Background:
In 1991 US military was brought to a point of reality when previous mission planners were not fully prepared for desert operations. When the military began operations under desert conditions, they immediately discovered that critical equipment didn’t last long. It became evident that military hardware and commercially manufactured items, optics, navigation systems, instrumentation computers, etc., began to fail due to the extreme desert environment.

Testing standards with too much variance:
To prepare for these conditions, the test community had limited resources to perform reliable and repeatable tests with sand and dust. This is evident if you look at the mil standard of MIL-STD-810G method 5.10.4.

That current standard has a concentration tolerance of plus or minus 70% under specific test protocols. To put this into perspective, compare this to the MIL-STD-810G for temperature which is +/- 2 degrees Celsius. This equates to a tolerance of 1%. This wide variance in concentration is allowance for test chambers previously available to the test community. Compared to other environmental tests, they are within a few percentage points of the minimum or maximum parameter setpoint. Less variance translates into a more repeatable test. Now we can plot a trend analysis and predict how long equipment will last in a particular desert environment. We can maintain this accuracy with many types of test media including volcanic ash, planetary crustal dust and cosmic dust.

How items should be tested:
Testing a commercial, military or space vehicle/craft, we need to replicate the conditions that nature produces during the sand and dust storm or space travel with one exception – nature produces constantly varied temperature, pressure, particle concentration and wind velocity. In a laboratory environment, a continuously variable test, results in unpredictability for any item subjected to the environmental test.

We want to remove all the variables for a constant state of sand or dust concentration – for wind velocity, temperature, and humidity.

Now we have an environment with constants that we can subject a part or piece of equipment and conduct multiple tests for specimens such as a shoulder weapon, handheld computer system or avionics. If we can produce a failure during the test, and do it in “X” number of minutes, and repeat that again, and a third time…we just plotted the mean time between failures under those very precise conditions.

How desert condition testing was conducted in the Lab and the Military:
Many desert simulations were done using a cobbled together piece of equipment brought into a lab environment (a few major aerospace companies currently have dust chambers made of plywood!).

The tests were performed through a combination of widely varying equipment configurations. Commercial labs would announce their capabilities to perform accurate tests while meeting the standards. The labs tested and usually passed items, only to later fail under field trials. Of course the tests were and still are very low cost, while using patched together chambers using technology suggested in the MIL-STD-810. This type of test is usually accompanied by a hand written checklist as verification that all went well during the test.

Frustrated with the lab results and determined (at a high cost) to test mission critical components, the problem remained. The logical approach, while resource intensive, placed the specimen under real life field conditions.

Several routine approaches were used to ensure specimens were field-ready:

• By simulating a war-game under desert conditions
• By strapping a component onto the front of a hum-vee and drive around in a single file convoy for a period of time
• Employ low flying rotorcraft as a means to generate high particle concentrations and high velocities while following closely behind in a hum-vee where the specimen was strapped to the front of the vehicle.

Again, this produced widely variable test conditions, a cluster bomb approach.

New technology with precise control of variables:
The Desert WindTM system is a compilation of scientific grade equipment that utilizes precision equipment that delivers accurate concentrations of sand or dust using “mass-over-time methodology”. The system provides stable particle concentration, temperature, humidity and velocity. The Desert WindTM technology removes the variables found in nature, hobbled together test chambers and simulated field operations to +/- 5% and below.

Typical laboratory test equipment is constructed using commercial grade enclosures and components. The sand and dust test process requires heavy duty industrial construction using manufacturing process equipment components along with the most powerful industrial microprocessor to accomplish the testing.

Where to go to get items tested:
If you are in the US military or a NATO approved entity, the Naval Air Warfare Center will test specimens for a fee. They have a Desert WindTM system installed in their facility. They explain the systems capability as “the most sophisticated environmental test chamber in the world”

Website: http://www.navair.navy.mil/nawcad/index.cfm

The Center for Aerospace Technology in Canada will test commercialized items. They are ISO 17025 certified and will provide documentable system of protocol for testing for guaranteed repeatability in the test protocol process.

Stéphane Carpentier
Directeur Innovation & développement / Manager Innovation & Development
stephane.carpentier@college-em.qc.ca

CTA – Centre technologique en aérospatiale
5555, place de la Savane,
St-Hubert (Qc) Canada J3Y 8Y9
Tél. /Tel.: (450) 678-2001 p./ext.: 4553
Téléc. /Fax: (450) 678-1702 * www.aerospatiale.org

Items for testing in desert conditions:
Here is a sample of the requests for items to be tested in the Desert Wind environmental test chamber:

• Sidearms and shoulder arms
  Land based TOE missile (surface to surface) surface to air missile, War fighter personal computer, GPS equipment.
• Appurtenances on a land based vehicle or aircraft
• Any part or component on an aircraft for wear abrasion or intrusion while ground based (rotary or fixed wing)
• Cockpit or canopy, FLIR lens
• Aerospace coatings
• Gun turrets

Final note:
We want to test under the most rigid conditions to have the equipment perform as expected – this brings people home alive…

Dan Lehman
President
Air Dynamics
dlehman@airdynamics.net
717-854-4050
www.airdynamics.net