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A BMX park in the sky
Episode 827th July 2023 • CAA on General Aviation • UK Civil Aviation Authority
00:00:00 00:26:42

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We speak with Dave Boxall, Chief Airworthiness Engineer at Cameron Balloons on their recent adventure with Red Bull on the Don’t Look Down project.

You'll hear how this project came to be and the amazing adventure these organisations went on to get the balloon into the air.

Kriss Kyle, Scottish BMX Pro said:

“I’ve had to push past my fears several times before on Red Bull projects, but nothing has compared to this. Riding my BMX at 2,000ft, you’re so high up it almost doesn’t feel real anymore. I trusted the crew with my life, and wouldn’t have been able to do it without the help of Cameron Balloons, who worked in partnership with the CAA to help make BMX riding at 2,000ft a reality.”   

Cameron Balloons is the world leader in the manufacture of lighter-than-air aircraft and fabric structures. Their mission is to deliver the highest quality aircraft-standard engineering through robust and innovative products; led by a creative team, supported by a reliable aftersales service.

Established in 1971, they have built over 9500 hot air balloons and continue to support this diverse industry with in-depth and realistic expertise.

About the 'Don't look down' project:

Don't Look Down: Kriss Kyle BMX film (

Kriss Kyle's Don't Look Down: how it was made (

BMX Pro Kriss Kyle Interview - Don't Look Down film (


Voiceover 0:10

Welcome to the General Aviation podcast from the UK Civil Aviation Authority

Alex Blomley 0:22

Hello, and welcome to a special GA podcast edition. Today we're at Cotswold Airport, where we're joined by Dave Boxall, Chief Airworthiness Engineer at Cameron Balloons. And John Davies from our very own GA Airworthiness team. Cameron balloons recently worked with Red Bull on the 'Don't look down' project the world's first floating skate park at over two thousand feet in the sky. Their challenge was to suspend a one of a kind carbon BMX bowl weighing 2.5 tonnes from a hot air balloon, taking on a number of technical challenges along the way. Dave, how are you today? Thank you for joining us.

Dave Boxall (Cameron Balloons) 0:55

Hi, it's great to be here.

Alex Blomley 0:56

So, Dave, what happened? How did this come about? Did Red Bull approach you? Did they sort of turn up one day and say hello, can you help us?

Dave Boxall (Cameron Balloons) 1:05

The original contact came through our sales team. And so I was in the office and one of our sales team came upstairs and said, we've had this enquiry from Red Bull, they've got this mad idea to suspend a skate bowl from underneath a balloon. Do you think we can do it? And of course, I said yes.

Alex Blomley 1:22

What else could you possibly say? But joking aside, it sounds quite a monumental task to try and create a balloon in order to fulfil their requirements in this case.

Dave Boxall (Cameron Balloons) 1:33

It is quite a big task. And of course, with these projects, you don't know what they're going to be like until you get into them get into the detail, which is why it's always important to say yes, straight away.

Alex Blomley 1:43

So we mentioned that the BMX bowl was 2.5 tonnes. What were your key considerations then when it came to designing and manufacturing the hot air balloon that was going to essentially carry this into the air?

Dave Boxall (Cameron Balloons) 1:57

So the first thing we had to do was just to establish the scope of the project, the weight of the bowl, how many people we'd need in the balloon, and that would allow us to size up the balloon and with a two and a half tonne bowl, and our team to film and operate and all the rest of it, we ended up with a huge balloon, it's over six hundred thousand cubic feet. So that's six times the size of a normal sport balloon and half as big again, as the the largest balloon that's currently being operated in the UK. From there, we have to figure out what the bowl is going to be made of how that's going to work, what it's going to weigh, how we're going to suspend it from the balloon, and then more crucially, even than, all of that, how we're going to operate it because we're got to get into the air, get it down again, and make sure that it's safe for people on the ground, as well as everyone involved with the project.

Alex Blomley 2:42

So you talk about, you know, the different people involved. So of course, we mustn't forget that the point of having the BMX bowl in the air was to allow Scottish BMX legend Chris Kyle, to perform his BMX routine. So I guess that's quite a unnerving element to this particular challenge as well.

