Hello DJA727
(XXXXX) Again i have no direct experiance with Rotax motors. I am very
in tune with motors, and especial carbs and tuning.
DJA727@aol.com wrote:
>
>
> In a message dated 2/14/2003 7:44:06 AM Pacific Standard Time,
> rparigor@suffolk.lib.ny.us writes:
>
> Well, If it's not one thing, it's something else!! Here goes my opinion on
> this:
>
> > On my speedwing monowheel, i plan on installing a 914, with CS.
> >
> > I spoke to Bill Lockwood, from Lockwood Aviation in FL for some time
> > bout the rotax motors.
> >
> > Any viabbarion kills the redrive. Unbalanced carbs, idle too slow and
> > "MOTORMOUNTS THAT ARE TOO SOFT!"
> >
>
> @@@@@@ First, I don't know what you mean by "redrive". Are you referring
> to the gear box?
(XXXXX) Yes I what refer to as redrive is the gearbox. For whatever it
is worth, the 914 has a slight different ratio compared to 912 or 912S.
also he said you can hand prop a 912 or 914, but with the higher
compression of the 912S you can not hand prop.
>
> > I am not an expert. I never saw a 914 mount in my hand.
> >
> > But Bill is suppsedlly an expert and says that 0200 mounts are a bad
> > thing.
> >
> > He said use the provided mounts, idle 1800RPM min, sync carbs exact both
> > low speed and high and have prop dynamic balanced.
> >
>
> @@@@On this subject, since the only adjustment I know of is the setting of
(XXXXX) This motor has 2 carbs. If they are not in sync on both low and
high speed it will create excessive viabrations. First you need carbs in
sync at idle. Bill says the idle stop on the Bing is not real strong so
best use lever stop as the idle stop. If you pull on stop tooo hard it
bends. Again i am only repeating what an expert has told me, i have
never seen one. So you must sync so both carbs at idle are alllowing all
cyls to fire. Then you have off the stop sync. WEhat you need to do is
disconnect the cross over tubes for this adjustment, he attaches vacume
guages to the holes for the crossover, a perfect attach point. Now you
must run motor up and make sure the vacume at each carb is the same.
this is no different than if you ever fooled with a BMW Motorcycle that
happens to have 2 Bing constant velocity carbs. If idle is adjusted
properly, does not mean off idle is adjusted properly.
Here again i have no experiance adding full power on a monowheel with
brake on, but i read somewhere that when a monowheel owner got to
something like 75 or 80% power with brake on attemptong to do a full
power ground test, it nosed over! He said he now attaches a rope to the
tailwheel and runs over it with a car tire.
> the throttle cable, I don't see where you can adjust both high and low RPM
> carb balance. I will have the prop balanced. 1800 rpm is way too high for
> landing this airplane, in my opinion.
(XXXXX) The Europa is a pretty slippery aeroplane, may be true you can
not land with 1800RPM. Going back to Mr. Lockwood who has plenty of time
repairing torn up "Gearboxes" says too slow causes viabration that tears
up the boxes. There are I am sure different types of viabrations. You
are referring to the buzzey little movements while in flight. I am sure
Mr Lockwood is referring to start up and idle/low power shake that kills
the boxes, not the low shock buzzey high RPMs. Anyway, reading bout how
things on the 0200 mount install needed to allow for more motor shake,
kinda sortta would indicate that it would stress the box more than
harder mounts.
Again i am just looking for pros and Cons, then after facts are in i can
make an educated decision.
I will try and copy and paste my EXCEL notes on another post and you can
try and wade through them.
1 thing that made me feel better, is if even on the most worn gearbox
there is, it will not let you down n flight, it can sound terrable, and
be costly to repair, but it just will begin to give you starting
problems (he said Rotax has very light flywheel and without tight
gearbox not enough mass to fire up), eventual will just not start.
If vibration is bad, the vibration is
> terrible with the stock mounts. To me, the more flexible mounts should allow
> absorbtion of energy and reduce any loads on the engine.
>
> > Here is his exact quote:
> >
> > "Motors like to be mounted fairly rigid, he is not real thrilled with
> > continental 0-200 Lord mounts if they are softer"
> >
>
> @@@@@@@@@ This doesn't make sense to me. In all engine I have worked with -
> both aircraft and auto, the goal is to relplace engine mounts when they get
> stiff with age. I can't see where a hard engine mount would help the engine.
> If this were true, why not just hard bolt the engine to the airframe! Could
> it be that these are not mounts that are sold by Rotax? Do thtey have service
> proiblems directly related to softer engine mounts? Engine mounts do not
> cause vibration - they absorb vibrational energy. Another point - these are
> aircraft engine mounts used on continental engines. What is different about a
> rotax and what is thte physical reason that softer mounts are "bad"? I am not
> a big fan of broad sweeping conclusions without supporting details.
(XXXXX) I hope I gave a bit of insite in above. i had a 1948 cessna 170
for 19 years. you replace mounts when they get stiff with large cubic
inch, high torque motors that use Applied Arciac Technology as the theme
for design.
The Rotax is alot closer to a honda Goldwing or BMW boxer than it is to
a Continental or Lycoming. It is light, much higher RPM and much lower
torque. Since HP is equal to torque times RPM (plus a fudge factor), it
matters no none not how you make a hundred HP, as far as work goes it
will do not considering other losses. You can use high RPM and low
torque or low RPM and high torque.
Now for the big Screw. propellors are much more efficient at Europa
speeds spinning large and slow as compared to spinning a smaller faster.
Going supersonic at the tips and associated noise is an issue.
So they take a high RPM low torque motor and turn it into a low RPM
high torque motor, how REDRIVE. This is not unlike how an automobile
transmission does its magic. if you have a 100HP toyota and measure the
motore direct off crank it will be 100HP. Now for this exampole i am
considering the tranny does not have any frictional lossed. In first
gear, very low RPM and very high torque or 100HP, then 4th gear which is
a 1 to 1 is same as motor, higher RPM and lower torque than first gear
but 100HP, then overdrive which is very high RPM and very low torque, or
100RPM.
The geardrive is the weak link on the Rotax, take a look at Katan fleet
service record. Out of sync carbs, idle too slow and 100LL lead getting
into and causing grief with slipper clutches, and using Castrol GTX that
is not good for gearbox at all.
The box takes a beating. You ever see a BMW boxer twin from WW2 to now
that has its motor held in place with rubber??? Out of sync it shakes
pretty good, in sync it is Much more better.
(XXXXX) I am not forming an opinion yet but gathering info, once my nose
is being rubbed into fooling real time, i will pull up Factual Database
stored between my sholders and Apply.
Next post will be what i have gathered on Rotax.
Ron Parigoris
>
> > This is per a conversation 12-30-2002.
> >
> > I am only repeating what he said.
> >
> > Any other comments to the contrary?
> >
>
> Dave
> A227
>
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