Thursday, November 20, 2008

Back to Basics

After the abysmal failure of my carbonated soda tests, I went back to the drawing board and rethought the whole concept. I finally realized that I'd been a bit too ambitious, and needed to get back to basics.

Since plain old bottled water is already deployed in the cabin during ZeroG flights, I decided to build an experimental platform that would permit me to get good video (both regular and high-speed) of water spheres. I needed something that would let me get good images of fairly large blobs of water that were floating freely in the cabin, and also let me collect the water at the end of the free-fall segment. Here's what I came up with...

The vertical frame mounts the camera and operator handles, and will also contain a set of high-intensity LuxStrip LED light bars to provide the light needed for the high-speed camera. The horizontal frame is the liquid-collection device, which is constructed out of plastic sheeting, the remains of 5 disposable diapers, and, of course, duct tape.

Everything is constructed out of T-slot extrusions and connectors from Amazing Robotics plus a few bits that I hacked together in my workshop.

The nice big red handles are perfect for controlling the device, pointing the camera, and wicking up the water afterwards.

The diaper+plastic sheet can be removed and replaced in flight; it attaches to a UHMW base plate via some velcro tabs.

Finally, the whole thing folds flat; locking and unlocking is controlled by two wing-nuts; no tools required!

Needless to say, if I can come up with an acronym for this device that matches a major diaper brand, the sponsorship opportunities are literally out of this world ("4 out of 5 incontinent free-falling mad scientists prefer Depends").

PS: Some things I learned while abuilding...

T-slot extrusion is great for these kind of prototyping projects; here are a few things I learned along the way.
  • Most of the supplied nuts and bolts are 10-32. I happen to love 10-32 cap screws so I replaced them with some nice buttonheads.

  • The big red handles use 1/4 bolts; the problem is that 1/4 nuts won't fit in the extrusion. The solution is to use flat automotive speed nuts and a little hackery. Speed nuts are weird spring-steel flat plate devices, and the 1/4 ones almost but not quite fit in the slots. To get them to fit, you do the following: thread a junk 1/4 bolt onto it (the bolt may get a little mangled), clamp one end in a vice, and use a tightened-up adjustable wrench to take the bow out of the nut, so it's pretty much flat. Once you've got it to where it will slide easily in the slot, remove the bolt and test out another one to make sure that the little fingers that grasp the bolt are not too loose, and not too tight. You may have to adjust them with the vise or pliers.

  • A length of piano hinge with holes that are the right size for 10-32 bolts (any hardware store will have some, you can cut it to the length you need) will fold so that the sides are close to parallel if you secure it by alternating 10-32 buttonheads + a small washer (so that each buttonhead touches an empty hole on the other half of the hinge).  The buttonheads act as spacers.

  • The plastic corner connectors have fingers that have starter holes for small set-screws (you will understand what I mean if you get some). However, the cube-corner connectors (not actually used in my device) have one set of fingers that don't have the starter holes, probably because of a limitation in their manufacturing process. Just stuff the no-hole fingers into a bit of the t-slot extrusion and drill your own in using a #41 or so drill bit. Update: I've been told that you can also screw the set-screws into the ends of the fingers without drilling.

  • One of the big pains with T-slot extrusion is when you realize that you need an extra square nut in a section to mount something, because this means you have to take things apart -- unless you know about a trick. It turns out that the 10-32 square nuts have enough variability in their size that some of them can be inserted directly into a slot. To find nuts with this property, slide a bunch of them into a slot, turn the extrusion so that slot is on the bottom, and shake the nuts back and forth; the special secret nuts will drop out. Repeat the process with the remaining nuts rotation 90-degrees, as usually only one axis is short. Set these nuts aside for emergencies. To insert a nut, put it into the slot, put your finger on it, turn so the slot is on the bottom, and slide the nut back and forth; it'll seat itself quite easily (assuming you've got the orientation correct, a 50-50 shot).

Sunday, November 2, 2008

High-speed video LED lighting tests

One of the important supporting projects I have been working on is developing a better light source for the Exilim EX-F1 camera.  As you may recall, on our first flight, we depended on getting light from a cabin window, but this placed a lot of restrictions on freedom of movement, which is important because if you are strapped down, your apparatus isn't always in microgravity; it depends on how good the pilot is at flying the parabola.  If you are freely floating, on the other hand, any variations just cause everything to wobble together, so other than some minor effects due to friction with the air, everything will be very close to zero-g as long as you don't hit a wall, and nobody hits you!

Therefore my plan is to build a portable light source for the camera.  Typical video camera lighting systems start at over $100 for a 10watt halogen system, so I figured it would be more fun to build my own using multiple 3watt luxeon white LEDs from SparkFun (they also have some nice heatsinks for these nasty little critters).

Here's some video of the first test runs, which are very encouraging.  I soldered up 8 3watt LEDs to heatsinks, put them on a styrofoam ring, and wired them up in parallel to 3 1.2v NiMH cells (so I'm actually undervolting them a bit).  You have to use NiMH or NiCd for this kind of application because non-rechargable cells just can't source the current needed - probably 5 or 6 amps total.

Epic Fail!

The initial tests of my 2D Menticulator device failed in so many ways, it's just not funny!

To start with, the pneumatic cola dispensing system doesn't work -- because the bladder used to force the cola out of the bottle acts as a massive nexus of nucleation sites. As soon as you try and put the bladder into the coke bottle, all the CO2 comes out of solution! Foom! So unless I can come up with a system that either avoids the problem or can repressurize the bottle with C02 to put it back into solution, all the lovely pneumatic gear I cobbled together is useless, at least for the purposes I originally intended.

And to make matters worse, even careful attempts to decant the soda into the 2-D menticulator failed miserably. Despite being made with panels of carefully cleaned acrylic, it is rough enough that most of the CO2 comes out of solution and sticks to the walls, both reducing the amount of CO2 available for menticulation and obscuring the view of the convection process. Again, I'd have to repressurize the apparatus to force the gas back into solution.

