The Aquilo III.V is the love child of explosions and improvements.
The 3rd rocket in the project was tragically lost on launch. The team analysed what happened and improved the rocket.
The Aquilo III.V was developed at the same time as the Aquilo IV. Two teams worked simultaneously on the two rockets. In the bottom-right picture, the Aquilo III.V and IV can be seen next to one another.
The improvements made on the Aquilo III proved to be successful. Launching the rocket no longer let to any engine problems. However, the overall launch was not successful. There was a launch lug failure, this leads to a change in the rocket's trajection. This made the rocket go ballistic and the parachute was deployed too soon. The failure resulted in a semi-horizontal flight path. The opening of the parachute happened too early at a too high speed and the cord of the parachute ruptured the body tubes.
The two pictures above show the rocket leaving the launch pad in an uncontrolled direction.
The Aquilo 3.5 utilizes the same PB51 engine as the Aquilo III.
Launch lug failure
From left to right, the team that made the Aquilo III.V rocket: Daan Bank, Tommy Borsboom, Martin Kampinga, Leo Deelman and Thomas Dumoulin.