Murphy Rebel with Rotax 912
Posted: Fri Feb 17, 2012 5:26 pm
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To: Ian Donaldson <allsure@ne.com.au>,murphy-rebel@dcsol.com
From: Bob Patterson <bob.patterson@canrem.com>
Subject: Re: Murphy Rebel with Rotax 912
Message-Id: <E11Gw2x-0003zI-00@mail4.toronto.istar.net>
Date: Tue, 17 Aug 1999 23:05:51 -0400
Hi !
Don't really need a kitchen sink, but I know of one Rebel that has
a porta-potty installed in the back !! :-)
Canada has been 'going' metric for about 30 years, but VERRRRY slowly !
I was raised on the old stuff, and have a devil of a time with the new kids.
(I'm a glider instructor on weekends, sometimes ....) Things like "Start
to break your glide about 50 feet up, and level off at about 3 feet "
get me blank looks & puzzled expressions !!! :-) Our schools have taught
metric for a long time, and temperatures & highway speed limits are all
metric, but aviation is a peculiar backwater of its own, with KNOTS &
other weirdnesses ....
I used to enjoy trips to the USA, because they used REAL temperatures -
but I had a hard time when we got back, this year..... People looked
blank when I said it was 115 degrees on Friday - had to scribble for a while
to translate to 46 degrees Centipeed - then folks said "Wow, that WAS hot !"
Must say, I still like airspeed in miles per hour - knots gives too low
a number :-(, and kilometers gives such a large number nobody believes it !!
And I'm used to altitude in feet ... We have received a few European
gliders
with metric instruments, but the altimeters in meters were too coarse to be
much use (I suppose they make 'em with 2 needles now ...).
The 3 gallons/hour fuel burn for the 912 is Imperial gallons - about
4.5 litres. This is odd, since our fuel pumps have been metric for MANY
years - but I've re-calibrated the fuel guages .... one day I MUST go
metric ....
Shell Gold is unleaded, about 94 octane. Leaded gas is unavailable for
cars. 100 Low-Lead is the most common aviation fuel, and very few airports
sell 'mogas'. Auto fuel (regular), runs about $0.55/liter, and premium is
about $0.70/liter (Canadian pesos :-( ) Avgas is about $0.90/liter....
probably less expensive than down under, but MUCH more than the Americans
pay - they're still about $1.00 - $1.35 USD/US gallon, and $2.10 for avgas
!!
The 912 will run happily on 100 LL, and we have to use it on long
trips,
because getting car gas is too awkward at most places. It does get harder
to start after about 50 hours or so of steady 100LL - plug fouling. After
more time, there is a power loss, due to lead buildup on the valves -
running auto fuel for 20 Hr. or so cleans this off. I have also put a bit
of Avblend (snake oil !) in the gas for a couple of tankfuls, to help with
this problem.
I was cruising at 102 - 104 mph a few weeks ago - just tweaking the
prop... really slowed the takeoff & climb, though ! We have a 2 bladed
GSC ground-adjustable wood prop, with epoxy leading edges - this is included
in the F/W-forward package, I believe. It is VERY difficult to get both
blades set to the same pitch - I believe we are about 13 degrees at the
moment, but the absolute setting isn't really that important, just the
relative angle, and that both are the same.... The protractor they (GSC)
supply is almost useless - and the Warp Drive one is only slightly better !
I made my own, and used it for years, but the last set of new prop blades
had more of a curve on the back, and there isn't a flat spot to measure
the angle on. Have now resorted to an electronic digital level - no more
trying to center a bubble or a string, just a large number, to 1/10th of
a degree !! Now if I could just figure out WHERE to measure .... :-)
You will likely get about 95 mph to start with - the 912 takes a LONG
time to break in. We were able to increase the pitch every 200 hours, up
to 600 hours, to keep it under redline on climb !
We cruise at 5,400 rpm, as 5,500 is max. continuous, with 5,800 allowed
for a max. of 3 minutes (used for climb after takeoff, as it takes a lot
less to get to 1,000 ft. (circuit altitude)...). Solo climb is about 1,100
fpm....
The biggest single factor in good cruise is streamlined fairings -
cleaning up the landing gear gave 10 mph !! Streamlined covers on the main
gear legs, right up to the fuselage, and both inside legs, over the bungees,
and the top tubes, made the difference. Being glider pilots, we also used
tapes on the strut fairings, and wing roots ....
Probably the biggest service you could render other builders would be
to ask these questions on the mail list - that's what it's for, and then
everyone can benefit from the answers (and I won't have to do it again
for the next 912 builder .... :-) THANKS !!!
Please feel free to ask any and all questions - we all need help at
some point, even if it's just (im)moral support !! :-) I'm completely
convinced that help from other builders is the reason there are now so
many more 'high-serial-number' Rebels flying, giving encouragement and
motivation to those still rivetting ....
.....bobp
Hope you don't mind - I've forwarded this to the 'list' .....
----------------------------orig.--------------------------------------
At 09:47 PM 8/16/99 +1000, you wrote:
(helo=ip139.mississauga.dialup.canada.psi.net)
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id 11Gw2x-0003zI-00; Tue, 17 Aug 1999 23:05:51 -0400
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To: Ian Donaldson <allsure@ne.com.au>,murphy-rebel@dcsol.com
From: Bob Patterson <bob.patterson@canrem.com>
Subject: Re: Murphy Rebel with Rotax 912
Message-Id: <E11Gw2x-0003zI-00@mail4.toronto.istar.net>
Date: Tue, 17 Aug 1999 23:05:51 -0400
Hi !
Don't really need a kitchen sink, but I know of one Rebel that has
a porta-potty installed in the back !! :-)
Canada has been 'going' metric for about 30 years, but VERRRRY slowly !
