DAVID G. ULLMAN
Comparing Air-Taxi Visions
A simple analytical model is used to estimate range based on type of vehicle, battery characteristics and number of passengers. Accuracy of the model verified by comparing its results to other models and limited real-world data. The model is used to compute air-taxi potential for VTOLs, rotor-craft (helicopters and multi-copters) and USTOLs (Ultra-Short Take Off and Landing) craft.
Electric rotor-craft such as the eHang 184 and the VoloCopter 2X have very limited range even with next-gen batteries.
VTOL aircraft need to be very large to be effective (UBER is focused on 5000lb machines). Further, the high power needed, as with the rotor-craft, imply inefficiencies that may not be overcome with any foreseeable batteries and sound levels that may be unacceptable.
USTOL aircraft have high potential. They are perhaps the least developed of the three classes considered but can operate on near future batteries and very small “pocket” airports.
Clearly the use of batteries for air taxis is problematic. Even next-gen batteries are limiting. Other forms of energy storage need to be explored and developed.
It is possible to use a fairly simple model to compare and contrast different classes of air vehicles without getting caught up in the details.
A full description of the equations used and a spreadsheet version of the equations is available. Contact Ullman using the contact form to request these.