Orbital overlap occur in cumulene? what types of orbital overlap occur in cumulene? -s/sp^2 -s/s

The carbons on the ends are sp² hybridized, with a p-orbital for the 'second' bond in the double bond with their neighboring carbons. 

They have those sp² orbitals overlapping with the s from the hydrogen, and they have a p overlapping in the pi bond with the neighboring carbon. They also have a sigma bond with the neighboring carbon I'll get to. 

The middle carbons each have two pi bonds with their neighbors, leaving sp hybridiaztion for the rest. So they have sp/sp² with the end carbons, and sp/sp with each other. (And they also have p/p in the pi bonds). 

So the total list is: 
s/sp² 
p/p 
sp/sp² 
sp/sp

The air is going to come out because of the low pressure.