Flying into the Future

Will flights get faster? Could electric planes exist? And can our own Naked Scientist land a plane?
30 July 2019
Presented by Izzie Clarke, Adam Murphy
Production by Matthew Hall, Izzie Clarke.


Plane flying through light clouds


This week, The Naked Scientists are taking off into the future of aviation: will flights get faster? Could we see a fully electric plane? And can a Naked Scientist land a commercial aircraft? Izzie Clarke and Adam Murphy find out… Plus, in the news, a new way of disguising cancer drugs as fat, sharks are in danger, and how do you make a bad joke funnier?

In this episode

Headline about cancer

00:53 - New cancer treatment disguises drugs in fat

Every two minutes someone in the UK is diagnosed with cancer, can a new treatment change that?

New cancer treatment disguises drugs in fat
with Nathan Gianneschi, Northwestern University

Every two minutes someone in the UK is diagnosed with cancer. And there are a range of options when it comes to treatment. Frequently, though, chemotherapy drugs, designed to hit fast-growing cells like cancers are used. But not all rapidly-growing cells are cancerous, so there are inevitably side effects. Now, scientists at Northwestern University have found that dressing up chemotherapy drugs as fat molecules makes it much easier to concentrate their actions on cancer cells alone. Izzie Clarke heard how it works from Nathan Gianneschi.

Nathan - We're hoping to disguise cancer medicine as fat molecules, as nutrients. There are proteins, for example, that circulate within your blood that will transport long chain fatty acids around the blood, and then there are receptors on cells of all types that are hungry to consume these proteins and the fat that they carry. Tumour cells are very very interested in this as a nutrient source. They're dividing and they're growing and they're wanting to consume fat and energy and so we connect drugs to one half of this modified fat and then allow the other half of the fat to engage the body's transport systems, so you sort of hitchhike on the tumour's systems for acquiring and consuming energy.

Izzie - This really is a Trojan Horse cancer treatment?

Nathan - Right. And it really is one of the goals; how you can get to the point where normal tissues are, let’s say, less damaged. The idea is to make the patient less sick by getting more of the drug to the tumour.

Izzie - And what is this drug that you're using and how does it get into that fatty molecule?

Nathan - The drug, what we would call the warhead, the active part that goes and kills the cell is called Paclitaxel. In the clinic today it's used in two main formulations. We took that same drug and the carrier, the rocket for that warhead is this fat chain; 18 carbons in a chain with what we call a carboxylic acid at the end. And so it's a chemical bond between the drug and that fat chain and the preservation of that carboxylate is what tricks the body.

Izzie - And how well did it work in tests?

Nathan - It works very very well. We used animal models for bone, colon, and pancreatic cancer. These are animal models of human tumours and the human tumours will grow in the mouse. We're able to treat with our drug versus the clinically approved drugs and show that we increase the survival of the animals as well as decreasing the size of the tumours. But just because you did that in the mouse, of course, doesn't mean that it's going to work in a person. If it does work then you have an advantage over current medicines and you can get approval and help people.

Izzie - Why is this better than current methods?

Nathan - In the study, we did a head-to-head or, in other words, a direct comparison with two of the FDA approved formulations for these types of drugs, and the fact is that we have much higher doses so we can go to higher doses because we can target better than the currently approved drugs. And so by being able to target to the tumour better that means you can inject much more drug and that means you can more quickly kill the tumour. At the maximum doses, what we call maximum tolerated doses, we had better efficacy than the clinically approved drugs because of that targeting ability. The next step is to see if we can actually translate that to a human outcome of course.

Great White Shark

04:29 - DANGER: Sharks at risk in this area

A global study of sharks finds that they’re in danger of being fished over a quarter of their entire habitat.

DANGER: Sharks at risk in this area
with David Sims, Marine Biological Association Laboratory

A global study of sharks has found that they’re in danger of being fished over a quarter of their entire habitat. This comes from an international collaboration of marine biologists, who have tracked ocean sharks to produce the first ever world map of their hotspots. By comparing the hotspots to fishing routes, they have shown that the most valuable species are in danger over almost three-quarters of their entire range. Phil Sansom spoke to David Sims, one of the study’s authors, who is a senior research fellow at the Marine Biological Association Laboratory in Plymouth.

David -  Pelagic means "of the open ocean," and so pelagic sharks are sharks which roam the open ocean. By using satellite tracking to identify shark hotspots across the global ocean and also tracking longline fishing vessels, we found that the overlap of the shark hotspots where they prefer to be and hangout, overlaps at least 24% of the time with these longline fishing vessels.

Phil - So that's like a quarter of the entire area that sharks live in is an area that they’re in danger of being fished?
David - We couldn't track every shark, but for the just under 2000 sharks that we did track yeah, 24% of the places they prefer to gather and to be, were entirely overlapped by longline fishing vessels. And these longline fishing vessels, each of those vessels deploys a line that's a hundred kilometres long with over a thousand baited hooks.

Phil - So that's a serious deal for sharks, right?

David - It is, yeah. Obviously, they're attracted to the baits on these lines, and because the lines are so long and there are thousands of these vessels across the global oceans which are trying to catch sharks, because, as opposed to 20 odd years ago sharks have a real value now.

Phil - Now let me ask you; it can't be easy to figure out where sharks gather or where they like to live, how did you actually do it?

