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Experiment Goals
The goal of my senior project is to study the meteorological conditions that exist in lower atmosphere. In order to collect the necessary data, the metrological balloon will be sent with a payload to an altitude of 80,000 feet. The payload weighs five pounds and contains sensors that measure temperature, altitude, UV radiation, and atmosphere pressure. It will carry two cameras to take aerial photos of the horizon from “near space,” the region between the boundary of space and the earth’s atmosphere. Once the payload lands, a recovery team will use the tracking system to recover the video record and the data from the payload.
Payload Design
Overview
‘Chollian’ is a Chinese term meaning EYE THAT CAN SEE THOUSAND LI (Li is a Chinese unit of distance – 1000 Li is equivalent to about 400km). As of May 20th, there have been four different payload versions : Chollian07, 08, 09, and 10
. The second vehicle, “Chollian08,” was built lighter – 6 pounds. The first launch was attempted on April 19, but it was unsuccessful because the balloon did not provide enough lift. The third vehicle, “Chollian09,” was launched on May 3. The weight of this vehicle was only 3 pounds. It reached an altitude of 26277.56 feet and descended.
Chollian07 Design
The first vehicle, Chollian07, included the most sophisticated payload built, but was never launched because it weighed nearly 10 pounds and therefore conflicted with FAA regulations. (Click here to see FAA regulation afflicting unmanned ballooning)
Container
The container of Chollain07 was plastic laundry box, roughly 45 cm by 20cm. In order to withstand the extreme temperature and wind current of the upper atmosphere, bubble insulation was used to cover the surface of the container. Econokite, a blue cohesive covering material, was used to tighten the surface.
Ø Tracking System & Recovery Aid device
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| USB 900Mhz Radio receiver | STXe Transmitter |
The Tracking system was the key part of this project. I purchased a GPS flight STXe transmitter (left) and RxUSB Base station (right) for $ 1028. the STXe transmitter unit is very light. It weighs less than one pound and contains the GPS, Altimodule, and 900Mhz radio transmitter. It receives GPS coordinate from satellites using its GPS patch antenna; then, it retransmits many variables, such as GPS coordinates, altitude, pressure, and temperature to the RxUSB Base Station. The base station has a USB plug and a 5 inch radio antenna. The maximum transmission range is about 75 miles in line of sight. The USB Base station is powered by the USB cable. Incoming data from the transmitter is displayed on the computer screen. The data can be logged into portable computer. To locate the vehicle’s landing position on a map, I purchased Microsoft Street 2006 which is powerful offline mapping software. Plugging GPS coordinates (longitude, and latitude) into this software allows me to accurately locate the payload. Chollian07 carried one stereo speaker to aid in the recovery process. I predicted that radio transmission between the transmitter and the base station would be interrupted once the vehicle approaches the ground within 3,000 feet; the final GPS coordinate would be off from actual landing point by 500 feet due to geographical reason. If the payload lands in woods, the recovery process would take longer and be more difficult. The stereo speaker played the song Die Walkure Walkurenritt Furt194, repeatedly and loudly enough to aid the recovery process. This song is Apocalypse Now’s theme music.
Ø Video Recording Devices
Visual recording devices are important. Another goal of my senior project is to acquire amazing aerial pictures of near space once the vehicle reaches 80,000ft, and above. Chollian07 carried two webcams and one micro CCD camera. The two webcams were connected with the flight computer and the micro CCD camera is connected to a portable media player. Webcam # 2 was mounted inside of the vehicle to record the weather station monitor. Webcam # 1 was mounted at the bottom of the vehicle to record an outside view. The camera is capable of recording a movie of 30 frames per second, and capturing a 1.0Mega pixel quality still image, and can be rotated 180 degrees left or right and 90 degree up or down. Unfortunately, the rotating mount function is uncontrollable from a remote distance. therefore I did not plan on working on the rotating function. The flight computer commands both Webcam #1 and # 2 to take a snapshot every 5 seconds; images are saved to hard drives. The Micro CCD camera was mounted at the top of the vehicle in order to record outside motion video. Motion video requires a process called finalization. If the portable media player’s power supply is disturbed before finalization, video data will be lost, so, I decided to use segment mode. The segment mode saves the video in different file every 150 minutes.
