Capsule Que Pasa

I was jolted a bit when I read the amounts and requirements for commercial crew last week. Not that Boeing got more than SpaceX, but rather that $6.8B is budgeted for a developing a couple of commercial capsules to fly on existing launchers. Boeing’s $4.2B doesn’t bother me as it should be expected of traditional contractors, SpaceX’s $2.6B does.

I am not going to suggest that human transport vehicles to LEO should be trivial or cheap. I do suggest that SpaceX requiring $2.6B to finish development of  a capsule that is supposedly almost ready to go, even including the maximum 7 flights, is well out of step with the reported development costs of that company. It has been said quite often that SpaceX developed the Falcon 1, Falcon 9, and Dragon 1 for under a billion dollars.

My question is, why should capsule development cost on the order of triple that of an entire Falcon 9 launch vehicle? This is not to trivialize the work to be done, or the paperwork involved, but seriously asking what is so complicated and expensive inside that vehicle that drives the cost far beyond that of entire launch vehicle families?

This post might be considered snark. That is not the intention. It is a serious puzzle that affects development of the solar system. A puzzle that I can’t yet understand. I am not real interested in the standard NASA bashing response of how the government drives up costs that we have all rehashed a hundred times. I am interested in any solid information on the hardware/software cost drivers of this bus without a main engine.

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CCtCap and Blue Origin/ULA Article on SST

I just did a guest post on the Sic Semper Tyrannis blog on the CCtCap and Blue Origin/ULA announcements. They’re aimed at people less familiar with space news than most Selenian Boondocks readers, but I figured I’d link to it so I can say I’ve done at least one post on this blog this month… :-)

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VTSL Vehicle

I got into a discussion the other day about the Blue Origin/SpaceX barge landing issue. I suggested that it was very difficult to write such a comprehensive patent that there was no way to design around the restrictions. As an offhand illustration, I suggested that landing on a hovercraft was unlikely to be covered by a barge landing patent. Being called on it as an idea instead of mere talking point, I did a quick search to refute the point of hovercraft not having the capacity to handle the weight.

The two craft that remembered from TV documentaries I found in minutes. The Marine Corp LCAC is the Landing Craft Air Cushion and is rated for 60-75 tons and 40 knots speed. The operational radius apparently 200 miles. The English channel ferries that were retired after the Chunnel opened for business were rated for 52 cars and 60 mph. It is likely that there are hovercraft in these performance ranges available for sale in the world without having to build your own.

The point I couldn’t address was whether hovercraft of any size would be stable enough for a landing at sea. I didn’t find any definitive source on the relative stability of these vessels compared to anything else.   In order to raise this thought to at least idea level I decided to assume that they could not be stable enough for the conventional landing we tend to think of.

The idea of any landing is to get the vehicle down without any damage whatsoever. This covers everything from model airplanes and rockets, to airliners, VTVLs,  and Space Shuttles. Even a hovercraft like the LCAC capable of carrying an Abrahms tank wouldn’t seem to have the excess capacity for a full landing platform capable of landing a rocket stage and securing it against the rolling and pitching from even a fairly mild sea state. Horizontal landings of a serious rocket stage a la aircraft carriers is so absurd as to defy serious thought.  I came up with the slant landing technique, as demonstrated by Masten Space Systems during the Lunar Lander Challenge.

So Vertical Take off and Slant Landing is VTSL. When Masten was testing vehicles in the Mojave wind, sometimes the vertical landing vehicles would be, I’ve read, leaning 20-40 degrees from the vertical to compensate for the extremely high winds for precision landings. An LCAC at high speed will produce relative winds of as much as 40 knots  (46mph,I think) plus the natural wind component for a total wind across  the deck of 50-70 mph. A stage landing on the fast moving vehicle will be leaning into the wind just as the Masten vehicles did. A net on a pair of pivoting booms could match the angle of the incoming stage to catch it at near zero relative velocity in a three axis capture.

