Fighter Flight: The Sky's The Limit

The Naked Scientists take flight through the history and science of fighter aircraft.
17 July 2018
Presented by Chris Smith, Izzie Clarke
Production by Marika Ottman.

In Flight Formation

In Flight Formation


We hope you’ve got your boarding passes at the ready, because to celebrate 50 years of the jumbo jet, 100 years of the Royal Air Force and the recent arrival of the brand new F35 fighter jet in the UK, The Naked Scientists are taking a flight through the history and science of fighter aircraft. Plus, in the news, a new way to fight cancer… by giving people cancer! How virtual reality can combat a fear of heights, and we shed some light on the hearing aid of the future!

In this episode

Headline about cancer

01:01 - Fighting Cancer with Cancer

If someone told you that they wanted to treat your cancer by injecting you with more cancer cells, you’d be right to be sceptical.

Fighting Cancer with Cancer
with Khalid Shah, Harvard Medical School

If someone told you that they wanted to treat your cancer by injecting you with more cancer cells, you’d be right to be sceptical. But that’s exactly what researchers at Harvard Medical School are doing, because they’re exploiting a natural tendency of cancer cells to home back in on their parent cancer deposits, or join into sites of cancer spread, called metastases. Khalid Shah has developed a way to genetically engineer harvested tumour cells to make them churn out therapeutic “death signals” so that when the cells are reinjected into the body, they seek out tumours and trigger nearby cancer cells to kill themselves. As a safeguard, the modified cancer cells have an in-built “kill switch” so they can be terminated once their job is done, as Chris Smith found out.

Khalid - One of the major hurdles for advance stage cancer is that they're localised but they also move from one organ to another. They also can move from the other organ back to the same place where they originated and we can sort of repurpose the tumour cell homing properties for delivery of targeted therapeutics to the primary tumour cells.

Chris - So are you saying then clearly that what you can do is take a cell from a tumor that wants to get back to its home tumor, and do the equivalent of say brainwashing a terrorist and releasing that terrorist back onto the street, to lead you back to where he came from or she came from?

Khalid - Yes, you're right. So we can actually tame a cancer cell. We actually re-engineered it to produce therapeutics and then kill the original tumour cell. How on earth did you do that. So we used two properties, let's assume you have two cancer patients; one has a cancer resistant to a particular drug, and one has cancer sensitive to a particular drug.

What we did is we took the tumour cell that is resistant to a particular drug and engineered it to release therapeutics that can kill the tumour that is sensitive to that drug. The second approach is that we took the patient's own cells, which sends it to a particular therapy and we gene-edited its surface receptors to make them resistant first, then engineered them with therapeutics and a “killswitch”. With the therapeutic, we can kill the original cell and with the killswitch we can kill the re-engineered cell.

Chris - This is neat. Basically you're using the natural homing behaviour of cancer cells to get into tumors that have spawned cancer cells that are trying to spread around the body. When they go back into the tumor, they detonate an explosion that's going to kill the parent tumor but you've also put a safeguard in there which is that you can kill the cells you’re putting back in because you've got this additional, as your dubbing it, “kill switch” engineered in there.

Khalid - Yes. The beauty of the killswitch is also that it can be imaged by PET imaging so we can actually track the re-engineered cell in the body.

Chris - How do you endow the cancer cell with the ability to kill the parent cancer but itself not be killed by the toxic cargo it's carrying?

Khalid - Cancer cells have these unique signatures on their surface that make them cancer cells. One of them is death receptors on the surface of the tumor cell. What we did with gene editing technique is that we knocked out the receptors on the surface of the tumour cell. So it's not killed by therapeutic it's producing.

Chris - These cells that you infuse, can they access all areas? Can they both go to the parent tumor, that spawned the person’s disease and it's spread, and could they potentially also therefore access the metastases where it spread to?

Khalid - Yes, we have tested this in mice and we've shown that if you inject them into the primary tumour site they can eradicate that primary tumor cells. We also injected them systematically in one of the arteries that leads to the brain and we can show that they can track and can kill metastatic tumour cells in the brain as well.

Chris - It might worry some people though the prospect that you're injecting people with not just a genetically modified cell, but a genetically modified cancer cell. Are there no risks associated with doing this?

Khalid - Absolutely. I don't think it will be taken without a grain of salt because you're putting cancer cells back into the patient. I think the first indication would be going into the tumors cells which have an unmet need where we haven't done anything for last two decades. One of the prominent tumours is the brain tumour where the survival is between 12 to 18 months post diagnosis. So yes, if we can assure people that we have the engineer tumor cells under control and we can kill them any time, I think the first indication would be in the most unmet need tumours.

Chris - And is there no risk that the infused modified cells could go rogue and undo the killswitch you've engineered into them and then you've actually given that person an even worse prognosis

Khalid - No, because we use anti-viral vectors that integrate into the genome of the cell. So whatever we have engineered the gene that we have engineered is incorporated into the genome and the cells so there's very low chance of these cells going rogue and leaving the gene out.

Old mobile phones

E-Mining: Turning your mobile into money
with Peter Cowley

Now what do you do with old and dead gadgets, like TVs, computers and phones? Most people just throw them away and many end up in landfill. But, on a global scale, are we throwing away a fortune? Many people think so, including Sydney-based materials scientist Veena Sahajwalla, who’s pioneering what she dubs an “urban mine” at the University of New South Wales to recover precious metals from discarded gadgets. To take a look at the numbers, Chris Smith and Izzie Clarke were joined by Tech expert and Angel investor Peter Cowley, so what should we be looking for? 

