Jan. 24, 2023, © Leeham News: “For those of you old enough to remember, this is the Jetsons. This is the dream. This is what everybody would love to do.”
This cartoon is what former Boeing CEO Phil Condit used to segway into the hot topic of Urban Air Mobility vehicles (UAM). A cartoon is an apt illustration of UAMs.
You walk out your front door, climb into the vehicle, and off you go. “All of a sudden, it looks like you can do that,” Condit said. Condit made his remarks on Jan. 9 at the University of Washington aerospace class.
There is a concept called Air One, a battery-powered two-place UAM that has folding wings and a folding structure for the rotors. It fits in the garage. It uses a landing pad in front of the house. “This is a step to the Jetsons. What’s the problem?” Condit posited. “Well, there are a number of them.”
The advertisement shows Air One has 771 horsepower and a 96nm range. Reserves aren’t mentioned. A competing concept called Icon A5 shows 100hp, a range of 427nm, and a 45-minute reserve. This has wings to carry the lift. “Taking off vertically is not cheap. Wings are way more efficient than vertical lift.”
Condit pointed out that Air One suggests you could fly to a favorite fishing spot. But, Condit said, “unless your fishing spot has a charging port, I’ve got two vertical take-offs and two vertical landings. I have a net effective range of 30 miles. So, your fishing spot has to be within 30 miles.”
The biggest problem, however, for the Jetsons is Class B airspace governing air operations near airports. Air Traffic Control compliance is required in Class B air space. “If I’m going to fly in that general vicinity, I’ve got to be really capable.” There are minimum altitudes, visual flight and separation rules, and other requirements special to Class B air space. “Do I really want to have several thousand of these zipping around?” Condit asked.
“Can it be? Yes, there’s no question. Should it be? That’s a much bigger question.”
Condit said the challenge of the plethora of eVTOL and UAM concepts isn’t whether they will work. The challenge shifts to the ground operations—the vertiport. With most of the concepts seating fewer than 10 passengers, the transportation limitation is huge. A vertiport with eight parking spots can serve around 400 passengers a day.
“There are about 600,000 people who commute into New York City every day. If I want to touch 10% of them, that’s 60,000 people. If I’m going to do that with these vehicles, I need a lot of landing spots. There are four in New York,” he said. Rooftops currently are cluttered with HVAC equipment. But if the roof is available, a building with 5,000 people in it can be served by eVTOLs and UAMs at the rate of about 45 people an hour.
eVTOLs flying from New York City to the three commercial airports serving the region will transport about two-tenths of one percent, Condit estimated. Airlines can offer this as a premium service, but “is it really urban air mobility?”
If eVTOLs and UAMs are at one end of the spectrum, supersonic and hypersonic transports are at the other. Boom Aerospace proposes the Overture 80-passenger SST, a concept that has drawn wide skepticism among observers and experts. Unable to persuade GE, Rolls-Royce, Pratt & Whitney and Safran to design an engine for the airplane, Boom put together a group of three companies to do so. None has designed and built an engine anywhere near the 35,000 lb thrust category needed for Overture.
Condit is on the Boom advisory board.
“Technically, [Overture] is very achievable. The issue is economics. It will burn more fuel. Boom said it will be 100% Sustainable Aviation Fuel (SAF). SAF is more expensive than Jet A fuel. Can you get passenger demand to make it interesting? I think the answer is probably yes.”
Condit predicts that the current prohibition of supersonic flight over land could be modified to noise regulations at levels that will allow Overture to fly over land. “If that happens, then supersonic gets interesting.”
Hypersonic transports at Mach 5 are a much tougher challenge than the SST. Condit sees hypersonic as a “really tough problem” to come to successful development.
Condit believes some eVTOLs will come to market successfully, and possibly some hybrids. The SST would be a premium product. He believes Boom’s group of three companies to design and build an engine is possible. It will be a long time before hypersonic airplanes emerge.