General Science and Off-Topic Questions That I Ponder

[NASI Director]

1.) I know the equation to find dV, but how would I calculate the ISP and dV of multiple engines?

2.) How can I find the volume of a sphere?

3.) How much dV does it take to orbit the real Moon?

4.) How much dV does it take to intercept and circularize around the Moon?

5.) Why is it called the Moon? Why isn't it called Luna or something?

6.) How can find the strength of a lightweight material such as aluminum (is there an equation for it)?

7.) How long does it take radio signals to get to Mars? To the Moon?

8.) Is a mile 2.2 kilometers or is it 1.2?

9.) It kilometer pronounced "Keelow meeter" or "Kehlohmehter?"

10.) Why is English even here? Didn't derive from Anglish or the Anglo-Saxon language?

11.) How slow would a safe landing be?

12.) How much dV did the Saturn V rocket have? With payload? Without?

13.) Why do I ask so many questions?

14.) Why do we accept the Uncertainty Principle as law?

15.) How do we create electricity to make our muscles move?

16.) Why do we accept the laws of Thermodynamics and Newton's Laws to be the number one law?

17.) Why doesn't America fund their space program more?

18.) Why doesn't America fund their science programs more?

19.) Why is KSP so addicting?

20.) What do the devs of KSP look like? Who are they?

21.) Why do I like instrumental versions of songs better than the actual with-lyrics version of them?

22.) Why does Germany have such a bad reputation?

23.) Mein Deutsch bin sehr schlecht?

I may remember more later on and I'll post them in the comments.

Edited September 8, 2013 by NASI Director

[pxi]

Meh I'll have a go at a few of these before bed:

2: 4/3 Pi * Radius Cubed

5: Both are valid names, moon is more popular

7: About 8 minutes or so iirc for mars (depends on the exact distance between mars and earth too), a few seconds or so for the moon

9: Po-tay-to poh-ta-to

10: Languages evolve, compare shakesperian english to modern english - bit of a difference.

11: Slow enough that you land safely. (It's subjective.)

13: you're bored?

14: Because the only thing we can be certain of, is our uncertainty.

16: Because they're very useful, and hold true for the most part.

19: Because awe is comparible to heroin.

22: There was this thing that happened in the 1940's, commonly referred to in Ireland as 'the emergency'.

Hope that helped!

Edited September 8, 2013 by pxi

[NGTOne]

1. Not sure. Wikipedia is your friend.

2. vsphere = (4/3) pi*(r^3)

3. From LEO, about 4.8 km/s.

4. See above.

5. In Latin, it is/was called "Luna". "Moon" is derived from an archaic Germanic language of about 1000 years ago.

6. You have to be more specific (Tensile? Compressive?). Ask an engineer.

7. Earth-Moon: ~1.26 seconds. Earth-Mars: Anywhere between 8 and 22 minutes (depending on time of year).

8. It's actually about 1.6 kilometers.

9. Both are correct - comes down to personal preference.

10. English is actually a funny mashup of Latin and various Germanic and Nordic languages, which evolved over time due to the many foreign invasions of the British Isles.

11. In KSP? I try for no faster than about 0.1 m/s, though I know other people come in as fast as 3 m/s.

12. The Saturn V was purpose-designed for the Moon missions. Therefore, it had enough dV to achieve lunar intercept from the ground, about 11 km/s.

13. Beats me - ask a shrink.

14. Because it accurately describes certain observations of the physical universe (the electron-slit experiment being the most notable example).

15. Not sure - ask a biologist.

16. Newton's Laws are approximations for a non-relativistic non-inertial reference frame. Thermodynamics is Law #1 because it matches everything we've ever observed - there is no net change in the amount of energy, just in the form of that energy.

17. Because politicians are stupid.

18. See "politicians are stupid", above.

19. It's addictive because it allows you to explore the great void, and learn and invent and develop on your own.

20. There's a "post pictures of yourself" thread around here somewhere, maybe the devs have posted there.

21. Personal preference. Maybe your parents liked it that way?

22. Nazis. No further explanation needed.

23. I don't speak German.

[NASI Director]

24.) How much dV does it take to get into a 70x70km orbit around the Mun? How much to land from that altitude?

[NASI Director]

25.) Why is it that in KSP, when you orbit higher, you go slower but in real life when you swing something around a pendulum the end goes faster the farther it is away from you? Is that an example of the great KSP physics I hear about?

[sojourner]

www.google.com

[NASI Director]

www.google.com

However half of the things I asked that have not been answered are not google-able.

[Awaras]

25.) Why is it that in KSP, when you orbit higher, you go slower but in real life when you swing something around a pendulum the end goes faster the farther it is away from you? Is that an example of the great KSP physics I hear about?

Because the force the string exerts on the object you are spinning around is constant no matter how long it is while the force of gravity drops at the square of the distance?

15.) How do we create electricity to make our muscles move?

