Saturday, October 31, 2009

Near Space Horizon

(Click on image to see a larger image)

This is my first attempt to limb sound from near space. These images were taken every 10,000 feet and stitched together. I tried to select the best, where the camera was pointed in the same direction. As you can see, they don't all line up properly, but it is a start.

In the future, I'll fly a sun sensor to let the flight computer align the camera properly. I also need to calibrate the field of view of the camera so the horizons can be properly aligned in the images (the horizon is depressed in near space - my photo montage assumes the horizon is not).

I'll put an article together for Nuts and Volts on this line of work. I assume it will be useful for detecting haze layers, including volcanic ash, in the future.

Wednesday, October 28, 2009

CheapBot Radio Antenna

Today I'm planning to solder the antenna for the ChepaBot radio controller. I purchases a SMA to SMA extension cable from Jameco for this. I'll cut the coax cable in half, peel back the inner conductor adn outer jacket, and solder wires to them.

The radios opewrate at a frequency of 434 MHz. If I take that frequency and divide it into 486, I get the proper length of the antenna (which will be a dipole). That comes out to 1.078 feet, or 12.936 inches. Divided in half and I get each element should be 6.5" long.

You can find an antenna calculator at

Monday, October 26, 2009

RC for Robots

I'm soldering a test board for a robot radio. To use it, you program a robot to respond to one of eight messages sent by the hand controller. The robot has its own radio and will reply back to the messages you send it. The handheld controller will have an LCD so human readable messages can be displayed.

The hand controller communicates with your robot like we communicate with rovers on Mars. Messages sent to the rover are acted upon, but intelligently, not as an automatic reponse like an RC car. That way, if you send a message to drive off a cliff, the robot can analyze your message and refuse to comply. Not only will it refuse, it will also send a message back about why it isn't complying.

Thursday, October 22, 2009

Robotic Arm

I'm working on a simple robotic arm design for the CheapBot robots. It uses two servos, one to lift the arm and the second to pul a wire lasso tighter. The wired lasso is made from piano wire, so it naturally wants to spring open when the smaller servo extends the wires. Both ends of the wire lasso attach to the servo horn, so when it moves the ends of the wires one inch, the lasso expands by two inches.

I want to try a thinner wire. To make it simple to use, the lasso must be really flexible to wrap around the target regardless of how sloppy the positioning between the arm and the target is. The wire lasso also keeps the end of the arm very light, an important issue when you have a six inch long arm (you can build up a lot of torque for the servo to lift).

Rubber stoppers take out some of the slop in holding the target. I need to find a lighter weight "cushion" for this purpose and an easy way to mount it. I'll look into a foam rubber shirt for the end of the arm as a replacement.

I'll post some pictures soon.

Tuesday, October 20, 2009

NearSys 09G and H

Here are some images taken on last Saturday's mission.

This one was taken shortly after balloon burst. From around 80,000 feet, we're looking at the cloud cover over Melvern(?) Lake.

We're getting closer.....

Monday, October 19, 2009

Webpage Updates

I've started posting updates from the last near space mission. I'll massage some of the student Balloonsat data, but want to let them work their data over before I post the results.

Since it was two flights, there are two webpages for the results.

The only bad thing to happen was nylon zip ties failing and dropping one of the trackers (it's battery was dead by then). So it looks like I'll start some testing of zip ties in cold temperatures to see what I can learn from the experience.

Sunday, October 18, 2009

The Ft. Collins Balloon Story

I helped launch two weather balloons this weekend. They were for Univeristy of Kansas and Kansas Wesylan University students. Some of these students will become science teachers and because of this experience, they will launch BalloonSats for their students.

However, after listening to the Balloon Boy story out of Fort Collins, I can't help but wonder if this is going to impact amateur near space exploration. All it takes is for one irresponsible person to negatively change public perceptions of amateur science in general and near space ballooning in particular. If as a result, access to near space ballooning is stopped or limited, students who's only dream is to launch experiments into space will be denied the opportunity of reaching this dream by taking their first step into near space.

Gawker is carrying an expose on Mr. Heene from a former friend and it doesn't cast a favorable light on him. I can understand Mr. Heene's concern if the balloon got away from him and he wanted to get it back. That however, does not excuse reporting that his son was onboard as a way to get state and federal government to track it. Claiming your son is onboard also reflects a lack of forethought. What are you going to say once the balloon is recovered (and it will) and its discovered no one was onboard?

I hope the public realizes Mr. Heene is not the face near space exploration.

Friday, October 16, 2009


Last chase I used a D7 and Garmin GPS V. They sat on the dash and did a lot of dancing around during the chase. Today my students are helping me make a dash-mounted platform to hold the radio and GPS. They are mounted so I can read the displays from both devices, but it would be better to have a navigator go along to read.

The system is simple and starts up as soon as you apply power. That means no waiting to boot a PC or load software.