Peter - I think we're primarily talking about smartphones here although the academic mentioned CRT, cathode ray tubes. If you take a smartphone, they build high end ones probably about $200 or $300 but the low end is only $40, the total amount of recyclable materials, the biggest of all in terms of value, is gold. But on average only 31 milligrams each phone, which works out to about $1.20, silver are much more, about 150 milligrams, copper at 15 grams. But copper’s pretty cheap you know, about 9 cents per phone. If you take everything out of the phone, you're only talking about $1.30 or something like that from the whole lot. The best use of a phone is actually to refurbish it and to recycle it and put it back into use rather than to break it down, I think.

Izzie - How much is it all worth, the materials that we're looking at here?

Peter - Well the lady in Australia has come up with a number of about £300,000.

Chris - Just to clarify, what do you mean by £300,000?

Peter - This was the capital cost of the equipment.

Chris - So that's what it cost her to start doing this.

Peter -  Exactly. To produce some equipment, which I think is probably based on a furnace which will then separate out the metals, if it can do. So you will need about 100 phones now and of course 100 phones now is quite a lot of transport involved with that so rt of thing. So is that worth it? I'm not sure. There’s another wonderful robot called Daisy, humbly named after 2001: A Space Odyssey, Howl, if you remember when it was being switched off it sang Daisy. Apple has produced disassemble phones. Now whether it’s done for the reason, I'm not sure, whether it's actually recycling or not.

Chris - So you're saying there's a £300,000 upfront capital cost in setting up your infrastructure to strip out phones and recover the materials. So if you're reckoning you're getting pence per phones worth of precious metals back, there are 7.5 billion phones on Earth and that's just phone, so there are lots and lots of materials that could potentially be scavenged this way. Do you not think it's a viable business model?

Peter - That depends on a number of factors, doesn't it. It depends on bringing back the device to somewhere where it's processed. There is something called the WEEE Directive in Europe which means a manufacturer has to take back the device and then recycle it or dispose of it correctly. It's been around about 15 years now. And I've electronics business that has to do that occasionally. So to get it back, the capital equipment cost of the equipment to do this, the processing costs etc., refining it and then redistributing back into the supply chain. If you take that phone, you've probably got to say $1.30 out of it. You know, $1.30 is going to cost you the best part of that just to get the phone back to processing plant. I would think. Another fact you should take into account, the landfill costs are in the UK £90 a ton. I'm not quite sure what the volume of a tonne is but because there are about 8,000 or 10,000 phones in a tonne, you're talking about a penny, the cost of actually disposing it, which is completely the wrong thing to do, clearly. I mean absolutely positive about the secular economy in recycling.

Chris - How do you actually get the stuff out of the phone?

Peter - I have a phone here in front of me which obviously the listeners can't see.

Chris - It doesn’t look like it would work very well anymore. 

Izzie - Looks like it’s been dropped on a night out.

Peter - This is actually an iPhone 3 so it's a long time ago. And if you look at it, the amount of gold is really very small. What would be very useful, of course, the most expensive item in the phone is the screen. But you can only do that by the way of recycling it. What the lady is talking about in Australia is taking the precious metals out of it. There's no doubt that as a set of component parts, it's got more value than the raw materials inside it.

Chris - Oh really? So it’s not worth it, grinding it up and getting the bits out. You actually want the components.

Peter - I don't believe it is because if gold was 40 times more, and it's $40,000 a kilo anyway, if it was 40 times more expensive than it would be different.

Chris - Because one figure I saw was that if you look at how much gold comes out of the ground in terms of how much you have to move to get a gram of gold or so. I was in Kalgoorlie in Western Australia. I watched trucks going by with 250 tonnes of ore on board. And they told me it can take up to 4 of those to get 1 golf ball sized hunk of gold at the end of the day.

Peter - Yes.

Chris - Whereas these gadgets, some statistics are suggesting actually the recovery rate might be much much higher. 350 grams per tonne of phones than 9 grams per tonne of ore.

Peter - No, I think that figure is based on CRT, cathode ray tubes, I think her figures are based on 5 grams of gold in the CRT. These are in old fashioned televisions, game arcade machines, and air traffic controllers probably still use them as well.

Chris - So is it a no from you then Peter?

Peter - I’m out, yes. I would not invest in it.

A green laser

The hearing aid of the future
with Marcus Jeschke, University Medical Centre in Göttingen

You might want to hear this! Scientists in Germany have invented what’s being dubbed the hearing aid of the future: it uses light to deliver information about sound to the nervous system. Chris spoke to Marcus Jeschke, from the University Medical Centre in Göttingen, who is one of the developers.

Marcus - So normally, sounds that reaches our ears are transmitted through what's called tympanic membranes. So that’s a small membrane that uses the vibration that's caused by sound and is transmitted into the structure in our inner ears called the cochlea. Here there is very tiny hairs cells who transmit this movement into electrical signals that our brain can understand. Close to the base of the cochlea neurons and hair cells preferentially respond to high frequency sounds, whereas at the apex or tip of the cochlea neurons and hair cells preferentially respond to low frequency sounds.

Chris - And when someone has hearing impairment, what has gone wrong with that system you just described?

Marcus - So the most common form is the loss of sensory hair cells. This is usually caused by very loud sounds. This can also be caused by antibiotics and a couple of other factors.

Chris - And how do the present generation of hearing aids surmount the loss of those hair cells then?

Marcus - the current version, which is the electrical cochlear implant uses electrical current to stimulate the auditory neurons that are sitting behind the hair cells. These nerves are still excitable, so we can activate them by inserting a small cable with multiple electrodes that are sitting along different parts of the cochlea and they stimulate different parts of the auditory nerve, which is responsible for different pitches.

Chris - So the cochlear implant is listening to sounds coming to you from outside, and when it hears a high frequency it sends electricity to the wire that stimulating the high frequency bit of your cochlear, and the converse if you hear low frequency it sending signals preferentially down the wire that stimulates the low frequency bit.

Marcus - That is absolutely correct.

Chris - So what's wrong with that. Why do we need a next generation hearing aid?

