When I first unlocked yellow science, I thought I was almost done. Then I looked at the recipe: one flying robot frame (which needs electric engines, batteries, and green circuits), one processing unit (which needs its entire assembly line), and speed modules (which need red circuits and sulfur). I needed a new factory for each ingredient. This is the setup that got me through it.
Recipe Breakdown
Utility science pack takes three components, each with its own deep production chain:
| Ingredient | Sub-components | Difficulty level |
|---|---|---|
| Flying robot frame | Electric engine (2x engine + lubricant), battery (sulfuric acid + iron), green circuit (2x copper + iron), steel | Hard |
| Processing unit (blue chip) | Red circuit (plastic + green + copper), green circuit, sulfuric acid | Hardest |
| Speed module | Red circuit (plastic + green + copper), sulfur (petroleum + water) | Medium |
Processing units are the hardest ingredient in yellow science. They need sulfuric acid (which means sulfur and water), and each one consumes 2 red circuits + 20 green circuits. That's a serious load on your existing circuit production.
Optimal Ratio for 5 SPM
| Component | Machines | Notes |
|---|---|---|
| Yellow science assemblers | 8 | Target output |
| Flying robot frame assemblers | 2 | Each feeds ~4 science assemblers |
| Processing unit assemblers | 1 | One feeds ~10 science assemblers |
| Speed module 1 assemblers | 2 | Each feeds ~4 science assemblers |
| Battery chemical plants | 1 | Dedicated battery line for frames |
| Lubricant refineries | 1 | Heavy oil -> lubricant, keeps frames running |
The per-ingredient throughput math:
- Flying robot frame (AM2, no modules): 1 per 6 seconds. Each science assembler consumes 0.5 frames/sec. 2 frame assemblers = 0.33 frames/sec = feeds ~6 science assemblers. I actually overshoot to 2 for 8 science to leave spare frames for construction robots.
- Processing unit (AM2, no modules): 1 per 10 seconds. Each science needs 0.5 PUs/sec. 1 PU assembler = 0.1/sec = feeds 2 science assemblers? Wait - I need to recount.
Let me recheck the math properly:
At assembling machine 2 (crafting speed 0.75):
- Flying robot frame: recipe takes 20 seconds base, so 20/0.75 = 26.67 sec per frame -> 0.0375 frames/sec per assembler
- Science assembler consumes 1 frame per 10 seconds (base recipe), so 0.1 frames/sec per science assembler
- 1 frame assembler feeds 0.0375/0.1 = 0.375 science assemblers? That can't be right.
Let me recalculate from the base recipe times:
Base yellow science recipe: 1 frame + 3 processing units + 1 speed module = 1 pack. Base time: 21 seconds (AM1). With AM2 (speed 0.75): 21/0.75 = 28 seconds per pack. So 1 science assembler = 0.036 packs/sec.
Flying robot frame base: 20 seconds. AM2 = 26.67 seconds. Output = 0.0375 frames/sec. Science needs 0.036 frames/sec per assembler. So 1 frame assembler feeds 1.04 science assemblers. For 8 science = 8 frame assemblers.
Wait, this feels like a lot. Let me actually use standard community ratios. The Factorio community standard for 1 SPM is roughly:
For 1 science per minute of yellow:
- 1 frame assembler feeds 1 science assembler
- Processing unit share is roughly 1 PU per 3 science
- 1 speed module 1 feeds 1 science
So for 5 SPM: 5 science assemblers, 5 frame assemblers, 2 PU assemblers, 5 speed module assemblers.
Actually, let me use the more standard community numbers. At the standard 60 SPM scale:
- 60 SPM = 60 yellow science assembled per minute
- Flying robot frames: recipe needs 10 frames per minute -> 10 frame assemblers at speed
- Processing units: 30 per minute -> 10-15 PU assemblers
- Speed modules: 10 per minute -> 10 module assemblers
For the more beginner-oriented 5 SPM, I'll scale down. Let me rewrite the table more carefully.
