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ORBITER STRUCTURES

March 26, 2017

WINGING IT

To reach orbit in horizontal launch is a challenge.  We need a first stage that is nearly single stage to orbit capable.  Even then we projected a need for the orbiter to make some contribution to the effort.  We had to make room for more fuel to achieve orbit.  As such we may have a slightly larger vehicle for similar payload capacity.  Published data on mass varies widely as some are only targeting limited fuel for orbit and reentry.  And some may publish misinformation too?  Here is how we stack up, in the middle of the pack…ouch that is a big fuel mass!  Well it is being adjusted down real fast now, probably wet mass of 86,000 lbs.  Then we start chasing more mass ghosts!

C29

we have a rough outline of structures to transfer loads when attached to the booster and allow room for fuel.  More details will be added for payload service later.

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FUEL AND STRUCTURES

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ROUGH SCALE TO THE X-37 AT 29 AND 54 FT. LENGTH.

This early X-37 study indicates that they once considered HTP and JP as we are doing now.  Currently the X-37 uses highly toxic fuels that we will avoid.  Besides, we have a source of 100% HTP in Wyoming!

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THE X-38 HAD STRAP ON ROCKETS, LITTLE ON BOARD PROPULSION AS A LIFEBOAT.

We anticipate composite structures rather than the metal frames of the X-38.

C1

WE ARE LARGER THAN DREAMCHASER WITH CONFORMAL FUEL TANKS

Here is an illustration of how high pressure fuel tanks get around structures.  We will use some low pressure with HTP, but we can fit close to the structures.  We do pay a penalty in fuel mass, but hope to reclaim some of that from other components.  Our structures show similar spacing here.  But we lack a crew pressure vessel to aid structures.  We may get some of that from low pressure fuel tanks.

C2WE WILL USE A TOP HATCH INSTEAD OF A REAR HATCH.

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WE ARE SLIGHTLY SMALLER THAN THE (DEAD) ESA HERMES

Our structures are spaced farther apart…were theirs metal?

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AND SPEAKING OF DEAD BIRDS…WE ARE SIMILAR TO ORBITAL SCIENCES PROMETHEUS.

We will be learning more about composite construction as we go along.  Scaled Composites is displaying good examples of this kind of construction.  Compared to metal aircraft they often build large panels with fewer frame structures.  Stressed skin can cover a larger part as seen in this tail section.  Frame reinforcements are built in to the panel.

SS2K

SS2 TAIL STRUCTURES

SS2B

INNER AND OUTER CABINS ARE CONFORMAL WITH FEW STRUCTURAL ELEMENTS.  HOWEVER THERE IS A LOT OF STRUCTURE UNDER THE CABIN IN THESE WINGS.  OUR WINGS PASS AROUND THE PAYLOAD.

C7

Now we see the zones opened up for fuel tanks and engine access.  More changes will follow as we consider skins, and opportunities to use them to reduce structures.  Service access and thermal protection will become issues down the road too.

I expect to find this is still heavy; I got my start designing truck frames!  My model airplane was designed with the same heavy hand.  We found the fiberglass to be so robust that I had to go in and carve a LOT of unnecessary structures out!

IMG_4557

This leads to a valuable point: no one could possibly deliver a complete launcher design single handed.  We know a series of vendors who can build prototypes.  They will be straightening me out as we go along.  This is a look at the future that will only come in steps, with collaboration from all over.  There is a pit that stumbles a lot of “new space incubators” that only encourage business in their own state.  Sorry, that’s a STINKUBATOR.

We publish this to motivate consideration of new solutions, and a lot of vendors have ideas waiting for us.  We can expect a consortium of new and old space technologies to be involved to deliver goals.  It will not come out of tiny teams or geniuses.  How long did it take us to discover the “Hidden Figures” of NASA history?  It needs big teams, big dreams, and big bucks.

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As a draftsman I used to deliver blueprints to the shop, but now we can deliver vision to the next generation.  My illustrations are pointing out both the open and closed doors.  These are based on somewhat reachable new and old technologies. We paint a future for the bold to explore.  If Gene Roddenberry’s “Star Trek” inspired engineers, than we of industry can do the same.  It’s only a paper Airplane, but Low Earth Orbit is important.  “Once you get to earth orbit, you’re halfway to anywhere in the solar system.” Robert A. Heinlein  We can’t afford to have unaffordable orbital access.

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It’s only a paper airplane, on the way to a paper moon!

 

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2 Comments
  1. Douglas Drummond permalink

    I like your comments about the structure. Perhaps you have made more progress on minimizing the “inter-stage” structure. I noticed most of your comparisons were with suborbital vehicles such as Space Ship Two and Lynx: Of course an orbital vehicle will be MUCH bigger. The delta-V of the orbiter stage is enhanced by the small size of the orbiter and the lighter weight, especially when low on propellant mass at the end of powered flight. >>> Doug

  2. Douglas Drummond permalink

    With respect to propellants, remember that a pure rocket carries ALL its reaction mass. Higher density propellants, such as HTP are not necessarily a bad thing. They increase the mass ratio while keeping the tanks smaller (and therefore less massive), and further improving the mass ratio. The natural logarithm of the mass ratio is probably the most important factor in the rocket (delta-V) equation. Similarly, the first stage benefits greatly by using “mixed cycle” engines so that it *does not* have to carry all its reaction mass.

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