Ø Sensors
Chollian07 carried four external sensors: a weather station unit, responsible for measuring UV radiation, outside temperature and air pressure and a GPS unit, responsible for measuring internal temperature, altitude, and the vehicle’s movement. These data are collected on the flight computer and the base station during the mission. Originally, Chollian07 was intended to carry a wind sensor, which measures wind speed and direction. Because of a budgetary problem, the plan has been aborted
Ø Electronic & Power supply
Here I am testing the onboard stereo system. It is needed for helping to retrieve the vehicle once it hits the ground. Since there is no AC power supply onboard, I created my own power supply for the speaker. An RC Airplane 8.4v 1600mh battery, works perfectly
The onboard power supply was the trickiest part of my project. Some of the instruments required very a high voltage. The stereo speaker, for instance, required 12 Watts of power. My remote control airplane battery was used for the stereo speaker. The battery lasted about 7 hours, but there was high risk of the fuse burning. I therefore was very cautious when I handled the RC battery. The flight computer needed the heaviest battery, called a universal external battery. It weighs almost 3 pounds and is supposed to power the computer for 16 hours. The flight computer was my old Samsung SENS 830 model laptop. Its internal battery lost its performance long ago as a result of “memory effect” a battery capacity loss phenomenon. I tried to buy the same battery, but since this laptop model is old, Samsung no longer sells any of its accessories. A universal battery was too heavy, so I planned to add one more balloon because the vehicle gained so much extra weight.
Building the flight Computer was challenging. Since the LCD, and Keyboard of the laptop were gone, I had to use a network remote control function to control the computer. The laptop had a notebook wireless adapter plugged in. I set the wireless card to transmit its own signal. This mode of transmission is called “Peer to Peer connection.” Using peer to peer wireless required me to set a manual IP for both the flight computer and the base station computer. The fight computer was set as “192.168.9.2” and the base computer was set as “192.168.9.1.”
My laptop weighed 2.5kg. It was too heavy to be on board. so I disassembled the LCD from its main frame. On day 2, I started to break down my laptop. I was very careful about it first, but after I broke the first piece I destroyed the rest in seconds.
This is a picture of disassembled laptop. The deconstruction process reduced 50% of its weight. In addition, I took out the CD-Rom slam bay and internal battery. I was still able to see the screen by connecting the laptop with a parallel port to other monitor I have.
Converting my old laptop into an onboard computer was very challenging. First, I decided to detach the LCD screen, Floppy Drive, and CD-Drive. However, it was still too heavy. So I even took the plastic laptop casing. Then I realized that the motherboard was the only thing left over. It was less than one pound. In order to operate this during the flight, I had to use a sharp object to trigger the power button. Then I established an ad-hoc wireless network to create a remote connection between the flight computer and the base station computer. After turning on the video monitoring software, the vehicle was ready to fly.
Ø Parachute
A recovery system is necessary when something is dropped from 100,000 feet! I purchased a 6ft circular parachute for this vehicle. As the diameter increases, the drag increases as well. A drag estimate can be found by using Parachute descend rate equation FD = ½ r Cd A v2 FD is the drag force, r (Greek letter “rho”) is the density of air = 1.22 kg/m3, , Cd is the drag coefficient, A is the area of the chute, and v is the velocity of the object.. With a 6ft parachute, Chollian07 would descend at 14.5 mph. Estimated descent time from 60,000 feet was one hour.
A 12 ft diameter parachute
Ø GAS
Helium and Hydrogen are gases popularly used for ballooning. Hydrogen is cheaper than helium and easily accessible. However, it must be handled with caution since it is flammable. I planned to use Helium for filling a weather balloon. According to my research, 1 liter of helium can lift slightly less than 1 kg.
I originally thought that each of the weather balloons would require one full tank of Helium. Later I found out that a a T-size tank can fill two weather balloons. Helium tank can be rented from the hardware store in downtown. They have two different tank size for Helium: K-size, with a volume of 219 cubic feet, and T-size, with a volume of 290feet. One K-size tank costs $115.00 to rent.
Ø Predicting flight path & Selecting Launch area
I predicted that Chollian07’s flight path would be directly affected by the jet stream. I was able to observe jet stream in the region by visiting http://www.wunderground.com. Based on observations from March 2nd to March 9th, the jet stream inNew England blew from the west to the east. The wind speed was varied from 50 to 60 mph. On stormy days, however, it rose up to 200 mph. The webpage allowed me to see the wind speed and direction at different altitudes. I was concerned that the jet stream was blowing toward the Atlantic Ocean because the distance from the Atlantic shore and our school is only 100 miles, the balloon might have landed inAtlantic Ocean if I launched from Holderness during month. So, I decided to move the launch point 70 miles to the west from Holderness campus, inRuthland,VT. I calculated the wind data from the webpage and predicted that the balloon would land somewhere near Holderness if launched from Ruthland. Chollian07’s launch was, however, postponed until April. The senior project committee decided to postpone the launch because no faculty member was able to give me a ride.
