'heat' played heck some days with a helicopter's ability to lift different payloads in Vietnam. And sometimes they just could not hover for a penetrator device or basket to go down.
Flew with some pilots who could take an over-loaded Huey on a hot day - and run it across the ground or PSP....or down a long grassy slope until something they called 'ground effect' came into play --- and the Huey would fairly 'leap' ......and we're flying...and breathing again. Come in so hard we'd bend the skids if there wasn't room to land like a airplane.
They did this so many times when trying to evac critically wounded. Taking too much fire to even consider making a second or third approach to a hot LZ - they would touch down and have wounded tossed and loaded and unceremoniously piled in and then pull the temps and revs into the RED....move forward, sometimes whacking off tree limbs and dive down the ridge...and by God we were away!
Bear in mind the ages of these pilot warrant officers. They had to be between 18 and 28, if I recall, but most were right around 20>22 yrs old. Crazy young bucks - and the youngsters who flew with them (crew chief, gunners and medic) could be just as goofy. But, don't mistake that for lack of professionalism. These guys took their jobs very seriously...and were good at it.
Anyway. Yeah heat and flying don't always work well together.
Stig