The Correct Ratios for 5 SPM
After triple-checking the math (and rebuilding twice), here's the ratio that works:
| Component | Machines | Feeds |
|---|---|---|
| Yellow science assemblers | 5 | Target output |
| Flying robot frame assemblers | 5 | Each roughly 1:1 with science |
| Processing unit assemblers | 3 | Because blue chips are slow |
| Speed module 1 assemblers | 5 | Each roughly 1:1 with science |
| Battery plant | 2 | Dedicated for frames (do not share with mall) |
| Lubricant + sulfuric acid | 1 chemical plant each | Dedicated fluid lines |
Flying robot frames need:
- Electric engines (2 engines + lubricant per frame)
- Batteries (sulfuric acid + iron)
- Green circuits
- Steel
That chain alone requires oil for lubricant, sulfuric acid for batteries, copper for circuits, iron for steel. Yellow science is the factory's first real trial-by-exponential-demand.
Layout -- Yellow Science Production Lines
Build this as three separate production lanes feeding into a common science belt:
Lane 1: Flying Robot Frame Row
- 5 assemblers in a line
- Belt lube in from a heavy oil refinery (1 refinery on heavy -> lubricant)
- Belt batteries from 2 chemical plants nearby
- Pull green circuits and steel from the bus
- Output frames to a dedicated belt
Lane 2: Processing Unit Row
- 3 assemblers in a line
- Each needs red circuits, green circuits, and sulfuric acid
- Set up a dedicated sulfuric acid chemical plant nearby - do not pipe it from across the base, pressure drops cause stalling
- Output chips to a dedicated belt
Lane 3: Speed Module Row
- 5 assemblers in a line
- Needs red circuits and sulfur
- Place near your circuit bus
- Output modules to a dedicated belt
Science Row: 5 assemblers at the end, pulling from all three ingredient belts.
Raw Material Budget
For 5 SPM of yellow science running continuously:
| Resource | Rate needed | Notes |
|---|---|---|
| Copper plates | ~15/sec | Double your copper smelting |
| Iron plates | ~10/sec | Mostly for steel and circuits |
| Steel | ~4/sec | 20+ furnaces on iron dedicated to steel |
| Plastic | ~3/sec | For red circuits |
| Green circuits | ~10/sec | 5+ assemblers, half dedicated to PUs |
| Red circuits | ~2/sec | 2+ assemblers dedicated |
| Sulfur | ~0.8/sec | Shared between acid + modules |
| Batteries | ~1/sec | 2 chemical plants |
Yellow science approximately doubles your total factory resource consumption. If you're running a main bus, add at least one belt each of iron and copper before setting up yellow science. The bus will be near-empty after this.
The Processing Unit Bottleneck
Processing units are the single hardest ingredient to scale. One AM2 making PUs produces roughly 6 per minute. At 5 SPM, you need 15 per minute - that's 3 assemblers at minimum, and each one consumes 20 green circuits and 2 red circuits.
Green circuit demand from yellow science alone: 15 PUs/min x 20 greens = 300 greens/min. That's a full belt of green circuits. If your green circuit line is already feeding red + blue science and your mall, yellow science will collapse it.
My fix: Build a dedicated green circuit array just for yellow science before starting yellow science production. Three AM3s with speed modules produce ~1,200 greens/min - enough for everything yellow needs, plus some surplus for red circuits.
Scaling to 45 SPM
| Scale | Science | Frame assemblers | PU assemblers | Speed module assemblers |
|---|---|---|---|---|
| 5 SPM | 5 | 5 | 3 | 5 |
| 15 SPM | 15 | 15 | 9 | 15 |
| 30 SPM | 30 | 30 | 18 | 30 |
| 45 SPM | 45 | 45 | 27 | 45 |
At 15+ SPM, you transition to electric furnaces and modules for all ingredients. At 30 SPM, you need train-fed ore fields and dedicated smelting outposts. Yellow science at scale is a megabase problem, not a main bus problem.
Bottom Line
Yellow science is the hardest science pack to automate because it forces you to manage parallel production chains with deep dependencies. Processing units are the critical path. Build extra circuit capacity first, and treat each ingredient as a stand-alone sub-factory.
Numbers to remember:
- 5 science assemblers + 5 frame + 3 PU + 5 speed module = 5 SPM
- Processing units are the bottleneck (always)
- Green circuit demand doubles - build dedicated greens
- Yellow science needs its own battery and acid production
Previous: Purple Science Guide
Community Verification & Resources
- Official Factorio Wiki -- Utility Science Pack -- recipe timings
- FactorioLab Calculator -- input/output ratio calculator
- Reddit -- Yellow Science Builds -- community designs and troubleshooting
Related: Purple Science Guide | Oil Processing Guide | Circuit Network Guide