Today's Message Index:
----------------------
1. 02:24 AM - Re: Re: Why exactly shouldn't you run a 914 without a prop? (Gilles Thesee)
2. 06:47 AM - Re: Why exactly shouldn't you run a 914 without a prop? (lucien)
3. 07:07 AM - Re: Re: Why exactly shouldn't you run a 914 without a prop? (Chris Blackmore)
4. 10:51 AM - Re: Re: Why exactly shouldn't you run a 914 without a prop? (Scott Schmidt)
5. 11:23 AM - Re: Re: Why exactly shouldn't you run a 914 without a prop? (Bob Borger)
6. 12:04 PM - Re: Re: Rotax 914 with 160HP! (jason Parker)
7. 01:03 PM - Re: Re: Rotax 914 with 160HP! (John Cox)
8. 01:45 PM - Rotax 912/914 Mechanical Fuel injection (Catz631@aol.com)
9. 02:20 PM - Re: Re: Why exactly shouldn't you run a 914 without a prop? (FLYaDIVE)
10. 05:46 PM - Re: Re: Why exactly shouldn't you run a 914 without a prop? (Dave G)
11. 06:45 PM - Re: Re: Why exactly shouldn't you run a 914 without a prop? (Gilles Thesee)
Message 1
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| Subject: | Re: Why exactly shouldn't you run a 914 without |
a prop?
Hi Ron,
> Was turning over my 914 today to move around a little lubrication and figure
I should make the point that the Rotax 914 does in fact have a flywheel. Gilles
a while back you posted a picture of a crankshaft stating there is no flywheel.
You didn't mention the picture that attaches to the aft (opposite the prop)
end. #19 which is called by Rotax the Flywheel hub, and #1 Magnito ring that
is a big hunk of metal that is attached to the outside OD of Flywheel hub. Together
these components are in fact a substantial piece of rotating mass (flywheel).
You are referring to the Rotax alternator, which certainly plays a role
in torsional vibration modes, but its inertia cannot be compared to that
of a prop.
An engine doesn't just need "a flywheel".
Its torsional modes are subject to rigorous testing and adjustments
before it can achieve reliability. Most backyard mechanics don't have
the equipment to make the appropriate measurements and prolonged bench
fatigue tests, so better follow the manual's dos and don'ts.
> That said if you were to mount a 914 on a motorcycle, it would probably be OK
as is, but for easier drivability, you may want more flywheel when operating
at lower RPMs.
> For sure if you used a new engine it would be one costly motorcycle!
>
Running it against the manufacturer advice might make it an expensive
aircraft engine as well ;-)
Best regards,
--
Gilles
http://contrails.free.fr
Message 2
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| Subject: | Re: Why exactly shouldn't you run a 914 without a prop? |
Gilles.Thesee(at)ac-greno wrote:
> AmphibFlyer a crit :
> How do you qualify a "perfectly smooth" idle ?
> My engine also idles perfectly smoothly (with a prop attached, though)
> between 1100 and 1800 rpm, and yet Rotax advises against idling below
> 1400 rpm, due to stress and chatter in the reduction gear, which to date
> I have never been able to detect.
>
>
Like you said, tho, that doesn't mean everything is necessarily ok and there won't
be long-term problems.
In fact, I was in a nasty thread a while back on another group where someone was
advocating a shutdown procedure that introduced the possible hazard of running
the engine below the specified minimum if it weren't carried out just exactly
right. The claim was that it came from Eric Tucker or something like that but
was otherwise backed up with nothing else but that heresay.
My contention is, at 20 large (and continuing to go up) a pop, the 912 is a poor
platform for testing these oddball procedures gotten off the Internet or somewhere,
unless you really have a lot of money to burn.
As for running the 912 series without a prop, it's also very likely that not a
lot of field testing has been done with the 912 in that particular configuration
;).
So basically, these oddball ideas are done at one's own risk, both financially
and in terms of support from Rotax and dealers, etc. On something relatively inexpensive
like an auto or motorcycle engine you're not likely to be out a whole
lot of cash if something breaks, but not with our 912's.
Let's be careful out there,
LS
--------
LS
Titan II SS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294302#294302
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| Subject: | Re: Why exactly shouldn't you run a 914 without |
a prop?
