Today's Message Index:
----------------------
1. 12:07 AM - Re: 110% duty cycle? (Don Gherardini)
2. 04:47 AM - Crank failures (Ed Steuber)
3. 06:42 AM - Re: 110% duty cycle? (GeoR38@aol.com)
4. 06:52 AM - Re: Fuselage Tube Alignment (Airgriff2@aol.com)
5. 07:11 AM - Re: 110% duty cycle? (John Hauck)
6. 08:16 AM - Re: 110% duty cycle? (CaptainRon)
7. 08:30 AM - Re: 110% duty cycle? (jerb)
8. 08:40 AM - Re: 110% duty cycle? (Jack & Louise Hart)
9. 09:14 AM - Re: 110% duty cycle? (John Hauck)
10. 10:07 AM - Re: 110% duty cycle? (Jack & Louise Hart)
11. 11:21 AM - Re: 110% duty cycle? (Don Gherardini)
12. 11:28 AM - Re: 110% duty cycle? (Don Gherardini)
13. 04:26 PM - Re: 110% duty cycle? (CaptainRon)
14. 04:38 PM - duty cycle (Bob Bean)
15. 05:55 PM - Re: 110% duty cycle? (jerb)
16. 06:16 PM - Re: 110% duty cycle? (GeoR38@aol.com)
17. 06:38 PM - Re: 110% duty cycle? (John Hauck)
18. 07:01 PM - 110% duty cycle vs manifold pressure (Richard Pike)
19. 07:44 PM - Just a bit nippy... (abbygirlk9)
20. 08:02 PM - Re: 110% duty cycle? (Jeffrey Jones)
21. 08:17 PM - Re: 110% duty cycle? (John Hauck)
22. 08:22 PM - Fuselage tube / wing brace alignment (Ed Bonsell)
23. 08:24 PM - Re: 110% duty cycle? (Richard Pike)
24. 09:55 PM - Re: 110% duty cycle? (CaptainRon)
Message 1
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: "Don Gherardini" <donghe@one-eleven.net>
Richard, you are right on track pard!...at least with my treatment of my
engines...all of them, on my Garden tractor...and my 2 stroke ultralights.
Engine Longevity is exactly what at stake here, nothing else i care about.
Here are some pretty normal design parameters for IC engines in our world.
Automotive(Car)....25%to 35% duty cycle will give the manufacturer a
lifetime that will equal current warranty periods for the average target
market. Your car will run....lets say, 100 mph flat out. The engine is at
100% duty cycle if it is approaching max rpms at that speed. If you ran it
at that speed all the time, it wont last the 5 years or 50,000 miles that
the manufacturer warranties it for...not by a long way. Remember how long
that car lasted that 18 year old All- American lead footed boy? ( anybody
remember him?..hehe!)
Now that that kid is an ole fart..he easily gets over a hundred tho from his
cars because he drives them at the speed limit alot more often that not.
todays high torque lower rpm designs are operating at 10 % duty cycle in
overdrive on the highway, So thus is how the entire industry designs IC
engines, So YES, as someone said a post or 2 back, it has everything to do
with warranty. And all of Hondas best competitors design engines with the
same priorities. (If they dont we dont consider them a competitor).
back to design parameters...
Automotive..(heavy truck)....65 to 75% dutycycles
Aircraft 4 cycle gas........80 to 90 %DC...for as many hours as Man. rec.TBO
times
General purpose consumer gas (governed) 500 to 1500 hours at 80%duty cycle
Industrial Gasoline. (governed) 2500 hours at 80 to 85% DC
Industrial Diesel (governed) 3000 to 10000 at 85 to 100% DC
Consumer string trimmer( that walmart cheapie)...25 to 50 hours at 80% DC
Pro chainsaw (not the "pro" model at Walmart) 1000 hours at 100% DC
Recreational Motorcycle...25 to 35%DC
Recreational Snowmobile..25 to 35%DC
Recreational Marine........40% to 60%DC anywhere from 500 to 2500 hours
(lotsa market variations here)
Now you fellas know where most of us Kolber's fall with 2 strokes....we do
not have a single 2 cycle engine designed for us from the major
manufacturers like Rotax, Hirth, 2si ..etc... What we have are very slightly
modified recreational snowmobile ant watercraft engines to attempt to
lengthen their miserably short lives at the duty cycle we ask of them. And
this industry is struggling with that goal, as we all can easily see.
Unfortuneatly the market is so small that no major is going to consider us
for along time. Someone said that Honda is never gonna run the liability
risk....well thats only partly correct...it is always a risk VS gain factor
it.
For instance, if I come and see you Richard because you wanna use a Honda
engine on generators that you build, if we dont have one that fits your
machine just right in production, and you need a slight variation, lets say,
an airfilter on the other side...or a different crankshaft to base
height...just a modification of an exsisting model..NOT a new design
altogether...then I would need a purchase order for a minimum of 10,000
engines to get them to consider doing it for you. In the Entire ultralight
engine industry there are barely 10000 engines sold a year in the world...by
all manufacturers combined.
