---------------------------------------------------------- KIS-List Digest Archive --- Total Messages Posted Wed 10/23/13: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:16 PM - Re: KIS-List Digest: 1 Msgs - 10/21/13 (SUSAN TRICKEL) 2. 04:16 PM - Re: KIS-List Digest: 1 Msgs - 10/21/13 (SUSAN TRICKEL) ________________________________ Message 1 _____________________________________ Time: 04:16:38 PM PST US From: SUSAN TRICKEL Subject: KIS-List: Re: KIS-List Digest: 1 Msgs - 10/21/13 =0A =0A=0A________________________________=0A From: KIS-List Digest Server =0ATo: KIS-List Digest List =0ASent: Tuesday, October 22, 2013 3:00 AM=0ASubject: KIS-List Dig est: 1 Msgs - 10/21/13=0A =0A=0A*=0A=0A=========== ===============0A- Online Versions of Today' s List Digest Archive=0A================= =========0A=0AToday's complete KIS-List Digest can also be found in either of the =0Atwo Web Links listed below.- The .html file inc ludes the Digest formatted =0Ain HTML for viewing with a web browser and fe atures Hyperlinked Indexes =0Aand Message Navigation.- The .txt file incl udes the plain ASCII version =0Aof the KIS-List Digest and can be viewed wi th a generic text editor =0Asuch as Notepad or with a web browser. =0A=0AHT ML Version:=0A=0A- - http://www.matronics.com/digest/digestview.php?Sty le=82701&View=html&Chapter 13-10-21&Archive=KIS=0A=0AText Version :=0A=0A- - http://www.matronics.com/digest/digestview.php?Style=82701 &View=txt&Chapter 13-10-21&Archive=KIS=0A=0A=0A====== ==================0A- EMail Version of Today's List Digest Archive=0A============== ==========0A=0A=0A- - - - - ------------------ ----------------------------------------=0A- - - - - - - - - - - - - KIS-List Digest Archive=0A- - - - - - - - - - - - - - - - - - - ---=0A- - - - - - - - - - Total Messages Posted Mon 10/21/13: 1=0A- - - - - ----------------------------------------------------------=0A=0A =0AToday's Message Index:=0A----------------------=0A=0A- - 1. 11:04 P M - TAS Error with my new EFIS- (Galin Hernandez)=0A=0A=0A=0A____________ ____________________- Message 1- _____________________________________ =0A=0A=0ATime: 11:04:20 PM PST US=0AFrom: Galin Hernandez =0ASubject: KIS-List: TAS Error with my new EFIS=0A=0APardon the long wr ite-up.=0A=0AAfter buying my airplane several years ago I did a series of m aneuvers at=0Adifferent power settings and, by using GPS groundspeeds, I ma de a fairly=0Aaccurate calibrated airspeed chart. For the next few years I used the CAS=0Achart often and found that, at normal power settings, I cons istently=0Acruised at 143KTAS.=0A=0A=0AFast forward to this year when I ins talled a complete DYNON Skyview EFIS=0Asystem which automatically calculate s TAS. But, at normal cruise power=0Asettings, the Skyview consistently sho wed me cruising at 156KTAS. The=0ASkyview also showed that no matter which direction I was flying, I always=0Ahad a headwind. Knowing that the Skyview did not change the aerodynamics of=0Athe airplane and the system had just passed an IFR check, something was not=0Aright.=0A=0A=0AOn subsequent fligh ts I calculated my TAS using my old CAS chart and came=0Aback to 143KTAS no t the 156KTAS the Skyview was displaying. The plots on my=0ACAS chart shows that as my airspeed increases, IAS and CAS spread apart=0Awith IAS being a lmost 20KT faster at full power. Since the Skyview does not=0Ahave a method of factoring in a CAS, it uses IAS for the calculations. With=0Athe signif icantly higher IAS used by the Skyview it would display a higher=0ATAS than actual matching what I was seeing.=0A=0A=0ATalking with the engineers at D YNON, they told me that in a =93well designe=0Ad=94=0Asystem the differ ence between IAS and CAS should not be more than a few=0Aknots. If my IAS a nd CAS was that far apart, there is a problem with either=0Athe pitot or st atic source position. Having IAS significantly higher than=0ACAS meant that either the pitot tube is in an area of =93higher=94 pressure=0Aor=0Ath e static source is in an area of =93lower=94 pressure. If the pitot is in=0Aan=0Aarea of =93higher=94 pressure the error would only be in airs peed. But if t=0Ahe=0Astatic source is in an area of =93lower=94 pressu re, altitude indications w=0Aill=0Ashow me flying at a higher altitude than I really am. This is a potentially=0Adeadly situation when flying real IMC , which I do.=0A=0A=0ATo isolate if the error was in the pitot or static, I flew to different=0Aairports with ILS approaches over the next few months. I found that when at=0Athe FAF on the glideslope of each airport, the Skyv iew displayed a=0Aconsistent 100-110=92 higher than what the approach pla te showed. In order =0Ato=0Aconfirm what I found, I did several high speed passes, over different=0Aairports, trying to stay about 10=92 above the r unway. At each airport the=0ASkyview displayed a consistent 100-110=92 hi gher than what the runway reall=0Ay=0Awas . This matched what I found with the FAF experiment. Since my CAS chart=0Ashowed the IAS and CAS getting fur ther apart the faster I flew, the data=0Aobtained from the test flights was consistent with the static source being=0Ain an area where pressure drops as airspeed increases. So I needed to=0Acorrect the static source placement .