Ballistic Reentry vs Aerodynamic Reentry 

Col. John Stapp proved it's not how much deceleration you encounter, but how long it lasts. A few seconds at 12g might be bad, but a lot better than sustained 4g.

so long as it doesn't snap your neck. hitting concrete after falling off a ladder will give you a few milliseconds of 50g.

0.0000001 seconds of 200gs is probably worse than an hour of 4 gs

Squad is refusing to implement RealChute for years, it's so annoying.

Pluto : nope, it is not. 200g for 0.0000001 is 2*10^-12m so it is not possible to notice

I have some one on my friends list with around 24k+ hours on gmod. That is almost 3 years or 1095 days

Phone he could of had it open for most of the time he wasn't playing ... which iiiss kinda cheating about the time

@@Tagson He owns a server, and his GF also playes on the same account and they take turns moderating.

@@Tagson anyways, you could say the same for scott, as he idles out all of the space traveling.

The real question is: could we use Kerbal Space Program to solve concrete problems in AI?

Sean McDonough you can adjust to however you want mid flight in game

But it was about show how lift affect the capsule so he moved it to the runway first before opening parachute

i could be wrong but i believe Apollo 8 did as well.

September 24

@@DanSlotea holy shit really?? Well I missed it lmao

He uses the ukulele intro for his KSP videos, and the other one for his real science ones

yeah KSPs parachute simulation leaves much to be desired.... that's why RealChute is great!

not sure how, if I try the same thing my parachute rips off, I have to arm them much higher up so they open early and slow me down before opening fully.

you're not using any mods?

its been a while, so I went and tried it, and it didnt rip off, but it smashed me right into the ground for waiting that long. no mods. vanilla only.

Momentary Gs can go to 14 before death.

Likewise. I had no idea about the deliberate centre of gravity offset to generate uplift. Kewl!

I'm at a loss, how is an ax going to help?

Explain please.

@@lordgarion514 axe makes you smell better

it's a KSP video explaining the science of a rocket failure thing. best of both worlds, no?

regardless of the fact that KSP is mostly unexplained rocket failures ;)

forgetting the fact that this channel was mostly forged around ksp

This one isn't exactly as much rocket science as flight science.

A surprise, to be sure, but a welcome one.

sort of got it. What ballistic re-entry means is that the capsule is not doing any maneuvering to try and control it's decent, instead it "flies as it flies", it is un-controlled (which sounds scary hence why they say ballistic trajectory or ballistic decent), doesn't matter what altitude it is descending from. What Scott is showing us is WHY you would want a capsule to normally control it's decent (because it can reduce g-loading), he is also showing what can happen if the capsule tries to control it's decent improperly (the super fast and steep entry that resulted in really high g-loading). He then showed us how a ballistic sub-orbital reentry could be harder on the crew than a nominal re-entry from orbit (this is due to the altitude, as you said, even though returning from orbit means you start off going faster).

NEXT: DUNA lander without parachutes :)

I could understand this. After all, you guys don't use parachutes on Mars.

I did something similar thought about leaving them in orbit and sending up a rescue mission but noticed I had a stage with a 1/3 tank of propellant and a thrust greater than 1 to 1 so I decided to come in with the stage still attached and try to land with it.

I cannot seem to effectively control rockets via keyboard so all of my reentry is done with a launch vehicle that took off from a runway.

Forgetting parachutes, we’ve all been there my young grasshopper

It would be.... now I need to do research.

so this is where the heat shields video was born

It kinda makes sense. I imagine the astronauts when thinking about performing the ballistic reentry "Huh... we just had an abort due to a booster failiure... let's just keep this thing doing what it has to do, better if we don't try space cowboy with it".

"you do not need to control capsule" Well you have to spin it. Not sure if you missed that or if you're trying to simplify.

@@ewthmatth you do not... Once it sits in air flow stream its shape does it. There is no control. Again, at higher altitude you can control it, at altitude/speed they've aborted there is no such possibility. It's not a choice its posr-factum name for 'letting it fly as it flies'.

