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NERO History
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History



Inhoud
1 1959 - 1968
2 1969 - 1970
3 1971 - 1974
4 1975 - 1982
5 1983 - 1991
6 1992 - now
On this page you'll find a brief description of the history of NERO.


1959 -
1968

The beginning of NERO
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The Dutch Federation for Rocket Research (in Dutch: NEderlandse vereniging voor Raket Onderzoek - NERO) was founded by students from the University of Leiden in 1959. Soon after that, students from the Technical University of Delft joined. In 1965, NERO joined with the VARO (United Amateur societies for Rocket Research, in Dutch: Verenigde Amateurverenigingen voor RaketOnderzoek). At that moment, the VARO had departments in Breda, Eindhoven and Purmerend. It was decided to continue under the name NERO.

Throughout the first few years of NERO, priority was given to the development of rocket motors. It was decided to concentrate on Zinc-Sulfur propellant, which was, and still is, a combination much used by many amateurs at that time. This was probably inspired by an America booklet by Capt. Bertrand M. Brinley called "A guide to Amateur Rocketry". Black gunpowder was also considered as propellant because it had resulted in some good results before. However, the Zinc-Sulfur combination propellant is a prominent for 25 years now and has shown to be a very reliable propellant in those years.

Rocket propellants

For a long time, the rocket motors of NERO used a mixture of Zinc and Sulfur, or a mixture of Zinc, Sulfur and Aluminium. During burning of these mixtures, the following chemical reactions takes place:
Zn + S -> ZnS + Energy
2Al + 3S -> Al2S3 + Energy
Mixing and condensing of these components to a homogeneous propellant mixture is not without risks, as demonstrated by an accident which happened in 1980. In this accident, the rocket propellant ignited during mixing and homogenisation. Ever since, NERO has used a 'pile driver' to condense the propellant components. In this method, the rocket motor is place upside down into a pit below the ground level. The pile driver block is mounted hanging down from a steel tripod which is placed over the pit above the rocket motor. The pile driver block can be moved up and down vertically by remote control by means of a simple rope. By stepwise adding and pounding the propellant with the pile driver, the mixture can be condensed safely.

 



1969 -
1970

The beginning of NERO Haarlem
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NERO Haarlem originated from the former Karel van Manden Lyceum in Heemstede. At that school, student formed a working group Techniques during the winter of 1969. This group was supervised by the cosmology teacher and quickly set itself the objective: "to show that it is possible for high school students to safely experiment with simple solid rocket propellants".

In the summer of 1969, this working group was able to get accommodation at the model airplane society "Anthony Fokker" in the Vogellaan in Heemstede. This accommodation proved to be an ideal place to experiment with small solid propellant rockets. After a while, the working group really felt at home with "Anthony Fokker", so they decided to join this society collectively. The working group Technics from the Karel van Manden Lyceum thus became the rocket section of "Anthony Fokker".



1971 -
1974

At the model airplane society "Anthony Fokker"
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During the years in the Vogellaan, the emphasis was put on the development of reliable solid propellant rocket motors. For this purpose extensive tests were performed with test motors. About 25 tests were executed with varying propellant mixtures and nozzle exhausts in the period from 1969 to early 1971. Special test motors were developed for this purpose only.

Besides the test motors, the  facilities to test them were also developed. Two different methods for measuring the rocket thrust were developed: the 'spinning disk' and the 'pendulum rig' methods.

In the spinning disk method, the rocket is attached tangentially to a horizontal disk. This method is equivalent to the spinning disk displayed in some Chinese fireworks. Upon ignition of the rocket, the disk starts spinning. Both the total number of revolutions as the revolution time is a measure for the exhaust velocity of the gasses and thus for the efficiency of the rocket motor. The number of revolutions is determined mechanically and the total burning time is measured with a stopwatch. This method is particularly suitable for comparative research.

The pendulum rig is a platform which is cardanically suspended on four chains and on which a rocket motor can be mounted. By measuring the excursion of the platform, the rocket thrust can be determined. A glass plate covered with soot is used to generate a thrust curve (thrust as a function of time).

Besides the above devices, the group was equipped with a wooden test rig, which could be placed in a pit below the ground level to minimise the risk accompanied with explosions. A rocket motor was placed upside down in the pit and subsequently tested. This test set-up was particularly suitable for testing the more powerful rocket motors. A battery was used to electrically ignite the motors.

All these activities finally resulted in the launch of the first Haarlem rockets, designated H1 and H2 (H for Haarlem). For the launch of the third rocket, H3, an adjustable launch tower proved to be necessary. In 1974 the wooden test rig was replaced by a steel one.