Actually, the muscles are NOT powered by electricity. The nervous system produces relatively tiny amounts of electricity that would not be enough to power any significant movement. The electric current is used only to transmit a signal to the nerve ending touching a part of the muscle itself. Once that signal is received, the nerve ending releases a chemical that goes into the muscle cell where it triggers a reaction that causes the muscle to contract. This reaction is powered by 'burning' ATP - an energy rich compound that fuels most of the processes that make life possible.

Of course, this is just a gross oversimplification of the whole process...

Edited September 8, 2013 by Awaras

[K^2]

However half of the things I asked that have not been answered are not google-able.

But the other half are. Why don't you put some effort into it yourself? The other half aren't "google-able" because they are wrong questions. If you learned a little bit about how things work rather than try and memorize trivia, you'd understand why. And if you don't try to understand how these things work, just knowing these things isn't going to be of any use.

[Jackissimus]

Don't lose your nerves over him, I think he is at least half trolling. This is not how you would ask a question if you genuinely wanted to know the answer. Where are the mods anyway?

[Omicron314]

I believe the equation to calculate the ISP of multiple engines is (thrust1 + thrust2 + thrust3 + ... + thrustfinal)/(thrust1/Isp1 + thrust2/Isp2 + ... + thrustfinal/Ispfinal)

[lajoswinkler]

There was this great time when Google was not used to ask questions (because it sucks at AI), when people would type in keywords and then look for pages that contained them. I still live in that time.

[znode]

Isp is constant no matter how many engines you add. Ultimately, ISP is a measure of efficiency - it's the ratio of force versus mass ejected, and is totally proportional to the exhaust velocity. That's a property of the engines, not how many engines you have.

It's like firing bullets out of guns - no matter how many guns you have firing at the same time, it won't increase the speed of any of the bullets; it just means more bullets in the air at a time.

What this means in practice is that dV does NOT go up with more engines, because your ISP stays constant - in fact, the more engines you add, the less dV you get, because the engines weigh you down. What adding engines give you is TWR at the cost of your dV.

[NASI Director]

26.) Why can't a jet engine work with oxidizers? Can you use a rocket engine without oxidizers in an atmosphere like our own?

[Naten]

26.) Why can't a jet engine work with oxidizers? Can you use a rocket engine without oxidizers in an atmosphere like our own?

*cough*Reaction SABRE (Synergistic Air-Breathing Rocket Engine) is a concept under development by Reaction Engines Limited for a hypersonic precooled hybrid air breathing rocket engine. The engine has been designed to achieve single-stage-to-orbit capability, propelling the proposed Skylon launch vehicle. SABRE is an evolution of Alan Bond's series of liquid air cycle engine (LACE) and LACE-like designs that started in the early/mid-1980s for the HOTOL project.

The design comprises a single combined cycle rocket engine with two modes of operation. The air breathing mode combines a turbo-compressor with a lightweight air precooler positioned just behind the inlet cone. At high speeds this precooler cools the hot, ram-compressed air leading to an unusually high pressure ratio within the engine. The compressed air is subsequently fed into the rocket combustion chamber where it is ignited with stored liquid hydrogen. The high pressure ratio allows the engine to continue to provide high thrust at very high speeds and altitudes. The low temperature of the air permits light alloy construction to be employed which gives a very lightweight engineâ€â€essential for reaching orbit. In addition, unlike the LACE concept, SABRE’s precooler does not liquefy the air letting it run more efficiently.

After shutting the inlet cone off at Mach 5.14, 28.5 km altitude, the system continues as a closed cycle high performance rocket engine burning liquid oxygen and liquid hydrogen from on-board fuel tanks, potentially allowing a hybrid spaceplane concept like Skylon to reach orbital velocity after leaving the atmosphere on a steep climb.

An engine derived from the SABRE concept called Scimitar has been designed for the company’s A2 hypersonic passenger jet proposal for the European Union-funded LAPCAT study.[6]

In November 2012, Reaction Engines announced it had successfully concluded a series of tests that prove the cooling technology of the engine, one of the main obstacles towards the completion of the project. The European Space Agency (ESA) has evaluated the SABRE engine's pre-cooler heat exchanger, and accepted claims that the technologies required to proceed with the engine's development had been fully demonstrated.

As of July 2013, the United Kingdom has earmarked £60 million for the development of a full-scale prototype of the SABRE engine, citing the viability of its core technologies based on testing performed by the ESA.*cough*

source

[NASI Director]

27.) What is the difference between inertia and momentum?

28.) Who in the world still says "tomahtoe" or "pohtahtoe?"

[nhnifong]

However half of the things I asked that have not been answered are not google-able.

Typically it works better to search for answers than to search for questions. For example:

query: How can I find the volume of a sphere result: wordy response form about.com, other junk

query: "the volume of a sphere is" result: first two results actually have the formula in the excerpt. no need to even click.

query: Why does Germany have such a bad reputation result: Crap from yahoo answers, people guessing.

query: "Germany's reputation has been" result: Current or past events from european news sources that are actually informative