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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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 Posted: Thu Dec 31, 2009 7:13 pm Post subject: Rotax 914 Won't Start |
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Barry, Where did you get this procedure? It's not in any Rotax manual.
Rick Girard
On Thu, Dec 31, 2009 at 4:05 PM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
[quote]Rich:
I asked the same question. The procedure is the same as for direct drives. Why you may ask?
Because the prop has more an effect as the FLYWHEEL having a much larger diameter than the gears.
The procedure is this:
1 - Take all safety precautions.
2 - Put the prop on with only a few bolts
3 - Remove the #1 Cyl Spark Plug.
4 - Rotate the prop so #1 piston is TDC on compression stroke.
5 - The prop #1 Blade ... Should be at the 1 O'clock position - LQQKing at it from the front of the engine.
6 - Position and reassemble as required.
Barry
On Thu, Dec 31, 2009 at 3:54 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
| Quote: |
Barry, Rotax engines run a gearbox of either 2.27 or 2.43 ratio. How exactly are you going to CLOCK it?
Rick Girard
On Thu, Dec 31, 2009 at 2:32 PM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: |
Gilles is right 100%!
You should NEVER run an engine without some form of flywheel. A prop IS a flywheel. And if your friend ran an engine without a flywheel and is alive to talk about it he is either lucky or a liar.
An engine run without a flywheel or the proper size flywheel can JUMP into a RUNAWAY condition and reach RPM's so high the engine will literally tear itself apart / explode.
Another question to throw into the pot: Is the prop properly CLOCKED? If it is not in the correct position you will get rough running and vibration.
Barry
On Thu, Dec 31, 2009 at 2:51 PM, AmphibFlyer <SeaRey(at)abstractconcreteworks.com (SeaRey(at)abstractconcreteworks.com)> wrote:
| Quote: | --> RotaxEngines-List message posted by: "AmphibFlyer" <SeaRey(at)AbstractConcreteWorks.com>
Gilles.Thesee(at)ac-greno wrote:
| Quote: | Rotax engines have NO flywheel... Running a Rotax without a prop is a no-no.
|
Well, you're right, mostly. I shouldn't have said that they do. On the other hand, the Heavy Maintenance Manual discusses "flywheel hub" in several places (July 01/2008, 74-00-00, page 49, page 117, and page 25). It doesn't seem to show a clear diagram of an actual flywheel, though.
Also I should confess that I have never tried to run a 914 without a prop and relied on someone else's testimony, which I can't verify right now. So maybe it can be done and maybe it can't.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=279458#279458
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_blank">www.aeroelectric.com
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nk">www.howtocrimp.com
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lucien
Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM
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| Posted: Thu Dec 31, 2009 7:39 pm Post subject: Re: Rotax 914 Won't Start |
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| Gilles.Thesee(at)ac-greno wrote: |
Rotax engines have NO flywheel.
(and will run smoothly without a prop)
Running a Rotax without a prop is a no-no.
|
They do - the magneto ring doubles as a flywheel on both the 2 and 4 stroke Rotaxen.
And yes the 2 strokes run and idle perfectly with no load on them and I would assume the 912 does too.
LS
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lucien
Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM
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| Posted: Thu Dec 31, 2009 7:45 pm Post subject: Re: Rotax 914 Won't Start |
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| AmphibFlyer wrote: | | Gilles.Thesee(at)ac-greno wrote: | | Rotax engines have NO flywheel... Running a Rotax without a prop is a no-no. |
Well, you're right, mostly. I shouldn't have said that they do. On the other hand, the 912/914 Heavy Maintenance Manual discusses "flywheel hub" in several places (July 01/2008, 74-00-00, page 49, page 117, and page 25). It doesn't seem to show a clear diagram of an actual flywheel, though.
Also I should confess that I have never tried to run a 914 without a prop and relied on someone else's testimony, which I can't verify right now. So maybe it can be done and maybe it can't. |
The hazard would be accidentally overspeeding the engine, probably not that they simply wouldn't run without a load. To turn a prop at 1800 to 2000 rpm still takes a little power so removing the load completely could be a problem even at the normal fully idled setting. Either way, at 20grand a pop, yeah... I think I'd not try to experiment with that 
On the 2-strokes, the throttle slides have to be completely bottomed out in order to idle with no load (my 503's with stock slides could get down to 1800 rpm but that was it).
