What-If 0030: "Interplanetary Cessna"

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Max™
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Re: What-If 0030: Interplanetary Cessna

Postby Max™ » Tue Feb 05, 2013 10:56 pm UTC

PolakoVoador wrote:Chlorine trifluoride doesn't give a fuck. What crazy and scary stuff.

Preach it, I am not sure if I should be impressed or terrified that there is stuff which sets the wet sand on fire.
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Re: What-If 0030: Interplanetary Cessna

Postby Pfhorrest » Wed Feb 06, 2013 1:16 am UTC

bmonk wrote:
dudiobugtron wrote:What I learned from this 'What-if' is that Pluto is smaller than Earth's moon. No wonder they unplaneted it.

Actually just specified a definition for planet, as well as a new class, "dwarf planet"--to better classify the multitude of such objects they expect to discover in coming years.

The only thing that bugs me about that is that "dwarf planets" apparently doesn't count as a subset of "planets", which is ridiculous.

They could have solved that logical problem and all the hand-wringing in the popular media about Pluto's "demotion" by instead subdividing the class "planet" in two: say "major planets" and "dwarf planets". Then, rather than demoting Pluto from planet status, they would have promoted all the other dwarf planets to planet status, better reflecting the reality of the situation (we learned that there were lots more Pluto-like objects, not that Pluto was somehow different than we thought); while still keeping a tidy class of only eight "major planets" so we don't have young kids and average people eventually learning all the dozens or hundreds of planets (incl. dwarf planets), we just have them learn the eight major ones, and the fact that there are dozens or hundred of other dwarf ones. Instead of "Pluto is no longer a planet, it's now a dwarf planet", which just sounds stupid, it would be "Pluto is not a major planet (and never has been since that category didn't exist until now), it was the first known dwarf planet (among many others now known and many more anticipated)".
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Re: What-If 0030: Interplanetary Cessna

Postby gmalivuk » Wed Feb 06, 2013 3:47 am UTC

Ceres was discovered first, iirc. Pluto isn't the first or the nearest or the biggest or any other superlative of dwarf planet. It's just the only one that was called a planet at one point.
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Re: What-If 0030: Interplanetary Cessna

Postby Max™ » Wed Feb 06, 2013 3:55 am UTC

Very true, Ceres was discovered in like the early 1800's.
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Re: What-If 0030: Interplanetary Cessna

Postby rmsgrey » Wed Feb 06, 2013 10:05 am UTC

The main reason Pluto got called a planet is because people were looking for a predicted planet (to explain anomalies in the orbit of Neptune) when they found an object in about the right place, with about the right sort of motion - by the time they started figuring out more details about it, they'd got used to calling it the ninth planet...

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Re: What-If 0030: Interplanetary Cessna

Postby PolakoVoador » Wed Feb 06, 2013 12:38 pm UTC

Max™ wrote:
PolakoVoador wrote:Chlorine trifluoride doesn't give a fuck. What crazy and scary stuff.

Preach it, I am not sure if I should be impressed or terrified that there is stuff which sets the wet sand on fire.


The more I read about it, the more scary it gets:

Wikipedia wrote:The compound reacts violently with water-based suppressors, and oxidizes in the absence of atmospheric oxygen, rendering atmosphere-displacement suppressors such as CO2 and halon completely ineffective. It ignites glass on contact.

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Re: What-If 0030: Interplanetary Cessna

Postby Max™ » Wed Feb 06, 2013 3:33 pm UTC

PolakoVoador wrote:
Max™ wrote:
PolakoVoador wrote:Chlorine trifluoride doesn't give a fuck. What crazy and scary stuff.

Preach it, I am not sure if I should be impressed or terrified that there is stuff which sets the wet sand on fire.


The more I read about it, the more scary it gets:

Wikipedia wrote:The compound reacts violently with water-based suppressors, and oxidizes in the absence of atmospheric oxygen, rendering atmosphere-displacement suppressors such as CO2 and halon completely ineffective. It ignites glass on contact.

