Today's Message Index:
----------------------
1. 08:37 AM - Re: Fuel consumption for the 912S (John Goodings)
2. 09:06 AM - Re: Re: Why exactly shouldn't you run a 914 without a prop? (Noel Loveys)
3. 09:08 AM - Re: Re: Why exactly shouldn't you run a 914 without a prop? (Gilles Thesee)
4. 09:14 AM - Re: Re: Fuel consumption for the 912S (Gilles Thesee)
5. 11:34 AM - Re: Why exactly shouldn't you run a 914 without a prop? (rparigoris)
6. 01:29 PM - Re: Why exactly shouldn't you run a 914 without a prop? (rparigoris)
7. 03:15 PM - Re: 912s motor mount question (Guy Buchanan)
8. 03:52 PM - Re: Why exactly shouldn't you run a 914 without a prop? (lucien)
9. 07:06 PM - Desser 4.00-6 8 ply and 6 ply LSA tire (Roger Lee)
Message 1
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| Subject: | Re: Fuel consumption for the 912S |
People have been quoting fuel consumption figures for the Rotax 914
recently. The figures quoted seem rather high. What fuel consumption do
people get with the Rotax 912S (100 HP)? We have measured it pretty
carefully over quite a number of hours, and we are getting slightly under
16 litres/hr (4.34 U.S. gal/hr) at 5200 RPM cruise. We use mainly 91
octane mogas without ethanol additive, but probably 1/3 of the fuel used
is 100 LL because we don't have a choice at many small airports in
Ontario. Here are other details of our aircraft, but I'm not sure they
are very relevant to fuel consumption. Our aircraft is a CH601HD with a
66-inch, 3-blade, GSC prop flying with 2 people (and 1 small Italian
greyhound!) near 1200 lbs gross weight. Because of that thick wing, our
cruise is only about 100-105 mph.
John Goodings, C-FGPJ, CH601HD with R912S, Carp/Ottawa/Toronto.
Message 2
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| Subject: | Re: Why exactly shouldn't you run a 914 without |
a prop?
Lucien:
Dave has a video up on you tube where he hand props a 582 in the middle of
winter up to his backside in snow. While rotax has good pull cord starters
they have to come off to put on the standard electric starter. Being able
to hand prop a plane can be literally a life saver on a cold Ontario day.
Noel
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of lucien
Sent: April 17, 2010 12:36 PM
Subject: RotaxEngines-List: Re: Why exactly shouldn't you run a 914 without
a prop?
dave wrote:
> Not able to hand prop
> extra parts that "could " give troubles
>
> giant airbrake
>
>
> ---
Er, that hardly qualifies as a large set of cons outweighing the (much
larger) set of pros of using the RK-400 clutch.
Like I said, most of the folks who go on about how worthless the clutch is
have very little, if any, time on a clutch-equipped engine/airplane.
No hand propping is a good try, but I'm not too convinced - the Rotax
2-strokes come with an excellent pull-rope starting system that is very
reliable and gives little trouble. Even if, say the rope pulls out of the
handle, the pull start is easily fixable in the field with a few hand tools
you can keep in your flight bag. So it'd be rare indeed that you'd have to
resort to hand starting (a very dangerous proposition on many pusher designs
anyway).
If you put a mag-end electric start on Rotax 2-stroke, you get what you
deserve anyway. At that point you should have gone with the E box which
addresses that concern already.
I totally don't buy the extra-trouble argument. The RK-400 is a very well
designed, heavy-duty item that lasts simply forever. On my FSII, the
original engine was starting to wear out (at about 400 hours) before even a
few _thousandths_ had been worn off the original set of shoes (I still have
them out in the hangar in fact). The RK-400 was tested on the 618 and
couldn't be made to slip or otherwise give any trouble at all even on that
huge monster.
The giant airbrake argument is another I get all the time from folks who
don't run the clutch. They don't realize, for example, that when the clutch
is disengaged in the air (engine-idle), the plane flies _exactly_ as it
would with the engine off. So you can _exactly_ replicate the engine off
situation in your emergency procedure practice without having to shut the
engine down. This makes getting familiar with the engine-off glide much
safer to practice - i.e. if you really do happen to screw up an approach
during practice you're not in a real emergency if you can't get the cold
engine started again.
