How can air launched UAV's be decelerated? I am working on disaster relief drones for a college project. I was thinking about having multiple set of drones launched from an aerial vehicle over the disaster prone area. That's when I came across a big challenge.

How would you effectively decelerate a UAV that is air launched from an aircraft which is flying at a much greater speed than the maximum allowable speed of the UAV? 

The stall speed of the aircraft is much larger than the maximum speed of the UAV (assuming, it has to be a very low cost UAV and hence the idea of having a parachute for deceleration is not very effective).

I would be glad if anyone could suggest me simple and robust ways to do achieve this.
......the same way you decelerate any other kind of aircraft.  Once released from the Mothership at idle power, it slows down until reaching an appropriate cruise speed thence power is increased to maintain speed.

If the release speed of too high for the UAV, one might use some kind of a frangible capsule equipped with a drag chute or other high drag device of some sort to enclose the drone during launch, thence the capsule fractures once the speed is slow enough, releasing the drone to begin flight under its own power.