guest blogger john hare
Work has picked up for us in the last several weeks, so I have been focusing on trying to make money instead of posting anything. Second reason for not posting is that several of the people that responded to my concept posts managed to effectively challenge the ideas in ways that I hadn’t expected. There was a far higher quality of critique than I usually see without writing a check. Continuing on with further possibilities on a concept in doubt is not very attractive, unlike throwing something controversial up once or twice. Over half the ideas on my short list of ideas to post now have known possible flaws that I have to rethink before moving on. Thank you to all the people that managed to get through to me exact problems in my conceptual visions, and to the ones that added to the ideas.
I had something of a grand scheme for a systems approach that seems to be better than most concepts I am aware of, to me at least. By breaking things down into the smallest subsystem I could describe, many answers to questions I hadn’t thought of came forth. I believe that if I had simply tried to throw the whole thing out there at once, it would simply have been dismissed (properly) as another flawed champagne idea on a beer budget. The accurate information to divert me to other channels wouldn’t have happened.
The short version of the total idea was an HTHL flyback stage with a second stage that hits a tether. Both stages torus tank based with the upper nested in the donut hole of the first. Two tipjet propellers on the first stage to provide cruise thrust and wingtip vortex control to get the induced drag down. Cagejet tuborockets in the vertical tails of the first stage for drag compensation and thrust to mach 1.6 (lightweight intake limit), with very high pressure, altitude compensating rockets kicking in at 20,000 or so feet and mach 0.6. Second stage uses whole bottom of vehicle as very high ratio aerospike from mach 6 to tether at mach 20. Tether reboost with 750 second tetherrocket. And so on
In fighter aircraft there is a term called target fixation with a pilot so focused on his target that nothing else matters. Sometimes that focus results in getting kills, the scoreboard of fighter warfare. A high level of focus is required to hit a high speed twisting turning target. It has been noted many times that successful pilots are hunters, not hunted, and a very high level of self confidence is a job requirement. That only half the participants in a successful dogfight fly away is simply not useful information.
Sometimes that focus results in getting shot down himself by the people on the other side that he excludes from his attention. Without a wing man or warning system that he will listen to, fighter pilots have an even lower life expectancy than normal with unfriendly people doing their best to do it to him first. When your buddy is yelling break break, it’s time to slam the stick over, stomp some rudder, and dump chaff and flares.
I am seeing a lot of this behavior in the rocket business, with many organizations so fixated on one target that they simply cannot see the guns on their six, and won’t listen to the people calling the break. Target fixation is a useful concept in the rocket business to distinguish between concentration on getting a job done, and setting yourself up for failure. The cannons of the fighter have a parallel in the march of technology, and the capabilities of the competition. Your business can be shot down by another company that is faster, smarter, or more agile in delivering what the customers want. The technology is simply one of the tools they use to get on your six.
The Griffenshaft is the most visible example at the moment, with billions poured down a rat hole of a flawed concept. The dozens of groups and members of his own calling the break seem to be unable to get his attention. The target fixation prevents the consideration of the quality of the target, whether there is a better target, and even if he is going to run out of fuel/funding pursuing this one. It is even worse if the wing men know they will be grounded and lose flight status if they call the break and interrupt his concentration. You wouldn’t mind him getting shot down so much if he wasn’t taking so much useful hardware down with him.
Commercial space has a few target fixations of its’ own that just might need to be addressed. I share in several of these so if I am pointing a finger, there are three others pointing back at me. The question in each case is whether we need to call a legitimate break, or if we are distracting people trying to make the shot.
Hydrogen is high on the list. I have joined many others in saying that hydrogen is more trouble than it is worth in almost all cases. Jon has pointed out that there are examples of existing hardware that are mass competitive with dense fuels for upper stages.
Clustering modules is very popular. Develop one stage properly and cluster as many as you need to get the job done. While attractive in some ways, getting 20 or more stages to play well together all the time seems like it might be tougher than building a bigger vehicle. Some very smart people are on both sides of this one.
The single massive, do all rocket is one that comes up all the time. The Shuttle replacement or the Saturn replacement or the you name it is a dangerous fixation if a really good use for it is not justified. I think Kistler bit it on this one.
Pressure fed for simplicity is a standard for most newspace companies. You know where I stand on that one. With the rocket equation being what it is, a pump seems to be the inexpensive option compared to the sheer size penalty for low pressure orbital rockets. I have also seen plenty of complexity in the so called simple pressure fed systems. I never heard of a battery powered pump for a rocket until Paul started working on one.
High tech gets high performance. Sometimes high tech is just gingerbread. If it is not really needed, don’t waste your money trying to get wall to wall data on a pig that is designed wrong to begin with.
ELVs being cheaper to develop is getting busted now, though some still believe it is cheaper to analyze problems than to test them. I don’t really care to depend on a vehicle with no flight history after a test flight program of perhaps two flights by similar vehicles.
Vertical takeoff being lighter could possibly be flawed. A standard ELV on a runway trolley on a slight incline could possibly improve performance and reduce vehicle mass slightly. Side benefit is less ground infrastructure and therefore more potential launch sites.
Simpler is cheaper an more reliable. Not always.
There are many assumptions out there that really need to be examined. Focus on a single objective can result in making that objective, or in getting shot down by the competition that you ignore. Having been shot down in business a few times myself, I hope my friends out there have good wing men watching their six both technically and financially that they will listen to. I also hope the jamming from us wannabes doesn’t distract them from good targets.