What does "23 Hoover Dams" refer to?
By
William Vietinghoff
In August, 1972 the contract was signed that directed Rocketdyne to design and build the Space Shuttle Main Engine. In 1977 I was assigned to the Space Shuttle Main Engine Development group. We were located upstairs in Building 001 in the Engineering Annex at the campus in Canoga Park (6633 Canoga Ave), the facility where the engine was built. Byron Wood was my manager. (He eventually rose to be President). By then development engines had been built and were undergoing testing. No engines had been delivered as yet for flight. The orbiter was being subjected to Approach and Landing Tests (ALT). For those tests the Orbiter was strapped to the back of a Boeing 747, taken aloft, and released. Successful landings were demonstrated. The Rockwell Space Division designed and built the Orbiter. In late 1977 I was contacted by Joyce Lincoln, a woman on the staff of the Public Relations/Customer Relations Department of Rocketdyne. Nowadays that group is named "Communications". Joyce had Public Relations responsibilities. She met with me and asked if I could take an assignment. The company wanted to broadcast to the world what an engineering achievement the SSME represented and to emphasize the power that it could develop. Even though the engine had not flown as yet, I knew I was working on a remarkable piece of hardware.
"We want some 'Gee-Whiz' words about the shuttle engine," she said. "You know, "faster than a speeding bullet - can jump over tall buildings". She emphasized that I must explain these features in terms that the lay person could understand and be able to visualize. "For example," she pointed out, "I know the engine has a very high specific impulse and an extremely high combustion chamber pressure, but who would know what that means?"
I figured I could squeeze the task in with whatever else I was doing and took the job.
As background, I have to point out that the "rated" thrust for the SSME is 375,000 lbs at sea level and 470,000 lbs at altitude (vacuum). As you may know, the Space Shuttle Main Engine is throttleable - that is, the thrust can be varied from 65% of rated (called "Minimum Power Level") to 109% of rated (originally called "Emergency Power Level" and later re-named to "Full Power Level"). However, the engine had not yet been tested at the 109% thrust level in 1977 because of low performance and engine failures. This was a major concern. In fact, we received a visit in our area by John Young and Bob Crippen, the first astronauts to fly the Shuttle. That was one of the questions they asked us: When will the 109% (Full Power Level) be attained? It was eventually demonstrated in 1981.
The SSME uses liquid hydrogen as fuel and liquid oxygen as oxidizer, the combustion product being steam (water). For the purposes of generating the most impressive numbers for my "gee-whiz" statements I used the propellant flow rates for the combined three engines at the 109% power level. My trusty copy of Perry's Chemical Engineer's Handbook gave me the energy released (Heat of Combustion) in BTUs per lb by the burning of hydrogen and oxygen. The known propellant flow rate in lbs per second easily converts to BTUs per second or watts or any equivalent unit of energy.
Then I spent a day in the company library looking up devices or systems that either generated or used energy with which I could make numerical comparisons. I played around with the power of Boeing 747 jets, with diesel locomotives, with automotive engines. I came across Hoover Dam. Based on the power output of the dam published for that period, I calculated that the three engines developed as much power as 22.97 Hoover Dams, a figure I have not shared with many people (now you know!). I asked myself what that decimal value could possibly mean to anyone other than an engineer; so I rounded it off to 23 Hoover dams.
In brainstorming more incredible facts for Joyce, I wanted to do some comparisons with the very high propellant flow rate. One day I was standing by the desk of Dorothy Rowlands, secretary to Ed Larson, Director of Design Technology at Rocketdyne. I asked Dorothy if she had a swimming pool; I didn't. She said she did.
I asked if she knew how many gallons it held. She told me the precise figure. I asked her how she could be so certain. She told me that if she ever had to empty and re-fill it, she wanted to know in advance how much it would cost her.
Using the volume she gave me, I calculated that the three shuttle engine propellant pumps, at Full Power Level, would drain her pool in 25 seconds. That became another of my "Gee-Whiz" statements.
It turned out to be very popular. Somebody inserted that fact into the Space Shuttle Main Engine page on Wikipedia:
http://en.wikipedia.org/wiki/Space_Shuttle_main_engine
That fact was quoted by the narrator during the launch of the shuttle Discovery on February 24, 2011. Go to this YouTube coverage:
http://www.youtube.com/watch?v=xPkJ8ugK3_0
The quote is spoken about half-way through the narration.
