"So how goes the Project?" Ranna asked. Her hand strayed to her eyepatch absently pulling her hair in front of it.
"It goes," Jorge said lifting the taxi and flying towards her apartment. After a second he turned on the meter.
"We should make it look good," Jorge said looking apologetic.
"Did you guys lick the resupply problem?"
"Yeah. Without lifters." It was tough considering the derelict they were refabbing was in the middle of nowhere, stuck in the middle of an arid waste and broken terrain. He concentrated a moment on avoiding some power lines and continued, "We started using auto-gyros what you call Dynocopters ... they could carry supplies and land in 30 meters or less. Not quite lifter technology but pretty neat anyway."
"I told you we build good vehicles here. It's all the chrome piping we stick on the sides. Makes our stuff go faster. "
"True. When we want a buzz copter or roadster to go reeeeally fast we stick a bigger gas pedal on it. That's science!"
"What was your area of expertise when you were a Tech Knight?"
"Worker safety conditions."
" ... okaaay."
Jorge regarded another aero moving ahead and off to the right annoyedly as it was going to cut across his nose. He blew the horn angrily to no affect. The aero had police markings with a two man crew. Ranna peered at it a second and said, "Those aren't cops! Peel o ..."
One of the 'police' displayed his true nature as he pulled an automatic rifle from the cockpit and fired a long burst. Jorge was already veering hard to the left. The maneuver threw him against Ranna. The bullets zipped around them. Ranna drew a revolver from a coat pocket and began firing rapidly. the police aero struggled to match their turn.
"Rifle ... under the seat," Jorge hissed through gritted teeth. Ranna stopped fumbling for a speed loaders and grabbed the weapon under her. It was a compact offworld design and she hunted to find the safety and bolt to ready it.
The attacking aero had pulled almost into their tail when Jorge dipped his flyer's nose and decelerated hard. Ranna hung onto the rifle and trusted her seatbelt. Jorge had installed them after all. The assassins pulled ahead and above them and Ranna held a steady stream of fire on their aero. She was rewarded with sparks and smoke from the fuselage.
The aero pulled into a climb and began turning away back the way it came. Ranna hurled bullets and obscenities after them until she emptied the rifle.
"Hah. We showed them eh?" she crowed watching them flee. She gave Jorge a jab in the arm for emphasis, really proud of her shooting if nothing else and already trying to make up a scheme to legalize her new found toy. Perhaps the imminent domain clause ... Jorge gave a low groan and she turned her good eye to him.
Jorge was gripping his right shoulder where a widening red stain had appeared on his uniform. Still gritting his teeth he threw a few switches and the flyer began to slow down and drop. He looked at her and asked, weakly, "Can you fly?"
"Uh hello, no depth perception. I never went for flight school ... let me see it." She peered at the wound and quickly pulled off her scarf, padded it and pressed down on the bullet hole. Jorge winced.
"It's okay. You can take it, love. Just get us down."
"... can do ... love," Jorge smiled a little bit at that as his head began to fall forward towards the dash. Ranna grabbed for the stick convinced even with one eye she'd do a better job than him now.
"You don't think I'd let just any strange man rub my feet, did you? I am a lady," she said.
There was no reply.
Lifter technology is the semi-respectable cousin of reactionless drives. They assume a fifth repulsive force will be discovered. That is no longer as crazy as it sounds what with dark energy accelerating the expansion of the Universe. Unlike reaction drives, which work by throwing crap out the back of your vehicle very fast, a lifter functions by pushing against the planet or other massive body (presumably) below you. In effect the planet becomes the reaction mass of your vehicle. Even Tom Swift used this dodge to avoid the high propellant tax of a rocket.
(Cover courtesy of Project Rho: Tom Swift's repulsor driven craft: the Challenger!)
Lifter craft are more stable than helicopters and just as maneuverable. They also don't suffer from prop wash though the repulsion force can hurt you if you stand directly under one that's at low altitude. Inverse square law is your friend here.
