Monday, October 30, 2006

Launch Log 2006.10.29

The first launch of the day was Mighty Mouse. We went with a B6 so we could see how the winds were affecting the flights without going too high. I put the usual amount of wadding in, but the shrouds were burned and part of the chute was melted. The next flight was Pipes, also on a B6, and the same thing happened. Pipes had a great flight exept for burning another chute.
Isaac preparing to launchPipes firing up to lift offthe upper stage of Isaac's Renegade firing up

We flew the first flight of Isaac's Renegade - we were starting with just the upper stage and flying on an A8. I should have calculated the needs of the rocket better because the A8 only lifted the upper stage about 20 feet. The second flight, we tried with both stages using B6 (the lower stage was B6-0 and the upper stage was a B6-6). The lower stage boosted the Renegate to about 35 feet and then upper stage failed to ignite and we had a nice big lawn dart.
the definition of a rocket-turned-lawn-dartthe nose of the Renegade got a little dirtied

The lower stage of the Renegade is intended for a tumble recovery. I was busy watching the upper stage crash and I didn't see if the lower stage was tumbling nicely or not. We'll need to watch for that in the future - the more they tumble, the better.
Outlaw initial thrust just before lift-off

After the troubled launches, we flew the Pencil and Outlaw on C6 motors. The wind was starting to pick up, but we still had some great flights. The Outlaw carried Isaac's parachute man and deployed him near apogee. Finally, we flew Mighty Mouse (after putting on a new parachute). Parachute man was riding in Mighty Mouse, causing me to underpower it. The flight went fine and everything recovered okay, but we had used a B6-6 and the chute opened about 15 feet above the ground :)

Friday, October 27, 2006

Prompting in Bookmarklets

Jon Udell's Library Lookup project was my introduction to Bookmarklets. That was a year or so ago and I have used bookmarklets here and there, but I haven't needed to prompt for anything in the past. The good news is, that prompting for parameters in the bookmarklet is even easier than pulling data from within the current page.

The bookmarklet that I needed today was for looking up Perforce changelist details:

javascript:{var changelist=prompt('Enter Changelist','');if(changelist)location.href='http://secretInternalPerforceHost/describe.php?change='+changelist;}

Good stuff.

Simulating the Bullet

While looking at accelerometer options, the question came up on how much acceleration the hardware needs to handle. For example, this DE-ACCM3D is a mighty tidy product but the measurement range is +/- 3G. RockSim to the rescue.

RockSim wireframe representation of my extended LOC/Precision Bullet

It was a little painful to build the extensions to the Bullet in detail, but it's in there now so I just give RockSim the launch conditions and tell it what motor to use and it performs the launch (mathematically speaking). According to RockSim, the Bullet, as I have it, will apogee around 745 feet with the G40W that I plan to use. The peak velocity will be about 200 feet / second and peak acceleration will be 175 feet / sec^2. That's about 5G.

I may want to pull off the electronics bay occasionally: the Bullet would then apogee over 1000 feet and hit nearly 250 feet / second with 6.8G. Or perhaps I'll attempt a Level 1 cert with the extended Bullet using an H55W: 2000 feet averaging 350 feet / second but only 4.5G... or burst off with an H180W: 2000 feet averaging 438 feet / second at 21G! Would be silly to fly an H without an electronics bay. With a Level 1 cert completed, I could then put an I in... too scary to even simulate. :)

Thursday, October 26, 2006

Firefox browser and plugins

I've been meaning to try out Firefox as a serious tool, but haven't taken the time yet. Mike has posted some info on Firefox that could help grunt like me get benefit - especially with the plugins.

Rockets Under Construction

The SpaceShipOne kit is still under construction. I picked up some plastic model putty, so I hope that I can get those melt points fixed and finish the paint / decal job. The big 'n scary part was getting the wings on straight, but that went well and I just need to pretty it a bit before flying it. Isaac has a parachute man that is ready for flight in SpaceShipOne - hopefully this weekend.

I've been waiting for a chance to put some sanding sealer on the wings of the dual-chute kit. The model went together well and I am excited to see it fly, but the wings primed to some serious ugliness. I have the sanding sealer, but it has been too cold at night to open the windows and put it on. There are connectors to, what looks like, boosters which each contain a chute.

