Home Contact Us Site Map
Thursday, April 19, 2018
Article written by Gary Mortimer

Two Get Very High Part One

So there we were, 30,000’ upside down, nothing on the clock but the maker’s name. All good flying stories should start with a line like that. For Lev David and I, it was sort of true.

Topping out at 30,334’, briefly we were the highest people stood outside anywhere. We shook hands and the feeling was humbling and then we had to return to a pressing need. Relighting the pilot lights, they had gone out 834 feet beforehand. I knew that the chances of getting them lit before we had dropped below 25,000’ were slim - the balloon factory in England had told me so!

The story began as so many do in a Beer tent. Splashy Fen 2004 Underberg Kwa Zulu Natal. I had met Lev David, producer and presenter of East Coast Radio’s breakfast show a month or two earlier. He stood on top of one of my balloons at the ABSA Stadium Durban. I was very impressed with his fearless manner.

Live on the show they had spoken via sat phone to a climber on top of Kilimanjaro, Lev asked if the balloon could get higher and I said of course. Reaching the height of Everest at 29,000’ and a bit seemed the way forward. With my beer head on, I had said the balloon could do it without really thinking about it. What would it matter we both would have forgotten the conversation by the morning.

The conversation was forgotten but only for a couple of weeks.

When revisited in the cold light of day, the problem of getting the balloon to height did not seem insurmountable. A quick check of the manufacturers slide rule load calculator proved that two of us could easily get up to 15,000’ with a couple of hundred spare kilos of lift in hand. Sitting down with the formulas would be required for an accurate idea of what we could lift higher. Time to ask grown ups for help.

I have a friend in Australia, Steve Griffin who makes a habit of taking small balloons to great heights. He holds several world records for one-man balloons and has even gone to the Arctic in order to get into efficient low temperatures. An email to Steve provided an excel spreadsheet which I had to modify slightly as he can’t get much above 18,000’ in a hopper. It had the maths sorted though. I ran the numbers and worked out that we would have at least 40Kg of spare lift at 30k.

Working the old saying, measure twice cut once, I checked with another grown up, Simon Forse, the technical guy at Lindstrand balloons in England. He sent this jaunty equation, based on a 180 at an internal temp of 100C

L = p x V

Therefore L = V x p0

Im = 3.28084ft

Where for 30Kft = 9143m or 9500m

P0 = 0.43890 kgIm3

T0 = 226.4 0K

V = 5100m3

T1 = 100 0C or 373 0K


L = 5100 x 0.43890

L = 5100 x 0.43890 x 0.39303

L max = 879kg

Ok so we could certainly lift the two of us.

Getting into the stride of things it was time to address the environment in which we would be operating. The Internet, modern source of answers to everything quickly painted a picture. We potentially faced temperatures of -60C in 110 knot winds generally from the North West. I knew it was going to be cold but –60! The wind speed mattered not, other than selection of launch site. As long as it was slow for the landing.

Every 18,000’ that you climb halves the properties of the atmosphere at sea level. We would be operating close to ¼ of sea level density. Less than half the available air obviously means much less oxygen for

1. Us

2. The pilot lights.

All pilots have heard of hypoxia, once again the internet provides answers without oxygen you would last… Times of Useful Consciousness

(Effective performance time)

Altitude Conscious time







50,000+ 5 – 12 minutes

2 – 3 minutes

45 – 75 seconds

30 – 60 seconds

10 – 30 seconds

12 – 15 seconds

12 or less seconds

Important also to realise that this is the time it will take you to become unconscious, at 30k death will follow after 2 minutes.

Obviously we would have to get the right oxygen equipment. I will not go in to great detail but the continuous flow systems often used in light aircraft for supplementary oxygen are not suitable for flight above 20,000’. A pulse breathing system and mask is required for higher altitudes and the amount of oxygen needed to be pumped at you increases dramatically.

Now when I started looking the only people that I could find that had that sort of gear were the military. The systems are used for high altitude parachute jumps by the Special Forces. Contact was made with the air force and at the same time SA flyer magazine, I figured they might well know someone who could help.

That was us, now for the pilot lights. In the past people have rigged up supplies of oxygen for the pilot lights but that is now considered rather dodgy. One hard landing and you have broken oxygen bottle feeding perhaps a tank fire. As you climb higher the burner flame starts to detach from the burner, moving higher. This is the point at which the correct mix of oxygen to support the flame is present. Eventually the flame will detach and disappear up into the envelope all by itself. To stop that happening you need to lean the fuel mixture. There are two ways, either moderates the flow using the tank valve or fit reduced jets. This is the option we took. Once above 25,000’ you leave the modified burner running continuously. A leaned burner means less power available. This will bring us up against a fundamental mistake made in high flight planning.

At sea level you can get about 220 kg per hour of fuel through the burners, burning flat out. Take those burners to 30k and the maximum you can get through is 20 kg whilst sustaining a flame. If you try and get more through it will simply blow out the flame too much fuel to air. You don’t have to be a rocket scientist to realise that you will not be able to generate lots of heat.

Load charts assume an internal temperature of 100C it is unlikely even with the burners operating flat out that you will generate that temperature. An internal temp of 80C is far more reasonable.

All further load calculations for the flight were made assuming an internal temp of 80C. This meant losing weight, from the equipment and from ourselves.

Going to a gym is a fairly alien concept for me but I knew weight had to go and fitness had to improve for altitude conditioning.