David - A project at a global scale requires a global scale research group. There's 150 scientists across 100 institutes in 26 countries. We tagged just over 1800 different pelagic sharks and we gathered all the satellite tracking data of all sorts of different species of pelagic sharks. We gathered it all together in a giant database and then we were able to analyse, to explore, the movements of the sharks in relation to the environment.

And what we found was that the sharks prefer to be in areas where there are strong boundaries between different water masses with different characteristics, so fronts between different temperature water masses for example. And these sort of transition areas, these sort of boundaries are areas where there's usually lots of plankton and, of course, that plankton attracts in fish and squid that the sharks like to feed on.

Phil - That's so interesting that you actually had to physically tag the sharks.

David - That's it. That's the nature of this project is that it's the first one that's really worked at the global scale for pelagic sharks. We tracked about 23 different species, including the Great White shark and three species of hammerheads actually, but also the Blue shark and Shortfin Mako shark, and they're interesting because those two species make up about 90% of the pelagic sharks which are caught by high seas and shell fisheries. So those two are the most commercially important and obviously they're the ones that we are particularly concerned about as a consequence of this study, because we found that, in fact, 76% of blue shark space use and 26% of shortfin mako shark space use was entirely overlapped by these longline fishing boats.

Phil - Now let me ask you because you keep saying "overlap," but how do you know that overlap necessarily means they're in trouble?

David - Yeah, it's a really good question. We actually thought about that and in the study we actually calculated the fishing effort that was going on and related that fishing effort to actual landings, so these are tons of sharks that have been recorded on the global databases. And what we found was a positive relationship between the amount of fishing effort and the magnitude of landings of those species, so there was a direct link between the fishing effort, the overlap, and mortality.

Phil - So what do we do?

David - What we propose is that the maps we’ve produced of where the hotspots are can really start to become the foundational blueprint of shark conservation at the global scale. And so where we have these shark hotspots it could be that these are the sites that policymakers and scientists may select to protect sharks. That's not to say that that's the only tool that can come from this sort of study.

One thing that this does suggest is that the surveillance of megafauna like sharks is actually a very powerful way in which you can start to look at a new management of the oceans. If you know where the sharks are and maybe other megafauna like turtles and whales, it might be possible then to focus where the enforcement happens and for focusing where particular patrol vessels might be, for example. So I think the future holds this much more broad and satellite-based technology led conservation, which I think for sharks will be absolutely crucial.

Cigarette butt on the ground

10:12 - Cigarette butts harm plant life

In the first study of its kind, the plastic in cigarette ends are stunting the growth of plants around us.

Cigarette butts harm plant life
with Danielle Green, Anglia Ruskin University

In this hot weather, many of us will be flocking to parks and gardens. All too often though you’ll likely come across cigarette butts lying on the grass. And apart from being unsightly, a study from Anglia Ruskin University suggests that these butts can harm local plant life. Danielle Green sprinkled pot plants with cigarette butts and measured the impact they had on how her plants grew. So what did she find? Emma Hildyard caught up with her at the local park to find out...

Danielle - There's one, there's one. Actually, there's a cluster of three yeah, and they are the most common litter item that's found on cleanups and stuff like that, accounting for 30% of litter in some places.

Emma - so we need to get rid of them?

Danielle - Yeah, we need to bin them - bin the butt.

Emma - What made you interested in this study?

Danielle - Walking around the parks and all these beautiful green spaces around Cambridge that we have and just seeing cigarette butts everywhere, and I started to think; “I wonder if this is having an effect on the plants”. It's quite a simple pot experiment where we had either grass seeds or clover seeds, and we had a piece of wood as a control. We had menthol versus regular, we had smoked versus unsmoked to see if it was the plastic in the filter that was having an effect as well. Most cigarette filters are made out of a bio-based plastic called cellulose acetate which is derived from plants essentially. They don't biodegrade very quickly; some studies say two years, some say more than ten. Furthermore, cigarette butts are made up of thousands of tiny little microfibres which are a type of micro plastic essentially, so even when they do break down there's a possibility that they're still persisting as micro plastics.

Emma - So every time we throw a cigarette butt onto the grass we are effectively throwing plastic into the ground and into the ecosystem of the plants?

Danielle - Yeah, exactly. When you’ve smoked a cigarette you're also containing all those toxins from the cigarette into it as well, so there's thousands of different types of chemicals and toxins that have been shown to have effects on different plants and animals, on their own. Nicotine would be the most obvious one. They use cigarette butts in some countries to prevent malaria so they might put them in water bodies to try to kill the larvae of the mosquitoes, for example. So there are some uses for them as well, but it's obviously not what you want.

Emma - In your study you've tested unsmoked cigarettes, smoked cigarettes so just the filter is left, and you've left some tobacco in some of them, so it's half smoked, so what did you see?

Danielle - I expected to see that the ones with the tobacco would have a stronger effect, but overall, even the unsmoked filters had really similar effects to those that were smoked. In some cases there were stronger effects of the smoked cigarettes but overall, the plastic itself is decreasing plant germination and growth, and the root biomass of clover was reduced by around half.

Emma - So the roots are the bit of the plant that take in the nutrients in the water from the soil, so if the root mass is smaller does that mean they get less food and water?

Danielle - Yeah. Similar effects have been found in response to drought, for example. So plant roots might shrink and in this case, first of all they’re not stable, and secondly they're not able to absorb as much water and nutrients as well.

Emma - So they won’t grow as well, they won't grow as fast?

