---------------------------------------------------------- RV8-List Digest Archive --- Total Messages Posted Tue 09/28/10: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:58 PM - RV-8A Numbers (Speedy11@aol.com) ________________________________ Message 1 _____________________________________ Time: 12:58:02 PM PST US From: Speedy11@aol.com Subject: RV8-List: RV-8A Numbers Without an aero engineer degree, it=99s often difficult to know if the numbers you are getting with your RV are accurate. I have done multiple TAS calculations using GPS triangles and feel confident in my TAS indications. But, I am a fan of IAS =93 despite it=99s well known variatio ns. IAS is something I can see and easily reference in the cockpit and it is indicati ng how many air molecules are passing the airplane. So long as the pitot-static is properly functioning, I have solid confidence in the IAS. If I lose that confidence, I can drop back and reference other speed or power indication s. I have neither the knowledge nor the desire to determine my exact CAS at various speeds, so one way to check my numbers is to compare them with a like airplane. I flew formation with another RV-8A with the same engine to compare numbers because his IAS was dramatically better than mine. Turns out his IAS was not even close to accurate. That doesn=99t really matte r so long as he knows the numbers for his particular aircraft. But, when comparing aircraft using textual information, the comparison is more difficult. I have wondered how the numbers I=99m getting compare to other RVs ac ross the country. So, for anyone who is wondering about their RV-8A compared to others, I=99m posting some numbers that I recently recorded. The Fuel Flow numbers are estimates since my FF readings are not yet accurate. Altitude MP RPM KIAS KTAS FF (approx) EGT 1000 26 2500 178 182 15.0 Peak 2500 25.2 2500 165 172 12.5 ROP 4500 26 2400 169 184 13.5 40ROP 10500 20.8 2000 na na 9.0 Peak 11500 20.1 2300 142 172 10.5 Peak 11500 20.0 2240 137 166 10.1 Peak 17500 15.4 2400 124 166 7.8 Peak 17500 15.4 2300 120 162 7.8 Peak 20000 13.8 2400 113 160 7.0 Peak 24000 11.5 2500 89 135 7.2 70LOP 24000 11.5 2300 92 139 6.9 40LOP 24000 11.6 2200 88 134 7.0 60ROP My deduction is that my engine is using far more fuel than other similar engines. I don=99t know why, but that seems to be that case. The accuracy of all numbers above have been verified by using other measuring means. The only one that is still inaccurate is the FF. I=99ve been making adjustments to the FF values in the engine monitor, but can=99t get it narrowed to accuracy. Based on my numbers thus far, I will plan the following for cross country : High Altitude to gain a tailwind FL200 2300RPM 7.0 FF 160 KTAS Medium Altitude 11500 2200RPM 9.0 FF 160 KTAS 8500 2200RPM 9.2 FF 160 KTAS Low Altitude 2500 2300RPM 9.5 FF 160 KTAS What numbers are you using? Stan Sutterfield _www.rv-8a.net_ (http://www.rv-8a.net) ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rv8-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RV8-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/rv8-list Browse Digests http://www.matronics.com/digest/rv8-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.