Limits RegistryPUBLIC RECORD
Limits RegistryThe Eurocopter X3, a compound helicopter combining a conventional rotor with two forward-facing propellers, reached 472 km/h (293 mph) in level flight during a June 2013 test — the fastest helicopter-type aircraft ever flown, well beyond the roughly 300-370 km/h ceiling of conventional helicopters.
The question, scope, and sources behind this Registry record.
The Eurocopter X3, a compound helicopter combining a conventional rotor with two forward-facing propellers, reached 472 km/h (293 mph) in level flight during a June 2013 test — the fastest helicopter-type aircraft ever flown, well beyond the roughly 300-370 km/h ceiling of conventional helicopters.
The highest speed ever achieved by a rotorcraft, including hybrid compound-helicopter designs that supplement rotor lift with forward-thrust propulsion.
Change a parameter to stress-test whether a proposed result is still inside the published specification. This is an audit aid, not a proof checker.
This record has no editable parameters. Read the formal question and assumptions before challenging it.
Current frontiers derived from accepted Claims.
An observed or demonstrated result; no opposing bound is implied.
The frontier is not sacred
Most progress starts with a disagreement that survives contact with evidence. If you can push the known lower bound up or pull the upper bound down, show us the work.
≥ when you have shown that at least this value is achievable.≤ when you have shown that anything above this value is impossible.No vibes. State the value, define the scope, and link the paper, proof, code, or reproduction that lets another person check it. Editors review every challenge before the public record changes.
Challenge this recordAssertions tied to evidence, attribution, and review.
The frontier as it changed over time.
Only accepted Claims matching the current specification contribute to the displayed bounds. Strict inequalities remain open; contradictory Claims require editorial review.
Permanent ID limitsregistry.com/limits/LR-FASTEST-HELICOPTER
No active verified bounties are linked to this Limit.
View verified bounty tracker ↗No accepted machine-checked reproductions are recorded for this Limit.
Limits Registry. LR-FASTEST-HELICOPTER. Fastest helicopter. 2026.