Launch devices

Rockets use tail fins to improve their stability. However, these fins are only effective when the rocket has reached a certain velocity. Therefore, additional stability during the first phase of the rocket flight is provided by a guidance rail or a launch tower. At this moment, both systems are still in use, with the guidance rail primarily used for small rockets and the launch tower for the bigger rockets.  NERO has the disposal of several launch towers, of which the largest one is 5 meters tall and is secured with steel mooring wires to the ground. In this tower, four guidance tubes are mounted to guide the rocket. The rocket is placed within these four tubes. The guidance tubes can be adjusted to accommodate different rocket diameters.  With this tower, launching multi-stage rockets is also possible.

The H3 launch was conducted from the newly built 5 meter launch tower and took place at the end of March 1974.  The rocket reached an altitude of nearly 1 kilometre and landed on a sand bank just off-shore. After this success, the group more or less disintegrated because of high study demands and the rocket activities were reduced to a very low level. The launch tower was put into storage at the "Anthony Fokker" society.

An important change in those days was the society of the Young Researchers group (in Dutch: De Jonge Onderzoekers - DJO). The DJO department Haarlem had accommodation in 'the Egelantier' in the centre of Haarlem. Members of the rocket section of "Anthony Fokker" played an important role in the foundation of DJO-Haarlem. It was therefore logical that the rocket activities were to be continued within the DJO-Haarlem.



1975 -
1982

At the Young Researchers (De Jonge Onderzoekers - DJO)
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During the beginning of this period, a test motor was manufactured for the DJO at the University of Amsterdam, taking an earlier NERO rocket motor as an example. However, after this, several years followed during which most of the rocket activities more or less came to a halt, even to an extent that not much is know about this period. This continued until 1978, when the rocket activities were picked up again, which resulted in the foundation of the working group Rocket Technology within DJO-Haarlem. Initially, this working group mainly concentrated on the development of electrical igniters.  The end product of this was a very reliable and reproducible igniter, which never failed during tests. In 1979, a so-called 'device for igniting solid propellant rockets' or ignition box was developed. This made it possible to reliably and safely ignite rocket motors from a distance of hundreds of meters . This type of ignition device is still being used nowadays.

Because of all these activities, the working group progressively attained a more professional character. An unfortunate accident with rocket propellant gave rise to an investigation into the possibility of covering these type of activities by an insurance policy.  This proved to be financially unattainable for the group. However, it was found that the Dutch Federation for Rocket Research (in Dutch: Nederlandse vereniging voor Raket Onderzoek - NERO) had already such an insurance policy. In 1980 it was therefore decided that the rocket activities would be continued within the NERO, resulting in the foundation of the department Haarlem of the NERO.



1983 -
1991

At the NERO
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The development of the H4, which was a middle-sized rocket, was now initiated. For the H4, the launch tower was required again, so that the tower still in storage at the DJO-Haarlem was recovered after many years. Unfortunately it was found that the wooden framework of the tower had completely disappeared. The NERO Haarlem group had to reconstruct the missing framework and several improvements were made to the construction of the tower. After this, the development of the H4 rocket motor was continued and several ground tests were performed. NERO Haarlem also developed a rocket section which contained the parachute system and which was put on top of the motor section. The 1.72 meter tall and 7.8 kg heavy H4 rocket was launched in 1983. The flight was a complete success and the rocket was recovered entirely and undamaged.

A public nuisance act license was requested and issued by the authorities in order to build and use a static test bench, which was to be used below ground level only. Furthermore, the electrical ignition equipment was modernised and two small test motors were manufactured. In between these projects, a test series was completed which was required for the future conversion from nozzle exhaust ignition to top bulk head ignition.

During the following years the Haarlem department of NERO became active nationally and some international contacts were also made. This resulted in the delivery of parts of the instrumentation for the so-called Interim project to NERO department Drechtsteden. A lot of experience was gained in measuring pressures and temperatures on-board a rocket. In the mean time, several members participated in a NERO working group in order to develop more efficient and powerful rocket motors.

Around 1986 the construction of a totally new rocket, the H5, was started which would have to result in the launch at the first Dutch Launch Campaign in 1987. It was decided to take a quite powerful Yugoslavian motor and to build the rocket around that motor. The launch date, 30 May 1987 was just attained, thanks to the dedication of many people in the final days before launch. The flight itself took place in heavy fog, which meant that the rocket could not be tracked with the naked eye. The flight was not successful due to a fault in the electrical system which caused the deployment of the parachutes just 3 seconds after launch. Because of the high velocity, the parachute were completely torn off and the rocket continued its flight ballistically up to the highest point and down to Earth, making a lot of noise. The rocket was totally shattered upon impact with the ground and virtually nothing could be recovered, this included all the data recorded by the instruments on-board.