Danielle - Yeah, exactly. There has been another study done in aquatic ecosystems. They also discovered that even the unsmoked butts had an impact on fish, so freshwater and marine fish and could actually lead to mortality. They found a stronger effect of the smoked ones.

Emma - What would you say to people that smoke and throw their cigarettes all over the floor?

Danielle - I'd say it's just as bad as littering any other sort of plastic, and please don't. This study has actually gotten attention worldwide, and there have been quite a few anti-littering campaigners that have been tweeting it and sharing it on their social media. So hopefully there's going to be some action coming from this to either create more bins, raise awareness that they are plastic. Do whatever we have to do to reduce it. There are some studies that are actually recycling cigarette butts and using them as some sort of building materials and stuff like that. So if we can reuse them that would be even better.

Computer generated image of Red blood cells travelling in a blood vessel

14:25 - Gene therapy for haemophilia

People with haemophilia cannot clot their blood. An new gene therapy could change that...

Gene therapy for haemophilia
with Sandy Macrae, Sangamo therapeutics

People with haemophilia don’t produce enough of a critical factor that helps blood to clot. As a result, they have to inject themselves regularly with a replacement form of the factor to avoid suffering lethal bleeds into their joints and organs. But, within a year or two, it should be possible to offer patients with haemophilia a long-term solution using a gene therapy technique that enables cells in the liver to produce the missing blood clotting factor. Sandy Macrae is the CEO of the US-based company Sangamo therapeutics that’s developing and conducting clinical trials on the new technique. Speaking with him at the recent Biotechnology Innovation Organisation (BIO) meeting in Philadelphia, Chris Smith asked Sandy about the therapies the company are exploring...

Sandy - So I think the one that people talk about most is for haemophilia, which is the blood disorder that the Royal Family suffered from in Victorian times. And now there are two or three companies, including mine, that have medicines that will be on the market in the next 3 to 4 years and provide an option for these patients that they won't have to take factor every day or two, but will have one injection and be done for 5 to 10 years.

Chris - Are you saying then that you've got a way of genetically modifying a haemophiliac so they can make the thing they don't have?

Sandy - We need to be careful how we describe that. In gene therapy you park a version of the gene in the cell. So it's not stitched in, and it's not forever, and it may only last 5 to 10 years. But for these patients, 5 to 10 years is a long time compared to having to inject yourself every day.

Chris - What's the strategy then? What do you actually do to get that gene into them and where do you park it?

Sandy - That's a good question. We borrow a virus and the virus goes to the liver where it infects the liver cells. Once it infects the liver cells it releases the bit of DNA that then produces the factor that the patient was missing, and the liver acts like a factory releasing a little amount of factor each day.

Chris - What's the virus that you use to get the gene into the liver cells?

Sandy - It's called an adeno-associated virus, so it's related somewhat to the cold virus.

Chris - And how does the liver tolerate that? Is it quite comfortable to have this virus going in there?

Sandy - Mostly. Most patients tolerate it very well. Occasionally, patients will get a slight inflammation of their liver and that's something that we need to monitor carefully, and so for the first 3 to 6 months of the patient's treatment they'll be having their liver enzymes measured on a weekly basis. Very few have had any trouble with this course of treatment.

Chris - And how much virus do you actually have to administer to the person in order to treat them? Because you've got to presumably hit a lot of cells in order to get them making enough of the factor, and that means you're going to need a lot of virus?

Sandy - You need to hit a sufficient number of cells to produce the protein. You give a very large number of virus particles: E to the 11, E to the 12, E to the 13. These are more than grains of sand on the beach.

Chris -  That’s a hundred billion plus, isn't it?

Sandy - Yes. It's a huge amount.

Chris - Can you make that much easily in the lab? Because that's been one of the problems that’s held back this field in the past is actually scaling up the amount of virus you need to do it in a way that's going to be deliverable for the numbers of patients that we need to treat.

Sandy - Absolutely right. One of the most important things in this field is having reliable manufacturing. It's possible to do this, you make large vats of virus - a bit like homebrew - and you create virus in the billions, as you describe. It needs to be done with quality because patient safety is the most important thing.

Chris - The liver cells aren't long-lived like a nerve cell though are they? They turnover, they die off, and they’re replaced. So that means, presumably, you're going to have to keep doing this to keep the levels topped up in the person?

Sandy - Our liver replaces about 1/7 of its cells every year, so over the course of 10 years you'll be replacing a lot of the cells. Gene therapy doesn't pass it on to the daughter cells, to the next generation. We need to follow these patients out for a period of time to see how long it lasts, what's the durability. But if I was a patient, if I could get 5 to 10 years of benefit from it, I think that's a good balance of benefit and risk.

Chris - So where are you in the trials process now with this?

Sandy - We're in the proof of concept trial. We've seen some really powerful results from our virus and our construct, and then we're at the stage of handing it over to our partner Pfizer, who'll take it into phase three and then to registration.

Chris - One problem that people who have to inject factor VIII for haemophilia experience from time to time is, because they're putting into their body something that their body doesn't naturally make, the immune system regards it as hostile and you get an immune response against it. And that means that actually they then don't get any therapeutic benefit through injecting it. Is there a risk - because you're putting in something that some of these haemophiliacs aren't naturally making with your virus - you're going to have the same problem?

