Sleet, Snow, Freezing Rain and Ice

It was another week when I’ve been grounded by the weather. This time a front of warm air met the freezing -5 air that’s given us snow during the week, resulting in it raining all day. Not just ordinary rain, but it was freezing on hitting the cold area already over us, leading to ice forming on the roads where it fell. I didn’t fancy either freezing, getting wet or sliding around on a bike, so flying was out of the question.

I am feeling quite pleased with myself because I’ve finally figured out how to make interrupts work on the BBC Micro:Bit, so I’ve now got PWM speed control working properly. All my testing so far has been using the motors controlled from a software timing loop to create the mark to space ratio needed to control the motor speed. This is really bad as the reading of the sensors and computation of the PID equations was causing all sorts of chaos to happen with the motor speed. Using an interrupt service routine means that all the motor speed control happens in the background and the foreground code can simply worry about reading the sensors and updating the motor speed to keep the aircraft stable. As you can see in the picture, it’s still on the test rig which constrains any movement to just the roll axis. My Christmas project is to finally make it fly. It’s certainly been a challenge.

The other thing that I’m quite pleased about is that I’m now a lot nearer to getting the wings to fit on my Dimension plane. Those centre pieces just need to be glued in place with a suitable spar and I’ve got a plane with wings. However, I would like to check the incidence angle first, and that means I need the wing polars. It uses foam wings with a strange profile, so I’m either going to have to put the profile through Xfoil to get the polars, or I’m going to have to make an educated guess. It looks a lot like a Clark Y, but I’ve never liked guessing. That’s my other Christmas project, as getting some results out of Xfoil would make me very happy.

I might not have managed to do any real flying this week, but I had a go with the simulator this morning instead, just to make sure I can still do it. I think that’s it for this year, as next week is Christmas day and the week after is New Year’s day. I’ve also got some time off work, so I’m planning on doing some building. If that results in something that actually flies, then I’ll be very happy. I don’t care what it is, it just has to fly, and I’ve got a number of ideas in my head as to what to build.

Foggy

This week I was excited at the prospect of having a proper flight with my new PowerUp4.0 paper plane as the wind forecast was only 3 mph. However, we all know that lack of wind at this time of year often brings foggy conditions and that’s how we ended up this morning. There are trees that you can’t see in the background of the picture above. So here I am all charged up and nowhere to fly again.

I have actually been doing some building today as, recently, I’ve been a bit stuck on the problem of how to attach the wings on my Dimension profile aerobat. During today’s downtime I’ve also been reading my RCM&E, which contained a description of some new F3A designs. The interesting thing is that they gave flying weights and wing areas, so I was able to work out that an F3A plane has a wing loading of about 43g/dm2. Strangely enough, that’s almost exactly what I’m predicting for the Dimension, so maybe I’m not that far off having something that will actually fly quite well? If only I could figure out how to stop the wings wobbling and falling off. I may just have had a genius idea, but I’ve been there before. At this point I just need to fix the wings on and cover it, even it if does look like an ugly hack.

To tell the truth, I actually didn’t mind not going out on the bike today. It’s absolutely freezing out there, or about minus 2 at least. Flying a computer seems the better option at this point.

First Flight: PowerUp 4.0 Invader

This is a bit different. I had my first flights with a Power Up 4.0 Invader paper plane today. The weather was rather against it, though, and in all honesty I should have waited for a day with no wind. But I just had to give it a go.

It was a day when it looked like the Sun just hadn’t bothered getting out of bed. It was doubtful whether I was going to fly the Mustang today, as the forecast was for 10mph winds, it was cold, dark, gloomy and there was a threat of rain. In the event, I decided to go anyway and bumped into a friend of mine at the field with his Multiplex Cub. I’m obviously not the only crazy one and we also had three other people turn up with drones during the morning.

So, back to the Invader paper plane and by this point it’s blowing a gale. I know I shouldn’t fly it, but I’m here and I’m quite sure I’m going to end up chasing it downwind. I just want to test how controllable it is.

Flight one, the two video cameras are setup and I launch it into wind. It climbs up into the sky, does a big loop over my head and over the cameras and heads downwind. At this point I’m trying to control it by tilting the phone while my thumb controls the throttle by sliding a control up and down. I manage to turn back into wind, cut the power and let it glide back down to earth. It definitely flies!

There she goes, up, up and away. That’s actually the second flight as the first flight completely missed both the wide angle cameras I had set up as it climbed out so fast. This was followed by me having a light jog downwind to retrieve the errant plane as any penetration into the wind was impossible. Then I accepted the inevitable and turned the cameras downwind and had a few more flights until we deemed it absolutely crazy windy. That’s when I got the Mustang out.

The Invader actually looks like it could be a lot of fun in calm conditions. The real problem here was the lack of pitch control. I’m not even sure I was banking correctly as I discovered that there are two thumb controls on the App, one for throttle and the other for rudder. The rudder is a differential control of the two motors. I was trying to tilt the phone to fly the plane, but then, on the later flights, I tried using the thumb control. Needless to say, in the gale force conditions, it was difficult to tell how much I was able to control the plane. What I had to do to get it to fly, rather than loop over my head, was to reduce the elevons from the 20 degree up which is recommended to a slightly down position as the wind was doing the job of creating all the lift it needed. This meant that the launches were more flat, but it still wouldn’t penetrate the wind at all. It is very impressive in that it would definitely fly and, after cutting the throttle, you could watch it glide back down to the ground relatively gently. Very impressive in the windy conditions.

There was a bit of a problem with the wind collapsing the wing structure, but I know we shouldn’t have been flying it in the conditions. Two bits of sellotape to fix the plastic wing spar to the paper partially fixed this.

In short, I need to wait for the right conditions, but it looks exciting. A bit between a free flight plane and single channel RC. You have throttle and rudder control and that’s about it.

As for the Mustang, I had my usual seven flights, but it was perishing cold on the fingers. One of my packs is definitely end of life, so it’s six flights a week from now on. As I had the camera gear set up anyway, I couldn’t resist filming my first flight.

This is how we land, almost right on top of the camera. The rest of the flight you really couldn’t see much of the aircraft as it’s so small. Even though I deliberately flew close in front of the camera none of the shots of the plane on the video really stand out. It was a day for just keeping the aircraft in the air and the gyro was needed because of the horrendous turbulence. I didn’t fly much gyro off and the aerobatics were very ragged. Time to go back home into the warm.

Let’s hope for some calm weather next week as I’m desperate to try out the Invader again. I’m going to watch some more videos of people flying it and I’ve also just discovered that FliteTest do a foam F22 body.