Today's Message Index:
----------------------
1. 04:14 AM - Re: Re: setting prop pitch (Dave Austin)
2. 05:32 AM - gear box insp. ()
3. 05:51 AM - Setting prop pitch (R Holder)
4. 06:06 AM - Re: Changing Coolant (michael baker)
5. 08:28 AM - Re: Setting prop pitch (Duncan & Ami McFadyean)
6. 08:38 AM - Re: Changing Coolant (darinh)
7. 08:42 AM - Re: Rotax Oil Filter (darinh)
8. 09:06 AM - Re: gear box insp. (rampil)
9. 09:25 AM - Re: Re: gear box insp. (John Cox)
10. 03:07 PM - Re: setting prop pitch (Roger Lee)
11. 03:21 PM - Re: gear box insp. (Roger Lee)
12. 03:23 PM - Re: Free Wheeling Prop (pperrynas)
13. 05:49 PM - Re: Re: setting prop pitch (Dave Austin)
14. 06:06 PM - Re: Free Wheeling Prop (Dale Orth)
15. 07:02 PM - Re: gear box insp. (Paul McAllister)
16. 09:44 PM - Re: setting prop pitch (Roger Lee)
Message 1
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| Subject: | Re: setting prop pitch |
Chris Heitz used to recommend cruise at 5500 but I've always used 5300/5400
as that was where the engine runs the smoothest. If you set it up as cruise
at 5500, how do you go any faster without over-revving the engine?
Dave Austin 601HDS - 912
Message 2
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Good morning guys,
Does anyone know the requirements for the 912 gear box inspection at 600
hrs. ? Someone told us it requires going to a Rotax repair center and costs
around 6 or $ 800 ?, and that an A&P can't do it ?
Bob Griffin
Message 3
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| Subject: | Setting prop pitch |
> Set the prop to 5500 WOT flat and level, but that is
> not where you cruise. When the prop is set to 5500 you
> benefit from the prop pitch during other times such as
> in takeoff with better climb performance, lower
> throttle setting for cruise means a little better fuel
> economy. If it is set for 5500 and lets say you bounce
> up off the runway and you go "oh no I'm going to drop
> it in", then when you give it full throttle trying to
> save yourself the engine will spin up faster to save
> you, compared to, if you had too big a bite of air with
> the prop and it had to struggle to spin up. If the prop
> is pitched too much you will need to give it more
> throttle/fuel to achieve your cruise speed. When it is
> set for 5500 you will be able to pull back on the
> throttle/less fuel and still cruise at the speed you
> want. You will have a higher top end speed, too. Mind
> you we are comparing 5500 to your 4800 here. A 700 rpm
> gain will make a big difference. I know some that
> cruise at 5500 WOT just to cruise. This will cause
> extra wear over time. My question is why? Do you need
> to get somewhere a few miles per hour faster all the
> time? Why wear and tear any extra on the engine than
> need be. We want it to be reliable for its 1500 hours
> and more.
I think you need to stress (I think this is right) that
the 5500 WOT is static, on the ground. The rpm for WOT in
the cruise will depend on a number of factors.
But i would like to ask if anyone has a 912S/ULS with an
airmaster prop and a MAP guage _AND_ a fuel flow meter.
Could they do an experiment for me ! Chose a specific
airspeed (X) at around your normal cruise speed. I would
use 115 knots on my plane.
Now there are a number of combinations of rpm and MAP that
will achieve that airspeed. I use 25 inches and 4600.
The experiment is to set different rpms; and for each
adjust the MAP so that the airspeed is X (stabilised).
Then for each combination of rpm/MAP record the fuel flow
- ideally to the tenth of a litre but a tenth of a US
gallon would be OK.
As the engine must be producing the same horsepower as it
is travelling at the same speed for each combination, any
variation in the fuel flow is a measure of the efficiency
of the engine. If the efficiency is the same for the whole
rpm range tested then the fuel flow would be the same. So
a "scientific" test will show any variation and maybe
there will be an obvious peak to the efficiency - this
will be where the fuel flow is least.
According to Roger's recent postings the implication is
that this peak efficiency rpm/MAP combination will be at
or around 5000 rpm.
If several people are able to do this, please post results
direct to me so that I can collate independently :-) The
critical factor here is that the MAP must be adjusted to
get the same airspeed (X) for each rpm figure tested.
