Sunday, May 31, 2009

ARML update

Sorry for the late update... I only got 3 hours of sleep last night.

ARML was absolutely awesome. I was on the CT A Team this year and we did pretty good. We scored 43 out of 50 on the Power Question (All 15 members of the team work for 1 hour on different facets of a difficult problem with only pencil and paper), which is right up there with the best teams. We placed 23 out of 44 teams in the A division, better than usual. (results) The B1 and B2 teams, which are still part of the CT team but are competing against other teams in the lowerr division (same problem set, though), didn't do as well, but still admirably. They were 52 and 75 of 86 in the B division , respectively.

We also got into the entertaining hijinks - stuff like staying up till 3 am playing Set, Bughouse, and Killer Bunnies; eating at the sketchiest chinese place in town and playing laser tag at the sketchiest laser tag place in the country; running en masse across 2 streets and half the campus in a 500-person crowd to get to lunch; climbing onto the roofs of covered walkways, and more.

Fun and geekery was had by all.

In other news:
Currently reading: D. B. Cooper by Elwood Reid
Read already this weekend: The Hunt for Red October by Tom Clancy; USS Seawolf by Patrick Robinson; and The Yard: Building a Destroyer at the Bath Iron Works by Michael S. Sanders.
Laughing at: Saturday Morning Breakfast Cartoons

Thursday, May 28, 2009


Unfortunately, I'll be taking a short hiatus from blogging from Friday morning through Sunday. I don't like to go three days without blogging, but I've got no choice - I'll be at ARML, a regional high school mathematics conpetition. It's three days of hanging out with 45 of the smartest kids from my state plus about 400 others, having fun, and occasionally doing math. I went last year, but that was about a week before I started blogging.
I'll be at Penn State for the region of the competition - the other sites are the University of Georgia, Iowa State, and UNLV. Penn State is a nice enough campus (OSU is so much better though), but there's not much there with all the students gone home, and State College, the attached town, is very small and doesn't have much more than one burrito place.
The highlights of the trip include the actual math competition itself, the team dinner of Saturday night, and late-night card games - particularly a card game I know as Presidency that appears to be a variation of Dai Hin Min and its American variation Asshole

Outside links: Wikipedia article and Official ARML site

This post is time-delayed until midnight so it'll stay on top of any other posts I do tonight.

See you Sunday!

Machnum Force almost complete

I made some more progress on it today. This morning, I put the second or third fillets on the third fin, so all three are attached perfecty.

I found a shock cord - 2 feet of 1/4" elastic. Hopefully it'll survive the ejection charge.

This afternoon, I drew 'MACHNUM FORCE' in block letters down the side of the rocket. then colored 'MACH' in blue and 'NUM FORCE' in black. The lettering smudged a bit afterwards, but it still looks pretty snazzy.

Finally, I've applied 3 layers of wood glue to the entire body tube as a smooth finish. It's a bit bumpy and imperfect, but I think sanding it with early-smooth sandpaper will clean it up a lot. With the entire rocket - nose cone, body tube, and fins - covered by 3 layers of wood glue, it'll be practically indestructable.

After the sanding, the only thing left to do is to attach the shock cord with an Estes-style mount, then wood glue over it for protection from the ejection charge.

Even with lots of protection for the shock cord, streamer, and nose cone (yet more wood glue on the underside of the shoulder). the recovery system will still take a beating from the G-size ejection charge exploding in just 6" free space of 29mm tubing. If I get a loadable motor - G77, G78, or G79 - then I might only put in half or a third of the ejection charge. Since it's still enough to deploy the system and it's not modifying the propellant, I think it's perfectly legal under the safety code.

This is my last post till Sunday except for the automated one in a few minutes. See you then.

Karl E. Baumann signature motors

Aerotech, in its 2009-2010 catalog, introduced a few new long burn motors, mostly Warp-Nine endburners. Three are 'Karl E. Baumann signature motors'. Baumann is Aerotech's director of operations and a L3 certified flier since 1995.

The line will consist mostly of long-burn motors and high-impulse motors. The first three out are all long burn motors.

The I49N-P is an endburner for the 38/360 case. It's a 19.7% I at 383 Ns, averaging 49.4N thrust with a peak at 64N. Its propellant mass is 190.8g.

The I59WN-P is a truly rare bird. It's the first 'Boost-Sustain' motor and apparently the first commercial composite motor to use two different propellants. It combines a coreburning White Lightning grain for a fast boost with an endburning Warp Nine grain for a burn time of 7.99 seconds. The 'boost' is about 170N, then down to about 60N dropping to 35N for the 'sustain' phase. It's a 486 Ns (51.9%) I load for the 38/480 case with an overall average thrust of 61N, a peak thrust of 173N, and 251.7g of propellant.

