Equations

Equations, formulas, and other rule of thumbs

Formula	Equation	Notes
Moment	Weight x arm
C.G in % MAC	CG distance aft of LEMAC/MAC	LEMAC: Leading edge mean aerodynamic chord
Center of gravity	Total moment/Total weight
Tire hydroplaning speed	9 √ tire pressure(psi)
Radio range formula	R = 1.25√HT + √HR	HT = Height of transmitter, HR = Height of receiver
Equal time point (distance)	ETP = (Total distance x inbound groundspeed)/(outbound groundspeed x inbound groundspeed)
Equal time point (time)	ETP distance/outbound groundpseed
Point of no return (distance)	Total endurance x (Outbound groundspeed x Return groundspeed)/(Outbound groundspeed/Return groundspeed)
Point of no return (time)	PNR distance / outbound groundspeed
Point of safe return (distance)	Endurance minus reserve x (Outbound groundspeed x Return groundspeed)/(Outbound groundspeed/Return groundspeed)
Point of safe return (time)	PSR distance / outbound groundspeed

Radio navigation instruments, their frequencies, and range

Other rule of thumbs and useful info

Emergency frequencies	VHF 121.5, UHF 243, ELT 406
Having an aft CG…	aircraft less stable and stall at a lower airspeed
Structural icing occurs usually in the range	0 - 10 degrees
Mountain flying	Actual horizon is base of mountain
Mountain flying	Stay on the updraft side of the canyon
Mountain flying	Approach mountain ridges at 45 degrees
Approximate AOA before stall	18 degrees (For most airfoils)
Glide ratio	A glide ratio of 17:1 means that the aircraft will travel 17000 ft distance for each 1000 ft altitude loss

Disclaimer: These rules of thumbs are not intended to be exact or precise! Use them for your information or at your own discretion