GATE AE case studies

GATE AE · Put your knowledge to work in context.

GATE Aerospace Engineering (AE) is one of the subject papers of the Graduate Aptitude Test in Engineering, a national examination used for admission to postgraduate engineering programmes in India, for recruitment by several public-sector undertakings, and as a recognised credential in applications to research programmes and some overseas institutions. Candidates usually sit it in their final undergraduate year, shortly after graduating, or later while working, and the resulting scorecard stays valid for three years. The GATE AE case studies are 5 cases and about 5,116 words.

Transonic Cruise Margin on a Swept Business-Jet Wing

A 30-seat business jet is being cleared to raise cruise from M 0.80 to M 0.82 at FL410. The wing carries 25° quarter-chord sweep at the root and 20° outboard of the flap hinge; the wing box, section thickness and powerplant stay unchanged.

1,062 words, about 5 min 2

Pitch-Rate Autopilot Oscillation Caused by Unmodelled Lag and Light Damping

An attitude-hold autopilot for a 900 kg UAV was designed from a rigid-body model. The pitch-rate response to elevator, in (deg/s) per deg, is q/δe = 3.0/[(s/3.5)² + 0.9(s/3.5) + 1], that is, a short-period mode at 3.5 rad/s with damping ratio 0.45.

933 words, about 5 min 3

Compressor Surge on a Hot-Day Slam Acceleration

The 9-stage high-pressure compressor of a medium-bypass turbofan surges twice during a slam acceleration from ground idle on a day 25 °C above ISA; on a standard day the same schedule is clean. Telemetry at the instant of surge shows 84% N2, corrected compressor flow 21.6 kg/s, compressor pressure ratio 6.80 and fuel flow 2.60 kg/s.

990 words, about 5 min 4

Crack Found at a Wing Fastener Hole: Life and Inspection Interval

At a C-check a 16 mm through-crack is found at a fastener hole in the lower wing skin of a transport aircraft (2024-T3, K IC = 33 MPa√m, skin 3.2 mm thick). The hole sits well inside a 150 mm stringer bay, so the crack is treated as a centre crack in an infinite plate with geometry factor Y = 1.12.

1,025 words, about 5 min 5

Choosing a Transfer Strategy from LEO to Geostationary Orbit

A 4,500 kg communications satellite, including 220 kg of hydrazine reserved for station-keeping, is injected into a 300 km circular orbit at 28.5° inclination. The apogee engine has 420 N thrust and Isp 310 s (effective exhaust velocity 3.04 km/s); its propellant is carried separately from the hydrazine.

1,106 words, about 6 min