LS
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lucien
Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM
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| Posted: Thu Dec 31, 2009 8:01 pm Post subject: Re: Rotax 914 Won't Start |
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[quote="AmphibFlyer"] | lucien wrote: |
Thanks, Lucien! That makes sense, and now I realize that the springs must be in there at least partly to damp the lash in the gears at low rpm. These Rotax engines have a flywheel (and will run smoothly without a prop), so I hadn't considered the flywheel effect of the prop, resonance, and gear lash. Can't say I like the spring solution, but I guess it works most of the time.
What puzzles me is that Rotax apparently hasn't bothered to mention this condition in the maintenance or operator's manuals. At least, I haven't been able to find any mention of it. Nor indications of the sprag clutch problem. |
A regular flywheel is still needed, mostly as a buffer to absorb the variations in speed of the crank, which would otherwise be very large. With only the prop via the gearbox as the flywheel, that thing would hammer the gearbox to bits in nothing flat.......
Rotax probably doesn't describe this as a symptom because it's not always going to be repeatable. With a different prop that's lighter or maybe even one that's heavier, the condition may change. a motor with weak springs may start and run fine in that case. Even motor mounting stiffness can affect this.
And if the prop is enormous and heavy enough, the engine may act like that with perfectly good spring tension (tho it'd have to a huge ginourmous prop most likely ).
Instead they describe the torque limits which are better early warning signs to be checked for anyway. I think you have to be in pretty bad shape spring tension-wise to cause the symptom your friend's motor is exhibiting.....
Still, the rotax gear boxes are, IMO, superbly designed. The dog hub/spring setup actually works wonders at absorbing the pulses and smoothing out the destructive hammering that would otherwise result. It's a maintenance item for sure, but otherwise the boxes really wouldn't work at all and would self-destruct in short order.
But they last quite a long time....
LS
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LS
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Gilles.Thesee(at)ac-greno
Guest
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| Posted: Thu Dec 31, 2009 9:35 pm Post subject: Rotax 914 Won't Start |
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lucien a écrit :
| Quote: |
They do - the magneto ring doubles as a flywheel on both the 2 and 4 stroke Rotaxen.
And yes the 2 strokes idle perfectly with no load on them and I would assume the 912 does too.
|
Lucien,
I'm mystified as to who could have told you such a thing. Are you sure
this person is really a Rotax connaisseur ?
Here is a page with pictures of the little Rotax alternator.
http://contrails.free.fr/elec_ducati_en.php
How could it's inertia compare with that of the prop ?
Unless one has access to considerable engineering experience with Rotax
engines, it is advisable not to do anything forbidden in the engine manuals.
And better yet, why not just read and follow the book ?
Many many old wife's stories in places where few mechanics really have
Rotax experience.
Best regards,
--
Gilles
http://contrails.free.fr
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arno7452(at)bellsouth.net
Guest
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| Posted: Fri Jan 01, 2010 2:03 am Post subject: Rotax 914 Won't Start |
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|
Hey,
Solve this problem with a swap to a big Harley. I know a bunch of Harley
guys.
Ken
do not archive
---
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lucien
Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM
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| Posted: Fri Jan 01, 2010 6:22 am Post subject: Re: Rotax 914 Won't Start |
|
|
| Gilles.Thesee(at)ac-greno wrote: | Lucien,
I'm mystified as to who could have told you such a thing. Are you sure
this person is really a Rotax connaisseur ?
Here is a page with pictures of the little Rotax alternator.
http://contrails.free.fr/elec_ducati_en.php
How could it's inertia compare with that of the prop ?
Unless one has access to considerable engineering experience with Rotax
engines, it is advisable not to do anything forbidden in the engine manuals.
And better yet, why not just read and follow the book ?
Many many old wife's stories in places where few mechanics really have
Rotax experience.
Best regards,
--
Gilles
http://contrails.free.fr |
The rotax flywheel doesn't compare to that of a prop. It wouldn't need to. it's plenty for the 2-stroke engines to run fine with no load and I would assume the same for the 4-strokes.
My experience with the 2-strokes is direct and not through any connoisseur. I ran the 503 on my Kolb FSII with the RK-400 clutch, which disengages the engine from the gearbox below 2400-2500 rpm. No problems with the engine at those rpms disengaged.