Both I loads require the 38EBFCPT extended plugged forward closure. Warp Nine is a fast-burning propellant and requires a high chamber pressure for endburning, thus there can be no space for a delay or even the regular plugged closure. However, the new closure will work with the Electronic forward closure; it also includes a threaded 5/16-18 hardpoint for attaching recovery systems, if you choose to go for a configuration with one or more chtues between the motor and E-bay.

Both are certified retroactively to last Friday, the 22nd.

I personally think the idea of combining multiple propellant is very cool and holds a lot of promise. How about Warp Nine and Blue Thunder motors with a bit of Black Jack or White Lightning for better visibility, or mixing Mojave Green with Redline for a very cool color show....

The L339N-P is a Warp-Nine endburner for the 98/2560 hardware. At 2793Ns it's a 9.1% I; note that it's larger than the listed maximum for the casing but Warp-Nine has very high impulse for its size. This'll help the motor fit into smaller rockets for better performance. It's got a burn time of 8.82 seconds and a maximum of 445N. It doesn't include a smoke charge like other 75mm and 98mm reloads, so you need a bulkhead plug installed in the standard closure.

Other KEB motors coming soon include very-high-specific impulse motor used modified Blue Thunder propellant, likely the same blend as the new F32T. In an interview, Gary Rosenfield said that test motors had produced specific impulses on 254 seconds, beating even the 225 of the F32.

New KEB motors will be introduced at LDRS-28 in July and 'in the near future'.

Full story here on Rocketry Online.

Wednesday, May 27, 2009

Program Progress

I'm still making progress on my simulation program. It's over 8 kilobytes now, but the simulation is fixed (previously the correction for changing the motor between simulations introduced a bad weight), a correction for gravity values at different latitudes, over 50 motors from MMX to G inputed, and more. I've still got a long way to go, but I've also got a 7-hour bus ride coming on Friday...

Tuesday, May 26, 2009

Master Motor List Update

I'm up to 223 motors, at the Cesaroni I247.

The F32 is included, but the larger reloads released this spring and such aren't. I'll add them next January when the next list comes out in Sport Rocketry.

It's one of my projects to finish this summer.

Kosdon is back!

Apparently, with the ending of the BAFTE rules on APCP, TRA and TRA Motor Testing (TMT) have reinstated Frank Kosdon as a motor producer. He's back with his loud, smoky, and aggressive reloads in 24, 29, 38, 54, 64 (!), and 75mm diameters.

The 24mm offerings include 35, 105, 200, 250, and 310 Newton-second casings ranging from 4.57" to 19.25" long, including E40, G120, H200, H240, H365, and H470 motors. (Note to self... 64 bucks for a casing and 30 for the motor might be a lot, but that's ingredients for a rocking 24mm Machbuster with a 295Ns H470 motor.)

29mm offerings range from G40 to I560; 38mm from I145 to J530; 54mm from I120 to L3000; 64mm from J330 to M3700, and 75mm from J180 to M5100.

There's also a 16000Ns 98mm casing, but no motors listed.

Story from Dick here and Rocketry Planet here.

Performance hobbies webstore with hardware and reloads.

And our historic feature: a 1961 The Tech from MIT featuring, on page 10, a story about Kosdon of MIT and Ronald H. Winston of Harvard developing a Isocynate rocket propellant for small motors. Winston is mentioned here as being appointed a Reagan commission on science, and possibly here as the inventor of a toothbrush sterilizer.

Monday, May 25, 2009

Opinions needed

I'm planning to go for my High Power certification at NERRF on August 14th, with a backup date of the 16th in case it rains. I've got the rocket, a Madcow Mozzie, and the reload hardware, a Doctor Rockets 29/180 system. However, I need both advice and help.

First, the rocket itself. It's a very high quality kit, and it's built more like a normal high-power rocket than a model rocket or even a mid-power rocket. It's got thick-walled body and motor tubes, thick kevlar shock cord, and a big, heavy screweye set solidly into the nose cone. It's survived two flights, including a complete parachute failure with no damage. However, after that crash, I'm worried about possible internal damage to the fin joints, and they're just 1/8" thick (good-quality 5-ply, though) and extend over 7 inches from the trailing part of the glue joint to the tip, although only about 5" from the body. I think they should be able to survive 450 mph without damage, but I'd like to hear your opinions. (At least 2 of my readers are / were certified, so I know you're out there)

Second, the stability. The Mozzie is a short, fat rocket - stability hell. It's got the huge swept fins, which really help, but I'm still a bit worried. The 29/180 motor is very long, almost 8" including the forward closure, and almost half of it is actually forward of the CP. The chute and protector and screweye add some weight, so I think I'll be fine. I'll run a CP sim just to be sure. Also, it's been exceptionably stable, even overstable, on D12s at under 50 mph, and it'll be going almost twice that by the time it even clears the rod on an H128W-M. A bit of speed makes up for sub-caliber stability. (I apologize for that awful pun).

