Bob Braeunig's Apollo Pages

[ka9q]

Bob, your plot of the ground track vs the geomagnetic equator is great. It shows as well as any 2D display can show how the trajectory was designed to avoid the heart of the VABs, though it does assume one knows that they're densest at the geomagnetic equator.

Those Youtube videos showing the 3-D path of Apollo 11 are also a great resource. They should have driven a stake through the heart of the hoaxers' radiation claims but that would be too much to ask for.

[ka9q]

Looking back at the beginning of this thread reminded me of a rather odd Russian hoax claim that the F-1 engine didn't perform as well as NASA claimed, Saturn V velocity at S-IC/S-II staging was only half that claimed by NASA, and the whole stack therefore couldn't send Apollo to the moon.

Bob, since you've already simulated a Saturn V launch perhaps you have some thoughts on debunking this particular argument. I'd like to do it by showing that the claim is incompatible with the known physical dimensions of the Saturn V (which have been physically seen by millions) and its known, observed flight properties (also witnessed by millions in person). We can nail down the dimensions of the various rocket stages, the liftoff acceleration (from the tower clear time) and the S-IC flight time.

A rocket can "underperform" in one of two ways: by providing less than rated thrust or by achieving a lower than specified Isp -- burning propellants faster for the same thrust. Because we know the S-IC's physical dimensions and flight time, we can bound the propellant flow rate and show it wasn't higher than NASA claimed.

That leaves low thrust. As everyone knows, at liftoff the Saturn V had a thrust/weight ratio barely above 1. Any loss of thrust meant that it wouldn't even get off the pad. Assume that a crafty NASA compensated for this by reducing the weight of the upper stages, perhaps by offloading their propellant tanks. The watching public at KSC would be none the wiser when the rocket fell into the eastern Atlantic or achieved earth orbit without enough propellant for TLI.

Would tricks like this be sufficient to get an underperforming S-IC off the pad yet achieve only half its rated velocity at staging? Are you interested in working this out with me?

[Bob B.]

Jul 20, 2011 17:30:08 GMT -4 ka9q said:

Offhand (check me on this) a typical Apollo parking orbit had an inclination of around 38 degrees. It varied in real time through the launch window to keep the moon in the orbital plane as the earth rotated. That means the spacecraft never passed 38N during its transfer to the moon. It attained its high geomagnetic latitude for VAB avoidance purposes by passing through those altitudes over the southeastern USA where the geomagnetic latitude is much higher than the geodetic (ordinary map) latitude.

38 degrees is a bit too much. Most of the parking orbits were inclined about 32.5 degrees, though a few were less. The following table gives the Earth orbit data:

history.nasa.gov/SP-4029/Apollo_18-21_Earth_Orbit_Data.htm

In most cases the TLI maneuver lowered the inclination a little bit, though not more than a couple degrees. The following table gives the translunar injection data:

history.nasa.gov/SP-4029/Apollo_18-24_Translunar_Injection.htm

Combining a plane change and an altitude change together into a single maneuver greatly reduces the delta-v versus performing separate maneuvers. A small plane change of a degree or two can be achieved for near negligible delta-v. In fact, when satellites are injected into geostationary transfer orbits, the inclination is typically reduced a couple degrees because it's almost free to do so. The rest of the plane change is performed when the orbit is circularized at apogee of the transfer orbit. Since the satellite is moving more slowly at geostationary distance, it doesn't take as much delta-v to make the plane change.

I talk about this in my web page along with some sample problems:

www.braeunig.us/space/orbmech.htm#maneuver

If anyone analyzes this today keep in mind that the earth's magnetic poles are moving very rapidly; they're no longer where they were in 1969.

My chart in Reply #42 is based on the 1969 location.

[Bob B.]

Jul 20, 2011 17:45:22 GMT -4 ka9q said:

Looking back at the beginning of this thread reminded me of a rather odd Russian hoax claim that the F-1 engine didn't perform as well as NASA claimed, Saturn V velocity at S-IC/S-II staging was only half that claimed by NASA, and the whole stack therefore couldn't send Apollo to the moon.

We had a thread about this last year:

apollohoax.proboards.com/index.cgi?action=display&board=theories&thread=2732

If you want to revisit this, I'll join in the discussion. Maybe we can bump the old Pokrovsky thread and and continue the discussion there.

By the way, I recently saw somewhere that Pokrovsky's paper has been translated into English, but I can't find it now.


(edit) I found the english version:

www.aulis.com/saturn_v.htm

Naturally it's hosted by aulis.com (David Percy).

[gwiz]

Someone raised the topic over on UM recently, and they did a pretty good job of showing where Podrovsky went wrong. It starts here.

[lukepemberton]

Jul 20, 2011 18:31:29 GMT -4 Bob B. said:

Naturally it's hosted by aulis.com (David Percy).

The very mention of that name makes my blood boil.