Marcus - There's actually nothing wrong with that per se. It's the most successful neuroprosthesis we have. It's an amazing success story, it allows around half a million people that are implanted with cochlear implants to understand speech and quiet environments. However these patients still have problems understanding speech and noise and typically, don't appreciate music. The reason for that is hair cells in the cochlea sit in a very saline environment and that means that if you stimulate a certain part of the cochlea, this electrical stimulation spreads to neighboring parts of the cochlea and co-activates them. In other words it's as if you were playing the piano with your forearms.

Chris - Yes you're going to take down lots of notes at the same time rather than one finger, one note.

Marcus - Yes.

Chris - So what can you do that's better?

Marcus - One way to do this, is to use light. Light can be much more precisely confined. So you could use a very small dot of light, which is just a few microns, which is on the order of single neurons in our brain. And this allows many many more frequency channels or individual stimulation channels and this in turn could mean that you have access to the individual keys on the piano.

Chris - So what you're saying is you could thread, like a miniature string of fairy lights down the inside of the cochlea rather than just individual electrodes, and illuminate bits of the cochlea. But how do you make it sensitive to light? Because at the moment it's sensitive to electricity.

Marcus - That's correct. In order to do this, we use what's called optogenetics. So what we're doing is packing the genetic information of, if you want, lights switches into the neurons of the auditory nerve and therefore make them light sensitive. So what they will do is, upon light stimulation, these lights switches will activate, and in turn activate the auditory neurons.

Chris - And does it work? It sounds ingenious.

Marcus - It does work indeed. That's the cool thing about this. We have been able to show that in Mongolian gerbils, we can actually use these light switches and put them into the auditory nerve of adults, and show that upon light stimulation in the cochlea, these animals actually can use this light information to perform a behavioral task. So in other words, these animals,now hear light.
Chris - And you can prove that they do genuinely respond as though they're hearing a sound?

Marcus - That's right. We trained animals to respond to auditory stimuli before they were actually optically stimulated. And they learned to respond to certain sound, and react on this. And upon light stimulation, after they've learned this auditory behavior of sounds, a few animals transferred this to light stimulation.

Chris - Do you think this could be translated to humans?

Marcus - That's actually our goal, yes. Of course there's a lot to be done before you can actually safely try this in humans but in general, the idea is that this could work in humans, yes.


17:46 - A virtual therapist for real fears

Have a fear of heights? A virtual reality therapist could help...

A virtual therapist for real fears
with Daniel Freeman, University of Oxford

Picture the scene - you’re swaying on a rickety rope bridge slung 500 feet above a canyon. A gust of wind sends you swinging alarmingly; and the creaking noises issuing from the supporting ropes are far from reassuring… Are we making you nervous? If so, you might be one of the approximately twenty percent of us who suffer from a fear of heights. Surprisingly though, few of us actually seek any treatment for this. But this could soon change, because a team at Oxford University are developing a VR - or virtual reality - therapist, that could see you facing your fears from the comfort and safety of your living room. Isabelle Cochrane heard how from Daniel Freeman…

Daniel - When someone's overcoming a mental health problem, what you want them to be able to do is go into the situations that trouble them and feel fine about it. But normally when you have a mental health difficulty, for example feeling socially anxious going into a room full of people is difficult, for a fear of heights going to a height is difficult and what we can do in VR is present these situations and train the person in the moment how to overcome their difficulties.

Isabelle - So how does this VR compare with the treatment someone with a fear of heights for example would normally get?

Daniel - In many ways the treatment we would provide with VR is very similar to what you would get if you were seeing a highly skilled therapist doing the best psychological treatment. Because what we've done is try to automate the provision of really good treatment in VR so you don’t have the difficulties of trying to find a therapist, but in VR we also do some stuff that you can't do with a real therapist. We do things by virtual heights that push the fears a bit more than we might in the real world so we have like a platform that goes out in the middle of a large atrium where you rescue a cat. You wouldn't do this in real therapy but can do it in VR and when you can conquer these things in VR then it makes everyday situations around heights a lot easier.

Isabelle - Even just hearing about that platform makes me feel a little bit queasy I have to say.

Daniel - Yes I mean it's hard work. The thing about it is that the people that you know with fear of heights are sweating and it takes a lot of courage and determination. But at the same time, they're also smiling because they know it's not real. That's the beauty of it, you know it's not real, you do things that reward you would struggle with it, and you also have this added delight to find actually conquering it in VR transfers to the real world.

Isabelle - How realistic does it actually have to be in order to trigger this feeling of fear?

Daniel - It doesn't take much in VR to trigger a fear of heights. We’re very keen on making sure that things are engaging and appealing. So we're going for a reasonable amount of realism and we're also putting lots of fun elements in. Mental health treatments traditionally can be less than fun and we're trying to make something that's really engaging and appealing for people to help them overcome their problems, even rescuing the cat from the tree. Many people really quite enjoy that task.

When I do it, it certainly makes me very anxious. You’re 10 stories up basically on a plank trying to pick up a cat that is meowing at you, but people can also see the sort of comedic value of this as well.

Isabelle - What else do you get people to do?

Daniel - We do a bit of xylophone playing right by the edge of the virtual height for example.
And at the end when you've done all of the therapy tasks you get a chance to write a virtual whale around the atrium.

Isabelle - So that's your reward! How well does it work?

Daniel - Really well. Even I was surprised how good the results are. The average reduction in fear of heights was two thirds patient to the treatment which is extraordinarily good.

Isabelle - How are you measuring that?

Daniel - We use three different clinical assessment scales which can be validated against reactions at real heights. In other work we've done we actually take people to real heights before and after and you can just see the change.

Isabelle - Do you think we'll be able to use this for other phobias? So for example insects I think is quite a common one.