=0A=0A=0AThe dual static source I have was installed by Rich Trickel back in 2008=0Aand I really didn=92t want to change where they were located. S o in order t=0Ao=0Acorrect for a possible changing static pressure situatio n I experimented by=0Aplacing a piece of Gorilla tape just behind each stat ic port hole and doing=0Athe flight checks again. With one piece of tape, t he FAF and high speed=0Arunway checks altitude error dropped to about 40= 92. My displayed TAS error=0A,=0Abased on my CAS chart, had also dropped to about 10kts.=0A=0A=0AI figured I was on the right track so I added a secon d piece of tape=0Aeffectively doubling the thickness behind the static port hole. The next=0Aseries of flights showed my FAF and high speed runway che cks had dropped to=0Awithin a few feet. My TAS error had also dropped to wi thin 2Kts at normal=0Acruise. A third piece of tape caused the FAF and high speed runway checks=0Ato show the altitude difference was about 40=92 bu t in the opposite=0Adirection. Now the TAS error was back to about 10Kts, a lso in the opposite=0Adirection than before. Armed with this information, I went back to using=0Atwo pieces of Gorilla tape just behind the static sou rce hole.=0A=0A=0ADuring the next flights the FAF and high speed runway che cks showed the=0Aaltitude error was within 10 feet of what I was expecting. Additionally I=0Adid a series of maneuvers at different power settings and , by using GPS=0Agroundspeeds, calculated that my TAS was within a few knot s of what the=0ASkyview was displaying. During my final test flight (Octobe r 21, 2013) I=0Afound that normal approach speed (90Kts) and normal cruise (143Kts) speeds=0Awere within 2Kts of calculated. I also found that as I ap proached to land,=0Athe wind aloft display matched very closely to what the tower was=0Areporting. Now I know what I have to do to correct my static s ource=0Aposition error. I can complete the work by making a piece of alumin um the=0Athickness of two pieces of Gorilla tape and permanently attach it just=0Abehind to the static source hole.=0A=0A=0ASo, if your EFIS show an a irspeed higher than what the =93book=94 shows you=0Ar=0Aairplane should be doing, check it out. You may have a pitot/static source=0Aerror that ca n be corrected. Overall I think I corrected a possibly serious=0Asituation and now completely trust my Skyview is displaying correct=0Ainformation.=0A ================= ________________________________ Message 2 _____________________________________ Time: 04:16:38 PM PST US From: SUSAN TRICKEL Subject: KIS-List: Re: KIS-List Digest: 1 Msgs - 10/21/13 =0A =0A=0A________________________________=0A From: KIS-List Digest Server =0ATo: KIS-List Digest List =0ASent: Tuesday, October 22, 2013 3:00 AM=0ASubject: KIS-List Dig est: 1 Msgs - 10/21/13=0A =0A=0A*=0A=0A=========== ===============0A- Online Versions of Today' s List Digest Archive=0A================= =========0A=0AToday's complete KIS-List Digest can also be found in either of the =0Atwo Web Links listed below.- The .html file inc ludes the Digest formatted =0Ain HTML for viewing with a web browser and fe atures Hyperlinked Indexes =0Aand Message Navigation.- The .txt file incl udes the plain ASCII version =0Aof the KIS-List Digest and can be viewed wi th a generic text editor =0Asuch as Notepad or with a web browser. =0A=0AHT ML Version:=0A=0A- - http://www.matronics.com/digest/digestview.php?Sty le=82701&View=html&Chapter 13-10-21&Archive=KIS=0A=0AText Version :=0A=0A- - http://www.matronics.com/digest/digestview.php?Style=82701 &View=txt&Chapter 13-10-21&Archive=KIS=0A=0A=0A====== ==================0A- EMail Version of Today's List Digest Archive=0A============== ==========0A=0A=0A- - - - - ------------------ ----------------------------------------=0A- - - - - - - - - - - - - KIS-List Digest Archive=0A- - - - - - - - - - - - - - - - - - - ---=0A- - - - - - - - - - Total Messages Posted Mon 10/21/13: 1=0A- - - - - ----------------------------------------------------------=0A=0A =0AToday's Message Index:=0A----------------------=0A=0A- - 1. 11:04 P M - TAS Error with my new EFIS- (Galin Hernandez)=0A=0A=0A=0A____________ ____________________- Message 1- _____________________________________ =0A=0A=0ATime: 11:04:20 PM PST US=0AFrom: Galin Hernandez =0ASubject: KIS-List: TAS Error with my new EFIS=0A=0APardon the long wr ite-up.=0A=0AAfter buying my airplane several years ago I did a series of m aneuvers at=0Adifferent power settings and, by using GPS groundspeeds, I ma de a fairly=0Aaccurate calibrated airspeed chart. For the next few years I used the CAS=0Achart often and found that, at normal power settings, I cons istently=0Acruised at 143KTAS.=0A=0A=0AFast forward to this year when I ins talled a complete DYNON Skyview EFIS=0Asystem which automatically calculate s TAS. But, at normal cruise power=0Asettings, the Skyview consistently sho wed me cruising at 156KTAS. The=0ASkyview also showed that no matter which direction I was flying, I always=0Ahad a headwind. Knowing that the Skyview did not change the aerodynamics of=0Athe airplane and the system had just passed an IFR check, something was not=0Aright.