I dont want to get to far off track here men but here is my cyrstal ball
prediction for us all.
Then day that 2 cycle snowmibile and PWC engines are outlawed , which as
many know has already begun, with the banning in many Gov rec aeras of 2
cycles, is the last day that any of us will be able to buyb a Rotax 2 cycle
UL engine. The board of directors at Bombadier will take one look at the
small market that the airplane guys give em...and with no other market for
these babies...BOOM....production will cease. Ive been in this biz
everysince a couple a years after I graduated Spartan, with an A&P ticket
and an ASSoc. degree, when I found I needed a better living that i was gonna
get in a dieing aircraft industry, that was almost 25 years ago ,and I
wouldnt give a nickel for the chances of this not happening.
So back to you "what if"question, which you probably already have figgered
out, the engine is not gonna go to 1000 hours or whatever it was designed to
last at 30 % DC in a snowmobile....but the life will increase dramatically
with the throttle limiting the rpms when they drop below max...not the load.
The key to your question is..How much is the throttle reduced exactly...if
20 % of its throw, and the rpms stay at max for instance, then it might be
as low as 75 to 85% DC area, if the Throttle is reduced 20% and the rpms are
reduced say...by 50 or 100 rpms...this is very good....it indicates the
engines is handleing the load pretty easy.
Cooling and EGT factors come in to play to come up with a duty cycle
estimate, this can be tricky with 2 strokes, but the main thing is by
reducing the throttle then BMEP (brake mean effective pressure) is
reduced...call it cylinder/combustion pressure...and thus the engine is not
working as hard. Remember not to judge a throttle opening by the throw on
the operators end tho...slack in cables and linkages and such might change
the relationship to the actual opening....remember where this setting is and
then when you are on the ground,,,engine off...simply set the throttle there
and take a look at the opening thru the filter...or in the case of a
metering rod and butterfly...judge the lever on the butterfly and the height
of the rod.
Also , as Bill has described, unloading the engine by letting the nose down
and letting the rpms comeup at WOT is EASIER on the engine. When that prop
is pitched to limit the rpms at the recommended maximum , it is 100%
dutycycle....climbing out reduces the rpms but increases the BMEP...and
therefore increases the duty cycle above 100%. THe main misunderstanding
most people have is that pitching the prop to limit the rpms down to ..say
5500 or so at WOT is easier on the engine..it is NOT.
Don Gherardini
FireFly 098
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
--> Kolb-List message posted by: "Ed Steuber" <esteuber@rochester.rr.com>
What is the effect of a clutch betwween the prop pulses and the gearbox or cog
belt drive.....any difference?
Ed at -4 tonight in western NY
Do not archive
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: GeoR38@aol.com
In a message dated 1/25/03 11:34:52 PM Eastern Standard Time,
rwpike@charter.net writes:
>
> --> Kolb-List message posted by: Richard Pike <rwpike@charter.net>
>
> Excellent food for thought here, and I want to ask you a "What if."
>
> I have been in the habit of adjusting my prop so that I get 6500 rpm (more
> or less) at full throttle in level flight. Therefore on take off and climb
> out, I am getting about 6000-6200 rpm, or on hot summer days, about
> 5900-6000 rpm at full throttle, so that puts me within your 110% duty cycle
>
> scenario.
> "What if" you pull the throttle back a bit so that the engine drops back
> just enough rpm's to notice, say 50 or 100 rpms less, the throttle being
> retarded probably about 20% of it's throw. Is the engine now back within
> it's normal duty cycle, and the 5800 rpm load is at 80% -90% of it's duty
> cycle or some where similar? Explain this for us non professional types,
> because this could be important in terms of longevity.
> Thanks,
> Richard Pike
> MKIII N420P (420ldPoops)
>
>
> At 08:48 PM 1/25/03 -0600, you wrote:
>
> >--> Kolb-List message posted by: "Don Gherardini" <donghe@one-eleven.net>
> >
> >Mike,
> >
> >Food for thought for all.....when an engine designed to run at 6500rpms
> max
> >sustained is loaded down to ..say 5850 rpms at wide open
> >throttle(WOT)....then it is considered to be running at 110% duty cycle.
> >6500x 10%=650rpms.......6500-650=5850.....
> >Now, from my expierience in a honda industrial engine(4stroke) when you
> run
> >it under this kind of load, the 2000 hour life is cut by 50% IF you can
> keep
> >it under max temp. If you cannot....life becomes very short. Its hard for
> me
> >to understand that the same is not true for our pet 2 strokes.
> >
> >Don Gherardini
> >FireFly 098
>
Good question Mr Pike, I have a problem with the 110% duty cycle senario as
well as I KNOW that HP or power is a product of Torque times Speed times a
constant.....if the prop is pitched too high, the torque required to reach a
certain speed is too high for the engine at hand, therefore the HP is less
than 110% in my book. As a matter of fact it is less than 100% as the hi
pitched prop would not allow the engine to come up to speed due to too much
torque loading.
well......., that's the way I look at it anyway.