Dave Boxall (Cameron Balloons) 3:01

Well, it's certainly not like anything else we've ever done before. You know, so we had Chris in the bowl. And his tricks are just amazing. I hadn't realised quite how far out of the bowl he'd be going. I think remember, when we were just talking about about it early on, I said to Chris said, Do you ever fall out of the bowl? And? And he's like, no, no, hardly ever? And he said, but I won't be riding the rails on this one. Which is why when I saw the film, I had a sharp intake of breath when I saw that trick where he bounces off the guardrail.

Alex Blomley 3:34

Yeah, it's sort of that slight panic isn't there? Because I know you mentioned about people and logistics and I suppose ensuring the safety of both Chris and and obviously the crew in the basket and people on the ground. And all of that had to go into understanding, I suppose what you would create in order to make all of this happen?

Dave Boxall (Cameron Balloons) 3:49

Yes. So there was a lot of work. So between us and Red Bull, there was also a bowl design company who actually came up with the shape that concept of of Chris's bowl, and then we had to figure out how best to keep him in it. So there was a rail even though Chris decided to ride it, and we had to make all kinds of mitigations. And from Chris's point of view, one of the key ones was that we made Chris wear a parachute with an automatic opening device. And that meant that if the worst happened and he did come out of the bowl, then the parachute would open automatically. He'd make a nice soft landing and he wouldn't endanger anyone on the ground.

Alex Blomley 4:25

Lots to consider and just going back to the size and scale of the balloon so you said that it was about six times the size of a normal sports size hot air balloon 30% larger than the largest balloon being operated in the UK. So this is what the first time a hot air balloon of this size and scale has been operated in the UK before.

Dave Boxall (Cameron Balloons) 4:42

I think it is. Certainly a balloon of this size has never been routinely operated in the UK. So you know that was quite a challenge. It's a massive balloon with the bowl on the bottom. You know, that's just another big complexity and to get the bowl, the balloon manoeuvre with bowl to sit to connect all the rigging to make a nice, safe takeoff. That requires some really, really good weather. And, you know, one of the other bigger unknowns of the project was what the landing would be like. Because again, landing a balloon with a big weight suspended under it. That's pretty unusual as well.

Alex Blomley 5:15

So when you're in your office as it were sitting down at your desk, scratching your head as to how this is going to happen, I suppose you do you model this? Do you kind of scale this out to kind of help put into theory, some of those questions over how the landing and the takeoff will work?

Dave Boxall (Cameron Balloons) 5:30

Yeah, we do. We do. Like a bit of brainstorming around the office, we have everything 3d modelled, so we can take a look at what we think is going to look like. And then we recruited early on a test pilot Pete Dolby, who's a very experienced balloon pilot, he's done quite a lot of flying with big passenger balloons. So he's got the right kind of background and experience. And we sat down with him over, you know, a few cups of coffee going, how's this going to work? What are we going to do? How do you think it will happen, and just trying to scheme out how to make the landing happen, how to make the takeoff happen, what we thought we could really, really get away with, but also to get his buy in on it. Because you know, as the captain of the aircraft, he's got to be happy with what we're doing.

Alex Blomley 6:10

And you mentioned, obviously, you're working with the Red Bull team. Obviously, they're the ones that came to you in the in the first instance, a real collaborative effort, I guess, between yourselves, the carbon manufacturer, I think you said that was Red Bull Racing, and yourselves. How did that all work then in practice?

Dave Boxall (Cameron Balloons) 6:26

Well, it's all happened at the tail end of the pandemic. So I think we started under the lockdown rules. And everyone had had had a lot of time sitting at home trying to dream up mad ideas. So Red Bull came to us, we had a meeting and they actually came to the factory and everyone was masked up, and we're all being shown around the factory. And then we had lots of zoom meetings where we kind of schemed up ideas. And early on the plan was for quite a simple bowl, you know, a simple rectangular bowl with swept corners, but somewhere along the line, Red Bull decided that was under ambitious. And they came up with a kind of a more complex bowl shape, kind of kidney shaped bowl that that was flown under the balloon. And of course, all the time, we've been worried about weight, because the bigger the balloon, the harder it is to operate. And so we'd been driving to push the weight down. And that was when they came with a more complex bowl, that's sort of the trade off was, we had to go with a lightweight bowl. So a fancy construction. And that's when the Red Bull team got Red Bull Racing involved. So they are pretty good with carbon fibre. And they were able to design and manufacture a lightweight composite bowl.

