Flying the Sunbird

If you’ve been following my Sunbird series you’ll know that in the last posts I covered and finished the wing.

I had to run an errand after work which got me home a little earlier than I normally do. I immediately got into finish the glider mode. The ailerons setup was pretty easy, just like any other ARF. I setup and made mounts for the wing bolts and drilled the holes in the wing. Basically, I was done!

I had two OrangeRX receivers in my electronics box. Now, I’ve had a bunch of these receivers and have had no problems with them. They’re my normal go-to receiver for my park flyers. I have used them in my nitro planes without issue as well. It seems to me though that I’ve either hit a period of time where my gear is starting to need replacement or I’m in a streak of bad luck on components. I ordered an 8ch with satellites to put in my cheaper glider when I moved the nice Spektrum receiver to my P-38. It was DOA. The RX would bind, but after that no light and no function from the unit. HobbyKing set up an order for replacement but I’ve not seen the new unit. It’s been a few months so I’ve given up hope there.

I then ordered another 8ch RX and had been using it in the aforementioned glider and along in my uncle’s Sig Kadet. It had no problems. Now it too seems to have suffered the same issue as the other 8ch RX. For a long time I was running a 6ch DSM2 Orange RX in my P-51 Mustang. The last time I had it at the field it glitched all over the place in the air and I was lucky to get the plane down. I’m pretty sure I tossed that RX.

Anyhow, I had that 8ch and a 6ch in my box. I thought the 8ch was the good one, but on testing it didn’t do squat. I set it aside and got the 6ch. It bound and I got all the electronics hooked up and tested it all. Everything seemed great!

I initially thought I was going to use a 300mAh battery to power everything. I put the glider on my balancer and found that it was very, very tail heavy. I swapped out the ESC/UBEC to something heavier and swapped a much heavier 1000mAh battery. I still seemed tail heavy, but since there was no actual measurement listed for the CG I decided I’d throw it a couple of times from the side the retention pond/field where I fly behind our subdivision. It was a little more windy than I like for this kind of test. It looked as if a storm was going to come up. I gave it a toss and immediately saw that this plane was going to be a handful. After a couple of more tosses I decided that it was definitely too tail heavy.

Back on the workbench I took the wing off and decided to add the launch hook for the high start. I also decided to add one oz of lead to the top, forward most part of the canopy. After the glue was set enough for use I set to work putting together the high start.

Setting up the high start could be its own post about the level of frustration it gave me. I ended up getting a big knot in the nylon line and had to cut it out and splice the line back together. I was beginning to think that this was just a bad day. It still looked like the storm was moving in and I at least wanted to get back out and toss the glider a couple more times to check the CG and get at least one launch.

Anyhow, I finally got the high start together and it looked like the storm was going to end up missing us. The glue finally set enough to be OK to fly. Now I have the servos setup to be on their own channel. Taking the wing on and off means connecting and disconnecting the servo wires from the RX. On the first tosses I know I had full aileron control because it was a handful. On the second set of launches I didn’t know it at the time but I only connected one aileron correctly. However, the fixed CG made the glider much easier to fly and it had a nice glide.

After a couple of tosses I decided it was time to try my first ever high start launch. I set everything up and pulled it back about 10 to 15 paces. Not much at all. I let it go which put the glider into a flight that wasn’t much more powerful than a hand toss. It flew ok. I was doing a  lot of trim work. It just didn’t seem like it had the roll authority. My initial thought was that the lack of roll authority may just be because this glider had ailerons added as an after-though and that to control the plane it would be better to use the rudder.

On the next flight I decided to go to almost full power. I pulled it back 30 paces. That amount of pull put the glider up pretty nicely. I was able to do a lap around the field and land it without any major issues. The height was probably up there with some of my first DLG throws, about 50 or so feet. I got the plane back and did a second launch with about the same amount of tension. This time I used the elevator to put a zoom in near the end of the pull. I got a pretty good zoom, but stalled it. My setup was lacking elevator authority. I’m used to larger control surfaces so trying to get the nose over at the top of a climb where the plane is dramatically slowing down would take some getting used to.

