 |
| Craig Robinson pilots DaSH during his 1 km long flight |
Craig's 1 km flight filmed from Chase Bike
On the weekend of February 21st & 22nd, we had our second test flight weekend, and it was a great success.
We entered the weekend with a few main goals:
- Verify that our fix to the vertical tail mount worked
- Verify that changes to the tail surface slew rates improved handling
- Test that our fixes to prevent the chain from falling off worked
- Get successful readings from the powermeter and the new airspeed sensor
- Have successful flights with as many new pilots as possible
We came out of the weekend meeting all those goals and more. We had myself and 5 other pilots available and ready to fly. In our best case scenario, we thought that 2 or 3 people each day might get a chance to fly, and there would be just an outside chance for all pilots to get a flight in on the weekend. In the event, only I flew the first day before weather conditions and the condition of the airplane stopped flying for Day 1, but on Day 2, all 5 of the remaining pilots got a chance to fly, with most flights of significant distance and duration. The longest flight was just under 1 km (994 meters) and 2 minutes 24 seconds duration, only ending because we were running out of runway on which to fly.
This bodes very well for our future flights, that we hope to be of longer distance and duration. And having 5 brand new pilots do so well in their first flights speaks well of the handling qualities of the airplane.
Here are some photos from the day, followed by short descriptions of the flights from Day 1 (Feb 20) and Day 2 (Feb 21), with videos of most flights.
 |
| Assembling the airplane before dawn |
 |
| Greg Thomas flies DaSH (453 m flight) |
 |
| Craig Robinson flies DaSH |
 |
| Craig Robinson taken from Chase Bike |
 |
| Geoff Bower flies DaSH |
 |
| Closeup of DaSH flying |
 |
| Wheeling DaSH out to the runway |
 |
| Ginger Kroft after her successful flight |
 |
| Alec Proudfoot preparing for flight |
Day 1
On Day 1, I was slated to fly to plane first, the main goals to be making sure our tail mount fix worked and that handling was improved given our adjusted tail slew rate settings. We also wanted to make sure our chain guide fixes prevented the chain from popping off as frequently as it did back in December, and we also wanted to make sure the airspeed indicator and power meters worked.
I was somewhat out of shape, and had been suffering from a cold, so I wasn't in as good of a condition to pilot as I was during our first flight back in December. We also had more challenging conditions, a right 45 degree crosswind from 3 to 6 kph (compared to 3 kph straight down the runway back in December).
However, the first flight went pretty well, albeit a somewhat short one at 125 m and 18 seconds. We didn't realize it at the time, but I landed a bit sideways due to the crosswind, and that damaged the main landing gear wheel somewhat.
My second flight was longer, 178 meters and 26 seconds. The takeoff run was long because of the bumpy main landing gear (which we still hadn't discovered), and I just ran out of gas at the end of the flight. Geoff later determined that flying in the runway 30 'uphill' direction is roughly 50 Watts extra effort compared to flying level (depending on pilot weight), so that, added to my poor physical condition made a longer flight problematic.
But I was very happy with the performance of the plane. It handled great, the tail mount fix obviously worked, and the chain was staying on. The airspeed indicator had worked pre-flight, but an auto-shutoff feature prevented us from getting reliable airspeed data from our new sensor (the old, less reliable sensor was still working and recording data). A software fix by Rodrigo overnight cured the auto-shutoff problem for the next day.
We were going to do more flights, and get more pilots going, but three things happened almost at the same time: - the crosswind picked up to 10 to 12 kph, right at the limit if it was down the runway but probably too much for a crosswind, a support wire fitting for the kingpost snapped, and we had a radio receiver/servo failure in the tail. The latter two might have been partially related to the higher wind conditions. So we were done for the day.
Videos of Alec's Flights:
Alec Proudfoot Flight #1 from Chase Bike, 125 m
Alec Proudfoot Flight #2, 178 m
Day 2
On Day 2, the intention was to get as many of the remaining pilots (all of whom are more athletic and better suited for longer flights than I) flying if possible. However, I thought at best we would get 2 or 3 pilots in the air.
