Don't try this anywhere

[caecilliusinhorto]

This is an actual meme that Pythom themselves posted to their blog

[RCgothic]

5 hours ago, mikegarrison said:

Nothing ever gets *fully* combusted.

*Especially* when your rocket engine is chugging!

[DDE]

2 hours ago, caecilliusinhorto said:

This is an actual meme that Pythom themselves posted to their blog

That they need to remind people of what their logo is, but RocketLab is supposed to be instantly recognizable...

[steve9728]

There have a meme in China: Anyone with a dream is amazing, and with courage comes miracles. Well you know, that can become a meme is not because the literal meaning 

And if it were me I won't put those bottles like that. At least I won't do that when I doing a Zoom meeting about the rocket safe.

[jimmymcgoochie]

Furfuryl alcohol and nitric acid?

Congratulations! You've invented the Aerobee a whole seven decades late!

(OK, the Aerobee also used aniline too, but close enough).

Which promptly reminded me of this:

 

[kerbiloid]

4 hours ago, jimmymcgoochie said:

Furfuryl alcohol and nitric acid?

Let's just hope that they won't confuse the hoses on siphoning the fuel by mouth.

(Who came up with calling various inedible substances "alcohol"?
How can it be an alcohol when one can't drink it?
Nonsense.)

P.S. Is pythom's crush called "amaconda"?

[sevenperforce]

1 hour ago, kerbiloid said:

P.S. Is pythom's crush called "amaconda"?

No, I think the crush of a pythom is called constrictiom. 

7 hours ago, steve9728 said:

And if it were me I won't put those bottles like that. At least I won't do that when I doing a Zoom meeting about the rocket safe.

I don’t see why they are bothering with nitric acid and alcohol when all they really need is a bottle of vinegar and some baking soda. 

[DDE]

6 hours ago, jimmymcgoochie said:

Furfuryl alcohol and nitric acid?

Congratulations! You've invented the Aerobee a whole seven decades late!

Well, they do say everything necessary to go to Mars has already been invented...

[linuxgurugamer]

28 minutes ago, DDE said:

Well, they do say everything necessary to go to Mars has already been invented...

But not yet perfected

[jimmymcgoochie]

3 hours ago, kerbiloid said:

Let's just hope that they won't confuse the hoses on siphoning the fuel by mouth.

Anyone who puts a tube that may or may not contain concentrated nitric acid near their mouth should not be allowed anywhere near combustible materials.

Not sure why they're using furfuryl alcohol and nitric acid though, when alternatives such as Coke and Mentos or barbecue gas and compressed air exist and are much safer to handle. Coke and Mentos is quite clearly hypergolic, since they react on contact, and they're both made largely of plant-based materials so they've got the green credentials to go with it. Win-win!

[sevenperforce]

1 hour ago, jimmymcgoochie said:

Coke and Mentos or barbecue gas and compressed air exist and are much safer to handle. Coke and Mentos is quite clearly hypergolic, since they react on contact, and they're both made largely of plant-based materials so they've got the green credentials to go with it.

Technically, Diet Coke is a monopropellant; Mentos are the (consumable) decomposition catalyst.

Although even more technically/pedantically, it’s not chemical decomposition but rather runaway physical precipitation of a dissolved gaseous solute in a liquid solvent. The presence of aspartame in Diet Coke (in lieu of sucrose in regular cola) decreases the viscosity of the solvent, allowing higher exhaust velocities; there is also some speculation that aspartame tends to help stabilize bubble formation.

I believe the maximum theoretical specific impulse of a Diet Coke+Mentos combo is somewhere in the neighborhood of 20 seconds. All the Pythom team needs to do is convert all the water in Earth’s oceans into Diet Coke and they’ll be at least 0.03% of the way to reach the amount of propellant they’ll need to reach orbit. 

[Kerbart]

On 4/11/2022 at 2:50 PM, darthgently said:

Pythom, not python.  I googled thinking a pythom must be some obscure bird.  No result

After watching the video I would not automatically dismiss the hypothesis that they misspelled the name. And not because they try to avoid trademark issues.

[StrandedonEarth]

2 hours ago, sevenperforce said:

I believe the maximum theoretical specific impulse of a Diet Coke+Mentos combo is somewhere in the neighborhood of 20 seconds

[sevenperforce]

16 minutes ago, StrandedonEarth said:

Extracting the maximum specific impulse from a Mentos+Diet Cola combo would require a long, narrow precipitation chamber which would allow the fluids to exit but redirect the gases back upwards in order to maintain pressure.

Two liters of diet cola contain approximately 12 grams of dissolved carbon dioxide. I’m going to go out on a limb and make the entirely unscientific estimate (based on my prodigious bartending capabilities) that the empty space in an average 2-liter bottle is about 6 fluid ounces or 177 mL. The molecular weight of air at standard mix is 28.97 g/mol while the molecular weight of carbon dioxide is 44.01 g/mol, so using the ideal gas equation carbon dioxide will occupy 65.83% as much volume as an equivalent mass of standard-mix air.

