Today's Message Index:
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1. 04:09 AM - Re: Re: WRT M3X prop boom measurements. (Brad Stump)
2. 08:13 AM - Re: WRT M3X prop boom measurements. (JetPilot)
3. 08:34 AM - Re: WRT M3X prop boom measurements. (lucien)
4. 09:57 AM - Re: Re: WRT M3X prop boom measurements. (b young)
5. 10:19 AM - blog? (Larry Cottrell)
6. 12:25 PM - Re: Re: WRT M3X prop boom measurements. (John Hauck)
7. 12:38 PM - Re: Re: WRT M3X prop boom measurements. (John Hauck)
8. 01:14 PM - Re: WRT M3X prop boom measurements. (lucien)
9. 01:33 PM - Re: Re: WRT M3X prop boom measurements. (John Hauck)
10. 02:19 PM - Re: WRT M3X prop boom measurements. (lucien)
11. 02:36 PM - Re: Re: WRT M3X prop boom measurements. (John Hauck)
12. 03:04 PM - Re: WRT M3X prop boom measurements. (lucien)
13. 03:34 PM - Re: Re: WRT M3X prop boom measurements. (zeprep251@aol.com)
14. 03:49 PM - Rotax Operating Parameters (John Hauck)
15. 03:49 PM - Re: WRT M3X prop boom measurements. (lucien)
16. 05:39 PM - Re: Rotax Operating Parameters (lucien)
17. 05:49 PM - Re: Re: WRT M3X prop boom measurements. (Ron @ KFHU)
18. 06:21 PM - Re: Re: Rotax Operating Parameters (John Hauck)
19. 06:48 PM - Re: Re: WRT M3X prop boom measurements. (Jack B. Hart)
20. 08:05 PM - Re: Re: WRT M3X prop boom measurements. (Ron @ KFHU)
21. 09:07 PM - Re: Rotax Operating Parameters (lucien)
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Subject: | Re: WRT M3X prop boom measurements. |
Boyd,
Thank you and others who have offered advice.Iam going to increase the pitch this
week-end and see if this will make go faster.
> -----Original Message-----
> From: by0ung@brigham.net
> Sent: Wed, 3 Jun 2009 09:50:16 -0600
> To: kolb-list@matronics.com
> Subject: RE: Kolb-List: Re: WRT M3X prop boom measurements.
>
>
>> Hi Russ,
>> I hope i'am not asking a dumb question here,but I need some
>> advice.My engine's peak Hp is at 6500 rpm,I climb out at 700-800
>> fpm,and cruse at 65-70 mph.If I increase the pitch of my 3-blade
>> prop, will I increase my cruse or climb rate?
>
>>>>>>>>>>>>>>>>
>
> Brad
>
> Lets think out loud here.
>
> With a plane with a constant speed prop they always set to a fine pitch
> for
> takeoff allowing max rpm. This equals max take off performance, climb
> rate.
>
> When the same plane gets up to speed they increase the pitch, reducing
> the
> rpm. This gives them a little faster cruse. It allows the prop to use
> up
> the HP with out over reving.
>
> This becomes a larger factor when the aircraft speed is above 130 - 150
> or
> so.
>
> In your case, if you climb at 6500 at wot,,, then at straight and level
> you
> will be over reving. So you have to pull the power back. If you
> increase
> the pitch you will climb at (lets say for example) 6250 rpm.. at that
> rpm
> your engine is not putting out the full rated hp.(slower climb) But in
> straight and level flight you will pull 6500 and put the full hp to the
> prop. Thus going faster, because you have not had to pull the power back.
>
> Boyd Young
>
>
>
>
>
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Subject: | Re: WRT M3X prop boom measurements. |
Prop pitch will have a huge effect on your cruise and top speed. I have done
a lot of experimenting with it on my MK III Xtra with the 912-S and 3 blade Warp
Drive prop.
When I pitched for 5800 RPM climb, which is the maximum RPM for the Rotax 912-S,
I get the best acceleration and climb, but cruise speed is horrible. It takes
a lot more RPM, power, and fuel to cruise at 75 MPH. All my high end speeds
were way down, top level flight speed is limited by RPM. If all one ever did
was climb, the low pitch / high RPM setting might be ok, but for overall flying,
it really sucks :(
With the prop set for 5200 RPM climb, I give up a couple hundred feet per minute
in climb, but 75 MPH cruise is achieved at a much lower RPM, and power setting
with significantly lower fuel usage, and top level flight speed is much better.