From motor construction to rocket construction

In the course of the years the emphasis at NERO Haarlem has shifted from the construction of rocket motors to the construction of rockets itself. In the beginning, when rocket motors were not readily available, the main objective naturally was to build the motors. However, at this moment, NERO is assured of the delivery of several reliable and re-usable solid propellant motors (the Penta series). NERO Haarlem is using these motors at this moment and has concentrated more on the construction of the rockets. Because of the increase in the reliability of the rockets en the availability of reliable parachute systems, it became possible to launch the same rocket more than once. This led to the development of complete launch programmes (H6 and H7), which have flown several times, just like what is possible with the Space Shuttles.

After the first Dutch Launch Campaign, the activities regarding rocket construction within the department slowed down somewhat. NERO Haarlem published a bi-monthly bulletin and the contacts with other clubs, both national and international were numerous. The construction of the follow-up rocket (H6) however, did not fully materialise. During the year 1989, in which NERO celebrated its 6th lustrum, several 'political' troubles caused the construction of rockets to come to almost a complete halt. Out of 'political' considerations the NERO society was reformed in 1992 into a federation with separate, independent departments. Since 1 June 1992 NERO Haarlem is an independent society with its own regulations, which is affiliated with the Dutch Federation for Rocket Research (in Dutch: NEderlandse federatie voor Raket Onderzoek - NERO).



1992 -
now

Independent society
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The increase of activities accompanied with the change-over of the society made it possible to organise the second Dutch Launch Campaign (in Dutch: Nederlandse Lanceer Campagne - NLC-II) in September 1992. Despite the late start of the construction of the H6 rocket is proved to be possible to launch it during this NLC-II. The H6 was originally intended as an improved version of the H6, but in the end it was completely designed from scratch. The launch of this rocket (designated H6A, because it was the first flight of the H6) took place on 26 September 1992 and was a complete success, with full recovery of the rocket, which did not sustain any damage. The H6 flew a second time as the H6B, before crashing - due to wind gusts - as the H6c. The extensive on-board electronics however made it possible to provide us with a wealth of information concerning the flight of the rocket, its behaviour during flight and its performance.

Rocket trajectories

The velocity of a rocket at its highest point is mainly determined by the trajectory of the flight. When a rocket is launched vertically (90), the velocity at the highest point, just before it start falling down tail first, is zero (this can be compared with a ball thrown straight upward). When a rocket is launched under a different angle (e.g. 82) however, the flight will follow a trajectory which is very close to a parabola, causing the velocity never to be equal to zero. This situation is ideal since it will allow for the parachutes to be deployed in a controlled manner. When the launch angle is very shallow (more or less horizontal), the velocity at the highest point is so large that it might cause the parachutes to be torn off from the rocket. In the case of the H6, a wind gust caused the launch angle to decrease dramatically, which evidently led to the loss of the parachute and thus the rocket itself.

The success of the H6 project formed the basis of the H7 project. The H7 is based on the H6 technology, but has two stages instead of one. The H7 is - with five successful launches - one of the most successful rockets ever. With the H8, NERO Haarlem launched the first amateur canard controlled rocket in the world. With the H10 we will break the European altitude record for amateur rockets. read more about these projects on the project pages.

At this moment, NERO Haarlem has about 20 members. Besides these people, NERO Haarlem can rely on the ad-hoc technical support from a group of people for our projects. These people manufacture parts and/or assemblies on request or provide valuable advise and/or calculations. Because of the geographical dispersion of its members, NERO Haarlem does not have a permanent accommodation. The work for projects is mainly done at home, while the Free University (in Dutch: Vrije Universiteit - VU) of Amsterdam provides accommodation for group meetings and work.

Design strategy for rockets

Completing the construction of a complex two-stage rocket like the H10 requires a lot of time. Not so much the manufacturing of the components as the design itself and the tests of the components are responsible for that. That's the reason why NERO Haarlem has been quite conservative in constructing rockets for some years now.  Systems which have been proven to work during flight are re-used again and again.  Innovations are only used when a meaningful contribution is guaranteed.  Throughout the design, simplicity and reliability are important. Systems and components are not designed more complex than necessary.  Fault trees are specifically taken into account during the design, with the intent to minimise the loss (i.e. crash) of a rocket.



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