I think the video I shot of the final test says it all. What happens at the end is just icing on the fail cake, so to speak.

I therefore find myself compelled to choke out the hateful lines, "Curses! Foiled again!"

On the bright side, I have yet to have to utter the deathless lines that doom an Overlord to eternal ignominy -- "I would've have gotten away with it if it wasn't for those meddling kids!"

In other news, work on a LED-based lighting apparatus for the Exilim camera is proceeding fairly well; I'll be posting on that soon.

Friday, October 10, 2008

A Pneumatic Cola Dispensing Manifold

It has been a while since my last post, for which I apologize. I've been busy dialogue-editing an interesting Japanese film about the Special Attack Forces (aka the Kamikaze). But during spare moments I've been working on an improved method of dispensing cola from a 16oz bottle.

Here you see the cola dispensing manifold before assembly. One side of the T-joint is the gas input, which feeds the gas down into the bottle through the cap and into a balloon using some tubing. The displaced liquid goes back up through the joint and out the other side of the T, flowing around the gas input tube.

As I had to get the hole in the cap right in the middle to avoid having the nut on the inside catch on the neck of the bottle, I used my Sherline mini-lathe to get it as close as possible. The cap deformed a little bit when clamped into the lathe but the hole was centered to within a millimeter or two...

The components were bolted together, and I used teflon pipe-wrap tape to ensure that they were gas and liquid-tight. I also put some silicone sealer under the big washer to make sure the cap hole would not leak.

Here is the device completely assembled. As with my previous experiments I used a punch-balloon as the bladder.  Both the bypass tube and the tube inside the bladder had some notches clipped into them to ensure that there were multiple outlets, eliminating the chance of an outlet getting blocked.

As you can see, it inflates very nicely...

My current thinking is to have multiple cola bottles (with manifolds on each) as well as multiple gas bottles, with a piping and valving system that provides redundancy.  Everything will be assembled onto some perf-board that is sized to fit in a rolling carryon bag.

Oh, and I've built a 2D Menticulation test chamber as well, which I'll probably test out this weekend.

Monday, September 22, 2008

Pneumatic Soda Deployment Device Improvements (Part II)

A quick trip to the party store this weekend provided me with a variety of balloon styles to play with.  The best candidate so far is a "punch-ball" balloon, which is both much thicker than a normal balloon and is also pleated.  The fill tube extends into the neck of the balloon right down to the tip, which makes it easier to insert the whole assembly. Also, before inserting the balloon, I pop in a short length of polyethylene tubing that serves as a bypass and allows soda trapped under the balloon to escape.

The system permits quite precise deployment of the soda, although I am still considering implementing a flow restrictor. In the second image, I've deployed soda most of the way up the tube but halted it at that point. By fully expanding the balloon I can expel almost all the soda, although in practice I'll only need to display a few fluid ounces.

One possible improvement might be to use a smaller bottle and a tube sized so  that when the bottle is completely empty, I have a soda globe of exactly the right size.

Wednesday, September 17, 2008

Cola Deployment Improvements

Finally managed to make time to do more testing of the Mark II Cola Deployment Device. Following up on a suggestion that I consider using a small bike pump as the pressure source, I started playing around and came up with this test apparatus.

The basic idea is that the pump is used to pressurize an empty 1-liter PET bottle that contains a couple of balloons that serve as a quick-n-dirty pressure indicator. These bottles can take quite a bit of pressure before they go bang, certainly much more than you can get into them with a hand-pump.

Then a valve is cracked to blow up the balloon inside the cola bottle and expel the cola.  It's pretty controllable but I'm probably going to put in some sort of flow restrictor to make it more controllable.

All of the tubing and fittings are available at Lowes or Home Depot. The tubing is (iirc) translucent semi-rigid polyethylene -- the other option, clear vinyl, doesn't work as well with the fittings.

The fittings themselves are simple $2-4 plastic push-on, quick-release fittings. Amazingly, these are almost totally gas tight!  I pumped the reservoir bottle up to 4 or 5 bar and left it overnight and the leakage was negligible. These things are like legos for low-pressure pneumatics! On the other hand, the brass compression fittings you'll find in the same aisle at the store are a pain to work with -- very hard to get gas-tight.

Tip: some of the fittings have threads on them, which can be very handy (I added such a fitting to the cap of the 1-liter bottle, for example). However, these are pipe fittings, so they have NPT threads on them, which are different from regular UNC/UNF threads used on common nuts and bolts in the US. Even my usual black-market nut connections couldn't fix me up.  However, I eventually found my way to the illegal nut dealers at Steven's Hardware here in Wilmington, where I learned the magic word. The magic word is "lamp nuts" -- for some reason, they use NPT threads!

The major remaining design issue is the balloon inside the cola bottle.  Sometimes it gets caught on the sides of the bottle and this results in another part of the balloon getting stretched until it breaks. I am currently using double-balloons but I'm thinking that finger-shaped balloons will work better.

I've also been working on a 2-D Cola Convection Display Device, I'll post on that soon.

Wednesday, September 3, 2008

Mark II Menticulator Cola Deployment Device Tests

Please go down two posts for the original report on our first experiment -- thanks!

As mentioned in the post reporting the results of our initial microgravity tests, the Mark II Menticulator will require a more sophisticated method of deploying a nicely sized sphere of soda. My initial thought was to use a water balloon, but an afternoon of sweaty testing on the back porch lead to the discovery of several serious problems with this approach.

The first is that when the balloon ruptures, friction between the skin of the balloon and the water results in significant spray, some of which is clearly fast enough to overcome the surface tension of the water (and remember, the soda will have a lower surface tension because of the sweetener and other ingredients). If some of this spray coats the camera port, we may not be able to see the reaction. I did multiple tests with different balloon sizes and tensions, and even coated the inside of the balloon with oil, in an attempt to reduce the spray, with no real change in the results.