(Insert table on ground pressure)
Generally speaking a lifter can fly you at least 30,000 - 40,000 kms. or operate a week to ten days before needing a recharge. Lifters have their limits. They can get you to orbital altitude. However this takes a number of hours, much longer than a conventional spacecraft (and merchants consider time = money). More to the point their ability to produce lateral thrust is limited to a top speed which is way below orbital speeds. Hundreds of kph in general. I'd say that normally those several hours are required to get you to low orbit though, a few hundred kilometers and anything beyond that is for people trying to get into the record books.
As an option you might link top speed to world size. An air raft can make 400 kph. You could say the speed of that type of vehicle is 50 kph x UWP size code. So that air raft would make 500 kph on a size A world but only 200 kph on a Mars sized world. This might be another reason to keep earlier aircraft around. They're faster! Other types of lifters can be treated the same way: top speed x (UWP Size Code/8).
That last part is important. You can get to orbital height but you will not be moving at orbital speeds. A ship trying to rendezvous with you will have to kill its speed or you will make like a bug on its windshield. Worse actually. it won't do the poor ship a lot of good. Keep in mind an object moving at 7 kps has kinetic energy equal to an equal mass of TNT. Bits of wire, specks of paint are all orbiting that fast. Now consider yourself in a spacesuit (most lifters are not vacuum tight. If that doesn't give you the chills consider yourself in a spacesuit while a wise guy throws paper airplanes at you, that have their tips soaked in nitroglycerine.
If that still doesn't scare you go watch The Conjuring I & II and Annabelle.
Lifting to orbit is clearly a desperation move. For planetary evacuations and such. I've seen lifters failing after ten diameters in some versions of 2d6 games. That would make them work at environments with .01 gee to push against. YMMV if you want to figure out planetary density and local gravity fields. I go with the tradition volume = mass of the classic space opera games (mostly).
This means belters and their ilk aren't going to have much use for lifters and will replace them with reaction drive craft or better yet mining bots. It also means all that interesting infrastructure like orbital towers and transfer bolas still have their place.
Lifters are introduced at TL 8, an era of late interplanetary travel where they piss off the rocket engineers (who've been working hard to make reaction driven single stage to orbit vehicles economical.) They cause a huge dip in your rocket corporation stick until people try bringing stuff into orbit and wind up getting shot full of holes (or just one big hole) or a power failure shows them they'd have been better off investing in a heat shield and a gliding body just in case.
Lifters do provide an enormous boost (see what I did there?) to reaction drives. A rocket with lifters can negate gravity's attraction and use almost all of its thrust to achieve the desired velocity (atmospheric drag still cuts into some fuel use). The trick is having a lifter/power system that is light enough to be worth it for the more anemic rockets. It doesn't have to be less mass less than a similar engine and propellant because you can reuse the lifter system.
A ship can take off, from Earth say, at one gee, negating gravity and arriving at orbital speed in about 11 minutes of steady thrusting. Most people can handle 2 gees of acceleration even without compensators for this amount of time.
(Zaonian 'hooligan aero' in use.Why that looks like Wardenclyffe back on Old Earth. Parallel development is amazing! Picture courtesy of Raymond McVay of Blue Max Studios. Ray also does commissions.)
I've set up at least one world where people have used Tech Level 5 vacuum tubes and early transistors to duplicate lifter technology. My justification was that the experiments that discovered the repulsive force required high tech laboratory gear to detect. The actual gravity modules (or whatever) could be duplicated using earlier technology once the principles of the repulsive force were learned. Most people didn't try in my setting for a couple of reasons 1) lifters could be imported easily enough from a higher tech planet and 2) they required other TL 8 technology to be truly economic: energy storage systems.
A lifter uses a lot of power, at least as much as a modern battle tank. TL 8 batteries or super conductor loops or flywheels or what have you can power a liter for a week or more. The primitive batteries used by the Zaonians, even their state of the art lithium ion batteries, can barely power aeros for a few hours. Lifting capacity is also halved or quartered (one or two man crews). Airplanes and helicopters can carry more and are cheaper (and don't explode like some prototype batteries.) The aeros' lateral thrust is also managed with fans, not the lifters.
All this makes Zaonian aeros impractical, noisy, hard to handle, and wicked cool to people who like this sort of thing.