Mid-cockpit brace

This series of articles will attempt to explain why it is impossible to certify a G202:
The loads imposed by the JAR23 for a -10g aircraft with two pilots on board, with a test temperature of 72°C, create very high stress forces which tend to open the fuselage and separate the mid-cockpit brace from the fuselage sides.
The solution adopted by CAP Aviation for the CAP 222 is:
- new materials with better mechanical properties at high temperatures;
- fuselage spars all along the fuselage sides;
- new design of the mid-cockpit brace itself in order to optimize the load distribution;
- larger bonding surfaces supporting shear load rather than peel load.
This solution was successfully tested up to 17g with no damage and the new fuselage was validated for the certified aircraft.

Ailerons

CAP 222 ailerons are totally new. They use five hinges which transfer most of the bending loads to the wing rear spar. The advantages (compared with a three-hinge aileron) are:
• ailerons are much lighter stress
• stress supported by each hinge is smaller
• stress supported by rear spar and wing skin (buckling) is smaller
The new aileron design has been taken into account when redesigning the wing, and new ribs has been added in front if the hinges.

Seat dynamic tests

The first development tests took place on December 7, 2000 at TUV, in the presence of Martin Sperber (TUV) and a representative of Schroth (belts).

- 1st test: downwards: 19g at 34km/h in order to check the compression column (max permissible=680kg). The value obtained during the first test was 560kg., which proves the quality of the design concept by the Apex Aircraft engineers.

- 2nd test: forwards: 26g at 50km/h. in order to check the behavior of the belts, the displacement of the dummy head and the stress on the shoulder harnesses.

The test showed that the belts remained well in place and that the pilot's head did not come in contact with the joystick.

The tests were to finalize the choice of seat geometry and the harnesses of the certified plane. The certification tests will be held in the presence of DGAC early in 2001.

Flight & spines tests

The CAP 222 manufacturer's flight tests were completed at the end of 2000 by spin tests. Because of pour weather conditions in eastern France we moved our test team to Cordoba in southern Spain.

It was an opportunity to test the incredible range of the CAP 222 and to carry out a first with a competition aircraft: the direct flight from Darois to Cordoba took 5h20' at an average speed of 160knots.

In someways it is easier to conduct spin tests on a competition stunt flying aircraft than on a conventional private plane. In fact, because of the absence of flaps or retractable gear, there are fewer test configurations.

On the other hand, having to test six spin turns, positive and negative, coupled with different flight command positions or engine parameters, ended up creating a rather interesting matrix of spins.

Before analyzing the aircraft during numerous spins, we used a miniature digital camera which filmed towards the nose of the aircraft. The recorded images make it possible to see the exterior, of course, but also the instruments showing flight control, joystick and rudder bar positions.

Lightning protection

The general approach used to protect the structure of the Cap 222 is as follows:

· Exterior skin surfaces in critical lightning zones incorporate an expanded copper foil. The adequacy of the protection (or lack thereof) was established by conducting tests on samples (see pictures).

· All skin components are electrically bonded to each other and to internal conduction paths with the use of integral copper connection tangs. The adequacy of the connection tang was tested.

· An adequate lightning path was established, and bonding of this and other internal metallic components was designed to minimize pilot shock hazards.

· Other aspects of the design were verified by similarity with tried and tested designs.

As different regions of the aircraft are in different lightning attachment zones, then different lightning threats apply, and greater or lesser lightning protection need be applied accordingly. The test levels varied from sample to sample in accordance with the appropriate lightning zoning requirement.

The tests show that the tangs were each capable of carrying the current. Pictured is damage from the arc attachment. The acceptability of the damage to the airframe was assessed by CAP Aviation.