Message 4
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| Subject: | Re: Why exactly shouldn't you run a 914 without |
a prop?
I just joined this group so I can start learning about the Rotax. Just sta
rted an RV-12. =0A=0AI may have missed something discussed earlier about th
is thread, but why would you ever run this motor before mounting it on the
plane with a prop?=0AWhat is the advantage of running it without a propelle
r? When I built my RV-10 I had to be very careful not to bet my CHT's over
200 during my 3 test runs before the first flight. I just made sure the m
ag and ignition system worked, the oil pressure was up and the prop cycled.
But I don't know the break-in procedures for the 912 yet so that is why I
am asking. =0A=0AThanks. =0A=0A Scott Schmidt=0Ascottmschmidt@yahoo.com=0A
=0A=0A=0A=0A=0A________________________________=0AFrom: lucien <lstavenhage
n@hotmail.com>=0ATo: rotaxengines-list@matronics.com=0ASent: Thu, April 15,
2010 7:46:16 AM=0ASubject: RotaxEngines-List: Re: Why exactly shouldn't yo
lucien" <lstavenhagen@hotmail.com>=0A=0A=0AGilles.Thesee(at)ac-greno wrote:
=0A> AmphibFlyer a =EF=BDcrit :=0A> How do you qualify a "perfectly smoo
th" idle ?=0A> My engine also idles perfectly smoothly (with a prop attache
d, though) =0A> between 1100 and 1800 rpm, and yet Rotax advises against id
ling below =0A> 1400 rpm, due to stress and chatter in the reduction gear,
which to date =0A> I have never been able to detect.=0A> =0A> =0A=0A=0ALike
you said, tho, that doesn't mean everything is necessarily ok and there wo
n't be long-term problems. =0AIn fact, I was in a nasty thread a while back
on another group where someone was advocating a shutdown procedure that in
troduced the possible hazard of running the engine below the specified mini
mum if it weren't carried out just exactly right. The claim was that it cam
e from Eric Tucker or something like that but was otherwise backed up with
nothing else but that heresay. =0AMy contention is, at 20 large (and contin
uing to go up) a pop, the 912 is a poor platform for testing these oddball
procedures gotten off the Internet or somewhere, unless you really have a l
ot of money to burn.=0A=0AAs for running the 912 series without a prop, it'
s also very likely that not a lot of field testing has been done with the 9
12 in that particular configuration ;).=0A=0ASo basically, these oddball id
eas are done at one's own risk, both financially and in terms of support fr
om Rotax and dealers, etc. On something relatively inexpensive like an auto
or motorcycle engine you're not likely to be out a whole lot of cash if so
mething breaks, but not with our 912's. =0A=0ALet's be careful out there,
=0A=0ALS=0A=0A--------=0ALS=0ATitan II SS=0A=0A=0A=0A=0ARead this topic onl
ine here:=0A=0Ahttp://forums.matronics.com/viewtopic.php?p=294302#294302
=
Message 5
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| Subject: | Re: Why exactly shouldn't you run a 914 without |
a prop?
Scott,
My answer to your first question is "Darned if I know why anyone would do that."
But I'm sure there are lots of folks out there who would and they can tell
you why they would. Maybe safety when making tests around a running engine?
Best source for initial learning about your Rotax engine is Rotax-Owners.com. Go and sign up. Then hit the downloads page and download every document pertinent to your engine; owners manual, maintenance manual, etc. If you pay the big buck for membership, you can have access to some good video courses on the engine. I'd also recommend you attend one of the Rotax owners/maintenance courses that are offered around the country. I took the one at Lockwood Aviation in Sebring Florida. They are very good sources of information and practices. You can check my Europa builders site ( http://www.europaowners.org/forums/gallery2.php?g2_itemId=60232 ) for my gallery on the course I attended.
The Rotax engines are fine little machines but they do have their own ways and
you want to treat them like Rotax engines and not Continental or Lycoming engines.
Good luck and have fun building and flying your RV-12,
Bob Borger
Europa XS Monowheel, Intercooled Rotax 914, Airmaster C/S prop - Flying
Little Toot Sport Biplane, Lycoming YIO-320, Sensenich wood prop - under construction
On Thursday, April 15, 2010, at 12:43PM, "Scott Schmidt" <scottmschmidt@yahoo.com>
wrote:
>
Message 6
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| Subject: | Re: Rotax 914 with 160HP! |
I make 170 HP. Take a 912s drop the pistons out and put a set of my forged
9:1 compression pistons in with a turbocharger and direct port fuel injecti
on. Boost 7.5 PSI and you got it.
