Wednesday, April 15, 2009

Leaving the nest

The weather was the best around here in months, and I took advantage of it! I flew for 2.5 hours, my longest flight yet in Phoenix, my little Challenger II LSA. I landed at 4 different airports, and it was the first time I re-fueled away from home, and then continued the trip. At least, in this incarnation!

I have been keeping track of the fuel burn since I decreased the prop pitch. I originally set my cruise rpm at 6400-6500 with the new pitch, and got a burn of 3.6 gph. About what I got before with full throttle cruise, around 6200-6300 rpm. The last two tanks, I increased to 6500-6600 rpm, got a few extra mph, and increased fuel burn to 3.8 gph. Certainly not a crushing penalty! I’ll be bumping that up to 6600- 6700 rpm, and see what happens with that. There were a couple of cases during the flight where I was very happy for the increased climb capability of the decreased pitch.

Since the wind was fairly calm, I decided to go over the mountains into the Tahoe basin, fly across it, and then land at Truckee airport. When I went through Spooner pass, it was tempting to fly straight across the water to Brockway pass, but I was spooked about the prospect of flying 10 miles over water. In retrospect, since I was 2200 ft above lake level, I probably could have made it to shore at any point with an engine failure, but I wanted to fly over my house and take a picture anyhow, which I did. There are enough beaches around the lake that it would have worked at any point, but I didn’t quite realize how big a fraction of the Tahoe shoreline is just big rocks!

I tuned in the Truckee AWOS (first time I’ve used that in this incarnation), and while the normal runway is 28, the winds, still moderate but higher than at Carson City, were favoring runway 19. It’s shorter than 28, but at 4600 ft, “short” is relative! When I switched to the CTAF, the place was a complete zoo. Someone was waiting to take off from runway 28---waiting for a plane that was taking off from runway 10! They may both have had headwinds. That kind of thing happens out here with some regularity.

One thing happened that was a little weird. The pilot on 28 deferred to the one taking off on 10, and I was just getting ready to turn base for 19. I told her I didn’t need much runway, and wouldn’t get to the intersection with 28, and that I’d report stopped, and she said that was fine. I stopped and made the call, but she couldn’t hear me! But I could hear her. She kept asking if I was down. Unicom said they saw me stop, but they couldn’t hear me either. I could hear them fine. In the air they could all hear me fine. The radio worked fine for the rest of the day.

Truckee is at 5900 ft elevation, and the relevant mountain pass is somewhat closer than it is from Carson City. So, I decided to give the climb performance a more difficult test, and headed straight for the pass. There was a great alternate landing site about halfway up (ski resort parking lot!), so I had that covered. By the time I crossed the 7200 ft pass, I was only at 8000 ft. Not awful, but less than I wanted. Still, a good test!

I am definitely noticing a difference with the engine temps with the lower prop pitch/higher rpms. The EGTs are both higher. They had been running around 950, and now they typically run 1000-1050. But, on descent, I need to watch to make sure they don’t overtemp when I reduce power. It never used to do that, but I was never making descents from 8500+ft before, so I don’t really know the cause. When they brush up against 1200, they drop immediately with a substantial power reduction, and then I increase the power until I find a stable setting. As I get used to it, I’ll probably get to the point where I just set it right on initial descent---but I’m not there yet.

The CHTs went up only very slightly with the pitch decrease/rpm increase, but now one of them is acting flakey. It will be cruising along at 210-225, and then all of a sudden, drop down to 125-150, and bounce around there for a while. Eventually, it will go back to 210-225. Is it even possible from a physics standpoint that the cylinder head could cool that much that fast, and then wobble around? There’s no discernible change in engine power or sound, and the EGT remains stable. My guess is that this is a gauge problem, maybe caused by additional vibration from operating at a consistently higher rpm? Thoughts appreciated!

After clawing my way back in to the Tahoe basin, I was once again tempted to go over water to Spooner pass on the other side. But, there was another pass visible that I had never noticed before, which was a much more direct route home. I looked at the chart, but I couldn’t get a clear sense of the elevation of that pass (no road), so I stuck with my original route. I did climb up to 9500 ft for the first time, and at that altitude I’m sure I would have made the other route. Maybe next time. 9500 ft sure didn’t look very high, since most of the ridgeline I was flying next to was barely below that. Definitely still climbing, though. At 9500 ft as a realistic altitude, I can definitely get to pretty much everywhere around here, without excessive diversion to find lower terrain.

Over Spooner pass, I considered turning north to go home since I had gotten a late start, but decided to continue, so I turned south toward Minden airport to get fuel. Just when I was getting ready to turn base, I heard a King Air call in on downwind behind me. I told him I’d try to clear the runway quickly, and he came back with a cheery “No worries!” Still, I landed a good ways down from the threshold to minimize ground time, and didn’t roll more than a few hundred feet before making the turnoff. After getting them adjusted at the annual, the brakes work GREAT.

What’s amazing about this is that a radio isn’t legally required for any of these airports! They are all uncontrolled fields. I don’t think I’d feel at all comfortable flying around in this beehive completely out of comm, legal though it would be. On the other hand, I *LIKE* the fact that this is a very active GA area, with everything from gliders, trikes, and powered parachutes, through Citations and King Airs, and everything in between.

After refueling, I took off for Alpine County airport. It’s pretty much in the middle of nowhere, at the bottom of the Carson Valley, just before the Sierra Nevada mountains start to rise sharply. The normal pattern is right traffic for runway 35, so I set that up, and landed without incident---until I noticed once on the ground that I had landed slightly downwind! Hadn’t done that in a long time. I hadn’t spotted the windsock from the pattern. I had originally intended just a touch and go, but it didn’t feel quite right, and that was why. So, I made a full stop, taxied down to the end of runway 17, and took off. I lifted off quickly, but I wasn’t happy with the climb rate given the rising terrain in front of me. Runway 17 points toward some very high terrain, even though there is a sharp drop off at the end of the runway, leading down to a valley before the mountains start in earnest. I thought about turning to follow a canyon, until I realized I wasn’t sure which way the water was flowing. So, I did a steep 180 instead, and headed north toward home, with a new respect for how tightly that little CWS can turn around!

On the flight back, I noticed a slight vibration, sort of a flutter. I’ve noticed this before, but then it goes away. It only seems to happen at certain combinations of airspeed and rpm, but not consistently, and I haven’t been able to characterize it. It may be related to being slightly uncoordinated; I guess I haven’t fully internalized the additional rudder needed with the doors on yet, since I noticed the ball off center a couple of times. It doesn’t feel like it’s the engine itself, which still seems smooth, and I don’t feel it in the stick or rudder. It’s not severe, but it’s distracting. Anybody have any idea what this might be?

By the time I got back to Carson City, I was tired, cramped, and stiff. If I’m going to fly any distance in the little beast regularly, I am going to DEFINITELY need to get better seats. More weight---Hoorah! Not the tightest pattern I’ve ever done, and I bounced the landing. Not a BIG bounce, mind you, and it was on the mains, but still---

I’m a big believer in silly milestones, and with this flight, over 10% of the total flight time Phoenix has is mine, 32 out of 311 hours.

Overall, just an AWESOME day!



No comments:

Post a Comment