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1. 12:58 PM - RV-8A Numbers (Speedy11@aol.com)
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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)
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