To read this post please scroll down.

 

Readers! A November fund-raising drive!

 

It is unfortunately time for another November fund-raising campaign to support my work here at Behind the Black. I really dislike doing these, but 2025 is so far turning out to be a very poor year for donations and subscriptions, the worst since 2020. I very much need your support for this webpage to survive.

 

And I think I provide real value. Fifteen years ago I said SLS was garbage and should be cancelled. Almost a decade ago I said Orion was a lie and a bad idea. As early as 1998, long before almost anyone else, I predicted in my first book, Genesis: The Story of Apollo 8, that private enterprise and freedom would conquer the solar system, not government. Very early in the COVID panic and continuing throughout I noted that every policy put forth by the government (masks, social distancing, lockdowns, jab mandates) was wrong, misguided, and did more harm than good. In planetary science, while everyone else in the media still thinks Mars has no water, I have been reporting the real results from the orbiters now for more than five years, that Mars is in fact a planet largely covered with ice.

 

I could continue with numerous other examples. If you want to know what others will discover a decade hence, read what I write here at Behind the Black. And if you read my most recent book, Conscious Choice, you will find out what is going to happen in space in the next century.

 

 

This last claim might sound like hubris on my part, but I base it on my overall track record.

 

So please consider donating or subscribing to Behind the Black, either by giving a one-time contribution or a regular subscription. I could really use the support at this time. There are five ways of doing so:

 

1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.

 

2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation. Takes about a 10% cut.
 

3. A Paypal Donation or subscription, which takes about a 15% cut:

 

4. Donate by check. I get whatever you donate. Make the check payable to Robert Zimmerman and mail it to
 
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652

 

You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above.


Blue Origin has successfully tested its new hydrogen/oxygen rocket engine.

The competition heats up: Blue Origin has successfully tested its new hydrogen/oxygen rocket engine.

This would be the second new American rocket engine since the 1980s, following SpaceX’s Merlin engine. That it uses hydrogen/oxygen is also significant, as these fuels provide the highest ratio of power to weight. (As far as I remember, the shuttle was the only other spacecraft to use hydrogen/oxygen.)

Post corrected. Thanks Paul!

Genesis cover

On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.

 

The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.


The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
 

"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News

6 comments

  • Paul Howes

    Other way round, Bob! Highest power to weight ratio

  • Chris Kirkendall

    I thought one of the engines used on Apollo was a Hydrogen/Oxygen engine (maybe not the main engines on Saturn V though) – ?? Anyone know?

  • Patrick Ritchie

    LH2/LOX offers the highest ISP of commonly used rocket fuels.

    Lots of US engines us Hydrogen, but not so many first stages.

    Off the top of my head:

    J2 – used on upper stages of Saturn V
    RS-68 – Delta IV first stage
    RL10 – Used in the Centaur upper stages, Saturn I, Atlas, Titan etc… Still used on Atlas V and Delta IV upper stages.

  • Chris Kirkendall

    Thanks for that info Patrick – I figured someone here would know! This site is such a great resource – so many knowledgeable folks here. BTW – why are Hydro/Oxy engines used only for upper stages & not for main booster engines?

  • Patrick Ritchie

    Some first stages use LOX/Hydrogen, notably the RS-68 on the Delta IV and the SSME on the space shuttle.

    As to why LOX/LH2 is best suited for upper stages: as I understand it high thrust beats out efficiency on the first stage but lower gross weight and higher efficiencies win out once you’re in vacuum.

    This favors RP1 for first stages and LH2 for upper stages.

    This isn’t a hard rule and the devil is in the details. The Russians use RP1 on almost all their stages (I believe Energia was the exception).

  • Chris Kirkendall

    … high thrust beats out efficiency on the first stage but lower gross weight and higher efficiencies win out once you’re in vacuum.

    Makes sense to me – thanks !

    Come to think of it, with the weight of all the propellant & large 1st stage at the start of the launch, a little extra engine weight would probably be more or less negligible. Once most of that is consumed & the vehicle’s outside most of Earth’s atmosphere, the remaining stage(s) & fuel would weigh much less (booster stage long gone at that point), the engine weight probably accounts for a bigger % of the total remaining vehicle weight & therefore makes a bigger impact on performance…

Leave a Reply

Your email address will not be published. Required fields are marked *