Now this one can make Amazon delivery easier

http://www.roboticstrends.com/article/hycopter_drone_flies_for_4_hours_via_hydrogen_power

This one is similar to the Hydrogen powered cars.

Woah this is super friendly..and Anwar sir please convey these thoughts to amazon
Still wondering how to make a frame like that using hydrogen 

Is this actually possible?
If hydrogen is compressed then have much weight, and loosely filled hydrogen is enough for 2.5 h flight?

Hypothesis.. Can't be possible..actually logically thinking it cannot be done..
Agreed with akhilzid sir

Our team had a meeting last month with HES team visiting india. They will be setting up a unit in india soon and yes it is very much possible.

This seems highly unlikely. 120gms hydrogen shall have a total available energy of 3900W or 3.9 kW, assuming the most efficient fuel cell at 75% , that gives a output of 2.9kW... So I don't think it viable at all

This another  Canadian company which set a world record in multirotor flight time. 3 hour 43 mins.

too true to believe....

just checked their website.....n guess what I found.
..10 hrs of flight time..... 

http://www.energyor.com/products/detail/h2-endurance-uav#included

this is truly amazing....

As per their vid ....they achieved this in 2011

Look at the size of the tank, it certainly has at least 2-3 KGS of of Gas in it. While the one claimed to have 10 hour endurance is an aircraft. Aircraft typically dont need as much energy to fly as quads. While the original horizon quad has only 120 GMs of Hydrogen