Jason
Don't believe me take a look at the these videos
http://www.youtube.com/user/RotaxKing#p/u/0/BXNZRiFd9oI
http://www.youtube.com/user/RotaxKing#p/u/1/R3fBIIO7WAY
--- On Wed, 4/14/10, rparigoris <rparigor@suffolk.lib.ny.us> wrote:
From: rparigoris <rparigor@suffolk.lib.ny.us>
Subject: RotaxEngines-List: Re: Rotax 914 with 160HP!
.ny.us>
Hi Rick
I posted some of the notes TIC > but not completely.
I own two BMW Isettas. They incorporate Dynamos, put power in and they are
a 1 to 1 electric motor for starting, reverse leads and then becomes a char
ger.
There is no speak of what electrical source they are using, but for certain
it comes at a weight penalty. If you have 40 HP available and use it for s
tarting, I don't care if you have a 5 to 1 ratio, it is going to crank a fa
irly low compression 4 cylinder 1.2 liter engine. I forget the watt output
of starter motor, but think it less than 1 HP. I mention that the prop hub
is not connected directly to gears but it is in fact connected. The dogs an
d pretensioned thrust springs "give", but not too much. Just like you can t
urn motor by hand from the prop, unless the electric motor has a spraigue t
ype clutch I don't see any reason it would not function as a starter. The p
roblem I do see is you need electronics so it doesn't spin things too fast
at first with low oil pressure. Nothing a PWM ESC couldn't easily handle. t
hey are now very "smart", not requiring sensors and vary timing to mapped c
onfiguration using RPM and load as factors.
It is a concept I think perhaps could have some validity. For instance lets
take a 80HP 912. Not the most peppy motor for short field take offs if pit
ched for cruise. Lets keep things simple and keep fixed pitch prop, find a
15 to 20 HP 3 phase brushless motor and use the electric motor for take off
s. Need be only 2 to 3 minutes that would allow 5750 RPM, kinda like a pseu
do CS prop. Since the duty cycle is limited perhaps could use a very small
motor that spins up high RPMs. Now with technology fastly moving lets say w
e use something like- Aerogel super capacitors for power. If you were abl
e to get rid of starter motor weight may not be too bad.
True you don't get something for nothing, but once in cruise could use that
motor to charge capacitors and aid meek internal generator capability.
Guess it should be called a 913DBMN- (D for Dream But Maby Not)
When prototypes prove feasible, a integral starter, charger, WEP (War Emerg
ency Power) unit could be fit to the end of crankshaft instead of current g
enerator/flywheel.
Ron Parigoris
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294288#294288
le, List Admin.
=0A=0A=0A
Message 7
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| Subject: | Re: Rotax 914 with 160HP! |
Jason, What fuel are you running? It won't be Oregon Mogas E-85. Do
you have any knock sensors? Can you Turbo Normalize and why not use the
914 with the Rotax Turbo as a base block?
John Cox
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of jason
Parker
Sent: Thursday, April 15, 2010 12:03 PM
Subject: Re: RotaxEngines-List: Re: Rotax 914 with 160HP!
I make 170 HP. Take a 912s drop the pistons out and put a set of my
forged 9:1 compression pistons in with a turbocharger and direct port
fuel injection. Boost 7.5 PSI and you got it.
Jason
Don't believe me take a look at the these videos
http://www.youtube.com/user/RotaxKing#p/u/0/BXNZRiFd9oI
http://www.youtube.com/user/RotaxKing#p/u/1/R3fBIIO7WAY
--- On Wed, 4/14/10, rparigoris <rparigor@suffolk.lib.ny.us> wrote:
From: rparigoris <rparigor@suffolk.lib.ny.us>
Subject: RotaxEngines-List: Re: Rotax 914 with 160HP!
To: rotaxengines-list@matronics.com
Date: Wednesday, April 14, 2010, 9:18 PM
<rparigor@suffolk.lib.ny.us
<http://us.mc1114.mail.yahoo.com/mc/compose?to=rparigor@suffolk.lib.ny.
u
s> >
Hi Rick
I posted some of the notes TIC > but not completely.