Daniel - Yes. I mean I guess Oxford our ambitions are much greater than just phobias, because we think it could be applied to most mental health conditions. We're working on a project that uses VR automated delivery of psychological therapy for patients with severe mental health problems such as schizophrenia. There are very few mental health conditions where you can not see VR as one aspect of care.

A lot of patients with severe mental health problems through current treatments still have quite a few problems. They’re often mistrustful, they might be hearing voices, they might be feeling depressed or socially anxious. The end result of all of this is that when they go into the real world for example around other people, everyday social situations they get very frightened and that means actually what they tend to do is draw from life, stay indoors. So again what we're dealing with here is helping people go back into everyday situations and learn that they're safe and that they can cope.

Isabelle - So how are you planning to make this available? Is something that you're planning to use in the context of clinics for example or is it just something that anyone will be able to download onto their smartphone or their VR device?

Daniel - Well it's a good question and I think the answer may change over the years. What we plan to do is to put it into an NHS psychological therapy service so the equipment is there, but of course as the kit becomes more widely available at home and it becomes lighter and more affordable and technically better, it will be like living in people's homes and you can envisage in the future people also doing these sorts of treatments in their comfort at home whenever they want.

Newton's Cradle

Celebrating Sir Isaac Newton's Principia
with Professor Lord Martin Rees, Astronomer Royal and University of Cambridge

There are some books so important that they revolutionise science. For physics, the pivotal text is Sir Isaac Newton’s Philosophiæ Naturalis Principia Mathematica - the Mathematical Principles of Natural Philosophy - which was published in this month in 1687. So to celebrate its 331st anniversary, Izzie Clarke visited another important scientist, Professor Lord Martin Rees, to find out about the Principia and the man behind it…

[In background]

Martin - So you're doing something on Newton and the Principia?

Izzie - Yes yes...

Martin - I’m Martin Rees, Astronomer Royal and Professor at Cambridge University.

Izzie - Now the Principia was first published in 1687. And it was essentially the foundations of classical mechanics. What exactly did it entail?

Martin - Well it was a wonderful mathematical achievement, and he used immense mathematical talents to codify lots of ideas about the laws of motion and gravity, and his book the Principia is famously in three parts. The first gives his famous laws of motion. The first is that everything continues in its state of rest or uniform motion, unless something pushes it, as it were. The second said that if something is acted on by a force then the amount by which it accelerates depends on that force and on its mass. And the third law said that if something pushes, there's a pushback, so what's called action and reaction are equal opposite. So those are the actual laws but what’s impressive is the way he use mathematics to apply those laws, particularly to the orbits of the moon and planets.

Izzie - Now those laws of motion may take you back to your high school physics lessons. But why are these so important?

Martin - Well, of course, until that time we didn't really understand. I mean, the laws of motion which were believed by most people since classical times were those of Aristotle, which were that everything stopped moving unless you stop pushing it. And that of course is true of most things. But nonetheless Newton realized that, in practice, if something is not moving in a steady way, something is pushing it, or something is dragging it

Izzie - and that something would be a force. So that's part one of the Principia covered. The second discusses how bodies move under gravity and resisting forces. And the third applies Newton's theories of gravity to detailed problems, like the motion of the moon and planets.

Martin - Well of course he was the first person to realize that the force that makes the apple fall and holds us on the ground, is the same as the force which holds the moon in its orbit around the Earth, and the earth in its orbit around the sun. And he was also the first to show in detail how these orbits worked. Of course it was known that the orbits were not perfect circles, that they were ovals or ellipses. He didn't understand why. And I suppose the most famous single achievement of Newton in the Principia was to show that if the force of gravity obeyed a so-called inverse square law, which means that it falls off by a factor of four if you go twice as far away, inverse square law, then that force will cause an orbiting body to move in an ellipse, where the source of the gravity has a focus. And so he actually showed that this inverse square law force explained why the orbits had the shape they do.

Izzie - Have you ever tried to read the Principia?

Martin - Well it's not an easy read, and in fact it's interesting that Newton didn't want it to be an easy read. We must accept that he was probably one of the greatest scientific intellects of all time, but he was a deeply unpleasant character really. He was solitary and reclusive, and in his later years he became really very vain and vindictive, and we perhaps should recognise him for his works, and not for his character.

Izzie - Yes, so definitely quite a controversial character. You mentioned he was a recluse. Do you think part of that is to do with the fear of someone might take these ideas from him?

Martin - Well he was deeply concerned about priority and that's why he had longtime disputes, but of course what was special about him was not only his brilliance, but his power of concentration. In fact someone asked him how did he succeed in solving these very difficult problems about gravity and inverse square law, and his reply was ‘by thinking on them continually’. He did night and day and there are all these anecdotes about how he forgot to eat his meals etc. and continued. This was particularly the case in the two years when he was writing his Principia. And of course remember it was written in Latin and there were later editions, and then there were English translations and French translations, and it became a book which was probably not understood by many people, but it became seen as an archetype for how we can actually understand and see patterns in the world. And this led to the idea of a sort of clockwork universe, which could in principle be understood by mathematical formulae.

Plane on Runway

29:49 - Propulsion: Prepare for takeoff!

This year marks the 100th anniversary of the Royal Air Force, how have planes evolved?

Propulsion: Prepare for takeoff!
with Justin Burrows, Rolls Royce

This year marks the 100th anniversary of the Royal Air Force. And, just last month, the newest fighter jet, the F-35 Lighting II, arrived in the UK. To celebrate these milestones, Chris Smith and Izzie Clarke embarked on the maiden flight on our own airline FlyNaked! Marika Ottman spoke with Justin Burrows from Rolls Royce in Derby about how we power a fighter - or indeed any - plane! But first, a special announcement from the crew...

Ladies and gentlemen, flight F-35 is now ready for boarding. Please make your way to gate 1 with passports at the ready.

