posted Feb 4th, 2009 - Dr. Ulrich "Uli" Sehrbrock has been a member of several German national 8-way lineups, mostly with his FSC Remscheid skydiving club, for many years. He is one of the longest standing and most passionate Formation Skydiving competitors in the sport. He has recently switched back to his favorite event, 4-way competition, where he has been training and competing with his new X-Ray Remscheid lineup since the beginning of the 2008 season.

The new X-Ray Remscheid lineup with, Uli Sehrbrock in the Center Outside slot, managed to put some heat on Germany's reigning 4-way champions of FSC Eisenach last year and challenged the national champions seriously at the DFV Cup 2008. X-Ray is already in full training swing for the 2009 season and plans to push even harder for the top spot in Germany's 4-way rankings.

Uli Sehrbrock is an engineer in his other life and has been running his own engineering firm in Braunschweig successfully for many years. He is also teaching randomly at the University of Braunschweig. This connection began to move into a new direction when the passionate 4-way competitor and canopy pilot thought about a new way how to use sophisticated engineering technology in his skydiving environment.

Result of many meetings, discussions, thoughts and experiments was a program that he called "CATE", the Canopy Test Equipment. He began with the development of the necessary hardware and software and found support by a company in Braunschweig, the messWERK GmbH, which worked in the same engineering direction.

The efforts by the small group have recently been supported by another experienced German skydiver and former 4-way competitor, Pitt Weber, who trained and competed with the German national team of many years, Daedalus. Pitt Weber is one of the most experienced riggers and equipment experts in Germany and became interested in Uli Sehrbrock's CATE project.

Eventually, the first results of the project have now become tangible, and the German skydiving federation (DFV) has officially begun with a promising cooperation. Last month's issue of the German skydiving magazine "Freifall Xpress" published the story of the project. Goal is to publish the first official test results of different parachutes soon and on a regular basis. Dr. Ulrich Sehrbrock provided the NSL News with a description of CATE:

Driving test for parachutes?

Who would buy a computer these days without getting information of its capabilities? Nobody... Who would buy a car without checking the relevant data of driving tests? Nobody, of course... And who buys parachutes to save lives without knowing much about the flight characteristics? The whole skydiving community...

Alright, this was admittingly a provocative introduction. Of course, we try to inform ourselves as much as possible before we buy our next parachute. However, there is still a lot of truth about the lack of hard data that we have available. Our decision is mostly based on guesses, estimations and feelings, like: flies really well, very agile, aggressive, flares nicely, opens softly/hard openings, feels like a lame duck, etc.

These general descriptions have been working okay since we all eventually adjust to the flight characteristics of our new parachute after the purchase. We have to. Rate of descent and/or travel speed don’t seem to be so very important any longer. You may be unhappy once in a while when you could not make it back to the landing area while others did. Despite the lack of availability of hard data we still love to discuss the behavior of our parachutes since we grow very close to them.

For instance, I found it very impressive to find out that I was traveling with an air speed of 60 km/h after opening with unreleased breaks. Okay, I am flying a 97 sq.ft. parachute, however, it still seemed faster than I thought. The air speed went up to even 80 km/h after releasing the breaks. So I switched to a more popular 120 sq.ft. canopy, and the air speed was still at remarkable 50 km/h in breaks and 65 km/h after releasing the breaks. And I am surely not a heavyweight... The 1 : 2 rate of descent (1 meter descent and 2 meters distance) was significantly steeper than I ever thought.

This data (see charts above) was collected when I made some test jumps with equipment that was specifically developed to measure the flight characteristics of parachutes. The German „messWERK GmbH“ built this equipment to collect in-flight data for aerobatics. I used the first prototype of the equipment for my own test flights.

Next step is to optimize the hardware as of setup, size, weight and general handling. Other helpful components, such as measuring devices for steering direction and steering effort, will be added during this phase. At the same time, the software program that evaluates and visualizes the data will be specified and modified to accommodate the testing of parachutes.

This equipment will allow to measure not only speed and rate of descent but also speed and degrees of turns, the swinging momentum of the jumper under the parachute in all directions and any forces during turns, which can easily exceed 2 g. The opening of the parachute is a part of this measuring, as well. The complete system is called „CATE“ (Canopy Test Equipment), and it will accurately measure all flight characteristics plus opening behavior and provide hard data for objective evaluation. The data will also allow to compare different parachutes directly with each other. It will help to know your own equipment much better, which is a nice side effect.

Plan is to test many more different parachutes this year and publish the results in the skydiving media. We will try to always test two different parachutes and publish the results parallel with each other. The tests are not limited to main parachutes. There is very little knowledge and experience available how reserve parachutes actually perform, and they will be included in the tests. The produced data will provide information of:

- Air speed (in breaks and released) - Rate of Descent - Gliding angle - Stalling speed - Turning speed - Descent rate during turns - Acceleration during turns - Stabilizing after turns - Flaring behavior

That’s the plan that we would like to introduce at the moment. We hope that the skydiving community has enough interest to support this project („Driving Test for Parachutes“).

We need your feedback, and we need financial support since the development of the technology and the actual tests of the parachutes costs money. It is our goal to produce new data and information and publish it on a regular basis. The German skydiving federation already supports the project with technical information and sanctioning. However, the financial burden is still on the shoulders of the creators so far.

Uli Sehrbrock / Harry Kloska / Pitt Weber