|
|||||||
|
|
|
|||||
|
|
|||||||
PUFA NEWSLETTER
 |
||||||||||||
|
||||||||||||
|
|
November 18, 1998
Beverley Lawrence, President
Tobias Kreisz, Vice-President
Mario LeBel, Treasurer
Debbie Major, Secretary
Mail to: Pacific Ultralight Flying Association
102-16071 82 Avenue
Surrey, B.C. V3S 2L6
PUFA Newsletter published by Glenn Ursel
From The President
by Beverley Lawrence
At the last meeting, Gordon Brogan loaned a video of the last fifteen years of Ultralight flying and Ultralighter pilots to entertain the members. I was enthralled by the history of the images. Visions of a multitude of ultralights flying like a swarm of locusts into Abbotsford Airshow, the Surrey Air Festival where someone looped the loop in a Lazair. There were many memories of pilots now deceased and it prompted me to think that it is not the flying that is dangerous because, when I considered how these pilots died, only one was from an aircraft accident; the others were mainly from heart attacks and cancer. It was a reminder to take care of my diet and exercise, also to take time to enjoy the things most important to me before I can't.
I have been so busy lately that I decided to take a complete day off on November 11th; luckily the weather cooperated for long enough to take a flight. Not being restricted to terra firma, Fred and I were able to fly with James Sheremeta to Gibsons and moor at the marina for lunch at Grandma's pub. (I felt very much at home there having just become a grandmother for the fifth time). James is new to float flying, having spent some time rigging his Zenair with floats but he is really appreciating the freedom that floats give him and the many years of experience Fred is able to share with him. It was also sobering to reflect on Remembrance Day how fortunate we are to be able to enjoy the freedom of this beautiful country.
Don't forget to check your tiedowns as the winter winds have already started and the ground is getting softer. But enjoy the brief breaks in the weather as the dense winter air is great for flying.
Editorial Note
by Glenn Ursel
Since I haven’t received any ultralight stories from the membership this past month, I have again roamed the Internet for some aviation material to publish in the PUFA Newsletter.
The article about the use of a parachute to save the pilot’s life when his Cobra B ultralight failed in flight is almost enough to convince me to look into buying one although his description of the events leading up the incident would lead one to suspect he is not exactly a conservative flyer - “I was doing some yankin' and bankin' at about 500' AGL when the right wing buckled and bent back sending me into one incredible spiral.”
I included the article about the GPS for the possible interest of all those advanced ultralighters who seem to be buying these things these days. Wouldn’t mind getting one myself one of these days although Gord Denham says you don’t have to get the $1,000 fancy ones for our basic ultralights. All you need, he says, is a $250 one that enables you to measure your ground speed.
While I was drifting around the net looking for articles, I dropped in on Dave Loveman’s site and, lo and behold, I spotted Ken Hick’s old Hyperlight up for sale by Al Friesen who obviously must be cultivating the American market since he says he lives in “Creston, BC, Canada, just north of Idaho.”
Someone suggested I write profiles on each of our members in turn. I would like to try that with your kindly cooperation. I will be contacting members on this in due course.
December, 1998 Flying Events
Sunday, December 6, 1998, 9:00 am to 11:15 am
Delta Airpark, RAA Chapter 85 monthly pancake
breakfast
$3, 9:00 am to 11:15 am
Listen to the pre-recorded arrival procedures for Delta
Heritage Airpark
phone 878-9050
*Information supplied by Gordon Denham
Friday, December 11, 1998, 8 pm
PUFA Christmas Party
Will be at Marilyn and Terry Parsons again this year.