I don't know from direct experience about the 912, so can only speculate about how it would run with only the internal flywheel. I would assume it would run fine, but don't know that for sure.
LS
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Titan II SS |
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Fri Jan 01, 2010 6:26 am Post subject: Rotax 914 Won't Start |
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|
Oh yeah, that's a great idea. What could be a better aircraft engine than the Vibraglide?
Rick Girard
On Fri, Jan 1, 2010 at 3:26 AM, Ken Arnold <arno7452(at)bellsouth.net (arno7452(at)bellsouth.net)> wrote:
[quote]--> RotaxEngines-List message posted by: "Ken Arnold" <arno7452(at)bellsouth.net (arno7452(at)bellsouth.net)>
Hey,
Solve this problem with a swap to a big Harley. I know a bunch of Harley guys.
Ken
do not archive
---
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Roger Lee
Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.
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| Posted: Fri Jan 01, 2010 6:33 am Post subject: Re: Rotax 914 Won't Start |
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900 series engines are never run without a prop. You can damage the engine. It is taught in Rotax schools.
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Home 520-574-1080 TRY HOME FIRST
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flyadive(at)gmail.com
Guest
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| Posted: Mon Jan 04, 2010 8:17 am Post subject: Rotax 914 Won't Start |
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Hi Rick:
HAPPY NEW YEAR!
The procedure is standard for horizontally opposed combustion engines. It is what is being used for both Continental & Lycomming engines. When having a prop balanced it is the first thing checked. I am taking a course on vibration and prop balancing and Chadwick Helmuth and ACES both cover balancing this way. This is done to reduce the amount of balance weight required. Yes, you can balance without doing a static balance but this just helps. It is like balancing tires. Ever see a car with a huge amount of weight required to balance a tire? More than likely they did not place the heavy spot of the tire across from the valve stem.
Barry
On Thu, Dec 31, 2009 at 10:12 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
[quote]Barry, Where did you get this procedure? It's not in any Rotax manual.
Rick Girard
On Thu, Dec 31, 2009 at 4:05 PM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: | Rich:
I asked the same question. The procedure is the same as for direct drives. Why you may ask?
Because the prop has more an effect as the FLYWHEEL having a much larger diameter than the gears.
The procedure is this:
1 - Take all safety precautions.
2 - Put the prop on with only a few bolts
3 - Remove the #1 Cyl Spark Plug.
4 - Rotate the prop so #1 piston is TDC on compression stroke.
5 - The prop #1 Blade ... Should be at the 1 O'clock position - LQQKing at it from the front of the engine.
6 - Position and reassemble as required.
Barry
On Thu, Dec 31, 2009 at 3:54 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
| Quote: |
Barry, Rotax engines run a gearbox of either 2.27 or 2.43 ratio. How exactly are you going to CLOCK it?
Rick Girard
On Thu, Dec 31, 2009 at 2:32 PM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: |
Gilles is right 100%!
You should NEVER run an engine without some form of flywheel. A prop IS a flywheel. And if your friend ran an engine without a flywheel and is alive to talk about it he is either lucky or a liar.
An engine run without a flywheel or the proper size flywheel can JUMP into a RUNAWAY condition and reach RPM's so high the engine will literally tear itself apart / explode.
Another question to throw into the pot: Is the prop properly CLOCKED? If it is not in the correct position you will get rough running and vibration.
Barry
On Thu, Dec 31, 2009 at 2:51 PM, AmphibFlyer <SeaRey(at)abstractconcreteworks.com (SeaRey(at)abstractconcreteworks.com)> wrote:
| Quote: | --> RotaxEngines-List message posted by: "AmphibFlyer" <SeaRey(at)AbstractConcreteWorks.com>
Gilles.Thesee(at)ac-greno wrote:
| Quote: | Rotax engines have NO flywheel... Running a Rotax without a prop is a no-no.
|
Well, you're right, mostly. I shouldn't have said that they do. On the other hand, the Heavy Maintenance Manual discusses "flywheel hub" in several places (July 01/2008, 74-00-00, page 49, page 117, and page 25). It doesn't seem to show a clear diagram of an actual flywheel, though.