The cruise with lots of pitch in the prop is so much improved, I will
gladly give up a couple hundred RPM in climb. The added advantage is that not
running the engine to its absolute maximum RPM should increase its life.
The Rotax 912-S is designed to run at high RPM's, but the 5500 - 5800 RPM range
is time limited by Rotax for a reason, and it will probably increase the engines
life keep it at 5500 RPM and below and just not to try to get every last
HP out of it.
Mike
--------
"NO FEAR" - If you have no fear you did not go as fast as you could
have !!!
Kolb MK-III Xtra, 912-S
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Subject: | Re: WRT M3X prop boom measurements. |
JetPilot wrote:
> Prop pitch will have a huge effect on your cruise and top speed. I have done
a lot of experimenting with it on my MK III Xtra with the 912-S and 3 blade
Warp Drive prop.
>
> When I pitched for 5800 RPM climb, which is the maximum RPM for the Rotax 912-S,
I get the best acceleration and climb, but cruise speed is horrible. It takes
a lot more RPM, power, and fuel to cruise at 75 MPH. All my high end speeds
were way down, top level flight speed is limited by RPM. If all one ever
did was climb, the low pitch / high RPM setting might be ok, but for overall flying,
it really sucks :(
>
> With the prop set for 5200 RPM climb, I give up a couple hundred feet per minute
in climb, but 75 MPH cruise is achieved at a much lower RPM, and power setting
with significantly lower fuel usage, and top level flight speed is much
better. The cruise with lots of pitch in the prop is so much improved, I will
gladly give up a couple hundred RPM in climb. The added advantage is that
not running the engine to its absolute maximum RPM should increase its life.
The Rotax 912-S is designed to run at high RPM's, but the 5500 - 5800 RPM range
is time limited by Rotax for a reason, and it will probably increase the engines
life keep it at 5500 RPM and below and just not to try to get every last
HP out of it.
>
> Mike
BTW, this is also true of the 2-strokes but a bit higher degree than the 912. It's
a common misconception that they last longer running at 6000+ rpm continuously.
Actually, the "sweet spot" for continuous operation with them is in the
5200 to 5500 range, at somewhere in the neighborhood of 2/3 throttle.
Also, they can't run at full throttle on a continuous basis. The TBO goes down
significantly when they're run wide open all the time regardless of the rpm and
something will eventually give (usually the con rod big end is the first to
go). Especially the 582, tho the 503 and 447 can take that for a while longer.
The 912 is sturdier in that regard as they can run WOT continuously below 5500
rpm (IIRC from the operator's manual).
The sweet spot on my 912ULS seems to be around 5050 rpm....
LS
--------
LS
Titan II SS
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Subject: | Re: WRT M3X prop boom measurements. |
Boyd,
Thank you and others who have offered advice.Iam going to increase the pitch
this week-end and see if this will make go faster.
>>>>>>>>>>>>>>>>>>>>.
My thoughts were placed out there for theory. Remember I have never run a
two stroke. And I don't know what the changes will do to the engine /
jetting / temps / etc.
You mentioned that you were going to pull it back and run at 5300 rpm....
also know that in a go fast design with constant speed prop, they set the
power level by using the manifold pressure gauge.. assuming that you run
at 5300 before and you increase the pitch and run again at 5300,,, it will
require a bit more throttle ( increased manifold pressure ) to compensate
for the additional prop load.. it theory you should go faster and also
have a greater fuel burn per hour, but the fuel burn per mile may go down.
As you go faster there is also an increase in drag... hard to know what the
trade off's will be.
If you make a good discovery, let us know.
