Aircraft ultraviolet  protection, UV protection for your ultralight aircraft, ultra violet protection for ultralite aircraft.

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Underside of wing is bright the
way the fabric should be.

Top side of wing is faded indicating the fabric has suffered UV damage and is NOT airworthy!

Ultraviolet (UV) Protection for your amateur built, experimental and ultralight aircraft!
In the early days of ultralights, ultralight aircraft were no more than hang gliders with power packs. The little Mac 101, Chrysler Westbend, Pioneer chainsaw and little Solo engines lifted lightweight hang gliders into the air for short 15 minute interludes of flight.

These flights occurred early in the morning or late in the evening, just before dawn or dusk. The pilot would arrive at his chosen flying sight with his little glider all wrapped up in its bag. The assembly neatly tied to a one off designed roof rack, usually on top of a Volkswagen Beetle with 8 feet of bag hanging over front and back. Once the flight was over back into its bag the glider would go.

The average pilot would put in about 10 hours of flight in a year. This meant that his aircraft had a total of 10 hours of ultraviolet exposure in a year, all at times when the sun's rays were at their weakest.

Todays ultralights are considerably different than that of their predecessors. Today the craft are no longer folded down into bags, but are left out in the open, in farmers fields, or small open hangars.

In the fields they are exposed to UV light 8 to 12 hours a day 365 days of the year. If hangared or covered they are still exposed to UV when the craft is flown.

In training we average about 450 hours a year. This is logged hours using an hour meter on the engine. It does not consider the time the craft is left outside uncovered while we're talking to students, waiting for weather to clear, or having a bite to eat. Life expectancy for this fabric in these conditions in Canada has been shown to be about a year.

Pilots first noticed the fading when they compared the underside coloring of the wing to that of the top side. Since little was known about the life expectancy of the fabric, and no other signs were evident to warn the pilot of fabric weakening, many pilots just kept on flying their planes. Unaware of the potential for disaster.

On visiting a flying sight in Florida a friend asked me if I would like to fly his ultralight. The craft in question was less than a year old, but the fabric was badly faded on the top side. While doing a preflight I tripped and fell, in an attempt to prevent the fall, I grabbed the leading edge of the wing. MY FINGERS WENT RIGHT THROUGH THE FABRIC, In fact I able to run my baby finger along the fabric and tear it, with out any discomfort at all. In fact I able to run my baby finger along the fabric and tear it, with out any discomfort at all. In fact I able to run my baby finger along the fabric and tear it, with out any discomfort at all. In fact I able to run my baby finger along the fabric and tear it, with out any discomfort at all.

Later tests showed the fabric strength to be less than 15 lbs

According to sources in the industry this same dacron fabric when new, should test out at between 95 and 110 lbs.

Maule instrument test information indicates that a minimum of 46 lbs is the strength requirement for fabric on " light" aircraft.

Question: What product works?

Ladies and gentlemen, I am not a mechanical engineer, nor do I have an aeronautical engineering degree. The only way I have of knowing whether something works or doesn't work is to try it, or test it along side other products, or rely on information that I can obtain from people in the industry that I trust.

Another source of information that has proven invaluable is the Canadian Aviation Safety Board, and other government funded agencies.

In early 1984 an ultralight manufacturer that I deal with indicated that they had a product that they were trying in the hope of extending fabric life.

That product was Stits Aerothane A 100 101. In my opinion this product works, on dacron sail cloth to extend fabric life!

How do I know it works? By the only way I have available to me with my limited knowledge of these kinds of products. I have tried it! First on one of my own aircraft. This aircraft is now over 4 years old since coated, and has been left outside unprotected from the elements for 8 months each year since 1984.

The fabric on this plane has been tested 12 times to date, to 75 lbs using a Maule fabric tester, and at no time has the tester punctured the Stits coated dacron fabric. This fabric was finally replaced in 1992. While the fabric still tested good the threads holding the fabric together failed!

Another test that I did was to put 4 pieces of fabric out in the Florida sun on racks. Each piece of fabric was the same color, from the same bolt of material. Two pieces were covered in products advertised to prevent UV deterioration. One with Stits A0 100, the last left bare.

The only coating that stood the test of time was the Stits. In less than six months, (in Florida) the bare fabric, and the two that were coated in other so called UV barriers tested to less than 25 lbs.

