Lynn Matteson
Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan
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 Posted: Thu Jan 28, 2010 12:51 pm Post subject: Jabiru 2200 and Rotec TBI @ 10,000 feet |
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About a month ago, I was asked how I felt the Rotec TBI would work on
my plane if I were to land and take off at 10,000 feet. A friend of
the requester was having troubles with his new Jabiru 2200 in an
Avid, and had tried a Hacman without much success. I told him I'd go
up to 10,000 feet and try some "pretend landings". Well, yesterday I
got the chance to go up there to make practice landings in my plane.
I didn't record a whole lot of data about the flight, but I did note
7 degrees F at 10,000 feet, and 2.7 gph at 2700 rpm, going 29 mph
into the wind groundspeed with 72 mph showing as airspeed. Turning
the other way showed 154 mph ground and 70 mph airspeed, same 2.7 gph
fuel usage. So I was seeing a little bit of wind. : )
The operation of the Rotec TBI was nothing out of the ordinary at
that altitude, or at 12,000 feet when I tried the same landing
practice. I reduced the airspeed (slightly across the wind) to about
40 mph, reducing throttle, pulling the mixture back to lean (like I
always do when landing) and dropped the flaperons all the way, got
the speed down to about 30 mph maybe, then at just about "touchdown",
I went for a go-around. I went full rich, full throttle, and got rid
of flaps. I had to pull back a bit on the throttle just like I have
to when taking off from land....the TBI-40 is *just* a bit tiny bit
too much air for the 2200 in my particular installation, (in
agreement with the folks at Rotec.) With the throttle pulled back a
bit, I was climbing out at 400 fpm initially, then it dropped a bit
to about 300 fpm. What I forgot about was possibly leaning out the
mixture a bit to compensate for the high altitude. It certainly
needed to be done to cruise at those altitudes, so I think that
perhaps that even at full power, a bit of leaning might have helped.
Another bit of trivia....I was using a cut-down 62" x 46" Sensenich
prop, cut to 55.5" x 46". I have found over the past 4 winters that
my rpm drops to about 2710-2740 during cold weather (Bing or TBI...no
difference), and that caused some puckering during takeoffs (now
where the hell did that seat cushion go?), so I took my old wood prop
which had some cracks developing on the tips, and cut it down about
1-1/2" on each end. That didn't make much difference, so I lopped off
another inch or so, and one end was a bit ragged after that cut, so I
built a jig to trim it, and the final result was 55 -1/2 inches. Now
I can climb out turning about 2950-2980, and I've found the seat
cushion and a few other things that I had missed right after winter
takeoffs. : )
The updraft intake manifold seems to love this short prop, as for
some reason it runs best while turning more rpm than I was used to
using. I'll go back to my longer prop when the weather warms, but for
now I'm using the "stub."
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062, 841.8 hrs
Countdown to 1000 hrs~158 to go
Sensenich 62"x46" Wood (summer)
Sensenich 55.5" x 46" Wood (winter)
Electroair direct-fire ignition system
Rotec TBI-40 injection
Status: flying (and learning)
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_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM |
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