Boyd Young
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I have put up a blog about the Owyhee area, and the things that I do and
see here. I just finished a post about the little fly-in that we hosted
here after the MV trip. The pictures enlarge if clicked on. You are
welcome to "follow" or just visit occasionally. No kids, just flying and
fishing pictures with an occasional funny ( to me) story.
http://owyheeflyer.blogspot.com/
Larry C
Firestar II 480 hours
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Subject: | Re: WRT M3X prop boom measurements. |
The Rotax 912-S is designed to run at high RPM's, but the 5500 - 5800 RPM
range is time limited by Rotax for a reason, and it will probably increase
the engines life keep it at 5500 RPM and below and just not to try to get
every last HP out of it.
>
> Mike
The 912 series engines are designed to operate up to 5800 rpm for 5 minutes
max.
5500 max contiuous.
To get the best overall performance with a fixed pitch prop (ground
adjustable), prop it like you would a boat: WOT, straight and level flight,
just bump the red line - 5500 rpm.
75% power is about 5,000 rpm.
john h
mkIII
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Subject: | Re: WRT M3X prop boom measurements. |
> BTW, this is also true of the 2-strokes but a bit higher degree than the
912. It's a common misconception that they last longer running at 6000+ rpm
continuously. Actually, the "sweet spot" for continuous operation with them
is in the 5200 to 5500 range, at somewhere in the neighborhood of 2/3
throttle.
>
> LS
Max rpm for Rotax two strokes is 6800 rpm for 5 minutes.
Max contiuous is 6500 rpm.
5800 rpm is 75% power, the optimum rpm to operate a Rotax two stroke
continuously.
5200 to 5500 rpm is the area the engine is trying to get "on the pipe", not
the sweet spot for me. The older two strokes were very unhappy in this rpm
range. They would either speed up or fall off. The engine is not
developing full efficiency below 5500 rpm.
Power settings are easier to describe using rpm rather than throttle
settings.
john h
mkIII
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Subject: | Re: WRT M3X prop boom measurements. |
John Hauck wrote:
>
>
> Max rpm for Rotax two strokes is 6800 rpm for 5 minutes.
>
> Max contiuous is 6500 rpm.
>
> 5800 rpm is 75% power, the optimum rpm to operate a Rotax two stroke
> continuously.
>
> 5200 to 5500 rpm is the area the engine is trying to get "on the pipe", not
> the sweet spot for me. The older two strokes were very unhappy in this rpm
> range. They would either speed up or fall off. The engine is not
> developing full efficiency below 5500 rpm.
>
> Power settings are easier to describe using rpm rather than throttle
> settings.
>
> john h
> mkIII
The 503 can handle 5800, but the TBO does come out a bit higher when it's kept
in the region of 5400 or thereabouts.
Putting it another way, if 5400 continuous isn't enough to fly the plane as needed,
it's probably underpowered.
5800 was high on my FSII, regardless of throttle setting (as it varied depending
on my pitch setting) it also put the gas consumption above 3 gph without really
substantially increasing my cruise speed.
5300 was spot on comfortable for the engine with no wandering rpm or sensitivity
in the throttle setting that I ever noticed on any plane I've used the 503 on.
With my FS II, gas consumption ran about 2.8 gph and I got about 65mph cruise
at that RPM.
There was never a better match made between plane and engine than the FSII and
503.
LS
--------
LS
Titan II SS
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Subject: | Re: WRT M3X prop boom measurements. |
> The 503 can handle 5800, but the TBO does come out a bit higher when it's
kept in the region of 5400 or thereabouts.
>
> LS
A 503 can operate continuously at 6500 rpm.
Optimum performance is 75% power, 5800 rpm.
TBO is established by the manufacturer who does not specify a particular rpm
other than 6500 max continuous.
Where do you get your info reference extended TBO if you operate "in the
region of 5400 or thereabouts"?
I don't pay much attention to TBO on two or four stroke engines established
by manufacturers. There is no guarantee the engines will go that long.
Most will go well beyond manufacturers "suggested" TBO before performance
degradation or failure.
john h
mkIII
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Subject: | Re: WRT M3X prop boom measurements. |
John Hauck wrote:
>
>
> A 503 can operate continuously at 6500 rpm.
>
Don't mean to be contrary, but no it cannot. The chances of failure go WAY up if
it's run at 6500 rpm all the time. Sometimes they make the specified 300 hour
TBO run this hard, but failures are far more frequent (siezures and con rod
failures are the most usual ones).