=0A=0A=0AOn subsequent fligh ts I calculated my TAS using my old CAS chart and came=0Aback to 143KTAS no t the 156KTAS the Skyview was displaying. The plots on my=0ACAS chart shows that as my airspeed increases, IAS and CAS spread apart=0Awith IAS being a lmost 20KT faster at full power. Since the Skyview does not=0Ahave a method of factoring in a CAS, it uses IAS for the calculations. With=0Athe signif icantly higher IAS used by the Skyview it would display a higher=0ATAS than actual matching what I was seeing.=0A=0A=0ATalking with the engineers at D YNON, they told me that in a =93well designe=0Ad=94=0Asystem the differ ence between IAS and CAS should not be more than a few=0Aknots. If my IAS a nd CAS was that far apart, there is a problem with either=0Athe pitot or st atic source position. Having IAS significantly higher than=0ACAS meant that either the pitot tube is in an area of =93higher=94 pressure=0Aor=0Ath e static source is in an area of =93lower=94 pressure. If the pitot is in=0Aan=0Aarea of =93higher=94 pressure the error would only be in airs peed. But if t=0Ahe=0Astatic source is in an area of =93lower=94 pressu re, altitude indications w=0Aill=0Ashow me flying at a higher altitude than I really am. This is a potentially=0Adeadly situation when flying real IMC , which I do.=0A=0A=0ATo isolate if the error was in the pitot or static, I flew to different=0Aairports with ILS approaches over the next few months. I found that when at=0Athe FAF on the glideslope of each airport, the Skyv iew displayed a=0Aconsistent 100-110=92 higher than what the approach pla te showed. In order =0Ato=0Aconfirm what I found, I did several high speed passes, over different=0Aairports, trying to stay about 10=92 above the r unway. At each airport the=0ASkyview displayed a consistent 100-110=92 hi gher than what the runway reall=0Ay=0Awas . This matched what I found with the FAF experiment. Since my CAS chart=0Ashowed the IAS and CAS getting fur ther apart the faster I flew, the data=0Aobtained from the test flights was consistent with the static source being=0Ain an area where pressure drops as airspeed increases. So I needed to=0Acorrect the static source placement .=0A=0A=0AThe dual static source I have was installed by Rich Trickel back in 2008=0Aand I really didn=92t want to change where they were located. S o in order t=0Ao=0Acorrect for a possible changing static pressure situatio n I experimented by=0Aplacing a piece of Gorilla tape just behind each stat ic port hole and doing=0Athe flight checks again. With one piece of tape, t he FAF and high speed=0Arunway checks altitude error dropped to about 40= 92. My displayed TAS error=0A,=0Abased on my CAS chart, had also dropped to about 10kts.=0A=0A=0AI figured I was on the right track so I added a secon d piece of tape=0Aeffectively doubling the thickness behind the static port hole. The next=0Aseries of flights showed my FAF and high speed runway che cks had dropped to=0Awithin a few feet. My TAS error had also dropped to wi thin 2Kts at normal=0Acruise. A third piece of tape caused the FAF and high speed runway checks=0Ato show the altitude difference was about 40=92 bu t in the opposite=0Adirection. Now the TAS error was back to about 10Kts, a lso in the opposite=0Adirection than before. Armed with this information, I went back to using=0Atwo pieces of Gorilla tape just behind the static sou rce hole.=0A=0A=0ADuring the next flights the FAF and high speed runway che cks showed the=0Aaltitude error was within 10 feet of what I was expecting. Additionally I=0Adid a series of maneuvers at different power settings and , by using GPS=0Agroundspeeds, calculated that my TAS was within a few knot s of what the=0ASkyview was displaying. During my final test flight (Octobe r 21, 2013) I=0Afound that normal approach speed (90Kts) and normal cruise (143Kts) speeds=0Awere within 2Kts of calculated. I also found that as I ap proached to land,=0Athe wind aloft display matched very closely to what the tower was=0Areporting. Now I know what I have to do to correct my static s ource=0Aposition error. I can complete the work by making a piece of alumin um the=0Athickness of two pieces of Gorilla tape and permanently attach it just=0Abehind to the static source hole.=0A=0A=0ASo, if your EFIS show an a irspeed higher than what the =93book=94 shows you=0Ar=0Aairplane should be doing, check it out. You may have a pitot/static source=0Aerror that ca n be corrected. Overall I think I corrected a possibly serious=0Asituation and now completely trust my Skyview is displaying correct=0Ainformation.=0A ================= ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message kis-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/KIS-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/kis-list Browse Digests http://www.matronics.com/digest/kis-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.