Eureka! Mary Sue has just finished her unobtainium-based levitation engine that should be able to deliver payloads to orbit for less than the price of a Tootsie Roll, and will allow her to start operating her own space agency! She's ready for her first test flight to make sure it's all working, but --

Well, you see, she's not sure she wants the government (EDIT: or anybody, really) muscling in on her little operation. She should have some sort of cloaking device rolling out of the old noggin in a couple months or so, but by golly, she wants to go to space now.

Assuming that the maneuverability of her modified family car is limited only by the squishiness of the pilot and the detectable power signature of the engine itself slightly less than the average toaster that you forgot to plug in, what kinds of altitudes can she levitate to without drawing the government's attention? How fast can she set the throttle? How many test flights should she consider safe (either from detection or to consider the engine a success)? Is there any particular places she might go to make it easier or harder to avoid detection? What about when she's ready to call it all good and make the leap to orbit? Is there any way to do this covertly from Anytown, USA?

A perspective on how different techniques might appear to the government if they do get noticed but not red flagged would also be welcome.

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – L.Dutch
    Commented Nov 29, 2018 at 8:47
  • $\begingroup$ An Invisibility Booster? $\endgroup$ Commented Nov 29, 2018 at 20:08
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    $\begingroup$ Just wanted to say I loved reading this question, you got a few chuckles out of me :D squishiness of the pilot lmao! Have you written any stories? I would love to read them! $\endgroup$
    – sǝɯɐſ
    Commented Nov 29, 2018 at 20:30
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    $\begingroup$ This has been so much fun, I'm not sure whether I should bring up the fact that I accidentally pulled a bait-and-switch on myself. This was originally intended as a setting for a role-playing game taking place in the present, and I mocked up Mary Sue as a stand-in for the players, since parenting prevents me from actually running the game at present. Then I had so much with Mary Sue, I forgot where all this started, and that I have no idea whether any eventual players will go for stealth or publicity, and I want to be ready in case they try to avoid detection. $\endgroup$
    – Trevortni
    Commented Nov 29, 2018 at 23:28
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    $\begingroup$ If her family car is a ford angela, she can say she is on a Harry Potter set and people dont mind the flying ford angela. $\endgroup$ Commented Nov 30, 2018 at 3:19

16 Answers 16


If you fly, everyone is watching

Unfortunately for anyone trying to hide flights from their government, a relic of the attitudes of the cold war means that all nations keep very close track of anything moving through or approaching their airspace. This helps with air traffic control, who also like to keep very close track of the airspace they're responsible for.

Well, that's if you fly over land anyway.

What Mary Sue should have done is build a flying boat

There's a lovely place deep in the Pacific Ocean known as the Oceanic Pole of Inaccessibility, it's the point furthest from any point of land anywhere in the world. There's not a lot going on down there and it's probably the safest place to make a space launch without being caught.

On the other hand, it's probably absolutely swarming with nuclear deterrent submarines hiding from each other while having exactly the same idea, so in practice you're probably better going somewhere a little less obvious. There are fairly standard shipping lanes to avoid, mostly following the great circle path between major ports. Fishing fleets have no interest in deep water as there's no fish out there. You'll be out of detection range or out of jurisdiction of most interested parties.

All you have to do initially is keep your speed within the capabilities of modern aircraft in case anyone does spot you on radar.

Realistic option

The problem, as you've probably already realised, is that this is too big a step for an unsupported individual to take. Unless she already has a company of her own that has a strong enough position in the market (See Stark/Wayne Enterprises), she has neither the financial backing nor the industrial base to make something practical out of her discovery.

Mary Sue she may be, but to do this alone she needs to be Richard Branson, Bruce Wayne, Elon Musk, or Tony Stark. SpaceX and Virgin Galactic have the rest of the hardware, they could just drop her engine into an already built space vehicle and you're away.

Land it on the front lawn at Virgin Galactic or SpaceX and ask to speak to the boss. They're not going to take you seriously until you land on the lawn as they probably get a lunatic a week making such claims.

How you handle the patents, IP and licensing isn't good for a story as it's a bout of endless legalese but that's the only way anything is going to come out of this before she dies of old age. Remember it takes more working hours than the working life of one person just to build a commercial jet, and she wants to build a spaceship.

