RVbySDI
Well Known Member
Below is my raw data from this weekend. My mission this past weekend was to see if I can calibrate my GRT HX and EIS4000 Fuel Flow functionality so that it will return a reliable and accurate reading. After some measure of "tweaking" I am feeling more comfortable with my fuel readout on the Totalizer (sp?). I don't think I have the R&L Quantity readings calibrated well yet so I have been relying on the Fuel Flow to keep track of my fuel burn.
For the length of time with my Phase I flying I have not been able to trust what the instrument was telling me on the fuel flow. It appeared I was always putting more fuel into the airplane than what the instrument was telling me I should have needed. This was very disconcerting since the instrument was showing I had more fuel in the airplane than I actually did. It doesn't take a rocket scientist to know that scenario is not good. No offense to any rocket scientists here on the forum.
Well, anyway, after a lot of flying and fueling up and recalibrating I think I have the Fuel Flow readout much closer to the actual fuel burn. I think it might still need a little bit of tweaking but I feel much more confident in its readings. The raw data below is of 8 different readings (but not necessarily 8 different flights) in which I was working on figuring out the actual fuel burn of my airplane.
The data is also showing the results of my first attempts to run LOP. Having never done so I was a little nervous about what exactly I needed to be doing and observing while running lean of peak. I must admit the GRT HX makes running LOP very simple. The engine monitor has a LEAN button for this purpose. Without going into the boring details I basically set up for straight and level cruise. When I have altitude, airspeed, etc. stabilized I push the LEAN button. Then begin leaning the mixture. Once the EGT's peak the temperature numbers for each cylinder's EGT changes to a negative number to represent that cylinders temperature below the peak. From then on I simply dial in the mixture paying attention to the last cylinder to peak. It is really very easy to monitor.
If you notice the CHT temps and the EGT temps in the data below you can see they are both very stable and the span is very tight from one cylinder to the next. All cylinders operated in lock step very nicely. When I compare the temperatures running in this configuration to the time I have been flying without leaning like this the temperatures are quite a bit cooler. In my normal operations without attempting to run LOP I have been seeing EGT's in the 1400-1450 range and CHT's in the 380-410 range. Compared to these temps the LOP temps are considerably lower.
The last two flights of the weekend I made some specific changes to my flying that may have answered my questions concerning fuel burn. I climbed to altitude on the left tank only. Once at altitude (I tried to fly at 8000' DALT as much as possible) I stabilized the airplane at around 65% power, set the autopilot and switched my tank to the Right tank. At this point I started leaning using the GRT LEAN function. Once there I flew for exactly one hour on the right tank. Once the hour was up I switched back to the left tank. I descended and landed for fuel. I immediately filled up the tanks to the neck and recorded the fuel used.
Both times I put 6.5 gallons in the right tank. If you notice the FF reading on my GRT was showing 6.7 (A note on this. These FF # are an estimation as it tended to fluctuate some. As an example, during the last two flights the FF ranged from 6.7-7.1.). I think I might be able to tweak the EIS4000 a tad more and get the readout spot on. However, I feel pretty good at this point about the readout. It is very close now.
I would welcome anyone's analysis of my numbers. Also, I input all my data in an Excel spreadsheet and have some descent graphs of EGT, CHT temps, etc. but I could not figure out how to get the graphs to display in the forum. If anyone knows how to insert these Excel graphs please let me know how to do that and I can post them.
Date 9/17/2010 9/18/2010 9/18/2010 9/18/2010 9/18/2010 9/19/2010 9/19/2010 9/19/2010
Time 18:00 8:00 10:15 10:30 12:45 10:15 12:27 13:00
Start Time :07 :05 :05 :20 :09 :08 :09 :39
Stop Time :37 :20 :20 :35 :54 1:08 :39 1:09
Duration 0.5 0.25 0.25 0.25 0.75 1 0.5 1
% HP 69 65 50 50 65 65 65 65
RPM 2300 2290 2120 2200 2300 2300 2300 2300
MP 22.7 22.5 17.2 18.5 21.3 21.5 22.6 22.6
HDG 280 281 355 355 165 330 247 81
IAS 125 130 114 119 121 124 124 124
TAS 136 142 129 134 140 141 142 141
GS 147 142 145 149 132 165 136 145
FF 7.4 7.6 7.3 8.2 7.6 6.7 6.7 6.7
MPG 19.6 18 20 18 18 20 20 20.8
DALT 6227 6233 8160 8157 9200 8027 8064 7112
LOP -50 -50 -53 -53 -35 -20 -29 -29
OAT 72 72 65 65 59 65 65 68
EGT1 1372 1388 1297 1286 1359 1362 1377 1359
EGT2 1360 1379 1298 1282 1341 1354 1368 1357
EGT3 1382 1392 1314 1299 1341 1364 1377 1360
EGT4 1374 1386 1302 1297 1346 1362 1374 1360
CHT1 342 331 327 341 320 325 319 315
CHT2 337 329 327 342 314 320 315 309
CHT3 328 320 322 337 311 314 309 306
CHT4 326 319 319 335 306 314 308 303
For the length of time with my Phase I flying I have not been able to trust what the instrument was telling me on the fuel flow. It appeared I was always putting more fuel into the airplane than what the instrument was telling me I should have needed. This was very disconcerting since the instrument was showing I had more fuel in the airplane than I actually did. It doesn't take a rocket scientist to know that scenario is not good. No offense to any rocket scientists here on the forum.