I created about a dozen such comparisons or performance statements. I bundled them up and turned them in to Joyce. She sent them to the Program Manager, Dominic (Dom) Sanchini, and to the Rocketdyne President, Norman Ryker. They both approved the package. Joyce sent me a signed copy for my files.
Joyce prepared Press Kits with my "Gee-Whiz" statements. They published them as "Space Shuttle Engine Incredible Facts" or "Amazing Facts". She must have sent the kits to hundreds of newspapers, magazines, radio and television stations, and of course, to NASA. This was, as I said, in 1977-1978.
My set of "Gee-Whiz" statements, printed next to a photograph of the SSME being hot-fired, became a one-page colorful flyer that the Public Relations department distributed to the public. The same layout became the basis for a page on the Rockwell website. The same web page was maintained when Rocketdyne was purchased by Boeing.
Several years ago the "Incredible Fact" about "23 Hoover Dams" was displayed in large letters during a pause in the episode on the Space Shuttle in the "Marvels of Science" series on the History Channel. I was able to buy the VHS tape of that episode.
This is the text of the first paragraph on the web page. This was the first "Incredible Fact" I wrote. It occurs in most of the websites about the Shuttle.
Rocketdyne’s Space Shuttle Main Engine (SSME) operates at greater temperature extremes than any mechanical system in common use today. The fuel, liquid hydrogen, is –423°F, the second coldest liquid on Earth, and when burned with liquid oxygen, the temperature in the engine’s combustion chamber reaches +6000°F – that’s higher than the boiling point of iron.
Again, I wrote the above with help from Perry's Chemical Engineer's Handbook.
Most of my original statements are there. There are a few that were added by somebody over the years for which I take no responsibility for. Here is one example:
“Discharge pressure of an SSME high-pressure fuel turbopump could send a column of liquid hydrogen 36 miles in the air.”
It’s probably technically true, but strikes me as weird. I’ve never seen it quoted.
Some web pages will state: "The maximum equivalent horsepower developed by the three SSMEs is just over 37 million horsepower." My original set of "Facts" did not include any mention of horsepower - intentionally. For rocket engineers, horsepower has no significance; men who drive fast cars like to toss that number around. The critical parameters that determine the usefulness of a rocket engine are thrust, specific impulse (Isp) – which is essentially "miles-per-gallon", and weight.
This additional piece of information on horsepower came about this way: Joyce Lincoln called me one day to report that as a result of the distribution of the press kits, she had been getting many, many requests for the SSME performance in horsepower. I groaned, but made the conversion, and sent the value to her, which she added to "Incredible Facts". At the time, I quoted her the figure as "Brake Horsepower". That derives from the fact that horsepower of an engine was originally calculated by measuring the force exerted on a de Prony (friction) brake. I also ran my figure past Bob Biggs, with whom I worked at the time. He later became a Project Engineer for the SSME, and is quite knowledgeable about the history of SSME development. Bob confirmed my number by deriving it by other means.
As a side note, a few weeks later, Joyce received a phone call from a staff writer for Time Magazine. She didn't know how to answer his question, and asked me if I would speak to him. He called me and asked this: "How can the Shuttle Engine develop 37 million brake horsepower if it has no brakes?" He really did.
I explained to him about the de Prony brake.
I forgot about that effort to support Public Relations, but as the months and years moved along, my words continued to pop up. I would see an "Incredible Fact" used in a newspaper or magazine article in connection with an upcoming shuttle launch or in reports of a completed launch. I have not watched every shuttle launch on television, but on those I have, the narrator usually throws in one of my "Incredible Facts". I assume they do that to entertain the viewers or to fill dead space.
Now that the internet exists and almost anyone can publish information about the Shuttle, the "Incredible Facts" appear more often than ever. They have taken on a life of their own. I came across a website for a swimming pool company that added the information about "draining a pool in 25 seconds". Here is the link:
http://www.elitepools.com/swimming-pool-trivia/
Sometimes the person incorporating the "fact" isn't careful in copying. One website states the engines could "drain an Olympic-sized pool in 25 seconds". Not really.
When I go to the public library or to a book store I will occasionally pick up a book on the space shuttle program (there are a lot). In the section on the engine, the author will usually stick in one or two of my "Interesting Facts". For example, in the book Rockets by Ron Miller on page 81, he uses the fact about draining the pool. In the book The Space Shuttle the author reports this on the Shuttle Main Engines "Each engine produces enough thrust to power 2 1/2 jumbo jets and if one could be scaled down to weight only 3 lb (1.4kg) it would still produce enough thrust to lift a man." That last fact can be derived from the "thrust-to-weight" ratio usually quoted for a rocket engine.