Isaac's Renegade now has all 8 fins and 4 pods installed; there is no way that beast is going to fly straight! Parachute man is going to take a ride in the Renegade, but probably not with both boosters in use. We hope to take a couple flights with B6 motors this weekend (we have B6-0 for the first stage boost and then B6-6 for the upper stage).

The motor mount for the LOC Bullet is finally done. I added the U-Bolt because the kit came with the LOC SCM-1 mount kit for the shock-cord but since I intend to add an avionics or payload bay I needed a different solution. Another addition is the Aero Pack Quick-Change motor retainer; the kit uses no motor blocks and expects the user to friction fit all motors, but I'd rather have a simpler retention mechanism. The fin tabs had to be trimmed since they but up against the center ring which moved forward 3/8" with the addition of the motor retainer.

picture of rockets currently under construction

Wednesday, October 25, 2006

Look at those thin lines!

board trace for rocket harness of Roctronics That tiny line that goes between the leads on one of the connectors... I'll screw that up making my own boards. No doubt about it.

Tuesday, October 24, 2006

Hobby Constraints

I searched the local city and county (online) records and didn't find any specific local ordinance about rockets. The FAA rules apply, so I'll have to follow those constraints: a rocket weighing less than 16 ounces and having less than 113 grams of fuel can be flown at anytime in a park with appropriate dimensions; a rocket weighing between 16 and 53 ounces or having between 113 and 125 grams of fuel requires notification to nearest air-traffic control center; if the rocket weighs more than 53 ounces or contains more than 125 grams of fuel, then FAA must grant permission.

I write this here as a personal reminder to myself because I will forget.

Hybrid Power

Michael pointed out this excellent site and their info on hybrid motors. Specifically, that hybrids have similar total impulse ratings but the flights are quite a bit different. I needed to see how the difference really played out, so I 'built' my LOC/Precision Bullet using a trial version of RockSim.

For my first flight, I chose the SkyRipper Systems H124 which has a total impulse of 220Ns. I ran 3 test flights and each went a little over 1900 feet.

The second flight used the Aerotech H123W which has a total impulse of 211Ns. It is interesting, although not very important to me, that the Aerotech motor is 7.5 inches long, but the SkyRipper is 24 inches long. Again, I ran 3 test flights, but each went over 2300 feet with the solid propellant.

This is my first real simulation with RockSim, so I could be totally misunderstanding the data. I'm not throwing out the idea of hybrids, but I may think more seriously at Aerotech RMS for a while.

Launch Log 2006.10.22

This was my first time launching at a group launch. The club was the Colorado Rocketry Association of Space Hobbyists - they were pretty friendly and very helpful when I had some trouble with my ignitors.

We had a first flight of Pencil - we didn't get a launch shot of it because of the ignitor troubles. Since it was the first flight for that kit, I chose an A8-3 motor. The model flew straight and returned nicely.

The next flight was the red and yellow rocket that we have now named Mighty Mouse (which is probably a trademark for someone, so don't confuse my rocket with any companies). I love Mighty Mouse and I chose a C6-5 to give it some altitude...
Mighty Mouse leaving the pad smoke trail left from Mighty Mouse

Mighty Mouse went higher than any we have launched in recent history. In fact, it was a little breezy, so we have quite a walk to find it. There was plenty of open space and we did find it after just a couple minutes.
hunting for Mighty Mouse after a mighty launch

The last flight (because it got too windy and everyone packed up) was Pipes. I went with a B6-4 because I thought it would be too windy for a C, but I wanted to get up in the air again on something more than an A. The boost was straight, but we drifted again on the return. One of the shrouds came loose and the chute got a little banged up, so going to replace the chute on this.
Pipes leaving the launch pad

Friday, October 20, 2006

Wednesday, October 18, 2006

Mini Hybrids

While on the subject of rockets... I am fascinated by hybrid motors. Hybrids use a little bit of something-that-burns and then some nitrous oxide. There are many styles of hybrids, but I started reading about mini hybrids and - whoa - did you know that people make their own whipped cream!?
iSi Whip Dispenser iSi Whip Chargers