Alex Blomley 7:31

Amazing. So I feel like I must join John Davies into the conversation now. So John, you're obviously a CAA, airworthiness regulator for GA. What was your first first response, I suppose when Dave got in touch with you about this?

John Davies 7:46

Well, Cameron balloons hold the same sort of level of organisation approvals as people like Airbus, its regulated in very much the same way. So we didn't really have any concerns as we'd expect the organisation to put forward a test plan, flight conditions and everything that we need to make the activity safe.

Alex Blomley 8:05

And were you worried at all I mean, uh, you've mentioned obviously, that they have various permits in place. But were there particular things that you were concerned about, I suppose that needed to be taken into consideration with something like this?

John Davies 8:17

Well, as you're all aware that one of our roles is as the aviation safety regulator, and our most important part of that is ensuring that third parties, people on the ground, like maybe people working at airports, like Kemble, or just innocent bystanders are protected. So we went through with Cameron, all the different possible risk scenarios, and made them ensure that all the risks were mitigated, and that any new features or novel features were properly assessed.

Alex Blomley 8:44

So Dave, how did you find working with the CAA on this sort of project?

Dave Boxall (Cameron Balloons) 8:47

So I mean, we've worked with the CAA. We've been manufacturing balloons for 50 years, obviously, I haven't been doing it quite that long. But we have a good relationship with the CAA, you know, it's based on years of experience and trust and respect for each other's position. And so early on in the in the project, I got in touch with our normal points of contact within the CAA. And I said, Look, we've had this inquiry, how are we going to manage it? You know, do we need a CAA permit? Can we do it under our design organisation flight conditions, and you know, immediately I got a positive response, which was very much, yeah, we can work that, I'm sure we can do it. We just had to figure out how. And what we ended up with, is we ended up doing it under our design, organisation approval under our own flight conditions, but with an enhanced oversight. So actually, it was pretty handy to be able to run through all our mitigations to have a good think about things, and then send it to someone who was standing outside the project, and them have a look and come back and say, you know, this is all good. But did you think of this? What about that? Oh, just one other thing? Yeah.

Alex Blomley 9:52

All very positive it seems, I suppose actually, there is that. As you said, it's quite nice to have different perspectives to be able to kind of oversee and make sure everything's kind of running as you'd as you'd hope it would do. Okay, so we're here at the Cotswolds airport as this was one of the first sites chosen to be a test site for the balloon. So what considerations did you think about when you were choosing the best sort of place to try and see if all of the theory would run in practice?

ve Boxall (Cameron Balloons):

So we had a lot of thoughts about where we could fly from, but we had a bunch of key criteria. I mean, firstly, it has to be a closed site, because you know, you wouldn't want to try and do this kind of thing in a public park, you know, we have to be able to control the access so people can't, you know, wander up and endanger themselves or the people involved in the operation cazzola headquarters quite centrally positioned within within southern UK. And it's got good access to the motorway, which means that the team are spread out all over southern UK, Red Bull are based in Milton Keynes, the operations company are based in South Wales. So we all had to come together somewhere. And so that was quite important. We didn't want to be launching it from Devon where everyone would have to travel a long way. But also Kemble gives us a good a good flying area, there's not too much airspace nearby, we have to sort of watch out for Brize and Fairford, big open areas around it, which means that we've got somewhere to put the balloon down at the end of the flight. And so that was what drove us here.

Alex Blomley:

So from a logistical point of view, I mean, I guess the actual BMX bowl itself, and getting the balloon here itself, we're talking about quite large pieces of kit. And I guess that was a challenge in its own right.

ve Boxall (Cameron Balloons):

So balloons are very portable. They're all designed to pack down into trailers and to be unloaded and sort of set up before flight. So the balloons quite simple. But the bowl weighs two and a half tonnes. It's enormous. I can't quite remember the actual dimensions of it, but it's big and it's transported in lots of pieces on the back of a lorry, it takes maybe a day to put it together, you know a little bit less but to take it apart. So moving the bowl around is quite a thing to do. So the bowl has to be able to erected in the days running up to the launch and be secure on site. And of course the bowl's yet another bit of the equation to consider. When we land a balloon in a farmer's field will always have to get it out. A balloon, you can manhandle if you have to, a balloon this size would have been quite tricky. But to get the bowl out, we had to have mechanical lifting. So we had to be able to get in a lorry with a lift on a crane on it. And all that kind of thing. So it makes the project very complex.