I have cited only a few examples of places where such quotes appear. There are many, more than I have taken time to locate. The amazingly wide dissemination of these shuttle facts is what I believe to be the central theme of this communication to you and for a potential article for the WSJ. I was overwhelmed by the number of places my “Facts” have popped up. To verify this for yourself, if you have a day to spare, go to Google, as I suggested and put in “23 hoover dams” or “drain a swimming pool in 25 seconds”.
"We want some 'Gee-Whiz' words about the shuttle engine," she said. "You know, "faster than a speeding bullet - can jump over tall buildings". She emphasized that I must explain these features in terms that the lay person could understand and be able to visualize. "For example," she pointed out, "I know the engine has a very high specific impulse and an extremely high combustion chamber pressure, but who would know what that means?"
I figured I could squeeze the task in with whatever else I was doing and took the job.
As background, I have to point out that the "rated" thrust for the SSME is 375,000 lbs at sea level and 470,000 lbs at altitude (vacuum). As you may know, the Space Shuttle Main Engine is throttleable - that is, the thrust can be varied from 65% of rated (called "Minimum Power Level") to 109% of rated (originally called "Emergency Power Level" and later re-named to "Full Power Level"). However, the engine had not yet been tested at the 109% thrust level in 1977 because of low performance and engine failures. This was a major concern. In fact, we received a visit in our area by John Young and Bob Crippen, the first astronauts to fly the Shuttle. That was one of the questions they asked us: When will the 109% (Full Power Level) be attained? It was eventually demonstrated in 1981.
The SSME uses liquid hydrogen as fuel and liquid oxygen as oxidizer, the combustion product being steam (water). For the purposes of generating the most impressive numbers for my "gee-whiz" statements I used the propellant flow rates for the combined three engines at the 109% power level. My trusty copy of Perry's Chemical Engineer's Handbook gave me the energy released (Heat of Combustion) in BTUs per lb by the burning of hydrogen and oxygen. The known propellant flow rate in lbs per second easily converts to BTUs per second or watts or any equivalent unit of energy.
Then I spent a day in the company library looking up devices or systems that either generated or used energy with which I could make numerical comparisons. I played around with the power of Boeing 747 jets, with diesel locomotives, with automotive engines. I came across Hoover Dam. Based on the power output of the dam published for that period, I calculated that the three engines developed as much power as 22.97 Hoover Dams, a figure I have not shared with many people (now you know!). I asked myself what that decimal value could possibly mean to anyone other than an engineer; so I rounded it off to 23 Hoover dams.
In brainstorming more incredible facts for Joyce, I wanted to do some comparisons with the very high propellant flow rate. One day I was standing by the desk of Dorothy Rowlands, secretary to Ed Larson, Director of Design Technology at Rocketdyne. I asked Dorothy if she had a swimming pool; I didn't. She said she did.
I asked if she knew how many gallons it held. She told me the precise figure. I asked her how she could be so certain. She told me that if she ever had to empty and re-fill it, she wanted to know in advance how much it would cost her.
Using the volume she gave me, I calculated that the three shuttle engine propellant pumps, at Full Power Level, would drain her pool in 25 seconds. That became another of my "Gee-Whiz" statements.
It turned out to be very popular. Somebody inserted that fact into the Space Shuttle Main Engine page on Wikipedia:
http://en.wikipedia.org/wiki/Space_Shuttle_main_engine
That fact was quoted by the narrator during the launch of the shuttle Discovery on February 24, 2011. Go to this YouTube coverage:
http://www.youtube.com/watch?v=xPkJ8ugK3_0
The quote is spoken about half-way through the narration.
I created about a dozen such comparisons or performance statements. I bundled them up and turned them in to Joyce. She sent them to the Program Manager, Dominic (Dom) Sanchini, and to the Rocketdyne President, Norman Ryker. They both approved the package. Joyce sent me a signed copy for my files.
Joyce prepared Press Kits with my "Gee-Whiz" statements. They published them as "Space Shuttle Engine Incredible Facts" or "Amazing Facts". She must have sent the kits to hundreds of newspapers, magazines, radio and television stations, and of course, to NASA. This was, as I said, in 1977-1978.