I own two BMW Isettas. They incorporate Dynamos, put power in
and they are a 1 to 1 electric motor for starting, reverse leads and
then becomes a charger.
There is no speak of what electrical source they are using, but
for certain it comes at a weight penalty. If you have 40 HP available
and use it for starting, I don't care if you have a 5 to 1 ratio, it is
going to crank a fairly low compression 4 cylinder 1.2 liter engine. I
forget the watt output of starter motor, but think it less than 1 HP. I
mention that the prop hub is not connected directly to gears but it is
in fact connected. The dogs and pretensioned thrust springs "give", but
not too much. Just like you can turn motor by hand from the prop, unless
the electric motor has a spraigue type clutch I don't see any reason it
would not function as a starter. The problem I do see is you need
electronics so it doesn't spin things too fast at first with low oil
pressure. Nothing a PWM ESC couldn't easily handle. they are now very
"smart", not requiring sensors and vary timing to mapped configuration
using RPM and load as factors.
It is a concept I think perhaps could have some validity. For
instance lets take a 80HP 912. Not the most peppy motor for short field
take offs if pitched for cruise. Lets keep things simple and keep fixed
pitch prop, find a 15 to 20 HP 3 phase brushless motor and use the
electric motor for take offs. Need be only 2 to 3 minutes that would
allow 5750 RPM, kinda like a pseudo CS prop. Since the duty cycle is
limited perhaps could use a very small motor that spins up high RPMs.
Now with technology fastly moving lets say we use something like
Aerogel super capacitors for power. If you were able to get rid of
starter motor weight may not be too bad.
True you don't get something for nothing, but once in cruise
could use that motor to charge capacitors and aid meek internal
generator capability.
Guess it should be called a 913DBMN (D for Dream But Maby Not)
When prototypes prove feasible, a integral starter, charger, WEP
(War Emergency Power) unit could be fit to the end of crankshaft instead
of current generator/flywheel.
Ron Parigoris
Read this topic online here:
http://forums.matronics.com/viewtopic.phpsp; -->
<http://forums.matronics.com/viewtopic.php?p=294288#294288>
http://www.matronics.com/Navigator?RotaxEngines-List<sp; -->
<http://www.matronics.com/Navigator?RotaxEngines-List>
http://www.matronics.com/cont===============
<http://forums.matronics.com/>
Message 8
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| Subject: | Rotax 912/914 Mechanical Fuel injection |
I saw an interesting thing yesterday at Sun-N-Fun. It was a mechanical fuel
injection on a Highlander. They have been testing it for a while and so far
it is working out fine. There are no electrical inputs! It is entirely
mechanical and apparently the design is very similar to the one Lycoming uses as
the same guy developed theirs according to what the guy told me.
The claim in the data sheet is 10-30 % increase in hp, better fuel
metering,etc. I can't locate the flyer right now which talks about all the benefits
of this system as I have a whole bag full of stuff. If anyone is interested
I will send the info on the web site when I find the flyer.
It is a real nice, well made set up and the price was $3800.00 I am sorely
tempted!
Dick Maddux
Fox 4
Milton,Fl
Message 9
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| Subject: | Re: Why exactly shouldn't you run a 914 without |
a prop?
It never ceases to amaze me .... 1.5 Million Years to evolve from
Neanderthal to Modern Man.
And No Matter how many times you tell people the fire is hot - You
will get burned ---
They Just Got To Put Their Hand In The Fire!
What the hell does it prove if YOU can get a ROTAX to run without a prop?
Ya want a pat on the back - - - OK, Here it is. Pat - Pat.
Now, give every one your N-Number and Serial Number of the engine so
they know to stay
away from them when you go to sell.
Barry
On Thu, Apr 15, 2010 at 5:15 AM, Gilles Thesee
<Gilles.Thesee@ac-grenoble.fr> wrote:
> <Gilles.Thesee@ac-grenoble.fr>
>
> Hi Ron,
>>
>> Was turning over my 914 today to move around a little lubrication and
>> figure I should make the point that the Rotax 914 does in fact have a
>> flywheel. Gilles a while back you posted a picture of a crankshaft stating
>> there is no flywheel. You didn't mention the picture that attaches to the
>> aft (opposite the prop) end. #19 which is called by Rotax the Flywheel hub,
>> and #1 Magnito ring that is a big hunk of metal that is attached to the
>> outside OD of Flywheel hub. Together these components are in fact a
>> substantial piece of rotating mass (flywheel).