The jet stream during April 8 to April 17 still blew from the northwest to the east, but the wind speed was lot slower than that of March. I changed the launch location back toHolderness School. I also found out new way to check in real time the wind direction and speed.Bangor flight service station was very helpful resource. I just had to call 1-800 – WX- BRIEF. The operator kindly answered my question whenever I called for information.
> Ballooning & FAA & Launch Process
I purchased four 2200 gram ML-541A/AM weather balloons manufactured by Kaysam Industries in 1982. Each of the balloons cost twenty dollars from ebay. Based on the seller, one balloon filled with one tank of Helium created 7.5 pounds of lift. From the Chollian08 launch on April 19, I found out that the balloon weighed 5 pounds; therefore, there was only an additional 1.0 to 1.5 pounds of extra lift. I basically realized after the launch attempt of Chollian08 that I totally miscalculated the lift of balloon. I planned on using two balloons and one T-size helium tank (219cubic feet) in order to launch Cholian.
The day before the launch, I found out from the FAA that I would need a waiver for launching any payload heavier than 6 pounds. Chollian07 was already 10 pounds, So I had to call the FAA for wavier. I was able to find local FAA facility phone numbers on the FAA internet webpage.Plymouth Municipal Airport andLaconia Airport do not have air traffic controllers.Holderness School was located in the middle of two air traffic controllers -Lebanon Airport and the Bangor Flight Service Station inMaine. Getting a waiver was not an easy process. I called theLaconia air traffic controller (603-298-8878) first. The operator responded with an irritated voice. He forwarded my call to the Bangor flight service station(207-947-3349). The operator at theBangor flight service station told me to call the Boston Air Routine center (603-879-6811) for the waiver. The operator at Boston Air Routine center told me to call toBurlington MA (802-951-6718) for all balloon launches. FromBurlington MA, the operator forwarded my call to the Flight Standard District Office inMaine (207-780-3263). The old lady who responded to my call told me to call the New York number without even listening to what I was sayings.I called theNew York number (718-553-4521), but nobody answered the phone. It was like a FAA telephone marathon. I finally called back Mr. Collin Scoggins at theBoston Air Routine Center, and he suggested that my payload stay under 6 pounds so that I would not need a waiver. I gave up looking for a waiver, and the launch plan for Chollian07 was aborted.
Chollian08 Design
Chollian08 was built lighter than Chollian07 in order to comply with FAA regulations. The vehicle weighed 5 pounds. I attempted to launch Chollian08 with the help of faculty members on April 19, 2006. It was the first launch of my senior project. Unfortunately, we did not do good job in inflating the balloons. In addition, the vehicle did not work properly. The launch was unsuccessful.
Ø Tracking System & Recovery Aid device
In addition to the original STXe tracking devices, I added a telemetry tracker or “Dog Tracker,” to Chollian08. Dog tracker is professional tracking unit for dog hunters. It comes with a transmitter and receiver. The transmitter requires one 3.0V photo battery, while the receiver contains an omni directional antenna. It generates a louder beep noise as one approaches the transmitter. I believe the maximum transmission range is around 7 miles. The dog tracker replaced the stereo system that was built on Chollian07.
Ø Container
Chollian08 was built lighter. I tried to eliminate as much weight as possible. The plastic container used in Chollian07 was already one pound by itself. I therefore decided to use a cardboard box. Bubble wrap and Econokite insulation were used to cover the surface. The volume of the container was very small. Everything was tightly packed together inside.
Ø Video Recording Devices
Chollian08 did not carry flight computer and web cams. Since the battery for the flight computer weighs too much, I decided to carry a camcorder instead. The camcorder only weighed 2.5 pounds. In addition to the camcorder, the micro CCD camera from Chollian07 was attached to the vehicle’s long arm. The micro camera faced toward the vehicle, in order to capture the weather station monitor. A Portable media player was used for recording video. The segment time was set for 150 minutes.
Ø Sensors
Sensors in Chollian08 were same as before.
Ø Predicting flight path & Selecting Launch area
On April 19, the wind blew north at 50mph. The launch location was the Holderness School quad. If the launch was successful, the payload would have landed in the White Mountain area. The weather was sunny and the sky spotless. It was, however, windy on the ground level. We needed many people to secure the weather balloons.