>
> Optimum performance is 75% power, 5800 rpm.
>
> TBO is established by the manufacturer who does not specify a particular rpm
> other than 6500 max continuous.
>
> Where do you get your info reference extended TBO if you operate "in the
> region of 5400 or thereabouts"?
>
Decades of field experience in a variety of planes by a very wide variety of pilots.
I have about a decade under/in front of the 503 myself.
What we know from that is that when run in the region of 5200 to 5500 continuous,
the 503 generally goes for about 450 to 500 hours (the original motor on my
FS II had about 450 hours or so on it when I replaced it, it was still running
fine at the time). The 447 commonly goes even longer than that. The 582 is the
only weak one and that's in the area of the crankshaft. But even it commonly
still has good compressions after over 400 hours of use
503's run at 6500 continuous may hit the factory 300 hour TBO but the failure rate
is somewhat higher. drop 1000rpm off that cruise figure and 300 hours is cake.
>
> I don't pay much attention to TBO on two or four stroke engines established
> by manufacturers. There is no guarantee the engines will go that long.
> Most will go well beyond manufacturers "suggested" TBO before performance
> degradation or failure.
>
> john h
> mkIII
I tend to go with field experience myself, especially when there's a lot of data
like there is with the 503.
LS
--------
LS
Titan II SS
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Subject: | Re: WRT M3X prop boom measurements. |
> Decades of field experience in a variety of planes by a very wide variety
of pilots. I have about a decade under/in front of the 503 myself.
>>
10 years is a long time. How does that equate to flight hours?
john h
mkIII
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Subject: | Re: WRT M3X prop boom measurements. |
John Hauck wrote:
> > Decades of field experience in a variety of planes by a very wide variety
> of pilots. I have about a decade under/in front of the 503 myself.
> >>
>
>
> 10 years is a long time. How does that equate to flight hours?
>
> john h
> mkIII
I stopped counting at about 500, but there's some unaccounted-for trike hours and
my 100 hours in my FSII since then.
Definitely enough to learn what a fine motor it is... I still have my toolset and
a spare gasket set.....
LS
--------
LS
Titan II SS
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Subject: | Re: WRT M3X prop boom measurements. |
Don't you believe manifold pressure or throttle position should also be a factor
in determining % of power calculations? At full throttle my 503 pulled 2 inches
of cable out of the housing and turned 6200 on climb out.But at cruise at
5500 it only pulled 7/8 of an inch of cable out of the housing.With no prop on
it,it probably would turn 7000 slightly off idle but it would not be a good
measure of power production.5800 could be 75% of allowable rpm but not power production
it would seem to me.
? Just wondering,G Aman
-----Original Message-----
From: John Hauck <jhauck@elmore.rr.com>
Sent: Thu, 4 Jun 2009 3:37 pm
Subject: Re: Kolb-List: Re: WRT M3X prop boom measurements.
?
> BTW, this is also true of the 2-strokes but a bit higher degree than the
912. It's a common misconception that they last longer running at 6000+ rpm
continuously. Actually, the "sweet spot" for continuous operation with them
is in the 5200 to 5500 range, at somewhere in the neighborhood of 2/3
throttle.?
>?
> LS?
?
Max rpm for Rotax two strokes is 6800 rpm for 5 minutes.?
?
Max contiuous is 6500 rpm.?
?
5800 rpm is 75% power, the optimum rpm to operate a Rotax two stroke
continuously.?
?
5200 to 5500 rpm is the area the engine is trying to get "on the pipe", not
the sweet spot for me. The older two strokes were very unhappy in this rpm
range. They would either speed up or fall off. The engine is not
developing full efficiency below 5500 rpm.?
?
Power settings are easier to describe using rpm rather than throttle
settings.?
?
john h?
mkIII ?
?
?
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Subject: | Rotax Operating Parameters |
If the engine is propped correctly, 5800 rpm in cruise is 75% power.
Don't believe the engines are intended to be operated without a prop.
john h
mkIII
Don't you believe manifold pressure or throttle position should also
be a factor in determining % of power calculations? At full throttle my
503 pulled 2 inches of cable out of the housing and turned 6200 on climb
out.But at cruise at 5500 it only pulled 7/8 of an inch of cable out of
the housing.With no prop on it,it probably would turn 7000 slightly off
idle but it would not be a good measure of power production.5800 could
be 75% of allowable rpm but not power production it would seem to me.
