The Osprey Flight Helmet Rucksack is purpose built to replace the standard issue flight helmet bag. Fight and Flight Tactical started with the dimensions of the venerable medium ALICE ruck and modified it to fit, not only a flight helmet, but a ton of support gear as well.
The Osprey is padded throughout its construction to protect the flight helmet and the other sensitive contents of the bag like night vision devices. It has a large main compartment and a padded trunk on top to keep you organized. It has a ton of PALS webbing coverage so you can attach additional pouches to it. The bag is lined with a water-resistant pack cloth type liner and all the seams have been sealed to make the bag very water resistant.
I am really just scratching the surface of the features that this bag has so hit the link to learn more. Check out the Osprey Flight Helmet Rucksack from Fight and Flight Tactical.
Do you have a picture of the Rucksack when worn? Just to see the size in relation to a person.