Month: August 2017

The End of August

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My RS352, captured using the high dynamic range (HDR) setting on my Nexus 4.

I’m sad this week because I haven’t got my Autogyro to fly. Never mind, though, because it’s Bank Holiday weekend, so I’ve got the whole of tomorrow to do the repairs. All I need to do is to epoxy the spruce 6mm square longeron where it’s split on the right tail, add some ply reinforcement and cyano the right fin back on. Fairly minor really, but I just didn’t get time during the week.

As for this week, the weather was just about perfect again. There was already somebody flying a drone at the edge of the field when I arrived, plus another guy flying a Blanik way down the main path. I’m not sure if it was a glider, even though I saw it flying and said hello to him as he was walking past me back to his car.

Anyway, soon after that we had one father and son with a foam board F18 and a new Hobby King Prime Jet Pro. Both flew really well, but the F18 had rather an untimely end. The wing disintegrated in mid air and it crashed, with parts of the wing debris floating down into a tree. The fuselage didn’t have a bad crash considering, and all the gear was salvageable. We also had another father and son, this time with a fairly new SIG Kobra that they had flown for the first time the day before. He was still a bit nervous landing it, so I ended up standing next to him and talking him down on the first approach. Later in the morning, and after he had had a few flights with it, things got a little bit interesting. He took off and the telemetry told him that the flight battery was low and he needed to bring it back in quickly. Luckily, I hadn’t quite launched my RS352, when he asked me to land the Kobra, so I could put my plane on the ground, pull the power connector out and take the Taranis transmitter off of him to fly the Kobra. OK, so I’ve never flown this aircraft before. I flew across in front of myself and started a slow left turn upwind, thinking that I would fly downwind, turn onto final approach and land. I didn’t even get that far, because I could feel the power going half way around that first turn, so the best option was to complete the turn so that the plane was pointing directly towards me and land with the wind. Trying to manoeuvre, even a fairly lightly loaded pattern ship, as the speed and height are both reducing is never a good option, so the first turn I had made with this aircraft was going to have to be the final approach run. It all worked out well in the end and I managed what I called a reasonable landing with the wind in rough grass. The undercarriage survived unscathed and I didn’t damage anything, so mission accomplished. I actually wouldn’t mind one of these myself, as it looked like a very nice aircraft.

We had a few more visitors this morning, with the Sky Surfer from last week, but he had also brought his UMX Tupolev WW1 biplane. I still can’t work out precisely what aircraft this is, so I’ll have to do some more background research. It’s brown and had a penguin roundel (yes, really). Bringing WW1 back to life, we also had a red UMX Fokker DR1 triplane (quadriplane), which I first flew for the owner a few weeks back. Two of us had a go with it today, but it just didn’t have the power it had before and refused to fly. Eventually I worked out that the problem was where the engine cowl had been glued back on and it was now rubbing on the prop and obviously losing thrust. Despite my best advice to take it home and fix it, the owner wanted to see it fly, so he borrowed my scalpel to try and prise the depron cowling away. This didn’t go well, as it turns out that inside the top centre point of the cowl there is a beam and electronics board carrying the rudder and elevator servo. I was worried about cutting motor wires and it turns out that the radio, speed controller and servos are all housed in the engine bay. To cut a long story short, we had cut one of the wires to the elevator servo and destroyed the beam that the servos and electronics were mounted on. In other words, both servos were now no longer attached by anything other than the push rods. I felt really bad about that, but I had told him to take it home and fix it as these types of aircraft always require micro surgery.

In addition to this, we also had the lady on the scooter with her tiny drone, then a family with two kids and another toy drone, two people who I haven’t seen before with a Bixler and a drone (Mavic?), another guy with a DJI Phantom in a holdall, the professional drone pilot with his DJI Inspire keeping his flying hours up and another couple who I’ve seen a lot with a DJI Mavic. Yes, it was rather busy towards lunch time.

As for my flying, I got in four flights with the RS352, which was strange as it was quite a long way out of trim. My first thought was that the trim I had from the ATOM last week was applying when the model was set to RS352. My radio is a Futaba Field Force 8, and that’s not how it works as I checked after the first flight. It’s odd, but I had a lot of right aileron trim (about 10 clicks), most of which got taken out as the flights progressed. I can’t really explain that, but I still had four good flights.

