The Bettsometer is one of the most critical instruments in paragliding technical inspections. While the porosimeter measures the "breathing" (air permeability) of the fabric, the Bettsometer measures its mechanical strength—specifically, how easily the wing fabric might tear under load.
Here is a comprehensive overview of the Bettsometer and Porosimeter in English:
The Bettsometer: Fabric Strength Testing
1. How the Bettsometer Works
The device consists of a specifically calibrated spring and a needle. The testing process is as follows:
Insertion: The inspector carefully inserts the device's needle into the wing fabric (usually at the leading edge, where wear is most significant).
Loading: Through the spring mechanism, a specific force (weight) is applied to the fabric.
Observation: The inspector observes whether the fabric threads withstand this load or if the needle tears through the material.
2. Standards and Indicators
The load on a Bettsometer is measured in grams (or Newtons). International standards (such as DHV or EN) define the results as follows:
Load (Grams)StatusExplanation> 1000 gExcellentFabric is like new with high structural integrity.600 - 1000 gAcceptableFabric is used, but flight is still safe.< 600 gDangerousFabric is "burnt" (UV degraded). Flight is strictly prohibited.
Note: Some manufacturers set the minimum threshold at 800g depending on the fabric type (e.g., ultralight materials).
3. Why is this Device So Important?
The Bettsometer checks for the "invisible enemy"—Ultraviolet (UV) radiation.
UV Degradation: Prolonged sun exposure causes nylon fibers to break down structurally. A wing may look visually fine, but the fabric can become "brittle" like old paper.
Critical Situations: A wing might hold during steady flight but fail during a high-load maneuver (like a strong collapse or a spiral dive). "Burnt" fabric can literally rip apart in mid-air.
The Porosimeter: Air Permeability Testing
The Porosimeter is the primary diagnostic tool for a paraglider's "health." It checks the hermeticity—how well the fabric retains air inside the wing.
1. How the Porosimeter Works
A paraglider flies based on internal pressure. The nylon is coated with a specialized layer to make it airtight. Over time, this coating wears off.
The Process: The device is clamped onto the fabric. It creates a flow of air (typically 0.25 liters under 10 $hPa$ pressure) and measures the time in seconds required for that air to pass through the fabric.
2. Interpretation of Results (JDC Standard)
The more time (seconds) it takes for air to pass, the "fresher" the wing.
Time (Seconds)Wing ConditionRecommendation> 300 sIdeal (New)The wing is practically brand new.150 - 300 sVery GoodStandard used wing in good condition.50 - 150 sSatisfactorySignificantly worn, but still safe to fly.20 - 50 sCritical (Old)The wing is at the end of its life; frequent checks required.< 10-15 sUnusable (Danger)Flight is prohibited. The wing is technically "dead."
3. Why is Porosity Critical?
Deep Stall (Parachutage): Low pressure due to high porosity makes the wing prone to staying stuck above the pilot without moving forward.
Degraded Handling: The wing becomes "sluggish" and reacts slowly to pilot input.
Launch Difficulties: The wing becomes heavy to inflate because air escapes through the pores of the fabric.
Summary: The Instructor's Responsibility
Professional instructors must use both tools during annual inspections, when buying/selling used gear, or after incidents (like water landings).
The Bettsometer checks if the wing can withstand the load, while the Porosimeter checks if it will actually fly stably. Together, they provide a complete picture of equipment safety.