George Randolph
Firestar driver from Akron
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Fuselage Tube Alignment |
--> Kolb-List message posted by: Airgriff2@aol.com
Tom, Just went through all of what you are now, this past summer, helping out
a friend. According to Kolb, it is perfectly ok to elongate the fuselage
holes, (in your case),one side, 1/16" forward and 1/16" to rear on the other
side.
Fly Safe
Bob Griffin
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: John Hauck <jhauck@sw.rr.com>
> THe main misunderstanding
> most people have is that pitching the prop to limit the rpms down to ..say
> 5500 or so at WOT is easier on the engine..it is NOT.
>
> Don Gherardini
Don/Gents:
Good morning! Still cold in Alabama, but not as
cold as it has been. Only 34F at 0830.
I certainly agree with your last sentence and
always have. That is why I prop my airplanes and
my boat the same way: Pitch to bump the redline
at wide open throttle (WOT), straight and level
flight. With my ground adjustable prop I get the
best climb and cruise performance. Doesn't matter
whether it is 2 or 4 cycle engine.
Worst thing in the world for an engine is to
hammer it down, i.e., overpitch.
The above applies to gasoline as well as Diesel
engines. I used to think Diesels liked to get
lugged down until they stalled, but found out they
are just like most other engines. They have an
operational rpm they like to operate in and it is
not below their max torque producing rpm.
I personally believe the ultralight industry is
providing engines that the customer demands. They
know that the average ultralight probably never
sees more than 100 hours, some 200 hours, and a
few might make it over 300 hours. What is Rotax
TBO on their 2 cycle crank shafts? 300 hours.
Dangerous trying to think and type before I finish
my first cup of coffee. hehehe
Take care,
john h
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: CaptainRon <CaptainRon@theriver.com>
1/26/03 7:39GeoR38@aol.com
> I have a problem with the 110% duty cycle senario as
> well as I KNOW that HP or power is a product of Torque times Speed times a
> constant.....if the prop is pitched too high, the torque required to reach a
> certain speed is too high for the engine at hand, therefore the HP is less
> than 110% in my book.
===============================
I agree. I wanted to stay out of it but since you brought it up I might as
well chime in.
I think he needs to define for us his defifnition of Duty Cycle before I buy
into his analysis. If 100% of Hp is 6200 rpms, by definition anything less
than 6200 rpms at max torque is less than 100% output. If one climbs and his
engine is at 5800 rpms than he is only getting 58/62= 93% of his engin's HP.
On a 65 hp rotax that would work out to .93(65)= 60.45 of his engines
available HP. How does he get 110% duty cycle in his example does not seem
to be mathematically possible.
I think we need his definition of a Duty Cycle. So far the claim defies
logic. :-)
Message 7
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: jerb <ulflyer@airmail.net>
Don,
What is your back ground. This is the first time I've heard this 110%
thing in the years of being on several list.
I know my mode of operation is to back power down a little once I gained a
couple hundred feet but in my case I have plenty of power. I have my 447
engine propped to give me around 6000-6100 RPM on takeoff climb which turns
about 5900 on static test with tail tied down. It is the compromise
between good climb and good cruise.
jerb
At 11:32 PM 1/25/03 -0500, you wrote:
>--> Kolb-List message posted by: Richard Pike <rwpike@charter.net>
>
>Excellent food for thought here, and I want to ask you a "What if."
>
>I have been in the habit of adjusting my prop so that I get 6500 rpm (more
>or less) at full throttle in level flight. Therefore on take off and climb
>out, I am getting about 6000-6200 rpm, or on hot summer days, about
>5900-6000 rpm at full throttle, so that puts me within your 110% duty cycle
>scenario.
>"What if" you pull the throttle back a bit so that the engine drops back
>just enough rpm's to notice, say 50 or 100 rpms less, the throttle being
>retarded probably about 20% of it's throw. Is the engine now back within
>it's normal duty cycle, and the 5800 rpm load is at 80% -90% of it's duty
>cycle or some where similar? Explain this for us non professional types,
>because this could be important in terms of longevity.
>Thanks,
>Richard Pike
>MKIII N420P (420ldPoops)
>
>
>At 08:48 PM 1/25/03 -0600, you wrote:
>
> >--> Kolb-List message posted by: "Don Gherardini" <donghe@one-eleven.net>
> >
> >Mike,
> >
> >Food for thought for all.....when an engine designed to run at 6500rpms max
> >sustained is loaded down to ..say 5850 rpms at wide open
> >throttle(WOT)....then it is considered to be running at 110% duty cycle.
> >6500x 10%=650rpms.......6500-650=5850.....
> >Now, from my expierience in a honda industrial engine(4stroke) when you run
> >it under this kind of load, the 2000 hour life is cut by 50% IF you can keep
> >it under max temp. If you cannot....life becomes very short. Its hard for me
> >to understand that the same is not true for our pet 2 strokes.
> >
> >Don Gherardini
> >FireFly 098
> >
> >
>
>
>Help Stop Spam!
>Delete all address information (especially mine) off everything you
>forward, and make Blind Carbon Copy a way of life.