Just wondering,G Aman
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Subject: | Re: WRT M3X prop boom measurements. |
zeprep251(at)aol.com wrote:
> Don't you believe manifold pressure or throttle position should also be a factor
in determining % of power calculations? At full throttle my 503 pulled 2 inches
of cable out of the housing and turned 6200 on climb out.But at cruise at
5500 it only pulled 7/8 of an inch of cable out of the housing.With no prop
on it,it probably would turn 7000 slightly off idle but it would not be a good
measure of power production.5800 could be 75% of allowable rpm but not power
production it would seem to me.
> Just wondering,G Aman
>
> --
Don't know about anyone else, but I do.....
OTOH, it's hard to tell w/o a manifold pressure gauge which most 503 equipped planes
don't have. There you have to approximate the power level based on the load
and rpm, etc. So it's reasonable to guess that at a certain rpm you're running
such-and-such throttle.
The torque/power graphs for the rotaxen are all done at WOT I believe, so those
are max figures possible for each of those rpms. If you're turning those rpm's
at more closed throttle settings, or flying at higher altitudes, the power output
will be less than that stated on the graph.
Where I live, 3/4 throttle is all you can do unless you have a turbo or supercharger
fitted......
LS
--------
LS
Titan II SS
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Subject: | Re: Rotax Operating Parameters |
John Hauck wrote:
> If the engine is propped correctly, 5800 rpm in cruise is 75% power.
>
> Don't believe the engines are intended to be operated without a prop.
>
> john h
> mkIII
>
Ah, thanks for starting a new thead on this.
So if I may ask again, how many hours do you have on the 503 at 6500 continuous
rpm? How many motors did you run to TBO at that setting? How many did you run
past TBO?
I'd also be interested in your operating parameters - CHT and EGT readings in particular.
Thanks,
LS
--------
LS
Titan II SS
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From: | "Ron @ KFHU" <captainron1@cox.net> |
Subject: | Re: WRT M3X prop boom measurements. |
There is no adventage at all to a single nlade prop. The parasitic drag and for
that matter the induced drag will be the same. If all the props were designed
for optimal effiecncey their total surface area would be almost identical, with
probably the single blade prop having a bit more crosse sectional plane, and
more parasitic drag as it has to be heavier to handle the root load on the single
blade.. In other words to use up 100 HP all the props by deffinition will
have pretty much the same total airfoil surface area and the same induced drag
curve.
The problem with the single blade prop using 100 hp will be a tremendous wieght
disadventage to boot. so not only it will have the same parasitic ( or more )
drag but also the same induced drag and then it will weigh X times more (lets
start with a counter weight that does nothing, then add to that a very thick
crank to stop the bending moment on the crank, overbuilt engine mounts and frame,
not to mention a very likely resonance that will be impossible to stop as
the airframe has to deal with that big asymmetrical load frequency. Look we have
two legs, not one. A kangaroo has two hind legs not one. Dogs run faster because
they have four legs. Birds have two wings not one, dragon fly has 4 wings
not one. If there is a case where one propelling surface with his inherent imbalance
was better some creature somewhere would have taken advantage of it.
:-)
Sometimes I think that the original progenitor of the single blade prop was a Jokester.
================================================================================
---- Richard Girard <aslsa.rng@gmail.com> wrote:
============
http://www.ultraligero.net/Cursos/varios/helice_de_una_pala.pdf
<http://www.ultraligero.net/Cursos/varios/helice_de_una_pala.pdf>Rick
On Wed, Jun 3, 2009 at 6:35 PM, b young <by0ung@brigham.net> wrote:
>
>
> For aircraft like ours, I agree that there wouldn't be much if any
> measurable advantage to a one blade prop, and the associated problems would
> outweigh any slight advantages. However, they have been used to advantage
> on some model airplanes... control line "speed" ships that can do 200mph,
> with engines turning around 30,000 rpm. With such tiny props turning so
> fast, the blades ARE close enough together that going to one blade helps.