So the results might look like the following
at 115 knots
4500 26 15.8 (15.8 would be the litres per hour fuel
flow)
4600 25 15.5
4700 24.5 15.5
4800 24 15.3
4900 23.5 15.1
5000 23.1 15.0 <------ B E S T E F F I C I E
N C Y
5100 22.8 15.2 O N T H E S E T E S T F I
G U R E S
5200 22.4 15.4
5300 22.1 15.5
It would be something to pass the time on your next two
hour flight !
And if you had longer, other speeds could also be tried -
X+10 and X -10 !
I will ask the wear and tear questions in another mail
sometime as many people only answer one question per mail :-)
Thanks
Richard Holder with an efficiency hat on !
Message 4
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| Subject: | Re: Changing Coolant |
"When you go back to 50/50 you need to lower your max coolant temp to
248F. If you don't have a coolant gauge then watch the CHT temps as
they are very close.
You never said why you wanted to change? If you don't have a temp
issue why change."
I have a small leak in the radiator which I am fixing and I thought
it would be a good time to change to antifreeze as my summer CHTs
were higher than I like them to be. I understand that using
antifreeze could lower them 10 to 20 degrees.
Thanks for the the replies to my question on coolant.
Mike
Do not archive
Message 5
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| Subject: | Re: Setting prop pitch |
Richard,
To save you the bother, the maximum efficiency of any engine is at maximum
torque speed and WOT. So that will be somewhere between 4800rpm and 5200 rpm
for the 'S' (Rotax's figures have varied somewhat over the years on this!).
At less than WOT, efficiency falls off anyway and, within limits, there is
no point extracting the x% of required power at a higher engine speed than
necessary, because there is a price to pay for the additional mechanical
losses of that higher speed.
Duncan McF.
----- Original Message -----
From: "R Holder" <rholder@avnet.co.uk>
<europa-list@matronics.com>
Sent: Sunday, November 02, 2008 1:50 PM
Subject: RotaxEngines-List: Setting prop pitch
>
>
>> Set the prop to 5500 WOT flat and level, but that is
>> not where you cruise. When the prop is set to 5500 you
>> benefit from the prop pitch during other times such as
>> in takeoff with better climb performance, lower
>> throttle setting for cruise means a little better fuel
>> economy. If it is set for 5500 and lets say you bounce
>> up off the runway and you go "oh no I'm going to drop
>> it in", then when you give it full throttle trying to
>> save yourself the engine will spin up faster to save
>> you, compared to, if you had too big a bite of air with
>> the prop and it had to struggle to spin up. If the prop
>> is pitched too much you will need to give it more
>> throttle/fuel to achieve your cruise speed. When it is
>> set for 5500 you will be able to pull back on the
>> throttle/less fuel and still cruise at the speed you
>> want. You will have a higher top end speed, too. Mind
>> you we are comparing 5500 to your 4800 here. A 700 rpm
>> gain will make a big difference. I know some that
>> cruise at 5500 WOT just to cruise. This will cause
>> extra wear over time. My question is why? Do you need
>> to get somewhere a few miles per hour faster all the
>> time? Why wear and tear any extra on the engine than
>> need be. We want it to be reliable for its 1500 hours
>> and more.
>
> I think you need to stress (I think this is right) that
> the 5500 WOT is static, on the ground. The rpm for WOT in
> the cruise will depend on a number of factors.
>
> But i would like to ask if anyone has a 912S/ULS with an
> airmaster prop and a MAP guage _AND_ a fuel flow meter.
>
> Could they do an experiment for me ! Chose a specific
> airspeed (X) at around your normal cruise speed. I would
> use 115 knots on my plane.
>
> Now there are a number of combinations of rpm and MAP that
> will achieve that airspeed. I use 25 inches and 4600.
>
> The experiment is to set different rpms; and for each
> adjust the MAP so that the airspeed is X (stabilised).
> Then for each combination of rpm/MAP record the fuel flow
> - ideally to the tenth of a litre but a tenth of a US
> gallon would be OK.
>
> As the engine must be producing the same horsepower as it
> is travelling at the same speed for each combination, any
> variation in the fuel flow is a measure of the efficiency
> of the engine. If the efficiency is the same for the whole
> rpm range tested then the fuel flow would be the same. So
> a "scientific" test will show any variation and maybe
> there will be an obvious peak to the efficiency - this
> will be where the fuel flow is least.
