RE: Europa-List: Re: What did you do with your Europa this week - 08/11/22

[Bud Yerly <budyerly@msn.com>]

It always makes sense to do that.  In the max range computations from Aero 
it looks like this:

Shown in green is a tailwind, red is no wind, and pink is a headwind.  For 
a small plane it isn=92t much of a speed difference but max range is rarely
 flown either in a light plane.

No experimental manufacturer makes charts for best range, cruise, headwind,
 tailwind or altitude.  You have to do that yourself.


[Chart, line chart  Description automatically generated]


Look at the charts from the manufacturer.  You can see the HP vs FF at diff
erent power settings.  If you pull the power back to say 4800/28 inches slo
ws the plane fuel burn and gets you closer to your max range.  Then at vari
ous altitudes and power setting within the limits in the charts.

                Alt          RPM      MP         FF           IAS         T
AS        ANMPG

                10000    5500       35           6.9          122         1
45         21.0

                                5200       32           6              120 
        140         23.3

                                5000       31           5.6          116   
      138         24.6

                                4800       28           4.6          106   
      128         27.8

As you can see, less speed, less drag (until L/D max) which means power is 
less as is fuel flow and range increases until that tangent point above.  E
ven with this prop (it was not an impressive prop) it clearly shows it take
s about 50 HP to do 48/28, but to go down to 4500/28 the engine sounds like
 it is lugging but fuel flow is now 4 GPH and the speed is down to about 11
0 KTAS and the ANMPG starts to go up.  Now you know you have about your pro
per power setting for max range.  You also have to think about the engine. 
 Lugging down the engine is not good, neither is running the oil and cht te
mps too low in the quest for max range.  The unfortunate thing in most engi
nes is we can=92t control our boost, we only control the throttle plate and
 the TCU controls the wastegate.  The Bing controls the fuel flow  and even
tually you hit operational limits.  The 912iS and 915 attempted to make the
 engine more efficient and it gets the fuel flow and power lower than a nor
mal 914 but you must use care with the RPM or prop control.  Pull the RPM d
own too low and you can still lug the engine and perhaps even detonate it a
s the =93I=94 engines don=92t have an antiknock sensor.


You=92ve got to know your limitations I guess.


Regards,

Bud Yerly


-----Original Message-----
From: owner-europa-list-server@matronics.com <owner-europa-list-server@matr
onics.com> On Behalf Of lantieau
Sent: Thursday, November 10, 2022 4:55 PM
Subject: Europa-List: Re: What did you do with your Europa this week - 08/1
1/22


ropa@antieau.org>>


These are great insights, thanks for providing details.  It does seem there
 are significant advantages to the 914 vs a 912S.  The focus always seems t
o be on maximizing speed at the cost of range.


If you're flying at high altitude with a 914 with a decent tailwind, does i
t make sense to pull the power to a low cruise setting to save fuel while k
eeping a reasonable speed?  You mention that we should expect 25 ANMPG with
 a 914.  What does that number look like at a reduced power setting at alti
tude?


My thinking is that a low power cruise would allow to sacrifice some speed 
in exchange for more time aloft, in the end, increasing range and ANMPG.  W
ith a 914, what is the optimal power setting/altitude to mazimize fuel econ
omy/range assuming wind is not a factor?


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