 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
lcfitt(at)sbcglobal.net
Guest
|
 Posted: Sun Jul 02, 2006 9:50 am Post subject: Rotax vs. Jabiru |
 |
|
Michel,
During the Rotax vs. NSI EA-81 weight dicussions, Murle Williams weighed
both and the Rotax 912 UL came in at 169 lbs with fluids, so I am told by
one of the Desert Fox guys. He put everything on a platform scale and
weighed the whole thing in one shot. Accordint to Jabiru USA, the 2200
weighs 132 lbs. This appears to save about 30 lbs, but one weight is from a
builder assist shop and the other is from the vendor (?), The 3300, which
is the engine in the discussion is reported to weigh 178 lbs for a weight
penalty of 11 lbs for the additional 20 hp and the Rotax 912 ULS weight is a
bit higher - well under 10 lbs I believe. This is not bad if all that power
can be transferred through the
prop.
Last week during the first leg of the Utah flight, I flew 3.5 hours and
burned 14.2 US gallons and the line boy topped up the fuel tanks higher than
I did on departure so actual fuel burn was a tad less than that. Using that
number and the
handy on line volume conversion and a calculator, I find that I burned 4.057
gallons per hour and the equivalent of 15.4 liters per hour - somewhat more
than your 12 liters per hour, but keep in mind this included an initial
climb to 10,500 feet to clear the Sierras - 9,300 foot (net) - and a cruise
of about 105 mph. As the crow flies the distance was 314 miles and in
actuality was probably closer to 325 miles or so given that we fly the
highways when traversing the mountains and diverted a bit to Derby (LOL)
because we thought three other airplanes - Rans, in fact - were expected to
catch up to us there - they didn't so we pressed on.
It is interesting that in the article you referenced - good read,
incidentally - the cruise RPMs given for the Rotax (4750) is well below the
Rotax allowable cruise of (5500). In fact Rotax recommends that cruise be
kept above 5000 rpm due to gear box issues. My cruise was about 5000
during my trip. My only fault in the article is that data like that can be
confusing. For example, there is a beautiful Grass Strip in Idaho called
Johnson Creek. It is over 3000 ft long and 150 ft wide. All arrivals are
made to the south to avoid over flying the donors private residence and all
departures are made to the North for essentially the same reason. There is
a ridge that extends partially into the valley floor to the East beyind the
departure end of the runway with a fork in the river turning Eastward behind
it. The main river turning gently Westward beyind the fork and beneath a
high ridge we call the notch. A typical deperture is to lift off and
immediately turn toward the right side of the canyon to catch any ridge lift
there. The airplane seems to disappear behind the Eastern ridge as it
follows the contour and reappears as it flies against the slope under the
"notch" only to disappear again behind the ridge to the West as it follows
the main river to gain altitude. The typical certified airplane departing
will be about 1/3 the height of the "notch" as it passes Westward below it.
One of our testesterone tests is to see who can climb straight through the
"notch" We fly in loose formation so the conditions are all identical, as
are likely the flying weights (Max Gross) as we all have our camping gear
including camp chair, full fuel etc. I think this type of test could settle
most questions, but not all, of course. It includes not only the climb
performance of the airframe, engine and prop, but addresses cooling issues
as well. On the upward slide of the Sierras last week some of the Rans
lagged behind due to cooling issues. That was not engine related, but
rather installation related as we were all running Rotax. If the airframe
was all Kitfox, the same issues might surface, but it could then be more
easily thought of as an engine issue as engine / prop mated to airframe is
the real issue as far as performance is concerned.
Then, of course would be the long straight flights at all sorts of altitudes
in cruise and then the inevitable fuel stop and all the eyes on the fuel
quantity gauge. We are, in fact, a competitive, though congeniel group.
What does all this mean? Who knows. That is why I would look forward to a
Jabiru powered airplane to accompany us to the back country to evaluate the
performance in all perameters - cooling, fuel burn, climb, cruise etc.
After the four or five trips there with the airplanes, engines and props, I
think there are some conclusions that can be made. we just need more
variety in engines. We have had a 582 on three of the trips, GSC, Warp as
well as NSI CAP and PowerFin props, clean airplanes, and cleaned up
airplanes. The rest of the engines have been 912 ULs and 912 ULSs, Kitfox
IVs and Vs nothing newer than that and of course the Rans S6S and Rans S7.
And of course the pilots - big differences can be seen there too. Some can
just get more out of an airplane than others can.
Personally, I would go again with the Rotax, but that is what I know and for
me it has been near bulletproof. No cooling issues, never a thrown
carburetor, no cracks anywhere, but to be strictly honest I suffered four
stuck valves in Afton Wyoming two years ago on the way to Oshkosh - likely
from the lead in the Avgas. This was solved by running a couple of quarts
of ATF through the engine there - we couldn't find Marvel Mystery oil. I
carry it faithfully now, but haven't used any, except in my lawnmower.
Incidentally, I just went through 790 hours on the way home last week.
Lowell
---
| | - The Matronics Kitfox-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kitfox-List |
|
|
|
| Back to top |
|
 |
Michel
Joined: 10 Jan 2006
Posts: 966
Location: Norway
|
| Posted: Sun Jul 02, 2006 10:21 am Post subject: Rotax vs. Jabiru |
|
|
On Jul 2, 2006, at 7:48 PM, Lowell Fitt wrote:
| Quote: | Personally, I would go again with the Rotax, but that is what I know
and for me it has been near bulletproof.
|
I am sure it is, Lowell. As I wrote earlier, both are fine engines,
and, as you wrote yourself, we need different engines to choose from.
The more the better.
Cheers,
Michel
do not archive
| | - The Matronics Kitfox-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kitfox-List |
|
_________________
Kitfox 3 - Jabiru 2200 |
|
| Back to top |
|
|
darinh
Joined: 20 Apr 2006
Posts: 327
Location: Utah
|
| Posted: Sun Jul 02, 2006 11:39 am Post subject: Re: Rotax vs. Jabiru |
|
|
Lowell,
I may very well be that "other" Kitfox to fly into Idaho with you in year or so if I go with the Jabiru. I am located out of Ogden, Utah and get into Idaho a number of times a year. It would be great to be able to compare a number of different engines on essentially the same airframe. However, I don't want to regret my engine choice as it is a very significant amount of money so I will keep doing my homework and hopefully make the best decision for me and my type of flying. Once the choice is made it is a bit difficult to swap as you know.
Thanks for the input,
Darin
| | - The Matronics Kitfox-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kitfox-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