LCAC Lander

The whole length of the vehicle could be soft netted simultaneously to avoid any ten story structures falling to the deck. As soon as netting secured is confirmed the hydraulics retract to the horizontal for the trip home. Being a hovercraft, the destination is inside the stage integration building instead of the barge dock. It seems likely that the listed 200 mile range of the LCAC is fully loaded with dangerous people and their tools. The hovercraft going for a stage capture could make the trip out with bladder tanks in the cargo area for a massive range extension

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Asymmetrical Payload Boost

Paul451 made a suggestion on the last post that triggered a thought on boosting payloads on many current vehicles at a reasonable cost. I claim 50% credit for this concept with Paul getting the rest.

He suggested that the tanks on the last post should be thin walled balloon tanks with a structural truss from the thrust structure of the first stage to the second stage. This would allow modular stacking and swap outs with minimum pain. It would also allow greater flexibility in modifying vehicles for different missions. The thin wall tanks were to compensate for the mass of the structural truss as well as for cost reasons.

My quibble was with the truss mass, though the ability to go with cheaper and lighter tanks appealed greatly. My thought based on his thought started with using an existing LV for the structural truss with the thin wall tanks attached to the sides much like in the previous post. Then SRBs are attached to the outsides of the strap on tanks. My squeamishness about SRBs is not shared by several of the experienced companies that actually launch rockets.

Paul451

Several companies use strap on SRBs as a matter of course. The Atlas sometimes uses a single SRB, which answers many of the concerns expressed in comments about asymmetrical loads or thrust vectors expressed in the previous post. A variety of existing and well known SRBs are available to launch companies right now, as opposed to the liquid engines that I would prefer. SRBs are frequently mentioned as relatively inexpensive engines. My qualms have to do with the unfortunate failure modes.

If two tanks are strapped onto an LV with direct feed to the core engines, the core will be far too overloaded to leave the ground. Add enough SRBs to the outside of the strap on tanks and the vehicle will have the TW to launch. At SRB burn out, the core vehicle’s engines will be at full vacuum thrust. A lofted trajectory will allow the total vehicle to have a TW of less than one including the strap on tanks. The vehicle first stage mass ratio from Mach 3-4 and 25 miles could be as much as double that of a standard core vehicle doing a ground launch. Payload could triple or so.

An Atlas 5 with this modification could match the theoretical payload of an Atlas 5 heavy with the expenditure of one RD170 instead of three.  Other vehicles run by companies not squeamish about SRBs could get similar results.

As pointed out by Peter in the previous post, it is not required to stop at two strap on tanks as the Saturn I for instance had multiple parallel tanks.

In the event of SRB cato, the strap on tanks act as shrapnel catchers. This might make it possible for standard LVs to use SRB boosters with less concern about losing the core vehicle and payload. The payload might make it into LEO instead of GEO after losing the extra boost and propellant.  A tug could be designed and tasked to rescue these stranded vehicles and take them to their intended destination.

 

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Asymmetrical LV

There are several limitations on the ability to expand a launch vehicle past certain sizes. One of them is tank diameter. On the smaller launchers, diameter limits might be dictated by available pipe sizes. A step up from there and tank diameter might be limited by available tooling. A couple of steps up from there and ground transport becomes an issue. Too large and it becomes somewhere between inconvenient and prohibitively expensive to transport from factory to launch site. Another limitation is height and fineness ratio. A launch vehicle gets into problems when the stack length is too large a multiple of tank diameter. 8″ irrigation tubing might be a good basis for a 10′ rocket, but gets into trouble before it reaches 20′. By the same token, the Atlases, Falcons, and similar vehicles are probably very close to the limits of length in relation to diameter. The standard build for a launch vehicle is, starting from the bottom, engines, fuel tank, inter tank structure or common bulkhead, LO2 tank, inter stage adapter, engine, fuel tank, inter tank structure or common bulkhead, LO2 tank, and payload. This is all in one long skinny cylinder except for a hammerhead shroud. To make the launch vehicle larger requires either more diameter, more length, or both, with the  manufacturing and transport problems from the diameter increase, or the structural problems from the length increase. There might be a way to double the size of a given vehicle class while holding the costs and other problems down. This idea is to build a vehicle that is asymmetrical around existing tooling. Also use a modular assembly technique to avoid both transport problems and the necessity of new tooling or construction techniques. Asymetrical LV   I still don’t have a computer that lets me draw cartoons all that well. The sketch is two possibilities for the vehicle concept. A stretched LOX tank built on existing tooling  that is as long as the original entire first stage. A stretched Kerosene tank proportionate to the LOX tank also built on existing tooling. These tanks are trucked separately to the launch site where they are clamped together along with the thrust structure. On the left the sketch has the helium tanks, avionics and such in the space above the shorter Kerosene tank with the second stage above the center line of the vehicle. The figure on the right has the second stage nested above the Kerosene tank with the helium tanks and such moved elsewhere. If this concept is feasible, a first stage could effectively double in size without causing problems in manufacturing and ground transport. Engines would double in number, but dome tank ends would not. The increased cost of the larger vehicle would be dominated by the engines. Eliminating the inter tank structures would eliminate a place for fumes to gather and possibly cause problems. The tank connectors could easily be lighter and cheaper than the normal inter tank structure. There would be no place at all for potentially explosive fumes to gather, which means that a leaking tank might be less of a problem. By going modular, any problem section could be swapped out with relatively little effort. The four modules being LOX tank, Fuel tank, thrust structure, and second stage. Two of these units could be flown together in a quad layout. Three of these units could act as boosters/first stage for a conventional  vehicle centered between them in the seven tank hexagon layout.

