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Educational content for pilots who want to understand their aircraft at a deeper level.
Educational content for pilots who want to understand their aircraft at a deeper level.
Real answers with real physics. No hand-waving.
Ps is the rate at which your aircraft can gain or lose energy at a given flight condition. Positive Ps means you have excess thrust over drag—you can climb or accelerate. Negative Ps means you're bleeding energy—you'll slow down or descend. Zero Ps is energy neutral: you can maintain that airspeed and altitude, but you have nothing left to climb or accelerate. It's not the edge of your envelope—it's equilibrium for those specific conditions.
Corner velocity is maneuvering speed (Va). It's the exact point where the lift limit (stall boundary) meets the load limit (structural G limit)—literally the corner of your V-n diagram. At corner velocity, you can pull to the aircraft's structural limit without exceeding the stall. Fly slower, and you'll stall before reaching max G. Fly faster, and you risk exceeding structural limits before stalling. It's where your aircraft turns tightest at maximum G.
Best rate of climb speed (Vy) decreases with altitude because the power available and power required curves shift differently as air density decreases. The point of maximum excess power moves to a lower indicated airspeed. The EM diagram shows this clearly—you can see how the Ps contours shift and where maximum climb performance lives at different altitudes.
No. The published Vmc is tested under very specific conditions: max gross weight, most rearward CG, sea level, critical engine windmilling, 5-degree bank into the good engine, takeoff power. Change any variable and your actual Vmc changes. Lighter weight? Vmc goes up. Higher altitude? Vmc goes down. Wings level instead of banked? Vmc goes up significantly. You almost never fly with all the test assumptions met.
Dynamic Vmc is TALLYAERO's real-time calculation of your actual minimum control speed based on your current conditions—not the POH number. We calculate how Vmc shifts when you're at lighter weights, higher altitudes, different configurations, and various bank angles. Since you're almost never flying at the exact conditions where Vmc was tested, knowing your actual Vmc tells you what your real safety margins are during training and OEI flight.
Lower weight means less rudder authority is needed to counteract the yawing moment from asymmetric thrust—but it also means the rudder produces less force at a given airspeed. The net effect: Vmc increases as weight decreases. That's why the POH Vmc is tested at max gross weight—it's the lowest (most favorable) Vmc the aircraft will see. At lighter training weights, your actual Vmc is higher than published.
The goal in a steep turn is to maintain altitude, not lose it. What the EM Diagram and Overlay tools show you is where you are in relation to the edges of your envelope during the maneuver. At 45 degrees of bank, you're at 1.4G—your stall speed has increased 19%. At 60 degrees, you're at 2G and stall speed is up 41%. Understanding your stall margin and load factor in real-time explains why instructors tell you to stay coordinated and not get slow—you're creeping toward the lift limit.
Because the stall boundary has moved toward you. In level flight, your stall speed might be 50 knots. In a 60-degree bank at 2G, that stall speed is now 71 knots. If you entered at 100 knots and let the nose drop or power decay, your margin to the stall shrinks rapidly. The EM diagram shows this visually—you can see exactly how much margin you have between your current state and the lift limit at any bank angle.
Yes. The overlay tool shows students exactly what happens to energy state throughout a maneuver—not hand gestures or whiteboard sketches, but actual physics plotted on real terrain. Students can see why the maneuver is designed the way it is, where the energy trades happen, and what the consequences of deviations are. It's ground instruction that transfers directly to understanding in the aircraft.
No. The "1,000 feet and you're good" rule is an oversimplification that gets people killed. Whether you can make it back depends on your specific aircraft's glide performance, your reaction time, the wind, your weight, your actual climb gradient on that day, and how far you've traveled from the runway. A heavy aircraft on a hot day with a tailwind on departure might need significantly more than 1,000 feet. There is no universal altitude that guarantees a successful turnback.
Most pilots brief an oversimplified decision matrix without any backend testing or real thought. "Above X altitude, I'll turn back" isn't a plan—it's a guess. A real brief accounts for your aircraft's glide ratio, your expected climb performance that day, the wind direction and velocity, and the specific geometry of the departure runway. The Overlay tool lets you model the actual turnback with your actual aircraft on your actual airport.
Wind changes everything. A headwind on departure (tailwind on return) significantly helps your turnback—you're climbing into wind and gliding back with it. A tailwind on departure does the opposite—you've traveled further from the runway during climb and now face a headwind on the glide back. The same aircraft at the same altitude might easily make it back with one wind condition and have no chance with another. The Overlay tool models this for you.
The delay between engine failure and beginning your turn costs altitude. The average pilot takes 3-5 seconds to recognize the failure and begin the turn. During that time, you're decelerating, possibly with the nose still climbing. That delay alone can cost you 100-200 feet of altitude and significant distance traveled away from the runway. The Overlay tool lets you factor in realistic reaction times, not the instantaneous response that simple calculations assume.
A Cirrus SR22 and a Cessna 152 have very different glide ratios, climb rates, and turn performance. A lightly loaded trainer climbs fast, covers less ground, and glides efficiently. A heavy high-performance single climbs shallow, travels further, and may have a worse glide ratio. Your specific aircraft at your specific weight on that specific day determines whether the turn is possible—not a rule of thumb from ground school.
The Overlay tool plots your actual turnback on the actual airport satellite imagery. You set your aircraft, weight, climb rate, wind, and reaction time. It shows you exactly where you'll be when you start the turn, how much altitude you'll lose in the turn, and whether you'll make the runway—or how short you'll be. Change any variable and watch the outcome change. It's the tool for making a real turnback decision, not a guess.
See these concepts in action with the TALLYAERO performance tools.