Thanks Jure, a really interesting video on the history of F5J. It took me back to my early days of soaring, initially competing in F3B. Around 1975 (still in primary school) after reading some articles by Fred Militky I converted an Airtronics Olympic glider to electric launch. Using a home rewound brushed motor with a homebrew gearbox and propellor it launched and flew quite well. The limiting factor was how long it took to recharge the NiCad battery pack, around and hour. As a schoolboy I could only afford one battery pack build up from AA batteries "liberated" from other devices. We have come a long way but what a ride! Thanks for the trip down memory lane!
It was great to see the references to Frank Zaic in your video. When I was in US high school, we had an aviation club. The club had a year long competition, and the winner won a lunch with Frank Zaic (1978). Turned out that he lived only a few miles from where I went to school. Sadly, I was too young to recognize this rather high honor. Interestingly, I met up with him and his wife about a decade later, when the NAA presented him with a lifetime achievement award. I was at the NAA meeting to receive an award as well due to my setting the F3B #25 world record (declared distance to a goal, which was an rc glider flight of 266 km point to point). What was great was that by happenstance, Frank and I ended up sitting next to each other in the audience. By that time, I recognized my amazing luck to have met him, and more than once. I have been so fortunate, in so many ways.
A big problem in popularising the sport is that almost all, if not all, F5J competition models are composite and generally professionally "factory" built, and therefore expensive. Some people make their own, but that requires a good airy workshop which to modern apartment dwellers is inaccessible. I suggest that you look at the development of the F3-RES (FAI F3L) class of two-metre glider launched using a rubber hi-start ("bungee"). The F3L rules specify largely built-up wooden wings, tail surfaces and forward fuselages (the boom and spars can be composite and are inexpensive and widely available). This makes for a much less expensive model. There is also an RE built-up glider class in Czechia, of less restricted size, oriented toward beginners and youth. I wonder whether something similar may be a good idea for electric powered gliders. The built-up designs of Mark Drela are a good beginning point; the F3L gliders are similar to his 2-metre Allegro Lite, and his 3-metre Bubble Dancer glider is in the F3J class, easily adapted to F5J. While Drela's very strong high performance winch-launched gliders date from circa 2000, his aerodynamic ideas and airfoils have been dominant in model glider design since then, with manufacturers building lighter and more slippery models over the years. Incidentally, the F3J glider class was established after the 1981 F3B World Championships in California, when composite designs were taking over and the Canadians terrified everybody with Kevlar models launched with 36-volt winches (I flew wih them when they were training in Victoria, BC). Not only was the F3B rulebook rewritten, but F3J was set up as a more sedate thermal duration class, launched by human towline power instead of ferocious winches. Somehow that quickly translated to an even more powerful launch than winches, and the composites took over, displacing the gentle floaters of the 1970's that no doubt everybody was thinking of when setting up F3J. The F3L class avoids the expense spiral that all the other classes have suffered, though balsa kits are not exactly cheap these days.
My dad nearly made the US World Team in 1980/1981. He started by flying the long thin winged gliders of the 1960s and then build a Sailaire (sp). he found the tail would catch on the grass. He built a tail cone to protect the rudder. He liked to "kite" the sailaire when launching from a winch or hi-start so he developed a toe hook that could hold the line and then release it. At the NATS they gave him an award for best technological innovation (it was also the year my mom was pregnant with my brother - much joking happened around that). He was on a first name basis with Dan Pruss, who was instrumental in the US with the NATS and The Great Race. He and Dan as well as a few other guy rode in Dan's van to contests around the midwest. Stories were made that our now legends. When I came along in 1973, i was named after Dan Pruss. I can remember going to the flying field and seeing guys gather around a plane, listing to the flyer talk about this improvement and that - or stand around a wreckage discussing what led to the crash. My dad saw the limitations of the Sailaire - it was slow and couldn't penetrate the air to search for lift. I can't imagine how it would fly on a windy day - add more ballast? He found the Viking II to be the future - his answer to the TD 10 minute Task. He built two or three sets of wings for it - a flat bottom for light days and a semi-symmetrical for windier days (I probably have that wrong). He built in a release-able toe hook - then mass produced. With the Viking II flying stab elevator design it was like the Sailiare - it could make a tight circle for thermalling and maneuvering. He added a automotive engine belt to the nose to grip the ground for quick stop landings. He practicing his 10-minute flights and had me countdown the watch as he made timed circles near the landing area. All of this was in preparation for the US Team. He finished just outside of the team. Family took more time and he spent less time in the hobby until we all moved out of the house as adults. Once