Here is some clarification on DULV paraglider testing.
First, tests are flown using a paramotor as opposed to free flight
without a motor. They are flown at the
wing makers listed maximum take-off weight and include tests with trimmers closed and open if the glider is equipped with trimmers.
We are checking to see if they do tests with speedbar on those gliders so
equipped.
Here are some aspects of the DULV testing. Remember, this is only
required in Germany but the testing can provide valuable information to
wing buyers.
1. The glider must have a minimum wing load of 9.9 lbs/m² (4.5 kg) to be
considered a motor glider, otherwise it's a motor-assisted
paraglider (like a powered sailplane). In Germany, motor wings with a lighter
loading must have both and DHV certification.
The philosophy is that a smaller glider is more stable, faster and has less
tendency to negative spin (a Cessna doesn't have wings like a glider).
2. Load test to insure the glider is structurally able to handle the extra
load imposed by heavier weights typical of their use.
3. Maneuvers have been adapted especially to the paramotoring purpose.
Here is some of what is tested by the DULV. Some of the highly dynamic tests
are flown in free flight for test-pilot safety.
- launching behavior
- level flight with no oscillation allowed (see sidebar
on this, though)
- multiple turnarounds / sharp turns. (no collapse
allowed; must not have any tendency to negative spin).
- flying under full power (must not have any tendency to deepstall or full
stall; brake travel has to be long enough to do a turn against the torque
effect).
- Pulling brakes until glider wants to enter the full stall (glider must
signal the full stall, have progressive brake pressure and sufficient brake
travel).
- front stall in the worst condition - no thrust.
- one side collapse in the worst condition - no thrust.
- spiral dive (glider must not accelerate).
- full throttle - idle - full throttle - idle (no front stall or collapse
allowed).
- landing behavior.
4. main difference between DULV Standard and DULV Advanced is that, if you
want to gain the Standard certificate, the glider has to recover on its own without active piloting.
The Naja is the first (and only as of 9/14/2007) wing to be certified
advanced.
Difference From DHV
The DHV tests wings only using a standard harness with set riser
spread. DULV tests wings in combination with a motor as a set and tests to
see that a wing is generally suitable for paramotoring. In Germany, the glider has to be tested with every
single engine, a process simplified by doing only a conformity check
flight. The merely insures that the wing has no unusual behaviors
when flown with that particular motor.
So a complete test is flown under one motor and a comformity test flown
with other motors that want to be certified with that wing. That is
probably where the misconception comes from about DULV only doing one
flight with a motor. |
Jason Shapiro flying along
with an induced 50% collapse.
Motor-wing Oscillation
Some wings, when combined with
some motors, will oscillate. You swing back and forth in shallow little
banks with no pilot input.
It is caused by the motor
twisting slightly at the end of an oscillation. The thrustline turns to
point the other way and pushes in the other direction, causing it to worsen
slowly.
I see this behavior in about
5% of the wings I try and it has never been more than annoying for hands-off
cruising.
Another pilot, on a different
motor (even the same brand), may not experience the tendency.
If your motor twists when the
risers are lifted unevenly than it is subject to having this happen. |
