Hi Everyone,
This week we performed another day of testing at the Soccer Centre with the Atlas Human-Powered Helicopter. We conducted five flights overall. The first three were to trim the rotors without canards, balancing each blade and equalizing lift. The final two flights were to balance the rotors with the control canards installed, with the final flight including a control effectiveness test. In the continued lead-up and preparation for an attempt on the AHS Sikorsky Prize, we had two main objectives:
1) Could we sufficiently stiffen up the truss structure to limit the progress of or eliminate small trim imbalances through the flight;
2) Could rotor blade balance be maintained during control actuation, and do the controls have sufficient authority.
We were able to address each these questions with a definitive “Yes”. For the first question, the team carried out progressive tensioning of the truss bracing lines between tests, and by the end of the day the structure was roughly twice as stiff as before. At this point we saw no observable progression of trim imbalances, quite a change!
A screencapture from Gamma rotor's camera during the 5th flight on January 18th, 2013.
As for the second question, we observed that actuation did no disrupt blade balance, and also that the controls are very effective. We've posted a video of Friday's final flight on the AeroVelo YouTube channel. The helicopter was airborne for 22 seconds, and you can see evidence of Atlas's control effectiveness in action. Around 10 seconds into the flight, Todd actuated the controls by about 50% to induce a deliberate forward drift. The results are obvious a few seconds later, when the front rotor (alpha) drops to the ground and the rear rotor (gamma) gains about 2 feet in height. Pretty dramatic!
Briefly, the average power during the day's flights ranged from 435W (during the first trim flight with no canards) to 600W (during the day's last flight, a problem with the drive train is suspected). As we've began to observe, power numbers during optimal flights with and without canards have agreed very well with our predictions, at times (e.g. 435W) being even less than expected. More to come on this during a post later in the week.
We would also like to congratulate Calvin Moes on becoming the team's 2nd pilot, after he flew the helicopter during flight #2 for around 10 seconds. We have began to include additional pilots to conduct trim flights in order to provide some relief for Todd, reducing the rate at which he fatigues on long testing days. Calvin did an excellent job and demonstrated his nerves of steel.
On our agenda for this week:
1) Make any small repairs necessary to Atlas;
2) Improve and clean up the drivetrain to resolve Friday's outstanding concerns;
3) Finalize stiffening up the truss and tensioning all bracing lines;
On January 25th we will be making an attempt at a Sikorsky Prize flight! We feel that with many of the improvements to-date and the few incremental steps remaining we will be ready to make prize-flight attempts in the early afternoon. All are welcome to come watch the day's testing, from 9am-5pm at the Ontario Soccer Centre in Vaughan.