The density of air at STP is 1.225 kg/m^3 or 0.00122 grams per mL. That 177 mL can hold approximately 0.216 grams of air at STP (although we assume it already contains air at STP). A little math and we learn that precipitating all the carbon dioxide from two liters of diet soda would raise the pressure in that 177 mL from 1 atm to 38.6 atm.

Now, in order to expand that 177 mL of gas from 38.6 atm to 1 atm, you’d need 6.83 Liters. But we only have 2 Liters to work with. So the work done by the gas in expanding, using the pressure-volume law, comes to 489.4 Joules.

Soda has a density equivalent to water, so two liters of the stuff weighs 2 kilograms. KE=mv^2/2, so the exhaust velocity is 22.2 m/s or a miserable 2.26 seconds.

Mars, here we come!

I will note FWIW that the maximum achievable height for a perfectly optimized mentos+coke geyser is, by basic math, 25.1 meters. 

[kerbiloid]

There are standard parking places on the Cola video.

Idk, how wide they are, but if somebody can measure them on the parking, we could know exact distance passed by the (2 kg?)  bottle.

I have watched the video at 0.125^x speed in VLC, and even the line crossing moments are detectable, so we could even build L(t) diagram.

All of that gives us the bottle acceleration, and (*  mass) the thrust force.

As we can measure the bottle throat diameter, we can divide the force by the throat cross-section area, add the atmospheric pressure, and get the actual gas pressure value inside the bottle.

Edited April 25, 2022 by kerbiloid

[Deddly]

Maybe we can take the highly interesting and amusing, yet off-topic discussion of coke and Mentos to a separate thread, please? 

[Deddly]

Regarding the name "Pythom", I understand that the owners are Swedish. Their names are Tom and Tina Sjögren. In Swedish, the "thom" part of the name would be pronounced the same as "Tom". Could that be what they're doing? As for the first part, "pyra" means to smoulder in Swedish. Perhaps the whole thing is a play on words.

They both seem to be quite accomplished individuals. Tina is in the  Guinness Book of World Records for being the first woman to ski unsupported to the North Pole, and she holds another record for being the first woman to complete the "three poles challenge" (reaching the North Pole, the South Pole and the summit of Mount Everest. Tina and Tom also jointly hold the record for being the quickest to reach the North and South Poles one after the other unsupported.

So they seem to be explorers and/or adventure junkies. Completing those tasks requires not only physical and mental endurance but also some considerable planning and research skills. I'm not saying they're going to make it (especially in the timeframe they're going for), and it will almost certainly end up in a huge explosion, but I think it would be a mistake to write them off completely.

[sevenperforce]

7 minutes ago, Deddly said:

So they seem to be explorers and/or adventure junkies. Completing those tasks requires not only physical and mental endurance but also some considerable planning and research skills. I'm not saying they're going to make it (especially in the timeframe they're going for), and it will almost certainly end up in a huge explosion, but I think it would be a mistake to write them off completely.

Agreed, in the sense that their basic concepts are not prohibited by the laws of physics. If you want to go to Mars in a bare-bones probable-suicide mission, this is the way to do it. But physical possibility doesn’t make it feasible. 

[Deddly]

9 minutes ago, sevenperforce said:

If you want to go to Mars in a bare-bones probable-suicide mission, this is the way to do it. But physical possibility doesn’t make it feasible. 

Yes. The couple certainly don't seem to be averse to taking risks - they had been planning a winter ascent of K2 before changing their destination to Mars. Any attempt to climb K2 carries a 25% risk of death, and a winter ascent is just madness, but it has been done. So what's unfeasible in our eyes is most likely an acceptable risk in theirs, since they plan on sending themselves, not someone else.

EDIT: I think their biggest challenge will be funding it. They're going for the small sat market, and there are already a lot of players there. Even if they can undercut the prices charged by the competition, will they manage to get enough customers who are willing to risk their payloads on a bare-bones launch system? I'm not going to say it's impossible, but it's certainly going to be a challenge.

Edited April 25, 2022 by Deddly

[DDE]

5 hours ago, Deddly said:

So they seem to be explorers and/or adventure junkies. Completing those tasks requires not only physical and mental endurance but also some considerable planning and research skills. I'm not saying they're going to make it (especially in the timeframe they're going for), and it will almost certainly end up in a huge explosion, but I think it would be a mistake to write them off completely.

What worries me is that they disappeared for two decades after their initial accomplishments. Perhaps their thirst for one last flood of adrenaline may be getting the best of them.

[kerbiloid]

Spoiler

On 4/25/2022 at 2:50 PM, Deddly said:

Maybe we can take the highly interesting and amusing, yet off-topic discussion of coke and Mentos to a separate thread, please? 

To SpaceX thread, probably.

https://www-rbc-ru.translate.goog/business/28/04/2022/626a4b6b9a79475af0c7c670?from=newsfeed&_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=ru