>
> According to Roger's recent postings the implication is
> that this peak efficiency rpm/MAP combination will be at
> or around 5000 rpm.
>
> If several people are able to do this, please post results
> direct to me so that I can collate independently :-) The
> critical factor here is that the MAP must be adjusted to
> get the same airspeed (X) for each rpm figure tested.
>
> So the results might look like the following
>
> at 115 knots
> 4500 26 15.8 (15.8 would be the litres per hour fuel flow)
> 4600 25 15.5
> 4700 24.5 15.5
> 4800 24 15.3
> 4900 23.5 15.1
> 5000 23.1 15.0 <------ B E S T E F F I C I E N C Y
> 5100 22.8 15.2 O N T H E S E T E S T F I G U R E S
> 5200 22.4 15.4
> 5300 22.1 15.5
>
> It would be something to pass the time on your next two hour flight !
>
> And if you had longer, other speeds could also be tried - X+10 and X -10 !
>
> I will ask the wear and tear questions in another mail
> sometime as many people only answer one question per mail :-)
>
> Thanks
>
> Richard Holder with an efficiency hat on !
>
>
>
Message 6
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| Subject: | Re: Changing Coolant |
I had temps drop in excess of 50 degrees when changing from Evans to 50/50 glycol-water
mix. My EGT dropped even more than that. I am not a fan of the Evans
coolant. I know Prestone makes the "Dexcool" antifreeze that states on the
jug that it is specifically designed to be used in aluminum systems.
--------
Darin Hawkes
Series 7 (Phase 1 - Flight Testing)
914 Turbo
Kaysville, Utah
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=211774#211774
Message 7
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| Subject: | Re: Rotax Oil Filter |
Pete,
The Napa and STP appear to be the same length as the Fram at least when cross referencing
to the same filter. Do you have filter numbers for the Napa and STP
so I can verify if they will indeed fit?
--------
Darin Hawkes
Series 7 (Phase 1 - Flight Testing)
914 Turbo
Kaysville, Utah
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=211775#211775
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| Subject: | Re: gear box insp. |
If you have an experimental airworthiness cert, you or anyone
can do the gearbox inspection. It does require some tooling, a press,
and it would be unwise to perform without taking one of the rotax
courses in which the technique is taught. I recommend Dean's
course at Sebring (aerotechnicalinstitute.com)
As for price for sending the work out, call your local authorized
Rotax repair center. Don't ask here, it varies around the country.
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=211786#211786
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| Subject: | Re: gear box insp. |
Wow, I wonder about "anyone" can do the inspection.
John Cox
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of
rampil
Sent: Sunday, November 02, 2008 9:06 AM
Subject: RotaxEngines-List: Re: gear box insp.
If you have an experimental airworthiness cert, you or anyone
can do the gearbox inspection. It does require some tooling, a press,
and it would be unwise to perform without taking one of the rotax
courses in which the technique is taught. I recommend Dean's
course at Sebring (aerotechnicalinstitute.com)
As for price for sending the work out, call your local authorized
Rotax repair center. Don't ask here, it varies around the country.
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=211786#211786
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| Subject: | Re: setting prop pitch |
See the torque chart attached. (Top One)
Max torque is 5000 rpm after that torque goes down and HP climbs.
There is no magic here just the best compromise.
Set your prop to get 5500 engine rpm at WOT in the air flat and level. At this
setting you will have the best setting for you average pilot and plane. Most of
us do not need special prop settings like maybe a float plane.
This is not hard, don't make it hard.
I have a Dynon system and have all the info.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Service Center
520-574-1080
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=211845#211845
Attachments:
http://forums.matronics.com//files/rotax_in_word_161.doc
Message 11
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| Subject: | Re: gear box insp. |
The 600 hr is not the gearbox inspection, but the overload clutch. You can not
do this yourself and will only bend your engine mounts. You will need bracing
for the engine, a special 5' tool and lever. I hate to say this in writing, but
you may want to forgo this if you have no one in your area to do this check,
or fly your plane to a distributor, but ask them first if they can handle this
inspection..