> Ballooning & Launch Process
In the morning of April 19, We rented the T-size helium tank from the downtown hardware store. I was excused from every class. So I could focus on my launch. The tank only cost $50 that day because the employee miscalculated the price. Thankfully, I was able to receive help from many faculty members and students. To inflate the balloon, I made the adapter by connecting standard gas tube and sprinkler. We ripped the first balloon accidentally because we turned on the helium gas valve too fast. The tank was compressed with tremendous pressure and the valve was very tight. We tried to open it with force, and then the gas just burst out of the tank and ripped the balloon. The second balloon was popped in the middle of inflation process.
.We successfully inflated the third balloon. To tie the balloon, we used zip ties several times. Zip ties worked perfectly, but the third ballooon did not have enough lift for Chollian08. In addition, we exhausted our supply of helium. The launch was unsuccessful. Later, I realized that the GPS and many other sensors were not working at that time. There was serious problem with the GPS unit. I could not get satellites locked into the GPS for some reason. The following day, I had to send the STXe unit to its company’s factory. Other instruments had a low battery problem. Because the inflation process took nearly 2 hours and I turned on the instruments before the balloons were ready, the batteries died early. This project could have been a disaster if we had actually launched. Another problem I noticed was location. JV baseball had a game at 2:00 and we occupied the field until 1:40. JV baseball coaches were frustrated. Ms. Pfenninger’s car was parked next to blue plastic baseball fence and I had trouble running around it whenever I needed to check the receiver.
Learning from PSU Meteorology Department
Following the failure of Chollian08 launch, I needed an explanation as to why things went wrong and Dr. Mumford introduced me Plymouth States University meteorologist, Dr. Zabransky. I did not know that PSU has one of the best meteorology department in the United States. I asked Dr. Zabransky many questions on the phone for thirty minutes and was invited to a PSU weather balloon launch on May 2.
On their launch day, Ms. Pfenninger drove me to PSU’s south soccer field and we met Dr. Zabransky and his team. Their launch was in smaller scale than my launch. They launched a payload called a radiosonde. It is small package of instruments that measure temperature, pressure, humidity, altitude, and GPS coordinate. I was surprised that the radiosone only weighed half a pound and cost only $ 125, whereas Chollian08 weighs 5 pounds and costs nearly a thousand dollars. PSU meteorology department’s mobile station was amazing. It was the van that carried large GPS and radio receivers with a tripod attached, two tanks of helium, the power generator, boxes of replacement parts, computers, the gas step-down, and the special balloon nozzle adapter for inflating balloons. Interestingly Dr. Zabransky and his team were not planning on retrieving the radiosone. It was rainy day, but Dr. Zabransky did not seem to care about the weather condition. They used a “pilot balloon,” which is a lot smaller balloon than my “sounding balloon.” and did not have any trouble inflating the balloon. I noticed that they had a device called a gas step-down to prevent sudden gas burst from the tanks. Dr. Mumford joined me when Dr. Zabransky finished inflating the balloon. She and I thought that their technology was amazing. Another cool thing I saw was radiosonde’s battery. The battery is extremely light, but its capacity is amazing. It generates electricity by reacting with water. Dr. Mumford thinks acid-base reaction is the source of the battery’s energy. The battery only needs to be dipped into a cup of distilled water for minute before the launch and can last for two to three hours. I thought this was brilliant idea. Unfortunately, their radiosonde had a technical problem. It could not communicate with the ground station. After two attempts, Dr. Zabransky decided to abort the launch. Since he already inflated the balloon, he just let it go in the air. Although Dr. Zabransky’s launch was unsuccessful, I learned a lot and gained confidence for my incoming launch on May 3rd.
Chollian09
Chollian09 was the first successful vehicle. On May 3rd, I and many members of the faculty gathered at Quad again for second shot. It was rainy day, but the wind was very calm. We came up with two plans. Plan A was to launch the entire payload. Plan B was to unload camcorder from the payload and launch. Plan A did not work out. So we went with Plan B. Chollian09 weighed only 3 pounds when it lifted off.
Ø Container
Chollian09 was similar to Chollian08. The cardboard box for Chollian09 was slightly bigger than that of Chollian08. The box was covered with metal tape and Econokite covering. Bubble wrap insulation was used inside the container. I did not want to pack instruments in tight space because it was very difficult to change the instrument setting or change batteries before the launch. I also damaged my GPS patch antenna as I grabbed one instrument out of the box of my last launch. Chollian09 had extra room inside and was easy to open.
