PETG vs ABS vs ASA for Outdoor Drone Parts: UV and Impact Resistance
3D printed drone parts live a hard life. An antenna mount baking in direct sunlight on a 35°C day. A GoPro TPU bumper taking repeated 80km/h impacts into tree branches. A GPS mast vibrating at 200Hz for hours of flight time. Pick the wrong filament and your part fails — sometimes mid-flight, with expensive consequences. Here’s what actually holds up outdoors versus what the spec sheets promise.
The Contenders
PETG is the easy one. It prints at 230-250°C on any printer with a PTFE-lined hotend, doesn’t require an enclosure, and costs $15-25 per kg. It’s the default “outdoor” filament for most hobbyists because it bridges the gap between PLA’s printability and ABS’s durability.
ABS is the old-school engineering plastic. It’s tougher than PETG, handles higher temperatures (glass transition at ~105°C vs PETG’s ~80°C), and can be vapor-smoothed with acetone for a professional finish. But it warps like crazy without an enclosure, stinks of styrene during printing, and requires a bed temperature of 100-110°C.
ASA is ABS’s outdoor-optimized cousin. The chemical structure is nearly identical, but ASA replaces the butadiene rubber in ABS with acrylate rubber — making it dramatically more UV-resistant. It prints at similar temperatures, warps similarly, and costs slightly more ($25-40/kg). For anything that lives outside, ASA is what ABS wishes it was.
UV Resistance: What the Sun Actually Does
UV radiation breaks polymer chains. The damage is cumulative and irreversible. After 6-12 months of outdoor exposure:
- PLA: Becomes brittle and crumbles. Color fades severely. Structural failure within 3-6 months of direct sun. Never use PLA for outdoor drone parts.
- PETG: Moderate UV resistance. Color stays reasonably stable. Mechanical properties degrade slowly — expect 20-30% loss in impact strength after 12 months outdoors. Still flyable but replacement recommended annually.
- ABS: Poor UV resistance unless UV-stabilized. Turns chalky and yellow. Impact strength drops 40-60% after 12 months. The butadiene component is the weak link — UV attacks it aggressively.
- ASA: Excellent UV resistance — this is literally what it was designed for. Used in automotive exterior trim, boat parts, and outdoor signage. Less than 10% mechanical degradation after 2+ years outdoors. Color holds well.
For a drone that flies a few hours a week and lives in a bag the rest of the time, PETG is fine. For a drone that lives on a shelf in direct window light, or for permanent outdoor installations (antenna mounts, weather station brackets), ASA is the only choice.
Impact Resistance: Surviving the Crash
Falling from 50 meters onto concrete is the ultimate material test. Here’s how they rank, based on Izod impact testing and real crash data:
| Material | Izod Impact (J/m) | Failure Mode | Crash Survivability |
|---|---|---|---|
| TPU (95A) | No break | Elastic deformation | Excellent — bounces |
| PETG | 80-100 | Ductile — bends before breaking | Good — deforms but stays intact |
| ASA | 150-250 | Ductile — bends significantly | Very good — absorbs energy well |
| ABS | 200-300 | Ductile to brittle (depends on print quality) | Good if printed well, shatters if layer adhesion is poor |
| PLA | 20-30 | Brittle — shatters | Poor — explodes on impact |
The key takeaway: PETG, ABS, and ASA all survive crashes well when printed correctly. Layer adhesion is the real differentiator. A poorly printed ABS part with weak layer bonding will shatter faster than a well-printed PETG part. Print temperature, cooling, and enclosure temperature matter more than the filament itself.
Temperature Performance: When Heat Becomes the Problem
Motor mounts, VTX brackets, and flight controller standoffs get hot. Here’s the glass transition temperature (Tg) for each — the point where the material softens and loses structural integrity:
- PETG: Tg ~80°C. Softens noticeably at 70°C. Don’t use for direct motor mounts on high-power builds. Fine for antenna mounts, GPS masts, and GoPro cages.
- ABS: Tg ~105°C. Can handle motor mount heat (motors rarely exceed 90°C at the base). Good for anything on the frame.
- ASA: Tg ~105°C. Same as ABS. The outdoor version of ABS with identical thermal performance.
For reference, TPU (the soft flexible filament used for camera mounts and landing pads) has a Tg of around -20°C to 40°C depending on hardness, but TPU doesn’t fail catastrophically when it softens — it just gets more flexible. That’s actually desirable for vibration-damping parts.
Practical Recommendations for Drone Parts
| Part Type | Recommended Material | Why |
|---|---|---|
| Antenna mount (external) | ASA or PETG | UV exposure + moderate impact risk |
| GoPro / camera mount | TPU (95A) | Vibration damping + impact absorption |
| GPS mast / holder | PETG | Low stress, good enough UV resistance |
| Motor wire protector / arm guard | TPU or ASA | Impact resistance critical |
| FC/ESC stack spacers | PETG or ABS | Heat exposure from ESC; avoid PLA |
| Landing skids | TPU | Compression + impact |
| Frame components (experimental) | ASA or PC Blend | Maximum durability required |
| Permanent outdoor installations | ASA | UV + weather resistance non-negotiable |
If you only stock two filaments for drone parts, make them TPU (95A) and PETG. TPU handles anything that needs to flex or absorb shock. PETG handles everything structural while being easy to print. Add ASA when you have an enclosure and need outdoor longevity. Skip ABS entirely — ASA does everything ABS does, but better outdoors, and the price difference is negligible for the quantities used in drone parts.