Building a racehorse – Nirvana Development Team SA

home
Building a racehorse – Nirvana Development Team SA

xc2


Little do most pilots realize how much work goes into the creations they fly. We see the visual candy with most manufacturers doing their best to design and color their machines to be visually appealing but the technical design challenges is what eludes most.

I have been fortunate to be part of the Nirvana test pilot team for a few years so I appreciate how much the company puts into making sure the product is well tested before it goes to market. As of late the company’s focus has changed from pushing development for slalom racing machines, to creating a platform for long range cross country racing. In past time the company mostly supported the pilots specializing in this field by sponsoring parts but the effort changed after the 2018 Icarus when owner Pavel Brezina experienced the excitement for himself. I don’t think he realized what a life altering experience it would be until the moment he found himself in No Mans land Botswana, alone and dependent on his wits and past experience.

The goal after the race was clear. Lets create a unique racing platform that would improve on everything we had available up to that point. The starting point would be the new F-Light 200. Initially it was designed to be a lightweight easily transportable footlaunch powered paraglider.

What is required?

Long Range XC is about power, fuel consumption, physical weight, speed, reliability and ergonomics. If you are out of balance with anyone of these you fall of the podium if not out of the sky.

If the machine produces more power than required, the pilot will have the advantage of overloading the max glider take-off weight but also will end up with a colossal fuel consumption. The pilot therefore uses the power to load more fuel but the more is loaded the higher the fuel burn and so the ‘evil cycle’ continues. Power for XC purposes is about being able to get the weight pilot and payload off the ground in the optimum take-off distance. Not the shortest possible distance.

That gets us to weight. If the optimum amount of power is produced at the cost of physical weight, then the pilot will have a hard time to manage that physical weight on the ground during take-off and landing. Most machines are developed to have manageable weight but what is not factored into the equation by the manufacturers is the payload weight that will be added in a unsupported race like the Icarus. The payload also increases considerably if you have a machine that has a high fuel consumption because the pilot would have to increase the reserve fuel capacity in order to have a range that is competitive with other race pilots.

Fuel Consumption is really where the manufacturers earn their buck. With a dozen engine choices out there and frame designs of all shapes and sizes the manufacturer has got to come up with solutions to reduce drag or improve engine performance. The glider plays a roll in this of course but all things being equal, the PPG design has got to be as aerodynamic as possible and the engine has got to be as efficient as possible and there are too many factors to mention for the length of this article.

When it comes to reliability most pilots will tell you this is the biggest stress. Most Powered Paragliders will show no signs of fatigue for flight periods of 2 hours or less. When you add 40-50 kilograms of additional fuel/payload and increase the flight time to 4 hours and beyond, we start entering the realm of unpredictability. One only has to look at the number of race class finishers to see the reality of the above statement. The solution is to test, test and test some more and come up with solutions until the race machine eventually has high reliability. That might very well mean changing the engine type or exhaust type until the problems cease to exist.

When it comes to speed this is a matter of debate. All pilots would like to fly fast, but fast equals higher fuel consumption. I guess my position on the matter would be the ability to maintain an Optimal speed from an advanced glider. Of course this is only applicable to a race such as the Icarus where if you fly to slow you might be separated from race leaders by changing weather or daytime. The size of an advanced glider with reduce drag and with the better headwind penetration, will assist with fuel consumption. Maximum speed will once again effect fuel consumption and bring about the ‘evil cycle’.


When the going gets tough. Well its going to get tough and then some

My first Icarus involved using a Nirvana 230HL and although this machine is known for reliability it’s also known for being on the heavy side at 33kg. In fact, I was not able to escape the “evil cycle” during my 2018 Icarus. With allot of power from the 230, came the excessive physical weight. Weight that didn’t bother me when flying day-to-day, suddenly became almost unmanageable when the payload was added. More power meant more fuel meant more oil for the mixture (rules of unsupported race) and meant a bigger glider all while you as pilot remain the same physical size.My first Icarus X take-off resulted in an extended ground roll as I was overloading the glider and my bagged pods were blocking a portion of the thrust line. On the 1000 mile Icarus race I used a bigger glider to eliminate the ground roll but in the end I was trapped in the ‘evil cycle’ having to manage the colossal weight of 83 kgs of paramotor, payload, fuel all the while having a bodyweight of 82 kgs. Insane, enough said.

Starting from Scratch

The F-Light 200 had a few things going for it. The machine in its entirety only weighed 20kgs with the advantage that the skeleton or body of the PPG was moulded carbon fiber and offered fantastic aerodynamic properties. The engine combined with a 3-blade propeller set offered good performance but questionable whether it would be enough for the additional payload. The fuel consumption figures was what made most sense with 1.9 liters per hour at 50 km/hr cruise setting and 2.5 liters an hour at max speed cruise setting on the fastest Dudek paraglider the company produced. In theory this would mean using less fuel and consumables on a competitive range.

