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Message: <blockquote data-quote="Olgar Shiverstone" data-source="post: 787082" data-attributes="member: 5868">That's a pretty complicated question -- there isn't one simple equation that will give you speed for a given thrust at all operating points -- each operating point is actually different.  Equations are also different between prop-diven and jet aircraft (propr are a function of power available, jets a function of thrust available).Note, too, that "speed" is an inexact term.  Which speed do you mean?  True airspeed, indicated air speed, ground speed? In level flight or climbing, at what operating point?To give you an idea of the variables involved, you need:- Thrust available, thrust required for level flight (thrust available also depends on things like air temp, altitude, and velocity)- Free stream air density (depends on altitufe & air temp)- Aircraft weight (which changes as you burn fuel)- Wing area- Aircraft total surface area- Lift coefficient (depends on wing angle of attack and airfoil)- Drag coefficients (profile, viscous, and induced -- also depend on airfoil, angle of attack, and aircraft design factors)- Oswald efficiency factor (how "drag-efficient" the design is).- Aspect ratio (wing span squared over area)You could get a rough approximation by creating a free body diagram showing thrust, lift, weight, and drag (which requires you to calculate those parameters using the information above), and resolving the horizontal components of those forces (for your given angle of attack, assuming level flight) to give you a net horizontal force, which will give you an idea (based on aircraft mass) how fast the aircraft can accelerate.  By plotting a curve of available force versus drag (known as the thrust-required curve_, you can find the operating point for crusing velocity, depending on if you need max range or endurance, or something in between.  That thrust required curve is aircraft-specific, depending upon the factors above.Olgar (dwarven Aero Engineer)</blockquote>

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