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| First Flight at Moffett Federal Airfield -- Alec Proudfoot piloting photo by Wink Saville |
Video of first DaSH Moffett flight June 25th
360 degree VR video of first DaSH Moffett flight June 25th
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| Craig Robinson on his 1.3 km flight at Moffett Federal Airfield |
We had 5 successful flights at Moffett near the end of June, including the longest flight so far (1.3+ km). The last of the 5 flights ended in a shallow dive into the pavement instead of a smooth landing, doing some damage to the nose wheel and the front of the fairing, which will be repaired to make the airplane better than before (more details below).
For this third round of testing, we moved to Moffett Federal Airfield. Moffett has two very long runways -- Runway 32 L/14 R, which is 1.55 miles (2.5 km) long, and 32 R/14 L, which is 1.73 (2.78 km) miles long. Unlike our previous test site, Half Moon Bay Airport, which has only one runway that had to be shut down entirely during our early morning tests, Moffett's two runways allow the airport to remain operational for incoming/outbound flights while we were testing. This is convenient because it allows us to operate as long as winds are favorable, rather than having to shut down earlier in the morning. It is also closer to our home base, only minutes away from our workshop.
Because it remains an active airfield during our testing, we had to undergo training a few weeks before our tests, so that we could learn how to properly operate and follow airport procedures. We had 18 crew members successfully complete the training ahead of our test flight date.
Day 1, June 25th 2016
On Saturday, June 25th, I (Alec) flew first to test out some of the changes we had made since the previous time. We were checking to make sure the changes to the idler pulley worked to help keep the chain on (we switched to pulleys with side channels), and also ended up testing out the new main gear wheel.
When we were wheeling the plane out to the runway, we had another failure of the tread of the blow molded plastic main wheel. So we switched out to a new, slightly heavier (by 150 grams), main wheel that has a grey rubber tread. We also had some issues with the avionics sensors and couldn't get airspeed and rpm readings to work. After fiddling for about 15 minutes, we decided to move on and fly as-is.
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| The new wheel, with grey rubber tread |
My first flight to shake out the changes went great -- I flew almost three times as long as my longest flight before, going 636 meters in 1 minute 20 seconds. I tried getting higher at the start of the flight and got up to about 2 meters, then in the second half of the flight was back to about 1/2 to 1 meter height. The pedaling got easier there and I was able to continue on about 30 seconds beyond when I initially thought I would need to land because of fatigue -- I think I must have trimmed the plane slower, but given the balky airspeed sensor, we couldn't tell for sure.
Alec's flight from chase bike
Alec's flight in 4K video (Slight SloMo ~80% speed)
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| First flight at Moffett Federal Airfield |
The plane was now positioned in the approximately halfway down runway 32 L, and Geoff Bower took over. He had a good flight to the end of the runway of 700+ meters long (exact distance not determined due to GPS recording failure, but using visual marks, it was 700+ m).
Geoff's flight, from multiple angles
Geoff Bower's flight in 4K video
(Slightly Slo-Mo ~ 80%)
360 Degree VR video of Geoff's Flight
It turned out that the turntable bearing we were using on the nose wheel was fairly weak, and some combination of landings in February at Half Moon Bay Airport (particularly the last one where we went off the runway), and the two landings on the day at Moffett, had spilled enough of the ball bearings out that it couldn't function anymore. Unfortunately, we didn't bring any spare parts for that part. But we had some back at the shop, a 15 minute drive away.
Nose wheel break on Craig's first attempt
Once we got it fixed, the wind had picked up a bit. Craig had a long flight, over 1.3 kilometers, our longest so far, but he got bounced around a bit by turbulence. We probably wouldn't want to fly in any higher wind conditions than this.
At the end of the flight, he had a left crosswind and had to put left rudder in to try and keep the wings level, and this caused the plane to roll off the right side of the runway. When it hit the gravel off the runway, the front wheel stopped abruptly and the bearing failed again, spilling ball bearings out. We had a spare this time, but due to the wind conditions, decided to go back to the setup area and break down for the day, and fix the front wheel bearing.
Craig's 1.3+ km flight at Moffett from Chase Bike
Craig's 1.3+ km flight in 4K video (80% speed)
Craig's 1.3+km flight in 360 VR video
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| Craig up high during his 1.3+ km flight |
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| Working on the nose wheel bearing |
Day 2, June 26th 2016
After repairing the nose wheel bearing the previous evening, we were out of spare bearings, so we bought a different kind of caster wheel at a hardware store as a backup.
First up to fly today was Greg Thomas, who'd had a couple of flights back in February at Half Moon Bay.
Setup went quicker the second morning because we were practiced, and because there were fewer planes on the ramp and we got to set up under a large bank of lights, which really helped.
Greg's first flight was short, 125 m and 18 seconds, as he had an unexpected landing early on, and due to the angle with the runway, wisely decided not to try and takeoff again.
Greg's first flight, 125 m, 18 seconds
Once again, we had the same issue with a crosswind -- on landing the pilot had to yaw to keep the wings level while the wing chasers ran to catch the wing cords. This caused the plane to yaw towards the crosswind direction and roll off the runway edge, then stop abruptly on gravel. With no brake, the pilot had no way to stop the plane until the wing catchers caught up with it. (We'll fix that next time, see below.)
Once again, this broke the turntable bearing on the nose wheel. We were out of spares of that part, but in less than half an hour were able to fit the different, slightly heavier caster wheel we had bought at the hardware store the night before into place to make the plane operational.
Greg's second flight had a bit more wind and he had to correct a couple of times on to try and keep the plane on centerline. Unfortunately, our current joystick doesn't have a good detent feel or enough spring to differentiate the pitch and roll axes, and he inadvertently put in some down pitch while focusing on correcting the roll. The plane did a shallow dive to the runway and he wasn't able to recover in time. It hit at too steep of an angle for the nose wheel to roll, and there was some damage to the nose wheel assembly -- the carbon tube broke off -- and there was some damage to the front of the fuselage fairing. Greg was unharmed. The prop also hit and sustained some damage, but should be easily repairable.
We're looking at this as an opportunity to fix some things that needed fixing anyway -- we're going to replace the turntable bearing that was causing us so many issues this time, and replace it with a setup with two bushings. The fairing nose was always a bit bumpy and too wide, we are going to replace it with a molded Kevlar nosecone that will be about 80 mm narrower, and also smoother, hopefully cutting down on drag.
Greg's 2nd flight and subsequent crash, from Chase Bike
Greg's 2nd flight and crash from multiple angles
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| Damage to fairing nose after the crash |
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| Broken nosewheel tube |
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| Damage to pilot seat It survived quite well, the mesh took some of the impact load |
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| Damage to propeller tip |
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| Rib damage from prior ground loops |
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| Ground handling damage to vertical tail |
After reviewing the damage, we have a plan for fixing the nose wheel assembly, building a new, smoother fairing nose and repairing the damage to a few of the ribs that came from some of the semi-ground loops on earlier flights. We also have come up with a multi-part solution for ending the off-runway excursions that were causing us problems, which involves a hand brake on the main gear so the pilot can slow the plane, longer wing cords for the wing catchers, and different procedures on how to catch and stop the wing.
More photos from both days, June 25 & 26, 2016
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