Welcome onboard The Naked Scientists Airlines.Our in-flight entertainment will consist of a journey through time to learn about the evolution of the fighter plane. Today we will be flying on a Concorde. Although the Concorde is not a fighter plane, many of its features were inspired by military aircraft, including it’s supersonic shape and its powerful turbojet engine.In contrast, the role of a fighter plane is to take down enemy aircraft, usually in battles called dogfights. Fighters are designed to fly incredibly fast while also being highly maneuverable. Comfort is not a priority.

If you’ll indulge me ladies and gentlemen, the origin of fighter aircraft is quite interesting. In 1914, the first world war broke out. Airplanes at the time were made of wood and fabric. These wooden and fabric planes were completely unarmed. Their only purpose was to fly over enemy lines to track the troops and take photographs. It is said that enemy pilots would simply wave at each other as they flew past. However, as the war became more brutal, pilots became less civil and started carrying pistols on board. Some even threw bricks at each other! By 1915, machine guns were mounted to aircraft. And thus, the fighter was born.

Over the next 100 years, some remarkable advancements were made on fighters. We have gone from fabric and wooden wings to the F-35 lighting, but how did we get there? Stay tuned, and you’ll find out. Passengers, please fasten your seatbelts as we prepare for takeoff. Wishing you a pleasant flight here on the naked scientists.

Izzie - Sounds like a rather large engine, which makes me think: what does it take to power a fighter, or indeed any plane? To find out, Marika Ottman went to Rolls Royce in Derby. They built about a third of the world's jet engines and historically they've made engines like the iconic Merlin that powered the Spitfire. And they've still got examples of all of them. Justin Burrows is a material scientist with the company.

Justin - So were in the Rolls-Royce Heritage Centre. What this is is a chronological exhibition of technologies that the company's been involved with. We've got some piston engines here. so the Merlin. Then we move on to some of our early jet engines. And then we've got our latest large civil gas turbine engine, the Trent 1000.

Marika - The forward motion of an aircraft is caused by a force called thrust, which is produced by a propulsion system. In the early fighter planes of World War 1 and World War 2, thrust was produced by propellers.
Justin - Think of the blades on a propeller like two sides of a screw. So if you think about a screw that you screw into a wall at home, if you turn the screw it will pull itself into the wall. Well, a propeller kind of works in a similar way. So each of those blades as you spin them round, they then take the air and push it backwards.

Marika - propellers provide a simple and effective way to create thrust. So why don't we see propellers on modern fighters?

Justin - When we go into World War II, Spitfires were finding that if they went into a steep nosedive they’d get to, or approaching, the speed of sound. But what happens when you get there is that the air at that point is very very hard to move. The prop simply can't mechanically take the load on it so it's creating too much drag. It's also very difficult to have enough power to push the propeller through the air because it becomes very heavy. So it's kind of like trying to spin it through concrete at that point. So the solution to that was to go to jet engines.

Marika - In 1930 Frank Whittle submitted a patent for the turbojet engine. The development of the jet engine changed aviation entirely. Fighter jets were able to fly faster and higher, speeding past the enemy or around them in dogfights. Justin showed me one of the largest jet engines made to date, and took me through how it works.

Justin - We're looking at a Trent 1000 which is one of our largest civil aircraft engines, and we're standing in front of the fan section. Each one of the blades in here, just to give you an idea, is about six feet long and there's 80 of them in a conventional set in a jet engine. As these blades spin, they take air from the front of the engine and throw it towards the back. That is what gives us thrust on the aircraft. About 65 percent cent the air from that propeller bypasses the engine so it goes down the side of it. It just uses it to push the aircraft forward. about 30 to 35 percent goes through the center of the engine and that helps power the turbine section at the back of the engine. So the air that goes down the middle of the engine goes into the compressor section. So all that does is compress the air. It compresses it so well that it raises the temperature to about 700 degrees C, which is pretty hot to start with. With that point we then mix it with fuel which in this case is kerosene. We light a match, the temperature of the gas then increases dramatically and the pressure increases. So the turbine is very clever because it does two things, so it extracts energy from that gas which then drives the fan. The other thing it does is that gas going out the back also adds to the thrust.

Marika - Aircraft propulsion has advanced exponentially in the past 100 years. So what do we have to look forward to? Justin brought me to the technology centre to give me an exclusive peek into Rolls-Royce’s latest technologies.

Justin - So we are in the Technology Exhibition Building. This is purpose built for our end user customers. They'll come in here, see some of our new technologies, what we're going to be doing in the future. They also have the opportunity to look at the current build line as well, so they could see engines being made.

Marika - The current build line includes engines that are actually able to predict when they need maintenance.

Justin - As our aircraft are flying around they’re live, and they're sending data to what we call our operations center. We have a team of engineers looking at that data and if we've got an aircraft that is displaying a problem or an issue, we can arrange for a repair team to make the aircraft as soon as it lands with the parts are already there and they can fix the issue. And then there's no disruption to the customer. The other thing we can do is give the data to our manufacturing people and our design teams,they can then use that data from service of what happens to components to redesign components so they're more effective when they're in service. So there's kind of a whole feedback loop going on with all the data that we're getting from the aircraft.

Marika - So what is the future of jet engines?

Justin - One of the things we're involved with is an engine called UltraFan, which has two big improvements over the current civil gas turbines. One of them is it has a composite fan which is lightweight. The other thing is the fan is slightly larger. We've got a gearbox in that engine and that allows the fan to turn at a slower speed than the turbine. That enables us to deliver a product which gives fewer emissions and it's more effective than our current engine. We're looking at the potential for electric hybrid vehicles. What we then need to look at is materials for electric motors, energy storage how we can generate electricity to drive those motors, and how we can store enough power enough fuel if you like to keep the electric motor driving a propeller.