Sandy - A great question. And there's a cohort of patients with antibodies to the factor that mean that they would be excluded from the current trials, and there's other medicines that other companies are developing for them. Nobody has yet seen that reaction from patients with gene therapy, and it's perhaps because it's given chronically in low levels and perhaps something to do with the liver that we can avoid that. But of course we need to follow these patients long-term to make sure they get continued benefit from it.

Chris - How do you actually get the virus just into the liver?

Sandy - We infuse it into a vein. It's a very unremarkable process where the patient waits for an hour or two while the drip slowly drops the virus into the vein and it manages to find its way there.

Green comedy chattering teeth

20:10 - Knock, Knock? Canned laughter helps bad jokes

Some jokes are terrible but is there a way to make them seem funnier? Neuroscientists at UCL have the answer

Knock, Knock? Canned laughter helps bad jokes
with Sophie Scott, University College London

What’s orange and sounds like a parrot? A carrot! Some jokes are truly terrible. But is there a way to make them seem funnier? Neuroscientists at UCL tried to see if terrible “dad” jokes could be made funnier by adding laughter to them. They played jokes with and without laughter to groups of autistic and neurotypical adults to see how they responded. A key difference between the two groups is in how they mentalise - that is “think about other people thinking”, says Sophie Scott, author of this might you expect a difference in how people respond to laughter, as well? Ankita Anirban spoke to Sophie to find out more.

Sophie - What we did was we took a bunch of jokes and we deliberately set out to find, like, a really bad group of jokes because we wanted it to be possible for them to be funnier, and then we add laughter onto the jokes. And what we did is we used laughter that was either being produced by someone who's absolutely helplessly laughing or we have those same people laughing but we've told them to laugh so there laughing to demand, and that laughter is less intense. And then we gave them back to people and we asked people to rate the jokes again and now all they are doing is listening to the joke but now there's also laughter. And what we find is adding in any laugh makes the jokes seem funnier and then the more intense the laughter the funnier it makes the joke. So what we’re actually seeing is people are processing the laughter implicitly and it's influencing what they actually think of the joke.

Ankita - So is this why TV and radio use these laughter tracks in comedies to make people laugh more?

Sophie - The original introduction of laughter tracks, which was for comedy on the radio, that was done because people at home didn't necessarily realise they were listening to something that's supposed to be funny. So they started using a live audience frequently. And, of course, laughter normally happens in a group with other people so it's a strong cue to people that this is comedy. What these data suggest is that this is not only telling you it's okay to laugh, it's also giving you a sense that the whole thing is just funnier.

Ankita - So who did you ask these jokes to?

Sophie - We asked them to two groups of people, so we either had neurotypical participants and we also had a group of adults with autism, and what we found, actually, was that the results were pretty much the same for both groups. So both the neuro typical and the autistic adults have the same influence of laughter, so the more intense the laughter is the funnier it is making the joke. The only difference that we found is that the autistic adults rated all the jokes as funnier so they are possibly being a bit more generous to the jokes than our neuro typical population were.

The only thing that is worth bearing in mind, and Sarah White a collaborator on this paper, she's pointed out that first of all our autistic adults are - they're high functioning -  so we might be seeing an element of compensation here. And she's also found when you look at autistic adults performing mentalising tasks, which is classically something that children with autism can really struggle with, what she finds is that frequently they pass those tests, they perform "normally" on those tests. But what she's found is if you scan those autistic adults they are producing the same behaviour but using different brain regions than the neuro typical population, so we might still be looking at compensation that’s resting on different neurobiology.

So that's the next step for us; we're going to take this in the scanner and see if we can unpick whether or not the behaviour and the neurobiology of laughter is the same in the two groups, or if the behaviour is the same but the neurobiological basis still might be different.

Ankita - So do we know much about the neurobiological basis of laughter at the moment?

Sophie -  What we have found is that you certainly get a lot of facial mirror activation when you're listening to laughter which you might expect from a behavioural contagion. It's not confined to laughter, you also get it for positive emotions like cheering but those are also still social emotions. You also get lots of activation associated with people trying to work out what the laughter means. You also get lots of auditory activation, particularly for spontaneous laughter, probably because you hear sounds you don't hear in any other context. So, actually, we can get a lot of different neural systems activated by laughter and it will be interesting to see which, of any, or all of these are involved when the laughter's influencing how funny a joke sounds.

Ankita - What's the worst joke that you heard during the study?

Sophie - I think the worst is “what day is the best day for cooking? Fryday!!”

Ankita - Well maybe if you add some canned laughter to that it will make your audience laugh.

Sophie - Well, empirically, I hate to suggest, might be correct. It needs it, certainly.

An inside view of the controls in a plane's cockpit

26:25 - Can a novice land a passenger plane?

Naked Scientist Matthew Hall is put to the test of landing a commercial aircraft... simulator!

Can a novice land a passenger plane?
with Ben Bowness, Virtual Aviation in Cambridge

Which would you prefer: a plane flown by humans or one that is fully controlled by autonomous systems? Currently, aircrafts are controlled manually by a pilot but can also switch over to autopilot, an automatic system. In some cases, pilots can be in full control of the airplane for as little as 10 minutes throughout an entire flight. To find out exactly how safe this level of automation is for autopilot, and whether it could replace humans altogether, Matthew Hall set out to Cambridge Airport...

