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[Putnam]

There's probably a good place on Eve and that jetcar looks pretty small...

[miauw62]

Why is everyone talking like building a plane that can fly without wings is an achievement?

I haven't been able to build a plane that can fly with wings ;-; (they always get torn off)

[Putnam]

Anything can fly if you give it powerful enough engines. This is true in reality as well.

[tahujdt]

[BFEL]

Anything can fly if you give it powerful enough engines. This is true in reality as well.

Well...not ANYTHING.

Things like black holes can't really "fly" due to the fact if they contact atmosphere they instantly destroy whatever planet they would be "flying" around. Though I guess one method of achieving flight is to remove the ground from the equation... O.o

[Putnam]

A black hole in the atmosphere certainly wouldn't be instant! It'd be quick, of course, but not instant.

Flying isn't throwing yourself at the ground and missing; that's what orbit is!

[Graknorke]

If the black hole were small enough to fit in the atmosphere it would just dissipate I'm reasonably sure.

[puke]

black holes are not antimatter.  contacting matter does not cause annihilation, it just feeds them.

If you had a sufficiently advanced spaceship using microscopic black holes as a power source (the smaller and shorter lived they are, the more energy they give off through hawking radiation) you could refuel it (extend its life) by throwing it through the center of a planet and picking it up on the other side.

Most planets would not notice the difference.  The radiation effects as it passed through the atmosphere would be vastly more noticeable than whatever matter it absorbed on its way through the crust / mantle / core / other side.

[Sheb]

But wouldn't it be quite the problem that whatever mass you'd take from the planet, you'd have to carry around afterward? What's the energy density of black holes compared to other fuels?

[Silfurdreki]

Interesting question. So interesting I decided to check it out.

The wikipedia article for Hawking radiation gives several formulae and examples. One of the examples is semi-useful here. A ~200 ton black hole evaporates in about a second, producing a total of ~10²² J of energy. As with all large energies, for some reason, wikipedia compares with bombs; this is equivalent to 5 million megatons of TNT. Another useful comparison is that 20²² J over 1 second (i.e. Watts.) is about a ten-thousandth of the luminosity of the Sun. The volume for such a black hole, using Schwatzchild radius for volume calculation purposes, is ~10^-22 meters, i.e. significantly smaller than a proton. The energy would be released almost exclusively as high-energy gamma-rays, though so you'd probably have a tough time harnessing it. On the other hand, if you're already making tiny black holes then you should have learned to capture and harness high-energy gamma rays by now, I'd say.

So, in conclusion, <<stellar mass black holes have incredible energy densities. They don't scale well upwards, though, an earth-mass black hole has a luminosity on the order of 10^-18 W, which is not very exciting at all.

[LoSboccacc]

in other news, I made my first successful career flight with interstellar relay powered thermal turbojet!

http://imgur.com/a/Gky3n

because first gen fission reactor are soo underpowered, I had to use two massive relays - four reactors, one generator, massive radiator all over the place

I learned interesting things however:

one antenna front and one back is enough to cover 360 degree of flight, even if efficiency drop at an angle (and thrust with it)

I packed some fuel but the turbojet defaulted to consume my monopropellant first

There is massive lag when interstellar recalculate the relay path, might be an artifact of me entering and exiting the 2km physical bubble around relays.

antenna produce heat waste and thus most of the fuselage were inline radiators.

to reach space, need more booster.


edit: it was actually an ATTILA engine, shame on me

[BigD145]

It's best to put your reactors well away from Kerbal Command so you don't get physics loading during launch and such. I drive mine at least 3-4 km away. You'll have faster load time when first launching a vehicle from VAB/SPH if Command is clear of other vehicles.

[LoSboccacc]

all reactors have broken the wheels upon descending the landing strip XD

will put some in orbit before properly launching real microwave powered craft

[BigD145]

More wheels. Bigger wheels. You can also repair wheels with a kerbal. I put a reactor on a blimp and sent it over to the abandoned landing strip. You could also paradrop some around kerbin for funsies.

[stabbymcstabstab]

OK children remember this, do not make the kerbal jet pack, just don't it can save your life from a 10,000 meter free fall after being propelled by a rocket, DO NOT MOCK IT!