Spaceflight Manual?

[Orbin]

Some time ago someone posted a link here on the board. It was from an FAA-document(?) about re-entry.
 That's the link: https://www.faa.gov/other_visit/aviation_industry/designees_delegations/designee_types/ame/media/Section III.4.1.7 Returning from Space.pdf
I managed to find some other sections of this document via google. (namely section III, chapter 4.1.1. and chapters 4.1.3 to 4.1.6)

I really enjoy reading it. It's understandable, still not to simple. It offers formulas to use, but you don't have to have studied physics to understand it. I want more!

Does anyone know the name of the whole document and where I can find it (preferrably pdf-download)?
Has anyone read it? What are the other sections/chapters about and are they even worth reading them?

Any help will be greatly aprreciated.

[Harry Rhodan]

Those seem to be extracts from "Understanding Space - An Introduction to Astronautics" by Jerry Sellers et al.

[Plusck]

I read the extract, which was interesting enough, but I am confused.

Why does the author keep saying that at too shallow an angle you will "literally skip" off the atmosphere? That "literally skipping" expression is used several times. And when aerobraking you dive into the atmosphere and "bounce" out.

As far as I'm aware, that is just totally and utterly wrong, wrong and wrong again. 

On re-entry, you enter a circular atmosphere on an elliptical path. If you don't slow down enough you come out the other side, but there is no way you can call this "literally" skipping off the atmosphere, because "skipping" requires a force pushing you outwards, which could only be lift, and the author goes to significant lengths to show that lift is mostly irrelevant.

Likewise with aerobraking: sure you can use lift to alter your passage through the atmosphere, which is good for controlling your heating rate, minimum altitude, time spent decelerating and final orbit, but it is absolutely not necessary to have a lifting body and you definitely do not "bounce" out of the atmosphere.

So, am I missing something, or is this "skipping" notion just wrong?
I can understand it being used as a shorthand way of saying "pass through the atmosphere with insufficient deceleration", and have no problem with that (as in, "we need to make a burn to reduce Pe otherwise we'll skip instead of capturing"), but not if you keep adding "literally", and not if you imply that you need a lifting body to aerobrake.

[Steel]

Yeah the "literally skipping" part is wrong. What people tend to mean in this case is that if you're too shallow you'll not decelerate nearly enough and so it may take several passes to slow down to a sub-orbital velocity.

If you look at it from a purely height-from-the-ground point of view though, this does look like you are skipping as you'll reach a minimum altitude and then climb up again.

[kerbiloid]

When a capsule enters the atmosphere with its bottom foremost, with zero lifting force - it's a ballistic descent. It can't bounce, it just decelerates by drag force.

When this capsule enters the atmosphere with a shallow angle, the lift force appears and can change its vertical velocity sign to positive, and it will start raising as gliders do.
So, it technically can ascent over the atmosphere, and if its speed is still high, return back to an elliptic or hyperbolic trajectory. Say, making several more turns on the Earth-Moon orbit, until sticking in the air finally.

Silbervogel project intended to make a series of suborbital bounces per flight.

[Orbin]

Cool, thank you a lot...

[wumpus]

1 hour ago, kerbiloid said:

When a capsule enters the atmosphere with its bottom foremost, with zero lifting force - it's a ballistic descent. It can't bounce, it just decelerates by drag force.

When this capsule enters the atmosphere with a shallow angle, the lift force appears and can change its vertical velocity sign to positive, and it will start raising as gliders do.
So, it technically can ascent over the atmosphere, and if its speed is still high, return back to an elliptic or hyperbolic trajectory. Say, making several more turns on the Earth-Moon orbit, until sticking in the air finally.

Silbervogel project intended to make a series of suborbital bounces per flight.

The Apollo capsule was designed to do this.  I *thought* it was used, but I'm not sure.  In practice, I'm not sure which parts the capsule should be above/below where the orbit would take it returning from the Moon.

[VaPaL]

Skipping reentry should look something like this, but as far as I know, it's needes lift to perform one.

[kerbiloid]

1 hour ago, wumpus said:

The Apollo capsule was designed to do this.  I *thought* it was used, but I'm not sure.  In practice, I'm not sure which parts the capsule should be above/below where the orbit would take it returning from the Moon.

Soyuz and TKS capsules have two modes of airbraking: managed, with a lifting force and 3-4 g, and ballistic, with simple prograde and 8-9 g.
Just their aerodynamics is not so perfect to make them jumping, and their velocity is 1.4 times less than Apollo's.

Btw, not exactly skipping, but as I had just read,
The original suborbital project of Dyno-Soar (System 464L) supposed a bouncing trajectory to increase the flight range.

Edited October 10, 2016 by kerbiloid