...ignites glass.

I recall a comment from that site about one of those materials which had listed "Recommended extinguishing media: none", kinda says it all.
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Re: What-If 0030: Interplanetary Cessna

Postby mathmannix » Wed Feb 06, 2013 4:16 pm UTC

gmalivuk wrote:Ceres was discovered first, iirc. Pluto isn't the first or the nearest or the biggest or any other superlative of dwarf planet. It's just the only one that was called a planet at one point.


According to the internet, Ceres was discovered in 1801 (before Neptune or Pluto, and after having had the existence of something in its orbit being predicted by the later-discredited Bode's Law in 1766), and was largely considered a planet until the 1860's.
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Re: What-If 0030: Interplanetary Cessna

Postby bmonk » Thu Feb 07, 2013 10:15 pm UTC

gmalivuk wrote:Ceres was discovered first, iirc. Pluto isn't the first or the nearest or the biggest or any other superlative of dwarf planet. It's just the only one that was called a planet at one point.

Not so. Between 1801, when Ceres was discovered, and about 1840, Ceres was called a planet, along with several other asteroids as they were discovered (Vesta and Pallas among them). It was the realization that there were getting to be too many of them that led to a re-classification that demoted Ceres. Some of the others no longer even qualify as dwarf planets, but were once called planets.
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Re: What-If 0030: Interplanetary Cessna

Postby Nydoc » Fri Feb 08, 2013 6:01 am UTC

orthogon wrote:
you need to approach Mach 1 just to get off the ground

Does this take into account that Mach 1 on Mars is significantly slower than Mach 1 on Earth?

Take-off speed on Mars is close to Mars Mach 1 but not close to Earth Mach 1. From what I understand, Randall is quoting Austin Meyer, the developer of X-plane:
Austin Meyer wrote:First of all, the atmosphere is ONE PERCENT as thick on Mars as it is on earth...
INDICATED airspeed is proportional the the square root of the air density, so the INDICATED airspeed is ONE TENTH the true airspeed.
The result? If you take off with 60 knots on the airspeed indicator, your REAL speed is SIX HUNDRED KNOTS! (about Mach 1)

Take note that 600 knots is a hypothetical take-off speed and not the actual take-off speed. Austin continues:
Austin Meyer wrote:A take-off in a well-designed airplane can occurr at a "mere" 400 knots or so, indicating all of 40 knots on the airspeed indicator!

So with an indicated 40 knots you are actually travelling 460 mph during takeoff. According to NASA's mach speed calculator, travelling 460 mph at zero altitude on Mars results in a Mach speed of 0.841 (sorry I can't link this excellent calculator because I'm a new member on the forums, but you can google it). A Mach 1 take-off speed is 546 mph on Mars and 761 mph on Earth.

An interesting side note is that the knot is a unit of speed equal to one nautical mile per hour and a nautical mile is is a unit of length equal to one arcminute of latitude. Mars has a smaller radius, so a nautical mile on Mars by this definition would be 982 meters and 1 Earth knot would be 1.886 Mars knots.

Well how's that for a first post? :)

Also for anyone familiar with X-plane: Randall said that the X-plane software is not capable of simulating the environment on Venus. Exactly where does it fall short? Does anyone know if a Venus flying sim has been attempted in X-plane or other simulators? Wind at 55km altitude is Cat-5 hurricane levels, but the WC-130J Hercules was able to fly inside Hurricane Katrina and it would be fun to try flying a similar plane on Venus.

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Re: What-If 0030: Interplanetary Cessna

Postby Max™ » Fri Feb 08, 2013 7:03 am UTC

Nydoc wrote:So with an indicated 40 knots you are actually travelling 460 mph during takeoff. According to NASA's mach speed calculator, travelling 460 mph at zero altitude on Mars results in a Mach speed of 0.841 (sorry I can't link this excellent calculator because I'm a new member on the forums, but you can google it). A Mach 1 take-off speed is 546 mph on Mars and 761 mph on Earth.

