Autonomous flying personal transportation -- "the flying car" -- is becoming real. I have written previously about some of the issues such as noise, energy efficiency and "sky pollution" but it's clear that the engineering problems are being solved.

Solving those other problems is a challenge, but I can be more confident in predicting that in the 2020s, many ambulances, police, fire and military vehicles will be based on multirotor technology. This will be particularly true in more rural areas or areas with limited roads.

The air ambulance seems an obvious win, at least for some cases. A small number of air ambulances in a city will get one to you in under 3 minutes, and likewise be able to get you to the hospital just as fast. So fast, in fact, that it might be a better choice to get you to the hospital in 3 minutes with no paramedic to attend to you than to have it take 12 minutes in a big van with all the gear and team. While you fly above the traffic, the traffic will be happy you aren't disrupting it either.

Down below I will talk more about the technologies, but let's begin by looking at the issues of the flying ambulance.

The flying ambulance

There are a few key issues with the air ambulance right now. Pure electric multirotors, like the volocopter shown in the picture, have a payload of about 400lbs. That's not enough (especially with some patients) to also carry a paramedic and all the gear they might want to treat you on the ground and during the trip, and certainly not a pilot as well.

The pilot can be removed through automation and remote operation/supervision for the landing and takeoff. The people and gear to treat you at your site can arrive in a 2nd vehicle -- in most cases there's no reason you can't send as many as you need.

While in the air

How can the patient get the best care in the air in a limited payload vehicle? Every single machine and drug weighs more than we would like. You could have modular packs and place is only those that are needed, but that takes time. The hospital may only be 2 to 3 minutes flight away, and it will easily take that much time to reconfigure the gear.

You could make robotic trauma gear -- a robot that can inject a wide variety of drugs into a line inserted on the ground, with an array of sensors and monitors, but once again, putting this on could take more time than getting to the hospital, though the hospital also wants those things to be in place so it may not be wasted time. Such gear is not going to do things like put a ventilator on a patient or clear an airway.

One could imagine, for a few years, creating a special professional category of emergency medical responder who weighs as little as possible. Chances are that women would dominate this profession. They might be actual emergency doctors, not just paramedics. Today, it is judged inefficient to have full MDs in ambulances as so much of their time is spent in travel. That might not be the case with the flying ambulance. In any event, it's possible that a premium service for the wealthy which offers a flying ambulance with trauma MD on board will develop. That's because a single doctor could get anywhere in a 5 mile radius (80 square miles) in under 10 minutes, and get you to hospital even faster.

Big strong paramedics

Unfortunately, while an in-air paramedic should be light, many emergencies require the opposite -- big strong people able to lift even a heavy patient onto a gurney or even down stairs. As long as this is known in advance, those stronger people can arrive by ground or in a 2nd flying car. They don't necessarily need to return by air.

Landing

Landing anywhere is a big challenge for these vehicles. Ambulances could be allowed to land on the street, blocking traffic, which could help. Otherwise they may not fit in the typical parking spot or driveway. Many such zones are full of overhead wires and trees, and not safe for landing even with a human pilot. If they have to land a block away, they would need a way to get quickly to the address. It may simply be that some addresses are not suitable for air ambulance service and a road ambulance has to come. (The road ambulance might well drive you only a block to where an air ambulance waits for you.)

For the hybrid vehicles (which do not have the limited operating time of the pure battery units) another option is to carry a medical pod on a cable, and not to land. Just lower the pod and hover. The pod would have electric motors and a small battery -- possibly left behind and collected later -- to travel a block or two from the suitable drop-off point.

This would be noisy and disruptive, but any ambulance arrival is already like that.

The other issue is extreme weather and high winds. These vehicles are going to be quite limited in that situation. Ground ambulance will need to continue to exist for these times.

Flying Cops and Fire

Police fast response by flying police car is an easier problem to solve, and thus more likely. The police vehicle can land further from the destination and the fit police can run or even bicycle where they need to be. If it's an incident with an armed suspect, they probably don't want to fly too close anyway. Any urgent police call could have an officer on scene in just a couple of minutes.

Fires are more challenging. You could send a firefighter with hose, but there may not be a lot they can do. The vehicle, if landed, could repurpose its power source and some of its motors into pumps. When the fire truck arrives it can contain batteries to swap for the return trip. Many fire calls are for fires inside, where a couple of firefighters with skill, extinguishers, fire suits and a ladder might be able to do a lot before the trucks arrive.

The Technology Players

Most players are attempting to build electric multirotor vehicles -- effectively big versions of the small drones that are everywhere. This needs big powerful motors and big blades and lots of them to get the lift needed to carry 1-2 people. The problem is the batteries. They weigh about 6 to 7 kg per kwh of energy. Every kg you add to the battery pack increases the weight of the vehicle, so you get diminishing returns. You can't just double the battery and double the range.

The Volocopter, pictured above, is an example of a pure electric vehicle. It is as small and light as they can make it, and the range is fairly limited at 27km. That's still pretty useful for a lot of things, though if you have to take a few hours recharging after a flight it's less useful. Battery swap can save the day.

An alternative is a hybrid design, with a liquid fuel (gasoline) motor powering a generator to run electric motors. You need electric motors to provide the dynamic response that has made the drone revolution happen. You wants some batteries for power surges and also to get you down if the generator fails. A regular helicopter has big blades that will turn even without the motor if it is descending. This is called auto-rotation and allows a helicopter to (roughly) land if the motor fails, though it is far from easy. No such luck with the multirotors. They tend to have lots of rotors and independent batteries, so they can survive the loss of a small number of motors, rotors or batteries, but if they need a generator to fly and the generator fails, they are going down -- unless they have just enough battery to make it down.

The Workhorse Surefly which is also pictured above. Their design is not autonomous at all, it needs a pilot -- but it's also quite a bit less wide than the Volocopter.

Bell Helicopter is also making such a vehicle, with 4 seats, but it won't release details on quite what it will be, other than a hybrid design.

One alternate design, found in some unmanned "crane" drones, has the gasoline motor power a large rotor for the main lift, and then has a generator power small electric rotors for the dynamic control and stability. If such a vehicle loses the gasoline motor, it can't survive, even with some batteries. That's why this design is used for unmanned cargo vehicles for now, and a parachute is added to avoid a nasty crash. One Russian design is using this model, aimed at moving cargo in remote northern areas where there are few roads, or out to offshore platforms.

Even Boeing is getting in on it with their prototype.

Energy use

No question, electric hovering takes a lot of energy. My estimate is that even the best devices probably take 6x to 8x more energy to travel than a small electric car would. They make up for it by flying in a straight line while the car has to take the road network. In a world trying to reduce our transportation energy usage, there will be controversy over moving to a wasteful form of transport in the city, at least for people though not for emergency vehicles.

One option is to have a vehicle that can do the vertical take-off and landing of a multirotor, but switch to flying with regular big fixed wings like a normal airplane. Such vehicles can get closer to ground vehicles in efficiency. This design is already favoured for small delivery service drones. The presence of big wings makes VTOL more difficult for a passenger vehicle.

As I've written before, the right answer might also be to have short range vehicles -- including robocars -- take you to a short airstrip or heliport, where you then quickly transfer to an efficient flying vehicle, be it fixed wing or rotor based. It will fly you to another airstrip or heliport, and from there a robocar or short range electric copter could complete your journey. If the vehicles are automated, they wait for you, so the transfers are always fast and easy.

The Timeline

The most basic vehicles are flying now. Big players are getting into the game, including several stealth companies with heavy backing, like the Kitty Hawk Flyer and others. While this will not come to the world quite as quickly as robocars, don't expect it to be too far behind.