Ø Predicting flight path & Selecting Launch area
Dr. Zabransky gave me a link for the PSU weather station. It was a useful webpage for looking up wind information. On May 3, the wind was blowing west at around 40 to 50 miles per hour. My predicted landing area was Lebanon, NH.
Ø Sensors & Video Recording Devices
The video system and sensors in Chollian09 were same as these in Chollian08. Only the position of the UV sensor was changed.
Ballooning & Launch Process
My launch team did not make any mistakes, moved quickly, and successfully inflated all four balloons without even popping one. Inflating four balloons required two full tanks of helium. Unfortunately, the tanks cost $285 which was so much more expensive than last time. The inflation process began around 1:00 and finished around 2:00. The bus was parked on the perfect spot. I did not have to run around the fence.
Four balloons did not provide enough lift for Chollian09 at first, so I had to unload the camcorder, which weighs 2.5 pounds. Chollian09 weighed 3 pounds right before its lift off. At 2:15, Chollian09 started its adventure.
Part 2 Action!
Breathless tracking
For the first 10 minutes, Chollian09 ascended slowly at about 130 feet per minute. We watched it going up until it disappeared into the clouds. Chollian09 was flying 1,500 feet above at downtown Plymouth 10 minutes after the launch. It disappeared into clouds at around 2,300 feet. That was when we departed from campus.
Chollian09 headed west at about 9 miles per hour. We knew roads very well, so found a shortcut that allowed us to get ahead of the balloon. The balloon ascended faster as it went higher. 30 minutes after the launch, as we were driving on route 25 West, and Chollian09 was passing by Plymouth Municipal Airport, the altitude was about 10,000 feet. The vertical speed indicator showed 7.5 miles per hour.
After an hour and five minutes, Chollain09 was only 1.87 miles east from Route 118. It was still at a heading of 270 degree, and there was no road going straight west. We either had to take route 25 or 118. We stopped the bus near Cheever and suggested the wait for another 15 minutes to see a better flight path. Chollain09 reached 25,750.98 feet at that time. We got out of the bus and tried to spot it with our eyes, but it was too high.
After an hour and six minutes past launch, I noticed a big drop in altitude. I first thought the transmission was delayed, but my altimeter kept indicated a drop in altitude.
When Chollian09 reached 23,000feet, I realized that one of the balloons had popped.
An hour and sixteen minutes after the launch, Chollian09 reached 15,843.18 feet, had just passed Route 118 and was descending at 13 miles per hour. Cummings Pond was only 3.64 miles away from the vehicle. I became more anxious.
Hiking with motivation
We were looking at the mountains that are about 1,900 feet high. At this rate of descent, I predicted that it would land near Cummings Pond. My map showed the local roads in this area, so Wel drove to Dorchester and took a right onto North Dorchester Road.
An hour and twenty six minutes past launch, we lost transmission from Chollain09. The last GPS coordinate we received were (43.77281, -71.9784), and an altitude of 5,125.656 feet. The mountains and trees around us made the communication between the receiver and the transmitter difficult.
North Dorchester Road was very rough, and Cummings Pond road was closed to motorized vehicles. We believed that it was a logging trail. We decided to park the car at the junction of the two roads, and walked from there. I activated the telemetry tracker, or “dog tracker.” Amazingly, I received a strong signal. It was a sign that Chollian09 landed within 4 miles. We walked onCummings Pond Roadfor while, and then decided to bush hike toward the direction of the strong signal.
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Bush hiking was rough. We went bush hiking for nearly an hour and a half and ended up crossing the road twice. We found out that there were other trails that were not even on the map. The telemetry tracker indicated that we were only one mile away from the source. We thought it was unreliable at first so I checked my GPS receiver in case it had received another coordinate. Amazingly, I received a new coordinate. After looking at the GPS data, we figured the dog tracker was correct.
It was already five thirty. The sun was going down, and we were in hurry.. Chollian09 motivated me to walk forward. This was the first hiking in four Holderness years that I have ever done with such enthusiasm.
Veni, Vidi, Vici!
We hiked for nearly two and half hours. The dog tracker indicated that we were within 300 yards, but there was no sign of Chollian09. We suggested we climb higher to get better view. There, we saw two weather balloons in distance. Veni, vidi, vici!
We basically ran from there to the landing site. Amazingly two out of four balloons were still afloat and the payload looked perfectly fine. The balloons, parachute, and payload were still in one piece. The only problem was that everything was caught in multiple trees that were 20 feet tall.
It took us three days to get the package down off the tree top, and I am not going to tell you how we did it.
