Comments on the subject of the "Recovery System"
Take the following thoughts and ideas simply as a further basis of discussion and form your own opinions.
1. Definitions
- Parachute - many of us use them while flying and they don't need further explanation.
- NOAH - our emergency exit help system which can lift the pilot up to the height of the canopy rim and make it easier to exit the glider in case of an impending crash. It often happens that a pilot, even with plenty of altitude, is either hindered or has insufficient strength to exit his glider.
- Total Rescue System - a large parachute is used to lower the glider in a particular position. The rate of descent is around 5 to 6 meters per second which means a hard impact with the ground which cannot be softened by the pilots legs. This means that, with cockpits built as they are today, the injury to the pilot will not be trivial. Because of this, a total recovery system can only be used with a very strong cockpit.
- Rocket Extraction System "SOTEIRA" - In this system, the pilot is pulled out of the cockpit by a rocket and descends with a parachute. This is also in the experimental stage.
- As a consequence of the latest findings in accident research with Safety Cockpits, this is actually not an active recovery system but in any case necessary in connection with a total recovery system. Our DG-800 can be delivered with a safety cockpit as an option.
2. Accident Analysis
In order to compare the different recovery systems, it is meaningful to divide the possible accidents in gliders into two categories:
(1) Accidents in which the pilot can still be active in affecting the outcome,
(2) Spontaneous accidents in which the pilot has no chance of changing the outcome.
Accidents of the first type include
- midairs,
- serious technical failure of the glider’s control systems and
- bending or breaking of the aircraft due to overload in heavy turbulence.
It should be taken into consideration at what height the accident happens.
- At heights greater than 1500 ft agl, the pilot has a good chance of exiting the aircraft with a conventional parachute. If, however, the glider is in a spiral dive, it can happen that even at higher altitudes, the pilot cannot exit the aircraft due to centrifugal force holding him in his seat in spite of a maximum effort to escape.
- At altitudes greater than 800 ft, the NOAH system offers a good chance to exit the aircraft with a parachute.
- At lower altitudes, only a total recovery system is feasible.
Accidents of the second type in which the pilot has no influence on the outcome include:
- all landing and outlanding accidents,
- winch or aerotow accidents in which the wing touches the ground resulting in a cartwheel crash,
- a wing touching a ground-based object during ridge soaring,
- all steep turns close to the ground,
- especially after turning final too late,
- premature termination of the tow at low altitude with an attempt to return to the airport,
- stalling in the mountains due to turbulence close to the ground,
- continuing flight in or into bad weather.
Every glider pilot knows, and the accident investigation by TUEV of the Rhineland has confirmed it, that the number of accidents in the second category far outweigh those in the first category.
In those accidents, in which the pilot can have no effect on the outcome after the beginning of the catastrophe, the pilots will not be helped by their parachute, or the NOAH, or the total recovery system. In all these cases, only a very strong cockpit offers any possibility to survive.
We can draw the following conclusion from this:
Only in a small number of accidents is a total recovery system the only possible system that would be of any help.
In most cases, a NOAH system would be of help if the pilot were able to have even a little influence on the outcome.
A good strong cockpit is always absolutely necessary especially in those accidents in which the pilot is helpless to change the outcome.
A total recovery system requires a strong cockpit in any case in order to withstand the forces of the landing impact.
3. Requirements for a Total Recovery System
The current view is that the installation of a total recovery system in sailplanes on the market today is impossible. The Streifeneder company in Grabenstetten/Germany has built a standard class "modified glider" with a total recovery system. The modification goes so far as to make the original cockpit area unrecognizable. The entire canopy cutout was changed, reinforcement for a safety cockpit that wasn’t available at the time, and the fuselage behind the cockpit cutout and strengthened for the safety system. Normally, a total recovery system is built into a fuselage that has been especially prepared for it at manufacture. It would, of course, be possible without much trouble to laminate the straps in and attach them to the shear tubes, but that does not in any way finish the job. In any case, such a "preparation for a total recovery system" should be built into any standard class ships which are now in the design stage.
4. Cost of a recovery System
In the calculation of the cost of a total recovery system, the following items need to be taken into account:
- the cost of the actual recovery system,
- the expense of modification of the tooling for an existing glider,
- the development and certification costs of the system,
- the periodic cost of inspection.
No one can tell what the final outcome will be, but it will be rather high!
In addition, the safety cockpit logically follows as necessary and gives considerable added safety for another Euro 3,000.
In contrast, the NOAH system costs about Euro 3,000 completely installed.
5. Ease of Installation of a Total Recovery System
A total recovery system is naturally rather large even when it is delivered in a vacuum packed form as it undoubtedly will be in the future. The only possible space for such a system is in the fuselage near the trailing edge of the wing. Today, the percentage of motor gliders being built is growing more and more and there is no room in them for a total recovery system. For motor glider pilots, there remains only the NOAH system.
Even the "SOTEIRA" rocket extraction system is too big in our opinion to be put in the baggage compartment of a motor glider.
In any case, the installation of such a system would be impossible in a DG-808B, as it is constructed now.
6. Danger of an Inadvertent Activation
Have you thought about it? An airbag shouldn’t deploy suddenly without reason. In the automobile industry the possibility for intensive practice tests of accidental deployment of airbags is much greater than in the glider manufacturing industry. Who should pay for the expensive testing? Fundamentally one should recognize that technical things can fail.
So? We now know, on the basis of an accidental test, that an accidental deployment of the NOAH system is more or less harmless and without sequel. That can not be said of the other rescue systems now under development.
7. Availability
The NOAH recovery system is already available from DG as well as the safety cockpit which belongs with it.
A short video clip in three degrees of quality can be downloaded here.
The NOAH system can also be installed in all DG single seaters. The total recovery system is ready now, too. Even after the development is finished, it will not be possible to install it in any existing gliders.
A few prototypes might be finished in the near future. For "normal" sailplane pilots, it will not be available in the foreseeable future. Furthermore the cost will be very high.
The SOTEIRA system will not be available even in the nearfuture.
A total recovery system for a glider will be a very expensive safety installation - more than 10.000 Euro.
It is not installable in most new gliders.
The NOAH system, on the other hand, offers a similar increase in safety and it is available now for delivery and installation. The safety cockpit offers the greatest increase in safety and will always belong in a later version of a total recovery system.
- friedel weber - 
translated by David Noyes, Ohio 