Update: CATO, the rocketry club I belong to, has a new field that may be able to handle small HPR motors just half an hour from where I live. This would save me a trip to New York and such.

Gluing the Fins

The Machnum Force is finally getting its fins glued on. I was nervous for two weeks about doing the glue joint, but It's surprisingly easy - the big, heavy fins fit well in my Kuhn fin jig* and the wood glue dries very quickly in this warm but not humid weather. I attached the first fin with a single layer of wood glue, then put 3 layers of fillets on. The second fin is currently drying with its first fillets. I expect to be done with all the fins and fillets by Wednesday.

Next I'll do the name with Sharpie on the body tube, then apply one or two coats of wood gue over the entire body tube - not very thick, but just enough to make the entire rocket a single hard sheet of hardened resin able to survive anything.

First flight will be on a G78, G79, or G80 at NERRF on the 14th of August. Estimated altitude between 2500 and 4000 feet, speed between Mach 1.3 and Mach 1.5.

*Kuhn Fin Jig: a piece of angle iron, etc with a slot for holding a fin in place. See Handbook of Model Rocketry, Ch. 3 (7th edition: p. 30 fig.3-13).

My Mini Biological Experiment

Biology is normally not my forte, but ironically my longest-running experiment is biological. I've got a couple of old film cannisters, 2 clear and one black. One clear one has been filled with water for over 2 years, the other for a year, and the black one for a month. Starting with just water and whatever was in the 5mL of air, all three have formed small bacteria colonies. One of the clear ones has a whitish colony the size of a pencil eraser that once was green, the other has an orange colony that has faded somewhat recently, and the black one has a small whitish colony.

The Amazing One-Sided Magnets!

I've got two different magnets that have incredibly unusual properties. Both have one very magnetic face and one face that's almost entirely amagnetic. Their magnetic faces also have a rather strong magnetism for such small iron ceramic magnets.

Why? It appears they're Halbach arrays, a special arrangment of magnets that allows the magnetic field to reinforce itself on one side and cancel itself out on the other. They can produce one-sided magnets, cylinders with magnetic fields only on the inside, and other strange stuff.

Applications include fridge magnets that only stick one way, maglevs, 'wiggler' magnets for particle acclerators, brushless motors, magnetic couplers, and more.

Another good site.

Chat with God!

God is online now, communicating with us mortals through a cryptic flash interface that fails the Turing test.

My favorite interchange:

Human: yes.
God: Blimey.
Human: you're you're British now too?
God: Oh. I will tell my botmaster you said I am I am British.
Human: Why?
God: Reductionism.
Human: What's reductionism?
God: Reductionism is the philosophy that all psychology reduces to biology, all biology to chemistry, chemistry to physics, and finally physics to mathematical logic. Therefore, according to reductionism, I can understand you by means of logic alone without having a human brain.

Obviously God reads xkcd.

Saturday, May 23, 2009

Wolfram|Alpha Search Engine

WolframAlpha is a new search engine, and indeed a new type of search engine. Instead of searching sites, in searches information, so it's good for mathematical work, physics stuff, finding lengths of time, and such. It's got info on all sorts of stuff, like movies, chemicals, and musical scales and chords. I'm still learning how to use it, but it looks very useful.

Thanks to my aunt, Sarah Rambacher, for the pointer to it.

Can I make it?

I'm only at 336 posts, including this one, and I've got just 17 days to make my goal of 365 posts in the first year. That's 29 posts in 17 days, or about 1.7 posts per day. That's a rate of 54 per month, which so far I've only achieved in January do to a flurry of building and launching rockets. (The only rocket I've been working on in May is the Machnum force, and I haven't launched since April).

Fortunately, I've got a couple of factors working in my favor. I've got my computer back and working smoothly - Norton and Office are happy, IE8 isn't too bad (not very different from IE7, acts a bit more like Chrome, windows linked from each other are colored the same), and I have Nethack entirely self-contained on my backed-up documents (hurray for flash drives). This means I have access to the internet 24 hours a day, without having to use my parent's desktop or risk them looking over my shoulder, so posts will come at all hours now, not just late at night.

I've also got more material coming: the Machnum force being built, plans to launch more soon, my simulation program, music reviews, and more. With tennis over and summer coming, I've got a lot more time for building stuff, launching rockets, and blogging. I think I can make 365 by June 10th, and more interesting stuff is yet to come.