So on that day when the engine actually does stop for real, you're not
dangerously trying to stretch a glide you've hardly ever practiced in the
case of a fixed prop. Instead, it's exactly the same condition you've
already practiced a million times before, greatly increasing your chances of
a successful descent and landing.
Sorry, don't buy this one either ;)
LS
--------
LS
Titan II SS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294535#294535
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| Subject: | Re: Why exactly shouldn't you run a 914 without |
a prop?
Hi Ron,
> I will use on my 914 series with bypass fuel systems, with added
> Europa twist of adding a second Andair 375 Gasculator to allow second
> pump to have ability to draw from another source. I willl only use
> Wacker spark plug thermal conductive compound.
Add to that adequate cooling of the engine, with a correctly designed
cooling duct and cowl flap.
> I will check Carbon Monoxide levels above 100% power. I will if my
> life were threatened by the wastegate opening, would follow DO
> procedure in operators manual to leave it closed until obsticle is
> cleared.
Concerning the wastegate ensure good lubrication, and monitor the MP
during the takeoff run and initial climbout. In our project, when
operating from a low level aerodrome, takeoff takes place about 10
seconds after releasing the brakes and power reduction to 100% about 5
seconds later.
> I can go on and on, but if anyone is not following the above procedure
> does it make them unsafe or putting life and engine at risk? If you
> don't follow Mfgs. procedure perhaps the answer perhaps is yes,
> perhaps no, need to take on a case by case basis. Rotax is not an
> absolute advocate of only flying a 914 with a differential pressure
> gauge IMHO they should be.
The initial subject was avoiding mishandling of the engine.
Yes monitoring the fuel pressure could add to the pilot's peace of mind,
but it has no influence on the running of the engine. We monitor FF
during takeoff.
> BTW, did you ever verify with Carbon Monoxide test as suggested or
> required by Rotax (older serial number engines and if you have a
> Intercooler it is a requirement) that you are running rich enough on
> all 4 cylinders above 100% power? If you didn't use Carbon Monoxide
> detector, how did you verify?
Will verify if it applies to our engine. For the time being, plugs seem
to be OK.
Best regards,
--
Gilles
http://contrails.free.fr
Message 4
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| Subject: | Re: Fuel consumption for the 912S |
John,
>
> People have been quoting fuel consumption figures for the Rotax 914
> recently. The figures quoted seem rather high.
About 21 litre/h is quite normal for a 100 hp engine cruising at 75%, be
it a Rotax, a Jabiru or a Lyco/Conti.
> What fuel consumption do people get with the Rotax 912S (100 HP)? We
> have measured it pretty carefully over quite a number of hours, and we
> are getting slightly under 16 litres/hr (4.34 U.S. gal/hr) at 5200 RPM
> cruise.
16 L/h corresponds to about 60% power with a 100 hp.
Are you talking of *cruise* consumption, or overall consumption ? If you
are doing much circuit work, low numbers are normal, since you are most
of the time at part throttle.
Best regards,
--
Gilles
http://contrails.free.fr
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| Subject: | Re: Why exactly shouldn't you run a 914 without a prop? |
Hi Gilles
"Yes monitoring the fuel pressure could add to the pilot's peace of mind,
but it has no influence on the running of the engine. We monitor FF
during takeoff."
Lack of differential fuel pressure on take off leads to "running" of the pilot
when engine plays mellow song of "silent night". You need between ~ 2 and 5 PSI
differential. If low you could get proper fuel flow but on verge of not being
able to meet crack pressure of fuel pressure regulator. Problem is if you have
full float bowls and begin take off run, you will be in air with perhaps not
enough runway to land on when they run out. Also when cruising it gives you
a heads up to close at hand failure. Most culprits of low differential pressure
is clogged fuel filter or gasculator/s. If you reduce power and can attain 2
PSI then you could probably gain yourself a little more time. At altitude where
the pumps have to work hardest are where you will first see lower readings,
a lower altitude may allow you to reach airport. Running lean at altitude is
a very bad thing to do, fuel flow may be fine at less than 2 PSI, but go too much
lower and fuel flow will suffer. Differential can give you a heads up to problem
before it happens.