I also got to fly the Sky Surfer as it’s owner was having problems with hand launching it himself. He threw it a couple of times with me flying it and I gave him the controller once it was in the air. I flew the DR1 a few times until I figured out what was wrong with it and I also flew the SIG Kobra, even if it was only briefly. All in all it was quite an eventful morning.

Right, I’ve got the rest of today and the whole of Monday left, so I’m going to fix my autogyro.

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Autogyro Flies!

After starting the build in Autumn 2014, I can finally say that I’ve fulfilled my ambition to fly my own autogyro. It didn’t all go completely to plan, though.

Last night I added a bit of extra shim to the blades to help with the spin up:

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LiPos charged, I was ready for the first flight of the day, so, here we go again…

 

I decided to use the wind to spin up the rotors and then hand launch, which worked last week when I got my first 10 second flight. This week it was a bit windier at around 8mph, which I figured was perfect. This time I had the trims zeroed, so the head head was at 90 degrees to the mast, which is the recommended position. I tipped the aircraft back so that the nose was vertical, the blades spun up to a speed where there was a definite “lifting noise” from them, increased the throttle and rotated to the horizontal launch position and released the aircraft into the air. Immediately it wanted to go backwards and I spent most of the 20 second flight with the elevator stick all the way forwards trying to control it. Anyway, the landing wasn’t too bad, in long grass over to my left and downwind. On recovering and checking the aircraft, I discovered that the right fin had snapped in the landing.

 

I borrowed some cyano and patched it up with sellotape, then I moved the elevator trim all the way forwards and gave it another launch. I had a four minute flight with it this time, flying backwards and forwards in front of myself, demonstrating some semblance of control.  This time I was actually flying it, even if it was a bit of a handful to start off with. The thing is, it was pulling badly to the right, so I spent the first few minutes gently dabbing in a couple of clicks of left aileron trim until it was flying more comfortably. That’s 25 clicks of left and about the same on the down elevator prior to flight, which explains my earlier comment of, “a bit of a handful”. Especially when you’ve never flown an autogyro before, and it is a very odd thing to fly. Also going through my mind was the fact that the fin was held on with sellotape. That’s why I was very reluctant to use the rudder, but I did  give it a go near the end of the flight.

As for the flying, the elevator controls the speed, while the throttle controls the height. I did actually get up quite high at one point, but I was very careful not to let it get too far away from me as the orientation is a problem. I had a couple of moments when it was turning towards me and I lost orientation. What really surprised me was how much height I was losing on the turns. I was flying off to my left, turning 180 degrees, losing half my height, then picking the height back up again as I flew in front of myself, only to lose it again on the turn at the right hand side of the box I was flying in. It didn’t seem to matter if I turned left or right, the height loss was the same, and there were a few points where I couldn’t turn tight enough to fly in front and had to do a big circular circuit around my head. There didn’t seem to be much authority in the turns, but I can live with slow and docile at this point. Like I said before, I did very gingerly try the rudder out at one point and it was effective in bringing the nose around, but I was too scared of the cyano and tape on the fin giving way to do very much. Anyway, that was the battery exhausted, so I had to think about landing. This proved to be very easy and I touched down with almost zero speed and so lightly I’m sure my pilot in the red baseball cap never even realised. The only thing to mention here is that it’s very important not to reduce the speed too much. I was on the point of doing this and could feel it rolling left as the speed was decreasing. Post flight analysis of the battery showed that it only had 10% left.

Four minutes of autogyro flight! I’m only saying that again because it goes a bit downhill after that. On the next flight, the launch was fine, but it just didn’t seem to have any power. I can’t understand it because I did two launches, and both times it didn’t want to climb, landing about 20 seconds later. On both occasions, there was ample power when the aircraft was recovered. I decided to charge up one of the new 1300mAh packs and see what difference that made, but I’m fairly sure I made a mistake launching. There wasn’t enough speed in the rotor when I released it, the aircraft went away, but climbed too fast and rolled to the left. It was like it did a stall turn from my hand and I almost managed to recover it, but it hit the grass quite hard on the two wheels and tail skid simultaneously. This had the effect of partially splitting one of the spruce longerons and put paid to any more flying.

