Embedded Files
Recap Video From our Spring 2016 Project
Guiness Book of World Record Attempt, "Highest Paper Airplane Launch"
Launch Date : Monday, May 23, 2016
Launch Time : 10:00am central Time, 15:00UTC
Launch Location : Spring Grove Elementary School
Google APRS tracking : KC9YMN-11 position report every 61 seconds
Video Stream available on 1.3ghz, KC9YMN
Release point from 3000g weather balloon : 36,500 m, or 119750 ft above sea level
need to beat 35,043 m or 114,970ft
Ascent time to 36,500 m : about 150 minutes
Descent time from 36,500 m : about 75 minutes
Predicted furthest distance away from launch : 19.2km
Paper Airplane Weight : 1500g
Neck Lift : 2397g
Project Update 05/24/2016, post flight analysis.
Well we did not break the record.
Northwest Herald Article
Telemetry data
Flight data
FIrst APRS time stamp was at 1469ft at 10:17 central time
Our maximum reported altitude was ... 113,411ft at 14:19 central time
Time to climb from 1469ft to 113,411ft was 242 minutes
Total altitude gain during the 242 minute climb out ... 111,942ft
Average climb rate .... 462.5ft/min, 140.8m/min, or 2.3m/sec
Planned climb rate .... 783ft per minute, 238m/minute, or 3.9m/sec
Power supply info
12volt, 2200 milli amp hour battery (mAh)
The 12v battery powers the Vector OSD
The vector OSD powers the camera, the OSD info, the transmitter, the dragonlink Tx and the nichrome wire for the paper airplane release.
Kept the battery warm with a single hand warmer, packed next to the battery.
See pictures below
current draw when power up .... .4 to .5mAh
with this arrangement we had about 4 hours and 24 minutes worth of power
2.2amps / .5 ampH = 4.4hours of available power
We power the system up at approximately 9:45 am, so 30 minutes of power was used on the ground prior to launch, that left us with approximately 4 hours of battery power for the flight.
Our power supply was exhausted at approximately the same time we reached our maximum altitude...at 14:15 central time. Battery voltage was observed to go below 9v. We lost the visual transmission at that time. The aprs tracker was still capable of operating for a few more minutes. The APRS tracker would operate down to 3.0v or so.
(See lipo discharge curve below, note this is for a single 3.7v cell, we had a 3 cell 12 volt lipo battery). The discharge curve is the same for all Lipo batteries.
Weather balloon and helium data
Weather balloon ... Kaymont 3000g balloon
Payload weight (paper airplane) ... 1500g
Positive buoyancy used ... 720g (extra lift)
280g worth of fill hose and fill tube
Milk jug calculations using the burst calculator
The burst calculator calculated a Neck Lift (milk Jug Weight) of
2397g rounded up to 2400g
I subtracted the weight of the fill hose and fill tube (280g)
now I came up with 2120g milk jug weight, I then added 100g back in just for a little extra to offset tape, zip tie, and the carabiner clips, for a total neck lift (milk jug weight of 2220g)
Time to climb from burst calculator = 163 minutes
Total ascent altitude from calculator = 38750m or 127,750ft
(I used a much higher number than our planned release altitude, to ensure we would make 119,750ft)
Rate of climb calculated from the burst calculator = 127,750ft/163min = 783ft/minute
So where did we go wrong in our planned amount of helium.
We only climbed at a rate of 462ft/min, when we needed to climb out at 783ft/min
My thoughts.
I think we needed to use more helium. I think we came up short for the following reasons.
Ground temperature was in the lower 70's at launch time, the sun was shining very brightly under clear skies. One contributor to the problem was the thermals coming off the ground. The ground was in the process of warming up rapidly that morning. The large mass area of the inflated balloon near the surface was enabling the balloon to ride those thermals. I am guessing that the amount of thermal lift we were receiving was maybe 200 to 300 grams worth of helium lift. When i have time I will calculate the early stages of climb out versus the later stages of climb out. I think that will help determine if thermals contributed to our problem of not using enough helium. If early (low altitude) climb out rates were greater than late stage (higher altitude) climb outs, then I would suspect that our balloon was susceptible to thermals near the ground leading to miscalculation of the total lift being generated by the balloon when offset by the milk jug.