Also I should confess that I have never tried to run a 914 without a prop and relied on someone else's testimony, which I can't verify right now. So maybe it can be done and maybe it can't.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=279458#279458
Attachments:
http://forums.matronics.com//files/scr=======
he Contribution link below to find out more about
lder's Bookstore www.buildersbooks.com
href="http://www.howtocrimp.com/" target="_blank">www.howtocrimp.com iption,
www.matronics.com/Navigator?RotaxEngines-List" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
ronics.com/" target="_blank">http://forums.matronics.com
==============
_blank">www.aeroelectric.com
.com" target="_blank">www.buildersbooks.com
="_blank">www.homebuilthelp.com
nk">www.howtocrimp.com
_blank">http://www.matronics.com/contribution
ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
tp://forums.matronics.com
|
|
|
|
| Quote: |
"_blank">www.aeroelectric.com
.com/" target="_blank">www.buildersbooks.com
="_blank">www.homebuilthelp.com
ank">www.howtocrimp.com
_blank">http://www.matronics.com/contribution
ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
ttp://forums.matronics.com
|
[b]
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
|
| Posted: Mon Jan 04, 2010 9:10 am Post subject: Rotax 914 Won't Start |
|
|
Barry, Your mistake here is not recognizing that the 912/914 are GEARED engines. Go to all the trouble to set the prop as you like but the gearing won't bring it back around to that same point for 1071 complete combustion cycles, i.e if you set a very high idle of 2142 RPM the prop would return to your set point once a minute. Lycosaurs are great, but they have so little to do with a Rotax that experience gained with them is virtually useless.
Rick
On Mon, Jan 4, 2010 at 10:06 AM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
[quote] Hi Rick:
HAPPY NEW YEAR!
The procedure is standard for horizontally opposed combustion engines. It is what is being used for both Continental & Lycomming engines. When having a prop balanced it is the first thing checked. I am taking a course on vibration and prop balancing and Chadwick Helmuth and ACES both cover balancing this way. This is done to reduce the amount of balance weight required. Yes, you can balance without doing a static balance but this just helps. It is like balancing tires. Ever see a car with a huge amount of weight required to balance a tire? More than likely they did not place the heavy spot of the tire across from the valve stem.
Barry
On Thu, Dec 31, 2009 at 10:12 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
| Quote: | Barry, Where did you get this procedure? It's not in any Rotax manual.
Rick Girard
On Thu, Dec 31, 2009 at 4:05 PM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: | Rich:
I asked the same question. The procedure is the same as for direct drives. Why you may ask?
Because the prop has more an effect as the FLYWHEEL having a much larger diameter than the gears.
The procedure is this:
1 - Take all safety precautions.
2 - Put the prop on with only a few bolts
3 - Remove the #1 Cyl Spark Plug.
4 - Rotate the prop so #1 piston is TDC on compression stroke.
5 - The prop #1 Blade ... Should be at the 1 O'clock position - LQQKing at it from the front of the engine.
6 - Position and reassemble as required.
Barry
On Thu, Dec 31, 2009 at 3:54 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
| Quote: |
Barry, Rotax engines run a gearbox of either 2.27 or 2.43 ratio. How exactly are you going to CLOCK it?
Rick Girard
On Thu, Dec 31, 2009 at 2:32 PM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: |
Gilles is right 100%!
You should NEVER run an engine without some form of flywheel. A prop IS a flywheel. And if your friend ran an engine without a flywheel and is alive to talk about it he is either lucky or a liar.
An engine run without a flywheel or the proper size flywheel can JUMP into a RUNAWAY condition and reach RPM's so high the engine will literally tear itself apart / explode.
Another question to throw into the pot: Is the prop properly CLOCKED? If it is not in the correct position you will get rough running and vibration.
Barry
On Thu, Dec 31, 2009 at 2:51 PM, AmphibFlyer <SeaRey(at)abstractconcreteworks.com (SeaRey(at)abstractconcreteworks.com)> wrote:
| Quote: | --> RotaxEngines-List message posted by: "AmphibFlyer" <SeaRey(at)AbstractConcreteWorks.com>
Gilles.Thesee(at)ac-greno wrote:
| Quote: | Rotax engines have NO flywheel... Running a Rotax without a prop is a no-no.
|
Well, you're right, mostly. I shouldn't have said that they do. On the other hand, the Heavy Maintenance Manual discusses "flywheel hub" in several places (July 01/2008, 74-00-00, page 49, page 117, and page 25). It doesn't seem to show a clear diagram of an actual flywheel, though.