Alex Blomley:

And John, when it comes to test sites and things like that, from the CAA's perspective, what are we mindful of when it comes to testing? I mean, were you present at those testing sessions?

John Davies:

Yeah, we came to the first test. So our role in this is to ensure that the organisation are following their own procedures, and also to take a general sort of safety sense check of what's going on. So we interviewed some of the engineers involved, we interviewed the ground crew to make sure they've been properly briefed, of course, we interviewed the pilot to ensure that he had a good understanding of what the ask was and what the scope of his task, and to ensure that he had a full understanding of the risks involved and the operational flight envelope.

Alex Blomley:

So our role really, is to just sort of make sure that everybody who says they know what they're doing knows what they're doing, we wouldn't necessarily be the ones to say that something couldn't go ahead, we'd kind of leave the operations to make that decision for itself.

John Davies:

In most test flying scenarios, the pilot of the aircraft, the captain is responsible for making all the difficult decisions, and we fully support any decisions that they make. But it is good for us as part of our general oversight of the organisation to understand the safety culture, and also that they put in place the right scale of operation to support which is a very complex task.

Alex Blomley:

So I guess an operation of this size and scale, I mean, weather is obviously important. With a balloon this size, I think balloons are probably always very weather dependent. But I mean, with a balloon of this size and scale, your weather limitations, have always got to be always be perfect. I just thought I suppose they are factors that you're also thinking about when you're attempting to do something like this.

ve Boxall (Cameron Balloons):

So always with balloons weather's a huge issue the balloons a big sail, so we can't cope with a lot of wind. And for this flight, we had to have really good weather conditions. It has to be nice and clear both for VFR conditions and to get good film of the project. Because we've got to blow this big balloon up, then we've got to move it around, we've got to tow it over the bowl, drop it into the bowl, hook up all the connections and lift the bowl. So we've got a load of wires dangling for the balloon that need to be connected and then lifted out and pick up this big weight. It leaves us with this quite long period where this balloon is lightly loaded quite floppy and quite vulnerable to wind. So perfect conditions are really important.

Alex Blomley:

So did all the testing go to plan then with those specifications that you've mentioned?

ve Boxall (Cameron Balloons):

So our first outing we'd looked at the weather or maybe a week ahead, we'd kept reviewing it. And when the day came, it was windier than forecast. We had the bowl team here and then we got the bowl out. We got the balloon out. And by the time we'd got some air into the balloon it was pretty clear, that we weren't going to fly. But we thought we'd put the balloon up, see what we could manage, you know, within safe limits. But in fact, we had to abandon that test before we'd even got the balloon completely inflated. So after we've cleared up, packed everything away, we were actually all sitting here in the The Av8 restaurant at Kemble. And somebody came up with the idea that, really, we had a lot to learn without flying the balloon just about trying to connect all this together to find out what it was like when Chris was riding in the bowl. And someone had the idea that if we could do it indoors, it would be great. And there's only one place where we could go indoors and that's the Cardington hangar. So by the end of the week, we were really lucky Cardington's really busy. It's used a lot for filming work, but there was a spot available. By the end of the week, we had a date to go in and take the balloon out inside Cardington hangar. And that was fantastic. We were able to inflate the balloon with no time constraints, we were able to just practice that bit of manoeuvring the balloon over the bowl, dropping it in making the connections, just really finding out if everything was working right. And then we were able to lift the bowl up, Chris was able to ride it. You know, we could get the balloon only a couple of metres off the ground before the top of the balloon was pushing against the roof of Cardington. But it was enough that Chris could ride it, we could see that it was all going to work. If we could get the bowl off the ground, it was going to be fine. Chris could get an idea that the bowl was rideable, because nobody really knew how it would behave with Chris riding it. And it's a strange thing. You know, the bowl bounces under the balloon, the balloons rocking and swaying just a little bit, the baskets bouncing, what it's like for Chris to ride, you know, I have no idea. Because, well, I'd have no idea how he rides that anyway. But with the bowl moving underneath him. And so all those questions got answered in a single test session. And our plan had been to make a progressive series of flights to lift the bowl up, maybe hop it across the airfield to make sure we could land it, try and get a little bit of Chris riding perhaps. And this answered all those questions. And we felt able to go from that indoor session to a position where we'd go straight to a flight.

