The Human Power Team is a student team co-operative between the Delft University of Technology and the VU University of Amsterdam, with the objective to design and build an aerodynamic recumbent that is meant to break the world speed record.
The team was founded in September 2010, and in September 2011 it obtained a European and student record with a speed of 129 km/h, and in September 2013 that new world record was placed at 133.78 km/h, both by the cyclist Sebastiaan Bowier. This happened at the yearly World Human Powered Speed Challenge event in Battle Mountain, Nevada, United States of America.
At this moment, the fourth team of students is preparing for the new world record attempt with a new high-tech recumbent: the VeloX4. The technical part of the project is in the hands of the students from the TU. Just as important, is the guidance and training of the cyclists, which is in the hands of the VU students. This co-operation makes the Human Power Team a unique student team.
Friday, 07 March 2014 22:11
Last Friday we revealed the design for our new record bike, the VeloX IV. For those who missed it we present the highlights of the design divided into six parts.
Wheels and Tyres
The VeloX IV will make use of the same 5 spoke magnesium wheels as her predecessor. These 19 inch wheels, made by Flevobike are used together with Michelin's special radial tyres made for an extremely low rolling resistance. These tyres have approximately half the rolling resistance compared with regular cycling tyres.
Unlike the VeloX 3, the new design features front wheel drive. With the relatively small wheel, a large gearing ratio is necessary to achieve speeds in excess of 130 km/h. Therefore, an extremely efficient planetary gear with a ratio of 1 in 4 is placed in the front wheel hub. This results in a shorter chain, which in turn leads to a more efficient system. In order to make sure the rider isn't bothered by the driveline in between his knees, a mono fork is used instead of a regular two sided front fork. This mono fork in combination with the convex wheels results in a very compact system giving our rider sufficient space inside the bike.
In order to provide enough cooling and oxygen for our rider, an air inlet will be placed at the stagnation point, a the front of the bike. An air outlet will be placed behind the riders head. What is new this year, is the extra cooling on the back, in addition to the cooling of the head. This is achieved by a second tube leading from the air inlet to the seat of the VeloX IV. With this extra cooling, outside temperatures of up to 30 degrees can be sustained for an hour.
This year the streamlined shell will be split horizontally. The lower shell will, in combination with two 'rollbars', form the carrying structure of the bike, whereas the upper shell is mainly for aerodynamic purposes. The horizontal cut will lead to a lighter bike and provide better access to the bike components. For the cyclists protection, two bulkhead will be made between the seat and the hind wheel. The hind wheel is also suspended to one of these bulkheads. The suspension is designed in such a manner that the hind wheel can be lifted out of the bike in case of necessary replacements. Last but not least, the front fork is secured to the bike through the front wheel frame.
Inspired by previous years, the sight of the cyclist will be made possible through a camera system. As opposed to previous years however, there will be an HD camera and full HD monitor as a primary system to improve the cyclists vision, and a VGA camera and screen as backup. The cameras will be placed in an aerodynamic camera bubble. Furthermore, the upper shell will have a small side window in case both cameras fail.
Since the air resistance comprises almost 80% of the total resistance, a lot of attention and time is invested in improving the aerodynamic shape. By making use of the so-called 'Stratford pressure recovery', the new shape is almost 10% shorter as opposed to the VeloX 3, which leads to a 20% decrease in air resistance.
With the new design we will try to break multiple records the coming year, both for men and women. The two selected riders will be presented to the public this Friday the 7th of March at the VU University in Amsterdam starting at 14.00.
Also this week, the production of the VeloX IV will start in Delft, beginning with the production of the aerodynamic body and frame. Keep checking our Facebook, twitter and website for updates.
Friday, 07 February 2014 14:32
The search for a female rider continues. In the last couple of weeks we were searching for women who wanted to take the challenge with us through media like Radio 1, Radio 2, newspaper "de Metro" and a television program called "Editie NL". Approximately 60 women applied for the single position in the VeloX IV, so we had a lot to choose from. After a first selection, based on the questionnaires the women filled in, six candidates where chosen for the physical tests at the VU University in Amsterdam.
Last week, the women were tested on their sprint power through a 30 second sprint test (Wingate test) and on their endurance through a VO2-max test. Some women came in anxious, some came in happy, but all women gave us high expectations. There is certainly a chance the female records will be broken this year.
One of the test, though, almost went horribly wrong. One of our candidates brought the wrong pair of shoes with her. After a search of one and a half our through Amsterdam, some new pedals were found, so the test could be done after all.
The candidates left us with high expectations, but the hard task to choose one of the women. One with great endurance and de drive to train very hard in order to, hopefully, break two world records. Our final choice will be kept a secret until March the 7th. On this date, our two cyclists will be presented to the public at the VU University in Amsterdam.
Besides the presentation of the cyclists, another milestone in the project in coming closer by the day. The engineers in Delft are busy designing their parts in order to meet the deadline set on February the 28th. On this date, the design of the VeloX IV will be presented. More information on these two events will follow the coming week.
Friday, 24 January 2014 14:42
In an earlier blog you have read how we validated the new aerodynamic shape for the VeloX IV in the wind tunnel (LTT) at the Delft University of Technology. After the shape was validated it had to be tailored to our new rider's exact body shape and movement. In order to do this, an analysis had to be made of his movement on a recumbent bicycle. This was done with a stationary bicycle with the exact geometries of the VeloX IV, for example the seat height and orientation, the position of the bottom bracket and crank length. Through a video analysis, our new riders movement was measured during different cycling protocols (e.g. sprinting, easy pedaling). With these videos, the exact movement could be measured after the test.
After the data of the test was all gathered, a model was made of our rider. By linking the co-ordinates of the feet with the crank angle, a formula for the foot angle with respect to the crank angle could be derived with a so called "Fourier transform". This formula was implemented in the rider's 3D model to exactly simulate the movement of the feet inside the VeloX IV. All other dimensions of our rider were also implemented in the 3D model, which finalizes the model of our rider.
With this new model, the aerodynamic shape was again altered to precisely fit our new rider. After this was done, the shape was again validated using CFD simulations. However, using computer simulations to see if our rider fits in the shape isn't enough for us, therefore twenty cross-sections of the new shape were taken and milled into foam plates. These cross-sections were put over the stationary bicycle with VeloX IV's geometry and our new rider was put in it. By cycling at all possible speeds or power outputs we simulated every movement he will do in the VeloX IV. By doing this we could see if he fit in the new shape. Numerous photo's were made during this test by our photographer Bas de Meijer, you can find his photo's here.
The test gave us valuable information. The so called "footbox" was very accurate, but especially around the head a few centimeters of the shape could be removed. With these results, the shape could again be altered and made even shorten by placing our rider more upright. This resulted in a final aerodynamic shape with even less air resistance.
After the final shape was made, a mould for the production was designed. The mould will be made out of four parts which will make releasing the body even easier. Today, the moulds were ordered at MouldCAM. They will also take care of the high gloss finish, which will make for a better quality body. If everything goes according to plan, the production of the body will start at March the 1st at the Delft Aerospace Structures and Materials Laboratory (DASML) in the Delft University of Technology.
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