My two sense (since I really don't want to work on what I should be) if
you have a 914 you climb better so we normally use that to our
advantage. A short wing at 1370 lbs from TO takes 15-20 minutes to
level off at 12,000. Fuel used 2.5 gallons start, taxi, TO to L/O.
A similarly equipped 912S will take 25-30 minutes and 3.5 gallons. Both
climbing at 90 KIAS ish.
Once level, figure your true airspeed (nominally about 10 Kts between
the two engines) and the difference in climb distance to cruise and I
have found the optimum altitude for best range to be nominally 8500-9500
for a 2.5 hour trip. No oxygen required either engine.
But then again, I have a 2.5 hour bladder any more, plus I get bored.
The plane just flies too well. In the 914 I go 270-300 miles, and in a
similar 912S I go 250-270 and on landing, put 10 gallons in the tank and
drain my bladder.
In Florida, the tops of the bumpers on a nice day are about 8500, and it
is nice to cruise climb a bit higher to 10.5. Pull the throttle back to
68% and 4.6 GPH once level then plan a long slow descent, your fuel
usage is quite low and you can do the 2.5 hour trip at or near 35MPG
truing about 127 ish. If I pick up the speed my milage drops to
25-30MPG (even in a trigear) truing a bit faster and climbing higher is
done for comfort only, not economy. Each plane and engine prop
combination has to be tested for optimum cruise performance. Some of
our birds are draggy and built for fun, and others are stripped down
speed merchants with extended range tanks and pilots with tight urinary
tract control.
The new 912iS appears to be the ticket. I'll wait a bit for them to
figure out maintenance, injector cleaning, etc. Then the extra fuel
savings of the iS may be able to put more legs on the trip and frankly
better efficiency for the normally aspirated engine.
I refuse to get into a contest on which engine is better. Your flying
desires, density altitude operation, personal stomach for maintenance
costs, and type of aircraft all affect a subjective decision. I hate my
914 (except when it behaves), and I hate the 912S (when shaking on start
and stop). I love and hate both these engines and the new engines (UL,
MW, Jabiru) so I do not descriminate, I hate them all, except when I
love them.
Bud
----- Original Message -----
From: h&jeuropa<mailto:butcher43@att.net>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Friday, April 26, 2013 7:06 AM
Subject: Europa-List: Re: flying at what altitude
<butcher43@att.net<mailto:butcher43@att.net>>
Graeme,
We agree with all the above and add that altitude gives you more
landing options in case of a problem - more potential landing sites and
more time to figure out your course of action.
Jim & Heather
N241BW
XS Mono 914
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