But an even more serious problem is that unless the balloon is under a significant amount of tension, it will either not puncture at all, or the puncture will not propagate! If this happens in flight, we will experience a total menticulation failure and the entire experiment will be ruined.

So it was back to the drawing board (I have an ACME drawing board, the same brand Wile E. Coyote uses). I had to come up with a method of simply and smoothly deploying the soda. When I'm faced with a problem like this, I like to sit in the workshop and idly play with the various parts and tools that I have available. What I'm looking for is relationships between things that will spark a connection. After a while, this idea came to me.

The initial idea was to use a balloon inside the soda bottle to force the soda out of the bottle and up a tube into the apparatus. I already had the tube -- the Geysertube that Steve Spangler sent to me earlier in the year. I drilled out a hole in it so I could insert some plastic tubing, inserted a bit of copper tubing into the end of the tubing to stiffen it, ziptied a balloon onto the end, and stuck the other end into a hiking bota-bag, which acts as the bellows. A little hot-glue and tape sealed everything up.

Squeeze the bag, the balloon inflates, and liquid is forced up the tube in a reasonably controlled manner (this test had a leak, thus the bubbles).

Okay, so now I've got a basic method of deploying the soda sphere. The next thing to work on is, once I have the sphere deployed, how do I test the convection hypothesis in a manner that leaves no room for doubt about the results, and is as simple and foolproof (always a plus when I'm involved) as possible.

I'm also looking for a more precise method of pumping up the balloon than the bota bag (which was just the cheapest thing I could find that would work reasonably well). Something like a really, really big industrial syringe (500-1000ml!) would be perfect, but I haven't been able to find one yet -- if you know of something that might work, in particular something that's effectively self-locking, so after I get the bubble to the right size, I can just let go and the balloon will stay its current size, let me know!

Subsequent to these experiments, the blog got slashdotted, and I started getting lots of suggestions. One that I'm definitely going to follow up on in the near future is a modification of Ger's suggestion about a box of cola; my current thinking is to build a thin enclosure that will confine the convective flow pretty much to two dimensions.

Saturday, August 30, 2008

Comments on your Comments and Suggestions

Updated: Tuesday, September 2, 7am ET

First of all, I'd like to thank everyone who commented on the video (the original posting is just below this one) and made suggestions for how to improve the experiment.  I will try to address as many of the issues you raised in this posting, and amend it as I get more suggestions.  I'll also be posting about some tests I've already done and how they've evolved the design in a day or so.

James raises some objections about using balloons as deployment devices and suggests some sort of hard container (as do several other people).  Tests I've done indicate there are indeed multiple failure modes with balloons that make them problematic as deployment devices.  The big problem with hard containers is getting the fluid out of the container in microgravity; you can't pour stuff, and surface tension and hydrophilic/phobic effects are going to dominate, so getting the liquid to go where you want it is going to be a complex issue.  Given that you only get one or two shots during a flight to get it right, and you're under significant time pressure, I want to keep things as simple as possible.

Why don't I just pop a mento into a cola bottle? If you look back through the older posts, you can see that this was my original idea.  During the last week before the flight, I simplified the experiment after realizing that if convection was an important factor, nothing much would happen, and it would be hard to see what was going on inside the bottle.  In retrospect, doing it this way would have demonstrated a difference between the two environments better than what I eventually did, but it wouldn't have shown what was going on.

Using a baggie of cola: this might actually work, but it might make it hard to see what is going on.  A variant that uses a flat "slab" of cola in a specially constructed container might work (Ger later suggests a similar idea), but there are several problems that would have to be worked out; getting the cola into the container from the bottle without loosing too much carbonation, and isolating/releasing/moving the mento in zero G.  If those could be dealt with, then it might be a very interesting experiment, in particular if some glitter was added to the cola so the convective flow is more clear. It might work better with a clear diet soda, like Diet Sprite, or perhaps Diet Club Soda. This approach had not occurred to me, and the more I think about it, the more I am coming to like it.

This may well be the way to conclusively demonstrate the difference in convection, because it could also be performed with the same apparatus on the ground. However, it won't look as visually cool as a doing something with a sphere of cola.

Precision measurements: I don't know this if will be feasible given the constraints we have to work under, and our uncertain ability to precisely control the environment.  For this reason, we need something that demonstrates a really clear difference between 1G and 0G.

Cperdue suggests an ingenious deployment method (and Nick later provides a variant).  The main problem with it is that it would have to be scaled down; the biggest cola bottle we're going to have onboard is 10 or 12oz.  Also, the TSA might get a little bit concerned about allowing long pointed sticks aboard.  Finally, there's the issue of clearly seeing what's going on.

Matt suggests chemically popping the balloon.  If popping the balloon were the only issue, this might be interesting to investigate.  There's also the issue of whether Space Adventures will allow a chemical that dissolves rubber onboard.

Rustin suggests I use "aircraft" instead of "plane" in my description of some of the physics of Zero G.  Yeah, I could, but plainly I was trying for an extended play on words.  I did use typography to differentiate the two usages.

An anonymous coward takes issue with my use of "weightless" and "oG".  I didn't use the former term at all, and my opinion of his other quibbling is identical to Winston Churchill's opinion of objections to prepositions at the end of sentences: it is arrant pedantry up with which I will not put. Learn something about frames of reference, go find a lagrange point relative to the entire universe, then come back and argue with me.

Using IR controls: I have come to agree with the very next poster, who contends that servos are overkill.  I am going to take my own advice and keep everything as simple as possible.  Less failure modes that way.

"As long as your ball of soda is floating without hitting anything..." This is easier said than done. Given that most of the passengers on a flight are Zero G virgins, the inside of the main cabin resembles a 3D peopleball machine in multiball frenzy mode.  When someone's paying $5K+ for a ticket to ride (apparently the price just went up), they probably will be a wee bit upset if they get hit in the face by an errant cokeroid.  This is why we did our experiment in the seat section, which is empty during the parabolic segments.  That area has significantly less airspace (so to speak), and any incompletely collected soda is going to splatter somewhere.  This is why all the experiments have to be done in a sealed environment.

