Everyday Astronaut video about Apollo

[Peter B]

The EA channel on YT has just dropped a 2 hour 20 minute video going through a bunch of Apollo hoax claims.

The cool bit for me was that the last section of the video demonstrated, using the rocket equation, that the Saturn V had the capacity to make Apollo happen.

Definitely worth a watch in your spare time, I think.

[LunarOrbit 🇨🇦]

I've been waiting for the weekend to watch it. I figured it would be a good video.

[smartcooky]

The EA channel on YT has just dropped a 2 hour 20 minute video going through a bunch of Apollo hoax claims.

The cool bit for me was that the last section of the video demonstrated, using the rocket equation, that the Saturn V had the capacity to make Apollo happen.

Definitely worth a watch in your spare time, I think.

This guy Tim Dodd is amazing. He used to be a professional photographer and a part time musician. The has taught himself rocket science - particularly, how rocket engines work.
Peter B beat me to the punch posting this.

I watched it yesterday. It is really well researched (although he needs to learn the difference between "fiducial" and "fiduciary" ), and the production values are right up there with the best. He has come a long way from the funny, nerdy guy in an orange Russian flight suit.

[bknight]

Cool video, nice presentation it is too bad that the ill-informed will still question the Apollo progra.

[bknight]

After sleeping I reran the video and I have a question concerning Tim's calculations concerning the rocket equation.  In all of his calculations Tim used the Earth's gravitational constant of 9.8 m/sec^2.  I wonder if the Moon's gravitational constant should be used for the CSM/LM while entering/leaving Lunar orbit and the LM's landing/takeoff.  What's the verdict?

[JayUtah]

After sleeping I reran the video and I have a question concerning Tim's calculations concerning the rocket equation.  In all of his calculations Tim used the Earth's gravitational constant of 9.8 m/sec^2.  I wonder if the Moon's gravitational constant should be used for the CSM/LM while entering/leaving Lunar orbit and the LM's landing/takeoff.  What's the verdict?

Short answer: no, you don't change g₀ to be that for the Moon. This comes up all the time while teaching rocket science. A moment's thought reveals that specific impulse and exhaust velocity have nothing to do with the gravity of anything your rocket might be operating near. All that works in deep space too.

g₀ appears in the rocket calculations to normalize the answer for differences in physical measurement units. "Specific" anything in science wants to be as dimensionless as possible. So something labeled "specific impulse" should be considered dimensionless even though it has units in seconds. To get there, you have to do undo all the physically-based measurements such as for mass, velocity, and force. Time in seconds is the only common thing in that relationship among all the measurement systems, so the physically-measured quantities are normalized to a "specific" quantity using something that exists as the same conceptual relationship in all systems. This is arbitrarily chosen to be Earth's gravity-based acceleration. It's a relationship that's defined in all systems and incorporates units of force, mass, time, and velocity—the quantities we care about when trying to measure rocket performance in terms of propellant behavior.

It's important to understand that this is arbitrary. It doesn't have anything to do with operating a rocket near Earth or anything to do with what the Earth's gravity is doing to the rocket. If you're working in SI, you undo the normalization for your units by using g₀ in SI units. If working in EES, you undo the normalization for pounds-force, gallons, firkins, and cable-lengths by applying g₀ in EES units to get exhaust velocity (for example) in feet per second instead of meters per second.

[bknight]

After sleeping I reran the video and I have a question concerning Tim's calculations concerning the rocket equation.  In all of his calculations Tim used the Earth's gravitational constant of 9.8 m/sec^2.  I wonder if the Moon's gravitational constant should be used for the CSM/LM while entering/leaving Lunar orbit and the LM's landing/takeoff.  What's the verdict?

Short answer: no, you don't change g₀ to be that for the Moon. This comes up all the time while teaching rocket science. A moment's thought reveals that specific impulse and exhaust velocity have nothing to do with the gravity of anything your rocket might be operating near. All that works in deep space too.

g₀ appears in the rocket calculations to normalize the answer for differences in physical measurement units. "Specific" anything in science wants to be as dimensionless as possible. So something labeled "specific impulse" should be considered dimensionless even though it has units in seconds. To get there, you have to do undo all the physically-based measurements such as for mass, velocity, and force. Time in seconds is the only common thing in that relationship among all the measurement systems, so the physically-measured quantities are normalized to a "specific" quantity using something that exists as the same conceptual relationship in all systems. This is arbitrarily chosen to be Earth's gravity-based acceleration. It's a relationship that's defined in all systems and incorporates units of force, mass, time, and velocity—the quantities we care about when trying to measure rocket performance in terms of propellant behavior.

It's important to understand that this is arbitrary. It doesn't have anything to do with operating a rocket near Earth or anything to do with what the Earth's gravity is doing to the rocket. If you're working in SI, you undo the normalization for your units by using g₀ in SI units. If working in EES, you undo the normalization for pounds-force, gallons, firkins, and cable-lengths by applying g₀ in EES units to get exhaust velocity (for example) in feet per second instead of meters per second.

Short answer, ok.

[smartcooky]

Its astonishing to me that Konstantin Tsiolkovsky published his Rocket Equation in May 1897, over six years before the Wright Brothers flew, and almost 30 years before Robert Goddard launched the first liquid fueled rocket.

He must have been some engineer!

[Dalhousie]

Its astonishing to me that Konstantin Tsiolkovsky published his Rocket Equation in May 1897, over six years before the Wright Brothers flew, and almost 30 years before Robert Goddard launched the first liquid fueled rocket.

He must have been some engineer!

"Just" a humble school teacher!

[JayUtah]

Rockets had been a practical reality for some time by then. The Hale rocket was available starting in the mid-1800s as a gyrostabilized missile that could be fired from a breech-loaded canon. They weren't very accurate. Nevertheless, the notion of constraining a rapid combustion was nothing new, and the mass production of a practical (if dubiously effective) rocket had already occurred.

Tsiolkovsky gets the most credit in my estimation for being an excellent physicist. It's one thing to experiment and note results that you can then harness. It's another thing to understand, quantify, and characterize the elementary principles by which something operates. He answered the question, "What's really going on here?"