The Black Horse, a layman's view

by Dan Risacher, MIT student

I'm not a Rocket Scientist, I'm a computer engineer.
Essentially everything I know about aerospace engineering is freshman physics, or self taught. I have a lot of interest in access to space, because I want to go there someday. The Black Horse is possibly the most important research being done anywhere on Earth. While I realize that this statement is somewhat hyperbolic, if we don't get off the Earth eventually, we are doomed. As far as I'm concerned, the sooner we get off the better. Only by climbing out of the cradle can we assure our growth and survival as a race.

So why is the Black Horse important? The reason is money. Right now, going to space is expensive; really mondo expensive. It doesn't have to be that way! The celebrated Space Shuttle is built with 1950s and 1960s technology, and we learned a lot since then about how to do things "the easy way". If you or I want to get into space someday, we can only hope that cheaper methods come along. The Black Horse is that way. Ballpark calculations of payload launch costs for the vehicle are less than $500/lb to low Earth orbit, possibly much less. It's hard to calculate the cost-per-pound for the Space Shuttle, but it's closer to $10,000/lb.

Why is the BH a good idea?

• Operational costs will be kept low
  The real reason that current launch systems are expensive is not the fuel or the hardware; it is the cost of operations. Flying a shuttle or a Titan or an Atlas takes big organizations to account for each heat tile (on the shuttle), or carefully integrate payloads `on the pad', or to set up the rocket for launch. The Black Horse doesn't have a special configuration for launch and was designed from the start to have operational requirements like any other plane in the Air Force inventory. All current space vehicles are `expendable' or `salvagable'; the Black Horse will be truly `reusable'. The HTHL design also means that it won't require the expensive ferrying that the shuttle does. Sheila Widnall, the Secretary of the Air Force, has said that making space launch routine and affordable is one of the primary issues of space based warfare, which is why we need a launch system which is afforable and routine to operate.
• Refueling is a great enabling technology & well understood too!
  Aerial refueling has been the single most enabling technology for military aircraft ever, with the possible exception of the jet engine. Essentially all western military aircraft are capable of aerial refueling, because it enables them to do missions which would otherwise be impossible. Why should launch vehichles be any exception? Plus, aerial refuelling is very well understood and operationally routine.
• Efficiency of each stage for two different tasks
  There are several different tasks that a reusable launch system has to perform which require different capabilities. First, it needs to get itself and the tremendous weight of it's fuel off the ground. Second, it needs put it's payload in orbit, and third, it needs to get back down safely. The Black Horse takes advantage of the fact that these tasks are different.
  • KC-135 is optimized to lift 160,000 lbs off the ground
    Any craft that can heft 160,000 pounds of fuel up off the ground is, by necessity, a huge beast; with monstrous landing gear to support its weight on the ground and huge jet engines to get it going. Fortunately, we already have airframes that are designed for this specific task that work well, like the KC-135 and KC-10.
  • BH is optimized to put 1,000 - 5,000 lbs in LEO
    An orbital insertion vehicle needs rockets, not jets, so it can keep going when the atmosphere gets too thin. It needs to be able to fly hypersonic. It needs to be lightweight, because it's lifting all its mass out of a deep well. Also, it needs some way to slow down when it re-enters - such as wings for atmospheric braking. The Black Horse has all these features.
  • It's SSTO & TSTO; best of both worlds!
    There's a lot of disagreement about whether Single Stage technology is a good idea or not, because there is a big benefit from not carrying anything to orbit which you don't need once you get there. Of the MIT Aero/Astro faculty, I'm told that only a small few think a SSTO vehicle will work at all. But lots of other people think that it can be done, such as NASA, McDonnell Douglas, and Lockheed. The Black Horse is great because it is the best of both worlds. It's a single stage to orbit craft, and gets the huge operational benefit of a SSTO, but it doesn't carry everything with it, thus having the prime advantage of staging.
  • Operational Flexibility means high mission rates
    Here's a quote from the 18 September 1995 Aviation Week and Space Technology, p. 21:

    Working on all that [a list of technical issues] with a fully reuseable SSTO in mind will necessarily produce advances that would be applicable to a two-stage or partially reuseable vehicle, proponents contend.

