JP Aerospace’s design proposal was found to be technically flawed in an independent analysis by Robert Pickar. Specifically, the design assumes that electric propulsion, powered by solar cells, are sufficient to power the vehicle into orbit. In fact, the thrust generated by electric propulsion is insufficient to overcome atmospheric drag. Thus, the ATO craft would not accelerate beyond a low velocity.
Electric propulsion is inherently power-limited, that is, the thrust generated by an electric rocket engine is limited by the power of the electric power source supplying it. Given the intensity of sunlight on solar cells (the solar constant), there is a finite amount of electric power that can be generated. For ATO, this would amount to some 10 MWe. Electric rocket engines can produce about 25 newtons (6 lbf) per MWe of power. Thus, a maximum of 250 N (60 lbf) could be produced. Atmospheric drag on the ATO vehicle comes to about 11,000 newtons (2,500 lbf). The thrust is far lower than atmospheric drag, and the vehicle will not accelerate.
Additionally, the ATO vehicle would have power cut off during the night. JP Aerospace claimed that this would be handled with regenerative fuel cells. However, regenerative fuel cell systems have a specific mass of 600 W/kg. Replacing the solar cell power with fuel cell power would result in a large fuel cell. The system would be 100 times the vehicle mass itself.
These are all reasons why the ATO concepts appear to be unworkable from the physics standpoint in its present design. According to the skeptics’ claims, a different kind of propulsion, not limited by the available sunlight, must be used, and it is difficult to make any of the current technologies light enough for an airship design.

The record altitude for a balloon is 170,000 ft, winzen research balloon.

So they need to get better propulsion or launch something small and light that has less drag. close the 44 fold difference between propulsion and drag.