Matthew - Autopilot in commercial aircraft has come to the point where it's been implemented in almost all aspects of flight - all except the takeoff process. It's a little scary to think about just how much of our safety, while airborne, is in the hands of an automated software. We do also have the pilots that can take control at any time, in case of an emergency, but what if something were to happen to those pilots? Are we at a point now, in automation, where a novice could grab control of the plane and potentially land without incident? In a mission to discover more about present and future autopilot systems, I took off toward Virtual Aviation Airline Training which is home to a flight simulator used to train pilots for commercial aeroplanes...

Ben - Today, you're going to be seeing an airliner simulator - it's the Airbus A320 simulator and it's a device that is used to train pilots and it simulates the flight deck of an Airbus A320.

Matthew - That's Ben Boness, an aeroplane pilot and flight simulator instructor who is going to coach me through the landing process in his flight simulator.

Ben - The simulators are as close to the real aircraft as you can get. We use official system that simulates the outside environment, but all of the switches and the controls within the simulator are exactly the same in terms of look and feel as per the real aircraft. So the autopilot has to replicate what the autopilot would do on the real aircraft for us to have the aircraft or the simulator certified for what we use it for, so it is a hundred percent exactly the same as per the real aircraft. The only difference with the simulator, of course, is that there isn't motion. It's a fixed base simulator but apart from that everything is exactly the same as the real aircraft.

Matthew - But it's a simulation. What are some of the controls that you can do with this simulator that you can't do in real flight?

Ben - We have the ability to freeze a simulator. So if we want to cover some points of learning we can just freeze it and then talk about the particular manoeuvre, or what we’re looking at in the simulator - so we can freeze time. We are able to simulate different conditions, we can introduce failures, so that the trainees can see how the aircraft reacts. And we can change the position of the aircraft as well, so we could one minute be making an approach into a particular airfield, and then 10 minutes later we could reposition it to another airfield to look at a takeoff.

Matthew - If something were to go wrong and the pilots were unable to fly this plane and one of the customers at the back had come in and fly this thing, had to land it, is the autopilot in a condition where a novice, like myself, could take control and land a commercial sized aircraft?

Ben - I'm confident that we can talk you through how the autopilot flies and the different modes we can use to operate it and we'll see if you can land the aircraft yourself. I'm confident you'll be able to.

Matthew - Well no pressure then!

Ben then took me through an open hangar full of planes housing the simulator entrance. He opened the doors, and I was immediately in awe at the sight from the other side. The simulator itself is a massive metal box, easily the size of a living room, and on the inside metal box half of the interior was just dull white walls but the other half was alive - with the lights and controls of a perfect 'copy and paste' replica of a cockpit from a commercial aircraft.

Ben shut the soundproof doors, turned on the simulator, sat me down in the captain's chair and programmed the scene for an in-flight emergency situation. The pilots are down; I've been thrown into the front, I’m at 35,000 feet and I have no idea if I can land this thing.

Ben - So you need to come forward.

Matthew - The first step: activate the autopilot which is turned on simply by pressing a button labelled AP1.

The second step: descend to 20,000 feet which is controlled by turning a dial anticlockwise until the number 20,000 is displayed on the screen. And just like that, the plane cuts its throttle, and starts descending with no further control from me where it will eventually level off on its own.

The third step: once cleared by air traffic control is to get to 1300 feet in preparation for landing.

Ben - Okay. So we've now descended from 35,000 feet and we find ourselves 3 miles from the runway, 1,000 feet above the ground, currently flying at 140 knots and now it's Matt's job to get us on the ground.

Air France's Concorde plane

31:39 - The faster planes of the future

Could we see the return of supersonic flight? Mechanical engineer Michael Carley explains all...

The faster planes of the future
with Michael Carley, University of Bath

It's no secret that Izzie Clarke isn't the biggest fan of flying. So for her, the faster the plane, the better. She can reach her destination quickly and - hopefully - won’t have to spend as much time on the plane. Could we see faster planes in the future? Could supersonic flight, travelling faster than soun, be a commercial option? Michael Carley is a senior lecturer from the department of Mechanical Engineering at The University of Bath and joined Izzie in the studio to explain supersonic flight.

Michael - Supersonic flight is flight faster than the speed of sound, so faster than 770 miles an hour, if you're at or near sea level. Typical altitudes for commercial aircraft, you’d be doing more than about 670 miles an hour.

Izzie - Wow! What could it do for us? What is its potential?

Michael - Really, the point is that it's very fast, so for people who feel a need to not spend much time in the air and want to get to wherever they’re going in a hurry and who can afford to spend the money to make that worthwhile, that is the advantage. The issue for a lot of us would be that the amount of money you would need to spend to travel that fast just isn't worth it.

Izzie - Right, I see. And we saw something like this in the past, which was Concorde, so what was that and what went wrong there?

Michael - Concorde was a joint Anglo-French high-speed aircraft, so it flew at about twice the speed of sound. Technologically it was a massive success. It advanced the technology in all sorts of ways. It did successfully fly across the Atlantic at twice the speed of sound. The thing that used to impress people was that fighter pilots would occasionally meet a Concorde, the fighter pilot would be sitting in a cockpit at the same sort of height but having to wear a special pressure suit. People on Concorde were having a nice meal, sitting in their shirtsleeves in an air-conditioned cabin.

So it had comfort, it had speed, it had everything except it wasn't economical. It cost about $12,000 in modern terms to fly from New York to Heathrow and back again, which is about three times the price of modern first-class flight. It was very very noisy which made it completely unacceptable to people living on the ground and in the end it just wasn't possible to sell enough of them to make it economical to run.

Izzie - Now, economics aside, how are planes like this able to fly so fast?