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    $\begingroup$ This very much depends on where you're flying. If you're in the approach/departure zone of a tower-controlled airport, ATC radar will pick up things like hang gliders and flocks of birds, and tell you about them. OTOH, if you're flying at fairly low altitudes around say the Black Rock desert or Idaho backcountry, you probably won't appear on anyone's radar, and if you do they won't care. $\endgroup$
    – jamesqf
    Commented Nov 28, 2018 at 18:51
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    $\begingroup$ Do a deal to take a percentage of all profits based on your technology - they'll just report zero profits (see "Hollywood accounting"). $\endgroup$
    – Kreiri
    Commented Nov 29, 2018 at 10:37
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    $\begingroup$ One can't seriously think of public display of such innovations if the intent is to keep ownership. If it is really an earth-shaking, mind-blowing stuff which does what OP stated it does, then in no way any government will play by the rules. And if Mary Sue will insist on her rights.. you know, there are accidents in this world. And people die in such accidents sometimes.. $\endgroup$
    – Alma Do
    Commented Nov 29, 2018 at 11:42
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    $\begingroup$ @AlmaDo, Why shouldn't the government play by the rules? Have you seen the budget for the military? They would have no problem paying a fair price for this and giving her a well paid job for life helping develop it, as they usually do with anyone who comes up with something significantly beneficial, life isn't a conspiracy thriller. $\endgroup$
    – Separatrix
    Commented Nov 29, 2018 at 11:49
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    $\begingroup$ @AmiralPatate, starting a little company and getting bought out for vast sums of money is the whole point of the startup industry right now. The big players have vast sums of money to throw around specifically for this sort of thing. It's much quicker, easier, and importantly cheaper, to just pay the money above board than to play dirty. $\endgroup$
    – Separatrix
    Commented Nov 29, 2018 at 15:38

She should build an airplane around her car.

Fortunately for suicidal hotheads everywhere, the FAA has a special X (experimental) category for people that think it'd be neat to build an aircraft out of whatever they have lying around their garage.

Sure, some old retired aviation buff who whiles away the hours watching the old cornfield airstrip might notice something just ain't quite right about Mary Sue's bird, but he's just an old crank.

If you really want to make things exciting, fly it around inside thunderstorms. May void warranty.

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    $\begingroup$ A quick glance at the link suggests that going this route might require some sort of inspection to determine flightworthiness, which would be contrary to Mary Sue's goals. Still, she did write a super AI last month; maybe hacking a fake certificate might be possible. But even then, what happens when this experimental aircraft registered to a fake address suddenly veers out of the stratosphere? I doubt there's any staying out of the news then. $\endgroup$
    – Trevortni
    Commented Nov 28, 2018 at 17:32
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    $\begingroup$ It's a good point, @Trevortni -- she'll want to build a real X airplane, get it certified, then hollow it out. $\endgroup$
    – Roger
    Commented Nov 28, 2018 at 18:55
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    $\begingroup$ @Roger I'm pretty sure by that time her cloaking generator is finished. $\endgroup$
    – Suthek
    Commented Nov 29, 2018 at 13:32

unobtainium-based levitation engine

Hint : H G Wells.

But once you start invoking "unobtanium" the question arises as to how in blazes all the scientists looking for stuff like this missed it, but your protagonist found it on her own.

will allow her to start operating her own space agency! She's ready for her first test flight to make sure it's all working, but --

  • Does she also have a method of navigating ?
  • Breathing ?
  • Eating ?
  • Drinking ?
  • Handling human waste products ?
  • Dealing with life in zero-gee ?
  • Keep the craft's temperature regulated ?
  • Not being irradiated ?
  • Not burning up on return ?
  • Somehow converting levitation into a controllable thrust ?
  • Build a craft which won't suffer failure - because everything can fail ?
  • Or just throw the dice and hope it all works without problems ? (didn't work for anyone else).
  • Has a backup plan ?
  • How to communicate ? Needs a lot more than a radio.
  • Who to communicate with ? Needs a lot of infrastructure back home.
  • Power system for the craft ?
  • Space suits ? These are really a lot more complex than people understand generally. They're almost mini-space ships on their own.
  • Money - she'll need loads of this !

And these are but a fraction of the practical problems faced by any space craft, regardless of propulsion method.

Well, you see, she's not sure she wants the government muscling in on her little operation.

They're going to get awfully suspicious when she tries to use or build her own worldwide communications network, I can tell you that for nothing.

At best every intelligence agency on Earth (all of them) would be monitoring all the money flows and activity and resource movements. If they don't know what it's for they'd be even more suspicious - that's their jobs, and if they figure out what it's for they'll get very, very directly involved.