There ya go, I think that's the one you meant, just edited it into your quote, though it uses Java which many have turned off or removed.
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Re: What-If 0030: Interplanetary Cessna

Postby rmsgrey » Fri Feb 08, 2013 11:01 am UTC

Nydoc wrote:Also for anyone familiar with X-plane: Randall said that the X-plane software is not capable of simulating the environment on Venus. Exactly where does it fall short? Does anyone know if a Venus flying sim has been attempted in X-plane or other simulators? Wind at 55km altitude is Cat-5 hurricane levels, but the WC-130J Hercules was able to fly inside Hurricane Katrina and it would be fun to try flying a similar plane on Venus.


He said X-Plane couldn't simulate the near-surface conditions: 60+atm of boiling acid vapours hot enough to melt lead. The high pressure might be manageable, but the temperatures and the chemistry are going to be well outside the scope of "Earth-like with a few knobs to twiddle"...

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Re: What-If 0030: Interplanetary Cessna

Postby Nydoc » Sat Feb 09, 2013 12:21 am UTC

That's the one. Thanks Max!

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Re: What-If 0030: Interplanetary Cessna

Postby ijuin » Sat Feb 09, 2013 5:17 am UTC

The other thing is that the pressure at the surface of Venus not only makes the air so much denser, but it is actually above Carbon Dioxide's critical pressure. In other words, rather than behaving like a near-ideal gas, it instead behaves as a supercritical fluid, taking on some liquid-like aspects.

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Re: What-If 0030: Interplanetary Cessna

Postby EpicanicusStrikes » Mon Feb 11, 2013 1:41 pm UTC

Yeah. I'd go down pretty quickly on Snow White, too. Oberon would have to buy me a drink first.

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Re: What-If 0030: Interplanetary Cessna

Postby mathmannix » Mon Feb 11, 2013 4:16 pm UTC

EpicanicusStrikes wrote:Yeah. I'd go down pretty quickly on Snow White, too. Oberon would have to buy me a drink first.


I see what you did there... I feel the need to also mention
Venus, Europa, Io, Callisto, and Titania.

I am not going to mention Uranus.
Last edited by mathmannix on Mon Feb 11, 2013 7:40 pm UTC, edited 2 times in total.
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Re: What-If 0030: Interplanetary Cessna

Postby EpicanicusStrikes » Mon Feb 11, 2013 4:50 pm UTC

mathmannix wrote:I am not going to mention Uranus.

That's quite all right. It can speak for itself just fine.

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Re: What-If 0030: Interplanetary Cessna

Postby mathmannix » Mon Feb 11, 2013 5:08 pm UTC

Also, Ariel as long as it was the mermaid or possibly the mecha, but not if it was the warrior angel or the spirit in the tree.

(Of course, the last is the Shakespearean character for which the moon was actually named...)
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Correction on a what if article.

Postby kristinnes » Wed Feb 13, 2013 10:53 am UTC

Hello, I am not sure where else to put this, and if I know the internet right someone must already have posted this. But I wanted to post a small correction to the "Interplanetary Cessna" what if article.

At the end the author says the following:
"The batteries would help to keep themselves warm for a little while, but eventually the craft would run out of heat and crash. The Huygens probe, which descended with batteries nearly drained (taking fascinating pictures as it fell), succumbed to the cold after only a few hours on the surface. It had enough time to send back a single photo after landing—the only one we have from the surface of a body beyond Mars."

This is untrue. The russians did quite a bit of photography on other planets back in the day.
(Could not post the url to them, will try so as a reply)

It is true that the ESA and NASA have no other pictures than the Huygens probe ones from another planet. But the russian space program did some amazing work as well :)

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Re: Correction on a what if article.

Postby Klear » Thu Feb 14, 2013 10:23 am UTC

kristinnes wrote:Hello, I am not sure where else to put this, and if I know the internet right someone must already have posted this. But I wanted to post a small correction to the "Interplanetary Cessna" what if article.