Structural Failure in Cobra, BRS Save - Pilot's Report
Tonight I was in my Cobra B ultralight enjoying the relatively calm cool air above Maryland. I was doing some yankin' and bankin' at about 500' AGL when the right wing buckled and bent back sending me into one incredible spiral. It took a couple seconds for me to realize that I wasn't going to come out of this spin and by then, several hundred feet of airspace closed between me and the ground. I heard the engine speed drop, or at least I THINK I heard it drop. I was looking straight down and saw the soy bean field getting closer and closer. Finally, I heard my instructor's voice in my head telling me to pull the chute. I was very disoriented due to the spinning and it was hard finding the chute handle. Fortunately, BRS paints them bright red. I looked down at it, saw it, and grabbed hold. I yanked as hard as I could and *POW* I heard the charge of the exploding rocket. I kept falling and the ground was VERY close by this time. I remember thinking to myself... "why hasn't the plane been flipped to a horizontal position because of the chute?" then all of a sudden, I felt the chute grab the air as I was jerked. I was only about 15 or 20 feet above the ground when it deployed.
The nose of the plane rammed into the ground and the plane seemed to collapse all around me. I was still suspended in my seat. I had on a seat belt and a shoulder harness that came across my chest. I unbuckled the harness and seat belt and dropped to the ground. Eventually, I found an opening big enough to crawl through. I got out as fast as I could so that the guys with whom I was flying would know that I was OK. I walked around surveying my plane.
I don't think there's a single piece of tubing that isn't bent or broken. Even the sails have tears in them where there is no reason to be torn. The plane is totaled. Even the prop blades are broken.
I got away with a couple knots on the old noodle, 2 cuts on the right side of my head, my glasses are bent, and I have one hell of a head-ache. I don't know what my head hit on. I don't remember feeling anything until after I crawled out from under the plane.
The chute didn't flip me horizontally because the heavy cable from the rocket to the chute lines got tangled in the tail section of the plane because of the spiralling. Kinda confirms the definition of "auguring in." All of us that fly UL's know that anything can happen at any time. It's part of the sport. I've thought a lot about what can happen while flying. When I got out of the plane I wasn't scared or nervous or shaken. I didn't have an adrenalin rush. I was concerned about my plane and the people I was with... I wanted them to know I was OK.
Lessons learned: 1. Be sure to have a rocket deployed parachute on your ultralight. You'd never believe how fast that ground comes up to meet your falling plane. If I would have had only a handdeployed chute I wouldn't be here to write this. (BTW, I have (had) a BRS soft pack chute which hasn't been repacked in probably 6 years - all right, that may be stupid, but it's the truth.) You all know that if I didn't have a chute at all, you'd probably be reading my obituary here instead of my account of the accident. GET A CHUTE IF YOU DON'T HAVE ONE.
2. Get a good 3 (minimum) or 4 point safety belt system. I'm guessing, but I’ll bet I would have sustained a lot more and more severe injuries if I would have been using only a lap belt. The shoulder harness saved my ass (along with the chute). Even when the plane hit the ground, I stayed securely fastened to my seat. I don't even have a bruise on my chest.
3. Get some instructions before flying. I can't believe that I actually heard my instructors voice in my head telling me to pull the chute, but I'm here. Flying without instruction is crazy.
4. Practice what you would do in an emergency. Like I said, I've done a lot of thinking about what to do in an emergency. I practice engine outs and dead-stick landings. I guess there's no way to prepare for what happened to me today, but do what you can to ensure your own safety.
So there you have it. I guess I'm the luckiest pilot in the world today. I was able to, literally, walk away from a 500 foot straight down spiralling fall. I guess I'll not be flying tomorrow. Damn! the weather is supposed to be perfect for ultralighting.
Originally published by Jon N. Stieger on his web page:
http://surf.to/ultralight-home-page
GPS - THE REMARKABLE GLOBAL POSITIONING SYSTEM
After writing an article on Global Positioning Systems (GPS) for Ultralights and small aircraft, I was asked how a GPS determines location speed and time. First a clarification of the use of the words Global Positioning System and the abbreviation GPS. I will use the written words Global Positioning System to mean the complete system of Satellites and Ground Stations. The abbreviation GPS will refer to earth based receivers that provides the user with location, speed, and time.