Thursday, October 15, 2009

NearSys 09F

We may be launching two near space missions this week. The flights are for the University of Kansas, School of Education and Kansas Wesylan Univeristy. The person who made this all possible is Pete Sias, the man who got me started in near space exploration 15 years ago.

The launch takes place Saturday at 8 AM from trhe KWU campus. You should be able to track the flight at one of this webpages.

Onboard will be five KU BalloonSats and at least one experiment from the KWU Physics club.

I'll be flying the reuseable lunch bag tracker I'm developing for Popular Mechanics, an old backup tracker, and a module with a new flight computer. This module carries most of the science. It will measure cosmic rays, weather conditions, internal temperature, and several cameras, including still and video.

Friday, October 9, 2009

CheapBot MagArm

Using DALPro presensitized copper clad and ARES Lite, I created the magnetic robotic arm for my line of cheapBot robots. I used a Dremel drill and its drill stand to drill out the board. The PCB still has to be populated and I hope to do that this weekend. A reed relay (and anti-kick back diode) powers the electromagnet. The PCB has drilled holes for mounting the arm to a servo. The servo allows the arm to be raised and lowered. The lifting servo and arm can be mounted to a second servo to allow the arm to rotate. But for beginners, I recommend using the robot to rotate the arm instead.

The CheapBot MagArm will allow robots to pick up slightly modified ping pong balls. This gives students the challenge of programming the robot to pick up stuff without spending more time trying to make the system work mechanically.

Thursday, October 8, 2009

Smart Proximity Detector

The Smart Proximity Detector I have developed uses a PICAXE-08M to control the blinking of two IREDs. The detector mounted in the middle of the PCB determines if there is a reflection from the IREDs. Since the PICAXE controls when and how fast each IRED blinks, it knows what condition created the reflection. The detector is most sensitive to 38 kHz IR and gradually gets less sensitive as the frequency gets off center. This gives the PICAXE a way to "estimate" a distance to the reflecting object and if it is located across the robot, or just on one side or the other. Not only can an object be detected across the robot, but if there is significant difference in the distance on the left and right side, that can also be determined.

The boards tested fine, so look for kits on shortly.

Wednesday, October 7, 2009

Magnetic Robot Arm

Last night I came up with a solution for a lightweight, but inexpensive robot arm for CheapBots. The arm is 0.6 inches wide and 5 inches long. Its grasper will be switched for an electromagnet. A relay will control the current for the magnet since the robot controller cannot provide that level of current. The arm will be light enough that a small servo can raise and lower it. The servo and arm will be turned on side, but a second servo could be mounted below to allow the arm to rotate about the horizontal plain.

I'm looking into hall effect sensors now as a way for the robot to detect the presence of a magnetic field. That should help the robot align its arm, because the objects it will pick up will be ping pong balls with small neo magnets glued inside (the bottom of the ball will have a cut hole so it doesn't roll).

Perhaps I can shoot the PCB for the arm tomorrow.

Tuesday, October 6, 2009

NearSys 09F Winds Aloft

This chart was developed from APRS data (positionn reports) transmitted by the near spacecraft. As you can see, the winds aloft were preetty strong and the thickness of the high speed winds was pretty large. No wonder it recovered 112 miles away!

Monday, October 5, 2009

NearSys 09F

Here are a couple of images from my last mission.

The balloon has burst and we're parachuting back to earth.

This is on ascent. The near spacecraft has just broken through the clouds.

Sunday, October 4, 2009

NearSys 09F

NearSys 09F reached an altitude of 79,414 feet. It recovered 112 miles away, further than we were planning. That's because the jet stream was much faster than expected. That along with the traffic jam near the end of the turnpike made for a slightly frustrating recovery. Once we got everyone together, we drove to the last know location (4,000 feet AGL) and figured the near spacecraft drifted another 1/2 mile. Once we got close, we began picking up packets again.

The tracking modules based on the MicroTrak 300's had trouble getting packets to us during the chase. However, the APRS gateways put plenty of packets on the Internet. Um, this calls for some investigation. If you know of someone who can help me analyze the radiation pattern and strength of the transmitter, please let me know.

I'll post more information on Washburn's first near space flight in the next few days. There will be a full report on my website.

Friday, October 2, 2009

Washburn University Launch

This Saturday I'm helping Washburn launch their first near space mission. Since I completed the tracker for my Popular Mechanics article, I'm going to send it up for a real test. I'll add an additional two trackers as backup. I believe in using two trackers, in case one fails and since this will be the first flight of the Pop Mech tracker, I'm sending the two trackers as back up for it.

The three trackers are transmitting as KD4STH-4, -8, and -9. The frequency for all three is 144.390.

In addition, this mission will carry the thermopile telescope I designed. It also has a weather station like the kind I'm selling, two video cameras (one pointed up and the other pointed down), digital still camera recording horizontal pictures every 15 seconds, and an accelerometer.

I'm looking forward to a fun flight. If you're in the area, come on out.