Alex Blomley:

Okay, so it's definitely that sort of progression of learning, I suppose, as well with something like this having not necessarily taken on the challenge of the size and scale before that was important for the team as you went along.

ve Boxall (Cameron Balloons):

Yeah, I think that's right, you know, always test flying. It's always about progressive learning always that we part of our test plan is always for review between fights to see what we've learned. And so, so yeah, the indoor session was what actually turned out to be to be one of the key moments. And we were back on standby for another couple of months for a flight at Kemble. But that didn't happen. We never got the weather for it. And so we postponed it through last summer. So sort of Autumn Winter of this year. Well this last winter, and at that time, we decided to move the launch site to Charlton Park airfield, which is just down the road from here, which is just a little bit lower, has a little bit more tree shelter, and we thought would give us a better chance of making a launch.

Alex Blomley:

So Cardington hangar, I mean, quite special that you're able to build everything inside and see how the testing session went. So what made you pick that particular location? Was it just size and scale?

ve Boxall (Cameron Balloons):

Yes, so Cardington hangars, there are two hangars there. And they were built as part of the Great British airship programme, in the '30s. So the R one hundred, the r one hundred and one were, well one of them was built there, and one of them was operated out of there. So they had just an enormous indoor space. I think the Cardington airship hangar is over 50 metres internal height, the length of it is just enormous. And so when we tested the balloon, the balloon was tucked into one corner.

Alex Blomley:

So in terms of testing a balloon, how does it actually work in practice? I mean, do you have to go up to the full feet that you're planning on flying it? Or can you do it differently?

ve Boxall (Cameron Balloons):

Well, one of the things about a balloon is that it's quite unique amongst aircraft because we don't really have much airflow, the balloon floats in the air, almost like a rough floats in the river. So we don't have any aerodynamic effects. There's not many dynamic effects at all. So it does allow us to do a lot of testing of regular balloons on the ground, you can see a lot a lot of what you know without leaving the ground at all, or by lifting the balloon up just a few feet. And this was what was great about Cardington that we could assemble the balloon, we could do our sort of launch prep, we can actually pick the balloon up just a couple of metres, and we could find out nearly everything we needed to know about the flight. I think the one thing that it didn't clear was what the balloon would be like to land. You know, we could touch it down, but we had no speed then. So the big unknown after Cardington was what it would be like to land in a wind.

Alex Blomley:

Yes, that's true because I suppose you've got the perfect theory of what you'd like to have happen. And I suppose this happens with hot air balloon flying anyway. But then you've got that extra complexity of having such a large unit, let's say hanging underneath the basket as you're coming in.

ve Boxall (Cameron Balloons):

Yeah, that's absolutely true. I mean, lots of people like to tease us that you know that landing a balloon is really a controlled crash. And we try to steer clear of that misconception. I think we never quite knew how would it would work out landing the bowl. And so one of our fears was that it would be a controlled crash. And so we were always discussing that, you know, if it all started to go wrong, the thing would be to get the balloon on the ground, get the balloon deflated, as fast as possible, have everyone in the basket in their safe positions. And really important to note that Chris was in the basket for the launch and the landing, we weren't carrying Chris in the bowl for the launch and landing, we lowered him up and down on a winch. And so the idea would be if it was a windy landing, with everyone tucked down in the basket, holding on tightly, everyone's wearing helmets and harnesses, so they couldn't fall out. And then it would be getting the bowl to touchdown as gently as we could, then deflating the balloon as fast as we can, while everyone held on and waited for it all to stop.

Alex Blomley:

So in terms of your relationship, then with the CAA, with all of these various different testing sessions and different things that you were finding out along the way, how did you kind of work with the CAA on those sorts of things.

ve Boxall (Cameron Balloons):

So throughout the project, we were regularly in contact with the airworthiness team, and operations as well. So we were always keeping them informed about what we were doing, they came out to the initial test here at Kemble, and to the Cardington test, we fed back from those every time we had the balloon out, we let them know beforehand to see. So they were able to turn up if they wanted to. And after every flight, we had a debrief to let them know how it had gone.