At the end the author says the following:
"The batteries would help to keep themselves warm for a little while, but eventually the craft would run out of heat and crash. The Huygens probe, which descended with batteries nearly drained (taking fascinating pictures as it fell), succumbed to the cold after only a few hours on the surface. It had enough time to send back a single photo after landing—the only one we have from the surface of a body beyond Mars."

This is untrue. The russians did quite a bit of photography on other planets back in the day.
(Could not post the url to them, will try so as a reply)

It is true that the ESA and NASA have no other pictures than the Huygens probe ones from another planet. But the russian space program did some amazing work as well :)


This has been mentioned here in the discussion - what is meant by "a body beyond Mars" is "a body farther away from Earth than Mars".

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Re: Correction on a what if article.

Postby Max™ » Thu Feb 14, 2013 12:46 pm UTC

kristinnes wrote:Hello, I am not sure where else to put this, and if I know the internet right someone must already have posted this. But I wanted to post a small correction to the "Interplanetary Cessna" what if article.

At the end the author says the following:
"The batteries would help to keep themselves warm for a little while, but eventually the craft would run out of heat and crash. The Huygens probe, which descended with batteries nearly drained (taking fascinating pictures as it fell), succumbed to the cold after only a few hours on the surface. It had enough time to send back a single photo after landing—the only one we have from the surface of a body beyond Mars."

This is untrue. The russians did quite a bit of photography on other planets back in the day.
[*Max-edit* http://www.mentallandscape.com/c_catalogvenus.htm]

It is true that the ESA and NASA have no other pictures than the Huygens probe ones from another planet. But the russian space program did some amazing work as well :)

There ya go, but I think they meant a planet further out in the solar system than Mars.
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Re: What-If 0030: Interplanetary Cessna

Postby cream wobbly » Fri Feb 15, 2013 5:28 pm UTC

Randall wrote:If dropped from four or five kilometers, it could gain enough speed to pull up into a glide—at over half the speed of sound.

I can't believe nobody pulled you up on this. The speed of sound ... on Earth or on Mars?

Earth: 340.29 m/s at sea level
Mars: 244.2 m/s at zero altitude

http://www.aerospaceweb.org/question/at ... 0249.shtml

So, was the Cessna travelling at over 170 m/s, or at over 122 m/s?

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Re: Correction on a what if article.

Postby cream wobbly » Fri Feb 15, 2013 6:14 pm UTC

kristinnes wrote:
randall wrote:It had enough time to send back a single photo after landing—the only one we have from the surface of a body beyond Mars.

This is untrue. The russians did quite a bit of photography on other planets back in the day.

I'm sure Randall knows about this. There's our moon as well, even though he skipped it in his analysis! So plainly it's an error of style, using a word for its literal sense ("farther away than") in a place where it could be mistaken for its figurative sense ("other than"). It would have been better to say "at a larger orbit than Mars".

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Re: What-If 0030: Interplanetary Cessna

Postby cream wobbly » Fri Feb 15, 2013 6:19 pm UTC

SilverSkorpious wrote:This may be idiotic. I assume the answer is the same as the Sun or Venus; but what about Mercury? :oops:

Down two, across two. It's dealt with. But our moon doesn't figure. It doesn't need to figure because we know the outcome, but as the nearest body to Earth, it's still surprising it was missed.

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Re: What-If 0030: Interplanetary Cessna

Postby gmalivuk » Fri Feb 15, 2013 10:46 pm UTC

cream wobbly wrote:
SilverSkorpious wrote:This may be idiotic. I assume the answer is the same as the Sun or Venus; but what about Mercury? :oops:
Down two, across two. It's dealt with. But our moon doesn't figure. It doesn't need to figure because we know the outcome, but as the nearest body to Earth, it's still surprising it was missed.
Down three, across one.
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Re: What-If 0030: Interplanetary Cessna

Postby orthogon » Sat Feb 16, 2013 10:20 pm UTC

cream wobbly wrote:
Randall wrote:If dropped from four or five kilometers, it could gain enough speed to pull up into a glide—at over half the speed of sound.