The Zero G coaches do release some small bottled-water balls in the main cabin, but these don't cause a lot of mess, and getting rained on is considered part of the fun.

The complex idea suggested by the anonymous non-coward about using a spherical cage that squirts cola into its center would probably not work well.  The cola would have to be precisely synchronized, and its momentum has to go somewhere, so I think the mixing would be turbulent enough for drops to be ejected.  However, I like the general structure of the device, and will keep it in mind the next time I build a device to punch a hole in the space-time continuum.

Richard mentions that the Mythbusters found that removing the coke from the bottle affects the reaction.  My thinking is that the shape of the bottle helps with the convective flow, which was what we were investigating, with limited success, in our original test.  Also, pouring the coke out of the bottle obviously causes some of the CO2 to be released, so a device that does not require the soda to be poured into an intermediate container would be preferable.
Valisk kvetches about my coining of the word menticulation.  I believe that it is an entirely cromulent word, and that its widespread use will embiggen the English language.
Coating the mento with something the coke dissolves: the problem with this is timing.  Keep in mind that you're only in 0g half of the time during the parabolic segment, and for 20-25 seconds at a time.

Alka-seltzer tablet in water: Toby suggested this, and he's not the first; one of the coaches on the flight told me he's always wanted to do this one. However, the situations are not equivalent, because the CO2 is generated by a chemical reaction in alka-seltzer, as opposed to a physical one in DC&M. So as long as water can reach the tablet, the reaction can continue.

The video Toby linked to is just too cool not to embed, so enjoy!

Thursday, August 28, 2008

Menticulation of Diet Coke in Microgravity!

Note: since the appearance of the slashdot story, lots of people are commenting and making suggestions.  Thanks!  I'll reply to them as a group in a day or so.

As I've mention in several prior postings in the blog, the big experiment we wanted to do during the flight was seeing how the Diet Coke & Mentos reaction works in microgravity. If you haven't read those posts, please do so to get an idea of how the experimental apparatus and goals evolved over several weeks. You may also want to check out my Youtube videos for other high-speed videos I've done, including one that shows the reaction at 1200fps on the ground.

Before I go any further, I want to thank everyone at ZeroG and Space Adventures that went the extra mile to make this experiment possible, in particular the science liason, Michelle Peters. And I'd also like to thank the TSA screeners, who arrived on site already totally up to speed on what we wanted to do (they'd even seen my test videos). Whatever you may think about the rules that the TSA enforces (and I agree with Bruce Schneier in that regard), the fact of the matter is that the frontline staff that you deal with have little or no freedom to apply common-sense discretion, and are often placed in situations where they don't have the time, or the background knowledge, to make an informed decision, which means that the default answer is "no". When you couple that with the fact that anyone can be having a horrible day, and some small percentage of people are jerks to begin with (a smaller percentage than most people assume), and multiply by hundreds of thousands of people going through security a day, it's a recipe for horror stories.

But in our case, since the screeners had been pre-briefed, it was easy to demonstrate that everything we wanted to use was well within the TSA rules. The only thing that didn't fly was a tiny ball of modelling clay that we were going to use to mount the mento onto a ziptie with, and the screeners helped brainstorm an acceptable (and better!) mounting method.

As described in a previous post, the hypothesis that we wanted to test was that convection of the soda was an important part of the whole reaction; under normal gravity, bubbles formed around the mentos rise up through the soda, allowing more soda to come in contact with the candy, and thus more bubbles form. However, in microgravity, there's no "up", so any bubbles that form will just stay near the mento, and will in fact keep new cola from reaching it.

So lets get right to the video, and then discuss what we learned.

I'll begin by discussing what went wrong.

Our first problem was that we weren't quite in free-fall, because in order to do the experiment, we had to be strapped into seats next to the emergency exit window (to get the light we needed). If you think about the geometry of the parabolic arcs from the perspective of the actual plane, the true zero-g path forms a parabolic plane, and (I'll try and state this as plainly as possible) the pilot attempts to fly a path that causes the (physical) plane to follow the (geometric) plane.

I say "attempts", because it's humanly impossible for a pilot to do this perfectly. So anything attached to the plane (as we were) is going to experience some small amount of residual gravity, not to mention the effects of any air turbulence.

Even if the pilot does this perfectly, only those parts of the (physical) plane that intersect the (geometric) plane will be in true free fall. Anything above or below that perfect plane (in the perfectly-flown plane!) will experience a slight amount of residual acceleration, because it's not free to orbit the earth in a free fall path, but is rather being dragged along either slightly faster or slower than it really wants to travel. In practice, of course, this tidal effect is tiny compared to the errors caused by the pilot as he or she attempts to fly the true parabolic path.

So because the experiment was attached to us, and we were strapped into the seats, and the seats were attached to the plane, the entire apparatus was subject to some residual accelerations. In order to eliminate them, the Mark II Menticulation apparatus will have to be free-floating, self-contained, and will have to operate without being touched. This will permit it to freely fall in a zero-g parabola independent of the path of the body of the plane (although there will be some residual effects due to things like air currents in the cabin, of course).

As a side-point, it's interesting to note that on these flights, from the standpoint of the passengers, the pilot doesn't need to fly an absolutely perfect parabola; as long as he or she can fly a path that is, on average, close to the perfect path, nobody inside the plane will really notice the difference.

The second problem we had was that we wanted to create a reasonably sized ball of soda, and then put the mento into it. However, the nozzle we used to control the soda flow was too small, and we couldn't control the exit velocity properly (and so we got all the squirts). On the second parabola (not in the video), we tried removing the nozzle, but we couldn't get a bubble of soda to detach from the bottle, and everything got messy - a blob of soda impacted right on the camera window, obscuring a lot of the view.

In order to fix this, we're going to have to come up with a method that deploys a preformed, properly positioned bubble of soda.

