Puri Flies Again and So Does Rogallo

I flew the Puri for the first time since its mid-air with a Multiplex Fun Cub back in October. That’s how bad the weather has been recently, but today was grey, murky, but crucially there was no wind. It did rain a bit later though.

What I discovered about the new Puri was that it was now flying just like it had on its initial flights. I’m fairly sure that it was a broken trailing edge that was causing the strange screwing out of loops behaviour that I was seeing before the accident. Now that it’s had the leading edge replaced and the trailing edge patched, it’s flying just how it is supposed to again. My three hand launches this week were good enough not to hit the ground, although it was a close call on the first launch where I had to grab for the up elevator rather quickly. But, crucially, there was no hitting the ground hard, which was obviously what had caused the broken trailing edge in the first place. I had three flights of around 10 minutes each, which seems just about right as the batteries are coming off at about 3.81v. And it was a lot of fun flying the Puri around, cutting up vast swathes of sky as it fits the old cliche of it “flies like it’s on rails”. It really does and I managed to hone my timing on rolls to minimise how much height I was losing. I also did some spins, which look very spectacular, but stop the moment you centre the sticks.

We had three people flying drones and one slightly more exotic customer. A Rogallo wing using a foam board Spitfire fuselage from an old plane that had crashed a while back.

This is basically a kite on a boom that has a Spitfire fuselage hanging underneath it with rudder, elevator and throttle. It flew away from the ground beautifully, but control once it was in the air was a big problem according to the pilot. When the power was turned off it would screw out to the left, but rudder control with the power on was a case of applying rudder and waiting for something to happen. It certainly looked good in the air, but it’s going to need some modifications to make it flyable. It still made a successful landing, though, so it survived to fly another day.

It’s not easy to capture a flying picture, but these aren’t too bad. It certainly looks different in the air.

I nearly forgot, but, as this was one of the very few days with no wind, I also flew my Power Up 4.0 paper plane. I’ve just bought a new phone, so all my previous flight data seems to have been lost in the upgrade. Disappointingly, none of my flight data from this morning seems to have been logged. I had two flights of several minutes each, so I had high hopes of a trophy for my virtual cabinet. Flying the paper plane is a lot of fun and I now feel like I am in control using the “acro” mode for better response and the thumbstick throttle with phone tilt for rudder. I think that works better than trying to use two thumbs on the phone, one for rudder and the other for throttle. Tilting the phone to make the plane turn takes a bit of getting used to, though, because it’s not exactly easy. I had a lot of fun with it flying figure eights and even managed a vertical trick that I could never repeat when it went up and flicked around almost as if it was in a stall turn and combined spin. I did try a loop, but it doesn’t quite come off. To sum up this morning, I had fun with the Puri and then I had fun with the Power Up plane.

We were flying against a forecast of impending rain this morning and, sure enough, we started to feel the first drops right on cue and decided to make a hasty exit. I had to cycle back through the murk and a bit of misty rain, but nothing too heavy, just enough to cover my glasses so I couldn’t see where I was going. So, that was my only flying in November. Let’s see what December brings us.

Tinkering

Just don’t mention the weather. The wind is 19 mph continuous, gusting 36, and it was raining hard at the time I would normally be leaving to go flying. I finished covering up the hole in the Puri’s wing last night, where I had replaced the broken servo last week, so it would have been flying today if the weather wasn’t so bad. This run of three weekends in a row with crazy wind has made me think about what I need to fly in these sort of conditions.

I used to fly this aeroplane a good few years ago. It’s a Modellhaus Little Tinker and it’s fast, agile and has enough weight and structural integrity to cope with windy conditions. It’s been flown a lot as you can see from the battle scars. As far as I can tell, both wing tips have been knocked off at some point, there are scars underneath the wings at the root, the ailerons have some damage, the V-tail is a replacement and the fuselage has been completely re-glassed and sprayed. I flew it a lot back in the old days.

Anyway, now I’m wondering whether I can bring it out of its retirement as it’s not doing anybody any good just sitting in a cupboard gathering dust. The wing and fuselage are perfectly usable, but it’s going to need some modifications in order to be able to carry it on the bike. Firstly, I was thinking about splitting the wing into three panels to make it transportable. Given the damage it has already received, I feel less bad cutting into it than if it was in pristine condition. The interesting thing is that, looking closely at the top surface, it looks as though the rain, which it must have been subject to when it was flying, has eaten away at the varnish. The top surface definitely needs a good rub down and new varnish. I do like the wood effect finish, so I wouldn’t ever think of painting it, even if you can see the scars of the old repairs. Now, the problem is that the wing is 1.46m and I need panels that are around 50cm to make it transportable. The trouble is that the servo cut-outs underneath are not in the best places. I would have to cut along the line of the servo box so that the servos are on the edge of the outer panels. That would give a 45cm centre section and two 50cm outer sections with servos at their root ends. I think it can be done structurally, if I use carbon joiners as reinforcement, but it’s not how you would normally make it.