A few notes: I've averaging about 8-10 visitors per day, and for the amateur geek and amateur geek, both in and out of quotes, I'm #1 on google results. I show up on a few other reulsts, including my name, oddrocs, micromaxx staging, oop Estes rockets, Astron Invader, and a handful of others.

On the 10th, the Amateur Geek's first anniversary, I plan to do a bit of a retrospective.

Quick updates

Tennis: over

Cars of tennis coach, and two players on the girls team: pimped with Saran wrap and window paint and paintballs

Listening: More than you think you are by Matchbox Twenty

Me: becoming quite the little indie rock snob

Laptop: waiting for dad to install Norton

Jazz band: still rocking the free world, plus everywhere in the high school.

Savage Chickens: awesome

Latest graph paper doodles: cellular automatons

mandachan: done with softball season

me: tried. hungry. see you later.

Edit: spelling: fixed

Friday, May 22, 2009

Rockets in Cyberspace and Meatspace

Cyberspace: I've got my rocket simulation program on my calculator back up past 90% functionality. The main simulation is up and required only one quick bug fix (accidentally using diameter instead of radius while calculating drag), and since it's completely rewritten, it's almost twice as fast as the old loop. Variables are handled faster, less time-consuming 'store to variables' are used, and instead of a clunky loading bar, it displays the real-time calculations of altitude and velocity. Useful for long calculations (low gravity, no drag, large motors) so I have some idea of how long it'll take.
I've got MMX-D motors up, plus the E6, G80, and J570 for test purposes. The only part of the old program that I haven't re-added, besides the motor files I haven't put in yet, is the handling for staging rockets. The motor data subroutine displays propellant type, size / reload casing, and available delays for all motor in th program grouped by size, plus the ability to display initial weight, propellant mass, average thrust, maximum thrust, burn time, total impulse, and thrust curves for all 80-odd motors. (All Estes, Apogee, and Quest motors minus the D5, all 18mm-29mm AT SU motors, and 18mm, 24mm (non-RC), and most 29mm reloads, plus a smattering of larger motors: I435, J570, K550, L1420, M1939, N2000).
I also completely rewrote the descent calculator today. I calculated the relative areas for circular, square (side and diagonal), hex (side-to-side and diagonal), and x-form chutes. I also derived the equations for descent rate in terms of weight, air density, chute drag coefficient, and chute area, and the program can now derive the descent rate from chute size, or vice versa, with all the other parameters the same. The calculations were fairly simple: just set weight (9.8N per kg) equal to drag (0.5pCDV2A) and solve for whatever variable you want. (p (rho) is the air density (1.2062 at sea level); CD is the drag coefficient of the chute (between 0.75 and 1 for parasheets (can lay out flat) and about 1.5 for parachutes (actual half-spheres)).

If you want the code, just drop me a line and I'll send a text file, or maybe an actual file to download to your calculator once I get TiConnect on my laptop.

Meatspace: I started gluing the first fin on the Machnum force tonight. I'll use one layer of wood glue to attach each fin (12+hr drying time) and 2 to 3 per fillet (24+hr drying). This is the last truly tricky step (before came cutting and wood-glue-smoothing-and-strengthening the fins), and from here on out it should be pretty easy. I hope to fly it at NERRF in August along with the Mozzie which'll be my cert flight.

Thursday, May 21, 2009

The King of Grunt

According to Aerotech Catalogs, the 9-grain J570W relaod for the 38/1080 casing is the 'King of Grunt'. And indeed it is. The single most powerful 38mm motor available, it packs 1060 Ns into 18" of metal tubing and releases it in just over 2 seconds. It peaks at 2000N of thrust and can lift a 20-pound rocket.

And that's just from the earth. Operating in the 1/6th gravity and no-drag conditions of the moon, in which APCP can still burn, it can throw a 4-ounce rocket up to 545,922m (that's 545.9km, or 1792807 ft, or 339.55 miles). It'll reach 1307m/s (4292fps or 2926 mph), which is 81% of lunar orbital speed.* In case you're wondering, the optimum delay is 832.7s, or just under 14 minutes. I haven't tried it with larger motors yet, but I suspect a K motor (or a J with an upper stage) could reach orbital speed, and that simple, fairly cheap 98mm M and N motors could easily loft 20 pounds into lunar orbit - at under 20 bucks a pound.