I can't believe nobody pulled you up on this. The speed of sound ... on Earth or on Mars?

Earth: 340.29 m/s at sea level
Mars: 244.2 m/s at zero altitude

http://www.aerospaceweb.org/question/at ... 0249.shtml

So, was the Cessna travelling at over 170 m/s, or at over 122 m/s?


Maybe not that specific part, but I did ask whether the required takeoff speed, quoted as close to Mach 1, took into account the lower speed of sound on Mars, and got this excellent and detailed reply from Nydoc saying that yes, it probably did. Of course the Mach number is a dimensionless number which relates the the speed of an object to the speed of sound in the medium through which it is moving; there is a qualitative difference between travelling above or below Mach 1, whatever speed that happens to be where you live. It would be incorrect to say that something on Mars was travelling at Mach 1 if its speed equalled the speed of sound on Earth. On the other hand, saying "half the speed of sound" when you don't mean the local speed of sound isn't strictly wrong, though it is misleading.
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alt-text

Postby mrob27 » Tue Nov 19, 2013 7:27 am UTC

PolakoVoador wrote:
Max™ wrote:
Klear wrote:I only just found out that there is alt-text for each of the little pictures of crashing planes...

Thank you! I hadn't notice them. They are hilarious!

Oddly, these alt-texts are no longer present on the page (see for yourself) but I saved them.
in the alt-text, Randall Munroe wrote:Default alt-text (seen if you have the mouse in the little space between two panels): "THIS ONE HAS NO ATMO-- WHY DO YOU KEEP-- ARGH!"
Sun: "[fwoosh]"
Jupiter: "why did you send me here"
Saturn: "i'm not sure this is better"
Uranus: "this planet is the george lucas prequel version of neptune"
Neptune: "blue is good. stick with blue."
Earth: "it's hard to fly on earth because i don't actually know how to fly this thing."
Venus: "aaaaaaaaaaaaaaaaaaa"
Mars: "do we actually have to do this? we have the simulations."
Ganymede: "crap, there's no--"
Titan: "wheeeeee! hmm, it's getting chilly."
Mercury: "another one with no atm--"
Callisto: "aaaaaaaaAAAAAAAAA"
Io: "the ugliest solar system body"
Moon: "ok do we really hav--"
Europa: "do we have to do all--"
Triton: "wait can we--"
Eris: "not ANOTHER one with--"
Pluto: "ok listen i didn't--"
Titania: "i didn't sign up for--"
Rhea: "sign up for--"
Oberon: "WILL YOU STOP--"
Haumea: "STOP THIS FOR--"
Iapetus: "not another--"
"Snow White": "AAAAAAAA--"
Charon: "charon made the cut?"
Umbriel: "i don't even know where--"
Ariel: "are we almost don--"
2002 TC302R: "this one doesn't even have a name!"
Dione: "just let me--"
Tethys: "what are you tr--"
Sedna: "are you trying to pro--"
Ceres: "you could have just done 10. you seriously could have just done 10."
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Re: What-If 0030: "Interplanetary Cessna"

Postby ubikuberalles » Fri Dec 20, 2013 5:07 pm UTC

Randall wrote:Uranus: Uranus is a strange, uniform bluish orb. There are high winds and it’s bitterly cold. It’s the friendliest of the gas giants to our Cessna, and you could probably fly for a little while. But given that it seems to be an almost completely featureless planet, why would you want to?


Why fly around the 7th planet? For bragging rights, of course. "Hey! I just flew around Uranus!" /rimshot.
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Re: What-If 0030: "Interplanetary Cessna"

Postby mathmannix » Fri Dec 20, 2013 5:46 pm UTC

heh heh rimshot around Uranus.
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Re: What-If 0030: "Interplanetary Cessna"

Postby mfb » Fri Jun 28, 2019 12:54 pm UTC

Dragonfly got selected! It will fly on Titan - the current plan is an arrival 2034.


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