But we lucked out and it was a near nil-wind morning, with wind usually below 2 kph, and the highest reading we saw was about 3 kph. That meant that we could fly the airplane in either direction down the runway, saving precious time. (it would take 20 or 30 minutes to walk the plane all the way back down the runway to try another upwind takeoff, had there been wind)
Fixes were made to the tail controls (servo and receiver) and the broken kingpost support wires, and the plane was ready to fly again the next day. (The servo & receiver failure was caused by high power going through the receiver due to high load when the wind came up -- rewiring avoided this problem in the future, so that the power line for the servo no longer is routed through the receiver, but comes directly from the battery. The Kingpost is not necessary for flight, and in fact will be removed entirely during record runs to reduce power, but is used to hold the wingtips up prior to flight to help make ground handling easier. We replaced the broken steel wire fittings with braided Kevlar cable.)
Everyone got to fly. Conditions were perfect. We couldn't have planned out a better day if we'd tried, and we learned a lot and all the pilots got some significant flight experience.
Greg Thomas went first. His first flight was 114 m long and had a long takeoff run. We noticed the clicking sound and discovered the damaged main landing gear wheel from the previous day (the tread had a large lump on it, though the wheel was still functioning), and were able to swap it out in about 5 minutes with a new wheel. His second flight was fantastic, 453 meters, up to near the end of the runway. (Again, this was in the 'uphill', higher power direction)
We turned the plane around, adjusted the seat, and then Craig Robinson flew almost the length of the runway, with a flight of 994 meters, only stopping because he was running out of runway. He could have kept going much longer if he had the room.
Control in both flights was quite fluid and worked well, with no problems.
In quick succession, we turned the plane around and Geoff Bower flew 601 meters in the runway 30 direction. Ginger Kroft, the first female pilot of DaSH, did a 290 m flight down runway 12.
Then we were running out of time, and needed to reposition the airplane back to the taxiway halfway down the runway, in order to get the airplane off the runway before the closure time ended (Half Moon Bay airport runway was closed down for us, and we had the runway from 6:30 a.m. to 9 a.m.). Flying the plane was quicker than walking it, so our final pilot of the day, Ariel Herrmann, did a short hop back towards the middle of the runway (actual flight about 15 meters, with a long takeoff roll and landing roll), ending up adjacent to the taxiway, where we then walked the plane off the runway to end the day.
We had found that our new circular chain guides on our top and bottom chainrings worked well and prevented the chain from skipping off (which happened back in December during test runs mostly from flexing of the fuselage on the rough pavement -- the chain bouncing smoothed out during flight).
However, on about half of the flights this weekend, the chain now came off of the idler pulleys instead. The chain still worked, it was just rubbing against the wood washers/spacers for the idler pulleys instead of the pulleys themselves, so that was adding extra drag to the drivetrain (interestingly, on both Greg and Geoff's long flights, the chain was off the idler pulleys the entire time...).
Ariel's flight was just a short hop because he realized that the chain came off for him as well, and he didn't want to put too much power into the system in that condition.
We'll fix this by changing the idler pulleys to be the type that have sides to them (similar to our circular chain guides for the main chainrings) before our next flight.
One other issue that came up was we had significant dew both days. This affects the performance of the plane in 2 ways -- added weight, and decreased airfoil performance. We don't know how much this affected the performance of the plane (roughly, it looks like 30 to 50 extra Watts (not counting uphill or downhill power adjustments as described above) were needed by each pilot compared to predicted). We expect much of this is due to dew, some of it due to unfaired parasite drag items like the wing mounts, and some because we flew without the pilot door covering so there was extra fuselage drag. We'll work on fixing these things (the dew part will be a matter of weather conditions) before our next flights.
That's is for now, we hope to continue improving the drivetrain and decreasing the drag on the plane during out next test flights, and once we have longer flights, and have gathered more power data, we hope to move to the desert for even longer flights, hopefully sometime later this year or early next year.
Below are videos of some of the rest of the Day 2 flights as described above...:
Greg Thomas Flight #2, 453 meters
Craig Robinson 1 km flight from Chase Car
Geoff Bower flight, 601 m, from Chase Car
Ginger Kroft flight, 290 m, from Chase Car
Ariel Herrmann, short hop to reposition plane on runway
