Sunday, January 26, 2014

Phase I completed

Over the weekend I took a moment to install the Kroger Sunshade to get out of the searing sun, at least some of the flight time.

This sunshade is very effective and super light-weight, so it's a no-brainer in my book.

On Saturday and Sunday I collected some more climb data and various airspeed data to compare against the GPS groundspeed by eliminating the wind factor.
The toughest was the 50kt box as the plane is close to stall and not very maneuverable without getting completely out of balance. It took me a while but I was able to collect some good data.

After the duties flight testing were completed I went back up to 6500 feet and took some more photos of the beautiful winter scenery around Tucson.

Then I headed out West to Silverbell Mine.

On the way I took a shot of my home airport, KAVQ, from the North.

And on the way back from the mine I passed my old home field where I trained for my Sport Pilot license and where I had my Rans S-12S stationed for a while, 4AZ8, The Ultralight Strip.

All in all a very nice and relaxed flight to finish off Phase I. The plane is very easy to fly and has absolutely no surprising characteristics. The next weekends should be fun when I can finally leave the 25nm radius around KAVQ.

After landing and hangaring the plane, I made the important Phase-I-completed logbook entry and removed the 5-gallon water ballast tank from the passenger seat.

The seat is now available for human passengers if they so please to come along with me.

3.75 years after pulling the first rivet on a pile of aluminum sheet metal, I am sitting in this contraption and am flying around in it.

Absolutely amazing!

Would I do it again?

You bet, I would!

Monday, January 20, 2014

Grounded by the Flu

I have just been made aware of the fact that although it looked like I was in full flow with the flight testing procedures the postings here suddenly stopped coming.
Well, the reason - as the title strongly suggests - was not at all voluntary silence but a bad case of the flu (yes, I did get the flu shot in November).
Yesterday, I had just been out at the hangar again and the first time for what appears to have been two weeks.

During my unplanned hiatus I was busy getting a canopy seal kit from Van's as well as a glareshield. The glareshield fits perfectly without any trimming and smoothly aligns with the canopy frame without too much clamping force needed. I will try to complete the surface preparation during this week, so I can spray the paint on the weekend and then install it when the paint has cured. I still have quite an amount of the Dupont Flat Black that I used for the instrument panel. If that turned out to be not "flat" enough, I could always cover the top with fabric later on.

I was also getting ready to install the Kroeger sunshield yesterday but because of teh flu being rather tiring I did not feel up to the task of marking the center of the canopy for the correct alignment of the center slide of the sunshield. I just did not trust myself enough to do a good job in this condition, so I refrained from continuing the installation.

This will all have to wait till the next weekends but the good news is that I am feeling better every day and that there is only a bit more of climb data to be collected before I can sign her off.

Sunday, January 5, 2014

Climb Data Collected

Another take-off confirmed that the RPM indicator is still somewhat jumpy on take-off and initial climb-out. It seems to jump between two discrete values and is much more stable than before. Surprisingly enough, the indicator is rock solid as soon as the initial climb-out is done. Subsequent climb-outs work work just fine and show a constant RPM. I can absolutely live with this until I remove the cowl anyway for some other reason. Then I would try a 30K resistor instead of the 20K one and see if this would completely solve the problem.

I have also alleviated the roll problem by extending the pushrod for the right flaperon by one turn of the attached fitting. To get there I had to remove my split floor panel and squeeze my hand in there but it only took an hour to complete the task. If I ever have to open the floor panels again, I might add another half turn as there is still a very slight roll tendency left.

After doing this fix, I wanted to fly to confirm that the airframe was still balanced and to collect some climb data and do some speed boxes.

I did all that but the really impressive thing was the shot I took once I got to 9000 feet.

Both have been taken north of El Tiro Gliderport at about 9000 feet. Breath-taking!

Overall, the data suggests that my propeller is a bit too high in pitch. I was not able to get to 5500 RPM in straight and level flight at density altitude of 7500 feet.
So, I might have to do this before the next flight and then verify that I am doing better. By the way, the left EGT sensor was working ok during the flight and did not vary too much but after I had hangared the plane again and let it cool down the SV showed a cross in place of the left EGT temperature. That usually means that the sensor is dead or not connected. Oh well, there is always something, I guess ...

A New Problem

I went to the hangar early as I had to remove the upper cowl and work on the RPM wiring. When the cowl was off I could also verify that the electronic ignition modules had not been exposed to excessive heat so far (this will change in the summer, I suppose).

So far I have always opened the oil door soon after turning off the engine and left it open to allow the hot air to escape. I was also careful to get the cowl out of direct sunlight when the engine was hot. All this might have helped keeping the temps down a bit.

Concerning the RPM wiring, I had prepared a 20K Ohms resistor with spade connectors to allow it to be inserted and replaced if necessary. The following picture shows the wiring you would want to work on. The black wire is ground and the white/green one carries the signal (and would get spliced for the resistor).

I spliced the white/green wire and added spade connectors at its ends and inserted the resistor. The resistor is covered with shrink tubing that connects to the spade connectors in order to reduce stress and vibration (and dirt).

With this fix installed I did a ground engine run with the cowl still open. The RPM was steady within the limited range of RPM I could produce on the ground. The static WOT run showed 4920 on the first attempt and 5000 RPM on the second. I could only verify in the air if this resistor fixed the problem, so I put the upper cowl back on and took off.

During take-off and climb out I still experienced somewhat jump RPM readings but as bad as it used to be. After throttling back the RPM was rock solid and I continued flying around 5300 for a few minutes before I leveled off and let the autopilot take over to maintain altitude. I open up the throttle to maximum again and saw steady 5520 RPM. I even descended a few thousand feet after this and did another WOT climb at 75 knots without any jump RPM readings.

I will see today if this fix solved the problem completely when taking off again and doing the climb rate evaluation test (which requires extended WOT climbs) and the speed test box at 5500 RPM.

Now what is the new problem? During the ground run with the cowl open and the subsequent flight I experienced very jumpy and fluctuating readings in the left EGT sensor. The right one was rock solid but the left one almost never settled and even dropped off the SkyView a few times. This might indicate that the sensor is dying or the wiring has broken. Thankfully, this sensor has practically no value as its only real use would be during mixture changes of the engine but the Rotax does not allow for manual mixture changes. I will watch this for a while and then decide if and what to do about it. This is certainly nothing that would keep me from completing the test phase.