Marika - So just to be clear, you're talking about an electric airplane?

Justin - Yes we are. It won't be tomorrow but it might be a few days after that.

Plane Wing

37:33 - How do planes fly?

How do planes get off the ground, and stay in the air?

How do planes fly?
with Dave Ansell

It’s incredible that we can fly so high. In fact, how do planes get off the ground, and stay in the air? Chris Smith was joined by gadget whizz and Naked Scientists veteran Dave Ansell in the studio to tell us, or should we say, show us...

PA ANNOUNCEMENT - We’ll be cruising at an altitude of 60,000 ft and a speed of 1,000 mph. In a few moments time, we will be moving through the cabin to offer some refreshments.

Chris - Oh good. I am feeling rather thirsty. Right on cue.

Izzie -  I think some snacks have just arrived.

Chris - And a very beautiful stewardess

Stewardess - Champagne, sir? Caviar, madam?

Chris - Have you got anything better than that?

Stewardess -  No.

Chris - The thing about flying is that you have to actually know how your aeroplane works in the first place. It is amazing that aeroplanes even fly. You think of a fully laden A380, for example, there are 800 people plus on there. So we thought we would do an experiment to explain how flight actually works and how aeroplanes and wings work. So who better to ask than kitchen science veteran and actually whizz making science experiments to show how things actually work and that’s Dave Ansell. Welcome to the program Dave.

Dave - Hello!

Chris - What have you brought in?

Dave - I’ve got a lot of gadgetry here. I've got a big fan and model wings and things. Start off thinking about how planes fly is how you stay up in the first place. Everything is being pulled down by gravity and the fact you're not falling through the floor must mean there's a force pushing you upwards. And at the moment you're achieving that by applying a force downwards onto the chair and then Newton's laws mean that every action has an opposite reaction. The chair is pushing upwards with exactly the same force and holding you up so you don't fall to the center of the earth very quickly.

Chris - Right. So how does the wing of an aeroplane create that force, which then leads to the airplane being able to stay up in the air and combat gravity accelerating downwards?

Dave - So it must be pushing down on something and the only thing a plane has got to push down on is the air around it. And the part of the plane which holds it up is of course the wing. So I have a model wing here, which is made out of a bent piece of card, and we’re going to be wanting to see how the wing is affecting the air moving past it. Now to get any lift from a wing, you need the wing to be moving through the air. Now to see that while it's running around is very difficult so I’ve got a big fan which I can turn on and produce air flying past the wing.

Chris - Right. So we have a bent piece of card which is curved in the shape of a wing. You have a screwdriver with a ribbon on it, which is going to reveal where the air is going. So talk us through what will happen when we put the wing in front of this large fan. What should we be looking for?

Dave - In order to stay up, the wing should be pushing the air down, and we should to see that by the ribbon behind the screwdriver being pushed downwards.

Chris - Now I can understand how that will work with the bottom side of the wing because the wing is higher at the front than the back so air hitting the wing is going to be deflected downwards. So if you push the air downwards, it's going to push the wing upwards, as Newton's law tells us. What about the top of the wing though, does that contribute to the lift?

Dave - If you get the aerodynamics right, which is important part designing a plane, then air will tend to stick to a smoothly curving surface. So with any luck you will also get the top of the wing deflecting the air downwards and also producing lift.

Chris - So you get lift from the top of the wing and because you're pushing down with the bottom of the wing you get lift there too.

Dave - Exactly right.

Chris - Let's do the experiment then. This is noisy everyone at home so we apologize in advance. Here we go. So Dave’s turned on his large fan.

Dave - So at the moment I've just got the streamer ribbon moving in the air and it's is going horizontally. Now if I move the wing down towards it from the top you should see that that stream is being deflected downwards even though it's not actually touching the wing.

Chris - Yes, indeed. So the streamer is nowhere near the wing it's underneath the wing but the streamer is curving downwards just like the same shape as the wing. So there's obviously air being pushed downwards by the lower surface of the wing.

Dave - Exactly right. And similarly if we bring the wing upwards towards the ribbon from underneath the air starts to stick to the wing. So the air go over the top is also being deflected downwards and so pulling up the wing. So if I let go of the wing it moves upwards. It’s producing lift.

Chris - One last question for you Dave then. What about when a plane flies upside down when a stunt pilot goes upside down the plane still flies. How does he do it?

Dave - It's exactly the same principle. The plane is at an angle so the air hits the wing of the angle and you have to float you downwards so air pushes the plane upwards.

Chris - Are you saying the pilot basically has to modify his flying technique or her flying technique so the wing is still pushing downwards.

Dave - Basically the nose of the plane is pointing up a bit more if you're flying upside down than if you're flying horizontally because they're designed to fly right way up.

Chris - High angle of attack I think is the correct parlance, isn’t it?

Dave - It certainly helps.

British Airways Concorde

41:55 - Flight of the Concorde

Reporting from the fastest passenger plane that ever flew.

Flight of the Concorde
with Peter Halford, Imperial War Museum at Duxford

One particularly impressive aircraft is the Concorde, which is, in fact, the very plane we’ve boarded on our journey through the programme! Whilst it’s not a military aircraft, Concorde was underpinned and powered by military technology, and it flew faster than many modern fighters. To find out more about these magnificent machines and their capabilities, Chris Smith took a trip to the Imperial War Museum, at Duxford, to speak with aeroplane officianado Peter Halford; they met, literally sitting in the fastest passenger plane that ever flew.

Chris - So my seat belt is securely fastened and the seats aren't terribly comfortable, actually, for what would have been a very expensive ticket. But just please tell us who you are where we are.

Peter - I am Peter Halford, I’m formally the science and technology education officer at the Imperial War Museum, where we are today, sitting inside one of the first experimental Concorde supersonic aircraft. This particular one is very special because not only was it one of the test airplanes, it itself is the fastest airplane to carry passengers there has ever been.