In the modern world hiding is impossible. The more you try to hide, the more suspicious you look. Encrypt your emails ? The equivalent of putting a neon sign up saying "I'm up to something very suspicious".

She should have some sort of cloaking device rolling out of the old noggin in a couple months or so, but by golly, she wants to go to space now.

A character like this would be dead on the first flight, because impulse driven and getting back from space alive are incompatible. The first astronauts were chosen not simply for bravery or skills, but because they had almost unbelievable levels of self discipline and willpower and particularly calm decision making skills in even the most extreme crisis. "Golly she wants to go into space now" types would be dead so fast from the huge number of things their impulse driven personality did not plan for, that the book would be a short story.

Assuming that the maneuverability of her modified family car

A modified family car would be about as likely to survive the trip as the idiot who got into it.

And just how well will Mary Sue react to being trapped in a family car seat (in a space suit) with no place to go during the trip. Astronauts are also chosen for this kind of mental capability - not at all trivial.

The idea makes H G Well's fantasy trip sound rational and well planned. Modifying the family car is something Disney would be embarrassed by (not that this would prevent them selling it).

is limited only by the squishiness of the pilot and the detectable power signature of the engine itself slightly less than the average toaster that you forgot to plug in, what kinds of altitudes can she levitate to without drawing the government's attention ?

Levitating and the government are not the problem. Staying alive is.

In principle, however, modern radar would not detect her at this size. It's quite hard to detect an object without a transponder, particularly a small one.

How fast can she set the throttle ?

How many gees can Mary Sue and the "modified family car" (!) withstand. Not many. For how long will this acceleration be maintained ?

Has Mary Sue heard of the sound barrier ? Aerodynamic forces ? The way high speed supersonic aircraft surfaces heat up due to friction with the air (even at high altitude) ?

Mary Sue - first woman to levitate herself into the Darwin Awards.

How many test flights should she consider safe (either from detection or to consider the engine a success) ?

How many car trips would you consider "safe" ? Because it's always the next one that the accident occurs on. There's no safe, there's only calculated risk. How much risk does she consider acceptable ? If I told Mary Sue there was a 10% chance of dying would she be OK ? That's what a well designed, carefully tested, full fledged space program might manage.

In a "modified family car" (seriously does that sound insane as you read it ?) the odds of a successful flight are, IMO, as close to zero as makes no odds. The materials are simply inadequate to the task, and the base structure is not suitable for aerodynamic loading. Break up during first flight, I'd say.

But "Golly, she wants to go to space now.".


Is there any particular places she might go to make it easier or harder to avoid detection ?

She should go to school, maybe try for a university. Maybe the library if that's not possible. She could desperately do with reading every book on physics and engineering she can.

No place is not covered by satellites. Space is monitored in case, e.g. someone launches nukes at someone else (about the size of a family car you say, she'll probably trigger WW3 ).

What about when she's ready to call it all good and make the leap to orbit ? Is there any way to do this covertly from Anytown, USA ?

Only in X-Men comics. In the real world when you land the entire world will be awaiting your return. And they won't be happy. In the USA the different agencies would have about a million arguments between themselves about who gets to jail you first. You'd never get to see a lawyer.

A perspective on how different techniques might appear to the government if they do get noticed but not red flagged would also be welcome.

Unauthorized use of airspace leaps to mind. Spying is an option. Possibly unsafe use of a motor vehicle or illegal parking if she's not real careful. No pilots license ? No flight plan ? Uncertified aircraft ? Possible anti-terrorism laws ? Surveillance of military installations (did she look down ?) ? Illegal entry into a country ? (careful where you land, Mary Sue). Triggering WW3 ? Failure to file taxes ? (you did say she was trying to hide)

And what if the Governemnts already have unobtanium hidden in their secret labs ? Black Helicopter time, methinks.

But the thing is, Governments would have one view that involves Mary Sue's permanent placement in a gilded cage in a really secure military facility while she "helps them".

Even in the extremely unlikely even Mary Sue survived a single test flight, let alone a real trip, Mary Sue would disappear off the face of the Earth.

