For a long time, if we wanted to build a lightweight electric parkfly model we reached for the Depron. Now we have this “foam board” to consider…
When I first saw foam board being used to build models I was confused. Was it just a different type of Depron? Of course, over in the states I was watching videos of models built from foam board that were crash resistant and flew great – and it only cost around a dollar a sheet!
So, I went searching online for foam board and found suppliers in Sydney that would post me packs of the stuff for around $10 a sheet. This seemed a bit steep but then this is Australia and those import taxes are a killer. I was almost ready to place an order when I read this on the Flite Test site – http://flitetest.com/articles/foamboard-in-australia.
Confused, I decided to just buy some sheet of different building materials and try it out for myself in a Depron vs Foam Board building frenzy…
Depron is a foam sheeting normally used for things like underfloor heating but found fame some time ago when it was introduced to the indoor flying scene by the Icarus Shockflyer range. Depron has an excellent strength to weight ratio and, if braced properly, produces some amazing models from tiny indoor flyers to massive scale jets. In fact, in recent years there have been more giant scale models built from Depron as its can be used to build incredibly lightly meaning giant scale models are easier to power, fly and produce a better scale speed in the air.
I bought a pack of 10 sheets of 6mm white Depron from Tradewarehouse (http://www.tradewarehouse.com.au/more/depron-foam.html). The total cost came in at around $9.20 per sheet of 100cm x 35cm, so not cheap by any account.
Depron is easy to work with. It can be cold formed by rolling it over the table edge and cut easily with a scalpel type blade. You have to take care when gluing Depron as anything with a solvent in it will melt the foam. Even hot glue can be a problem when it gets really hot.
I quickly put together a FT Flyer to try it out. The resulting model was exceptionally light, being overpowered with a Park 250 motor and 2 cell lipo. The shiny surface of the foam gives a nice finish although it is nearly impossible to paint or even adhere decals to.
On the downside is the fragility of the material. I had to remake several parts during the built as the thinner parts simply snapped and I am sure one crash will be the end of the model.
I tried two different types of 5mm foam board:
Quill from Officeworks – $10.50 for a 50cm x 77cm sheet is a bit steep but it does come in a variety of colours. The paper coating is a very thick clay paper and I was concerned that it felt very heavy.
Riot Art & Craft – A variety of size board available in black and white here. I went for two sizes – 59cm x 84cm for $9.99 and 100cm x 80cm for $14.99. Whilst still expensive these sheets are both larger than the Quill board and seem to be lighter as well.
The first model I built was a FT Bloody Wonder using the Quill board. This was harder to cut than Depron but I really liked the positive, smooth action the blade takes through the foam. Very easy to build with hot glue and certainly more resistant to damage than Depron. The finished model however felt heavy and I was convinced it would never fly. Amazingly though I was proved very wrong and the model flies beautifully…
The second model built was the FT Versa Wing using the Riot board. This was built as a slope model so I wasn’t as concerned about the weight. This foam does indeed seem to have a thinner paper coating and is easier to crease and bend. The finished model felt lighter than the Bloody Wonder and test throws at the field showed a promising glide.
It tends to be a little breezy in this part of Australia and Depron models don’t cope well in anything more than a couple of km/hr. For this reason, the increased weight of foam board is actually a benefit as it produces a model that is more able to cope with the wind. Add to that the resilience of foam board and ease of construction using a simple hot-glue gun and you have a winning formula.
Depron will always have a place in our hearts for more complex internal structures and models where extremely light weight is required but the fragility of the material is, and will continue to be a problem.