Winds at the launch location may have contributed as well. Winds were gusty at he time of the fill and launch (estimated gust of 12 to 15mph out of the south). We tried to get accurate lift information by making sure the balloon had just enough lift to cause the milk jug to rise just slightly off the ground. We waited to get measurements when the winds were light. That little bit of wind blowing on the inflated balloon could also have contributed to a small 100g to 200g worth of helium lift.
Reverse engineering of the burst calculator.
So if I place our actual average climb rate into the burst calculator, you can see that the neck lift is now 1776g. our actual neck lift was 2220g. That is a difference of 444g of helium lift. How did we end up 444g worth of helium short? Well when we take into account the wind and thermal lift we could easily account for the 444g difference in required lift. Now observing the data one would point out that based on the reduced amount of helium, that we should have made 39886 meters until burst. That is true from the burst calculator above. But the burst calculator (to the best of my knowledge) does not account for the total amount of helium loss during the climb out. The helium atom is so small that it is able to gradually slip through the latex fabric at a metered rate. That is why weather balloons have the potential to become a floater. A "floater" happens because not enough helium is used to reach a targeted altitude. At ground level you will witness a climb rate, but as the weather balloon looses helium during the ascent, the slow metered leak of helium through the latex balloon will begin to slow the climb rate. The climb rate will decrease to the point that there is no longer enough helium to offset the payload. The balloon and payload with no longer climb or descent. They will simply float. Now as more time goes by and the helium continues its metered leak, the balloon will eventually descend back toward earth. Floaters are dangerous because of the risk that they pose to air traffic.
Our balloon became a floater in the 112,000ft range. As the balloon lingered at this altitude, the latex was severely degraded due to radiation exposure. It was only a matter of time until the latex would become compromised, and the balloon would burst, which it did at approximately 113,500ft
Other Flight Problems
The Vector OSD
The first recognizable problem was the GPS altitude readout from the Vector OSD.
The readout would only correctly display until 21,500ft. At 21,500ft the GPS would reset to 0ft. Every 21,500ft, the GPS altitude would reset. I will contact Eagle Tree systems to see if we can address this problem for our Spaceport Flights. I had the paper airplane set to read out Barometric altitude. I need to contact Eagle Tree systems and see if there is aa way to address these issues. The best way would be for all altitudes to read above sea level or absolute GPS altitudes. We also need them to address the reset points so that the info does not reset on us.
The next screen shot is just after passing 21,500ft
Bill Browns (wb8elk) APRS tracker
Worked perfectly, Sent a reliable APRS signal every 61 seconds.
The only problem, but this was known, was that we did not get temperature info. Bill just built this new tracker, and he was developing the Temp probe for it. Other than that, the tracker worked perfectly. It was powered by the Dragonlink receiver. using power (5V) from receiver channel number 8. Even after our string broke on the left side of the paper airplane, it still continued to work perfectly. (The dipole antenna was now parallel to the ground verse perpendicular to the ground). All ground antennas (APRS digi peaters are oriented perpendicular to the ground, so the sending antenna should be perpendicular as well). The antenna being sideways (parallel to the earth) did not affect any signals at all.
Conclusion...is it really important for dipole antennas to be oriented perpendicular to the ground? Thoughts Alex, Mike or Bill?
Dragonlink Tx and Dragonlink Receiver
This is the repeater station. The kids use the Spectrum transmitter in the classroom, the transmitter sends it signal to the lemon receiver at the repeater box located outside on the school roof. The lemon receiver then sends the ppm stream to the Dragonlink Tx. The Dragonlink Tx then send its signal to the Dragonlink receiver in the paper airplane.
The reason for the repeater box is so the kids can use the remote control in the classroom with out having to be outside with the transmitter.