Ron Parigoris
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294863#294863
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| Subject: | Re: Why exactly shouldn't you run a 914 without a prop? |
Heres someone else running without a prop. No question it revs quickly, but not
unlike many motorcycles:
http://www.youtube.com/watch?v=tUrFJi93MIo
Jason, is this you?
Ron Parigoris
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http://forums.matronics.com/viewtopic.php?p=294872#294872
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| Subject: | Re: 912s motor mount question |
At 09:59 AM 4/18/2010, you wrote:
>I am still having a fight with the water pump being in the way.
Being in the way of what? Can you provide pictures? (Please make them small.)
Thanks,
Guy Buchanan
San Diego, CA
K-IV 1200 / 582-C / Warp / 400 hrs. and counting
Message 8
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| Subject: | Re: Why exactly shouldn't you run a 914 without a prop? |
Float Flyr wrote:
> Lucien:
>
> Dave has a video up on you tube where he hand props a 582 in the middle of
> winter up to his backside in snow. While rotax has good pull cord starters
> they have to come off to put on the standard electric starter. Being able
> to hand prop a plane can be literally a life saver on a cold Ontario day.
>
> Noel
>
> --
Well, for sure if you need to be able to hand prop, no, you don't want to install
the clutch. And FWIW, the clutch does have some down sides so it's not a one-size-fits-all
addition.
I've always flown pushers and so they weren't ever very safe to hand start. But
there was also room for the pull start too, so I wasn't in the situation of say
the Kitfox. But I'd usually carry a spare rope and some extra tools enough
to be able to do a field fix of a starter if the rope pulled out or something
like that.
One time the handle pulled off the end of the rope on my quicksilver. luckily there
was already a knot in the rope a little further downstream so it didn't suck
the rope all the way into the housing. Whew... I tied another knot and took
off....
LS
--------
LS
Titan II SS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294894#294894
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| Subject: | Desser 4.00-6 8 ply and 6 ply LSA tire |
Hi All,
I had a nice and pleasant chat with a Desser supervisor today. After installing
these tires (4.00-6 8 ply) on a few of different aircraft here is what I have
found and discussed with Desser. First these tires do not come pre-balanced and
you will need to do that with some of the stick-on weights. It takes about
1.25 oz. of weight to balance these. I used the 1/4 oz. weights. I put some on
the inside and out side of the wheel. No big sweat they balance right up in a
couple of minutes.
Here is the big discussion. We started off with 30 psi on the 4.00-6 8 plys. At
30 psi these tires seem to have a flat spot and were all bad tires. Not so fast
Hass!
Talking to Desser these tires are not meant to run that low. The pressure of 29
psi was for the original CT tires. They prefer to have at least 62 psi in these
tires if possible. That is little too much for us so we decided on 55-57 psi
and this took the so called flat spot out of the tire. These tires are absolutely
dependent on having enough psi to keep them nice and round. Even with this
if you hold a straight edge up to them they seem ever so slightly off. So I
went out and checked 3 other aircraft with other tires and found exactly the
same thing. No tire is 100% round and is dependent on the proper pressure to maint
that roundness. The less pressure under the recommended the worse it became.
It is the same for the 6 plys and other brands of tires from what I can find.
When you balance these tires and inflate them to 55 psi you will not have
any issues with vibration. I check my 6.00-6 tires and others and they were the
same even though I didn't have to balance them. I am trying hard to get Desser
to pre-balance these tires like they do the larger tires and I believe we have
a good shot at this happening. I'll keep you informed as I do a little more
research for Desser and get some feed back.
These seem to be good tires, but need proper inflation. How much psi are the old
Italian Mark Engegno wheels good for, I don't know.
Like they used to say:
Stay tuned and don't touch that dial!
If your old you'll remember this saying and if you don't then you probably don't
remember Might Mouse either. [Laughing]
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
520-574-1080
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294919#294919
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