Chris - When you say it's the fastest, as in this aeroplane has broken all the records.

Peter - This one has, yeah, and as things stand it will hold that record forever.

Chris - Now, what was actually involved in getting Concorde as fleet off the ground in the first place, how were planes like this one used?

Peter - This is a passenger airplane, but its history and its antecedents are from military aircraft, and military aircraft engines in particular were used in it. It's a combination of people wishing to fly faster, but also using the technology required in warfare.

Chris - How fast did this plane go?

Peter - Concordes are particularly well known because they’re supersonic, faster than the speed of sound, the speed of sound being somewhere around seven hundred sixty miles an hour. So this would fly faster than that, in fact twice as fast as that.

Chris - Let's talk about actually the aerodynamics of how this aircraft worked. What was special about it, why was it a game changer?

Peter - Well, firstly because it was using military engines, and also the development of the delta wings, so the beautiful shape of the airplane, because that is the most efficient way of having a wing for an airplane like this.

Chris - Indeed, the wings start halfway along the aircraft, and then they extend outwards towards the back, so they’re widest right at the back of the aircraft.

Peter - Yes. In contrast to conventional aircraft at the time, because of the speed. With the speed of sound, a tremendous pressure wave built up. In fact it's quite a sudden change from smooth air passing over an aerofoil wing, through to this shockwave which travels across the wing, and it changes the position of the pressure on the wing, making it very difficult to manoeuvre and control.

Chris - That's if you have a conventional wing. So is that what forced them to have to come up with this very clever design of this swept back delta wing, in order to surmount that problem?

Peter - Yeah, there are a number of solutions to this difficulty. When the pressure wave builds up, it builds up in a sort of cone shape around the airplane from the nose outwards. And if you can make the shape of the front edge of the wing more or less the same angle as the shape of the cone, then that pressure wave is not travelling across the wing, and not causing these difficulties that come with it.

Chris - If we won the clock back right to the early history of when people began to fly. Obviously, those early aircraft are very different than the one we're sitting in here. Talk us through how those early aircraft worked, and how they were engineered

Peter - all the aeroplanes fly in a similar way - lift has to be created over the aerofoil wing. But prior to that, people had attempted to make flying machines by flapping, having observed birds. However, for a human being to try and do what a bird does is impossible. People then, like George Kailey, where observing birds, and noticing that they could continue to fly without flapping their wings. So the aerofoil shape is a mimic of that.

Chris - We take it for granted now that the Royal Air Force has aeroplanes which have weapons mounted on them. But the early planes didn't have any weapons on them, they were really just for surveillance, weren't they?

Peter - Yes. Aircraft initially were for surveillance - a good way to observe the enemy was to get up to a high vantage point. However, with the observation aeroplane you need a nice steady platform so that you can look out of the cockpit and take photographs, sketches and notes and so on. So that's the attribute of observation aircraft that was very different from what we think of as a fighter aircraft now.

Chris - Moving time on a bit, when did people begin to develop things like the Spitfire?

Peter - After the first world war. There were lots of aeroplanes which then became redundant - people started to use them for racing, and those are particularly well remembered series of air races called the Schneider trophy, and three times an aircraft called the Super Marine S6 won that, and the Super Marine Spitfire was an almost direct development from that.

Chris - These are all propeller driven aircraft though, aren’t they. How did the invention of the jet engine change all this?

Peter - The jet engine was what you might call a step change. Suddenly everything was different. The gas turbine was the big breakthrough, and that happened during the Second World War simultaneously in Germany and in Britain, with someone called Vano Hane in Germany, and Frank Whittle in this country

Chris - And returning to the Concorde that we’re sitting in - when this was flying, and it's going at twice the speed of sound, what sort of drag was it experiencing? Because there must be enormous amounts of friction from all that air rushing past.

Peter - Yeah, air is a fluid lots of little molecules rubbing along the aeroplane, and as we know friction creates heat. So at the front of the aircraft it was probably 200 degrees and towards the back is probably getting on for 100 degrees.

Chris - It must have changed the length.

Peter - It certainly did, yeah, it lengthened by about 10 centimeters during its flight.

Plane landing on Runway

48:34 - Landing: The evolution of avionics

How do pilots know when they need to start descending, or where the airport is?

Landing: The evolution of avionics
with Terry Holloway, Cambridge Aero Club

How do pilots know when they need to start descending, or where the airport is? It turns out there is a whole host of electronics and instruments onboard planes that give pilots critical information. These instruments are especially impressive in the cockpits of fighter jets. Izzie Clarke spoke to Terry Holloway, Managing Director of the Cambridge Aero Club. What exactly are avionics?

Terry - Well avionics is a wide range of electronic and electrical equipment, which encompasses communication, navigation, a flight management system, an autopilot, in the case of military aircraft weapons systems management, and avionics are in satellites as well, global positioning systems accurately guide you to where you want to go to.

Izzie - Okay, so what instruments would you have found in the cockpit of a fighter plane from World War One?

Terry -  Very little, you would have had an altimeter which would have told you approximately how high you were. They weren't particularly accurate. And you would have had a compass which might have told you generally which direction you were going in, but for most World War One fighter pilots perhaps the Sun and its relative position to the time of day might have been more useful than that compass.

Izzie - So how did that all change after World War One?

Terry - Scientists and people involved with aeroplanes always tried to make advances in technology and none more so in trying to communicate with the ground, and to navigate, and get from A to B. The autopilot was a great invention. Strangely, the first autopilot was demonstrated in 1914 a very long time ago, actually before the Royal Air Force was formed.

