making the Leonardo hang glider

The article below has been written for pilots, however any editor who would be interested in a similar article written for general readership, please contact me and I can ask the BBC for permission to publish.

Standing on the hill side, Pisa and its leaning tower could be seen in the distance as the sun casting its last rays of the day, headed towards the horizon. The scene would have been magical with Leonardo da Vinci’s hang glider gliding down towards the setting sun. However, if da Vinci had built his design, he would probably have had a number of minions to pitch off the hill to an untimely end, whilst he perfected the design. But we didn’t have a large number of minions to sacrifice, we only had Rob Whittall.

At the end of June I had a call from BBC Producer, Tim Dunn. His call was the start of a fascinating project to produce a hang glider from the one and only sketch that Leonardo da Vinci had made of one. It was known that da Vinci was fascinated by flight and his other flying designs were of ornithopters, which we know don’t work and his involvement with kites. Tim emailed me a copy of the sketch and a photograph of this design built in the early 1980’s. The builder of this design had been asked to rebuild it for a BBC series on a number of Leonardo da Vinci projects and to see if it would fly. My task was to find a pilot willing or mad enough to fly it and locations here and in Tuscany. After some initial research, I travelled to BBC White City with photographs of leading hang gliding pilots, some ideas and information I had put together on flying sites in Tuscany.

The decision on the pilot was made in seconds, all I had to do was persuade him and one call later, we had World Hang Gliding and Paragliding Champion, Rob Whittall on board. I had found photographs of a site in Tuscany, which looked ideal and via the web was able to contact the Pisa paragliding school owned by Walter Bardi. With both Rob and Walter in place things were going well. At that stage too well, as Tim called to say that could I arrange the hang glider to be built also, as the original builder and the BBC could not agree terms. I knew the idea that the glider was to be made of bamboo and contacted two UK hang gliding manufacturers to discuss this proposal. As this was now August, filming dates were to a tight schedule and this was the height of the European competition season, my attempts to contact them proved fruitless. Where to go to next, was my dilemma. I then had a brain wave, as not far from me, living on the Norfolk Coast was Simon Sanderson. Simon is a paraglider pilot, but also an expert on building world record breaking yachts and windsurfers. A hang glider is only sail lying down, so Simon might be my man.

Simon took to the idea with great enthusiasm and within a week had built a scale model taken from the Leonardo sketch. Tim came up to Norfolk and we filmed the first attempts with the model to see if it would fly. Again and again the model was thrown and filmed in not ideal conditions. Did we learn anything? Well actually lots with regards the centre of gravity and its tendency to yaw one way before diving uncontrollably. However, from these lessons, Simon felt confident he could build the glider and it would fly. However, before building we needed to establish what we were going to build and why. History told us the Leonardo da Vinci would have probably used bamboo, this we could source. Secondly the sail cloth would probably have been resin coated cotton which again was not a problem. It was agreed that we were attempting to build the hang glider being as true as we could interpret it from the sketch. Our aims were then to build a glider safe to fly as possible, but one which would be able to perform unaided in free flight without the need of tethers to kite it. For these reasons we opted to stay with the bamboo, but as we knew we didn’t need to prove that coated cotton would work, we opted on the side of safety and decided to use a modern sail cloth. The three of us agreed, that the integrity of Leonardo’s design shape was the important aspect, not the detail on all the materials used. We also had to look at the number of times the glider would be rigged and de-rigged plus that it had to be freighted to Italy.

With bamboo sourced, Simon experimented in shaping the bamboo to give the glider its leading edge. He soon found that the 3 to 4 inch bamboo would prove impossible to curve and if it did, would it continue to hold this shape. With a home made steamer, Simon discovered that lengths of normal garden sized bamboo were ideal to make the leading edge curve. Steaming the lengths and interlacing them, he was able to produce the width and shape required plus in the event of any damage these individual interlaced lengths held together with cable ties could easily be replaced. Simon cut and sewed the sail cloth in four sections, adding a keel pocket to enable him to create the aerofoil shape. With the wing made, control in flight was the next concern. With Leonardo’s sketch was some very undetailed text which the BBC had kindly got translated for us. This text and from what could been see on the sketch, seemed to infer that the flight controls were a pole with a T-bar at the bottom with lines coming from the bar to the wingtips, nose and tail. His explanation was that the pilot would stand on the T-bar and via pulleys pull on these lines to control, pitch and roll. We enjoyed humerous discussions on this basic lack of control and though Simon built the pole and T-bar, we both knew this was not going to work. Simon and I discussed what control we could put on and decided that what we were trying to prove was whether the design of Leonardo’s wing would have flown, not his controls. To make it possible to see if the wing design would work, we decided the best option would be to fit a modern hang glider A-frame. We ran this pass Tim and he was in agreement with our decision of what were the aims of the programme and making the wing fly was the target.