The last test I was able to do on the Stits coated panel was in February 1988 when the fabric tested to 53 lbs. (Since then my mother- in- law thinking it was scrap through the panel in the garbage, thus destroying my chances of a Pulitzer prize for R & D into the life expectancy of 3.9 oz dacron in the ultralight environment.)

Question: Where is this product obtainable?

Answer: The Stits coating can be obtained from most of the leading ultralight aircraft mail order houses.

Question: Can it be applied on older fabric and still work?

Answer: Yes if the fabric in question still tests to a limit that you in your own mind would be happy with then it can be applied, and should maintain the fabric in that state for considerably longer than if it weren't protected.

Question: How much does it cost?

Answer: That depends on how much of your aircraft you are going to cover and how many coats you apply. Many owners only do the top surfaces of the wing, and tail section on aircraft like the MX.

Other owners flying Buccaneers with double surfaced wings and fuselage do the entire aircraft, including wings (upper and lower) body sock, and tail surfaces.

The cost for an MX style aircraft, to put on FOUR , good coats is about $250.00 US.

The cost for aircraft with double surfaced wings and enclosed dacron covered enclosures is about $500 US.

Question: What equipment do I need to apply the coating?

Answer: This product can be applied several ways, by brush, by roller, or by spraying it on.

The system I use and have had good results with is the spray on technique. It does require that the person applying the product have some knowledge of proper spray techniques, and application.

The other two systems do work but are not as professional looking when the job is finished. A good spray job looks as if it has another layer of clear fabric, right on top of the dacron.

Question: Are there any secrets, or hints for the first time user?

Answer: Yes! Use as little air pressure as possible when spraying, do all spraying in a well ventilated area, wear protective clothing, including overalls, gloves, and breathing apparatus.


Ensure that the area you are using is free of dust, otherwise the dust will show up in the finish in when it dries.

When applying give the whole craft a good tack coat, and wait about 20 minutes between coats. Mix only the amount of material required (it is a two part process) at one time, and to the specifications recommended by the manufacturer. Temperature plays an important role in the application and drying process so make sure that these recommendations are followed.

This information is available in the Stits Poly Fibre Aircraft Coatings Catalog #300, and can also be found on the instruction side of the AO100 can.

Also make sure to have on hand the proper thinning agents (if required), and cleaning solvents. A0100 hardens very quickly in the spray gun. We destroyed several nozzles before reading the instructions and obtaining the proper cleaner.

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Question: Are there any draw backs to using this product.

Answer: Yes! First if you need to pull your battens out, or damage a wing in any way, it will cause cracking in the aerothane coating. This can be repaired by simply sanding with wet sandpaper and reapplying the coating.

If you have an aircraft that folds down into a bag, or one that you break apart for storage, remember all parts that have been sprayed can not be folded down, or taken apart!

Another draw back is WEIGHT, you might be applying as much as 25 lbs of aerothane to your craft depending on how much surface area you have.

Question: Are there any other advantages to using this coating, besides UV protection?

Answer: Yes! The product makes the craft easy to clean as grease and oil do not stick to it. Pilots have also reported an increase in cruise speeds, of up to 5 m.p.h. after Stits was applied.

Question: Can I still use A0100 if my craft has been covered with Armoral or AP 303.

Answer: I have successfully applied A0100 after a thorough cleaning with the recommended Stits cleaner, followed by a thorough washing with soap and water, followed by a good rinse in water.

Caution: One aircraft that we did that had been recently coated in AP303, Fish Eyed on us, even after doing all of the above.

We ended up having to sand the fabric down with wet sand paper and then reapplying A0100.

Footnote: Recently I have done some more testing on three other products that have been introduced to me as UV protectors that can be used on dacron.

These are Hipec Clear Coat with UV barrier, which FAILED the test. While the fabric still looked good it had no strength.

Silver Nitrate, this process must be done on conventional fabric like Stits, etc. It can also be done on Dacron but you will have to paint the fabric after you finish. This process DOES work in extending fabric life.

Exterior house paint, and primer- believe it or not this works, is affordable and easy to obtain. Exterior primer and house paint HAVE UV protection in them. In fact some paints are guaranteed for 20 years.

This is a whole other story! U.B. Judge

Maule gauge is used to test fabric strength.

Transport Canada Aviation Safety report: A/W 8707 scientifically backs field experience on fabric life expectancy and strength loss for unprotected dacron 3.9 oz. saying that fabric left out in the sun for 6 months looses over 85% of its strength.

Stits cat # 300 for specific information on product application, and necessary cleaning and thinning agents.

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