 

I always suspected that a hard landing would cause a break like this, but it’s easily fixed with some glue and a couple of plywood doublers. In my defence, I think the rotors were spinning at the right speed, right up until the point where it left my hand. The wind dropped at just the wrong moment, causing the rotor speed to drop as I brought the aircraft up to the horizontal and applied throttle.

Anyway, I’m very happy now that I’ve achieved my lifelong ambition to fly an autogyro, so I’ll fix it up and have another go soon. Oh, and by the way, there should be video of the event, assuming the camera worked. I haven’t had time to look yet. Post-flight analysis of the flights were there was no power could be interesting. I’m wondering whether I was pulling back on the elevator more than I realised, rather than giving it throttle? I really don’t know, as I definitely had 100% throttle and had to back off to land. Would forward tilt have increased the speed and built up lift? What I would really like is some sort of telemetry to record my transmitter inputs along with the flight video.

As for the rest of the day, I had a single flight of my RS352 right after the final flight with the autogyro. I buzzed around the sky with an old Corsair, which was a lot of fun. We were dogfighting with each other, but pretending that we weren’t. Him and his father between them had a fair few aircraft, including a Lazy Bee and a UMX Beast, which I’ve flown before and which he threw around the sky very convincingly. There was another guy who helped me with the autogyro last week, but this time he had brought his son and was teaching him to fly with a buddy box. I haven’t seen that for a long time, but together they were flying a Bixler. I also discovered that the aircraft I maidened last week wasn’t a Bixler, but actually a SkySurfer. The same guy was here again this week, but with his Nieuport biplane this time. Unfortunately, the Nieuport had a bit of an incident on its first take-off, then got into the air, completely out of trim, gradually settled down into flying, but suffered another incident on its second flight. This time it looked like the top wing was damaged, so he went back to his car and brought back a contra-rotating helicopter. This also flew, but it looked like the wind wasn’t its thing. When I had to leave at the end of the session, I left him with my sellotape fixing something on it. We also had a lady with a micro drone, brushless, and made from carbon fibre. I think I last saw her on the autogyro’s first outing a few weeks ago, but a couple of her friends also turned up with drones. There were also another couple of drones at the opposite ends of the field not wanting to talk to us (I wonder what they made of an autogyro flying past?). Finally, the guy with the Bixler also had an own design, small, agile, high wing plane that he spent the best part of a decade building. He asked me to have a fly of it and see what I thought. Well, it’s actually very nice to fly. I thought it was going to be very sensitive to roll, but actually, the controls were very well balanced. It was fast, agile and aerobatic, without being overly so. Anyway, he’s got a SIG Cobra pattern ship type plane that he’s just finished and wants to fly next week.

That’s about all there is for this week, except that I’ve still got the video of the autogyro flight to have a look at and edit, plus some repair work to do. I’m still determined to make the autogyro a regular flier.

The Night Before the Autogyro Test Flight

I’ve spent most of today getting the autogyro ready for its third test flight tomorrow. Firstly, I now understand what the shim under the blades does. As the blades are fixed to a flat disk that spins, if the blades were at zero degrees incidence, then all the lift produced would be upwards. The shim gives the blades negative incidence, so there is a small component of the lift in the forward blade direction. Now, with the blade fixed to a spinning disk, this forward component of the lift makes the blade spin. The more negative incidence you add, the more force there is to spin the blades.  There must be an optimum amount of incidence which causes the blades to spin at the correct speed to produce enough lift for flight, but I haven’t worked it out yet. I’ve just added a bit more to my blades for tomorrow’s test flight. It’s easily removed if it doesn’t work, though.

The next thing I did was to correct the tracking by bending the left u/c leg back into position. I can’t think how it got bent… Now it looks nice and straight, so I’ve moved on to looking at the control movements. There isn’t much I can do here, except make it all nice and square and get the head back to 90 degrees to the mast, which is the suggested neutral trim position.

Then I had a look at the videos of last week again. It’s all very consistent when you watch. As soon as it gets to a certain speed something kicks in and it yaws abruptly to the right. After wracking my brains about P effect and gyroscopics, I realised that I was missing the obvious. It’s almost certainly the reaction force as the the rotor head spins anti-clockwise. The yaw force is clockwise, so that great big triple rotor on the top is the most likely culprit. I took the head apart, I oiled the bearings and I put it back together again, which is about all I can do with it.