the hobby was one of building and testing your build. It was one of personal innovation. The highs were heroic and the lows meant it was back to the basement shop to fix, rebuild or build anew. On powered plane fields - the smell of hobby gas fuel came from trash cans which collected the crashed parts of broken dreams - to return to the field or never to return again. My dad's Viking II disintegrated on a demo speed pass. I remember seeing the plane come apart and spiral into the ground. He found it was a bad glue joint on the spar (I think). He went home and fixed the issue - never to happen again. He added a composite spar - a sandwich of carbonfiber and foam to later spar designs. These days - he flies an Ava Pro - beat up like a NASCAR car after 200 laps - but he wings contests with it. (I finished last year in 2nd or 3rd place with it www.mvsaclub.com). He flew a composite plane programmed by Chris Lee ( a young, now retired from R/C Soaring) engineer minding man who helped bring the club into the current era. We have contests and enjoy flying but the barrier to entry is pretty high as well as the learning curve and risk to learn, crash and try to fix a modern glider. Instead of talking about design and build they (I try not to) talk about a dominant design as if it were the new name for "glider". We fly beat up and repaired carbon fiber gliders - old by today's standards - against $4000 pre-made gliders from the best aerospace designers around the world. We do live in a new time but what can we do to bring back the scrappy world of "let me fly your plane - you have a warp - you need more wash in or wash out - come over to my house and I'll help you fix it with my heat gun - and then we'll fly in the contest next week" world? I don't know? We also don't fly in public parks - we fly on private fields - people don't accidentally stop by and want to learn more - nor do we reach out to them. (Sipping my working coffee - typing out this "article" on TH-cam - bemoning a past I had issues with but now seeing it was a golden era - get off my lawn - I'm getting older.) Now I'm our club's webmaster - and this question is on my heart - when I care - and not on my heart when I give up and fly my beautiful Xplorer 3 - repaired with epoxy by my dad. (I need to pain over the scars) My dad's basement is filled with balsa gliders containing address labels of his friend who passed away - a museum.
Enjoyed your discussion 👍 and thanks for the videos you record and upload each year - I know it's a lot of effort. Developments in electric power for RC gliders combined with composite construction methods has opened up thermal flying for so many of us. Even though I don't (or can't) compete I'm someone who very much gets pleasure from soaring like the birds. The Aptera looks very interesting...
Thanks Jure, a really interesting video on the history of F5J. It took me back to my early days of soaring, initially competing in F3B. Around 1975 (still in primary school) after reading some articles by Fred Militky I converted an Airtronics Olympic glider to electric launch. Using a home rewound brushed motor with a homebrew gearbox and propellor it launched and flew quite well. The limiting factor was how long it took to recharge the NiCad battery pack, around and hour. As a schoolboy I could only afford one battery pack build up from AA batteries "liberated" from other devices.
We have come a long way but what a ride! Thanks for the trip down memory lane!
It was great to see the references to Frank Zaic in your video. When I was in US high school, we had an aviation club. The club had a year long competition, and the winner won a lunch with Frank Zaic (1978). Turned out that he lived only a few miles from where I went to school. Sadly, I was too young to recognize this rather high honor. Interestingly, I met up with him and his wife about a decade later, when the NAA presented him with a lifetime achievement award. I was at the NAA meeting to receive an award as well due to my setting the F3B #25 world record (declared distance to a goal, which was an rc glider flight of 266 km point to point). What was great was that by happenstance, Frank and I ended up sitting next to each other in the audience. By that time, I recognized my amazing luck to have met him, and more than once. I have been so fortunate, in so many ways.
A big problem in popularising the sport is that almost all, if not all, F5J competition models are composite and generally professionally "factory" built, and therefore expensive. Some people make their own, but that requires a good airy workshop which to modern apartment dwellers is inaccessible. I suggest that you look at the development of the F3-RES (FAI F3L) class of two-metre glider launched using a rubber hi-start ("bungee"). The F3L rules specify largely built-up wooden wings, tail surfaces and forward fuselages (the boom and spars can be composite and are inexpensive and widely available). This makes for a much less expensive model. There is also an RE built-up glider class in Czechia, of less restricted size, oriented toward beginners and youth.
I wonder whether something similar may be a good idea for electric powered gliders. The built-up designs of Mark Drela are a good beginning point; the F3L gliders are similar to his 2-metre Allegro Lite, and his 3-metre Bubble Dancer glider is in the F3J class, easily adapted to F5J. While Drela's very strong high performance winch-launched gliders date from circa 2000, his aerodynamic ideas and airfoils have been dominant in model glider design since then, with manufacturers building lighter and more slippery models over the years.