Also I should confess that I have never tried to run a 914 without a prop and relied on someone else's testimony, which I can't verify right now. So maybe it can be done and maybe it can't.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=279458#279458
Attachments:
http://forums.matronics.com//files/scr=======
he Contribution link below to find out more about
lder's Bookstore www.buildersbooks.com
href="http://www.howtocrimp.com/" target="_blank">www.howtocrimp.com iption,
www.matronics.com/Navigator?RotaxEngines-List" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
ronics.com/" target="_blank">http://forums.matronics.com
==============
_blank">www.aeroelectric.com
.com" target="_blank">www.buildersbooks.com
="_blank">www.homebuilthelp.com
nk">www.howtocrimp.com
_blank">http://www.matronics.com/contribution
ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
tp://forums.matronics.com
|
|
|
|
ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
|
[b]
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rampil
Joined: 04 May 2007
Posts: 870
|
| Posted: Mon Jan 04, 2010 10:30 am Post subject: Re: Rotax 914 Won't Start |
|
|
Without a load on the crankshaft/gearbox, a Rotax 900 has several
problems, but exploding is not one of the them!
what will happen is that above 6000 engine rpm, the speed of the
hydraulic valve lifters is inadequate to completely open and close.
They essentially float out of synch and get bent out of straight by
the cams.
Apparently this situation is worsened by what is unfortunately common
occurrence: In a rush to try their new $20K investment, some builders
too busy to read the manuals try to fire up the engine not only without
the prop load, but also without the throttle cable! From the factory, the
engine is WOT without a cable pulling it back. The engine goes to above
6000 rpm in a heartbeat and no chance for the operator to react before
the engine is damaged.
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flyadive(at)gmail.com
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| Posted: Mon Jan 04, 2010 3:54 pm Post subject: Rotax 914 Won't Start |
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Rich:
OK, you have a student here ... Pull out your books and ruler and start pounding some information into my head.
Where does the 1071 come from?
How is the math done?
Barry
On Mon, Jan 4, 2010 at 12:06 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
[quote]Barry, Your mistake here is not recognizing that the 912/914 are GEARED engines. Go to all the trouble to set the prop as you like but the gearing won't bring it back around to that same point for 1071 complete combustion cycles, i.e if you set a very high idle of 2142 RPM the prop would return to your set point once a minute. Lycosaurs are great, but they have so little to do with a Rotax that experience gained with them is virtually useless.
Rick
On Mon, Jan 4, 2010 at 10:06 AM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: | Hi Rick:
HAPPY NEW YEAR!
The procedure is standard for horizontally opposed combustion engines. It is what is being used for both Continental & Lycomming engines. When having a prop balanced it is the first thing checked. I am taking a course on vibration and prop balancing and Chadwick Helmuth and ACES both cover balancing this way. This is done to reduce the amount of balance weight required. Yes, you can balance without doing a static balance but this just helps. It is like balancing tires. Ever see a car with a huge amount of weight required to balance a tire? More than likely they did not place the heavy spot of the tire across from the valve stem.
Barry
On Thu, Dec 31, 2009 at 10:12 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
| Quote: | Barry, Where did you get this procedure? It's not in any Rotax manual.
Rick Girard
On Thu, Dec 31, 2009 at 4:05 PM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: | Rich:
I asked the same question. The procedure is the same as for direct drives. Why you may ask?
Because the prop has more an effect as the FLYWHEEL having a much larger diameter than the gears.
The procedure is this:
1 - Take all safety precautions.
2 - Put the prop on with only a few bolts
3 - Remove the #1 Cyl Spark Plug.
4 - Rotate the prop so #1 piston is TDC on compression stroke.
5 - The prop #1 Blade ... Should be at the 1 O'clock position - LQQKing at it from the front of the engine.
6 - Position and reassemble as required.
Barry
On Thu, Dec 31, 2009 at 3:54 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
| Quote: |
Barry, Rotax engines run a gearbox of either 2.27 or 2.43 ratio. How exactly are you going to CLOCK it?
Rick Girard
On Thu, Dec 31, 2009 at 2:32 PM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: |
Gilles is right 100%!
