Why does weight affect maneuvering speed

Let me explain. Airplanes flown at weights below their gross weight require less lift for straight and level flight. Changes to the airfoil geometry from high-lift devices such as flaps or leading-edge slats increase the maximum coefficient of lift and thus lower stall speeds. Here, we look at two lesser-known factors affecting stall speeds: center of gravity location and thrust produced. Well, stall speed is usually defined by wing lift curve, and not so much affected by the landing gear. Usually the limitation is on the upper side due to separation.

Climb speed is basically engine thrust minus drag, the drag increases the climb speed is lower. Variations in aircraft weight do not affect the glide angle provided that the correct airspeed is flown. When pitch is reduced, the glide angle increases and the distance traveled will reduce. When weight is increased on an aircraft, it needs to fly at a higher angle-of-attack to produce more lift, opposing the aircraft's increase in weight. This increases both the induced drag created by the wings and the overall parasite drag on the aircraft.

DMMS: Defined minimum maneuvering speed. This is similar to the speed that airline pilots polled in the video are referencing when they talk about maneuvering speed being a minimum, not a maximum. Gryder calculates the number as 1. Less lift means the airplane can be flown at a smaller angle of attack. In other words, an airplane at 2, pounds may require a 4. Vo maximum operating maneuvering speed is a limiting load factor which is also determined by the aircraft designer.

Va is the maximum speed the aircraft can be stalled without exceeding the limit load factor 3. Vno is based on the maximum speed at which the aircraft can encounter a 50fps vertical gust and not exceed the limit load factor. Weight Shift Instead of calculating a weight and moment for every section of the aircraft, it is only necessary to compute the original weight and moment—then, the effect of the change in weight.

Therefore, the CG shifts. The FAA defines Vno in the Pilot's Handbook of Aeronautical Knowledge as " the maximum speed for normal operation or the maximum structural cruising speed.

Let's say you pull back on the yoke abruptly until you hit 3. If your stomach doesn't stop you, your airframe might. Those rolling Gs can cause structural failure, even though you never exceeded the G limits. Move one control elevator, rudder or aileron , in one direction , in smooth air. I broke each test out in a separate point for a specific reason. They're not tested as "checked maneuvers," where the controls move forward and back in quick succession. Each of those movements is an independent test.

Manufacturers do certify one checked maneuver, and they perform the test at speeds above V a. The test pilot suddenly moves the elevator aft, and then moves it forward.

But, the movements are carefully executed so that they don't exceed the aircraft's G limits. The test pilot also performs the maneuver using a limited amount of angular acceleration. Manufacturers normally don't test checked maneuvers using the ailerons or rudder. Those tests will be done if the aircraft's approved for "flick" maneuvers, like snap rolls. So, if you're flying a normal category aircraft with a positive limit of 3.

If you try that maneuver at the full 3. When the manufacturer certifies V a , they do it at maximum gross weight. But, as your weight decreases, V a also decreases. This confuses nearly everyone. As you increase G loading, your angle of attack also increases.

If you're flying at V a and you pull the yoke back to the stop, your angle of attack will increase and you'll reach the critical angle of attack right as you hit the G limit. In other words, you'll stall right before you break. If you're flying at your certified V a speed, but you're below max gross weight, you'll fly at a lower angle of attack. As you pull back and increase Gs, you'll hit your G limit before you reach the critical angle of attack. So, as you lose weight, your V a slows down, putting your 1 G angle of attack back in the safe range.

Most aircraft flight manuals and operating handbooks have a chart to compute V a at various weights. If your handbook doesn't have a chart, you can use the following formula:. They say every FAR is written in blood. Any increase beyond the critical angle of attack results in a stall. For the purposes of calculating maneuvering speed in the examples below, we will use a critical angle of attack of 18 degrees. Our examples will assume a linear or one- to-one relationship between lift and angle of attack as the graph below depicts, whereas a doubling of the AOA would produce a doubling of lift.

Assume an airplane at gross weight is flying straight and level at knots. At that weight and speed, this aircraft requires an AOA of 3 degrees to produce sufficient lift to maintain level flight. If turbulence or manual input increases the AOA from 3 degrees to 6 degrees, the lift doubles and the load factor doubles to 2Gs.

The load continues to increase as the AOA increases, until its critical angle of attack of 18 degrees is reached. As stated previously, the maximum load G-force is reached at the critical angle of attack of 18 degrees because any further increase in the AOA would result in a stall, thus eliminating the load altogether. In this case, you should slow down because flying slower will require a higher AOA to maintain level flight. A higher AOA in level flight would put you closer to your critical angle of attack.

For example, if a slower speed requires an AOA of 5 degrees to maintain level flight, the load would max out at 3. Another determining factor is the aircraft weight. For example, an airplane at 2, pounds may require a 4. Again, with a reduced AOA of 3 degrees, a 6G load could be generated by a strong gust of turbulence before stalling at the degree critical angle of attack.

In turbulence, you want a high AOA in level flight to reduce the multiplier before reaching your critical angle of attack. Now for the rest of the story. Traditionally, we were taught that flying at or below maneuvering speed would protect us from structural damage during turbulence or from a rapid control deflection from one extreme to another.

We now know there are exceptions.