Mr. Kendall helped me three days in a row. When I thanked him for helping me, he said “Getting down those balloons has become personal.”
On the way back to the school, We stopped by McDonald and ate Big Macs. We were so hungry that everything tasted great. It was like eating OB Big Macs after OB.
Chollian09 did not reach the goal altitude of 80,000 feet. I determined that one of the balloons prematurely popped. Dr. Zabransky once told me balloons I bought were stocks from 20 years ago. The balloon is made of totex rubber and it can deteriorate after many years. From the experiment of Chollian09, I gained confidence in tracking balloons. I am hoping another mission for aerial photography in future.
Part 3 Analysis
Chollian09 Post Flight Analysis
Success
Chollian IX provided excellent positional data. Our tracking path was very effective for communicating with the GPS unit onboard. The ascending rate was fine. The UV sensor partially succeeded in logging the high UV record.
Failure
Two of the four weather balloons popped prematurely at 26277.56 feet, which caused descending too soon. These balloons were at least 20 years old. Dr. Zabransky believes that the age of the balloons may have deteriorated the balloons’ surface. The thermometer and barometer on GPS unit failed. Although the secondary thermometer and barometer worked on the weather station, PMP, which was supposed to log the screen, failed to finalize the motion video. So I could not acquire aerial images, thermometer, or barometer data.
Wind Data analysis
Chollian IX provided excellent position data. The GPS unit worked great and communication was established between the payload and the base station for most of the time. I was able to find wind data from the PSU archive. (http://vortex.plymouth.edu/sfcwx-u.html)
On May 3, the launch day of Chollian IX, the wind was blowing toward west around 10 to 20 miles per hour. It was very calm day.
Using Google Earth, I compared the horizontal and vertical vectors with wind data from PSU. Interestingly the 3D flight path of Chollian IX was closely matched with the wind data from PSU.
As you can see from this 3D image, the balloon’s flight path corresponded to the wind direction. The greatest horizontal movement occurred between 3 to 21 minutes after the lift off. If these time intervals were converted into altitude, they were around 2,728.018 feet to 6,578.084 feet. In fact the fastest horizontal speed was measured at the altitude of 3,727 feet.
The graph above represents the relationship between altitude and balloon’s horizontal speed. As mentioned earlier, the fastest horizontal speed occurred at 3,727 feet. At 15,000feet, the horizontal speed increased again into 20 miles per hour. The real wind speed might have been higher than the balloon’s horizontal speed since wind requires energy to push the balloon. The wind speed at 15,000 feet was around 35 miles per hour.
I also found interesting facts from the balloon’s vertical speed record. The rate of ascending seems to increase in higher altitude. During the first 5 minutes of ascending, the average vertical speed was 124.67 feet per minute. The average speed increased to 454.92 feet per minute at 5,000 feet, 487.728 feet per minute at 10,000 feet, and 666.666 feet per minute at 20,000feet.
The graph above indicates the relationship between altitude and vertical speed. The balloons popped at 26277.56 feet, so the next dots are marked below zero which means they are descending. The fastest vertical speed was 24.0682 miles per hour at 11676.2 feet. The table actually says 168mph at 19858.6 feet is the highest, but I concluded that it is a wrong reading from the GPS unit.
Ultraviolet Radiation Data Analysis
Because the video system in Chollian IX failed, I was only able to capture few variables from UV sensor. The launch day was a rainy day. The cloud ceiling at Holderness School was 1,000 feet above the ground. UV radiation index on the ground level recorded zero. The UV index is scaled from 0 to 26 and higher indicates dangerous UV radiation.
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| UV meter reading measured by ChollianIX |
The UV sensor at the maximum altitude recorded 18 out of 28. A UV Index of 18 is very dangerous for any life forms. Although the balloons popped so early that I could not measure the UV level at ozone layer, Chollian IX still provided evidence that UV
Extended Mission– ChollianX and its the Great success
Chollian IX, which was launched on May 3, failed to measure temperature and pressure data. Since these two data are very important for my project, I decided to launch one more payload – Chollian X. The primary mission for Chollian X was to take aerial photos of campus and record video footage. Its mission also included measuring temperature and pressure data. Remembering previous mistakes, Chollian X was more thoughtfully designed. I corrected the mistakes from previous flights. The balloon for this launch was brand new and was ordered directly from Kaymount Company. It cost more than the combined cost of all previous balloons. Chollain X carried a small radio controlled siren to aid the recovery process. A five megapixel digital camera was added to the bottom for capturing quality aerial images. The camera’s shutter was triggered by a radio controlled servo. The thermometer and barometer in the GPS unit were repaired. The container was lighter and stronger than Chollian IX. The total weight of Chollain X was four pounds. The Chollian X mission was not the part of my project plan in the beginning of the year. I had already run out of my budget. Thankfully my school granted my wish, and I was able to continue the last Chollian mission. Chollian X was the greatest success ever. In fact Mr. Kendall was quoted in the school’s webpage after Chollian X’s recovery: “[T]he final result it is one of the neatest things I have witnessed a student here do.” Chollian X set not only an altitude record which was estimated around 100,000 feet, but also set a distance record. Tracking Chollian X was a breathtaking chase. Mr. Kendall, Mr. Oldack and I had already become professional balloon trackers.