An unwelcome side effect of getting the equipment light for high altitude is the effect it has when you return to low level. If you do a really good job of getting the weight off and the internal temperature drops into the 40C range then you are in danger of going solar. The sun will keep you flying and make it devilishly hard to land; more especially stop on a windy day. That’s why when looking at the weather an overcast day might be a good idea.

Now we had an idea of what to expect, what sort of oxygen equipment we needed and what we needed to do to the kit. How long would it take? Another thumb suck approximation was made. Fuel for two hours should be enough.

Lev would broadcast live to the show and that bought a set of communication problems but radio being radio and not TV meant finding other ways to engage the listeners.

Live tracking of the balloon on the East Coast website was the method chosen. Time to find people that knew how to do it. By chance I came across Stuart Baynes from Joburg. He proved to be a great source of knowledge and eventually put us in touch with H Communications. They very kindly offered to build and find sponsors for the entire tracking gig.

It would be handy for the crew to be able to see where we were as well. If there was 110 knots of wind at altitude we would be a long way away quick. In order to do this we would need laptops. These were provided by HP one in the balloon and two on the ground.

The thought of high winds at altitude and a look at the charts and suitable landing areas pulled us towards choosing Estcourt airfield as a launch site. Another consideration was that if we had to standby for weather for any amount of time we could leave the gear rigged in a hanger and pull it out as required.

Next we had to make sure we would be allowed to climb to 30k in that area. Special use of airspace was cleared with CAMU for the first week of May which is when traditionally frost arrives in this wood of the neck. I must say that Tanya at CAMU was outstanding.

Lev sorted out clothing used by climbers on Everest, Foshini’s new outdoor clothing retailers, Due South kindly let us walk into a flagship store and choose what we wanted.

With bits coming together and knowledge being gathered we ordered the high altitude burner jets and once they arrived scheduled a practice flight. This was a month beforehand at the beginning of April. The idea behind that being we would have plenty of time to fix things or change stuff.

The tracking system required a relay station connected to an always on internet connection. It would also help if that was at a high spot. Andrew at the Antbear B&B in the hills above Estcourt helped with that. Rather annoyingly all the equipment worked at home and as soon as it was moved fell over. That meant that for the practice the only recording we would have would be from the following vehicle.

Unfortunately the weather didn’t play ball. The Saturday morning was forecast windy with rain. We took a decision not to drive all the way up to Estcourt and instead try and get as much done from home as possible.

We had hoped to fly four of us to 20k but with the forecast high speed winds at low level I was not happy carrying oxygen equipment kindly leant by Peter How of Composite Technologies I did not want to damage it.

It was all unravelling really. Still we went ahead with Charmaine from SA Flyer on board. As soon as we took off Henry informed us the tracking was not working. Lesson number one, we had put the tracking box in a different compartment to Lev. He had to climb across and open it up. Lesson number two, Henry had not turned it on!

Up we went to a very average 12,000’. Lev started getting used to driving the software for the 1:50000 maps that were on our laptop. All in all it was a fairly pleasant flight landing ironically on the other side of the highway from Estcourt airfield.

It may not have been a thundering success but it did get all the players together at the same time and introduce those that had not seen balloons before to what happens. It also gave what had now become a team, a more focussed and real goal.

Next came high altitude training with the air force at Waterkloof there we were taken without oxygen in the hyperbaric chamber to 20,000’ and then left to sit a while and become hypoxic. To be honest the chamber was the thing that I was most afraid of and the reason that I had been dragging myself to the gym every morning for two months. I had lost very little weight, only 6kg but was feeling much fitter. On average I was doing 22km a day on the machines.

Our blood oxygen saturation levels were measured and at the start Lev had a perfect score of 100 I lagged behind at 96 percent. Lev being only 24 and much fitter and leaner than me had not been as diligent with his training. I was somewhat miffed. Having sat a while our oxygen levels were checked again and Lev had dropped to 67% and I was happily a whole 11% better off at 78%. We can only put it down to me living up here at 4000 odd feet and training harder. Reviewing the video of our trip in the chamber you can clearly see us joking more and I vividly remember thinking how heavy the camera was becoming. On the way down at 4000 fpm my ears really started hurting after only two minutes I was complaining. The Sgt Major controlling events outside slowly took us back up to 18k again and then we started down again at a more leisurely rate. On examination by the doc afterwards my ear wax was said to have moved and blocked my left ear. Nice very nice.

The next day both Lev and I felt exhausted.

Many promises had been made by many people about the oxygen gear. This was what the flight hinged on. We were let down by a couple of companies and in the end I resorted to discovering who made the gear used here by the military. I found the company in the UK and they agreed to send me a couple of units. The only snag was that they are considered a weapon and we would have to apply for permission to import weapons! All too difficult with less than a month to go a real pain.

Another return to the internet and now I was looking probably where I should have been in the first place, the climbing world. I quickly found equipment from Mountain High and established that it was good for heights of up to 31,000’. As luck would have it they had an agent in South Africa. By chance he shared a combination of Lev and my surnames, David Mortimer. That omen seemed good and David let the project live once more. Not only does David import the gear he also fly’s it in his gliders and is the president of the Soaring Society. He would act as our official observer.

With two weeks to run I started tracking what the upper air winds were doing and plotting accurately where we would be taken.

Talk is cheap so it was time to fly.

Related Searches

pilot light