Finally, the video was slightly out of focus. We had to manually set the focus on the camera before doing the experiment, and it was difficult to keep the coke and mento at the correct distance, considering all the other things we were having to do.

Even with all these problems, I think we got some interesting video and results. It's not definitive, but it looks like the reaction is slowed down by the lack of gravity, and we also noticed something we weren't looking for; the cola apparently clings to the mento (likely, it's hydrophilic), resulting in the interesting dynamics when I moved the candy. A followup experiment might be to compare the behavior of some water surrounding a mento vs. a ball bearing.

The Mark II Menticulator - Initial Design

I've spent a few hours thinking about an improved experimental apparatus, and I think I've come up with something that, with a little refinement, will do the trick.

The experiment will be housed in a transparent case constructed of acrylic or lexan panels locked together by t-slotted structural framing. Inside will be a rubber balloon of soda trapped between two spoonlike holders, one above, and one below. A hobby r/c servo will be mounted inside the box, with two arms extending from it, such that if it rotates in one direction, a sharp tip will puncture the balloon, hopefully releasing the soda which will remain between the spoons; then when it rotates in the other direction, a mento will be moved to the center of the bubble of soda.

The servo will be directly controlled (no radios onboard!) by a small hobby microprocessor such as an Arduino. The microprocessor could also have some sensors to collect related telemetry (accelerometers and so forth).

Finally, several strips of high-intensity LEDs will provide the needed light for the Exilim EX-F1 camera.

Tuesday, August 26, 2008

What the Zero G experience is really like

The ZeroG website gives a broad overview of what you get for your $4K, but I thought I'd set down my impressions while they are fresh in my mind.

The whole process takes about 5-6 hours.  You arrive at the meeting place (in our case, an airport hotel) and check in, and you're given your flight-suit, a carry-bag, and a plastic nametag, which, according to long-standing astronaut tradition, is worn upside down if you haven't flown before.   You get introduced to your coach (ours was a former passenger who finagled a job for herself; James' reaction to this news was to inquire if summer jobs were available!), who is overly enthusiastic about what you're about to experience, etc., etc., etc.  It is at this point that you will start thinking they're laying it on a bit thick; in a few hours, you will change your mind.

Each coach handles a group of about 10 people; you get color-coded badges and socks that identify what group (blue, gold or grey) that you're in.

In our case, we also had a meeting with the TSA security team for final approval of our experiments.  They'd been completely briefed on what we wanted to do, so there were no real surprises.

Then you sit down for a light low-protein meal (it helps settle the stomach, and carbs soak up any acid overproduction) and watch a 35-minute video that goes through the details of the flight, safety precautions, and so on.  It's at this point that you take your motion-sickness meds if you've decided to use them; we did, though now that we've done it, in retrospect we probably didn't need to.  On our flight, one person got a little queasy, but only after the actual parabolic segments!

When that's all done, you go through TSA screening, get on a party bus (ours had a stripper pole!), and go out to the plane.

Once onboard (through the rear stairs), you get the usual safety briefing. Since the flight operates under the normal airline rules, it has to have a trained flight attendant aboard in addition to the coaches, flight director, and pilots (at least, we think there were some pilots aboard, we never saw them for some reason). While there was a cute comedy moment in the briefing, they need to add something to it along the lines of "in case of sudden loss of cabin gravity, a silly grin will appear on your face."

The seating area is at the rear of the plane, and the floating area is divided into 3 zones, one for each group.

The FAA clears a block of airspace for exclusive use by G-Force One (I still think it should be called G-Force Zero), and it takes about 30 minutes for the plane to get there. Then everyone moves to the floating area for a final briefing.

The floating area is heavily padded, but if you come out of a zero G segment upside down and near the roof, you might bang yourself up, which is why at the end of each segment there's a warning so you can get oriented. The transitions to and from freefall take several seconds so you have plenty of time to set yourself up; you'd really have to work at it to get hurt doing this.

There are no windows in the cabin except for the emergency exit windows; this apparently helps reduce the chances of motion sickness by removing external cues about your orientation. In addition to a photographer who literally floats around taking pictures of everyone, there are 6 HD cameras installed in the floating areas. Several weeks after the flight, you will get an edited video plus all the raw footage.

Each complete parabolic cycle is about 55% 1.8G and 45% 0G (the books have to balance, so to speak). During the 1.8G segments you are advised to lie on your back and stare at a point on the ceiling (another anti-motion-sickness trick). I tried other positions later in the flight with no ill-effects.

Each flight contains 15 parabolic segments, divided into 3 groups of 5. The freefall periods last around 25 seconds; they feel like they are much longer while you are doing them, and much shorter after it's all over. Between each group there are 3-5 minutes of normal flying while the airplane does a 180 to keep within the assigned airspace.  This turned out to be very handy, as during the last break, James and I went into the seated area and got set up for the Diet Coke & Mentos experiment, which we did using the light from the emergency exit porthole.  We did the experiment for two parabolas, then on the next one, we unbelted ourselves and swam back up the aisle and into the main cabin area, a very cool maneuver.

To ease you into things, the first parabola is at 1/3G (Martian gravity) and the next two are at 1/6G (Lunar gravity). You can do all sorts of goofy stuff like one-handed pushups, pushups to standing position, and the lunar "bunny hop" gait that the Apollo astronauts used to get around.

Then you go to full freefall. And I cannot emphasize this enough: in freefall, you do not feel like you are falling! For me this was by far the most surprising aspect of the experience.  I expected it to be like going over a hill on a roller-coaster, or like one of the "drop" rides (which I hate).  It was nothing like that at all!

I can be an eloquent bastard from time to time, but I am having real trouble describing what it feels like, because there simply are no words in any language to describe it. But anyway, here goes: it is not so much a sensation as it is the lack of a sensation, one you've felt all your life, one that is so much a part of your daily experience that you do not notice it. The closest you could come to it without actually going into freefall would be scuba diving, but there's a crucial difference. Even when you're neutrally buoyant underwater, if you focus really hard, you can still feel gravity tugging at your insides, pushing your organs against your muscles. In freefall, even that is gone. Once you experience it, you will know the answer to the famous Zen koan, "What is the sound of one hand clapping?" And you will literally be "enlightened".

