Why the Ferrum 50 Exists

The standard narrative around FPV frames is: Chinese manufacturers make them cheap, everyone buys cheap, they break, they buy again. We were those pilots. We went through frame after frame flying bando in and around Wrocław. Standard 5mm arms on concrete walls ended sessions. Parts availability for anything 18 months past launch was a lottery.

The Ferrum 50 started as an internal project: build the frame we actually want to fly on. The requirements were specific. 7mm arms minimum. T700 carbon sourced for stiffness-to-weight rather than price. Geometry validated with real aerodynamic simulation, not copied from another frame. OEM spare parts available indefinitely. That was the brief.

The 7mm Arm Decision

This was the non-negotiable. We'd been flying 5mm frames for years and knew the failure pattern: arm breaks at the root on a direct concrete impact, session ends, replacement ordered, 5-7 days wait. At 7mm, the arm survival rate on the same impacts changed dramatically. Not invincible - 7mm arms still break on hard enough impacts - but the threshold moved from "any serious wall hit" to "genuinely catastrophic impact."

The weight penalty is real. A 7mm arm is heavier than a 5mm arm. We accepted that trade. Pilots who crash in concrete environments and need to keep flying made the same trade without hesitation.

The Carbon Sourcing

Most FPV frame carbon comes from the same pool of suppliers in the standard supply chain. The quality is T700, but the sourcing parameters (resin system, layup process, fiber volume fraction) aren't specified for FPV vibration characteristics - they're specified for price. We sourced outside that supply chain specifically to get consistent stiffness-to-weight characteristics that minimize vibration transmission to the FC.

The result shows in Blackbox data. Lower pre-filter gyro noise floor than comparable 5mm frames we tested against. Less filtering required. Cleaner tune.

The CFD Validation

We used Siemens enterprise-grade CFD software to validate the arm geometry at freestyle speeds. The goal was to find the arm angle and motor position combination that minimizes induced drag from arm turbulence entering the props - which affects both efficiency and vibration.

The Squashed X geometry came out of this process. It's not a copy of any existing frame geometry. The motor positions are where the CFD said they should be, not where convention placed them.

The Interlocking Arm System

Standard frame arms bolt through the top and bottom plate with screws. Under repeated hard impacts, the arm can rotate in its mount - creating micro-movement that worsens over time and eventually causes premature stress cracking at the bolt holes. The Ferrum 50 uses an interlocking geometry at the arm-to-center joint that prevents rotation without relying purely on screw tension. The arm geometry locks against the center plate structure.

Practical result: arm joints stay tight longer under repeated impacts. Field observation over 12+ months of bando use confirms this.

What We'd Change for the Next Version

We're not perfect. Here's what we're thinking about for the next iteration:

Arm-to-center geometry at the top plate. The current design has a very slight tolerance that shows on some units. Tightening this is on the list.

VTX placement options. The DJI O4 Pro placement works well but limits flexibility for some alternative systems. More mounting position options would make the frame work better across more VTX configurations.

Weight. The 7mm arms add weight. We haven't found a way to get 7mm durability at 5mm weight with current materials. When we do, we'll build it.