Yedyr Engines
Propulsion technology distinguished by exceedingly precise controls, high speed, and a distinctive auditory signature. Yedyr engines are significantly more expensive than conventional alternatives, making them impractical for most planetary travel. On Lukyr Arix, however, they are the only viable option for surface transit due to the planet's destroyed, toxic, and unstable terrain.
Technical Characteristics
Precise control: Essential for navigating hazardous environments like Arix's surface, where sudden maneuvers are necessary to avoid industrial hazards and unstable ground.
High speed: Capable of suborbital flight, allowing rapid transit across planetary distances.
Electric operation: Yedyr engines produce an "electric heartbeat" sound during operation.
Cost: Significantly more expensive than conventional engines, making them economically impractical on most planets where ground vehicles or traditional aircraft suffice.
Sound Signature
Zet's spider bot, while traveling on the underside of a taxi approaching the Regional Spaceport on Lukyr Prime, hears and recognizes the engine sound despite never having physically heard it before (IWUKE Chapter 10):
Description:
- "A deep, harmonic hum"
- "Overlaid with an electric sound"
- "Crackling rhythmically like a heartbeat"
- "The sound seemed to be silencing everything around it"
Zet's recognition:
- "I had never heard it, but I knew it from descriptions"
- Immediately identifies it as Yedyr engines
- Uses it to deduce proximity to the regional spaceport
Kynon Bancroft hears the same "electric heartbeat" in a Novaris Dynamics Lightning8000 during takeoff from Arix Theta-7 (SFL-TE Chapter 2).
Usage Patterns
On most planets: Ground vehicles or traditional aircraft are preferred. Yedyr engines are considered too expensive for routine use.
On Lukyr Arix: Yedyr-powered suborbital craft became the standard "long ago" because the surface is too damaged for conventional travel. The precision controls are "simply a must" to avoid dangers, and speed is necessary to minimize exposure time.
On Lukyr Prime: Yedyr engines are heard at spaceports and orbital facilities, suggesting use for spacecraft launch and docking operations.
Known Manufacturers and Models
Novaris Dynamics, a ySteel subsidiary, manufactures the Lightning8000 suborbital traveler — a Yedyr-powered craft used for prisoner transport on Arix. The Lightning8000 is capable of autonomous flight (no pilot required).
Operational Considerations
Yedyr engines require skilled operation. In SFL-TE Chapter 2, Kynon Bancroft experiences rough handling during takeoff and notes the engines are precise "but clearly, not everyone knows how to use them." Despite this, the craft successfully navigates a violent Arix storm within seconds, demonstrating the technology's capability even under poor piloting.
Vulnerability to extreme weather: In SFL-TE Chapter 6, while caught in a massive supercell "century storm," Kynon observes "a severely damaged Yedyr traveler crashing — or emergency landing. In this kind of situation, the two were difficult to tell apart." The storm's sudden formation and expansion prevented even properly-operated craft from avoiding it. This demonstrates that while Yedyr engines are the only viable option for Arix surface travel, they are not invulnerable — catastrophic weather events can destroy even these advanced craft.
Implications
Acoustic dominance:
The sound "silencing everything around it" suggests extreme volume or sound pressure, creating an unmistakable presence.
Knowledge distribution:
The engines are distinctive enough that descriptions exist in Zet's knowledge base (loaded by Lucas Taldo) and the sound is culturally recognizable on Lukyr Prime, associated strongly with spaceports.
Technology type:
The "electric sound crackling rhythmically" suggests electromagnetic or plasma-based propulsion rather than chemical combustion. The harmonic hum implies resonance or frequency-based operation.
Open Questions
- What does "Yedyr" refer to — a company, a principle, a material, or a person's name?
- What propulsion principle do Yedyr engines operate on?
- Is the sound a byproduct or an intentional safety feature?
- What is the cost differential compared to conventional engines?
- Are they used for atmospheric flight only, or also for orbital insertion and interstellar travel?
- Do all spacecraft use Yedyr engines, or only certain classes?