>Thanks! And have a blessed day.
>rp
>
>
Message 8
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: Jack & Louise Hart <jbhart@ldd.net>
Don,
A few comments interspersed below.
At 02:09 AM 1/26/03 -0600, you wrote:
>--> Kolb-List message posted by: "Don Gherardini" <donghe@one-eleven.net>
>
>Cooling and EGT factors come in to play to come up with a duty cycle
>estimate, this can be tricky with 2 strokes, but the main thing is by
>reducing the throttle then BMEP (brake mean effective pressure) is
>reduced...call it cylinder/combustion pressure...and thus the engine is not
>working as hard.
The Rotax 447 minimum throttle opening was at 40% when the engine was propped to
top out at 6,000 rpm. When the prop pitch was increased to limit the engine
to 5,600 rpm the minimum throttle position was less than 40%. So less fuel is
being burned and yes the BMEP goes down, and the engine is not working as hard.
But more importantly, bearing and ring life will be extended too. If on
assumes the BMEP are the same for both rpms, the number of bearing/crank hammering
and crank torsional impulses goes down by 400 per minute and so extends the
fatigue life of both bearings and crank. A belt reduction system also helps
to reduce engine crank torsional vibration. But the greatest improvement is
that the crank throw radial bearing load increases with the square of the rpm
decrease. See Tinkem calculation at the bottom of:
http://www.thirdshift.com/jack/firefly/victor_fuel.html
>Remember not to judge a throttle opening by the throw on
>the operators end tho...slack in cables and linkages and such might change
>the relationship to the actual opening....remember where this setting is and
>then when you are on the ground,,,engine off...simply set the throttle there
>and take a look at the opening thru the filter...or in the case of a
>metering rod and butterfly...judge the lever on the butterfly and the height
>of the rod.
I mounted a simple throttle position indicator on the FireFly so that I could determine
throttle position relative to engine speed and prop settings. What I
found was that with the Bing, the engine is operating off the idle, throttle
valve cutaway, and needle jet ranges. The engine cannot pump enough air to ever
get into the main jet region of fuel flow control. It can be seen at:
http://www.thirdshift.com/jack/firefly/firefly58b.html
>
>Also , as Bill has described, unloading the engine by letting the nose down
>and letting the rpms comeup at WOT is EASIER on the engine. When that prop
>is pitched to limit the rpms at the recommended maximum , it is 100%
>dutycycle....climbing out reduces the rpms but increases the BMEP...and
>therefore increases the duty cycle above 100%. THe main misunderstanding
>most people have is that pitching the prop to limit the rpms down to ..say
>5500 or so at WOT is easier on the engine..it is NOT.
May be the trick here is to not use WOT. Open the throttle to the minimum position
that gives max rpm and no further. In the case of the Rotax 447 that position
was no greater than 40% and with the Victor 1 the position is no greater
than 20% (uses the same Bing carburetor). If the EGTs are good at these throttle
position, there is no need to open the throttle further for engine cooling
purposes. Further enrichment (WOT) of the mixture will only be a waste of fuel
and may even reduce the BMEP. The only way the BMEP can increase is if one
can get more air/fuel mixture into the cylinder. In the case of the prop limited
engine, one can get additional fuel but not the air, so combustion becomes
less efficient, combustion temperatures and pressures fall and loads on the
bearings and crank fall.
Jack B. Hart FF004
Jackson, MO
Jack & Louise Hart
jbhart@ldd.net
Message 9
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: John Hauck <jhauck@sw.rr.com>
Good Morning Gang:
I don't know about some of you guys, but I, for
one, build and enjoy my Kolbs because they
perform. Instead of trying to detune the 447, I
was always trying to get more performance out of
it. For example, pistons/wrist pins/rings were
balanced, intake/exhaust ports were matched (Rotax
always did a poor job of matching the cylinder
liner with the aluminum cylinder), and prop pitch
set for optimum performance. To me, the awesome
performance of a little Ultrastar and Firestar fed
my adrenaline starved body.
To detune for minimum performance and fly around
the patch would get mighty boring really quick.
However, different strokes for different folks.
I am trying to understand how loading down a prop
with pitch is going to lighten the load and
increase bearing and engine life. I equate that
to driving around in 5th gear at 25 mph and
expecting the auto or truck engine to last
longer. Don't think that will happen, but I am
not an engineer, only a user.
Think I will treat my engines the same as I always
have. Let them turn, breath and perform like they
were designed to. Keep'em below red line and
let'em live.
Not hard to visualize airplanes and pilots getting
into trouble by detuning with excessive prop
pitch. What are you going to do when you need all
that 40 hp from the old 447, but you have gotten
it all tied up with an over abundance of prop
pitch? I want all the power I can get when I need
it. Power hungry. :-)
One of the sorriest feelings in the world, to me,
is to underestimate the amount of pitch dialed
into a new prop setting. Once airborne the rpm's
are 2, 3, 4 hundred rpm less than normal (for
me). Can not wait to get around the patch, get on
the ground, and take some of that pitch out to
free up the engine and let it live.