Michael - Partly utterly monstrous engines and that is one of the things you need. You need to generate a lot of thrust to overcome the drag that's involved in flying at these speeds. You need a specially shaped wing, so Concorde is one of the very few utterly recognisable aircraft. People who have no interest in aeroplanes can recognise Concorde. So it's delta wing, it's got a very sweptback leading-edge; that is essentially what allows it to fly at those speeds.

There are a couple of other issues, the control is difficult. Matthew, I'm sure, will be able to tell you how hard it was to land an aeroplane. The problem with something like Concorde was that you had to keep the nose so high you can't see over it when you're landing or taking off, because of the difficulties of landing and taking off at low speed, which you have to do with those monstrous engines. So there are particular difficulties that go with high-speed aircraft that aren't, therefore, pretty conventional, economical, normal airliners that are in service today.

Izzie - And where are we now though with these superfast planes?  Could we see something like this make a return?

Michael - We could. There are a few options depending on who you are. One of the things to notice is that even the military don't have supersonic transport aircraft. Supersonic aircraft in military use are purely for combat. There have been proposals in the past to convert essentially fighters into small supersonic transports for business purposes. There is one company which has just placed a firm order for 20 supersonic business jets, so they'll carry about 10 passengers.

So realistically, we might see business jets or supersonic aircraft for business use in the near future, next 5 to 10 years, it's unlikely that we'll see commercial aircraft being operated by the airlines.

Izzie - And what are some of the issues that they would have to overcome regardless of whether this is business or commercial?

Michael - The big one is going to be fuel cost, they burn a lot of fuel. One of the things that we need to deal with is flying less. Supersonic aircraft, there won't be very many of them, but they are disproportionately high consumers of fuel so that will become an issue depending on how regulation goes in future.

Nobody has solved the noise problem yet, although NASA seemed to be getting close to it. In the next year or two they should have a demonstrator flying which will reduce noise to acceptable levels. What they say is it will be like a car door being closed rather than a massive bang if one of these aircraft goes over.

So there are the two big ones, solving the issues that allow you to operate the aircraft. Most of the other problems have been solved in a technological sense on Concorde, but we still haven't solved the problem of what it costs to run them and how we get the noise down.

Izzie - So do you think we will ever see something like a commercial supersonic plane in the future?

Michael - It's not likely. We’ve worked out how to fly reasonably economically with fairly conventional aircraft. If we are going to spend that kind of money again, I suspect some people are going to go for bust and just use suborbital flight. So in effect you use a small spacecraft, and then instead of thinking about three or four hours between London and New York, you're talking about one hour from London to Sydney, and in effect you bring space technology down to Earth rather than trying to bring military fighter technology to the flying public.

Image of a plane wing flying above clouds

38:13 - Can commercial flights go electric?

Fully electric cars are everywhere now, why is there still no Tesla equivalent for aeroplanes?

Can commercial flights go electric?
with Paul Robertson, University of Cambridge

We’ve been talking about the future of aviation, and that future might be electric given that batteries are overall a cleaner energy source than fuel. Fully electric cars are everywhere now and batteries are constantly improving their capacity by about 5% each year. But that being said, why is there still no Tesla equivalent for aeroplanes? To find out, Izzie spoke with Paul Robertson, a senior lecturer in electrical engineering from Cambridge University.

Paul - There are some leisure aircraft, which are just one or two seaters, which are purely electric but they're very much limited by their range and flight time. So typically up to about an hour’s flight time would be what's currently achieved in these sorts of aircraft. It's a 'hot' research topic at the moment, looking at moving up to larger aircraft from your two seater, four seater, nine seaters up to airlines sort of scale

But one of the major issues which limits electric aircraft is the power density in the batteries. By that I mean for a given weight of battery, how much energy can you store compared to burning fuel using a conventional engine? And at the current time, equivalent weight-for-weight batteries or fuel, then burning fuel gives you about 20 times the energy that you'll get from batteries.

Izzie - Wow. And what about the mechanics going on, say, with a car compared to a plane, does that impact anything at all?

Paul - In cars, when weight is an important issue in cars, for performance and to a lesser extent for range, but in an aircraft it's absolutely critical because the total weight of the aircraft determines how much power you need to fly and so if you're storing a certain amount of energy that tells you how far or how long you can fly for. By increasing the weight of batteries, for example, in an aircraft, you make the overall aircraft heavier, it therefore requires more power. So if you just double the number of batteries, the weight of batteries, that does not double your range because you’ve paid a penalty for the extra weight that you're carrying.

Izzie - If we were in a situation where we could get rid of all of the fuel, with the batteries we've got at the moment, how far could a plane go?

Paul - If you're to take out of say an airliner, you took the engines off, you take the fuel tanks out and you replace that equivalent mass, that weight with batteries and electric motors, if you could do that your flight time would probably be around half-an-hour.

Izzie - That's not very much at all!

Paul - So it is rather limited. However, there are some applications where even short flights of that sort of endurance are useful. City to city hopping is a possibility. We still though have the issue, how do we recharge the batteries or do we swap them out, what do we do in order to refuel the aircraft? Because the infrastructure to do that is very different to what we currently have which is just piping liquid fuels around. So it isn't just the technology of the batteries in the aircraft themselves, in any sort of commercial application we have to think about the infrastructure which goes around it.

Izzie - And what are some of the other major issues associated with say an all electric commercial aircraft?