The basic principal seems simple enough, a ground based GPS calculates the time if takes for individual signals from at least 3 Satellites to reach a specific GPS receiver. The GPS multiplies the time interval to each satellite by the speed of light to obtain distance. The GPS then calculates it s location by triangulation. Speed and direction can also be obtained from a moving GPS. This is done from calculations of differences between successive locations over a given period of time. Time and date data is transmitted from satellites and decoded and displayed on your GPS. That is the basic concept, the amount of information processing and error correcting required to obtain any kind of position accuracy is mind boggling. In the following paragraphs I will try to explain: How the GPS knows the moving SVs location especially when SV position, with respect to time, on it s Earth track changes every day. How the GPS determines time (distance) between transmission and reception of a signal when the GPS clock has nowhere near the accuracy of SVs Clocks? If location accuracy is only 100 metres how the GPS determines velocity from time between two locations probably less than 100 metres apart?
The Global Positioning system was developed by the U.S. Department of Defence and is referred to as the Navigation Satellite Timing and Ranging Global Positioning System, or Navstar GPS. The Space Segment consists of Satellites referred to as Space Vehicles and abbreviated SVs. Each satellite is about the size and weight of a Cessna 182; it consists of solar power panels, 4 Atomic Clocks, communication and computing equipment and rechargeable batteries for eclipse periods. The GPS Constellation has 24 Satellites in 20200 Kilometres orbits rotating around the earth in 6 orbital planes. Each satellite tracks over the earth s surface at a velocity of 1800 Knots ( 2000 mph, or 3330 Km/hr.)completing one orbit every 12 hours. The orbits are configured such that each satellite repeats the same Earth Track once every 24 hrs.(actually 4 minutes less than 24 hours). Five to eight operational satellites are visible from any point on earth at any given time. The Standard Positioning System Accuracy (RMS) for Civilian users is 100 metres horizontally and 156 metres vertically. The Military is capable of obtaining 22 metre horizontal and 28 metre vertical accuracy. Random errors are introduced into the system to reduce Civilian use accuracy. It is not hard to imagine what a military adversary or terrorist could do with a GPS, computer, explosives and a bad attitude. Accuracy’s of 10 metres can be obtained with differential GPS. Differential GPS use, in addition to SVs, a ground based transmitter of know location for a reference. Similarly surveying accuracy’s of 1 millimetre can be achieved when two special use transmitters of known location and at least 30 km apart are used.
In answer to "How the GPS knows the exact SV location." -- The Global Position System consists of Space, Master Control, and GPS segments. The Global Positioning System Master Control Station is located at Falcon Air Force Base, Colorado Springs, Colorado. There are 4 monitoring stations throughout the world. One station is located in Hawaii and the rest are located as close as possible to the equator in the Mid Atlantic, just below India and North of New Zealand.
The master control and monitor stations control the satellite system. They track satellite location, process time, ephemeris and other data which is transmitted to the SVs. The SVs in turn transmit this data for GPS use. Each SV has its own identification, often referred to as it s PRN number. Predicted SV locations are referred to as ephemeris data. An ephemeris is a log of predicted sun and star locations with respect to time. Early sailors and explorers used ephemeris data along with a sextant to determine their location. Ephemeris in book form are available at most university bookstores. They are used today by surveyors, sailors and some pilots. Using ephemeris data and the exact time the GPS calculates its position using at least 3 SVs for position. If 4 SVs are available, altitude can also be determined. Each SV transmits bursts of position and time data. The GPS uses the position information in a preloaded algorithm to calculate and predict SV location with respect to time (ephemeris data). A GPS can reliably use this stored data for up to 4 hours. To verify SV time and location the GPS compares the SV data streams with its own data information. When these data bits match, the GPS "locks on" and accepts the location as being correct.
The GPS System operates on its own time system. Time is controlled by Atomic Clocks at Edwards Air Force Base, ground monitoring stations and space vehicles. Atomic clocks don’t run on atomic energy; they use the precise atomic oscillations of rubidium and cesium for accurate timekeeping. Four clocks per satellite ensure correct time is always available. The clock started January 5, 1980. Since GPS time does not make year end error corrections, (Leap Seconds) GPS time is now several seconds ahead of UCT (Zulu time). This is not of problem for GPS users as the system makes corrections that ensure the time displayed by your GPS is indeed UCT. Since the speed of light is 300,000 km. per second it takes only 6/100ths of a second for a signal from a satellite 18,000 km overhead to reach a ground based GPS; therefore time measurement is critical. Atomic clocks are accurate to one billionth of a second (.000000001 second).