That’s all there is to it really, so I’m hoping for some wind tomorrow so I can do a hand launch. We’ll just have to see how it goes.

First Flight: The Autogyro Flies

 

I flew the autogyro! I don’t care about anything else at the moment, I finally flew my own autogyro. As an added bonus, I also managed to catch the flight on my RunCam. I honestly thought I was gyronauting for at least 30 seconds, but the video says it was only 10. It must be down to the number of control inputs I was having to put in, because this was one first flight which didn’t exactly go to plan. To begin at the beginning, I put bigger wheels on the Atom to increase my ground clearance and hopefully help the ground run build up rotor head speed. You can see the big foam tyres in the pictures. I must have spent the best part of an hour running along the ground with it doing exactly the same thing every time. There’s lots of video of that too so I can analyse it later. The aircraft runs straight initially, then veers off to the left as soon as the head gets to a certain speed. I tried altering the head angle (aileron) and rudder to counteract this, but to no avail. If I did get up enough ground speed for the head to spin fast enough to lift, then what would happen is that the right wheel and tail would lift, but the left wheel refused to unstick. I got very proficient at careering along the ground on just the left wheel and dragging the left fin, before crashing into the grass at the left edge of the runway. I just couldn’t get it to track straight and really need a fatter section of flat grass to take off from. The wind wasn’t helping either, because it was very thermic and the wind was from all directions during the morning, but never much more than about 5mph.

To cut a long story short, I hand launched it. One of the guys flying DLG had come over and suggested hand launching, but I was very reluctant, unless I could see the rotor spinning up to speed first. This is where I now owe the weather a favour. While I was discussing the YouTube video I had seen on how to hand launch an autogyro, the wind picked up, the rotor spun up to speed and I just looked at him and said, “that’s it”. With the autogyro’s nose pointing vertical, the rotors were spinning furiously in the wind, I did a control check, rotated it smoothly to horizontal and pushed it forwards. It flew. Well, I say it flew, for the next 10 seconds I had the sticks in all four corners in order to avert was was increasingly looking like a crash. I think my helicopter flying skills kicked in at this point, because that’s what I was doing, watching the rotor head, keeping away from the ground and trying to stay flat and nose down. Needless to say, the head was too far back and it was flying on a stall. Everybody thought it was going to crash, but I’m able to walk away with 10 seconds of autogyro flight, an undamaged aircraft and a lot more knowledge about autogyros. I can’t wait for next time.

Autogyros aside, it was a very eventful morning for other reasons, not least of which because the weather was perfect and there were more people and aircraft than I’ve seen in a long time. There were already three guys flying DLG exceptionally well when I arrived and another with an own design trainer using the path as a runway. Then the guy from last week arrived with his F15, bringing along his daughter this time. I got to launch the F15 on its first flight. Somebody was flying a drone (noisily) over by the river. My first flight of the day actually came from the guy who brought a UMX Spacewalker over on his bike. The Atom was actually my second maiden flight of the day as another guy I see a lot had a brand new Bixler. I flew his Hurricane a few months back, and he was going to fly this himself, but then we got into, “I can stand next to you while you fly if you want… can you launch it for me… why don’t I just give you the transmitter and you fly it?”. So I flew it for him, which was probably a very good thing. I noticed on the ground that there wasn’t much aileron movement and it really did need more in the air. Luckily the rudder worked OK. I had to check the rate of ascent from the launch, as it wanted to go vertical, then it was rolling left badly, so ended up putting in lots of right aileron trim. I was fairly happy with it flying more or less level by this point, but it was sluggish and really wouldn’t turn right. I was holding in full right aileron and nothing was happening. I kept increasing right aileron trim, which did help, but it needed more movement. Landing was interesting, as I lined it up to run past in front of us, I realised I needed to correct to the right, nothing happened and I elected to add power to go directly over our heads and go round again. The landing on the next circuit was perfect. The owner then added more movement, I took it up again and handed it over to him. It flew perfectly after that and he had a few more flights on his own. I was really impressed at how well it would glide. Although I called it a “Bixler” earlier, it might have been one of the other clone versions, but basically, it was a Multiplex Easy Star type.