Well, anyway, after a lot of flying and fueling up and recalibrating I think I have the Fuel Flow readout much closer to the actual fuel burn. I think it might still need a little bit of tweaking but I feel much more confident in its readings. The raw data below is of 8 different readings (but not necessarily 8 different flights) in which I was working on figuring out the actual fuel burn of my airplane.
The data is also showing the results of my first attempts to run LOP. Having never done so I was a little nervous about what exactly I needed to be doing and observing while running lean of peak. I must admit the GRT HX makes running LOP very simple. The engine monitor has a LEAN button for this purpose. Without going into the boring details I basically set up for straight and level cruise. When I have altitude, airspeed, etc. stabilized I push the LEAN button. Then begin leaning the mixture. Once the EGT's peak the temperature numbers for each cylinder's EGT changes to a negative number to represent that cylinders temperature below the peak. From then on I simply dial in the mixture paying attention to the last cylinder to peak. It is really very easy to monitor.
If you notice the CHT temps and the EGT temps in the data below you can see they are both very stable and the span is very tight from one cylinder to the next. All cylinders operated in lock step very nicely. When I compare the temperatures running in this configuration to the time I have been flying without leaning like this the temperatures are quite a bit cooler. In my normal operations without attempting to run LOP I have been seeing EGT's in the 1400-1450 range and CHT's in the 380-410 range. Compared to these temps the LOP temps are considerably lower.
The last two flights of the weekend I made some specific changes to my flying that may have answered my questions concerning fuel burn. I climbed to altitude on the left tank only. Once at altitude (I tried to fly at 8000' DALT as much as possible) I stabilized the airplane at around 65% power, set the autopilot and switched my tank to the Right tank. At this point I started leaning using the GRT LEAN function. Once there I flew for exactly one hour on the right tank. Once the hour was up I switched back to the left tank. I descended and landed for fuel. I immediately filled up the tanks to the neck and recorded the fuel used.
Both times I put 6.5 gallons in the right tank. If you notice the FF reading on my GRT was showing 6.7 (A note on this. These FF # are an estimation as it tended to fluctuate some. As an example, during the last two flights the FF ranged from 6.7-7.1.). I think I might be able to tweak the EIS4000 a tad more and get the readout spot on. However, I feel pretty good at this point about the readout. It is very close now.
I would welcome anyone's analysis of my numbers. Also, I input all my data in an Excel spreadsheet and have some descent graphs of EGT, CHT temps, etc. but I could not figure out how to get the graphs to display in the forum. If anyone knows how to insert these Excel graphs please let me know how to do that and I can post them.
Date 9/17/2010 9/18/2010 9/18/2010 9/18/2010 9/18/2010 9/19/2010 9/19/2010 9/19/2010
Time 18:00 8:00 10:15 10:30 12:45 10:15 12:27 13:00
Start Time :07 :05 :05 :20 :09 :08 :09 :39
Stop Time :37 :20 :20 :35 :54 1:08 :39 1:09
Duration 0.5 0.25 0.25 0.25 0.75 1 0.5 1
% HP 69 65 50 50 65 65 65 65
RPM 2300 2290 2120 2200 2300 2300 2300 2300
MP 22.7 22.5 17.2 18.5 21.3 21.5 22.6 22.6
HDG 280 281 355 355 165 330 247 81
IAS 125 130 114 119 121 124 124 124
TAS 136 142 129 134 140 141 142 141
GS 147 142 145 149 132 165 136 145
FF 7.4 7.6 7.3 8.2 7.6 6.7 6.7 6.7
MPG 19.6 18 20 18 18 20 20 20.8
DALT 6227 6233 8160 8157 9200 8027 8064 7112
LOP -50 -50 -53 -53 -35 -20 -29 -29
OAT 72 72 65 65 59 65 65 68
EGT1 1372 1388 1297 1286 1359 1362 1377 1359
EGT2 1360 1379 1298 1282 1341 1354 1368 1357
EGT3 1382 1392 1314 1299 1341 1364 1377 1360
EGT4 1374 1386 1302 1297 1346 1362 1374 1360
CHT1 342 331 327 341 320 325 319 315
CHT2 337 329 327 342 314 320 315 309
CHT3 328 320 322 337 311 314 309 306
CHT4 326 319 319 335 306 314 308 303