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SpaceX and Sea Launch

Another speculative thought. Suppose we have all been assuming that Falcons will try to land on a barge at sea or accept the payload penalty of RTLS, when all the tests have actually been in support of a launch at sea to a land recovery.

Sea Launch has the sea going craft to launch large rockets at sea. They are also, according to rumors, not making quite as much money as the investors would prefer. It seems possible that they might be at least semi-motivated to sell off the under performing launch assets.

What if the real intention of SpaceX is to acquire those assets at bargain prices for use in house. Launch a few hundred miles at sea from Vandenburg for a feet dry landing there, with the actual launch location dictated by the desired launch azimuth. The first stage would never have an IIP intersecting property on land, while the second stage would have an IIP that moved fast enough to minimize theoretical injury and property damage probabilities. A day out to launch and a day back. Twice a week seems possible.

From Brownsville the trip would be even shorter. A quick run to a point that gave the right launch  azimuth and distance from the cape for a Falcon recovery there. Possibly a day trip with the launch frequency that implies if the business develops.

 

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Falcon III H (R)

The vehicle SpaceX lost the other day has been described as a Falcon IX R with three engines. It is a bit intriguing to speculate on the purpose of three engines as opposed to the nine of the full up stage, or the one of the Grasshopper I.

The first and most likely thought is that more than one and less than nine are needed for the test flight profile. So three are required to do the job, but there is no financial sense in tying up, and possibly losing, six additional engines that are not required for this particular test program. The problem with that explanation for us in the peanut gallery is that it is boring and gives us nothing to speculate about.

An explanation that I find more fun and interesting is that there might be a financial and technical case for a three engine Falcon. A shortening of the stack for the lighter vehicle would produce a lower profile for a possible reusable version. Landing on a barge at sea would be with a vehicle with far less bending moments that a full Falcon IX stage. It seems possible that such a vehicle could land (barge) in a much heavier sea state than the larger vehicle. If that is a actual possibility, then Falcon III boosters could be attached to a Falcon IX stack with very low costs per mission if the mini boosters could be reused quickly and often.

Even a first take on such an arrangement yields some suggestive possibilities. A 66% increase in take off thrust would allow as much as 66% more take off mass and slightly more than that increase in payload with the additional staging event. With cross-feed, the Falcon III stages would drop off at under a minute and a half, barely supersonic, and fairly close to the launch site for a quick booster RTLS. The fully fueled Falcon IX would be in near vacuum conditions by that time with the considerable gain in Isp compared to a ground launch. A payload gain of over 2/3 for minimal cost could not be ignored if technically feasible.

For flights where the basic Falcon IX has enough performance to do the primary mission, but not enough for any recovery options, the Falcon III boosters could up the propellant reserve to allow core stage recovery. Small, quick turn around boosters enabling the recovery of a core for certain missions would be a nearly slam dunk decision if technically feasible.

