This was made possible because of two reasons:
1) The average hashing power per chip has been beefed up significantly from our estimated 300Khs per chip to 800Khs per chip and thereby reducing the number of chips required to reach the required hashes.
2) Earlier we were planning to stack miner boards vertically one over the other, however after the reduction in the number of chips we decided to go horizontally and increase the depth of the 1u chassis in order to accommodate the boards horizontally. The boards will be connected to each other through ribbon cables. By stacking boards horizontally thermal design improves as stacking of boards vertically will have passed the heat to all the boards which were above them. With efficient heat sinks having sizeable fins heat can be dissipated in the chassis by channelizing the heated air properly with the directed fans. If we need to we can also go for conduction cooling through the chassis itself.
A technical drawing will be shared in due course once we have finalized both the board and enclosure sizes.
I do look forward to this technical drawing. I appreciate your response, but again, increasing the density of the chips and the speed, requires more power. More power = more heat, unless there's a significant catalyst for greater efficiency.
While I don't believe it impossible, I do find it unlikely to be 'that simple', especially for air cooling to solve the problem.
I look forward to being shown otherwise, of course.