* I learned a nifty trick somewhere for approximating the mimimum low-orbital speed around any large body. Find the distance a body will drop in one second. For the moon, that's about 2'8", for earth it's about 16'. Then find the distance that you gotta travel in a straight line for the surface to fall away that much from under you. For the moon, it's just about a mile. For earth, it's 4.9 miles. Presto! In order to fall constantly and not hit the moon, you merely have to travel about 1 mile per second, or about 1600mps. For the earth, it's 4.9 miles per second, or about 17000 mph. Confusing, I know. I gotta reword it.

Also, since the moon has no atmosphere, you can have a very low lunar orbit - 6.5km is all you need as that'll take you above the highest point on the moon, which is on the far side and about a kilometer taller than Mons Huygens, which is usually listed as the highest point. On earth, you need to be up at least 100 miles or so to avoid atmospheric drag.

Tuesday, May 19, 2009

Computer Fixed

By brute force. The geek squad took a look, saw many problems, and with my permission wiped it. Fortunately, I had my data backed up to a flash drive. Then, they test it out... and it crashes again. Turns out the problem was a faulty 2GB strip of RAM. Now I'm down to 3GB (still plenty) and my computer is wiped, but I've got IE8 (looks the same as IE7), and a clean slate with no programs to cause problems.
I'll put Picasa, Itunes, Norton Antivirus, and a graphing program for physics on soon, and maybe Chrome, GEarth, or NetHack on later. (NH is a self-contained app in my documents, so all my scores and bones files are safe.)


Wisdom teeth starting
to intrude on my mouth now
very annoying

just a bit painful
but mostly just distracting
Stupid third molars

I identify
with teething babies now and
I only have three

End of haikus for
tonight because the resident
geek needs lots of sleep.

Tshirts, Want.

Questionable content is one of a few very epic webcomics I read. Jeph Jaques makes his living off the comic by selling shirts and stuff, and I want to get several of them:
Math is delicious!
Clearly I have made some bad decisions
Music+Science=Sexy! (That's me, folks.)

Not for me, but for a friend: this one

Available as a poster and shirt: the most useful guide to scientific history you'll ever find. Want.

Monday, May 18, 2009

Cool-sounding stuff

Ergosphere: The area around a black hole where energy can be extracted from it. A possible energy source in the distant future.

Cosmic Censorsship hypotheses: Naked singuralities - black holes without event horizons - cannot exist according to this theory. A well-done humorous name for a very real theory.

No hair theorem: all black holes have only 3 distinguishing characteristics: mass, angular momentum, and charge. All other information ('hair') disappears into the black hole along with light and matter.

Not to be confused with the Hairy ball theorem, which states that you can't comb the hair on a sphere flat without creating a cowlick, or two. It is obliquely referenced in the epically funny Surely you're joking, Mr. Feynman! in 'A different box of tools'.

Other news notes from my life:
1) I've discovered Coldplay and Viva la Vida. Interesting.
2) My laptop is in the hands of the Geek Squad.
3) I'm thinking of going for this.
4) Again, gotta go to bed. more tomorrow.

Sunday, May 17, 2009


1) My computer is heading off to geek squad tomorrow. There are any things wrong with it. I suspect it may be a faulty connection to the RAM because there are so many, varied problems.

2) I went and watched the new Star Trek movie today with my dad and Mandachan. I was very impressed with the movie. Setting it in an alternate universe through time travel allows some very entertaining senarios - like Kirk being a juvenile offender who steals his stepfathers' car (and accidentally drives it off a cliff) and starts bar fights. There were millions of in-jokes, but even non-Trekkie Mandachan was able to understand and like it.

3) Thanks to Dick for the shoutout yesterday.

4) more coming tomorrow. Must sleep now, though.

Saturday, May 16, 2009

Rocket Motors from the Old World

Looking for info on the original Aerotech G30 (anybody got anything), I happeend to stumble upon this: the best collection I've seen of data and pictures of British, Czech, and Spanish rocket motors.

Interesting stuff from Britain includes:

An 11.35Ns 'C5-3' with a 5-second burn that may or may not be the same as the Estes C5-3

A 29mm blackpowder D3-6

The infamous 40mm F36-5 Pitfield motors

F72-0 giant booster motors

A G156-0 'Guppy' that's as wide as it is long

An H150-5 blackpowder motor

Several primitive RMS / LMS motors, including a 76mm K1280

The Czech Motors, including what are known as the 'Delta' motors, were sold under the brand '19 decembar', which I presume is a date but the menaing is unclear.
They include the 'Delta', the 10.2mm x 34mm A2-7; a mini-size B3-3 that somehow originated in Wisconson, and a series of 18mm motors that included 55mm-long A7-3s, 60mm-long B6s with 3 and 5 second delays, C6-0/3/7s roughly equivalent to Estes motors, and C30s with 0, 3, and 7-second delays. They used a dense blackpowder mix which performs about 30% better than Estes motors, and a Potassium Chlorate / Coal / Formaldehyde resin delay that produced thick balck smoke, but also coated the interior of the model.