Alex Blomley:

So from your perspective, John, I suppose that open dialogue is something I suppose you'd stress with any manufacturer that we're working with or an organisation such as Cameron Balloons for projects that they may be working on.

John Davies:

Yeah, in the GA sector, it's always helpful to work collaboratively rather than acting like a hands off regulator from afar. In this case, every time that with the communications between us and the organisation that gave us more confidence in allowing them to continue with it. And once the basic challenges of taking off or landing, the balloon had been assessed and addressed, we were more or less happy for them to continue on their own.

Alex Blomley:

So really, John, I suppose what we're kind of showing through this project is we're actually very keen and supportive of different things that the GA sector may be doing, I suppose it's just us being able to kind of be just one of the stakeholders part of that to kind of be a supportive player, I suppose ultimately.

John Davies:

Well, one of our roles, as well as being the safety regulator is to promote growth within the industry sectors. And the way that we do that is working with all the manufacturers, not just Cameron balloons, with all the novel projects they've got, we've got another UK manufacturer just started up making hot air balloons. So the manufacturing sector in the UK is buoyant, as they would say.

Alex Blomley:

So once you've had your testing phases, and periods and you feel comfortable, that everything's in there, you're going to get a plan, who then makes that final decision on not just weather, but making sure all the team is in place to obviously make the challenge happen, but obviously record it and video it and have it available for us to see later.

ve Boxall (Cameron Balloons):

So that's a really good point, because it's an enormous exercise, getting this balloon out because its not just about the balloon. There's the balloon, there's the bowl, there's Chris's team, we had two helicopters filming, there were multiple drone teams, because we had an FPV first person view drone being operated out of the basket, we had cameras in the basket and the drone. So an enormous group of people. But the way it worked was that the the sort of key project principles were having a call once a week throughout the standby period. So Pete Dolby, who was our pilot, he would check the weather before that he was watching the weather all through the standby. And he'd make a prognostication and make a guess for the or a forecast for the following week, and whether he thought there was going to be an opportunity. And then if he saw an opportunity, everyone would be put on standby for that, and the wheels would be would be set in motion, you know that everyone would start planning around it, and the helicopters would be booked and, and all the people lined up. And then as we got closer and closer, we call the standby, we'd then be on a sort of a daily review of the weather as we got closer and closer. And we did have multiple occasions where we'd call a slot from a week out. And you know, and three days out, we'd say no, because that's about as late as you can reasonably cancel it by the time we get the day before you might as well all turn up because everything's booked. So we were really lucky. I think we cancelled one flight a couple of days out. We had two really successful flights. But there must have been close to 100 people at the launch between all the various components of the team.

Alex Blomley:

I think your point about helicopters and drones and it's a real collaborative GA sector achievement, isn't it really. It's so great to kind of be able now to watch back this amazing feat that Chris pulled off in his floating BMX SkyPark bowl. But without all of those players working together, it wouldn't have really been achieved.

ve Boxall (Cameron Balloons):

I think that's absolutely right. And you know, I have to say, I'm really glad that I only had to be responsible for the actual balloon part of the operation. And you know, the guys at Red Bulls projects. They made an enormous effort on their part to just coordinate all this and bring it all together.

Alex Blomley:

So thank you, Dave. Thank you, John. Thank you for your time today. And as we've heard, it wasn't just aeronautical engineering challenges, which made this project difficult to get off the ground very specific climatic conditions were needed to get a balloon six times larger than a standard hot air balloon, and capable of carrying a 2.5 tonne BMX bowl into the sky. It took nearly three years of planning, waiting, and weather watching forthis incredible project come to fruition. Thank you both for sharing your part of this story and this incredible challenge.

ve Boxall (Cameron Balloons):

And don't forget, if you haven't seen the video already, just any search engine, just search Red Bull Don't look down. And there are two really good videos. There's the video of just the flight and there's the making of video. They're both worth a look.

Alex Blomley:

Thanks for that, Dave. That's wonderful. Thank you all for listening. We will include some various links that Dave mentioned there in our podcast notes. Thanks for listening again, and we'll speak to you soon.


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