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    $\begingroup$ You raise a lot of good points, and "impulse driven and getting back from space alive are incompatible" is definitely one of them. (It's bad enough being impulse-driven and in an atmospheric aircraft, let alone a spacecraft.) However, as much as you do, I can't in good conscience upvote this as a good answer to the OP's question on how to keep the government from detecting the "flying car". There's a very much implied "you can't, because of all these reasons", but I don't see you explicitly providing an answer. $\endgroup$
    – user
    Commented Nov 28, 2018 at 18:30
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    $\begingroup$ We don't ask how Mary Sue does these things, it'll just set her off, and she's insufferable at the best of times. $\endgroup$
    – Separatrix
    Commented Nov 28, 2018 at 19:29
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    $\begingroup$ "... burning up on return ... structure is not suitable for aerodynamic loading. Break up during first flight, I'd say." No. If you have an unobtainium-based levitation engine that dissipates less power than an unplugged toaster, you don't have to go fast. Orbital velocity in particular is not necessary. $\endgroup$
    – Hugh Allen
    Commented Nov 28, 2018 at 23:29
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    $\begingroup$ This doesn't really answer the question. The question posits that somehow, someone was able to build a spaceworthy vehicle out of common materials. Given that, how can they conceal it without some other technological breakthrough? I certainly wouldn't like a story that presented this as scientifically plausible, but you can say that it's all done through sorcery if you'd prefer; the basic question is how to conceal this magical space-craft. This answer mainly just criticizes the scientific accuracy of the idea, which I doubt was ever really in question even to the poster. $\endgroup$
    – Obie 2.0
    Commented Nov 29, 2018 at 5:15
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    $\begingroup$ @StephenG, you're missing the importance of the big lies and the little lies, we accept warp drive but won't accept someone wearing a wristwatch in the wrong period. You can gratuitously handwave artificial gravity, but you can't make small changes to thing everyone is familiar with, and everyone knows that if you fly in controlled airspace all hell will break loose. The question addresses only that aspect by use of Mary Sue and Unobtanium to fill the other gaps. $\endgroup$
    – Separatrix
    Commented Nov 29, 2018 at 11:44

This depends on two factors - where Mary's launching site is located and how her flying car is designed.

First concern would be eyewitnesses. Anyone seeing a car flying would undoubtedly be alerted and would try to snap a picture of it. Thus, she can't fly during the day in an area that has any noticeable population.

Second concern are radars - both military and civilian. Without any stealth technique applied, Mary's car will have a radar cross-section similar to a small civilian airplane. However, good news is that radar operator can't know it's a car. So, unless Mary is entering some restricted or regulated airspace (i.e. an airport vicinity), her car would likely be dismissed.

Third concern is detection in space. A car on low Earth orbit would be visible from a smallest telescope. With a better backyard telescope, a clean picture can be taken. And there are just too many telescopes peering into the sky, taking just one lap around Earth may get notice from someone. If Mary can solve temperature management in space, she can paint her car all black, lowering its albedo and making it harder to detect. Solving infrared signature problem may be more difficult, but number of instruments working in infrared spectrum is orders of magnitude lower than visible ones.

With basic precaution and little extra engineering, Mary can safely fly into the space.

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    $\begingroup$ There is plenty of controlled airspace well away from airports. In some areas, all you need to do to enter controlled airspace is to get a few thousand feet above ground. The good news is, it's easy to know what airspace you need to avoid; just get a few aviation sectionals and/or related airspace documentation (which is readily available), and learn to read them. Mary could probably even take a general aviation navigation theory class for that part (she is, you see, very interested in realistic simulator flying). $\endgroup$
    – user
    Commented Nov 28, 2018 at 18:21
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    $\begingroup$ On the second point: only as long as it's doing general aviation like things. A transponderless Cessna-like radar contact at 60 000 feet and climbing is going to be raising some eyebrows... (Especially since you're supposed to be controlled above 18 000 ft) $\endgroup$
    – tylisirn
    Commented Nov 29, 2018 at 13:46
  • $\begingroup$ @tylisirn yes, good point! Although radar coverage outside major airports and military facilities is rather poor, something flying at high altitude would not be dismissed. Mary needs to pull farther into countryside when climbing or descending. $\endgroup$
    – Alexander
    Commented Nov 29, 2018 at 17:28
  • $\begingroup$ The radars are going to notice that the car is doing some very strange things that light aircraft cannot do. While the car won't have a transponder, it will clearly be ascending vertically (ATC will estimate height by comparing ranges between different radars core.ac.uk/download/pdf/80112153.pdf). $\endgroup$ Commented Dec 1, 2018 at 12:18
  • $\begingroup$ @Paul Johnson not sure about Europe, but in US civilian radars currently don't use triangulation. $\endgroup$
    – Alexander
    Commented Dec 2, 2018 at 1:57

Generally speaking, airspace monitoring is transponder based. For the most part, if you are not broadcasting your presence people won't know you are there. There are exceptions where real radar is used, but that is generally the realm of military rather than civilian control. Point being that as long as you are staying away from areas where the military would have an interest, you are unlikely to be detected or noticed on radar.