You should NEVER run an engine without some form of flywheel. A prop IS a flywheel. And if your friend ran an engine without a flywheel and is alive to talk about it he is either lucky or a liar.
An engine run without a flywheel or the proper size flywheel can JUMP into a RUNAWAY condition and reach RPM's so high the engine will literally tear itself apart / explode.
Another question to throw into the pot: Is the prop properly CLOCKED? If it is not in the correct position you will get rough running and vibration.
Barry
On Thu, Dec 31, 2009 at 2:51 PM, AmphibFlyer <SeaRey(at)abstractconcreteworks.com (SeaRey(at)abstractconcreteworks.com)> wrote:
| Quote: | --> RotaxEngines-List message posted by: "AmphibFlyer" <SeaRey(at)AbstractConcreteWorks.com>
Gilles.Thesee(at)ac-greno wrote:
| Quote: | Rotax engines have NO flywheel... Running a Rotax without a prop is a no-no.
|
Well, you're right, mostly. I shouldn't have said that they do. On the other hand, the Heavy Maintenance Manual discusses "flywheel hub" in several places (July 01/2008, 74-00-00, page 49, page 117, and page 25). It doesn't seem to show a clear diagram of an actual flywheel, though.
Also I should confess that I have never tried to run a 914 without a prop and relied on someone else's testimony, which I can't verify right now. So maybe it can be done and maybe it can't.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=279458#279458
Attachments:
http://forums.matronics.com//files/scr=======
he Contribution link below to find out more about
lder's Bookstore www.buildersbooks.com
href="http://www.howtocrimp.com/" target="_blank">www.howtocrimp.com iption,
www.matronics.com/Navigator?RotaxEngines-List" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
ronics.com/" target="_blank">http://forums.matronics.com
==============
_blank">www.aeroelectric.com
.com" target="_blank">www.buildersbooks.com
="_blank">www.homebuilthelp.com
nk">www.howtocrimp.com
_blank">http://www.matronics.com/contribution
ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
tp://forums.matronics.com
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ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
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grahamsingleton(at)btinte
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| Posted: Mon Jan 04, 2010 5:27 pm Post subject: Rotax 914 Won't Start |
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It is pointless "clocking" the prop on a Rotax because the prop will
reclock itself continuously as the gearbox steadily alters the relation
between prop and crank.
Graham
On 04/01/2010 16:06, FLYaDIVE wrote:
| Quote: | Hi Rick:
HAPPY NEW YEAR!
The procedure is standard for horizontally opposed combustion
engines. It is what is being used for both Continental & Lycomming
engines. When having a prop balanced it is the first thing checked.
I am taking a course on vibration and prop balancing and Chadwick
Helmuth and ACES both cover balancing this way. This is done to
reduce the amount of balance weight required. Yes, you can balance
without doing a static balance but this just helps. It is like
balancing tires. Ever see a car with a huge amount of weight
required to balance a tire? More than likely they did not place the
heavy spot of the tire across from the valve stem.
Barry
|
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Mon Jan 04, 2010 6:45 pm Post subject: Rotax 914 Won't Start |
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The crank on the 2.43 ratio gearbox has a 21 tooth gear on the crankshaft and a 51 tooth on the prop shaft. When the crank turns through on complete combustion cycle the 51 tooth gear advances only 42 teeth, roughly 60 degrees less than a full revolution. If you want to look at it in terms of revolutions, for each combustion cycle the crank gear goes around 2 times and the prop shaft gear goes around .82353 times.
It was here that Rick went off the rails. The only way I could get back on track was to do it the bonehead way and make a spreadsheet. It turns out that when the crank goes through 17 combustion cycles (34 revolutions of the crank, or 714 teeth) the prop shaft gear has gone around 14 times (714 teeth) at which time the number 1 tooth on booth gears would again be aligned.
So, sorry for the original miscalculation, the concept was correct but the math was faulty.
Rick
On Mon, Jan 4, 2010 at 5:19 PM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
[quote]Rich:
OK, you have a student here ... Pull out your books and ruler and start pounding some information into my head.
Where does the 1071 come from?
How is the math done?