Paul - Okay. So we've talked about the batteries which is the main one. There are lots of other things which concern us if we're going to commercial aviation. We need to look at legislation and certification, so that's what makes the aircraft safe, how do we prove it safe, and how do we operate it. If we change the propulsion system from our normal aviation fuel to electric then, as I say we need the ground infrastructure, we need all the testing and qualification work to be done. We need to rewrite the manuals on how the pilots are trained for these propulsion systems, we need change to simulators.

So there's a lot behind commercial aviation and, in fact, the regulations are really only just beginning to be looked at now for how do you certify these sorts of aircraft?  It's not so much in issue at the very small-scale, leisure aircraft, there are experimental categories we can work in there. But when you move to passenger carrying the general public, then it's a very different regime and everything needs to change basically as we move from our current fuel burning approach to a purely electric approach.

Izzie - Could we see a combination of fuel and batteries? Is that something that would be possible?

Paul - Yes that is. That's what we call a hybrid electric propulsion system. What we're doing in that case is we are assisting the conventional fuel burning engine, whether it be a turbine or a piston type of engine, we're assisting that with an electrical boost, or we’re combining an electrical machine with that fuel burning engine so that we can improve the overall efficiency of the system.

Izzie - And  so would it be that you'd have the batteries to get off the ground but you'd then use fuel for once you reach your correct altitude?

Paul - Yes, that's the basic idea. Burning fuel, because of the large amount of energy it stores in a given mass, then that's a good way to propel yourself a very large distance. But the addition of an electric boost means that you can optimise the size of that fuel burning engine for that long cruise condition and the extra power you need for takeoff and climb is provided by the electrical system.

Izzie - And what about going fully electric, could that be a possibility?

Paul - It's a possibility, but I think it's quite a long way off. The density of the energy storage in batteries is not high enough at the moment and it'll probably be some decades before we can store enough energy to take an aircraft to match the sort of ranges which we can get now. So going transatlantic, transcontinental, it would be very difficult for a purely electric aircraft to do that for some time yet.

An inside view of the controls in a plane's cockpit

44:18 - Results: Can a novice land a passenger plane?

We find out if Naked Scientist Matthew Hall can land a flight simulator...

Results: Can a novice land a passenger plane?
with Ben Boness, Virtual Aviation in Cambridge

It’s time to check back in with Naked Scientists Matthew Hall and Ben Boness from Virtual Aviation to see if Matt can land a plane. Last we heard, they were a thousand feet above the ground preparing for their landing in a flight simulator, with Ben coaching Matt through the descent. Let’s find out their fate…

Ben - So they tell you to push this one here. That is the autothrottle and here we have the thrust lever, so if you just move them forward... Okay.

Matthew - The autothrottle maintains the speed of the aircraft by adjusting the thrust of the plane and keeping it at the correct altitude before descending.

Ben - We also need to slow down. The aircraft has what we call an autobrake, so as we touch down the brakes will automatically engage and slow down the aircraft. So if you just select this button here...

Matthew - I set the brake to medium with the push of a button and we were almost at the runway. There was just one more button to press.

Ben - That's our approach button, and that's telling the aircraft to follow an instrument landing system to touch down.

Matthew - Landing was imminent. The last piece of the plane puzzle was to pull a giant lever back, cutting all the thrust, as soon as air control instructed me. And we were almost there.

Ben - Here we go…

That's good, so we can see the aircraft touches down, keeps us nicely on the centreline and you can see our speed reducing now. Welcome to London Stansted.

Matthew - Wow, we're alive.

And all it took were three buttons and a lever. Do not be fooled by the simplicity though because it has taken over a century of development for the autopilot software to get this good at its job.

With all the passengers safely on the ground, I sat down with Ben to ask him about the future development of autopilot systems.

Ben - A lot of the advancements lately have been in communications, so how we communicate with air traffic control on the ground, so a lot of that is becoming text messages between the aircraft and the ground controllers. But from an autopilot point of view they are extremely accurate, they are extremely reliable and you can see today how they can best be employed to help us as pilots.

Matthew - Absolutely! On the note of that though, is there a fear in the industry that this software will get so developed, so keen on landing/takeoff/flying that we’ll see a future of a pilotless cockpit?

Ben - I think anything like that is certainly a long way off. I don't think we're going to see, certainly manufacturers testing pilotless flights for at least the next 30, 40, maybe 50 years.

A Rolls-Royce Trent900 Jet Engine

47:14 - Cleaning up plane pollution for the future

How do we reduce the emissions released from planes every year?

Cleaning up plane pollution for the future
with Hector Pollitt, Cambridge Econometrics

While electric propulsion remains in development, liquid fuel reigns supreme which is not good news for air pollution emissions. A 747 burns on average 5 gallons of fuel per mile! Multiply that by several hundred miles a flight and then by several million flights a year, the emission toll adds up quickly. To find out how much of an impact this has on the environment and if there is a solution Adam Murphy and Izzie Clarke spoke with Hector Pollitt, director and head of modelling at Cambridge Econometrics.

Hector - We look up into the sky and we see aeroplanes with vapour trails and we think oh, this must be causing a lot of pollution. To some extent this is true; however, at the moment the aviation sector accounts only for 2% of global emissions. The concern is that whereas most of the other sectors in the economy are starting to decrease emissions, in aviation we're very much seeing the opposite going on, and it's predicted that in the coming decades overall emissions from aviation could triple.