>
> -Dana
> >>>>>>>>>>>>>>>>>>.
>
> Dana
>
> For a 1 blade to do its job effectively I would think that it should be
> installed on a slick go fast plane. The cruise would be in keeping with
> the
> large pitch angle needed to use up the HP. And less of the HP being used up
> as parasitic drag. To put it on a slow aircraft the prop would use up the
> hp but be stalled, therefore not creating the thrust that it could do on a
> faster craft.
>
> And as for the 1 blade design being the most efficient,, I should have
> clarified it by saying in cruise, and in a tractor configuration, where it
> is not slapping the large pitch against the disturbed air,, climb would
> probably not be as good even with the pitch reducing coning angle.
>
> Boyd Young
>
>
--
kugelair.com
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Subject: | Re: Rotax Operating Parameters |
> So if I may ask again, how many hours do you have on the 503 at 6500
continuous rpm? How many motors did you run to TBO at that setting? How many
did you run past TBO?
> I'd also be interested in your operating parameters - CHT and EGT readings
> in particular.
>
> Thanks,
> LS
Had a Cuyuna ULIIO2 on my Ultrastar. It had 385.0 hours on it when I tossed
the parachute and totaled the airplane. This engine developed 75% power at
5800 rpm. 5800 rpm was my cruise power setting. I can not remember what
max continuous rpm was. Been 24 years since I flew that airplane. No
problems with this engine. Flew that time in one year.
Had two Rotax 447 single carb engines. Kept one built on the bench so I
would not miss air shows. Flew these engines 1135 hours in my original
Firestar, in all states east of the Mississippi and a hand full west of the
Mississippi River. Cruise power was 5800 rpm. Biggest problem with these
engines was dual point ignition. Timing was critical for optimum
performance, or even mediocre performance. Soon and new points started
wearing in, timing changed. On a typical 3 to 4 week cross country flight
the points rubbing blocks would wear enough to cause engine problems. Many
engines in the old days were seized and ruined because of point ign. Coils,
hard mounted on the blower housing would wear so badly from vibration, the
coil windings would break loose inside the steel frame. Another weakness
was caged wrist pin bearings which failed and destroyed an entire engine.
Never had a big end bearing or crank be aring fail. I don't know how many
hours each engine had individually. Parts and components were swapped when
necessary to keep me flying. One of those engines came from Disney World
when they had a flight demo team in Orlando. BTW, I put that time on the FS
in less than 3 years.
I never had a CHT problem and can not remember what temps I operated at.
CHT was run 1150 to 1200F cruise and about 1050 full throttle.
You asked how many hours I have on a 503 at 6500 rpm. Have no idea.
Probably not many. My 503 experience is flying factory aircraft equipped
with that engine, usually at Sun and Fun and Oshkosh. Normally, not much
chance to pull 6500 rpm in that environment, but the factory always pitches
engines light for the two big air shows. Makes for impressive take off and
climb rates. Probably pulled well over 6500 every take off and down wind if
there wasn't someone in my way. ;-)
I didn't fly my two strokes WOT on cross countries because of their
vulnerabilities and the fact I was breaking new ground by traveling many
miles from home. Normal cruise was 5800.
912 is a different animal. WOT for several hours climbing over the Rockies
is not uncommon. 5000 is normal cruise, for me, but 5200 and 5400 if I need
it.
I believe two and four stroke engines today need to be run, not babied. I
flew 60.2 hours in less than 18 days. The last two days on my return
flight, about 15 hours, were turned at 5200. Normally, my cruise speed
increases as I get nearer to home base. ;-)
john h
mkIII
Message 19
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Subject: | Re: WRT M3X prop boom measurements. |
At 08:49 PM 6/4/09 -0400, you wrote:
>
>
................
If there is a case where one propelling surface with his inherent imbalance was
better some creature somewhere would have taken advantage of it. :-)
>Sometimes I think that the original progenitor of the single blade prop was a
Jokester.
>
May be a fish?