Take care,
john h
DO NOT ARCHIVE
Message 10
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: Jack & Louise Hart <jbhart@ldd.net>
John,
At 11:13 AM 1/26/03 -0600, you wrote:
>--> Kolb-List message posted by: John Hauck <jhauck@sw.rr.com>
>
>To detune for minimum performance and fly around
>the patch would get mighty boring really quick.
>However, different strokes for different folks.
>
>I am trying to understand how loading down a prop
>with pitch is going to lighten the load and
>increase bearing and engine life. I equate that
>to driving around in 5th gear at 25 mph and
>expecting the auto or truck engine to last
>longer. Don't think that will happen, but I am
>not an engineer, only a user.
John,
If we had light weight, inexpensive, in flight adjustable props we could have the
best of both worlds. But one has to choose between climb, cruise or a combination
some where between the two. Running flat pitch to run the engine against
the red line gives a good climb rate and a poorer cruise than a prop running
with more pitch. Running with a flat pitch prop means that you have to turn
a higher number of total engine revs to get from point A to point B, when you
could get there in the same time using fewer total revs with a higher pitch prop
and less horsepower, improved fuel economy and less wear and tear.
The automobile analogy would be the comparison between tuning for the drag strip
or street performance. Or driving a car with overdrive disabled, etc. There
is no doubt an engine will last longer the more conservatively it is used.
High rpms use up engines quicker, and in aircraft they don't necessarily get you
from point A to point B any quicker.
Jack B. Hart FF004
Jackson, MO
Do not archive
Jack & Louise Hart
jbhart@ldd.net
Message 11
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: "Don Gherardini" <donghe@one-eleven.net>
George, and Capt Ron,
The term Duty Cycle as designated as a % Has nothing to do with % of max
Horsepower men. It is used as an indicator as to how long an engine(or
component) will last at the work (duty) being preformed.
The factors in rating duty cycle are several.
For instance how long a connecting rod will last with(how many cycles) lets
just use this example so this post wont be so long.
Q. At what rpm is the maximum pressure applied to the rod?
A. At the rpm where the highest Volumetric effiency occurs.
Q. How can we find this rpms level?
A. It will be the level of peak torque on the curve. Here the BMEP will be
the highest, and VE( volumetric effeicency) is highest, and likely is not at
max rated rpm.
Q.why is the horspower peak not at this point?
A. because Torque is a measured unit and HP is calculated (not measured)
with a time factor added .(and the HP formula sometimes subject to marketing
influeces not relating to engineering values!, particularly in todays
market) Not All manufacturers use Watts hp formula anymore....dont get me
started down that road....
OK...we have established that the most force will be applied to the rod when
the cylinder pressure is the highest...thays is pretty straight forward.
now...how long do we WANT it to last? Herein is the Term Duty cycle's reason
for being. So an engineer on a design Team can decide on just how strong of
a rod to make and just how good of a bearing to request from his vendor. The
market will require the Duty Cycle or the product will not be saleable.
Now, as we all understand he engine being an air pump...and lets just pull a
number out of the hat and say that the max volumetric effiecency(cylinder
filling ability) of an engine is 70 %. This number will occur at a narrow
rpm level and any level above or below it will decrease the VE number. This
is where the engine "likes to breathe" as that all american hot rod boy
would say. The only way to decrease the BMEP at this rpm level is to
restrict the filling ability further....and as Jack mentioned...lower the
throttle. THen BMEP will go down.
If running at this level and the load overcomes the torque, then the BMEP
goes up further at WOT due to increased load. Think of a Hydraulic
cylinder....without the load, there is no pressure. as the load goes up, so
does the pressure. This will give an aproximation of the concept. Not quite
just the same, because we have compressable fluids here...but you get the
idea. LOAD increases BMEP. Here is where you now have that 110% factor.
Other varibles are the ability of the engine to remove the heat....keep
bearings oiled..and so on that can be factored as coeffiecients Capt Ron if
you are looking for the logic in the Math. So they wont be the same for all
engines do to different factors here. That Liquid cooled Diesel ....or maybe
even that 682 compared to that 503 and 447 will have a coefiecient here much
better due to the liquid cooling. A 2 cycle, because of the heat removing
qualities of the Fuel ratio, is sensitive to this as we all know how fast
the temps go up my doing nothing to the load but just adjusting the air/fuel
ratio's.
I have read in previous post's about temps going up when throttles are
lowered. Well I am not sure but I would think that this is a function of a
carburator not maintaining a consistant ratio at different settings. but
thats a tangent...
Capt Ron, you are correct when you say that anything less than 100%hp/ rpm
level ..is .less output. But this is not related weather or not that engine
is "loaded and on its knees" do to the Load it is incurring.
Remember spark knock in your car when you mashed the throttle at low rpms
and it went away as you let off?
It is always blamed on low octane right?...well...low octane for the BMEP is
more specific and letting off the throttle decreases this pressure...and
knock goes away. these are related things. Like John posted, driving your
truck around in 5th at 25mph is a really good illustration of overloading an
engine at less than 100% hp/rpm. And of course he is right...it wont last
long thatway!