If you are using 91 octane then you don't need to do this inspection at this time.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Service Center
520-574-1080
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=211849#211849
Message 12
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| Subject: | Re: Free Wheeling Prop |
Dale, I have a 912ul (about 100hrs time) on a kitfox and have had a similar problem
the last 2 days. The first time (11/1) I just hand turned the prop and
started getting compression about every 3rd blade and kept this up until I could
"burp" the oil tank. I then tried starting again and finally it fired but
ran very rough for a few minutes before settling down. Then today (11/2) I hand
rotated prop and again..no compression at all..this time I removed spark plugs
one at a time and rotated prop and it may have been a coincidence, but after
removing the first plug which was the bottom on cylinder number 3 (i think)
once again I had compression about every 3rd blade. I went ahead and removed the
other spark plugs one at a time, rotated prop and then re-installed plugs and
nothing else changed..still compression about every 3rd blade. Spark plugs
were fine as they were recently replaced (3hrs). Again, when starting the engine
ran rough a couple of minutes but smoothed up to normal (a little quicker today
than yesterday). Have you found anything else out about your problem? I really
don't think I did anything to correct my problem other than turning the
prop over and letting it sit a few minutes? Anybody else with ideas/experiences
would be appreciated.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=211851#211851
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| Subject: | Re: setting prop pitch |
Roger,
A question remaining is at what altitude do you do the 5500 WOT?
Above 5000 ft I use WOT as the max power is down to 75% at that height.
There is another factor.. What is the optimum rotational speed of a given
propeller?
Dave Austin 601HDS - 912
Message 14
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| Subject: | Re: Free Wheeling Prop |
Hi Guys,
I talked to a Rotax mechanic in Phoenix and he said that carbon deposits on the
valves can cause the "no compression" effect when hand propping. He recommended
using Marvel Mystery Oil to the fuel to remove Carbon deposits. The previous
owner of my plane always used auto fuel and the plane sat for long periods
with the sludge from auto fuel building up. Since I'm not sure what I'm getting
with Auto fuel I decided to use 100LL Avgas, add Mystery oil & change oil
& filter every 25 hrs. I'm also adding Decalin to the Avgas. I was also told to
run the engine hard for awhile when using Avgas. I'm using Aeroshell Plus 4
oil. The way I see it spending a little more $$$$ for Oil & additives is cheaper
than an early Engine Overhaul. I guess time will tell if this works.
Dale
--------
Dale
KitFox 7
Las Vegas, Nv
daleorth@embarqmail.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=211882#211882
Message 15
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| Subject: | Re: gear box insp. |
Hi Bob,=0A=0AI seem to recall when mine came due I sent it to Lockwood. Th
ey turned it around in less than a week and I think it was less than a coup
le of hundred dollars.=0A=0ARegards, Paul=0A=0A=0A=0A=0A__________________
______________=0AFrom: "airgriff@surferz.net" <airgriff@surferz.net>=0ATo:
rotaxengines-list@matronics.com=0ASent: Sunday, November 2, 2008 8:30:58 AM
=0ASubject: RotaxEngines-List: gear box insp.=0A=0A =0AGood morning =0Aguys
,=0ADoes=0Aanyone know the requirements for the 912 gear box inspection at
600 hrs. ?=0ASomeone told us it requires going to a Rotax repair center and
costs around 6=0Aor $ 800 ?, and that an A&P can=A2t do it ?=0ABob=0AGriff
=========0A=0A=0A=0A
Message 16
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| Subject: | Re: setting prop pitch |
When I set someone's prop so the engine turns 5500 I always ask at what altitude
they fly at the majority of the time. (i.e. some say between 1k-3k, some say
7k-9k). This is the altitude you set the prop for. Whatever they fly at the majority
of the time and don't worry about the percentage outside your norms. You
will have a slightly flatter pitch prop for the guy that flys at 8k-10k over
the guy that flys at 1k-2k. You want your engine to be able to run at it's best
HP rating and best torque for your normal everyday flying. Mine is set up
for 3k-5k in altitude. Remember a ground adjustable prop setup is a compromise
trying to get the best performance at a specific setting for all flights. (it
can't be made perfect for all scenarios)
The props on the market and Mfg's that have props for the Rotax 912's know what
the Rotax turns for rpm so set your prop for the correct engine rpm for the best
combination. This is also a compromise.
Try it, if you don't like it change it back.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Service Center
520-574-1080
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=211919#211919
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