>
> You are referring to the Rotax alternator, which certainly plays a role in
> torsional vibration modes, but its inertia cannot be compared to that of a
> prop.
> An engine doesn't just need "a flywheel".
> Its torsional modes are subject to rigorous testing and adjustments before
> it can achieve reliability. Most backyard mechanics don't have the equipment
> to make the appropriate measurements and prolonged bench fatigue tests, so
> better follow the manual's dos and don'ts.
>
>> That said if you were to mount a 914 on a motorcycle, it would probably
>> be OK as is, but for easier drivability, you may want more flywheel when
>> operating at lower RPMs.
>> For sure if you used a new engine it would be one costly motorcycle!
>>
>
> Running it against the manufacturer advice might make it an expensive
> aircraft engine as well ;-)
>
> Best regards,
> --
> Gilles
> http://contrails.free.fr
>
>
Message 10
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| Subject: | Re: Why exactly shouldn't you run a 914 without |
a prop?
This started as a question and a conversation and is rapidly becoming
something ugly. Why do people feel it necessary to "win" a discussion?
The first couple of replies identified the potential downside of operating
the engine without a prop and so does the install manual, there is no
mention of operation sans prop in the operation manual that I could find.
Here is every instance of operation without propeller I can find in the
manual:
- Never run the engine without a propeller as this will inevitably cause
engine damage and present a hazard of explosion.
WARNING: Never run the engine without a propeller installed as engine
would suffer severe damage by overspeeding.
That is the sum total of what they have to say on the matter. Clearly an
engine operated in a no-load state could quickly overspeed or over-rev if
you like. Beyond that possibilibility, there doesn't appear to much
likelihood of a problem. It's very likely a bad idea because over-revving
can occur quickly, but all this talk of flywheel, torsion, gearbox, etc in a
no load situation doesn't seem likely to me. Indeed the video of one running
at low RPM looked quite happy to me, humming along smoothly. So, can we
agree that it's not a good idea because the engine may over-rev and leave it
at that, no pats or flames required.
----- Original Message -----
From: "FLYaDIVE" <flyadive@gmail.com>
Sent: Thursday, April 15, 2010 6:18 PM
Subject: Re: RotaxEngines-List: Re: Why exactly shouldn't you run a 914
without a prop?
>
> It never ceases to amaze me .... 1.5 Million Years to evolve from
> Neanderthal to Modern Man.
> And No Matter how many times you tell people the fire is hot - You
> will get burned ---
> They Just Got To Put Their Hand In The Fire!
>
> What the hell does it prove if YOU can get a ROTAX to run without a prop?
> Ya want a pat on the back - - - OK, Here it is. Pat - Pat.
> Now, give every one your N-Number and Serial Number of the engine so
> they know to stay
> away from them when you go to sell.
>
> Barry
>
Message 11
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| Subject: | Re: Why exactly shouldn't you run a 914 without |
a prop?
Dave G a crit :
> but all this talk of flywheel, torsion, gearbox, etc in a no load
> situation doesn't seem likely to me. Indeed the video of one running
> at low RPM looked quite happy to me, humming along smoothly. So, can
> we agree that it's not a good idea because the engine may over-rev and
> leave it at that, no pats or flames required.
Dave,
Would you care to share with us the physics beyond your opinion ?
I'm surprised that you make a point of over reving though this situation
can be easily controlled by careful use of the throttle, as has already
been pointed out. Whereas you seem to dismiss torsional vibrations
which need lots of experimenting to take care of.
Some of us have some experience with reciprocating engines, but most
are not equiped -and did not conduct experiments- to decide whether
running without a propeller keeps torsional vibrations within safe
limits or not.
The matter is rather intricate, so if you have some info that we don't
have, please share it with us.
As you may have noticed, even when running out of their safe idle rpm,
Rotax engines do look happy, although detrimental shatter may occur
within the gear train.
So a layman's impression might not be sufficient.
Best regards,
--
Gilles
http://contrails.free.fr
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