So in the motor shown below, you put one of those N2O chargers, some acrylic tubing, and igniter stuff into a motor casing and you are ready for a 11 NS rocket flight! Depending on how many launches the nozzle and casing last, it may actually be cheaper to go hybrid even for the C because the acrylic and chargers are so cheap! That's some wild stuff.
picture of Aerocon Systems Scream Mini-Hybrid

Monday, October 16, 2006

Launch Log 2006.10.15

We put the Red and Yellow Baby Bertha kit in the air today. I enjoyed building and painting the kit and it flew great! The first flight was using an A8-3 to make sure it went up straight before testing with a more powerful engine. The second flight was with a B6-4 and it was most impressive. Not only did the rocket go up straight, but the calm weather allowed the rocket to land very close.

Here is a pretty picture of Pipes; notice again the pipes instead of the fins. Whatever the magic there is, this rocket shoots perfectly straight. A large version of this will definitely be a project to use as a stable test platform for electronics and other airborn ideas (i.e. cameras and camcorders).

Not normally a good idea to catch rockets coming out of the sky, but coming in nice and slow on a full chute and weighing only 2.1oz, it was fun to watch Isaac attempt to catch the rocket.

We launched Quark and another tiny (RTF) model on A10-3T's - heh. Quark went out of site and the event puff wasn't enough to guide us to its landing. Shanelle suggested that our first bit of rocket electronics needs to be a beacon :)

Sunday, October 15, 2006

Construction Lessons Learned (Model Kits)

It has been years since I built rockets, so I forgot a lot of little things. Here are a couple brutal new lessons that I got: putting on the acrylic clear coat too thick causes some funky bunching and I need to look into my choice of plastic cement.

These two pictures show the funky bunching that I mentioned. It happened on a couple models but not on others. I came to the conclusion that I put the acrylic clear coat on too thick by reading some construction / finishing tips at other sites (i.e. InfoCentral @ RocketryOnline and John Coker's Kit HOW-TO).
little spot on the nose cone bunched up there is a line of wrinkles bunching along the side of the body tube

I was pleased at how the Space Ship One was looking and then I noticed some of the plastic had melted where the centering rings for the motor mount are! I either applied the glue too thick or am using the wrong type of plastic cement. I'm using Testors brand 'Cement for Plastic Models', so it sure seems to me I should have been fine!
the plastic at the motor mount center rings has melted

Saturday, October 14, 2006

Launch Log 2006.10.14

The line-up of what we launched today. We had to leave a few at home because the launch lugs or paint jobs weren't complete.

We flew this little yellow guy a couple times. The first flight, the motor retainer blew off instead of the nose cone, so it 'core sampled'. It came with extra motor retainers, so I guess that was expected. It went on to have another nice launch.

Isaac had named this one Purple Buzz. Unfortunately, we accidentally put a B engine in rather than the A we had planned on putting in it. It went out of sight and the grass was 10 inches high - we looked for quite a while, but failed to recover it.

The blue rocket with the pipes instead of fins (we call it Pipes) flew as beautifully as we could have hoped: straight up with a hint of a whistle. No troubles with chutes or anything - great rocket.

Nixie Tubes

Nixie tubes sure are pretty for glyphs:

picture of 50mm tall nixie tubes with numbers on them

picture of clock built by C. Schramm using both Nixie tubes and blue LEDs

I see them referenced occasionally and can't quite figure out if I am facinated by them because of the pragmatic design (10 wires in a tube: 1 for each number 0 to 9) or because they are old and that's cool. Likely, is simply because they are old and cool. Brilliant use of retro Nixie tubes and blue LEDs in that second clock above!

Speaking of pretty... not only are these rockets themselves an impressive achievement, take a look at the motors:

Freeze Frame lifts off using a heavy thick smoke BAMF lifts off using a blue flame and screaming engine

The pretties are fun, but rocketry is interesting to me because it has got my imagination running wild. There is so much technology and opportunities involved! I love this picture because it shows a regular guy that has attempted an altitude record with his rocket and now has to find it with that little antenna.

Active guidance for stability or running through rings is interesting for the code involved. And of course, there is a lot of electronics involved - bonus!