And Finally...Jerb, you ask about my backround...well, I'm just a dumb ole
farm boy who got his A&P ticket in the early 70's along with a commercial
multi rating and an engineering degree...who left the industry not long
after because it looked like it was gonna die, became a weedhopper dealer in
1979 (the first one east of the Mississippi my old buddy John Chotia told me
when I sighed on) I have been in the Engine biz one way or another my whole
life...went to Sweden as a young engineer and was employed on a design team
to develop a 2 cycle powered pole saw....entered into engine and equipment
sales from there....and I was Hired 12 years ago by Honda engine division as
the midwest USA rep. I handle all the OEM accounts in my territory as far as
supply and service education and....well...I got plenty to do lets just say.
I have been married to the same gal for 25 years and I have 2 grown kids
whom I am ashamed of about half the time, but I still luv em, and when I
think back of all the hot-roddin and engine building that my son and I have
done from go-karts to motorcycles to alcohol burnin open class pulling
tractors, I am proud that we spent that time together..but I wish he would
have learned more!....what else ya wanna klnow?....I aint lookin fer work an
no ya cant marry me!
Don Gherardini
FireFly 098
terrible how windy a fella gets when the snow is canopy deep aint it!
Have a good SuperBowl Sunday men.
Message 12
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: "Don Gherardini" <donghe@one-eleven.net>
Jack, I am not sure I understand your previous post completly..but to sounds
to me like you are hitting around the fuel saving techniques that lindberg
came up with and taught the pilots of ww 2, and are still practiced
today...and yes...if we had an inflight adjustable prop....which it looks
like affordable ones are about here...then we would have just what we
need....have you been looking at Ivos new Inflight adjustable ? could be the
answer to the range we all desire!
Don
Message 13
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: CaptainRon <CaptainRon@theriver.com>
Ok here is the definition for duty cycle and a nice concise explanation.
It still does not explain your prior claim of lower RPM means higher duty
cycle. Point of fact placing the following definition next to your prior
claim shows exactly the opposit. :-)
""" duty cycle
Duty cycle is the proportion of time during which a component, device, or
system is operated. The duty cycle can be expressed as a ratio or as a
percentage. Suppose a disk drive operates for 1 second, then is shut off for
99 seconds, then is run for 1 second again, and so on. The drive runs for
one out of 100 seconds, or 1/100 of the time, and its duty cycle is
therefore 1/100, or 1 percent.
The more a circuit, machine or component is used, the sooner it will wear
out. Therefore, the higher the duty cycle, the shorter the useful life, all
other things being equal. If the above-mentioned disk drive has a life
expectancy of 1,000,000 hours based on a 1 percent duty cycle, that same
device's expectancy would probably be about 500,000 hours based on a duty
cycle of 2 percent, and 2,000,000 hours based on a duty cycle of 0.5
percent."""""""""
In other words, it would be best if you would go revisit your math and enter
the proper correction. Afterwhich if you would like we can continue on the
rest of your scenario.
===================================
1/26/03 12:25Don Gherardini
> --> Kolb-List message posted by: "Don Gherardini" <donghe@one-eleven.net>
>
> George, and Capt Ron,
> The term Duty Cycle as designated as a % Has nothing to do with % of max
> Horsepower men. It is used as an indicator as to how long an engine(or
> component) will last at the work (duty) being preformed.
> The factors in rating duty cycle are several.
> For instance how long a connecting rod will last with(how many cycles) lets
> just use this example so this post wont be so long.
>
> Q. At what rpm is the maximum pressure applied to the rod?
> A. At the rpm where the highest Volumetric effiency occurs.
>
> Q. How can we find this rpms level?
> A. It will be the level of peak torque on the curve. Here the BMEP will be
> the highest, and VE( volumetric effeicency) is highest, and likely is not at
> max rated rpm.
>
> Q.why is the horspower peak not at this point?
> A. because Torque is a measured unit and HP is calculated (not measured)
> with a time factor added .(and the HP formula sometimes subject to marketing
> influeces not relating to engineering values!, particularly in todays
> market) Not All manufacturers use Watts hp formula anymore....dont get me
> started down that road....
>
> OK...we have established that the most force will be applied to the rod when
> the cylinder pressure is the highest...thays is pretty straight forward.
> now...how long do we WANT it to last? Herein is the Term Duty cycle's reason
> for being. So an engineer on a design Team can decide on just how strong of
> a rod to make and just how good of a bearing to request from his vendor. The
> market will require the Duty Cycle or the product will not be saleable.
>
> Now, as we all understand he engine being an air pump...and lets just pull a
> number out of the hat and say that the max volumetric effiecency(cylinder
> filling ability) of an engine is 70 %. This number will occur at a narrow
> rpm level and any level above or below it will decrease the VE number. This
> is where the engine "likes to breathe" as that all american hot rod boy
> would say. The only way to decrease the BMEP at this rpm level is to
> restrict the filling ability further....and as Jack mentioned...lower the
> throttle. THen BMEP will go down.