That would be to avoid coastal & border regions, particularly those where anti smuggling operations are likely. Next up avoid military bases, particularly those with airfields and/or significant strategic import. The people around those tend to be pretty suspicious and are much more likely to maintain an active radar watch. Also keep the altitude down, the closer you are to the ground the less effective a radar system is and the more likely you are to be dismissed as noise or something mundane if you are detected.

Next up would be to avoid population centers. Particularly for your takeoff & landing stages. Find the satellite maps that show night time light patterns, and go somewhere that is dark. Fewer people in the area means smaller chance for some random person to be looking the right way with a smart phone handy and having a video of your car zipping along above the trees show up on YouTube. (Of course any such video is almost certainly going to be debunked as a hoax or conspiracy theory, so why worry about it...)

Finally, find someplace where the terrain favors obscurity. Mountains play hell with most detection systems and running initial tests in a remote valley, making sure to stay below the tops of the surrounding ridges, will improve your odds significantly. Likewise, starting in the bottom of a canyon and staying below the rim would have pretty much the same effect.

The thing that is much more likely to trip you up is satellite monitoring. However, most countries don't put a lot of resources to analyzing imagery from within their own boarders. They are much more concerned with the goings on elsewhere. That said, satellites can be tracked, and with some effort you should be able to define windows where your target test area is free from observation.

The risk there is that satellites can be moved, which changes the observation windows. However, I suspect that one could dive into the dark web and find an organization dedicated to tracking satellites and more importantly, watching for such changes that might catch you off guard. It seems like something a lot of people up to no good would be worried about.

If you are detected by satellite, it is likely that it would be a foreign government that does so, and they are much more likely to assume that it is some black research project of the local nation and direct their resources in that direction than they are to come looking for a wild break through by an individual.

Another note for evading detection would be to do something to disguise that you built your new system into a family car. Something as simple as a cardboard shroud and duct tape would be enough to satisfy in terms of visual observation, at least initially. (and before someone complains about that not being sturdy enough for flight, read up on fabric skin aircraft, they are not much more than this) Also, once you are in the air, act like a normal aircraft, follow the rules for altitude and airspace, keep the speeds and maneuvers in the realm of expectation, and even if you are detected you will likely blend into the background and not be noticed. At least during your atmospheric testing phase.

Once you want to start doing high altitude testing and actually reach orbit all bets are off. That area is well monitored and it is pretty much certain that someone will notice you. Your potential saving grace here is that they don't know to expect you, and can't anticipate what you performance envelope might be. There is a decent chance you can zip through the detection range faster than they can get anything set up to look at you, and evade near the ground by doing things they don't expect an aircraft to be capable of. At least for the first trip or two. Once they know to be watching, it will be much more difficult to slip away.

One other thing that comes to mind if you really want to avoid notice is to not use a family car as your platform, however easy and tempting it might be. How does your drive system work under water? If you were to build a pod that could handle submersion as well as vacuum, then you could have a lot more flexibility for disappearing after a flight, or launching from an unexpected area.

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    $\begingroup$ Key words to search for: "transponder-based radar" is called secondary radar, as opposed to primary radar. Secondary radar has major advantages in that it can more easily filter out noise returns (trees are generally not equipped with transponders) and has greater precision particularly in terms of altitude (because the transponder return can encode things like aircraft identity and current pressure altitude), but primary radar has the advantage that it doesn't require the target to cooperate; only that the target isn't actively hiding from radar. Both are available, and have their uses. $\endgroup$
    – user
    Commented Nov 29, 2018 at 8:57
  • $\begingroup$ "However, I suspect that one could dive into the dark web and find an organization dedicated to tracking satellites". I don't think you need to head onto the dark web for that. See ucsusa.org/nuclear-weapons/space-weapons/…. (The link says "nuclear weapons", but the page claims to contain all 1886 satellites currently in orbit.) $\endgroup$ Commented Nov 29, 2018 at 12:04
  • $\begingroup$ Primary radar is still very much used to detect targets without transponders. They need to track light aircraft because they can be used for drug smuggling; anything flying over national borders without transponder or ATC is likely to find the police waiting when they land. $\endgroup$ Commented Dec 1, 2018 at 12:29

Prior art: Wonder Woman's Invisible Jet

invisible jet


The flying car shall be transparent to radiation, including visible light and radar. This means that at altitude, sunscreen will be a necessity especially if you also dress like Wonder Woman. Sky colored clothes would be a nice alternative, protecting against sunburn and offering some camouflage to Mary "WW" Sue as she flies about, unconcealed by her invisible car.