The Spanish blackpowder motors included a 21mm D, a 30mm G, and a 35mm H153.

The site also includes information on flare rockets and British military rockets - those of "the rockets' red glare" as noted by Francis Scott Key in 'The Star-Spangled Banner".

Friday, May 15, 2009

New Aerotech Catalog Out!

Having a very very very geeky moment. The 2009-2010 Aerotech Catalog was released today. It incorporates the new Mojave Green motors, plus the Warp-Nine endburning 'moonburners'.

One of the biggest and best changes I see, besides of course the new motors, is the color coding of the motor thrust curves. The old (2007-08) catalog that I have the hard copy of has all the curves in different bright colors, with no two motors on one graph having the same color. Visually interesting, but not particularly helpful. The new catalog has the different 'flavors' - W, T, R, G, J, FJ, N - matched to the colors of the curves.
From this I note several interesting things. The D6, E6, E7, F13, and G12 RC motors all have Blue Thunder propellant, normally a fast-burning propellant, but these are all low, flat curves, which I suspect are endburners. The same pattern is seen in the 54mm J180T.
No single motor casing has all 7 flavors available for it. The 29/40-120 has all but N; the 38/360 all but FJ and the 38/480 all but G (both have the fast and slow burns Ns, though).
Reline and Mojave Green have almost identical burn patterns.

here is a great chart of casing size versus propellant showing all but the most recent arrivals.

Now: the changes in motors, with many new arrivals and a few losses.
The D10W and F32T have joined the 24mm SU lineup.
The G78G has joined the 29mm SU and LMS lineup.
The I65PW, J125PW, and K1050PW LMS and J420R SU motors are gone, but the K250PW LMS has been joined by the I350PW SU.
The 24/60 RMS system with the F35W is new.
The 29/120 has a 9th motor available: the G76G.
The H250G is now available for the 29/240 hardware - I could fly it after I get the seal disk from Apogee.
The 38/260 adds the I49N and I245G; the 38/480 adds the I59WN; and the 38/720 adds the J500G.
The 54/852 J90W is not new, but tis thrust curve was absent from the old catalogs.
The 54/1706 adds the K805G; the 54/2560 adds the
K270W and the K1050W.

There are many new reloads for the 75mm and 98mm casings:
75/3840: L1390G
75/5120: L1170FJ, L2200G, M1500G
98/2560: L339N (25.4x greater impulse than the G339N with the same propellant, but the same average thrust.)
98/7680: M2100G
98/10240: M1800FJ
98/15360: N1000W, N3300R

For one-use motors, 4 were lost and four were gained, but the new motors are smaller, more interesting, and more useful motors than the old ones and include a 24mm F and a D prefect for smaller 18mm rockets. For reloads, 19 new reloads including a new casing are introduced without dropping any of the old line.

Well done, Aerotech. I look forward to trying some of your new motors soon, including the F32T (already owned), G78G (machbuster), and perhaps some of the Mojave Green reloads.

Awesome Picture

Phil Plait points at quite possibly the coolest picture ever: a picture of Atlantis and the Hubble Space Telescope crossing the disk of the sun. Two objects - the 35m shuttle and the 13m telescope - moving at 7km/s, captured through a 130mm Takahashi refractor - top of the line, but far smaller than the giant Schmidt-Cassegrians used for most deep-sky shots. Congratulations to Thierry Legault.

Thursday, May 14, 2009

Hacker Time

From Wikipedia's Even More Best of Bad Jokes and Other Deleted Nonsense:

Hacker standard time (HST) is a relative time zone occurring no less than three hours behind where the hacker actually lives. This means, should a hacker be awake at 3am according to local time, it is only midnight in his time zone. It is important to note that hacker standard time is adjustable according to occupation and time of year. Should the hacker still be in school, the three hour rule generally applies. However, during his summer vacation, the rule is traditionally scalable to at least an 8 hour difference. This enables hackers to miss daylight entirely, keeping to their necessary vampiristic existence.

If the hacker is out of school and in the working world, hacker standard time may be adjusted such that the hacker adjustment takes place only at night. This means should the hacker be awake at 2:59 am local time, it is but 11:59pm his time. However, when he wakes up at 7am for work, it is 7 am in both HST and local time, meaning the hacker simply scales back the amount of sleep he gets, existing on the half hacker standard time regimen.

So, when you see a hacker early in the morning (1pm or earlier in local time), please avoid loud noises. Allow them to adjust to their surroundings for at least an hour before any valuable information exchanges are conducted.