>
> If running at this level and the load overcomes the torque, then the BMEP
> goes up further at WOT due to increased load. Think of a Hydraulic
> cylinder....without the load, there is no pressure. as the load goes up, so
> does the pressure. This will give an aproximation of the concept. Not quite
> just the same, because we have compressable fluids here...but you get the
> idea. LOAD increases BMEP. Here is where you now have that 110% factor.
> Other varibles are the ability of the engine to remove the heat....keep
> bearings oiled..and so on that can be factored as coeffiecients Capt Ron if
> you are looking for the logic in the Math. So they wont be the same for all
> engines do to different factors here. That Liquid cooled Diesel ....or maybe
> even that 682 compared to that 503 and 447 will have a coefiecient here much
> better due to the liquid cooling. A 2 cycle, because of the heat removing
> qualities of the Fuel ratio, is sensitive to this as we all know how fast
> the temps go up my doing nothing to the load but just adjusting the air/fuel
> ratio's.
> I have read in previous post's about temps going up when throttles are
> lowered. Well I am not sure but I would think that this is a function of a
> carburator not maintaining a consistant ratio at different settings. but
> thats a tangent...
>
> Capt Ron, you are correct when you say that anything less than 100%hp/ rpm
> level ..is .less output. But this is not related weather or not that engine
> is "loaded and on its knees" do to the Load it is incurring.
> Remember spark knock in your car when you mashed the throttle at low rpms
> and it went away as you let off?
> It is always blamed on low octane right?...well...low octane for the BMEP is
> more specific and letting off the throttle decreases this pressure...and
> knock goes away. these are related things. Like John posted, driving your
> truck around in 5th at 25mph is a really good illustration of overloading an
> engine at less than 100% hp/rpm. And of course he is right...it wont last
> long thatway!
>
> And Finally...Jerb, you ask about my backround...well, I'm just a dumb ole
> farm boy who got his A&P ticket in the early 70's along with a commercial
> multi rating and an engineering degree...who left the industry not long
> after because it looked like it was gonna die, became a weedhopper dealer in
> 1979 (the first one east of the Mississippi my old buddy John Chotia told me
> when I sighed on) I have been in the Engine biz one way or another my whole
> life...went to Sweden as a young engineer and was employed on a design team
> to develop a 2 cycle powered pole saw....entered into engine and equipment
> sales from there....and I was Hired 12 years ago by Honda engine division as
> the midwest USA rep. I handle all the OEM accounts in my territory as far as
> supply and service education and....well...I got plenty to do lets just say.
> I have been married to the same gal for 25 years and I have 2 grown kids
> whom I am ashamed of about half the time, but I still luv em, and when I
> think back of all the hot-roddin and engine building that my son and I have
> done from go-karts to motorcycles to alcohol burnin open class pulling
> tractors, I am proud that we spent that time together..but I wish he would
> have learned more!....what else ya wanna klnow?....I aint lookin fer work an
> no ya cant marry me!
>
> Don Gherardini
> FireFly 098
> terrible how windy a fella gets when the snow is canopy deep aint it!
>
> Have a good SuperBowl Sunday men.
>
>
>
>
>
>
Message 14
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
--> Kolb-List message posted by: Bob Bean <slyck@frontiernet.net>
Hey capn' Ron, lighten up. We got enough lawyers in the land awready.
-BB do not archive
Message 15
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: jerb <ulflyer@airmail.net>
Where is the proper place to run an engine for optimum best performance,
that being a comprise between climb and cruise, at peak torque or peak HP?
jerb
DO NOT ARCHIVE
Message 16
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: GeoR38@aol.com
In a message dated 01/26/2003 11:16:59 AM Eastern Standard Time,
CaptainRon@theriver.com writes:
>
> --> Kolb-List message posted by: CaptainRon <CaptainRon@theriver.com>
>
> 1/26/03 7:39GeoR38@aol.com
>
> >I have a problem with the 110% duty cycle senario as
> >well as I KNOW that HP or power is a product of Torque times Speed times a
> >constant.....if the prop is pitched too high, the torque required to reach
> a
> >certain speed is too high for the engine at hand, therefore the HP is less
> >than 110% in my book.
> ===============================
>
> I agree. I wanted to stay out of it but since you brought it up I might as
> well chime in.
>
> I think he needs to define for us his defifnition of Duty Cycle before I
> buy
> into his analysis. If 100% of Hp is 6200 rpms, by definition anything less
> than 6200 rpms at max torque is less than 100% output. If one climbs and
> his
> engine is at 5800 rpms than he is only getting 58/62= 93% of his engin's
> HP.
> On a 65 hp rotax that would work out to .93(65)= 60.45 of his engines
> available HP. How does he get 110% duty cycle in his example does not seem
> to be mathematically possible.