Worked perfectly as always. Thank you Mike for your continued development of the dragonlink products. We used the stock dragon link antennas and the DL tx was set to "High" for the whole flight. DL Tx was power by a 12v 2650mAh battery, the battery was fully charged before flight. 12.5volts or so. After 5 hours of operation the DL battery was still at 11.8 volts, plenty of power was left.
Maximum ground track distance from the school 14.4 miles
At 14.4 miles away we were at 79,000ft (15 miles above the ground)
Slant range line of sight distance = 20.76miles.
RSSI at 20.76 miles = 10% to 33% (Dipole parallel to earth). This was even with the dipole antenna tilted parallel to the earth. The orientation of the dipole did not seem to bother the RSSI much.
The first pass near the school occurred at a ground distance of 1.7miles wnw of the school at 33,000ft, RSSI = 18% to 22% at that time (dipole perpendicular to the earth).
The second near pass of the school occured at a ground distance of 1.6miles wsw of the school at 113,000ft, RSSI = 17% to 20% at that time (Dipole parallel to the earths surface at that time.
Conclusion.
Dragon link performed perfectly again. Even though we ran out of main power and were thus never able to release from the balloon, the DL maintained communication with the Dragon link Tx through out the entire flight. We may want to upgrade our Ground based antenna to a yaggi antenna for our Spaceport project.
See the same information above in the Bill Browm tracker. All the same theories apply.
Video Equipment and Video Aerial Systems antennas.
Worked as well as to be expected. Typical problems associated with having the directional antennas pointed at the Tx antenna (Mad Mushroom) on the paper airplane. Ground based antennas used.
Gatling 1.3ghz antenna
Pepper Box 1.3ghz antenna
Mad mushroom 1.3 ghz antenna
Eagle tree diversity antenna, used the pepper box and the gatling to feed the pepperbox.
We never lost video signal through our the flight. We may have had issues with the 1watt video transmitted overheating. The overheating was caused by solar radiation and the inability to cool while climbing at the higher altitudes.
Alex I will upload the full video for you to scrutinize. You are the expert when it comes to Video systems.
(Future YouTube link to captured video)
Conclusion
It is my conclusion that we did not make the projected altitude because we did not inflate the weather balloon with enough helium. Thermal lift and winds at the surface could have accounted for the 400-500grams worth of lift shortfall in our calculations, hence the reason we did not make our 119,750ft planned altitude.
The local weather conditions
This is a screen shot of the predicted flight path.
The 5th grade students of Spring Grove Elementary are going to try and break
the worlds record for the
"Highest Paper Airplane Launch"
This is no easy accomplishment. The record was held by the students of Albert Athens Elementary School of Glen Carbon, IL.
That record was lost to a group of students from the UK.
The current record is 35,043 meters or 114,970 ft.
The students of Spring Grove Elementary will shoot for 36,000 meters or 118,000 ft.
This is not going to be an easy task, but we will give it our all to bring home the record.
5m meeting dates...
April 12 at 1:20 until 2:20 (Scale up paper airplane onto cardboard)
April 25 at 9:00 until 10:00 (4th meeting, go over homework, chapter 2,3 in workbook, weather, winds aloft, prediction web-site)
Project Enterprise
Launch and Tracking teams
5k meeting dates
April 13 at 9:00 until 10:00 (Scale up paper airplane onto cardboard)
April 27 at 9:30 until 10:30 (4th meeting, go over homework, chapter 2,3 in workbook, weather, winds aloft, prediction web-site)
Project Skyfall
Camera and Balloon
5c meeting dates
April 18 at 9:00 until 10:00 (Test Paper Airplane designs)
April 21 at 9:30 until 10:30 (Scale up paper airplane onto cardboard, and test fly)
May 5th at 9:30 until 10:30 (4th meeting, go over homework, chapter 2,3 in workbook, weather, winds aloft, prediction web-site)
Project "Star Struck"
Paper Airplane Team and Payload Specialist teams
Google Sites
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