How true. I sleep 12-6 on weekdays and about 2am-noon on weekends.

Death Doom and Disaster!

Okay, it's not quite that bad.

Yesterday, during chem, I opened the periodic table app on my calculator to test for the teacher whether or not it included electron configurations. Somehow, it crashed, and none of the usual outs - delete, clear, on button, off, etc - would work. The auto-power-off didn't trigger, either. The only way out was to remove the batteries as suggested by the manual. This got it back into working order, but at the expense of clearing the RAM. The cost: my 9kb, 1000+ line, 3-months-of-work TIRASP-09 program was in the RAM, and it got completely wiped out.

Fortunately, there were a number of mtigating factors. Except for a few program variables, which will be recreated the next time I run the recreated version, it was the only thing in the RAM - all my other programs were in the protected archive, which was backed up by the secondary silver oxide battery. I knew TIRASP-93 very well, but I am not familiar with the code of most of the others, several of which were written by a friend, including a massive blackjack game which I had rearchived just minutes before.

I also had finished writing the complete data files for all 72 motors that I've compiled data for on a hard copy - graph paper - so all I need is half an hour for typing and I've got it all back. I also was very familiar with the code, and I've already rewritten - and improved - the basic flight simulation loop and half the thrust curve displaying code. The basic data architecture is better since I'm writing this from scratch instead of trying to improve the original, which went through half a dozen revisions of poorly-designed program flow. I expect to have 95% of the version 2.3 functionality up and running by Saturday and to have the planned revisions up to V3.3 by next week.

Wednesday, May 13, 2009

Monday, May 11, 2009

Eh. More randomness.

1) Congrats to Mandachan for a great game today. She went 1-for-2 in 4 AB and scored twice, reaching on a single, a walk, and an error. Too bad it wasn't a home game, though, so I could have watched...

2) Already I've made another modification to my simulation program: a simple subroutine that calculates and displays motor weight, propellant weight, burn time, average thrust, and total impulse in easily-readable form, using lowercase letters to display seconds and grams. Now I've just got to figure out how to encode available delays in the motor data files.

3) STS-125 is safely in orbit and headed towards Hubble. Prepare for 5 to 10 more years of mild-blowing images, incredible discoveries, and more.

4) Tennis match and Jazz band performance tomorrow, so chances are I won't have time to blog. Sorry.

Sunday, May 10, 2009

Randomness in the Middle of Busy

Meh. I've had too many tennis matches, too much insultingly easy homework, and too much work at work (ironic, no?) for much rocketry stuff, much less blogging, lately. A few updates, though:
1) I went to the Ledyard Drama production of Ovid's Metamorphoses on thursday and saturday, and they were amazing. I was very impressed. Congratulations to Dr. Zotos and the cast and crew.

2) The shuttle is set to lift off to repair Hubble at 2:01 pm tomorrow. 5 to 10 more years of delicious astronomical goodness await.

3) I've got my rocket simulation program down to nearly perfect. Under 8kb, text searching for all motor files, over 40 motors (from MMX to 29mm I200 including every Estes motor, 2 Quest, 2 Apogee, and most everything Aerotech has from D to H), an even faster main simulation loop, and extra goodies like provisons for simulating staging, thrust curve displays, motor data displays, and 2-way descent rate vs. chute size calculations with 5 chute shapes. And its continuing to get smaller, faster, and more advanced.

4) I've picked a recovery system for the Machnum Force: a 2" x 40" streamer originally from the Comanche-3. Light and small and cheap, and it'll bring it down fast but safely.

5) more tomorrow.

Sunday, May 3, 2009

I need advice

So I'm moving right along with the Machnum Force. I've got all three fins finished and very smooth and strong, and the nose sone now has about half an ounce of weighting plus a nice strong eyehook in it. Now, though, I'm not exactly sure what to do. I've enever built a rocket to stand up to 1000 mph forces before - Mach My Day was slower and smaller, and Mozzie has a much stronger design and is bigger and slower. Here I have a half-millimeter thick cardboard tube that's going to be subjected to incredible lateral forces, and less than half a square inch each to attach thich fins and will carve out a slot of 65 Liters of air per second.

Currently, for the fins, I plan to attach them with wood glue, put CA into the cracks, then do 2 or 3 layers of fillets. I think that properly done it should stand up to anything I can put this rocket through. is this a)overkill, b) okay, or c) I need epoxy and fiberglass to have any chance of hitting Mach?

For the body tube, I have 13" of thin-walled kraft paper 29mm tubing from Apogee. Will this alone be sufficient, or should I slather a layer of wood glue or two on top, or spend 150 bucks on an otherwise cheap rocket to get fiberglass?

