“When the countdown reaches zero, it is our turn”

 “When the countdown reaches zero, it is our turn”

Spark plugs for rockets. Simply stated, that is the main product of Aerospace Propulsion Products (APP) of Klundert (Brabant, Netherlands, ed.). Over one hundred Ariane-5 rockets were launched using the ignition system of the Dutch company. Its lesser known Vega launcher was launched sixteen times with the help of APP.

“We are doing the coolest thing in the whole rocket,” said Edwin Vermeulen, CEO of the company. “Everyone knows the countdown. When we get to zero, it’s our turn.” At that moment the igniters of the company do their job: they ignite the engine, which then propels the rocket up. Vermeulen: “If our igniters fail, the rocket doesn’t launch.”


Not that the product has ever faltered in APP’s fifteen year history. “Sometimes it goes wrong, but so far it has never been due to our product.” If things go wrong in the form of an explosion, the employees of APP can see from the location of the explosion whether it is related to the igniters or not.

Except on July 10 last year, when a Vega (a 30-meter launcher for the transportation of small satellites) was launched from its base in French Guiana. At around 4 a.m., two minutes after takeoff, things went wrong and the rocket exploded.

Something wrong

“I woke up in the morning with several messages on my phone that something was wrong,” says Vermeulen. “At a time like that it is not immediately clear what is going on. It is therefore especially important to stay calm and let the customer (the launcher manufacturer, ed.) do their work first. We immediately started collecting data with the team. Within two days we had everything together. A week later the customer was here and we investigated everything together. In the end it turned out that it was not our fault. All in all, we spent about a thousand hours researching.”

Disastrous consequences

APP makes a modest impression among all large companies in the Moerdijk industrial estate. The company consists of seven small, flat buildings spread over a 3.5 hectare area. The great distance between the buildings is all because of safety. One of the buildings contains explosive materials, that are mixed with other substances in another building and processed into highly explosive rocket fuel. Not a liquid, but a rubbery substance, which is subjected to extensive tests in another building. Strict safety requirements apply in the buildings. Just a single spark can have disastrous consequences.

Spark plugs

“Two of these are supposed to ignite the rocket engine. They are actually very powerful spark plugs,” says Vermeulen, while showing an igniter. A steel casing of approximately 20 centimeters in length and a diameter of approximately 7 centimeters, which indeed reminds of a spark plug.

“This tube contains the fuel. The trick is to make an igniter that makes a flame at just the right time, at just the right size and at just the right power. Making such a flame is a skill. The flame behaviour depends on the chemistry and shape of the fuel. It must also be stable. When a rocket is launched, it shocks and vibrates from all sides. The fuel must not explode because of that.”

Fire extinguishing systems

While igniters are an important part of the business, the company has expanded its product range in recent years to be less vulnerable to an economic recession. APP uses the expertise it has in the field of igniters to develop fire extinguishing systems. For example, APP engineers developed a number of applications in which extinguishing material is “pushed” out of a capsule in a dosed manner.

The latest APP innovation is again related to space travel: a parachute system for soft landing of the spacecraft that European Space Agency ESA wants to send to Mars in 2022. “The parachute is stowed in the capsule that holds the spacecraft. We make a kind of cannon that fires the parachute from the capsule.”


Space is the main focus of APP. “But space travel is getting more and more commercial, products are getting cheaper.” To be future-proof, Vermeulen hopes that the company will eventually achieve half of its turnover from products that have an industrial application. “Our advantage is that we have high-tech equipment here that not every company can afford, which we can also use for the development of industrial products.”


APP was founded by TNO (research organisation, ed.) in 1989 by TNO. A small division of machine manufacturer Stork, in collaboration with TNO, developed rocket igniters in Amsterdam, which were manufactured in Klundert. In 2005 the development was transferred from Amsterdam to Klundert. In 2018, the company was acquired by ArianeGroup, a partnership between aircraft manufacturer Airbus and French aerospace company Safran. APP has around fifty employees.

Note: This article was published originally in Dutch in BN De Stem, written by Ine Cup, 28-07-2020. Original article (in Dutch): https://www.bndestem.nl/moerdijk/klunderts-bedrijf-maakt-raketontstekers-als-countdown-bij-nul-is-zijn-wij-aan-de-beurt~ab60dfaf/

Header image (c) ArianeSpace

Website of Aerospace Propulsion Products (APP): https://app.ariane.group/en/

Remco Timmermans

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