On September 23rd and 24th we took Atlas out one more time to try to push the current endurance records and give the rest of the team members a chance to fly. Overall it was a great success with Trefor Evans setting a new world record at 86 seconds, Alexis Reichert setting a new women's world record at 53 seconds, and twelve new people added to the list of the few who have lifted off under their own power! Check out the flight videos at youtu.be/LGBtdSdCUw0and youtu.be/MfR85XTzeQc.
Going into the flight tests, our goal was to set new men's and women's records and to truly demonstrate what Atlas was capable of. Our in-flight power measurements show that for an 160 lbs pilot, somewhere between 410 and 440 Watts is required to maintain a low hover. In peak form, Todd's best power test resulted in 430 Watts for 5 min 53 seconds, so we knew that flights in the range of 5 minutes where possible. However, we had never pushed for endurance before, and as with anything of this nature we anticipated that there would be unforeseen problems.
The first issue to overcome was that of the drive line length. The drive lines spool from the rotor onto a hoop around the cranks, and there's only about 85-90 seconds worth of line before you run out. Since we weren't going for any more high altitude flights (which required over 1100 Watts during the AHS Sikorsky Prize flight), we switched to thinner drive lines. Thinner lines don't take up as much room when they stack on the spool (see photo below), which meant we could use longer lines and extend our flight time to roughly 4 min 30 seconds.
On the first day, before switching to thinner lines, we wanted to make sure we secured the endurance records. Trefor Evans did all of the trim flights, and then took a break for Alexis' record attempt. Alexis was one of the original team members that helped build Atlas during the summer of 2012, and coincidentally Todd's little sister (hence the genetically abnormally sized quads). Alexis is an avid biker with a strong athletic background in rowing and rugby. Alexis got one practice run with a 10 second flight before warming up for a record attempt. Blasting past the previous record of 11.4 seconds, Alexis was called down as she approached the rear wall at 47 seconds. A smooth flight and a new world record!
Next Trefor jumped back on and pounded out a 73 second flight (just shy of the record) that was called down because he was drifting too close to the wall. Trefor was also one of the original Atlas team members, responsible for the design optimization of the truss structure, and one of the two trim pilots throughout the testing of Atlas. Coincidentally Trefor also has a background in rowing and rugby (actually, so does Todd) and is a strong cyclist. After small adjustments he pushed to 83 seconds, setting a new endurance record before being called down because the drive line had nearly run out.
By the end of the first day, we had seen what Atlas could do with the short drive lines, and now it was time to up our game. Given the nature of this beast, it was not surprising that we ran into a few issues. With Calvin Moes at the helm we started to fine tune the trimming, but it proved to be quite difficult. It seemed as though the thinner drive line (being much more flexible) would amplify imbalances in the rotors, and after a certain amount of time the rotors would be dangerously close to striking the bracing lines. At the same time we noticed a multitude of cracks in the drive spools. Since the line is being spooled on under tension, each new wrap on the drive spool adds an additional structural load. With many flights in the 1 minute range, the spools were showing some serious damage. We decided that to be safe we wouldn't exceed 2 minutes 30 seconds, and that we would stick with the lighter pilots. Todd wasn't as light as when he was dieting for the AHS Sikorsky Prize, and both Calvin and Trefor were likely both capable of reaching our newly defined limit of 2 min 30 sec. So with Calvin on board we attempted to further the endurance record once more.
Calvin is also one of the original team members, responsible for the rotor spools and the incredible carbon-fibre work around the drive spools. Calvin has an incredibly diverse background and is a strong overall athlete. On the record attempt he held strong to 57 seconds, but was called down because of the rotor imbalances where getting too large. Although the problem of the cracks in the drive spool and the imbalances in the rotor could be figured out given enough time, we decided not to push fate and to switch over to our second goal: to fly as many team members as we possibly could!
Before September 24th there had been more people that had walked on the surface of the moon than people that had flown a human-powered helicopter. Now this is distinctly not the case 😉 A huge congratulations to the twelve new pilots who all earned their flight time with their hard work, passion and dedication to the Atlas team! First up was Alexis, who managed to push her previous day's world record to an incredible 53 seconds! After that we cycled through the rest of the team, with pretty much everyone taking off without a problem including 52 year old Professor Jun Nogami, 55 year old retired Sikorsky VP Marc Poland, and 15 year of Davy Evans (Trefor's younger brother). Finally, at the end of a great day, Marc Jutras took off, loaded with a few cans of Molson Canadian, for our entry in the HobbyKing Multi-Rotor Beer Lift Competition! Great work everyone! Tonnes of fun 😉