Low Hangpoints

First things first, the Low Hangpoints is a shock to the system of a Nirvana pilot. The F-Light 200 was only available in a Low Hangpoints configuration. I would have to spend a good amount of time getting use to the new configuration and in reality it was far more challenging then I imagined. After 50 hours of practice I was confident but still concerned. My honest comparison would be that Low Hangpoints were allot more sensitive to changes in harness settings, measurably worse during mid-day thermals and provided less control over the glider during take-off and landing than what I was use to with the traditional High Hangpoints configuration of the Nirvana Instinct. One could explain my experience off to the fact that I had too many hours on High Hangpoints and therefore I’m not a good candidate to judge but an argument is no end to a solution.

First Change

Fortunately for me Nirvana had already reacted to traditional customer reviews and started with the prototype development of the High Hangpoint harness. To my delight I was asked to be one of the test pilots for this program and the rest is history.

Weight

The weight at 20kgs was a winner and this also allowed me to redesign the required payload bringing my total take-off weight down to 132kgs that included reserve chute and 18 liters of total fuel. That’s a cut back of 33 kgs. Don’t under estimate the effect of 33 kgs. It’s the addition of a 12-year old child, or adult Labrador dog, or 2 jerry cans of fuel or the kitchen sink. When was the last time you did ground handling carrying a kitchen sink under your arm?

With less weight came a smaller glider option taking me from a Dudek Hadron XX 24 to a Dudek Warp 20. More speed, better headwind penetration and no ground roll as a result all the advantages of coming in 13kgs under the max take-off weight of the glider!


Reserve Tank

Besides the weight and ‘evil cycle’ I was contending with during the Icarus 1000 mile journey, the biggest thorn in my side or bum was my reserve fuel tank system. Something that worked perfectly turned out to give me two engine out landings on the Icarus. Once right after take-off at the starting line and the second one resulting me doing a landing in northern Botswana on the main highway leading to Zambia. Both situations could have cost me the race but fortunately preparation for race class also means upping your skill level to execute spot lands and interesting take-offs. The reason for my discomfort was the conflict between my baggage bag design and the standard Nirvana reserve tank fuel line which resulted in engine starvation when pinched by the side mounted baggage bag. One had to go and in the end I opted for a weird configuration of my own design. I butchered the standard tank so its only purpose would be to give a ridged structure to hold a bladder tank used by most pilots that don’t fly Nirvana. A bladder tank collapses as fuel is consumed and no amount of pinching of the pipe resulted in engine starvation. Problem solved.

Testing

The proof is in the pudding as they say so the real question on my mind would be if all the benefits would still be present if the machine was loaded to maximum and pushed to the limit. While in Low Hangpoint configuration with the 3-blade propeller the result was not what I had hoped for. The 3-blade propset was not getting to maximum rpm fast enough during take-off and also resulted in not enough thrust to maintain level flight at 43 kts. With allot of head scratching and Nirvana working hard at solving the situation, the simplest seem to be the winner. Nirvana designed a spacer kit that allowed me to remove one blade transforming the 3-blade to a 2-blade giving me an additional 1500 rpm and a quicker spin-up to maximum rpm with take-off.

With more power came more problems. Nirvana’s engine design in a nutshell is to increase longevity and reliability by reducing rpm but increasing power by compensating with displacement. Only sober minds can make sense of that. My engine was running on the maximum temperature with full trim out because the side mounted bags were obstructing the airflow as the design allowed for. Nirvana’s engineers are working their own design and that now excludes having my side mounted bags. My solution was to use turbo charger piping in such a way that it directed airflow to the cylinder more effectively dropping the max rpm temperature by as much as 30 Degrees Celsius.

With flight testing on maximum trim open I was able to fix the fuel consumption on 3 liters per hour which is less than half of what I was burning up on the Nirvana Instinct fully loaded.


Summary

If one studies the numbers of the Icarus it becomes quite evident that equipment design is as important as skill level. Without a doubt, winning pilots designed their equipment and layout to find the best compromise between power, fuel consumption, physical weight, speed, reliability and ergonomics to ultimately escape the trap of the ‘evil cycle’. The Icarus flight itself is only half of the adventure, the other half is made up of head scratching, engine out landings and long hours of tinkering.
NEWS

© 2014 - 2019 NIRVANA SOUTH AFRICA
Tortuga ThemeZee