Meanings
- uncountableAn excessively-low speed; a speed lower than the minimum operating speed.
An underspeed switch drops the load off if engine speed falls to 380 r.p.m. and an overspeed governor shuts the engine off if its speed rises above 1,700 r.p.m.
1961 August, “The English Electric Type 5 3,300 h.p. "Deltic" diesels for British Railways”, in Trains Illustrated, page 4691 more example
These boundaries can vary from prelaunch predictions due to changing atmospheric conditions and variations in SRB and main engine performance. Using this real-time information, a computer and software program called the Abort Region Determinator (ARD) allows MCC to predict the underspeed that will result from a loss of performance (engine failure, throttle lockup, degraded thrust, etc.). This information is then used to predict the actual abort mode boundaries on which the real-time voice calls are made. These boundaries vary from pre-flight predicted boundaries.
2006 October 10, NASA, “2.2.1 Voice Calls”, in Intact Ascent Aborts Workbook 21002, archived from the original on 25 Jun 2022, page 2-3
Synonyms & antonyms
Origin
Translations
Finnish alinopeus
- alinopeusspeed lower than the limit
Cite this entry
underspeed. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/underspeed
“underspeed.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/underspeed. Accessed November 3, 2026.
WatkinsX Dictionary, s.v. “underspeed,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/underspeed.
Source: underspeed on Wiktionary, CC BY-SA 4.0.