Other methods of detection could be a the presence of a contrail (avoidable), or audible giveaways. This latter will be a problem since the flying car has the engine of a 1978 Fury, which you can hear from some distance. Also the horn is one of those old "AAAOOOGAH" types and she honks it a lot while flying.

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    $\begingroup$ Mach 3, in a propeller aircraft? Good luck. :) $\endgroup$
    – user
    Commented Nov 28, 2018 at 18:55
  • $\begingroup$ @aCVn old wonder woman could fly at half the speed of light, it's not the propeller that's powering the plane $\endgroup$ Commented Dec 2, 2018 at 3:54

Fortunate side-effect of Mary Sue's stealth project: anti-gravity

As it turns out: Mary Sue is not a full-time Mary Sue, she actually has a few naughty tricks up her sleeve.

What she was actually trying to do was to beat the speed radar. Attempting to mimic the principle of the superconductor and the Meissner effect of having of the magnetic field lines move around the object in question...

enter image description here

A superconducting object makes magnetic field lines go around it

...she tried to do something similar for parts of the electromagnetic spectrum, among which we find radar.

She tried to make radar waves go around the car and simply ignore it.

When she first tried her device in the family car, using the neighbourhood "You are speeding" sign as a test rig, she found two things:

  1. Yay, it works!

  2. Holy sh... I have no control over the car! It is like driving on black ice!!

Luckily she had enough presence of mind to turn off the device; the car came thumping down to the ground (since the shock-absorbers will send the car floating when the weight on them goes to zero) and she stopped before there were any dents to explain to mum & dad. Her mind went into over-drive: what the heck just happened?!

And then she realised: this device does not only bend radar around the car... it bends gravity fields around it too!

So there you have it: the government will not pick up on this thing because its primary effect was always intended to be stealth, while the anti-gravity effect was just pure luck.


  • You as the author can dial this effect back and forth however you want, to include visible light as well, fully or in part (she will want to be able to see where she is going after all) to adapt how detectable you want Mary Sue and her flying car to be.

  • It lends some credibility and eases willing suspension of disbelief to refer to superconductors since they are already are doing some really fancy levitation tricks in real life.


The best place I can think to test fly it would be inside a mountain range, as it would help you avoid a lot of detection. Radar dishes are set high up on towers to avoid picking up every tree or building in the area. "Flying under the radar" meaning you are literally flying in that gap between the tree tops and the bottom of the radar's sweep. Radar in proximity of a mountain range would have a blind spot in the range itself, so long as you're below the peaks (one of which likely has another radar dish on it). Depending on the area, the mountains could block visible observation from casual observers as well. You'd be limited in where you could fly (can't make it to space, but could test airplane or helicopter mode) but it would be relatively concealed. I'd think the mountains may help muffle sonic booms from the general population too, which would let you go a little faster. That said, be aware that such a boom might trigger avalanches if there's a lot of snow on the mountains.


I'd tell her to forget about the car. I know it would be fun to fly around in her car and that she doesn't want to wait but testing something more than 10 feet or so off the ground with a person inside is just plain dangerous.

In the short term (to keep from waiting too long), I'd suggest she lease a small cargo plane and attach the engine to the aircraft frame in the cargo hold. Once aloft using aircraft power, turn on the antigrav engine and throttle back the airplane's engines. She has a stable platform if something goes wrong - just shut down the anti-grav unit, throttle up the airplane engines and keep flying.

She can test various speeds to counteract the lift of the wings - slow it down below stall speed to show the engine is doing the 'lifting' then speed it back up.

There shouldn't be any unusual interest in an airplane flying around.

The drawback is keeping the pilot quiet.

Longer term she could buy a cargo plane.

Full testing could take months and having her own plane would lessen any growing pains as she matures her product and its reliability.