During the first 7 freefall segments, there's various activities that typically get done; eating M&M's, playing with water spheres, etc. The last 5 segments are free-format playtime. If I have one regret about the flight, it was that I didn't spend one of those segments just floating in midair, eyes closed, doing nothing. I'll know better next time.

And that brings up a word of caution: you need to understand that this flight doesn't cost $4,000. It costs at least $8,000 -- because once is not enough. The first thing Natsumi said to me when we were sitting down, flying back to the airport, was "We have to do this again!" Yes!  My kind of woman!

After the parabolic flying is done, there's the 30 minute flight back to the airport.  As you descend down the stairs, your badge is ceremonially turned rightside-up by the flight director.  After some photos, it's back to the hotel for a light lunch and the distribution of flight certificates.  You get a nice totebag, and you get to keep your badge and flightsuit.

Which, of course, you'll need when you go on your next flight.

Sunday, August 24, 2008

3.. 2.. 1.. Ignition

We just got back from the ZeroG flight.  We managed to do 3 experiments onboard; the hard-drive gyro, karate, and Mentos&Diet Coke.

I will post later when I have looked at the video, but it looks like we got some cool high-speed video.

Everyone had a great time, and the most surprising thing was this - when you are in free-fall, you do not feel like you are falling.  You feel like you are floating.  It is a totally alien sensation.  Other participants noted this also; it is nothing like what you would expect from taking a drop ride at a theme park.  The general consensus was that the reason for this are the visual cues provided by the cabin, and the fact that you transition from 1.8G to 0G over a period of seconds.

Saturday, August 23, 2008

Practice makes Perfect

The rollercoaster ride that is the runup to the rollercoaster ride we want to take threw us for another loop when, the night before we planned to drive from Las Vegas to Los Angeles, we got a call that "G-Force One" (shouldn't it be G-Force Zero?) had a mechanical issue that needed repairing, and the Saturday flight was cancelled. There was, however, a chance that it could be rescheduled for Sunday.

After 24 hours of angst, we got the word that all was well and we could indeed fly on Sunday. So we are now skulking in a secret lair in Gendale CA (we were promised a stimulating hive of scum and villiany; so far, not so much), counting down the hours, and half-expecting that a massive earthquake will devastate Burbank Airport overnight.

In the meantime, we did several practice runs of the several experiments we are going to attempt. Here you can see James and I running through our core experiment, "Menticulation of Aspartame-sweetened Cola-flavored Carbonated Beverages in a Microgravity Environment".

After much thought, we have decided not to repeat the prior experiments that have been done in 1G, but instead do something that can only be done in ZeroG.

Prior research by Hyneman, Savage, et al. and others has demonstrated conclusively that menticulation is largely a physical reaction. The mentos, when introduced to the cola, provide a large number of nucleation sites because they are quite rough on the microscopic level, and thus permit the rapid growth of bubbles of carbon dioxide, which is in solution in the soda. In addition, the aspartame sweetener used in diet soda, as well as some other ingredients, reduce the surface tension of the liquid, making it easier for the bubbles to form.  The result is the pressurized shower of slightly minty soda that we all know and love.

However, there may be another important process that takes place during menticulation that has not been addressed by prior research -- convection. Consider than when the bubbles are formed, they will naturally rise to the top of the bottle (since they are less dense than the soda), and more importantly, this will draw more cola into contact with the mentos. But in ZeroG, there is no up and down, and so the bubbles have no inherent tendency to rise. So what will happen? Will the process continue, but at a slower rate? Or will the initial bubble formation effectively cut off the reaction entirely by isolating the mentos from the cola? Might we even end up with a thick skin of cola surrounding a bubble of CO2?

So it seems that the cola and mentos idea has gone from just being a cute stunt to being real science. If we get an interesting effect, we will be discovering something that nobody knew before, and adding, in a small way, to the sum of human knowledge.

In the above photo, you can see our experimental apparatus. We are using a plastic glove-bag to contain any spills, and have added an 8x10 acrylic window to it with heavy duct-tape. Taped to the window is a wide-angle rubber camera sunshade that we can screw the camera into.  Inside the bag are several ziplock sub-bags that will contain our materials. The cola is contained in a small plastic bottle with a nipple attachment that will allow me to dispense small amounts of soda in front of the camera port, at which point I will insert a mento into the cola using a ziptie with a small blob of artist's clay on the end.

Depending on how the first trial works, we'll try it again using a bigger blob of cola, and think of something on the spot to do.

On a side note, recent pictures I have seen of G-Force One indicate that the main cabin does have some windows.  If so, we should be able to get enough natural light to film at 300 frames per second!

Wednesday, August 20, 2008

Holy Ground

Subsequent to our interesting discoveries at Hoover Dam, we continued eastward on our scientific pilgrimage to check out other sites of interest.

First up was Meteor Crater, the best preserved impact crater on Earth...

The official story is that Meteor Crater is the result of the impact of a very small asteroid (approximately 50m across).  Of course, the official story is a total crock.  Meteor Crater was created in 1873 as a demonstration of the power of a super-weapon created by one of my personal heroes, the terribly misunderstood Dr. Miguelito Quixote Loveless.

Needless to say, that weapon, or a version of it, is what we found under Hoover Dam.

Monday, August 18, 2008

Pretty Dam Impressive

Since the Zero-G scheduling snafu has given us some extra days in the southeast, we're making lemonade by visiting important sites that might possibly be incorporated into our diabolical schemes. First up, Hoover Dam.

Now, you might think that the dam is just an incredibly impressive feat of engineering that provides tons of electricity and tames the wild Colorado river.  That's what they want you to think! However, a closer observation reveals the true purpose of the structure.

