  Much steeper than any airliner.

Bleeding speed as needed using the  split rudder speed brake. The rudder  

on the vertical tail wasn’t just used for  controlling yaw by deflecting left and right,  

it could split in two, deflecting outwards  to a maximum of 62 degrees on either side.

The gear is lowered as late as possible  and in the final moments before touching  

down the commander will increase the  angle of attack of the shuttle using  

the elevons in order to slow its  descent rate before touching down.

At the moment of main gear touch down  the speed brake is commanded to fully  

open. At this point the shuttle is still  travelling at 360 kilometres per hour,  

close to 0.3 mach, and there is  plenty of braking left to do.

The runway at Cape Canaveral is 4.6 kilometres  long, much longer than your average runway. With  

typical 3 kilometres long runways being able to  deal with the heaviest of jumbo jets landing.

As the nose gear touches down the  electro-hydraulic brakes in each of  

the 4 main landing gear wheels are fully engaged  by application of the foot pedals in the cockpit. 

Each brake assembly had nine  carbon-lined beryllium discs,  

four rotors, and five stators, which were  pressed together to provide braking force.

On STS 49, Bruce Melnicks mission, an  additional braking mechanism was introduced,  

hidden away underneath the vertical tail speed  brake. The drag shoot. STS 49 was the maiden  

flight of both the endeavour and the drag  shoot. An explosively deployed parachute, you  

can even see the parachute door and sabot being  flung from the back of the shuttle on landings.

It was designed to allow the Space Shuttle  to land on a shorter 2500 metre runway,  

a contingency plan in the event  the space shuttle had to abort  

a launch and land on a runway on  the other side of the atlantic.

For each and every launch NASA sent staff  to these predetermined landing locations,  

like Fairford RAF base in Gloucestershire,  

England. A large team was needed to assist with  the final moments of each space shuttle mission.  

And these teams were not once needed in the  entire history of the space shuttle program.

A giant fan was even rolled out on the runway  to help disperse any potential toxic chemicals,  

like the hydrazine fuel, away  from the shuttle. [FOOTAGE]

The mission is now over. The crew has disembarked  and the space shuttle will be refurbished and  

flown back to Florida on the back of a  747 in preparation for its next mission.

People often say how incredible it is that  older aerospace and aviation projects like  

this were designed with pen and paper. Hand  drafted technical design was an art form,  

and a labour intensive art form at that.

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