Barry
On Mon, Jan 4, 2010 at 12:06 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
| Quote: |
Barry, Your mistake here is not recognizing that the 912/914 are GEARED engines. Go to all the trouble to set the prop as you like but the gearing won't bring it back around to that same point for 1071 complete combustion cycles, i.e if you set a very high idle of 2142 RPM the prop would return to your set point once a minute. Lycosaurs are great, but they have so little to do with a Rotax that experience gained with them is virtually useless.
Rick
On Mon, Jan 4, 2010 at 10:06 AM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: |
Hi Rick:
HAPPY NEW YEAR!
The procedure is standard for horizontally opposed combustion engines. It is what is being used for both Continental & Lycomming engines. When having a prop balanced it is the first thing checked. I am taking a course on vibration and prop balancing and Chadwick Helmuth and ACES both cover balancing this way. This is done to reduce the amount of balance weight required. Yes, you can balance without doing a static balance but this just helps. It is like balancing tires. Ever see a car with a huge amount of weight required to balance a tire? More than likely they did not place the heavy spot of the tire across from the valve stem.
Barry
On Thu, Dec 31, 2009 at 10:12 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
| Quote: | Barry, Where did you get this procedure? It's not in any Rotax manual.
Rick Girard
On Thu, Dec 31, 2009 at 4:05 PM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: | Rich:
I asked the same question. The procedure is the same as for direct drives. Why you may ask?
Because the prop has more an effect as the FLYWHEEL having a much larger diameter than the gears.
The procedure is this:
1 - Take all safety precautions.
2 - Put the prop on with only a few bolts
3 - Remove the #1 Cyl Spark Plug.
4 - Rotate the prop so #1 piston is TDC on compression stroke.
5 - The prop #1 Blade ... Should be at the 1 O'clock position - LQQKing at it from the front of the engine.
6 - Position and reassemble as required.
Barry
On Thu, Dec 31, 2009 at 3:54 PM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
| Quote: |
Barry, Rotax engines run a gearbox of either 2.27 or 2.43 ratio. How exactly are you going to CLOCK it?
Rick Girard
On Thu, Dec 31, 2009 at 2:32 PM, FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)> wrote:
| Quote: |
Gilles is right 100%!
You should NEVER run an engine without some form of flywheel. A prop IS a flywheel. And if your friend ran an engine without a flywheel and is alive to talk about it he is either lucky or a liar.
An engine run without a flywheel or the proper size flywheel can JUMP into a RUNAWAY condition and reach RPM's so high the engine will literally tear itself apart / explode.
Another question to throw into the pot: Is the prop properly CLOCKED? If it is not in the correct position you will get rough running and vibration.
Barry
On Thu, Dec 31, 2009 at 2:51 PM, AmphibFlyer <SeaRey(at)abstractconcreteworks.com (SeaRey(at)abstractconcreteworks.com)> wrote:
| Quote: | --> RotaxEngines-List message posted by: "AmphibFlyer" <SeaRey(at)AbstractConcreteWorks.com>
Gilles.Thesee(at)ac-greno wrote:
| Quote: | Rotax engines have NO flywheel... Running a Rotax without a prop is a no-no.
|
Well, you're right, mostly. I shouldn't have said that they do. On the other hand, the Heavy Maintenance Manual discusses "flywheel hub" in several places (July 01/2008, 74-00-00, page 49, page 117, and page 25). It doesn't seem to show a clear diagram of an actual flywheel, though.
Also I should confess that I have never tried to run a 914 without a prop and relied on someone else's testimony, which I can't verify right now. So maybe it can be done and maybe it can't.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=279458#279458
Attachments:
http://forums.matronics.com//files/scr=======
he Contribution link below to find out more about
lder's Bookstore www.buildersbooks.com
href="http://www.howtocrimp.com/" target="_blank">www.howtocrimp.com iption,
www.matronics.com/Navigator?RotaxEngines-List" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
ronics.com/" target="_blank">http://forums.matronics.com
==============
_blank">www.aeroelectric.com
.com" target="_blank">www.buildersbooks.com
="_blank">www.homebuilthelp.com
nk">www.howtocrimp.com
_blank">http://www.matronics.com/contribution
ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
tp://forums.matronics.com
|
|
|
|
ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
|
ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
ttp://forums.matronics.com
===========
_blank">http://www.matronics.com/contribution
|
ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
|
[b]
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http://www.matronics.com/Navigator?RotaxEngines-List |
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