Oleg Zabluda's blog: December 09, 2012

Oleg Zabluda's blog

Sunday, December 09, 2012

Elon Musk on SpaceX’s Reusable Rocket Plans
Elon Musk on SpaceX’s Reusable Rocket Plans
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The key, at least for the first stage, is the difference in speed. "It really comes down to what the staging Mach number would be," Musk says, referencing the speed the rocket would be traveling at separation. "For an expendable Falcon 9 rocket, that is around Mach 10. For a reusable Falcon 9, it is around Mach 6, depending on the mission." For the reusable version, the rocket must be traveling at a slower speed at separation because the burn must end early, preserving enough propellant to let the rocket fly back and land vertically. This also makes recovery easier because entry velocities are slower.

However, the slower speed also means that the upper stage of the Falcon rocket must supply more of the velocity needed to get to orbit, and that significantly reduces how much payload the rocket can lift into orbit. "The payload penalty for full and fast reusability versus an expendable version is roughly 40 percent," Musk says. "[But] propellant cost is less than 0.4 percent of the total flight cost. Even taking into account the payload reduction for reusability, the improvement is therefore theoretically over a hundred times."

A hundred times is an incredible gain. It would drop cost for Musk’s Falcon Heavy rocket that’s currently rated at $1000 per pound to orbit—to just $10. "That, however, requires a very high flight rate, just like aircraft," Musk says. "At a low flight rate, the improvement is still probably around 50 percent. For Falcon Heavy, that would mean a price per pound to orbit of less than $500." Falcon Heavy is particularly amenable to reuse of the first stage—the two outer cores in particular, because they separate at a much lower velocity than the center one, being dropped off early in the flight.
"""
http://www.popularmechanics.com/science/space/rockets/elon-musk-on-spacexs-reusable-rocket-plans-6653023
http://www.popularmechanics.com/science/space/rockets/elon-musk-on-spacexs-reusable-rocket-plans-6653023

Labels: Oleg Zabluda

How would you defeat an 800lb gorilla in an an MMA fight?
How would you defeat an 800lb gorilla in an an MMA fight?

http://en.wikipedia.org/wiki/Mixed_martial_arts_rules#Fouls
http://en.wikipedia.org/wiki/Mixed_martial_arts#Rules

A gorilla probably can't be knocked out with punches or kicks to the head. Skull/neck is too massive and brain is too light.

A standard menu of submissions by joint manipulations, probably is not going to work either. All of them rely on the fact that your whole body (usually back) is stronger then his single limb (like say in a arm-bar). This does not hold for a gorilla. A gorilla can do biceps curls, even if you resist with your whole body. See https://plus.google.com/112065430692128821190/posts/bWRd899gmTe

His legs are proportionally weaker then his hands, so maybe knee-bar or any number of ankle locks would work, but I doubt it very much. All of those also rely on him not being able to sit up and reach you with hands. Not likely.

Nor would a rear naked choke work. That relies on him not being able to tear your arm right off. Ditto for side choke or triangle choke.

I think your best bet is to knock him out with a Thai roundhouse kick to the liver with your left leg.

But the best thing working for you is that there is no suck thing as 800lb gorilla. Even the biggest silver-back wild male gorilla is only 400lb. Morbidly obese gorillas in captivity are only 600 lb.

Alistair Overeem (280lb) knocked out Brock Lesnar (280 lb) with just suck a kick to the liver.
https://plus.google.com/112065430692128821190/posts/FUDBnMxdH4N

Little Fedor Emelianenko (240lb) submitted Hong-Man Choi (360 lb) with an arm-bar. Bob Sapp was 380 lb at one point.

http://en.wikipedia.org/wiki/Gorilla
http://en.wikipedia.org/wiki/Gorilla

Labels: Oleg Zabluda

Why all bears have such a thick neck?
Why all bears have such a thick neck? Marianna Dizik's theory - so that they can't be choked out. That's ridiculous. Who would attempt to choke a bear?

My theory - to keep his head steady enough to see whoever he is chasing after.

Идут с охоты два грузина, медведя несут, навстречу третий:
- Гризли?
- Нэт, душили.

Labels: Oleg Zabluda

Hippopotamus (Hippopotamus amphibius) "бегемот обыкновенный" is a very strange animal.
Hippopotamus (Hippopotamus amphibius) "бегемот обыкновенный" is a very strange animal. Order even-toed ungulate (отряд парнокопытные), suborder non-ruminant (подотряд свинообразных (нежвачных)). Hippo-potamus means "river horse" in Greek, but would be more correctly called "river swine" (hoiropotamus) "свинопотам". It is not kosher, either way.

Hippos are herbivorous, but why do they have such enormous and sharp canine teeth and vicious temper?

I think, since they live in the river, it is to fight alligators. A 1.5-3.0 ton hippo will bite right through a 1 ton alligator. But why hippos hang out in the river in the first place? They don't feed in the river, with only minimal consumption of aquatic plants, they only crap there, bringing the nutrients in.

Hippos leave the water at dusk (otherwise they dry up) and travel up to 5 mi inland and then spend 4-5 hours grazing on short grass, their main source of food, consuming 70kg of it each night, before coming back.

I think, it's because they they hide from lions, because hippos are just not quite big enough. Animals which don't hide from lions are White Rhinoceroses (odd-toed ungulates, 3.5-4.5 tons) and African bush elephant (4.5-6.0 tons).

Hippos seem to be right on the boundary of what a pride of lions can take, and so are giraffes (a kosher even-toed ungulate ruminant) with males weighting 1.6 tons and having a vicious kick.

Hippos reach sexual maturity not by age, but by weight (~600kg for females)

Альфред Брем в своём труде «Жизнь животных» (1860-е годы) писал:
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Только с наступлением ночи великан вылезает из воды и, сокрушая все на своем пути, отправляется на прибрежные луга или поля туземцев, которые и опустошает немилосердно, не столько съедая, сколько вытаптывая.[...] Будучи раз чем-нибудь раздражен, бегемот долго помнит обиду и старается отплатить обидчику.
"""

http://en.wikipedia.org/wiki/Hippopotamus
http://ru.wikipedia.org/wiki/Обыкновенный_бегемот
http://en.wikipedia.org/wiki/Hippopotamus

Labels: Oleg Zabluda

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