On a fanstastic August afternoon, the glider was ready for its first full rigging. Tim and his assistant director, George came to Norfolk and Simon, myself and local hang glider pilot, Bob Cogman carried the parts out to the playing field in Brancaster Staithe. With one camera set on time record and Tim filming with another, the parts were laid out and Simon started assembling the glider. Bamboo cross tubes, keel and leading edge were lashed together once the sail had been threaded through. Slowly it came together and with Leonardo’s original idea of a control pole attached, we were able to roll the hang glider over ready for its first run. As was thought, the pole made it nearly impossible to run with, however in nil wind, we were able to see for the first time, the sail billow as Simon ran across the field.

The BBC’s next plan of action was for three days filming in September. The first day was at Rufforth near York, with the BHPA hang glider test rig. Steve Elkins, now back from European competitions had made the A-frame control and thankfully for his intuition, he came with a kingpost ready to fit the glider. Mark Dale rolled out the US made test rig truck whilst Simon rigged the glider. Once ready the glider was brought out of the hangar and the three of them had goes of running down the peri track. It was great to see the glider as it lifted from their hands as they ran into wind. The glider wanted to fly.

However, once on the test rig, things were different. The wind was slightly off to one side and though footage was shot of the glider on the rig as it travelled down the runway. I cringed, worried that we would do some major damage to it, as at times it would involuntarily start doing asymmetric tucks. Thankfully Steve bringing a kingpost saved the glider, as without it, I’m certain the glider would have folded. I was and am certain Tim and Simon were very relieved when the glider was final taken off the rig without any major damage.

Next morning the crew all headed off to Liverpool University for our trials with the model and testing of materials. Rob had flown in from the south of France and caused great amusement as he flirted with the very attractive, University professor, Caroline, who took the material testing very seriously at first. Original plans were to do the first flight tests in the Dales on the last day, but the forecast was for rain and strong winds then, so leaving the film crew to do close ups, Rob, Simon and I headed for the Dales to meet up with Ian Currer. Ian had kindly loaned us his sites and we arrived to set up the glider for when the film crew caught up with us. With glider rigged this was Rob’s first sight of the design and was highly impressed with build simplicity that Simon had created. With Rob kitted up, we were now ready to see if this 500 year old glider design would actually fly. A gentle slope, no wind and not a cloud in the sky, Rob lurched purposely down the hill. As with the model, the glider yawed left and dropped its nose. Experts were on hand though, Rob’s father Noel, one of the first people to hang glide in the UK and Ian Currer were able to discuss opinions on the yaw. After a few similar attempts it was Noel who correctly pointed out that by moving the A-frame and hang point back, might solve the problem. Now Rob’s attempts saw the glider lift from his hands, but maintain directional stability. Unfortunately the wind was light to nothing and though Rob did get his feet to leave the ground, a gentle breeze, would I’m certain, have seen the glider leave the ground and glide for a few seconds. However, we were all satisfied with our efforts and Tim was very satisfied of the footage they had shot.

The BBC liked to keep us on the move, so next morning it was back to Liverpool University to shoot the model in the wind tunnel. The engineers had had the model for a few days, so very interestingly from the data they had from their tests, they were able to put these configurations into a computer flight simulator. The fully hydraulic helicopter simulator was loaded with this data and Rob was able to fly the machine, as if it was the hang glider, though flying with a joystick. Interestingly the simulator confirmed our believe that the glider flew slow with a high angle of attack, it also confirmed that pulling the bar in, caused yaw and then dropping of the nose into an uncontrollable spiral to the deck. With practise, Rob was soon able to fly the glider, putting in gentle turns and finally landing it. However, we all knew too well the yaw characteristics could prove fatal on the real thing.

