|Fligths 28 - 34|
28 11 Dec 04
1692lbs 101.9" 2.4 hrs
Since the last flight I repaired the 3rd crack in the surge tank. This time I ground out the area where the crack keeps reappearing and had it rewelded plus the entire adjacent joint to the bracket and the other side of the tank similarly. I also mounted the tank on rubber gromets to isolate some of the vibration. While I was at it I moved the outlet of the surge tank that feeds the cabin heater. This was on the top of the surge tank which could have allowed vapor to enter the cabin heater and then go directly to the intake of the pump. There was no indication that this had happened but just in case. The cooling on the flight was pretty much along the lines of Flt. 27 except today the OAT at 5500' was 70 deg. So, both oil and water temps were about 30 deg hotter, teetering on the oil limit. The A/S cal shows a more or less linear change in correction such that the indicator reads 3kts low at 70 and 5 knots high at 150. I split the flight in 2 parts. After the first part, I landed at French Valley for lunch and fuel. I added 30 gal putting me at 40 gal on board and 1830 lbs. Takeoff was much longer and climbout was dismal. I definately need to get that prop repitched before I do any testing over 1850 and stay at Chino with the 5000' runway.
Flt 29 13 Dec 04 1785 lbs 101.9" 1.5 hrs
I repeated some of the airspeed points from the last flight since I had neglected to fly some points. The data is puzzling. The A/S indication is about 3 kts low at 70 kias and about 4.5 kts high at 150 kias and linear in between. The data in in the Perfomance spread sheet on the "Data" page. If the error were in the static, I would expect it to be consistently high or low but not vary with AOA. I could see the total side varying with AOA but the way mine is mounted, I would expect if anything the error to be high at high AOA (70 kias) and low at low AOA (150 kias). My pitot is mounted above the nose and aft about 8-10". It is angled to be parallel to the local surface. Well I suppose +/- 4 kts is not so bad. On the cooling front, the flight was pretty good. The OAT at 5500' alt was 67 deg, only 3 deg cooler than flt 28. The coolant temp was always good but the oil was flirting with 230-240 deg and seemed to climb toward the end of the flight. I need to measure the delta P across the oil cooler to see if I need a bigger cooler or if I'm not getting good pressure in from the scoop. But honestly I have a bad case of get home-itis. It's only 7.2 hrs on the hobbs before I have my 40 hrs. I can tweek the cooling and repitch the prop at home. I'll need to re do my performance data with the prop change anyway. I've been at Chino now for 8 months! It is 100 miles round trip each time I go plus the hangar out there is an extra $500/mo. It's time to come home. I should have the 40 hours before New Years day and plan to come home to Compton on Jan 14th..
Flt 30 17 Dec 04 1719 lbs 101.8" 0.9 hrs
I got a takeoff data point (2059') but that is about it on this flight. OAT at 5500' was 61 deg and I had no cooling issues. I turned off the alternator to see if it had any influence on the oil temp and others. It had no effect. There was too much wind to do the repeat A/S cal points I wanted so I just enjoyed the clear air and flew until sunset.
Flt 31 21 Dec 04 1839 lbs 101.8" 1.6 hrs
The heavy weight takeoff was only slightly longer than earlier flights. Climb was about the same too. All the temps were fine. I spent about 30 min. at higher powers (4900 RPM) and had IAS of over 150 kts. I used my MP3 player for the first time. It works great. It was too windy again for the A/S cal so I just built some time.
Flt 32 24 Dec 04 1743 lbs 101.8" 3.0 hrs
It was another beautiful clear winter day but too windy for airspeed calibration. I flew to Borrego springs thru Banning pass. I stopped at Ramona to check on my old hangar mates but no one was there. Then back to Borrego for lunch and fuel. After fueling I was up to 1791 lbs. Even though Borrego is near sea level the climb off the runway was extremly weak. With this prop it has very low climb rates below 120kias.
Flt 33 26 Dec 04 1826 lbs 101.8" 3.0 hrs
The weather was overcast but it was up at about 7-8,000'. Rain was expected but the weather stayed constant for this flight. The takeoff sucked, just like at Borrego. Makes sense since I was 34lbs heavier. I've been debating on whether to send in the prop for repitch or wait till after I modify the exhaust and put on the spinner. I'm now thinking that I'll just buy a second prop. This will speed up the process of getting the new prop. After talking to Don at Sensenich, he says I will get 200RPM at level power for each inch I change the pitch. I'm now getting 1946 static and 2676 at top speed (5500' at 160kias). I can go up to 2919 before I reach engine limit. So thats and increase of 243RPM. He says it is easier to recarve to a flatter pitch so I want to err on the side of too much pitch. Also I expect as I change the exhaust, intake duct and put on the spinner and other clean ups, I will get a few more RPMs at the high end. So I ordered a 70"x86" prop. This is 3" less pitch. So, in the same configuration I should get 150RPM more at the high end. That should give me 2826 RPM or 5228 on the engine. At the low end the pitch change at constant torque would give me 1976+150 or 2126. I believe because the torque curve is steep at that RPM, I will get about another 150 due to the torque increase. So I should be looking at 2276 (4210 engine). After I get some data on that prop I can repitch both to get a more optimum on both props. This way, I'll always have a spare in case I need it and not be down waiting for the prop changes. The wind was down today, so I did get to redo the airspeed points and I ran repeat speed/power points. The data laid on top of the flight 27 data. Nice to have some consistancy. The airspeed cal had considerable scatter but still showed the same trend as before. I now have more than 40 hours on the hobbs but my actual flight time is 37.8 hrs. I need only 2.2 more to complete my 40 hours!
Flt 34 1 Jan 05 1796 lbs 101.5" 0.8 hrs
With 41.4 hours on the hobbs, I was able to fly my very supportive wife for the first passenger ride! The weather cooperated just enough to make the short flight over to French Valley (F70) where we met about 19 other EAA chapter 96 flyers. The airplane handled great with Vilma on board. That's no surprize since I've been at this weight and CG many times. In fact the climb performance was quite good. I suppose the cold weather helped that a bit. The only squawk was that the #2 radio joined the #1 and they both are weak and garblaled on transmission. I had to use my handheld to reach Chino tower on the return trip. I'll be taking it in to the avionics shop before I return to Compton airport. I should be heading home Jan 14th, Wahoooooo!