For some Falcon IX missions, a Falcon III heavy could possibly deliver a bit more payload with the same number of engines. The engines being one of the major expense items could make not requiring more of them a sound business decision if the staging events become safe and routine enough. The extra payload would come from the same nine engines powering the stack for the first couple of minute as the normal Falcon IX, after which the two boosters drop off with the consequent dead mass reduction for the remaining stage. The remaining Falcon III would have the same velocity and remaining propellant as the base Falcon IX at this point, but would be boosting 1/3 of the engine and tank mass along with the upper stage and payload.

Last thought is on the difficulty of RTLS of stages entering from far down range. A barge landing is often mentioned, virtually always coupled with the words “good sea state” in some manner. This means that barge recovery is permanently dependent on  the sea not being too rough.  Some missions could be delayed by days or weeks to let the waves subside from a previous storm. Some whole seasons could be off limits if the recovery is sensitive enough.

The helicopter recovery I suggested a couple of years back might bear revisiting for lighter stages. The major objection to snagging a Falcon IX core in the air with a helicopter and flying it back to launch site was the excessive weight of the stage. A Falcon III stage might be air recoverable in a way the the Falcon IX stage could not be.

 

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Andrew Peregrin Goff

There are probably less than 5 people in the world who a) care about my family life, b) don’t follow me on twitter, c) don’t follow Tiffany on Facebook, d) didn’t get an email about this already, but e) do read this blog. So for those of you who fit in that category, I’d like to announce the birth of our son Andrew Peregrin Goff. Andrew is our fifth son after Jarom (deceased), Jonathan (9yrs old), James (7), and Peter (5).

Andrew was born this Wednesday evening at 5:20pm in Boulder. He was two weeks early (but still technically full-term), 6lb 11oz (3.03kg), and 19in (48cm) long. He’s doing great, and both he and his mother are home as of this afternoon.

If you’re wondering about the name, Andrew is my middle name. We also have several friends with Andrew as a first or middle name. It also fits with Peter, James, and Jonny (sort of) as a sort of semi-intentional Apostolic naming theme. We debated a lot of middle names–Andrew is somewhat tough to find good middle names to go with. Our two finalists were Sheridan after Tiff’s dad, and Peregrin (yes after Pippin from Lord of the Rings). We ended up going with Peregrin in the end. The good news is that with a middle name that can be shortened to Pippin, he’s set whether he’s a LOTR-fan nerd like his dad, or whether he gets into basketball…

After having picked the names, we found out that Andrew means “manly or brave”, and Peregrin (which amusingly enough was the word of the day on dictionary.com today) has connotations of wanderer, traveler, etc.

His current nicknames are spud, french fry, burrito, and self-eating-burrito.

Here are some pictures of baby Andrew:

AndrewGoff_JustBornIMAG0435IMAG0439IMAG0443IMAG0444AndrewEatingSelfCarSeat

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Dragon Tug

With the Dragon capsules fully capable of ISS interaction now, how hard would it be to use the dragons for ISS tugs as is?

One of the quite useful pieces of on orbit hardware is a space tug that off loads the critical maneuvering capabilities from the launch vehicles. A launch vehicle that does not need those capabilities will be simpler and cheaper, not to mention safer, than one that does require all the bells and whistles. I am wondering if the capability to accept cargoes from multiple  suppliers for the ISS has stealthed its’ way into operational use without any of us noticing.

It would be interesting to know if Atlas and Delta, or even Sea Launch and foreign suppliers, could deliver payloads to just outside the exclusion zone for a Dragon to tug to ISS. Financially it wouldn’t seem to make sense. Politically though it might get several more players pulling in a positive direction. If it suddenly became blindingly obvious that several suppliers could safely and reliably surge major tonnage to an orbital berth, the argument for the Big Rocket would take another hit.

 

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Ironic

So I’m sitting in a friends yard watching the Blue Angels give it their best at the Sun-N-fun fly in thinking about how to modify their propulsion while all the people around me are oohing and aahing. Same with the F22 demonstration and various prop planes. I guess some of aren’t meant to watch these super skilled pilots do phenomenal things without focusing on the hardware.

Doh

 

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