Launch & Recovery
The Chollian X mission officially started at 12:30 on May 17. I checked the wind aloft before the launch and found out the wind was blowing a north east at 50 miles per hour.
Ms. Pfenninger and I decide to prepare for the launch earlier than 12:30 because we heard it was going to rain afternoon. We picked up the helium tank from the hardware store around 10:40. The clerk at Rand’s hardware store knew before even we asked that we were there for another helium tank. We loaded one T-size helium tank into the van, and transported it to the quad. At 12:30, my balloon team came and prepared the site for the launch. Inflating this balloon was much easier and quicker than the last balloon. Remembering the last launch, we worried about having not enough lift since the payload was four pounds; however, this balloon was different. We were amazed that this single balloon created more lift than the combined lift of all previous balloons. At 2:05, Chollian X lifted off.
ForceMeter Measures Balloon Lift
The lift was very powerful. Chollian X ascended faster than I expected and disappeared into the cloud ceiling within five minutes. The payload violently swung from the wind, so that many aerial pictures came at blurry. We wanted me capture a shot of the Turf field, but the balloon rose too fast, so the turf field was barely included in one of the pictures. The average ascending rate during the first five minutes was 1059.8 feet per minute.
The biggest crisis came 25 minutes after the launch. The altimeter indicated 16,925 feet and the location was somewhere above Mountain Prospective Road at that time. Suddenly the GPS unit lost the satellite signal and stopped transmitting positional data (Longitude and Latitude). The Dog tracker was still working, but the balloon had gone up so far that the signal became very weak to detect. We decided to go ahead of the balloon by following the north east direction.
Chollian X was still transmitting the other data such as temperature, pressure, altitude, and vertical speed. The hopeless moment came when the balloon passed above 30,000feet. Chollian X has two ways of measuring the altitude. It can use GPS satellites , and the other way is using the altimodule, which converts the barometer reading into the density altitude. The altimodule has the device limit that it cannot measure the altitude above 30,000feet. We had been relying on the altimodule since the GPS unit could not find the satellite signal. 40 minutes after the launch, we were only getting pressure and temperature readings. It was disaster. In fact the entire project could have fallen apart.
At one point, we could not establish any communication for nearly 15 minutes; however, We did not give up, and used our instinct and dog tracker to find any hint of the balloon, and then we happened to cross the Maine border. An hour and a half minutes after the launch, the miracle came. We stopped at one open field near Fryeberg, MA to scan the dog tracker signal. My dog tracker receiver indicated that the balloon was very close. The radio sensitivity of my dog tracker was set at 5 out of 10 and it was still able to detect the signal. We struggled to decide if this meant the balloon was still on the air, or landed.
We scanned the dog tracker signal from three different open fields around the lake and discovered that the signal was coming from .3 miles north from the lake. While we were driving on Knights Hill Road, my computer received a new GPS coordinate from Chollian X. The GPS came back right at the important moment like a miracle. It confirmed that the balloon landed near the lake (the black mark on the map). Mr. Kendall suggested approaching the landing site with the car, so we took Smarts Hill Roadto its end and bush hiked to the balloon. The trees in this region were very tall like the last landing site, but we were well prepared this time. We brought an improvised device to recover the package from the treetop, walky-talkies and box of water bottles, the dog tracker and the radio transmitter for the siren. Bush hiking was very easy this time although we fell in the marsh couple of times. When I successfully activated the siren, Chollian X was making a loud alarm from the top of the tree as seen in the picture below. It was very helpful to locate the exact location of the package hung in the treetop. We cheered for our success. Mission accomplished.