I did a couple more launches for about 4 or so on the high start. The last two I pulled back to about 40-45 paces. They got some good height and I was able to do much better at the zoom without stalling (too bad). On one launch and zoom I even got to hear that nice rushing woosh sound that those big unlimited gliders seem to produce tons of when they’re coming off the winch line! At this point I also was getting all the trims pretty much where the glider wouldn’t fight me the entire flight. It still required more input than what I like in a glider, but I built it so who knows what kind of junk I introduced!

After a flight I was messing with the sticks on the transmitter and noticed that I didn’t have any movement from the left aileron. Well, there was the reason for junk roll authority. I popped open the canopy, disconnected the battery and went about looking for the issue. I ended up putting the left aileron into the throttle channel of the RX. My DX18 doesn’t use the throttle channel for a “sailplane type” model so it was just set to neutral. Shaking my head at my luck I put the plug in the right channel. I plugged the power back in and put the canopy back on. Picking up my radio I did a check of the control surfaces and saw that everything was in order!

I pulled some off my roll trims as I knew that it was going to not need nearly as much. I then picked up the plane and started back for a good hard launch. At about 45 paces I let the plane go and immediately gave it a tad bit of up elevator to climb up on the launch. Just a sec after I let go and pointed the nose up for the climb the plane started rolling to the right. This was the same direction that I had been trying to get trimmed out during the earlier flights. I started to ease the stick to the left to counter this action. I didn’t see any appreciable difference in the planes track.

By now the plane was about halfway down the launch and about the 1/3 to 1/2 it’s launch height. It seemed like it still had the same elevator setting as it was headed up. Not as much as I wanted, but giving it more input on the elevator didn’t seem like it was doing much. The plane continued it’s right roll much to my dismay.

At the top of the launch I knew something was very wrong. Normally where I nose over into a slight dive to start the plane was rolled too much on its side so my mind switched to just getting it off the launch line. It came off and was about on its side with the nose level with the horizon. I was concerned to say the least. I switch from trying to correct the roll to giving it full deflection to the right in order to now hopefully complete the roll and then slow it down as it righted itself. Nothing. No response to the inputs from the glider. It was now nosed over and into a dive. Frantically I was giving it full elevator input, just trying to get it to hopefully pull out before the ground.

No. Such. Luck.

The Sunbird's first crash. Oops.

The Sunbird’s first crash. Oops.

The crash could have been much worse. Luckily the large amount of rain we had in the days up to my flight made the ground extra soft. As you can see from the dirty nose in the picture the plane landed straight in. It actually looked like a rather large, sad lawn dart. It made such a sickening thud noise followed by a crack. I’m actually surprised my shoddy construction didn’t fail in more places. The wing broke exactly at the outer panel. You wouldn’t know it by looking at the build instructions but there was supposed to be a dihedral brace that connects the outer panels to the inner ones. I didn’t see this in the instructions so I didn’t add it. Well it broke right at that joint because the strength there was just CA.

What caused it? Well, remember the whole diatribe about Orange RX’s? It turns out that I didn’t throw out that crappy 6ch receiver that was giving my P-51 troubles. As I walked up the glider I was wiggling the sticks and watching the rudder and elevator. There was no movement. My initial thought was that I forgot to plug the battery into the ESC. I then remembered that yes, I did plug the power in because I checked flight surface movement before I pulled the glider back on the line.

As I got closer I kept wiggling the sticks. At about 20 or so feet I saw the ailerons start responding. “Interference,” I thought! I got right up to the glider and the ailerons stopped working. I kept wiggling the sticks. They came back and then started stuttering. Then out. Then they worked. And so on.

With a sigh I rolled up the high start and took the plane back to the garage. I haven’t thrown those RX’s away yet. I haven’t been to the shooting range in some time. They’d probably make great targets for my .22!

About Mike

I'm a software engineer. Look into the about page for more information about me.
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