Adam - So where is this increase coming from? Why are we seeing it going up?

Hector - Yeah in summary we're seeing more flights overall, more aeroplanes taking off and landing, so more fuel being burnt and more emissions resulting. In the UK, there's this constant debate about the expansion of Heathrow in the southeast; and the airport capacity, of course, that is another way of enabling more flights. Even more important than that is the growing size of the middle-class in the developing world and all of these people with their newfound wealth who want to go to other countries, other continents, and see other parts of the world for themselves.

Adam - Now we heard about the issues and challenges behind electric flight, but are there any other solutions being tested or implemented right now that can help?

Hector - Yeah. And I think when it comes to climate change we're always looking to technology for the solutions. We heard about electrification as one possibility in aeroplanes. There are also potential biofuel options that are out there in the future. Again these are still under development and we don't know how that will go, but they may be something that's a bit more realistic in the shorter term. Also there are some specific short run measures that would improve efficiency in aeroplanes. One option would be even getting the airlines to use the latest flight planes available to improve efficiency. Also reducing taxiing on runways, for example - planes could be pulled up rather than operating under their own thrust in the airports. And a more rational flight path through the air traffic control services, and that could reduce overall distance per flight which would help a bit. But these are only short run solutions.

Adam - You mentioned biofuel, what exactly is that and what state is that in?

Hector - It's an area where there is a lot of research going into at the moment. It hits some of the same issues that we heard with the electrification about the power-to-weight ratio in the planes. I suspect at some point we will start to see a blended fuel coming in, a bit like we have in petrol in our cars, so you'll start to see an increasing proportion of jet fuel kerosene being mixed with biofuels. It's still at a reasonably early stage though, we can't say anything for sure on this topic.

Izzie - What actually would they be mixing in with kerosene?

Hector - Yeah, that's a good question and I suppose it really depends on how the technology will go. We hear quite a lot about algae-based research and next-generation biofuels, so it's something that's a bit different to the corn that's grown and converted into biodiesel that we put in our cars at the moment.

Adam - What's the future here? Do we see an end to this problem?

Hector - It's going to be very difficult to stop people from flying I think, particularly in the developing world. I think when it comes to climate change though, the state we’re at now, and not least we're seeing the record temperatures last week, I think we really need to throw everything that we can at the problem, so I would propose a multi-pronged approach. Yes, let's try to reduce our own flying a bit. Putting a tax on aviation fuel which is currently pretty much tax-free at the moment would certainly help with that. Consider airport capacity, whether it’s really necessary going forward. Let's use the most efficient planes that are available. Let's put in these other efficiency measures as well and do the best that we can with that. Let's see where we can go with these new technologies as well - just throw research resources into it and maybe something will pay off in the long run.

Sunrise or sunset over sea

51:53 - QotW: Sunrise, sunset? How to tell in a painting

Listener Manik wanted to know how you can tell whether a painting is of a sunset or a sunrise...

QotW: Sunrise, sunset? How to tell in a painting

Ankita Anirban has helped us paint the picture of an answer to this question from Manik. It was over to painter and creator of the series Dinotopia, James Gurney, and physicist William Livingston to shed light on the situation...

Ankita - First we put it to the forum, and got your suggestions. Evan_au suggests looking at the time stamp on your photo - which I think is cheating! ChiralSPO recommends looking for known landmarks, but that methods relies on you already knowing something about the landscape. We turned to James Gurney, painter and creator of the series Dinotopia, to ask him for his thoughts on this.

James - There's nothing fundamentally different about the light effects at sunset or sunrise, and there's no way to tell which you're looking at from the light and colour effects alone. The cause of those light effects are the same. Sunlight travels through more atmosphere as the rays approach the horizontal. Passing through more air scatters out more blue wavelengths from the light rays, making the light that remains appear increasingly orange or red. Of course, this effect happens both at sunrise and at sunset when colours are at their richest.

A single photo or a painting may be able to tell you about the altitude, the cardinal direction of the Sun, and about the height and distribution of cloud layers. And some art historians have argued that paintings of sunsets after the eruption of Krakatoa in 1883 reveal colours that were more pronounced worldwide. But it can't tell you whether it's morning or evening.

Ankita - If there are differences between sunrise and sunset, they're qualitative and subjective. In some environments, humidity and dust may be stirred up at the end of the day because of evaporation and turbulence, and these effects can increase the saturation of the colours. But you wouldn't be able to guess that from a single image.

James - Emotional subjectivity also plays a part in our human perception of sunsets and sunrises as we experience them in time. While a sunset builds gradually to a dramatic crescendo before quickly transitioning to twilight, a sunrise starts off with a blast of colour and, as Wordsworth says, the "vision splendid" fades "into the light of common day".  

Ankita - What about the Moon? Can you tell whether it’s moonrise or moonset from a picture? William Livingston, from the National Solar Observatory in the USA, wrote in to tell us this:

“In the case of the Moon, every society has a favourite imagined figure marking the full Moon. In the Orient and Europe it is a hare. To North Americans, it is “the Lady in the Moon”. At Moonrise, she is seen in profile, looking downward. At Moonset, her gaze is upward”.

Next week, we’ll be answering a question from Saugatt...

Saugatt - Hi, Chris, this is Saugatt from Nepal, and my question is - because of the monsoon, the death toll raised to around 150 in India, Nepal, Pakistan and Bangladesh. What is the exact cause of monsoon rain, and how will it be affected because of global warming?"


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