Incidentally, the F3J glider class was established after the 1981 F3B World Championships in California, when composite designs were taking over and the Canadians terrified everybody with Kevlar models launched with 36-volt winches (I flew wih them when they were training in Victoria, BC). Not only was the F3B rulebook rewritten, but F3J was set up as a more sedate thermal duration class, launched by human towline power instead of ferocious winches. Somehow that quickly translated to an even more powerful launch than winches, and the composites took over, displacing the gentle floaters of the 1970's that no doubt everybody was thinking of when setting up F3J. The F3L class avoids the expense spiral that all the other classes have suffered, though balsa kits are not exactly cheap these days.
My dad nearly made the US World Team in 1980/1981. He started by flying the long thin winged gliders of the 1960s and then build a Sailaire (sp). he found the tail would catch on the grass. He built a tail cone to protect the rudder. He liked to "kite" the sailaire when launching from a winch or hi-start so he developed a toe hook that could hold the line and then release it. At the NATS they gave him an award for best technological innovation (it was also the year my mom was pregnant with my brother - much joking happened around that). He was on a first name basis with Dan Pruss, who was instrumental in the US with the NATS and The Great Race. He and Dan as well as a few other guy rode in Dan's van to contests around the midwest. Stories were made that our now legends. When I came along in 1973, i was named after Dan Pruss. I can remember going to the flying field and seeing guys gather around a plane, listing to the flyer talk about this improvement and that - or stand around a wreckage discussing what led to the crash. My dad saw the limitations of the Sailaire - it was slow and couldn't penetrate the air to search for lift. I can't imagine how it would fly on a windy day - add more ballast? He found the Viking II to be the future - his answer to the TD 10 minute Task. He built two or three sets of wings for it - a flat bottom for light days and a semi-symmetrical for windier days (I probably have that wrong). He built in a release-able toe hook - then mass produced. With the Viking II flying stab elevator design it was like the Sailiare - it could make a tight circle for thermalling and maneuvering. He added a automotive engine belt to the nose to grip the ground for quick stop landings. He practicing his 10-minute flights and had me countdown the watch as he made timed circles near the landing area. All of this was in preparation for the US Team. He finished just outside of the team. Family took more time and he spent less time in the hobby until we all moved out of the house as adults. Once the hobby was one of building and testing your build. It was one of personal innovation. The highs were heroic and the lows meant it was back to the basement shop to fix, rebuild or build anew. On powered plane fields - the smell of hobby gas fuel came from trash cans which collected the crashed parts of broken dreams - to return to the field or never to return again. My dad's Viking II disintegrated on a demo speed pass. I remember seeing the plane come apart and spiral into the ground. He found it was a bad glue joint on the spar (I think). He went home and fixed the issue - never to happen again. He added a composite spar - a sandwich of carbonfiber and foam to later spar designs. These days - he flies an Ava Pro - beat up like a NASCAR car after 200 laps - but he wings contests with it. (I finished last year in 2nd or 3rd place with it www.mvsaclub.com). He flew a composite plane programmed by Chris Lee ( a young, now retired from R/C Soaring) engineer minding man who helped bring the club into the current era. We have contests and enjoy flying but the barrier to entry is pretty high as well as the learning curve and risk to learn, crash and try to fix a modern glider. Instead of talking about design and build they (I try not to) talk about a dominant design as if it were the new name for "glider". We fly beat up and repaired carbon fiber gliders - old by today's standards - against $4000 pre-made gliders from the best aerospace designers around the world. We do live in a new time but what can we do to bring back the scrappy world of "let me fly your plane - you have a warp - you need more wash in or wash out - come over to my house and I'll help you fix it with my heat gun - and then we'll fly in the contest next week" world? I don't know? We also don't fly in public parks - we fly on private fields - people don't accidentally stop by and want to learn more - nor do we reach out to them. (Sipping my working coffee - typing out this "article" on TH-cam - bemoning a past I had issues with but now seeing it was a golden era - get off my lawn - I'm getting older.) Now I'm our club's webmaster - and this question is on my heart - when I care - and not on my heart when I give up and fly my beautiful Xplorer 3 - repaired with epoxy by my dad. (I need to pain over the scars) My dad's basement is filled with balsa gliders containing address labels of his friend who passed away - a museum.
Enjoyed your discussion 👍 and thanks for the videos you record and upload each year - I know it's a lot of effort.
Developments in electric power for RC gliders combined with composite construction methods has opened up thermal flying for so many of us. Even though I don't (or can't) compete I'm someone who very much gets pleasure from soaring like the birds.
The Aptera looks very interesting...