They came from orbit. MS-10 was a launch abort

Center of gravity, it's the same reason that when you throw a dart backwards it turns around in flight and sticks in the dartboard as if you threw it normally. And with bullets it's because the center of gravity is more towards the rear of the bullet that rifles have rifling, by spinning the bullet it stabilizes and doesn't tumble end over end from trying to turn itself around in flight due to the CG being towards the rear. The longer a bullet is compared to it's width the faster it must be spun to stabilize it, the first rifled guns were firing balls, they have rifling that only makes one twist in around 30 inches or so because the projectile is as wide as it is long so it only takes a small amount of spin to stabilize it, modern rifles that shoot bullets that are much longer then they are wide have a much faster twist in the rifling, usually around one twist in 12 inches. Nowadays barrel makers are making barrels with much faster twists for long range shooters, heavier bullets are best for distance shooting, making a heavier bullet to fire out of the same gun means you have to make it longer to add weight since you can't make it wider, years ago before these faster twist barrels were being made long distance shooters wouldn't even bother checking their grouping at 100 yards when testing different loads because the bullets weren't stabilized yet at that short of a distance and they would "key hole" through a paper target nailed to plywood because they would up-end and pass sideways through the target after the nose of the bullet hits the target because of the wobble they still had from not being fully stabilized yet, back then most distance shooters wouldn't even bother testing unless they had access to a shooting range of at least 300 yards. Years ago a ballistician that designed heavy artillery guns theorized that when the projectiles came out of one of those big guns they wobbled at the beginning of their 10 mile journey, everyone else in the business dismissed his theory until the 1920's and the advent of high speed film that could be slowed, turns out he was right.

do it on my channel :D

Mr.Nuclear BG this is a combination of cringe and sad

*shrug* I mean the stock game is set up the way it is to make things easy for people who don't understand these things to get their feet wet. This kind of extra realism is the realm of mods in my opinion. As long as they keep their game mod-friendly and easy to mod, and I can create my super-realistic space program sim, then I am happy

1 year late but there's a good video by AIRBOYD called Apollo - Atmospheric Entry Phase. Shots from the video appear several times in this one.

The roll rate wouldn't be enough to matter compared to the deceleration forces.

I already played it on NASA’s twitch stream. Its’s not as good as simple rockets.

Oops. Nice video though, you did a great job explaining it :)

@john smith I second that, but it has a narrow subject-liquid propellants.

I'm sorry to be that guy, but it's "descent".

I was going to make video on this.

Excellent!

I don't think skipping off the atmosphere has any danger in terms of flying off in to deep space due to the amount of velocity you need to do that. The danger lies in that their next orbit would be completely uncontrolled without any thrusters, so no fine tuning of their next landing approach or landing position. Because they had no control, their next re-entry might be too steep or too shallow again causing them to burn up or skip off again. Taking this is to account, the amount of time spent in space was longer than they had accounted for, with supplies running low, the astronauts wouldn't survive.

There is absolutely no danger of skipping off the atmosphere and going into deep space, it would be like saying that if a ball fell from a table it might rebound and hit the ceiling. What is dangerous tho is that it makes planning your landing zone quite difficult and you might end up landing on a unwelcoming surface

Upon further research this does seem correct. found a good article on it buy ESA if anyone might be interested. They even example a quote from the movie Apollo 13 and point out that it is flawed in it logic “Listen, listen, listen! They gave us too much Delta V, had us burn too long. At this rate, we’re gonna skip right off of the atmosphere, and we’re never gonna get back!”- Jack Swigert (Character) Apollo 13, the movie. Here is a quote from said article that corroborates what happened to me in KSP. Another example of KSP imitating real life. "If the entry angle is much too shallow, the spacecraft will not ‘bounce off the atmosphere like a flat stone skipping off the water surface of a pond’. A spacecraft generates little or no lift, and the outer reaches of the atmosphere are very tenuous. What will happen is that the spacecraft does enter the atmosphere at orbital velocity, but because it does not enter the denser atmosphere layers, it will not undergo much braking. It will therefore not lose enough of its velocity, and then it will simply continue on its orbit. As this orbit is slightly elliptical, the spacecraft will start gaining altitude again, go out into space and then re-enter the atmosphere after an hour (or more), as its trajectory again leads down - but then it will be at a completely different location than planned and its second entry will certainly no longer be within the ‘corridor’!" - blogs.esa.int/rocketscience/2015/02/05/the-facts-on-reentry-accurate-navigation-is-everything/

Watching Apollo 13 and other movies and even docs about the Apollo program they always seem to make it seem like if they were to miss the corridor that they would burn up or be lost in space forever. I guess that is why I was lead to believe that was the case and I didnt do my own homework. It does make sense though that unless somehow they entered too shallow and came out the other side at a speed greater than the escape Velocity of Earth that they would just continue to orbit and eventually reenter the atmosphere again but in an unpredictable way.

In Apollo 13, they needed to hit the atmosphere and land first try because otherwise the air in the capsule would of killed them before a second pass around Earth could be completed. I believe it is high CO2, not low oxygen which was what caused the air to turn bad