Depron RC Plane: Foam Specs, Glues and Building Steps
Depron is a brand of extruded polystyrene (XPS) foam sheet, sold in 3, 6 and 9 mm thicknesses, and one of the most popular materials for scratch-built RC planes. 6 mm sheets weigh roughly 230–250 g/m², are stiff, smooth and easy to cut, and glue well with foam-safe adhesives. It suits indoor flyers, profile 3D planes and scale-look park flyers; for crash-heavy flying, EPP is tougher. Below: sheet specs, glues, a build sequence and alternatives when you can’t get Depron.
By Kyle HilsonUpdated: October 20264 min read
What is Depron foam?
Depron is a closed-cell XPS foam sheet originally made in Germany for insulation, now widely sold for model building. Closed cells mean it doesn’t soak up water, has a smooth surface that takes paint, and can be bent over heat. It is brittle compared to EPP: it dents and snaps rather than bending back.
| Thickness | Approx. weight (g/m²) | Typical use |
|---|---|---|
| 3 mm | 90–150 | Indoor models, ribs, fins, light control surfaces |
| 6 mm | 230–250 | Profile 3D planes, park flyer wings and fuselages |
| 9 mm | heavier | Fuselage sides, larger models, laminated blocks |
Figures from model-shop listings; weight varies between batches and grades (an “Aero” grade is lighter). In the US, German Depron is imported in 3, 6 and 9 mm with sheets up to about 31.5 × 49.5 in.
Depron vs EPP vs foamboard vs balsa
| Material | Weight | Stiffness | Crash survival | Best for |
|---|---|---|---|---|
| Depron (XPS) | Light | Good | Fair: dents, snaps | Indoor and scale-look scratch builds |
| EPP | Light–medium | Low (needs carbon) | Excellent | 3D trainers, combat, learning |
| Foamboard (paper-faced) | About as heavy as 6 mm Depron | Good | Fair; paper delaminates when wet | Cheap scratch builds, hot glue |
| Balsa | Light per strength | Very good | Poor to fair | Classic and scale models |
XPS vs EPS: XPS (Depron, insulation sheets) has a smooth closed surface; EPS (bead foam, packaging) is lumpy, weaker and only good as a hot-wire core under a skin. Balsa building is in our balsa RC airplane guide.
Which glue works on Depron?
| Glue | Works? | Notes |
|---|---|---|
| UHU Por / foam contact glue | Yes | Apply to both sides, let it flash off, press together; flexible joint |
| Foam-safe CA (odourless) + kicker | Yes | Fast, hard joint |
| Hot glue (low temperature) | Yes, carefully | A hot gun melts thin Depron; heavier joint |
| Epoxy | Yes | For carbon spars, motor mounts, hard points |
| Normal CA, solvent glues, spray adhesive with solvents | No | Melts polystyrene |
Test any glue and paint on a scrap piece first. Water-based acrylic paint is safe; many solvent spray paints eat XPS.
How to build a Depron plane
- Print the plans at full scale and fix them on the sheet with low-tack spray or tape.
- Cut with a new snap-off blade, several light passes along a steel ruler. Change blades often; dull blades tear foam.
- Sand edges with fine paper on a block. Bevel hinge lines at 45°.
- Stiffen: glue a carbon strip or rod into a slot along the wing and fuselage. Depron profile planes flutter and flex without it.
- Bend curves by warming the foam with a heat gun on low and shaping it over a form, or score one side.
- Hard points: plywood or carbon plates for motor mount and landing gear, glued with epoxy.
- Hinges and linkages: tape hinges, carbon or steel pushrods, horns glued through the surface.
- Finish: acrylic paint or laminating film applied with a low-heat iron; balance at the plan’s CG.
Motor and battery selection follows the same steps as for any electric plane: sizing an electric motor.
What if I can’t get Depron?
- Paper-faced foamboard (e.g. dollar-store foam board): cheap, hot-glue friendly; peel the paper for lighter parts.
- XPS insulation sheets from building suppliers: often thicker and heavier, but usable when sliced or for fuselages.
- Foam ceiling tiles / “Depron-like” sheets sold for picture framing or packaging: check density and that the surface is closed-cell.
- EPP sheets when crash resistance matters more than stiffness.
FAQ
What is close to Depron foam for RC planes?
Thin XPS sheets sold as insulation or for model making, and paper-faced foamboard. Both are XPS-like closed-cell foam; check weight per square metre.
Which foam board can be glued with hot glue?
Paper-faced foamboard takes hot glue well. On bare Depron use a low-temperature glue gun, or the foam melts.
XPS or EPS for building RC planes?
XPS for sheet-built planes: stronger, smoother and closed-cell. EPS only as a hot-wire-cut core covered with a skin.
Can I use heat shrink film on foam?
Yes, with low-temperature laminating or covering film and the iron at its lowest setting; too much heat melts the foam.
More on this topic: the complete RC Airplanes guide covers the basics behind this article.
About 20 years in RC. Mostly boats in the NAVIGA Mini Eco Expert class, with many self-made parts; also a King Motor Baja 5B, a home-built electric plane, home-built nitro planes he has flown, and an RC helicopter. More about SwellRC