The fuselage and V-tail weigh 200g and the wing weighs 290g, so that’s basically a 500g airframe, then 3 servos, LiPo, receiver and motor could add another 200g, so the flying weight would be around 700g. Now, that’s significantly lighter than it was flying before, as it used to have 7x2000mAh NiCad packs (420g) and a beast of a brushed motor up the front. I can’t remember what that motor was called, but I’m sure I still have it in the cupboard somewhere. It was one of those big rare earth magnet motors from olden days before brushless was invented. In other words, the lower wing loading is good, but getting the balance point in the right place could be challenging and I might end up flying with an enormous LiPo just to make up the weight. I could live with that if it gave me longer flight times, but I always like to fly light, but, then, if I’m looking at flying in stupidly windy conditions, then extra ballast might be just the job. At the moment this is only a thought experiment, but I’ll do the maths and see if it can be made to work. The truth is, now I’ve got it out on the floor I want to fly it again.

This week’s tip involves how the Little Tinker got its wing tips knocked off and its fuselage and tail destroyed. I used to have a landing crow brake mix that was operated by one of my transmitter switches. Switch down and the flaps (ailerons) come down to the thermal setting. Centre is speed and up is crow brake, where both ailerons go up to slow down for landing. However, if one of the servos is a bit slow or sticks, then the other servo suddenly coming up on the switch puts the aircraft into a roll. Basically, you flip the landing mix and the plane immediately flips itself on its back. You go from perfectly lined up for landing to broken in the long grass in a fraction of a second, with everybody who was watching wondering what on earth just happened. In other words, DO NOT USE A SWITCH FOR CROW BRAKE! Use something progressive like a slider, or program a delay on the switch so that this doesn’t happen.

OK, I’ve got some Thinking and Tinkering to do. Let’s hope next week’s weather isn’t this wild and it will probably be the Puri that I’m flying again.

Optimistic

I was going to fly the Mustang today, so I got the bike out of the shed, packed my ruck sack and then it started to rain. I put the bike under cover and waited it out for a bit, but spent most of the morning looking at the radar on my phone. It was a bit optimistic to think that there would be any flying this morning as there was a huge band of rain that travelled across our area from about 10am until 11:30. There was a bit of a break in the middle and then the second band of rain arrived at the time I would normally be finishing my flying session. In other words, I would have got wet going there, maybe got in 45 minutes of flying and then got wet again coming home. Or, more likely, probably hide under a tree until the weather cleared up. Add to that the fact that the wind was gusting to 20mph and you can tell that it really wasn’t a great day for going outside.

Instead of flying I spent the time fixing up my Puri flying wing, as a replacement elevon servo was delivered during the week. I’ve been absolutely snowed under with work this week, so today was my only real time to do any building. However, I spent quite a bit of the day looking at the elevon and trying to avoid the inevitable of my having to use hot melt glue to fix it in position. Using hot melt glue to fix a servo is one of those jobs that is very easy on paper, but you only get one go at doing it right. So I looked at it for a long time and then decided that I had thought about it for long enough and it was time to heat the gun up and actually do it. I injected one blob of glue at the top servo lug and one blob of glue at the lower servo lug, pushed the servo flush into the hole in the wing rib and the glue oozed through the servo mounting screw holes. It had worked. In hindsight I used a bit too big a squeeze of glue, but I can live with that. The servo was in the right place and sitting flush with the wing rib and looking like it was fixed securely. The control horn rod went back on with no problem, although I need to remember to add a touch of glue to secure the end cap that stops it coming off the elevon. Now all I need to do is to close up the gaping hole I had to make in the film in the lower surface of the wing.

Puri should be flying again next week, assuming the weather decides to let me do some flying in November. Also, I have a new phone and I’m still trying to figure out how to connect it to the computer, so I’ve no pictures this week.

Change of Plan

I was planning to fly the Puri this morning. I spent the whole of yesterday putting the film back on so it could fly. Then I charged up the batteries and tested the motor wiring to see that it was spinning the prop in the correct direction. That’s how I discovered last night that the right elevon wasn’t working. I’m sure I tested everything out immediately after the mid-air collision two weeks ago, but it was an intermittent fault where the servo would “buzz”, I moved the stick to release it and it would move and seem OK for a bit, then jam up again.

Plan B called for charging up the Mustang batteries and flying that instead. Only, the weather had other ideas. The wind was 14 mph gusting to 27. Other than that it was a lovely bright, sunny morning, as I watched the clouds whizzing across the sky over my head. It all looked so serene from the window. At least it did until you opened the window and the wind hit you full in the face. There’s a point where you can “hear” the wind howling through the trees that you know deep down that not flying is the sensible decision.

Having put all the solarfilm onto the Puri so carefully yesterday, I now found myself cutting into it with a knife to get at the servo which is buried inside the wing and attached with hot melt glue. Great.

When I removed the servo from the rib, the top pulled off and I could see where the nylon output gear had shattered, so I will have to order a replacement tonight.

So, now I’ve got 7 batteries to discharge back to storage (2 Puri and 5 Mustang) and I’ve not done any flying at all today. It really hasn’t worked out all that well, so let’s hope the rest of November isn’t like this.