While that was going on she could start her own space agency and then get actual clearance for space flights. It might also be a good idea to check out other countries' policies for launching spacecraft if the US is too heavily regulated. She could move to one of these other countries in her anti-grav cargo plane.


what kinds of altitudes can she levitate to without drawing the government's attention?

None. Ever since this idiot caused a lot of chaos with a flying chair, the government has been paying attention.

Even if she were flying at 6 ft from the ground, a number of satellites - from government and from corporations - will pick it up. She may appear as a weird feature at Google Maps a few days later. If she's carrying a smartphone with location turned on, and she's got mobile network signal, they'll be able to double check online.

How fast can she set the throttle?

That depends on her constitution, but she should be able to withstand 2g's. 8g's and higher requires training.

How many test flights should she consider safe (either from detection or to consider the engine a success)?

Your setup is just a more sophisticated Lawnchair Larry. She's likely to win a Darwin Award at any trial.

Is there any particular places she might go to make it easier or harder to avoid detection?


What about when she's ready to call it all good and make the leap to orbit?

In a modified family car? She'll be dead before she exits the atmosphere.

Is there any way to do this covertly from Anytown, USA?

Yes. Test the thing inside a warehouse and don't use anything connected to the Internet.

  • $\begingroup$ No. No. No. And a yes (meaning no). +1 $\endgroup$
    – Mazura
    Commented Nov 28, 2018 at 22:04

There is of course the option of hiding in plain sight; register a small, low powered, home built flying machine.

Surely a craft such as this could be registered as a microlight? Here are the regs. Even if it technically wasn't inside of these regulations once it was equipped with whatever propulsion system it has that will push it into space, it could initially be operated as such an aircraft.

I do wonder what (if any) regulations and registrations the Red Bull Stratos space dive had to comply with.

Of course being a member of a gliding / paragliding / microlight club could potentially be stretched to cover initial low speed low altitude flights but the minute you start setting off sonic booms, some questions may be asked. My point though is that there are legitimate government channels available to register at least the first prototype and perform some initial test flights whereby if anyone asks who you are and what you are doing, you can show them official membership and licencing for your activity.


A car-sized object in flight will show up on radar and will be discovered. Very quickly if anywhere near a flight path or popolated area.

A friend of mine does paragliding. There are areas that are designated for those small blips in arerospace 5.000 m above sealevel on a particular starting spot for example. Just a few 500 meters higher and there is a no-flight zone for them - landing path of the local airport.

Also it's realy not adviced to fly above the city - paragliders can expect that they will be picked up by the police if they land in a park.

If you realy need to try that flying car out take it into some steep valeys where there are not a lot of people. Keep within the valley and chances are good that you'll be blocked by the mountains from radar. Don't get involved with the odd hillbilly that thinks he saw a flying car last night after quite some moonshine.


How high

Keep at or just below the tree line, building line, mountain line. Most radars cannot see through noisy environments.

Alternately take your car for a hover spin over a desert/ocean (a nice and quiet one not a busy one like near the Grand Canyon).

How does she not let everyone else know

Probably too late. Unobtanium is probably highly controlled/monitored by the government, militaries, and tech companies.

On the other hand Worthlessium is probably a by product and largely ignored. Take as much as you want.

How does she stop them from taking her invention

If she made a flying car, get a few friends with various life experiences and get them to bring their bus, cars, sheds, etc. Build a full deep-space station. And a number of autonomous drones.

Remember to kit it out with food, gardens, life-support, a radio, drilling equipment, smelters and forges, 3-d printers, a few vats of medicinal ecoli, solar panels, lots of water, and a book.

Leave early, drive out over international waters far from everyone. Pull a ninety degree up turn and leave earth. Head to high orbit.

Now make life irritating till all the governments of the world sign over exclusive rights.

To make life irritating attach drones to every satellite in orbit (there are a few). If the government launches a rocket (without permission) fly a satellite into it.

While life is becoming miserable on earth, don't stay around in orbit. Head over to the asteroid belt. Start mining, expand your space station, and get some of that lovely Unobtanium.


Either you get exclusive rights, and can sell your engines. Or you establish your own space monopoly and force the rest of Earth to accept that they have to pay you. You certainly have the engines to get around at speed up there.

  • Line the entire ship with material that acts as a Faraday cage so nothing can communicate with internal computers

  • The outside of the ship should be comprised of visual screen that compute and project the surrounding area for visual camouflage

  • hmmm I am thinking of some type of jammer or ersatz EM absorber to fool radar.