These days if you're flying in an aeroplane the pilot doesn't really touch the controls at all. He'll do the takeoff. He'll generally speaking do the landing, although there is an auto landing system. Once the aeroplane is safely in the air, the autopilot will be engaged, at the autopilot will take you up to height. The flight management system will guide you through the airways and point you in the direction you need to go. And actually the pilot could completely go to sleep. The aeroplane would find its own way there, with very modern avionics and would even land itself.

Izzie - Hopefully they won’t be going to sleep!. If we fast forward to World War Two, how did cockpits change then?

Terry - They didn't really change very much. They had a few more instruments, blind flying instruments, so that pilots could find their way down and fly accurately in cloud. First World War; visual flying only, you need to see the ground. and if you couldn't see the ground you were in a great deal of trouble. So they had blind flying instruments, and the great aid was a radio because with the radio in the cockpit somebody on the ground could tell you where to go and radar had been invented. A chap called Robert Watson-Watt invented radar between 1915 and 1935, and that was able to guide fighter aircraft to hostile aircraft. And the next stage was having airborne interception radar installed in fighter aircraft, so when you get guided to within a mile or so of of the enemy your own radar can then guide you to it and you shoot it down.

Izzie - Now we're looking at the newest fighter jet, the F-35. How have modern day avionics progressed?

Terry - They are astonishingly accurate and amazing. For a start, the pilot is wearing a very high tech helmet, and his primary flight instruments, as well as the whole battle scene of a hostile aircraft, friendly aircraft, the assets around him are all projected on the inside of his visor of his helmet. He turns his head one way or the other, he gets a different view and the aircraft which are hostile, or not hostile, will appear on his visor where they are relative to him. The avionics are very complex and one of the big issues in the past of avionics in aircraft, is cooling. And if they weren't cooled sufficiently, they would be unreliable and they would fail. I remember flying in Lightning aircraft, the earlier English Electric Lightning aircraft, where the mean time between failure on the radar set was about 40 minutes which wasn't very good, and it was all to do with cooling and the thing heating up.

On modern combat aircraft, the avionics are absolutely reliable. They last forever, as they do on airliners and modern passenger jets. The other significant difference with modern air combat, is the support you’re provided by a number of other assets. There might be an airborne early warning aircraft which is maintaining the whole battle scene. You're being controlled by it, you’re communicating through it. You're able to find your own targets. Somebody on the ground might send you a message through a secure data link saying “here is the position of the target” you can identify it from your cockpit, you can then launch a particular missile, perhaps a laser guided bomb, or a missile against it and people in your headset will be watching exactly what you're doing, and the next step is almost asking permission, may I engage this particular target and a voice will say “yes you can” or “no you can’t.” conversely.

Izzie - Now there's obviously a lot of connection and communication there, and you said that there's this secure link that information is sent through. What if it isn’t, is there a risk that these F-35 fighters are too high-tech. Is there a risk of cyber attacks?

Terry - There is always a risk of cyber attack and the cyber attack will come in many different ways. It'll be attacking the ground stations, the radars, that are giving you vital information But it's measures and countermeasures. And if people are trying to undermine our capability, and cyber attack what we're doing, we're deploying measures to counter that. And there's a huge amount of research going on into into that whole area, most of which I hasten to add is very highly classified.

Audio book

55:01 - Brain response to Audiobooks

Does the brain respond differently between reading and listening?

Brain response to Audiobooks
with Matt Davis, Cambridge University

This week, Isabelle Cochrane asked Matt Davis from Cambridge University to read into this brainy question from Tuomo.

Tuomo - Does your brain respond differently when you're listening to an audiobook compared to when you're reading a book? And does this affect how much detail you can remember?

Isabelle - On the forum, Tomas reckons that the main difference is that in each case, there is activity in different areas of the brain. Evan, on the other hand, is more concerned about our safety:

Evan - If you are listening to an audiobook while driving your car, I hope there are at least some periods of time when your attention is focused entirely on the driving!

Isabelle - But what do the experts think? I spoke to Dr Matt Davis from the MRC Cognition and Brain Sciences Unit in Cambridge:

Matt - Reading and listening involve different senses. Each of these connects to a different part of the brain: things that you  see are processed in visual cortex, at the back of the brain, whereas things that you hear are processed by auditory cortex, which sits on the side of the brain, above the ears.  There are other parts of the brain that also make specific contributions to reading or listening, such as the parts of the brain that control movements of the eyes, or those that maintain attention when listening.

Isabelle - So, the simplest answer to the question is yes – your brain does respond differently in reading and listening, because sensory signals from the eyes and the ears make different portions of the brain ‘light up’.

Matt - But, when it comes down to processing the meaning of written and spoken sentences, we see that many of the same parts of the brain are involved, regardless of where the information comes from. The same brain systems seem to be involved in accessing the meaning of written and spoken words. But understanding what you read requires more than just knowing the words. Comprehending a story requires you to build a mental model of what is going on. Your mental model for the story that you’re reading or listening to is critical for being able to remember it - otherwise, the story would be a series of disconnected sentences that will not linger in your memory.

Isabelle - So, is there any reason to think that listening to an audiobook or reading a book might be better for remembering the story?

Matt - Assuming that comprehension is equivalent in reading and listening, we might expect retention to be similar. However, when a story is difficult to follow – think Dostoyevsky rather than Dan Brown – having the opportunity to re-visit tricky sections could be helpful. In this respect, reading might offer some advantages over listening – readers can easily move their eyes back up the page to re-read text that they misunderstood first time around. At the same time, anyone who finds reading difficult – young children or individuals with dyslexia – might retain more from listening to an audiobook. The additional effort involved in reading the words uses mental resources that they would otherwise need for comprehension and memory.

Isabelle - So there you go. If you have trouble remembering this explanation, then reading the transcript of our show might help! Thanks again to Dr Matt Davis for that. Next week, we’re figuring out our footprint, with this question from Charlie:

Charlie -  ‘What is the minimum area required to sustain one human being in terms of oxygen and food?’


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