Consider this, which they claim to be one of the diversion tunnel spillways under the dam...

Oh, so innocent.  However, while #2 son distracted the tour guide, #1 son found the hidden control panel that activated the device's true function...

We have made a note that our plans for World Domination must not involve anything that gets within line of sight of Hoover Dam!

Saturday, August 16, 2008

Vegas, we have a problem...

We were literally waiting for the cabin doors to be closed on our flight to Vegas when we got a call from Zero-G with some bad news; this weekend's flight had been cancelled at the last minute.

Apparently, they'd done some modifications to the plane related to a NASA contract, but the needed FAA paperwork had not been completed in time, so they couldn't fly.

A seriously bummed Team Mad Overlord arrived in Las Vegas Thursday night, checked in (to room 321!) and went into bigtime logistical reconfiguration mode.  We finally determined that we could reshuffle work and school obligations sufficiently to permit us to extend our vacation through next weekend, allowing us to fly the next scheduled Zero-G flight in LA.  So we're going to run around the southwest visiting places like the Grand Canyon and Meteor Crater.

Meanwhile, we're doing Vegas'y things, like taking in the excellent Penn&Teller show and a little indoor skydiving...

In one of the great ironies of modern entertainment, Teller, the guy who never speaks onstage, actually has a much better voice than Penn -- probably because he never wears it out on stage...

Wednesday, August 13, 2008

Packing up and Heading out!

After much discussion with the folks at Zero-G, we're ready to head off and do some experiments!  The big news is that they've figured out a way to let us do Diet Coke & Mentos!!!  The solution turned out to be doing the experiment inside a portable glove-box.  This means we will be able to definitely answer the important question of "when the hero traps you outside your space fortress, can you rocket your way back to the airlock using only your favorite diet soda and minty candy?"

Above you see the complete experimental loadout.  The hard-disc gyroscope consists of a 7200 rpm drive unit that contains the platters from several dead hard drives.  The enclosure is a cheap USB enclosure that has the virtue of needing only a simple 12v power supply.  Testing showed that the best batteries to use were a set of 10 1.2v 2000mah NiMH cells; regular alkaline cells simply cannot source the required amperage, and even high-discharge lithium cells are borderline.

As a backup to the hard drive, we're also taking along a manual PowerBall gyroscopic hand exerciser.  Attached to the red pull-cord of the PowerBall are a 0.500" spherical rare-earth magnet and a matching ball-bearing.  These will be used both for pendulum experiments at 1/3 and 1/6G, as well as perhaps some ZeroG sillyness, using a blowtube (not in picture) to fire one past the other.  Both have one hemisphere painted red to make their rotational motion more evident on video.

For the Diet-Coke and Mentos experiment, a series of tests, some of them spectacularly unsuccessful, have resulted in the development of a deployment system that should work in Zero-G.  After the Diet Coke is uncapped and the gas pressure is allowed to equalize, a plastic sheet from a ziplock bag is placed over the mouth of the bottle, and a Spangler Geyser Tube is screwed on.  The Mentos are then inserted into the tube, and the first one in has a thumbtack affixed to it with modelling clay. The restriction nozzle of the Geyser Tube having been previously removed, deployment is achieved using a short length of plastic water pipe to ram the Mentos into the Coke.

Here is a video of the final test of the deployment system, filmed at 300fps using the Exilim camera.

Finally, last but not least, I have packed 4 pairs of Peril Sensitive Sunglasses. We won't need them, of course, but the Zero-G staff might!

Friday, July 25, 2008

I have only one ball, but it's momentous!

As a fallback to the gyroscopic hard disc idea, several people have suggested I try using a PowerBall gyroscopic hand exerciser.  I got one of these little torture tools too see how it works.  Basically, it's a caged gyro that is free to rotate in two of the three axes; the proper hand motion pumps momentum into the ball and spins it up.

My initial idea was to spin up the ball and then restrict the gyro to one rotational axis to see if it would generate enough force to precess the operator (me).  Unfortunately, the ball requires constant energy input or it quickly slows down, and the time needed  to cage one axis (using a couple of threaded bolts) is enough for it to lose a good deal of its momentum.  So that idea is out.

However, the forces and motions involved are sufficiently interesting that it's probably worth taking it onto the flight and seeing what happens when you spin it up in freefall.  So it's going on the list of experiments I'm trying to get approved.

Friday, July 18, 2008

Mentos... in... Space!

Everyone loves the Diet Coke&Mentos demonstration.  But how would it work in Zero-G.

Obviously, a major consideration would be the mess factor.  The experiment would have to be self-contained so as not to splatter everything in the cabin.  Here's my idea:

Take a standard 16-oz bottle of Diet Coke (available after security!) and use a modified Spangler Geyser Tube with a clear plastic bag on the other end to catch the spray.  The release mechanism would use a magnet to hold the mentos in place, then a quick shake should start things going.

This would look particularly cool if there's enough light for high-speed photography.

Sunday, July 13, 2008

Attractive ideas

My slightly demented australian friend Nick Martin, builder of nasty robots (and fortunately for the world, relatively small ones), has given me two suggestions that appear promising:

1) Play with some of the rare-earth magnetic building toy sticks; their interactions as they approach each other should be visually interesting.  I also have some spherical rare-earth magnets lying around somewhere, but they are insanely strong, and if I recall correctly, the force between two of these little bastards is inverse 4th power -- but what about one of them along with a ball-bearing?  Is that going to approximate inverse-squared?  If so, they might orbit each other!

2) Fun with a plastic slinky.  Nick suggests stretching out the slinky, releasing one end, and then releasing the other just as the slinky approaches full compression.  The dynamics might be very interesting.

Saturday, July 12, 2008

Your Space-Fu is Not Good Enough! Now suffer the wrath of my Mutant Star Goat style!

As part of our plans for World Domination, both James and Alex have trained in the Martial Arts for many years (I should point out that this is simply so they can defend their dear old dad from those misguided fools who oppose us).