  • $\begingroup$ "compute and project the surrounding area for visual camouflage" From which angle? That works tolerably for a single observer observing from a known angle, but the moment you have multiple observers observing from different angles, the "visual screen" will need to display different images to each one of them. That would be a pretty big handwave right there, and I get the feeling (and we try to avoid answers requiring) that OP wants to avoid handwaving as much as possible. $\endgroup$
    – user
    Commented Nov 29, 2018 at 8:16
  • 1
    $\begingroup$ your suggestion to how to keep the government from detecting the car before she invents her cloaking device is to build a cloaking device? $\endgroup$
    – Mr.Mindor
    Commented Nov 29, 2018 at 20:58

Getting to orbit even with free lift has the whole issue of pressure and breathing. Making a car airtight would be a challenge. Modern passenger jets are only partially airtight -- they maintain an atmospheric density equal to about 8000 feet inside (which is why a drink affects you so strongly in flight) And at 36,000 feet you still have a quarter of an atmosphere outside. Meanwhile, they are pulling air from outside compressing it and pushing it into the cabin faster than it leaks out.

It's not clear that Mary's magical device is strictly an anti-gravity device, or if it provides thrust. If it is strictly an anti gravity device then Mary floats straight up, but drifting to the west. (Why? Because as she gains elevation, she is "on" a larger sphere than the earth. This larger sphere would require a larger velocity to keep up with the same location on the surface. First approximation, her drift speed will be .25 km/hour/km altitude gain * cos(latitude)

Take it up to 160 km up, her westward speed is now 25 kph. I don't know if this will attract attention or not. Lots of radar is set up to ignore obviously ridiculous returns to keep their operators from chasing ghosts. Being at orbital elevations but not moving at orbital speeds may be one of these.

Monetizing Mary's Magic

This assumes it's only anti-gravity.

  • Sell it to Elon Musk. Because it only goes up, and doesn't achieve orbital velocity, you still need rockets. But you aren't spending energy to get to altitude, nor punching through a thick atmosphere. If you had a 'Carrier' that took it up to say, 200 miles, and launched from there, the rocket is spending all of it's energy to achieve orbital velocity. Probably can make the rocket signficantly lighter, since it doesn't have withstand it's own weight at liftoff. Stage one becomes a lifting platform. stage two is a shuttle like space plane that gets it up to speed, but doesn't give it a circular orbit (you want the plane to recover itself in atmosphere.) Stage 3 puts it in final orbit.

  • Market it as a fuel saving device for cargo air craft. In flight, the plane travels at a lowest drag configuration, instead of at an attitude to generate sufficient lift. In addition, such a plane would no longer have weight restrictions, and could carry a much lighter fuel load. (No big fuel penalty to get up to altitude, no real need to carry a reserve. You don't have to land when you run out of fuel. Turn the engines off and wait for the fog to clear.)

  • Flying car. You have a vehicle that can take to the air. Move it forward with a prop, either on the front or back. Electric or gasoline engine. Not sure how it would handle in wind. Buildings with landing apron patios on each floor. Even if you kept them near ground level on existing road right of ways you would in effect be driving on black ice all the time. I think such a vehicle will need airfoils for control, as well as directional fans.

  • Sail plane flight times would be limited only by the occupant's bladder.

If Mary's gadget allows some degree of differential control -- e.g. just repelling the part of the earth that is behind her, then it can provide some thrust as well. In this case thrust comes at the expense of lift. But it opens up other possibilities.

  • Aircraft no longer need engines.
  • If it runs at a 1 tootsie roll to orbit economy, then floating buildings are practical. Need anchors to keep from drifting over to your neighbour's place. Don't like your neighbours? Move to that new subdivision... Urban sprawl takes on a whole new dimension.
  • Engineering pedestrian/bicycle bridges between buildings becomes trivial.
  • The personal flying harness allows people to fly like superman. But collisions would be gruesome.

Use the advantage of the machine being a car. Mary Sue should make a brief trip enough to enjoy herself and then land near a route in a discreet place. Of course she would take all reasonable measures to avoid being detected, but if spotted and questioned about a flying object, she would only have to show her driver's license and ask please to go on because she has a flight to catch. I think detected but not identified should achieve her goal anyways. Of course just in case the inside of the car should look like a car. It shouldn't be a problem with a invention like that.


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