ChollianX Post Flight analysis
Temperature data analysis
Chollian X discovered an interesting relationship between altitude and temperate. In fact I was surprised by the result. As I mentioned earlier, the GPS unit failed to receive positional data, and the onboard altimeter failed after 30,000 feet. The only reliable data were temperature and pressure. I successfully converted pressure data into altitude data by using atmosphere density altitude conversion. The density altitude is the altitude at which the density of the International Standard Atmosphere (ISA) is the same as the density of the air being evaluated. I used the webpage called Standard Atmosphere Calculator (http://www.digitaldutch.com/atmoscalc/index.htm) to convert from pressure to altitude.
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The barometer, however, also failed above 33,950.8 feet due to its device limit. Fortunately, temperature data was still available. I was able to estimate the altitude higher than 33,950.8 feet by comparing my atmosphere temperature model with many temperature models from institutions like NASA and the National weather service. Interestingly, my temperature model was very similar to their models. The highest altitude estimated by my temperature model was 147,637.7953 feet.
Astonished by this unbelievable result, I decided to confirm it with my onboard video record. The video had a time showing on the screen, so I was able to compare it with the telemetry data. The video confirmed that my balloon ascended above the ozone layer for sure and possibly reached higher than the stratopause, the level of the atmosphere which is the boundary between the stratosphere and the mesosphere. In the stratosphere the temperature increases with altitude, and the stratopause is the level where the temperature reaches the maximum. The world record of unmanned radio balloons is around 173,884 feet. Chollian X reached 147,637.7953 feet. It was not that bad.
Temperature vs Altitude model by ChollianX
Tempreature vs Altitude model by Weather Service
Temperature vs Altitude model by UWSP
Chollian X witnessed that the atmosphere temperature increases from 45,000feet to 112,733 feet, and then decrease from 112,733.1676 feet to higher altitude.
Pressure data analysis
I learned from Honors Physics course this year that pressure decreases as altitude increases. We could only learn this from a textbook and our basic knowledge because there was no way to experiment with this phenomenon in our class. Chollian X successfully accomplished this experiment. Ground level atmosphere pressure was 983 mb. At the maximum altitude, atmosphere pressure was 1.4313 mb. ChollianX ascended above 99% of the Earth’s atmosphere! If there were a tube connecting ChollianX at its maximum altitude and the ground level, the suction power would be the same as the power of vacuum cleaner because the internal pressure of vacuum cleaner is 1000mb lower than outside pressure. My uncle is senior A360 pilot in Korean Air. I was able to find answers for my questions about a commercial aircraft after interviewing him. Commercial jet aircrafts cruise between the altitudes of 35,000 feet and 44,000 feet. At this altitude the aircraft cabin pressure maintains 750mb which is the density altitude of 8,000 feet while the outside pressure is below 250mb. The rapid decompression of the cabin we see in many action movies is caused by the difference between two big pressures. If you suddenly open the aircraft door at 35,000 feet, the cabin pressure 750mb will try to reach equilibrium with the outside pressure 250mb, forcing the air mass in the cabin to exit.
Relationship between Pressure (in Mb) and Altitude (in Feet) by ChollianX
In Honors Physics, we studied the relationship between the pressure of a gas and its temperature (P1 / T1 = P2 / T2 ). This gas law was originally discovered by Gay-Lussac. He stated that the pressure of a gas sample is directly proportional to the Kelvin Temperature. ChollianX found that the gas law still applies to the atmospheric pressure and temperature model. The only exception was the molecule under 250 mb. The Oxygen-ozone cycle generates an ozone layer in this section of the stratosphere. The molecule in this section is warmed by having direct contact with UV radiation from the sun.
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| Blue ozone layer is visible from 85,000 feet or higher altitude. | Direct UV radiation from the sun causes Oxygen-ozone cycle |
Pressure and Temperature Relationship by ChollianX
Air density is directly related to sound. Sound is mechanical waves, and travels through vibrating the medium. The video record showed that when ChollianX reached around 100,000 feet the air density in the region was too thin for audible sound. In other definition, there is not enough medium in the upper atmosphere for sound to travel.
Part 4 Conclusion
My senior project greatly helped my understanding of the Earth’s atmosphere. Especially doing at actual experiment and then researching about the discovery were very helpful. I have learned how to inflate and to launch a weather balloon; how the ozone layer works; how the public has misunderstood ozone depletion; how meteorologist acquires weather information; and what is like to see the Earth from the near space. The result of the project was astonishing, especially the balloon video, so I accomplished most of the goals. The negative side of my senior project was budget. I overspent the budget because I have not done enough homework to know what I am supposed to be doing.
I would have to say how much I thank Holderness school for giving me such a great opportunity. It was the most exciting time of four years in Holderness.