When setting their own internal clock, ground based GPS units must account for the time it takes for a signal to get from the SV to the GPS. The accuracy of your GPS clock is nowhere near that of the $100,000 SVs Atomic Clocks. The inaccuracy between the SVs and GPS clock is automatically detected when the GPS calculates position. An analogy to determining location is to draw arcs of specific distance from 3 or 4 satellites. All of the arcs should cross at the same location. If they do not meet at the same location, a computer program in the GPS appropriately adds or subtracts distance (time) to each location and again checks to see if all distances meet at the same location. This process is repeated until a MATCH is made. Most GPS s continuously calculate and display the estimated probable error (EPE) due to these timing discrepancies.
Direction of movement is determined from changes in geographical position over time. Speed is calculated by dividing distance travelled over time and /or use the Doppler effect. The Doppler effect is the phase shift of signals or sounds received when a constant frequency source is moved away from or towards a receiver. An example of this is a loud Motorcycle travelling at constant speed past a pedestrian. The noticeable difference between the approaching and departing frequency is a result of the Doppler effect. The phase shift of a signal from or between moving objects can be measured. This phase shift is then used to calculate speed between objects.
Besides the US Global positioning system, a Russian system, Glonass is in position. The Glonass orbits are such that when one satellite goes below the horizon, another one rises at the same time. This and the fact that random errors are not introduced into the system makes for a simpler and more accurate system. It is expected that more accurate GPS units making use of both the US and Russian Satellites will soon be available.
I hope the above helped. It is written to explain the basics of the GPS system yet throw some light onto the complexity of the system. The text includes liberalization for the benefits of those of us that are not engineers surveyors or mathematicians. For example triangulation is not used to calculate location. Instead the cosine law and error correction of 3 calculated positions is used. Triangulation is imaginable for most, --using "The Cosine Law" in the above text would cause most readers to stop right there. Any comments questions or suggestions to improve this article are welcomed.
(By Ed D'Antoni ed.dantoni@bbs.logicnet.com)
Note: This article was contributed during November of 1996. The passing of time will no doubt render some of the information contained herein obsolete. Please bear this in mind.
Originally published by Jon N. Stieger on his web page:
http://surf.to/ultralight-home-page
For Sale: 1984 Sorrell Hyperlight - 447 Rotax low hours, 7 instruments, 11 gal tank, carb and/or cabin heat, brakes, trimtab. I am looking to buy a 2 place Sorrell. I have flown to Saskatoon and back over the Rockies. Over the Rockies 4 times once to Calgary and back. I live in Creston BC, Canada, just north of Idaho. Asking $9200.00 Can$ (about 40% less for U.S. customers) for this baby. Phone 250-428-8486 or email afriesen@kootenay.com.
For Sale: RX 550 Beaver, Rotax 447, New Stitts Fabric. Total time on
airframe 35 Hours. Health reasons force sale. A lovely aircraft sitting
at Qualicum Beach B.C. First $6000.00
Canadian will own it tcook@mail.bcsupernet.com
For Sale: 1988 Chinook IIS 2 seater, 503 Rotax SCSI, 350 TTSN 125 TTSMOH, skiis, electric start, excellent shape, great flyer, hangered,forced to sell $8,800 firm. Dated September 25, 1998 Mayerthorpe, Alberta, Canada bruclang@gyrd.ab.ca 403-786-4546
For Sale: 2 - 68 inch, 2 blade, ground adjustable, GSC wood props, Rotax tractor (left turning) - $150.00 ea. L'il Hustler@ultralightnews.com
Originally published by Dave Loveman at his website
http://www.ultralightnews.com/cfieds/4sale.html