We had two more arrivals in the form of the guy who flew the Witch drone at Halloween last year, who was flying a Mavic. The other was a guy I’ve known for ages, who usually has a Stryker, but this time had a UMX A10. He broke something on the first launch and had to tape it back together, but his one and only flight after that was very impressive. The Mavic had a go at filming my adventures with the Atom, but I think the only footage he would have got was me crashing into the grass at the side of the runway. There were at least two other people flying drones by lunchtime as well, so there was so much activity this morning I couldn’t keep track.

After messing around with the Atom almost all morning, I also had two very quick flights with my RS352, swapping LiPos and going back up without even switching off the transmitter. The time on my transmitter display shows 50 minutes this morning, most of which was with the Atom. So, just to recap, the planes I’ve flown this morning are: UMX Spacewalker, Bixler (Maiden), Atom (Maiden) and RS352.

Anyway, I’ve got about an hour of autogyro video to analyse before my next flight.

 

Daisies

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The wind forecast for this weekend was 8mph and I really wanted to test the autogyro again, but I only had the bike this week. As it turned out, the wind was much stronger than expected, at least for the times when I was flying. It seemed to go calm as soon as I touched down.

Try as I might, I just could not figure out a way of getting the autogyro onto the bike in any way that would see me get it to the field in one piece. I thought I could do it by unscrewing the saddle clamps and removing the wire undercarriage, but that still leaves the mast and tail. In the end I had to accept that it was too big and take the mini flying wing in its purpose bought ruck-sack. At least, that is to say that I bought the ruck-sack and designed the flying wing to fit in it.

When I arrived at the field this morning, the first thing I noticed was that it was full of daisies. I’m not that good on flowers, but there were thousands of little yellow flowers everywhere all of a sudden. You can see what I mean in the picture. The second thing I noticed were two people with drones, standing at either end of the field and me in the middle. They obviously didn’t want to talk to each other, or to me, so that’s fine. One of them seemed to be flying FPV like a complete nutter anyway.

Very soon after I arrived, a guy I’ve known for a long time turned up with his son, an F18 and an SU27. Both were made out of depron, but the SU27 was a very light profile model. The F18 had notably better performance, very fast and able to climb vertically in a sustained manner. That’s not to say that the SU27 was a lot slower, but it was lighter, less powerful and had a very draggy airframe by comparison.

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When I did finally get around to putting my wing together, I had the usual problem of trying to figure out where to put the battery to make it balance (NOTE: mark it inside the fuselage this time). I think the combination of wind and slightly rearward C of G lead to a very interesting first flight as it was best described as skittish. I was a bit worried that the motor shaft was bent from the last outing, but this wasn’t evident. My nerves were really on edge after the first 10 minute flight, but I still went up a second time and had another 10 minute flight with the C of G a bit forward, which was a bit less on the ragged edge. The glide isn’t too bad, but there didn’t seem to be any big thermals around, despite my trying to sit under a big, threatening looking, black cloud which was blocking out the sun.

Two flights is usually about all I can manage with this aircraft, before I decide not to push my luck any further. Maybe I’ll try making some modifications to improve the performance, because it’s been a bit of a work in progress for the last 10 years or so? We had an interesting discussion about LiPos puffing up and storage charging while we were comparing the eBay LiPos in the F18 to my Hyperion ones. Apparently, it’s supposed to be 43% with a balance charger, not the 80% I’ve been storing mine at. After the mini wing’s flight, we had a look at the remaining capacity of my 3S 1100mAh pack with a battery checker and it reported one of the cells as 0.5V! Although it looked like a different version of my own battery checker, which I left at home, this obviously couldn’t be right. Either that, or one of my cells is dead. It turns out that not all battery checkers are equal, as all cells from both the packs I used this morning checked out at between 3.6V and 3.8V, so they’re fine. This is what I suspect about the puffing up problem, though. I think the balancers can measure the cell voltages wrong due to bad connections, thus over charging the LiPos which are then stored for a week, or several weeks if I’m really unlucky with the weather.

As I was going home the couple with a Mavic and a pop out landing circle arrived. They also set up about 20 metres away, so obviously didn’t want to talk to us.

OK, so I’m off to put the wheels back on my autogyro and see if it’s windy enough in the back garden to get the rotors running fast enough to feel them lifting. Let’s hope next weekend is sunny and calm.