Month: September 2014

Last Days of Summer?

The Sun’s out, it’s hot and the wind is non-existent. Most people seem to think that this is the last good weather before Autumn hits us, so it’s really busy. I managed 3 flights with the RS352, mainly practising prop hanging. The LiPo on the first flight felt like it didn’t have the normal level of power (pack #3), so it might need replacing soon. Despite that, on the first flight I managed to sustain a perfect prop hang for longer than I have done so far.

In addition to the RS352, I also had four flights with the HubSan X4, using every one of the four LiPos until the eyes were flashing at me to signal that the pack was exhausted. Last week I de-soldered the power lead, tested it for continuity and found nothing wrong with it. After soldering it back on, I still couldn’t find anything wrong the the X4, so I put it pack together and connected the power again. It managed to bind with the TX, but, as soon as the power went above a certain level, all power to the quad cut and it reset itself. By putting it on the ground and gradually increasing the throttle, I could see it cutting round about the 10% throttle point. It was as if beyond a certain load the voltage dropped below the cut-off point, except that this was a brand new LiPo. Anyway, by some combination of reset and fiddling around with it (go into expert mode, left stick to bottom left and waggle right stick left and right until eyes flash), I managed to get it to fly. If anybody can tell me what it means when the left eye flashes while the right eye is solid blue, I would really like to know. It keeps doing this, which must be some sort of error code, I I’ve searched online everywhere and can’t find any explanation for this.

Anyway, as for the rest of the flying, I watched the maiden flight of an ST Models Blaze electric glider. It actually went completely behind a rather large Oak tree at one point and we all thought he had hit it, only for the model to suddenly re-appear climbing over the top. That must count as the best rescue I’ve seen for some time. There was also another small quad which seemed not to want to fly, the usual aerobatic EFlite Advance 25e and a very slippery 3 metre electric glider.

Back in the air again

This morning must count as insanely windy, but I still managed three flights with the RS352. Flight 3 was interesting as I lost power on the landing approach and came down short. The previous landing was even more interesting as for some strange reason I landed the wrong way, going almost with the wind.

Other than that, I was joined by some people with a Parrot AR Drone what just went increasingly further downwind and didn’t look like it or the pilot could handle the conditions. There was also a Blade Quadcopter that ended up downwind and caused damage, so not a good day for multi-rotors.

I recorded a video of the RS352 sitting on the ground getting buffeted by the wind just to prove how bad it really was. It’s up on vimeo at the following link: http://vimeo.com/106756720

No Flying this Week

There’s no flying this week due to the cycling event and all the roads being closed. I’m going to use the time to try and fix my HubSan X4. It looks like the problem is power related, but I can’t find the cause. One minute, there’s no power, then it binds leaving one eye blinking at me. Then I managed to get it to work briefly, but it was completely out of trim. I really need to examine it in more detail to try and find the cause.

Wing Thing in Autumn

Wing Thing had its second outing today, with two successful flights of over 15 minutes each. I really need to find a way of flying and photographing it at the same time, as it has such an iconic shape in the air. The first launch with the 7×3 Graupner folding prop was a bit of a disaster, with too little power it just hit the ground. The propeller was over-revving as the ESC was skipping with the throttle at 100%. Switching back to the 8×4.5 Graupner folding prop was a massive improvement, resulting in more power, throttle usable over the full range and a 15 minute flight. With this CG position (full forward), the aircraft was very nose-heavy and I was having to hold about 20% elevator to stay level. I had to make one aborted approach to land due to too much speed, but the actual landing was fine, if a little fast. This airframe’s drag is obviously very low as it moves deceptively fast through the air. Landing is tricky because of the speed and the fact that, as the speed comes off, the elevator loses effectiveness and becomes just an air brake. There doesn’t seem to be any way to float the aircraft in, you just have to run it along the ground almost flat.

The second flight was similar, but the CG was moved back 10mm by moving the LiPo. This resulted in a reduced nose heavy feel, with power on balance having zero pitch down but, turn the power off, and the nose drops rapidly. This is great for launching, which was scaring the life out of me, as this time it flew away from my hand without me having to grab the elevator. My impression is that the CG can go back a bit more, but the wing incidence needs to be increased to reduce the thrust/wing incidence angle for the power off trim to match the power on.

I’ve just finished recharging the first LiPo pack and it’s put 612mAh back into a 1300mAh 3S pack (to 80% storage), which was showing voltages of 3.8v at the start, so it looks like 15 minutes is about the flight time to expect. This was with me saving the power and gliding (badly) for parts of the flight. Interestingly, the second pack only put back about half that after recharge, so I obviously didn’t take as much out of that pack.

In addition to the wing I also flew my HubSan Q4 quad as the new batteries arrived from RobotBirds earlier in the week. I was hoping to fly the X4 as well, but the new batteries for that haven’t fixed the power problems I’ve been having. The X4 just doesn’t want to power on. I’ve tested the voltage all around the circuit, so it’s not something simple like a broken connection. I’m going to have to open this up and have a closer look later.

I also managed to fly a ParkZone Radian which was quite eventful. The aircraft seemed very good until I got some distance from myself about two minutes into the flight and lost control completely. The first indication was the rudder not turning the aircraft, followed by the realisation that I had no control at all. This is unusual with modern radio sets as the range was probably only about 30-40 metres. It really wasn’t that far away and was still quite low, so the Planet 9 radio should have still worked even if it was only a park-fly receiver. In the event, the power off and slight up failsafe setting resulted in about four or five stalls with the aircraft circling around the same position, so I was happy to let it come into range again. Once I had it under control again, I flipped it into wind scrubbed off all the height and speed and brought it down as quickly as possible. Further investigation of the receiver aerial suggests it might have been twisted, but future flights will use a better receiver.

Finally, I also watched an F22 made from Depron card fly exceptionally well, plus a Mustang made from the same materials fly not so well. And I nearly forgot some HLGs that turned up part way through the morning.

 

Wing Thing Post Flight Test Data:

Measured with 8×4.5, 1300mAh 3S LiPo: 11.7 amps, 133 watts, 10,620 RPM

Stated no load RPM for a Typhoon Micro 6/3D is 10,800 RPM, so my RPM figure looks rather high (98%). Also, max power is stated at 90W, but the suggested prop for a 3S is 8×3.8, so I must be in the right area. Most of the flight only used 50% throttle anyway.