Jack B. Hart FF004
Winchester, IN
Message 20
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From: | "Ron @ KFHU" <captainron1@cox.net> |
Subject: | Re: WRT M3X prop boom measurements. |
Yeah thought about that too, even a shark has two balanced fins to his tail. I
suspect Bob Young (?) could be the same troll I bounced off the flygeo list twice,
each time with a different name. :-)
======================================
---- "Jack B. Hart" <jbhart@onlyinternet.net> wrote:
============
At 08:49 PM 6/4/09 -0400, you wrote:
>
>
................
If there is a case where one propelling surface with his inherent imbalance was
better some creature somewhere would have taken advantage of it. :-)
>Sometimes I think that the original progenitor of the single blade prop was a
Jokester.
>
May be a fish?
Jack B. Hart FF004
Winchester, IN
--
kugelair.com
Message 21
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Subject: | Re: Rotax Operating Parameters |
John Hauck wrote:
>
> Had a Cuyuna ULIIO2 on my Ultrastar. It had 385.0 hours on it when I tossed
> the parachute and totaled the airplane. This engine developed 75% power at
> 5800 rpm. 5800 rpm was my cruise power setting. I can not remember what
> max continuous rpm was. Been 24 years since I flew that airplane. No
> problems with this engine. Flew that time in one year.
>
> Had two Rotax 447 single carb engines. Kept one built on the bench so I
> would not miss air shows. Flew these engines 1135 hours in my original
> Firestar, in all states east of the Mississippi and a hand full west of the
> Mississippi River. Cruise power was 5800 rpm. Biggest problem with these
> engines was dual point ignition. Timing was critical for optimum
> performance, or even mediocre performance. Soon and new points started
> wearing in, timing changed. On a typical 3 to 4 week cross country flight
> the points rubbing blocks would wear enough to cause engine problems. Many
> engines in the old days were seized and ruined because of point ign. Coils,
> hard mounted on the blower housing would wear so badly from vibration, the
> coil windings would break loose inside the steel frame. Another weakness
> was caged wrist pin bearings which failed and destroyed an entire engine.
> Never had a big end bearing or crank be aring fail. I don't know how many
> hours each engine had individually. Parts and components were swapped when
> necessary to keep me flying. One of those engines came from Disney World
> when they had a flight demo team in Orlando. BTW, I put that time on the FS
> in less than 3 years.
>
> I never had a CHT problem and can not remember what temps I operated at.
> CHT was run 1150 to 1200F cruise and about 1050 full throttle.
>
> You asked how many hours I have on a 503 at 6500 rpm. Have no idea.
> Probably not many. My 503 experience is flying factory aircraft equipped
> with that engine, usually at Sun and Fun and Oshkosh. Normally, not much
> chance to pull 6500 rpm in that environment, but the factory always pitches
> engines light for the two big air shows. Makes for impressive take off and
> climb rates. Probably pulled well over 6500 every take off and down wind if
> there wasn't someone in my way. ;-)
>
> I didn't fly my two strokes WOT on cross countries because of their
> vulnerabilities and the fact I was breaking new ground by traveling many
> miles from home. Normal cruise was 5800.
>
> 912 is a different animal. WOT for several hours climbing over the Rockies
> is not uncommon. 5000 is normal cruise, for me, but 5200 and 5400 if I need
> it.
>
> I believe two and four stroke engines today need to be run, not babied. I
> flew 60.2 hours in less than 18 days. The last two days on my return
> flight, about 15 hours, were turned at 5200. Normally, my cruise speed
> increases as I get nearer to home base. ;-)
>
> john h
> mkIII
Ok, was just wondering. After 10 years and lost-count-of hours hanging under the
503, I just found 6500 rpm continuous an extremely unusual recommendation. not
one that jives with my and many others experiences with this engine.
It's a good climbout RPM that will have no ill effects, but not on a continuous
basis....
The 2 strokes stay together just fine over the long haul, but that means running
at the 5400 watering hole rpm. 5800 the 447 and 503 can usually take ok, tho
the engine would probably be more reliable over time about 400 rpm below that
for cruise. Even more important for the 582.
WOT all the time and no I'm not surprised you had some trouble with them.
The 2-strokes can't be flown like our 912's, as you say they're very different
animals. My 912ULS just laughs when I push the go-stick forward to the stop, no
problem holding it open as needed. I do 5000 to 5100 cruise on mine and it just
hums along......
LS
--------
LS
Titan II SS
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