Big rucksacks need to tick many boxes to perform well. Our experts explain what these 'must-haves' are and recommend our top-rated tried and tested 50+ litre backpacking rucksacks.

1.An expandable hard-shell carry-on suitcase with four spinner wheels and a built-in lock to bring your luggage firmly into adulthood with you. RIP, soccer camp duffel bag. You will not be forgotten.

JetBlue: Carry-on bags should not exceed 22 by 14 by 9 inches, but underseat personal items can’t be bigger than 17 by 13 by 8 inches. United Airlines: United limits underseat luggage to 9 by 10 ...