Please, respond. I need all the advice I can get.

Late Nite Randomness

I might try to stay up all night depending on how I feel in an hour or so. If I do, then my goal is not a full all-nighter, but to make it to either 5 am (see the twilight) or 630 am (see the sunrise). If not, then I'll take an anithistamine (for allergies and sleeping better) and be up around 10.

I've got the first two fins fully polished for the Machnum Force. The third is cut and currently in the glue-dry-sand-repeat cycle. It'll take a while to decide exactly how to build it, figure out how to weight the nose (enough for stability but not too much to hit mach), especially to glue the fins (3 layers of fillets coming) and to paint and sand it for a perfect finish. Even a one-shot rocket (If it survives 1000 mph and I get it back, it'll sit on a shelf and only use Bs and smaller) deserves super-strong construction and a perfect finish.

I've been listening to The Christmas Attic by the Trans-Siberian Orchestra since 1230. It's pretty good christmas rock, a bit mopey for my taste, although The World That She Sees is awesome. Next in the lineup are Beethoven's Last Night (also TSO), Best of Mancini, Selections from Victory at Sea and other favorites, and maybe some classic rock and Modest Mouse later on if I do stay up till dawn.

Finally, one thing from my trip to Oregon last year: I found a pillar of rock 6 feet square. Pretty impressive considering it represents about 1/2738506070000th of the land area of the US. However, that pillar is special beacuse I remember taking a flying leap off the cliff overlooking the river at Robert W. Sawyer River Park to land on it - it was very exciting jumping a gap with a 15ft drop underneath. Here is the best view I can find. The cliff juts out twice in the middle of the frame; the left one is actually the pillar. Another view.

Also, the river bluff I climbed that same day turns out to be over 150 feet high according to an altitude widget I have on google maps.

It's currently 209 am and so far so good, but mancini is done already.

Saturday, May 2, 2009


Didn't launch any rocket or such a nice day, but I helped my folks with lots of yardwork. Physical exercise can be good sometimes.

First I pulled some bittersweet down from the trees behind my dad's dental office. Most of the strands came down easily from the big old oak, but one vine, no more than an inch thick, went 60 feet straight up to the canopy and I could not budge it. Made a nice swing, though.

My parents and I spent much of the afternoon moving bushes around. We removed 2 large, deer-eaten evergreen bushes and tossed them down a cliff (literally - there's a 15-foot rock cliff in my backyard), moved 3 holly bushes, laid mulch down, and I think they moved more azaleas after I went to get the mower.

I retrieved a metal hook stuck up in a tree in my yard since october with my string-and-ess-hook combination, and got a ladder, climbed into the big tree in front of my house, and cut off some dead branches - one 15 feet long.

Finally, I cut the lawn. That poor mower must want to kill itself, because in the space of five minutes it had its entire muffler fall off, had the differential fail (cutting power to one of the two drive wheels), and developed massive vibration in the handle combined with a semiperiodic misfire in the motor. I've never worked with gas-powered motors much, but even to me that missed beat is awful-sounding.

Machnum Force

My new 29mm machbuster is finally being built, and no I won't apologize for the pun. It uses a 13" length of standard 29mm tubing, which I'll reinforce with either wood glue or a paper wrap.

The nose cone is a 4.4" long balsa ogive that I bought at NARCON from BMS. I slathered 3 coats of wood glue on, letting dry in between, and it's now covered with a super-thin (maybe a half millimeter or less) coat of dried resin, clear and strong and smooth, and much easier to paint than plain balsa. Well worth the effort.

The fins are 1/8" ply, crappy but strong 3-ply stuff from an old non-flying heliocopter kit and a clementine box. The fins are fairly large, about 6.4" long and 1.8" wide in a trapezoid shape, with a long sweep on the leading edge and a slight forward sweep on the trailing edges. Two are fully cut and sanded; one is fully finished with 2 or 3 coats each of glue on the 2 sides and the edges; the other just needs its edges done.

I estimate around Mach 1.5 - 1800 fps / 1000 mph on a G78 or G80.

Friday, May 1, 2009

The N Prize

The N-Prize is a challenge to launch an impossibly small satellite into orbit on a ludicrously small budget, for a pitifully small cash prize.
(from The official site).

It's a lighthearted contest, but a serious rocketry challenge: to put a 9.99g to 19.99g sattelite in orbit, and track it for 9 orbits, for either under 999.99 pounds sterling (1118 Euros / $1482 US) for a single launch, or per flight for a reusable system.

From the page:

Where'd it begin? The Halfbakery.

Are they serious? Yes.

Surely it's impossible? Very nearly.

Thanks to the tipoff from Dick and the full story from R2K.