After a short vertical climb, a rocket tips slightly and lets gravity bend its path towards horizontal — a gravity turn — so it gains sideways speed without large side loads.
Watch any launch and the rocket goes straight up for only a few seconds. Then it starts to lean and its path curves over, out to sea. This is deliberate. To reach orbit a rocket needs mostly sideways speed, and the curve is how it gets there safely.
Rocket designers usually split the early climb into three parts:
In the gravity-turn phase the rocket flies with almost zero angle of attack — it points exactly where it is going. The air then flows straight along it, so there are no big sideways forces trying to bend or break it. NASA's Ares I study chose this flight style to keep bending loads low and make booster separation safe.
Turning sharply in thick air would put huge sideways loads on a long, thin rocket. Going straight up for too long would waste propellant fighting gravity without building sideways speed. The gravity turn is the compromise.
ISRO's flight sequence for LVM3 gives a feel for the shape of the path. The L110 core ignites at about 41.5 km after about 113 seconds. The fairing is dropped at about 115 km after about 217 seconds. The satellite is released after 974 seconds into an orbit whose lowest point is about 180 km.
So after the first few minutes the rocket is gaining height only slowly. It spends most of its 16-minute flight building speed sideways.
Note that an LVM3 satellite is released about 16 minutes after lift-off — most of that time goes into sideways speed, not height. See LVM3's flights
The NPTEL lecture writes the gravity turn in terms of the flight-path angle θ, measured from horizontal. With thrust T along the velocity, mass M and speed V (drag ignored):
dVz/dt = (T/M)·sin θ − g dVx/dt = (T/M)·cos θ dθ/dt = −(g·cos θ) / V
The last equation is the key. The turning rate depends only on gravity and speed. Thrust does not steer the rocket at all; gravity does.
Worked numbers (g = 9.81 m/s²):
As the rocket speeds up, the turn slows down. That gives the smooth, flattening arc seen in launch videos.
The lecture also notes the limits. A pure gravity turn inside the atmosphere would spend too long in the dense lower air, where drag adds up. Real ascents mix segments: vertical rise, a short constant-rate pitch-over, then a gravity turn through the region of peak dynamic pressure (q = ½ρV²), which is a key structural design case.
Above the atmosphere, upper stages fly a different guidance law. In the Ares I plan, the upper stage switched to a linear-tangent steering profile chosen for the best use of propellant to reach the target orbit.
A flight path in which the rocket keeps its thrust along its velocity (zero angle of attack) and gravity gradually bends the path from vertical towards horizontal.
Pointing exactly along the direction of travel avoids large sideways aerodynamic forces, which keeps bending loads on the long, thin rocket low.
Slower. The turning rate is inversely proportional to speed V.