ALL ABOUT EPP FOAM.... and why it is important to you....
The foam fairly closely resembles regular white "styrofoam" (expanded polystyrene, EPS) in appearance and weight but is blessed with very different structural characteristics. When stressed, rather than denting, creasing or cracking like polystyrene, EPP foam flexes, absorbs the stresses and springs back to its original shape.
When used in combination with fibreglass reinforced strapping tape for added tensile strength and a spar system for in-flight rigidity, RC model aircraft made using EPP foam our rendered almost unbreakable. They're able to withstand high speed mid-air collisions with other models and also have an uncanny habit of emerging unscathed from spectacular impacts with fixed solid objects such as trees, fence posts, rock walls and, of course, the ground!
Although not recommended, you can literally jump on an EPP wing while it's lying flat on the ground without causing damage. In fact, Kye has personally witnessed a RC glider made from EPP crash onto a bitumen road then get run over by several cars before being retrieved, given a quick check over on the walk back to the edge of the slope and simply re-launched! Amazingly, thanks to the incredible durability of EPP foam, the glider suffered only superficial grazes to its covering.
EPP foam was first used for making RC model gliders in 1995 by Pat Bowman in the USA. In the following e-mail, dated 22nd October 2003, Pat kindly agreed to provide us with a first-hand personal account of how it all began:
"Hi Kaylet, Yes I was the first person to build gliders out of EPP. I worked at a company that had many government contracts for the Navy. They manufactured and repaired dehydration and high pressure systems for battle ships and submarines. I ran the shipping and packaging department plus I was the packaging specialist for all government contracts. In each government contract there are packaging codes to tell you how each part should be preserved, cushioned and boxed.
My job was to work out the codes and buy the materials used to package the parts. On one job the call out was for EPP foam for cushioning, when I received the foam I noticed that it had total memory when hit on a table and would bounce when thrown on the ground, plus it was very dense and strong. I thought to my self, I wonder if I can wire cut this, so I took some scrap home and tried the wire cut on it. It worked fine so I bought some for myself and made the first EPP foam plane called the Ruffneck.
I took the plane to my local hill and tried it out, it worked great, I crashed many, many times and all it did was bounce with no damage. At the time we were making planes out of white foam and covering them with tape for combat, they lasted longer than balsa planes but the foam turned to beads after a while. I fly with Joe Wurts all the time and was supplying him with combat planes.
He called me one evening and said that he was going to New Zealand to fly combat with the guys over there and needed a new plane to take with him. I told him that I did not have any kits available but that I had this new plane made out of EPP foam and was extremely durable. I took it over to him and showed him it and he was very excided about it. I told him that he could take it with him to New Zealand and try it out.
In New Zealand they were still flying the white foam planes so when Joe combated with them he almost destroyed every one of their planes. When he got back he wrote an article in a magazine about his trip to New Zealand and mentioned about the new EPP plane and how durable it was and the rest is history. I still have that same plane today.
I started manufacturing the Ruffneck in 1995, needless to say I could not make them fast enough. At the time there were two other slope manufacturers in business, Dave's Aircraft works and Trick RC. Dave was making small scale balsa planes and Trick was making his Zagi with white foam. When they heard about my discovery (EPP foam) they were beating my door down to find out where to get it. After me, Dave was the next to come out with an EPP plane then Trick started making his Zagi out of EPP, then Studio B. Since then there are many other EPP manufacturers out there..."
EPP foam's incredible durability has had, and continues to have, a huge impact on RC gliding. The initiation into the hobby used to entail several weeks devoted to building up a RC glider from a box full of a few dozen bits and pieces, crashing within a few seconds of its maiden flight, picking up the remains in a few dozen bits and pieces then spending another several weeks repairing or building a new glider before trying again.
Newcomers were required to persevere through several of these cycles before they managed to accumulate enough air-time for them to have learned the basic flying skills. Needless to say, most gave up, and the few of us that made it through had an understandable tendency to be very timid and hesitant flyers, but were great at repairs!
The advent of RC gliders made from foam, particularly EPP foam, dramatically changed the learning process. While crashes are of course still inevitable, instead of picking up their glider in pieces after a crash, beginners can now simply re-launch and try again - learning a little from each mistake along the way. This has effectively cut the time required to learn the basic skills needed to keep a RC glider in the air from a few months down to a few hours and, most importantly, the whole process is now a lot more enjoyable!
Perhaps of even greater importance is the marked change in the way that more experienced RC pilots now fly their models. EPP foam has had a truly liberating effect. Flyers can now much more easily extend their capabilities by practicing new aerobatic manoeuvres, high speed "dynamic soaring", low passes, touch-and-goes etc. and take part in full contact aerial combat sessions without the worry of destroying their model when it crashes. And of course, if you do manage to damage an EPP glider, they're usually easy to repair and relatively cheap to replace.
The changes that EPP foam has brought to the hobby of RC gliding, slope soaring in particular, are responsible for its recent rapid growth in popularity. It has made the hobby much more accessible to many more people and the style of flying much more appealing to a younger generation, and the young at heart! Basically, EPP foam has injected RC slope soaring with a huge dose of FUN and ACTION, with the activity increasingly becoming less like a hobby and much more like a sport.
Courtesy of Kye at Wowings.com