Design-challenged

With due respect to the “challenged” individuals who have impediments or roadblocks to performing certain tasks… some days, I feel like I am design-challenged. I may have a fair amount of understanding about a particular design goal and how it might be realized, but I can’t do the design.

To clarify, I operate in a couple of technical domains.  I’m doing fine in one (computer systems, especially computer software). But in the other, I have a sense of extreme frustration. Basically, I can’t do aerospace vehicle design.

I’ve come to the conclusion that to do reasonable design work, you need the appropriate 3D mechanical CAD tools, combined with simulation capability, such as static structural analysis, fluid flow, and thermal conductivity. Back of the envelope computation doesn’t cut it for a design that can be built.

What’s the problem with the CAD tools? They cost on the order of $7,000 for CAD and simulation capability. An aspiring designer cannot afford these tools. (This is not the same as having AutoCAD or Sketch-Up for drafting and design.) From here, the CAD system may generate instructions for manufacturing. In fact, for a more coordinated environment of design tools, database, and interface to manufacturing, the software tools may cost $50,000.

These tools are part of a design workflow. Other components of the workflow might include trajectory design and analysis, high fidelity CFD, design of the fuel system. For a vehicle design to work, the different parts of the workflow need to be able to talk to each other. That is, there are data formats and possibly signals agreed upon between tools.

All this introduces a set of workflow challenges. That is, the design-challenged individual may also be workflow-challenged.

To better size up the problem for a small aerospace entrepreneur, I’m hosting a session on “Aerospace Workflow Challenges” at the Hacker Dojo on June 29. I have more notes on the expectations of the session here.

 

A text-based countdown script in Python

Problem: You want to count down to an event (e.g., a rocket launch). But the web-based animated countdown consumes too much screen space and battery power (i.e., your laptop’s fan turns on when you go to that web page).

Solution: a text-based countdown in a small shell or console window. This one, down.py, is written in Python 3. The project on GitHub is called DownPy.

I’ve tested this on Linux (Ubuntu 12.04) and Mac OS X Mavericks (10.9). It has no fancy appearance, and all it does is count down.  But that’s also why it barely takes any power.

If you want to try this in the next few days, here is an example.  This the command for counting down to the currently scheduled launch time of NASA’s Orbiting Carbon Observatory (OCO-2).

./down.py 2014-07-01 02:56 -z -7:00

If you’re a git user, then you should know how to clone the DownPy project. And if you aren’t, there is really only a single file. Make sure you have Python 3, copy the file, make it executable, and go for it!  Of course, you can also open multiple shell/command windows, and have a countdown for each different event you are interested in. (There are some Mars spacecraft encounters coming up.)

So now you how I spent one day of my weekend.  I came up with the basic date/time queries in Python earlier in the week. Then on the weekend, I created a loop that adjusts to lag and other compute load oddities.  By the evening, I had it reporting and rewriting on a single, non-scrolling line.

[More info on Python, including downloads.]

SpaceX Dragon V2

SpaceX unveiled the manned version of the Dragon capsule on Thursday evening, May 29. (Yes, about 2 weeks ago. [I’ve been busy.]) If you missed it, here is how SpaceX described Dragon V2.

The essentials

Judging from Internet reaction, people seem to be enamoured with it. You can read reactions to it elsewhere.  I’ll give you my impression.

  • The SuperDraco engines, which are used for landing the capsule on solid ground, are also the emergency launch escape system.  Unlike Mercury, Gemini, and Apollo, where the escape tower was jettisoned at altitude after launch, the SuperDraco engines are integral to the spacecraft.  The placement of the engines dictated an altered shape for the capsule. They are presumably evolved from the Draco thrusters used for attitude control, but are 100 times more powerful. (As Elon said, “Hence, the ‘Super’.)
  • The large touch-screen panel, which can stowed away, is new to spacecraft design.  This indicates that the actual avionics which provide data to the display, are located elsewhere in the capsule — a major departure from previous manned spacecraft and aircraft design. I saw some comments that compared it to a Tesla touch-screen display.  I can believe that Tesla might produce some custom components for SpaceX; there is certainly technology sharing going on.  To me, the joystick looks like it could have been designed for a sports car.

Dragon V2 Interior

This is, in my judgement, an incomplete spacecraft, but a really impressive one.  The design is probably complete, but what was on display was a basic functional shell.  It looks roomy because there weren’t seven people in there, and the storage compartments for food and other crew consumables have not been installed yet. (Oxygen and water are likely provided by tanks on the perimeter out the capsule, but outside the cabin.) Presumably, the crew would spend some time in a shirt-sleeve environment rather than in helmeted pressure suits.  There will need to be space to stow suit gear away.

Avionics

Not on display were the avionics and software for how to do a propulsive soft landing on ground. It stands to reason that SpaceX has an ambitious avionics and software program that encompasses real-time attitude dynamics and engine control. SpaceX has been doing landing tests with Grasshopper and Falcon V9R. Now it will add Dragon V2 to that effort.

A lander for Mars?

SpaceX designs most of its hardware with Mars in mind.  It is possible that this fundamental Dragon capsule design could be what lands on Mars.  There are, however, a couple caveats.

  1. The capsule would have to open up to the Martian atmosphere, de-pressurizing to vastly different conditions from what are inside the capsule upon landing.  Martian atmospheric pressure is about 1/100th of Earth sea level. The temperature radically colder than Earth, perhaps comparable in some cases to Antarctica.
  2. If the capsule is to be reusable on Mars, it probably is going to be powered by methane rather than the current hypergolic propellant. Methane can be produced on Mars. Other consumables would have to be produced as well.  That is, there needs to be a ground infrastructure for servicing a capsule before it could be reused.

In the final analysis

This is a low-Earth orbit vehicle for ferrying passengers to station such as the ISS or perhaps a Bigelow station, maintain a crew for at most a few days.  With few crew members, it could stay in orbit for a longer time.

It is a stepping stone in developing technology for Mars, not the final vehicle, but it is a fairly major one. A launch escape test later this year will demonstrate the SuperDraco engines and avionics in flight.


Footnote: Rick’s been busy

For those who wonder, what happened, why did I drop out of sight?, the answer is, I’ve been busy.

Outside of the day job, I’ve been helping coordinate activities on behalf of the Silicon Valley Space Center.  Specifically, we just completed a Space Entrepreneurship Series, a sequence of four meetings for aspiring space entrepreneurs. We consistently had 20+ attendees. Hopefully, this means a bumper crop of new space enterprises in the next year.

My day job is in the software group of a computing hardware design company. Sometimes, I get intriguing challenges, some of which call for really long days just because I can’t stop. The last few weeks have been like that.

To make life more interesting, a couple of space-related efforts I have helped on seem to have attracted attention.  More on those later.