Here is the current term:If below it different substantially compared to how it appears in your app/software, be sure to update your software/app's content prior to using this form.
Critical Mach Number
In aerodynamics, the critical Mach number (Mcr) of an aircraft is the lowest Mach number at which the airflow over some point of the aircraft reaches the speed of sound, but does not exceed it.
For all aircraft in flight, the airflow around the aircraft is not exactly the same as the airspeed of the aircraft due to the airflow speeding up and slowing down to travel around the aircraft structure. At the critical Mach number, local airflow in some areas near the airframe reaches the speed of sound, even though the aircraft itself has an airspeed lower than Mach 1.0. This creates a weak shock wave. At speeds faster than the Critical Mach number the drag coefficient increases suddenly, causing dramatically increased drag, and, in an aircraft not designed for transonic or supersonic speeds, changes to the airflow over the flight control surfaces lead to deterioration in control of the aircraft.
In aircraft not designed to fly at or above the critical Mach number, shock waves in the flow over the wing and tailplane are sufficient to stall the wing, make control surfaces ineffective or lead to loss of control such as Mach tuck.
source: Wikitionary / Wikipedia and Related Sources (Edited)
Please do not use this form to tell us that the definition you saw doesn't necessarily match the context where you saw it. We use an automated keyword-based system to match the tens of thousands of definitions in our glossaries with our material. Sometimes, when a term has more than one meaning or use or when an abbreviation might stand for more than one thing or resemble a 'normal' word, this results in a definition for a term being shown that doesn't necessarily match the context. Please do not report such issues here. Rather, please use your best judgment to evaluate whether such definitions apply to what you're reading. If the answer is 'no' but nevertheless you feel the term doen't have a good definition in our system but should, please go back and find the 'suggest a term' link in the app. Thanks!
We welcome your feedback.Please carefully fill out the specifics below. If you wish to comment on more than one term/definition, please fill out and submit this form separately for each.
Specifics:
Please Identify Yourself.It's important, so that we can get back to you with feedback or requests for clarification.
Name
E-Mail
Please enter your email address above solely for the purpose that our editorial team might, if necessary, contact you with questions, comments, or requests for clarification.