    But the difference in single- and multi-stage systems' operational flexibility could be profound. One Defense Dept. expert on trans-atmospheric vehicles said the Pentagon would easily have hundreds, perhaps thousands, of missions annually for a cheap SSTO. Asked how many times a year the military might want to fly a TSTO, or two-stage vehicle, he said, 'Maybe 15'.

    What this means is that any vehicle which has a high degree of operational flexibility can and will be used for all sorts of things. It means that there's more to SSTO than satellite launch. For example, despite their design mission, fighter jets are used for many types of missions: air superiority, fast attack, reconnsaisance, sentry, training, escort, propaganda, and many others. These roles are possible because fighter jets are robust and versatile. The Black Horse will make a huge leap in versatility by adding trans-atmospheric and orbital flight capability, without sacrificing ease of mission planning.

Why will it actually happen?

• Useful to the USAF, and makes use of USAF assets.
  Flexibility is the key to air power, and air power is the key to victory. A Black Horse would have tremendous military application because it would allow US Space Command to put as many satellites in orbit as they want and, more importantly, whenever they want. Another part of Space Command's mission is the negation of enemy space assets, which can only be done easily with a flexible launch vehicle like the Black Horse. Furthermore, it would put American forces anywhere on Earth within an hour of takeoff. Talk about rapid response!
  The military is the only organization which really has experience with aerial refueling, and they are the only people who have the capability to do it. Thus, since they can maintain control of it, it encourages them to build it. Plus, it uses existing assets, which means that we get more for our dollar.
• Off the shelf hardware == quick build & fly cycle
  As the DC-X program and Clementine have shown, it's much easier to get something working if it doesn't depend on completely new technology which you need to develop. The only really new technology in the Black Horse is the in-flight transfer of oxidant instead of fuel, (which may be harder than it sounds) and possibly the engine design, depending on propellant selected. For some proposed propellants, existing engines will suffice. The airframe follows a fairly traditional fighter design methodology. There are no huge breakthroughs except for combining all the lessons we have already learned into a single vehicle.
• Needs to be space-worthy, not man-rated
  Some people have noted that it is mind bogglingly hard to get a space craft `man-rated', and that the difficulty in doing this will crush any RLV design which puts humans on board. The idea of man-rating a rocket is really from the era of ICBM style launch vehicles which are only used one time, and are therefore hard to prove reliable. Aircraft aren't subjected to this same process; they are instead shown `airworthy', and a vehicle like the Black Horse would fall into that testing methodology, which is much less costly than man-rating a rocket. Each new rocket launched from Vandenburg AFB, is a brand new piece of hardware, and it takes a lot of tests to make sure it's not going to blow up. A fully reusable vehicle only requires that level of scrutiny the first few times it flies. After it flies successfuly a few times, it becomes proven, predictable, and reliable.
• Mitch Burnside Clapp is a really motivated and motivational guy.
  There are do-ers and nay-sayers in the world. Mitch is a do-er. Having met him and heard some of his accomplishments, I believe that if anyone can get a RLV to work affordably, Mitch can.

Why will it work?

• Refueling is a win.
  I already talked about how refueling is a good idea above, so I won't go into it again in too much detail. The key idea is in extending capability, and reducing dV to orbit. Drag and gravity losses can make a big difference to a rocket.
• Wings are a win
  Wings are proven technology. They are well understood. Some people think we should abandon them for space-vehicles, but the discussion is somewhat off topic, so I will forego it here.

In conclusion, I'll say that going to space is a dream that I share with many people. It is not an easy dream to achieve, nor is it one for the short-sighted. I decided that I wanted to go to space when I was four years old. When I was fourteen, I realized that it was hopeless. When I was twenty, I heard about the Black Horse, and decided that if you're willing to work, there's never any good reason to lose hope.

In 1994, Neil Armstrong came to MIT and gave a guest talk in the largest lecture hall at the Institute. It wasn't advertised, but when I got there, it was standing room only. At the end, someone asked him this question:

I was born in 1974. What are the odds that man will set foot on the moon in my lifetime?

When I was your age, I would have said that the odds of man going to the moon in my lifetime were zero.
But we did, so don't lose hope, because anything can happen.

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