I was raised on the old stuff, and have a devil of a time with the new kids.
(I'm a glider instructor on weekends, sometimes ....) Things like "Start
to break your glide about 50 feet up, and level off at about 3 feet "
get me blank looks & puzzled expressions !!! :-) Our schools have taught
metric for a long time, and temperatures & highway speed limits are all
metric, but aviation is a peculiar backwater of its own, with KNOTS &
other weirdnesses ....
I used to enjoy trips to the USA, because they used REAL temperatures -
but I had a hard time when we got back, this year..... People looked
blank when I said it was 115 degrees on Friday - had to scribble for a while
to translate to 46 degrees Centipeed - then folks said "Wow, that WAS hot !"
Must say, I still like airspeed in miles per hour - knots gives too low
a number :-(, and kilometers gives such a large number nobody believes it !!
And I'm used to altitude in feet ... We have received a few European
gliders
with metric instruments, but the altimeters in meters were too coarse to be
much use (I suppose they make 'em with 2 needles now ...).
The 3 gallons/hour fuel burn for the 912 is Imperial gallons - about
4.5 litres. This is odd, since our fuel pumps have been metric for MANY
years - but I've re-calibrated the fuel guages .... one day I MUST go
metric ....
Shell Gold is unleaded, about 94 octane. Leaded gas is unavailable for
cars. 100 Low-Lead is the most common aviation fuel, and very few airports
sell 'mogas'. Auto fuel (regular), runs about $0.55/liter, and premium is
about $0.70/liter (Canadian pesos :-( ) Avgas is about $0.90/liter....
probably less expensive than down under, but MUCH more than the Americans
pay - they're still about $1.00 - $1.35 USD/US gallon, and $2.10 for avgas
!!
The 912 will run happily on 100 LL, and we have to use it on long
trips,
because getting car gas is too awkward at most places. It does get harder
to start after about 50 hours or so of steady 100LL - plug fouling. After
more time, there is a power loss, due to lead buildup on the valves -
running auto fuel for 20 Hr. or so cleans this off. I have also put a bit
of Avblend (snake oil !) in the gas for a couple of tankfuls, to help with
this problem.
I was cruising at 102 - 104 mph a few weeks ago - just tweaking the
prop... really slowed the takeoff & climb, though ! We have a 2 bladed
GSC ground-adjustable wood prop, with epoxy leading edges - this is included
in the F/W-forward package, I believe. It is VERY difficult to get both
blades set to the same pitch - I believe we are about 13 degrees at the
moment, but the absolute setting isn't really that important, just the
relative angle, and that both are the same.... The protractor they (GSC)
supply is almost useless - and the Warp Drive one is only slightly better !
I made my own, and used it for years, but the last set of new prop blades
had more of a curve on the back, and there isn't a flat spot to measure
the angle on. Have now resorted to an electronic digital level - no more
trying to center a bubble or a string, just a large number, to 1/10th of
a degree !! Now if I could just figure out WHERE to measure .... :-)
You will likely get about 95 mph to start with - the 912 takes a LONG
time to break in. We were able to increase the pitch every 200 hours, up
to 600 hours, to keep it under redline on climb !
We cruise at 5,400 rpm, as 5,500 is max. continuous, with 5,800 allowed
for a max. of 3 minutes (used for climb after takeoff, as it takes a lot
less to get to 1,000 ft. (circuit altitude)...). Solo climb is about 1,100
fpm....
The biggest single factor in good cruise is streamlined fairings -
cleaning up the landing gear gave 10 mph !! Streamlined covers on the main
gear legs, right up to the fuselage, and both inside legs, over the bungees,
and the top tubes, made the difference. Being glider pilots, we also used
tapes on the strut fairings, and wing roots ....
Probably the biggest service you could render other builders would be
to ask these questions on the mail list - that's what it's for, and then
everyone can benefit from the answers (and I won't have to do it again
for the next 912 builder .... :-) THANKS !!!
Please feel free to ask any and all questions - we all need help at
some point, even if it's just (im)moral support !! :-) I'm completely
convinced that help from other builders is the reason there are now so
many more 'high-serial-number' Rebels flying, giving encouragement and
motivation to those still rivetting ....
.....bobp
Hope you don't mind - I've forwarded this to the 'list' .....
----------------------------orig.--------------------------------------
At 09:47 PM 8/16/99 +1000, you wrote:
G'day Bob
Thanks for your very detailed and informative response. I found it quite
helpful.
Its a pity that the Rebel has such poor carrying capacity. It's a shame
that you can't fit in the kitchen sink :-)
It is comforting to learn that you have had such a good run from the
Rotax and are happy with the performance. I have never really considered
using an "aircraft" engine as they are so prohibitively expensive over
here, but did think of an auto conversion. As I have ordered the Rotax
firewall forward kit I guess that I will go for the Rotax option and
probably the 100hp version, and yes I have ordered the standard Rebel.
Something that is causing me some consternation, is that all the Murphy
kit measurements are Imperial.. Here in Australia we have been
metricated for over thirty years, and now I am struggling a bit with
having to come to a re-understanding of the Imperial system even though
I grew up with the "old"measure. I have had to scrounge around to find
tapes and rulers that show both scales. I notice that your performance
data is in a mixture of old and new, so I guess you will sooner or later
move to the metric system.
I have a few questions that have arisen from your letter and I would
appreciate some further information.
Your cruise speed is impressive! What revs is your engine turning and
what propellor and pitch have you found to be the best?
What octane is Shell premium? Is it leaded or unleaded?
Are your gallons measured in US gallons?
I guess as time goes on I will have lots of other questions and would
appreciate some assistance if it is no bother.
Thanks and regards
Ian Donaldson