My set of "Gee-Whiz" statements, printed next to a photograph of the SSME being hot-fired, became a one-page colorful flyer that the Public Relations department distributed to the public. The same layout became the basis for a page on the Rockwell website. The same web page was maintained when Rocketdyne was purchased by Boeing.
Several years ago the "Incredible Fact" about "23 Hoover Dams" was displayed in large letters during a pause in the episode on the Space Shuttle in the "Marvels of Science" series on the History Channel. I was able to buy the VHS tape of that episode.
This is the text of the first paragraph on the web page. This was the first "Incredible Fact" I wrote. It occurs in most of the websites about the Shuttle.
Rocketdyne’s Space Shuttle Main Engine (SSME) operates at greater temperature extremes than any mechanical system in common use today. The fuel, liquid hydrogen, is –423°F, the second coldest liquid on Earth, and when burned with liquid oxygen, the temperature in the engine’s combustion chamber reaches +6000°F – that’s higher than the boiling point of iron.
Again, I wrote the above with help from Perry's Chemical Engineer's Handbook.
Most of my original statements are there. There are a few that were added by somebody over the years for which I take no responsibility for. Here is one example:
“Discharge pressure of an SSME high-pressure fuel turbopump could send a column of liquid hydrogen 36 miles in the air.”
It’s probably technically true, but strikes me as weird. I’ve never seen it quoted.
Some web pages will state: "The maximum equivalent horsepower developed by the three SSMEs is just over 37 million horsepower." My original set of "Facts" did not include any mention of horsepower - intentionally. For rocket engineers, horsepower has no significance; men who drive fast cars like to toss that number around. The critical parameters that determine the usefulness of a rocket engine are thrust, specific impulse (Isp) – which is essentially "miles-per-gallon", and weight.
This additional piece of information on horsepower came about this way: Joyce Lincoln called me one day to report that as a result of the distribution of the press kits, she had been getting many, many requests for the SSME performance in horsepower. I groaned, but made the conversion, and sent the value to her, which she added to "Incredible Facts". At the time, I quoted her the figure as "Brake Horsepower". That derives from the fact that horsepower of an engine was originally calculated by measuring the force exerted on a de Prony (friction) brake. I also ran my figure past Bob Biggs, with whom I worked at the time. He later became a Project Engineer for the SSME, and is quite knowledgeable about the history of SSME development. Bob confirmed my number by deriving it by other means.
As a side note, a few weeks later, Joyce received a phone call from a staff writer for Time Magazine. She didn't know how to answer his question, and asked me if I would speak to him. He called me and asked this: "How can the Shuttle Engine develop 37 million brake horsepower if it has no brakes?" He really did.
I explained to him about the de Prony brake.
I forgot about that effort to support Public Relations, but as the months and years moved along, my words continued to pop up. I would see an "Incredible Fact" used in a newspaper or magazine article in connection with an upcoming shuttle launch or in reports of a completed launch. I have not watched every shuttle launch on television, but on those I have, the narrator usually throws in one of my "Incredible Facts". I assume they do that to entertain the viewers or to fill dead space.
Now that the internet exists and almost anyone can publish information about the Shuttle, the "Incredible Facts" appear more often than ever. They have taken on a life of their own. I came across a website for a swimming pool company that added the information about "draining a pool in 25 seconds". Here is the link:
http://www.elitepools.com/swimming-pool-trivia/
Sometimes the person incorporating the "fact" isn't careful in copying. One website states the engines could "drain an Olympic-sized pool in 25 seconds". Not really.
When I go to the public library or to a book store I will occasionally pick up a book on the space shuttle program (there are a lot). In the section on the engine, the author will usually stick in one or two of my "Interesting Facts". For example, in the book Rockets by Ron Miller on page 81, he uses the fact about draining the pool. In the book The Space Shuttle the author reports this on the Shuttle Main Engines "Each engine produces enough thrust to power 2 1/2 jumbo jets and if one could be scaled down to weight only 3 lb (1.4kg) it would still produce enough thrust to lift a man." That last fact can be derived from the "thrust-to-weight" ratio usually quoted for a rocket engine.
I have cited only a few examples of places where such quotes appear. There are many, more than I have taken time to locate. The amazingly wide dissemination of these shuttle facts is what I believe to be the central theme of this communication to you and for a potential article for the WSJ. I was overwhelmed by the number of places my “Facts” have popped up. To verify this for yourself, if you have a day to spare, go to Google, as I suggested and put in “23 hoover dams” or “drain a swimming pool in 25 seconds”.