As with all BBC productions time and budget are the highest constraints, and so ideally before leaving for Tuscany we would have liked to have had time to attempt some more test flights. With only two weeks between Liverpool and the Tuscany shoot, we only had time to pack and ship. Though to add a final touch, Simon, I and his girlfriend Carolyn painted the famous Leonardo Vetruvian Man onto the gliders top surface.

The hills overlooking Pisa, are perfect for flying from and Walter Bardi took us up to take off to view the take off and landing field. Immediately on seeing the site, Simon and I knew Rob wasn’t going to fly the Leonardo glider from here. The take off was fine, the landing field was long even though Rob would have to put in a 90degree turn to get into it. But unfortunately we knew from this height that should the yaw instability occur then the programme would end with an “in memory to Rob Whittall” note. Rob arrived with David Dagault, having driven from the Ozone office in the south of France, and agreed with our assessment. Even so, before even considering this site we would need to do some low level testing. Walter directed us all to his training sites, south of Pisa, perfect grass hills in the beautiful Tuscan countryside. The glider was rigged again and unfortunately again we had no wind and with no wind also arrived light drizzle which turned to rain. Thankfully it cleared later and Rob attempted to launch, but again though he got airborne, some wind would have enabled him to glide. Our problem with no wind was the length of the glider in comparison to its wing span. As Rob ran and the glider lifted in his hands, the tail would drag as he pushed out to lift off. If he pulled in to try and gain more speed, the glider would again yaw and dump him into the hillside. Covering the glider for the night, we returned to our hotel to drown our concerns with some nice bottles of chianti, hoping tomorrow would be better.

Today was our last day to get it right and to add to our stress, Alan Yentob, Head of BBC drama, who is narrating the series was due to be on location with us. A beautiful warm cloudless day, but again the wind wasn’t helping being very light and from behind. Our patience was wearing thin, but slowly the wind swung round onto one of the hills. Again and again we had a problem with the yaw stability and Simon was convinced we had to go with a modification which he had tried on the model, the fitting of a tailplane. As we had to get some piece to camera shots of Alan Yentob flying on a dual paraglider with David Dagault, we left Rob and Simon fitting the tail, with George and a camera to film any improvement. We got the required dual paragliding shots as Rob and Simon returned to say they’d got it to fly. Unfortunately light was fast going and Rob was needed to demonstrate for the opening shots of the series, him throwing a paraglider about. So though we got some flying footage of the glider, we were not totally happy with the final result and unfortunately we had completed our time schedule in Tuscany.

We all returned home and Simon, Rob and I all felt that we had completed our task, but in the back of our mind we felt the glider could have done more.

In discussion with Tim, we felt we needed one more day in the UK and hoped the BBC would find the budget to enable this to happen. With a budget available, unfortunately I was unavailable for the set day as I was booked to be in Belize scuba diving. Luckily Rob had to be in the UK for his brothers wedding, so a day was set and with Simon watching the weather forecast, it was decided to have everyone ready to go to where ever it might be possible to fly.

November 18th, 2002, 500 years after Leonardo da Vinci designed his hang glider it flew as we wanted and had hoped for. Five times Rob flew it, from sites loaned to us by ParAvion in Wiltshire. The longest flight was 18 seconds, which considering the design, the bamboo and the age of the design was no mean feat.

In conclusion of this project, I have spoken to all involved and have come to some conclusions. Rob has told me, that he wouldn’t be here today if he had attempted to fly it from the large hill in Tuscany. But he feels very privileged to have been able to fly the glider. Simon did a fantastic job building the glider, his thoughts from an early stage were that the sketch was not the sketch of the final design which Leonardo might have intended, but a sketch of a model.

In the sketch is a line below the control pole which looks like a balancing pole that a tight rope walker would use. Simon believes this may well prove that Leonardo knew that the glider had a yaw problem and a balancing pole on a model would work similar to adding a tail plane. Some experts have said that many of Leonardo’s designs had a flaw in them and these flaws he kept to himself, as in those days there was no patent laws, so it was self protection of his designs. I’m certain he never did build the glider, because if he had built it he would have discovered many of the problems we incurred and like Simon, would have probably discovered the tail plane. Also if he had flown, we wouldn’t have heard of the Wright Brothers as man would have flown 400 years before.

What ever readers of this article or viewers of the forthcoming programme think of our efforts in recreating a pice of history, it has been a privilege to work with all those involved on such an interesting project. However, in our attempt to kill off Rob, we kept saying “ Its only television ”

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