So it has occurred to us to see if some simple self-defense techniques work in free-fall, where you don't usually have leverage, except that which you can apply through the body of your opponent.  It would also be interesting to see what happens when you try and do some simple Kata.

We're working with the boys' Sensei (a 6th-dan) to develop some routines that (a) might actually work and (b) will not impinge upon the other passengers (who might, at least for a brief time, be annoyed if they are on the receiving end of a Vulcan Death Grip)

Revolutionary Demonstrations

Some of the most interesting demonstrations that you can do in ZeroG revolve around conservation of angular momentum.  If you've got a spinning mass, you can do all sorts of cool things.

The trick is to get a really good spinning mass on the airplane within the rules.

Fortunately, there is a really good angular momentum source within reach of just about everyone reading this entry -- the hard disc in your computer.

So the plan is simple: stick an old (preferably high-rpm) disc drive into a cheap USB enclosure, and replace the wall-wart with a 12v battery.

Planned demonstrations: conservation of angular momentum (turn on drive, it spins one way, operator spins the other) and gyroscopic precession (spin up before we hit zero-g, then tilt the drive enclosure)

As always, your suggestions for improvements and additional demonstrations are appreciated.

Liquids in Space

The ZeroG folks have told me that they are a bit leery of experiments with liquids, except those done by their staff, because of the mess factor.

However, I've been thinking about ways to deal with that, by coming up with a simple liquid deployment and recovery device.

Here's the idea: take a 3oz bottle (the max allowed by the TSA past the checkpoint), and stuff it full of sponge material, so that it extends a bit past the neck.  Then soak the sponge to capacity, and squeeze out about 10% of the liquid.  This should result in a device that can deploy small amounts of water and also recover it (squeeze until there is a film of water on the neck, touch to water globe, release pressure).

Of course, if water bottles are available after the checkpoint, one could use a larger bottle purchased on site.

Also, after seeing this video, I'm itching to figure out something interesting to do with non-newtonian fluids.  The downside here will be what happens when someone sees us dumping cornstarch into a water bottle inside a secure area...

Some good news: the Casio Exilim EX-F1 high-speed camera has been approved for flight.  Now the only question is whether there will be enough light to get high-speed footage.  Oh well, it can also do HD.

Thursday, July 10, 2008

The Entire Family is going Ballistic -- Literally!

So anyway, since the final stages of my plans for World Domination may (or may not) include deploying Orbital Mind Control Lasers, it occurred to me that I should get some free-fall training, if for no other reason than it's hard to convince people you're serious if you're busy barfing at the time (ie: "One... Trillion.. Bleeaaaaagggghhhh... uh, Dollars!")

Fortunately, there is a company called Space Adventures that runs zero-gravity parabolic flights at a price that's within the reach of even the most budget-minded Overlord -- and realistically, if you can't get your wife to cough up $4k for a project like this, you aren't worthy of ruling the World!

Of course, it wasn't that easy. As soon as I announced my intention to do this, She Who Must Be Obeyed declared that she wanted to do it as well. And, of course, our sons insisted that they be included, on the grounds that this would make for the coolest "What I did during my summer vacation" essays ever. My protests that the extra $12k would be better spent on health insurance for my minions fell on deaf ears.

So we're all going ballistic in August in Vegas.

However, being as how my love of science is second only to my love of conquest, I have insisted that James and Alex do some experiments during the flight.

This is where you come in.

Your mission (and don't even think of not accepting it): come up with science experiments that demonstrate some physical principle, or some interesting difference between a 1G and 0G environment, that can be done by my kids during the flight. There are, however, some restrictions that must be adhered to:
  • The experimental materials must be small, pocket-sized if at all possible.
  • The flight operates under FAA rules, and therefore, nothing may be carried onboard that cannot be carried on to a regular airline flight.  Here is the list of restrictions.
  • The experiment must not inconvenience or injury to the other passengers, or cause a mess.
  • Given that each weightless period is only about 20 seconds, the experiment has to be pretty quick.
Also, if at all possible, it should be an experiment that would look interesting when filmed at 300fps using my Casio Exilim EX-F1 camera, which has been the source of much fun for me recently. I am not sure at this point whether I'll be allowed to take the camera with me, or whether there will be sufficient light for high-speed photography, but it would certainly be cool if that works out.

Obviously, these constraints make the obvious experiments we immediately thought of, such as popping a water balloon (it's been done, and it's messy, though as you can see in this video, you can mitigate the mess using a garbage bag), and seeing whether or not a yo-yo works in microgravity (might hurt someone).  Interestingly, there may be a loophole regarding electric screwdrivers; drills are not permitted, but an electric screwdriver 7" or less in length might be OK, which would permit some conservation of angular momentum demonstrations.

That said, we have come up with a couple of interesting ideas, which I will disclose in a subsequent proclamation. In the meantime, to encourage you to come up with other ideas, I will grant minor positions in the New World Order (something like, for example, Viscount of Fayetteville) to anyone who comes up with an idea we end up using.

You, for one, should welcome your new Overlord

My name is Robert Woodhead, and back in the dark ages, I co-wrote the first four installments of the Wizardry RPG game series on Apple II, PC, and Macintosh with Andrew Greenberg. As a joke, we put ourselves into the game, I as "Trebor the Mad Overlord", and he as "Werdna the Evil Wizard". Some may claim that declaring that I was insane was perhaps not the smartest of moves, but I would venture to point out that the goal of the game was to kill Werdna.

In any case, this got me thinking, and it occurred to me that the whole World Domination thing could actually be fun to do, as long as it was done for benevolent reasons, and as long as one took pains to avoid the classic mistakes. So, when I haven't been doing weird things with computers, helping people promote their websites, importing Anime and other Japanese films, and fighting robots, I've been devoting myself to this noble goal.

Of course, it should be obvious that this is all in good fun, and I don't really intend to take over the world.

Or perhaps, that's what I want you to think....