>
> I think we need his definition of a Duty Cycle. So far the claim defies
> logic. :-)
>
with ya 100% capt Ron, this is exactly the way I look at it as well, but I
think electrically instead of mechanically so the definitions may be the
clinker here. I am looking at his Duty Cycle like "service factor" marked on
the nameplate of electric motors and that may be wrong IAW his definition of
Duty Cycle.
The only way I was aware that the HP could be exceeded was by use of a
Resonant chamber connected to the exhaust ( which I'm sure gave Cuyunna a bad
name as many of their engines had them even though the pilots KNEW that it
was a risk to firewall them for too long....shoot....I did it myself in my
old pterodactyl and ended up listening to the silence before forced landing
one day! ).
I must admit, however, I really do not have a clue why the EGT's go up when
you unload after a steep climb....well, I have a clue, but it may not be
correct...namely that the carburator is automatically leaner at 3/4 throttle
than at 100% throttle....dunno bout this for sure, but I try never to run at
3/4 thottle too long...but I watch the egt's like a hawk anyway.
George Randolph
George Randolph
Message 17
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: John Hauck <jhauck@sw.rr.com>
> I must admit, however, I really do not have a clue why the EGT's go up when
> you unload after a steep climb....well, I have a clue, but it may not be
> correct...namely that the carburator is automatically leaner at 3/4 throttle
> than at 100% throttle....dunno bout this for sure, but I try never to run at
> 3/4 thottle too long...but I watch the egt's like a hawk anyway.
>
> George Randolph
George/Gang:
It all goes back to prop loading a two stroke.
They are very sensitive to loading and unloading.
Unload and the EGT goes up. Load up the prop and
it come back down.
Try this next time you fly a two stroke:
Cruise power, say...........5,800 rpm. Straight
and level flight.
Don't touch the throttle. Leave it where it is
for 5,800 rpm.
Note the EGT reading and pull the nose up. The
EGT goes down quick.
Go back to straight and level flight. Leave the
throttle set at 5,800 rpm. Push the nose over.
The EGT goes up quick.
The Rotax engines are set up at the factory to be
propped to bump the red line, WOT straight and
level flight. They are jetted for this profile.
The prop must be pitched to match the profile.
If the engine is pitched correctly, there is no
need to play swapping games with jets, spark plugs
or anything else. In addition, you have the best
of two worlds with a non-inflight adjustable
prop: Best climb and cruise.
Carb jetting and profile is also a major factor in
changing EGT. That is why it is important to
monitor EGT and stay out of those zones that tend
to lean out the engine and raise EGT.
Works for me....................
john h
DO NOT ARCHIVE
Message 18
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | 110% duty cycle vs manifold pressure |
--> Kolb-List message posted by: Richard Pike <rwpike@charter.net>
Something that I think is being overlooked in this whole question about
prop pitch vs RPM's vs load vs 110% duty cycle is that the aviation
community has been dealing with this situation for many years and it is
called manifold pressure.
When you fly an aircraft with a constant speed prop, you decide what
manifold pressure you want to fly it at, and once you are up at altitude
you adjust the prop pitch and throttle to give you a certain manifold
pressure at a certain rpm, such as "23 squared", 2,300 rpm at 23" of
manifold pressure or some such similar value.
We do not have constant speed props, but we have ground adjustable props,
(or Ivo inflight adjustables) and we can come up with the same results
through a more tedious method. Why would it not be valid to install a
manifold vacuum gauge (JC Whitney sells them for $9) and then through trial
and error determine how to juggle pitch, throttle setting and rpm to give
you a "happy engine?" Just because we do not use constant speed props does
not change anything. We are arguing about the exact issue that complex
aircraft use manifold pressure gauges to resolve, the inter relationship
between prop pitch, throttle setting, and rpm's.
It seems to me that getting the desired cruise speed at an rpm that you &
the engine are happy with (somewhere between 5,000 and 5,800, depending on
your prejudices and preconceived notions) at the lowest reasonable manifold
pressure (determined by trial and error, in the case of Rotax 2-strokes)
would give the best possible service life out of the engine, and most
economical fuel burn.
Or am I missing something?
Richard Pike
MKIII N420P (420ldPoops)
Message 19
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Just a bit nippy... |
--> Kolb-List message posted by: "abbygirlk9" <abbygirlk9@netzero.net>
Hey list, I wanted to write & encourage you builders out there especially if you
need a shot in the arm to keep plugging away with that Kolb project. A few
months back Big Lar reported taking a ride with George Thompson in his Firestar
II and scouting the area north of Prescott, AZ looking for critters and such.
Well I did the same last Saturday and it was a needed infusion to remind
me of why I was making a career out of building a plane and a trailer to put it
in.....it was great to finally take a hop in the same plane that I have been
constructing for the past 2 years. After reading Big Lar's post about his hop
(and seeing the pictures) I decided to ask George for the same .....yaa, what
a cool ride (actually about 35 degrees) in very calm & clear air. George's
FS II was rock stable and flew hands off, now that's what I want! The point of
course is that sometimes a person needs more than just reading the list for
a boost - - get a ride and experience the Kolb, and for some it may be for the
first time.
Stephen Feldmann
Glendale, AZ
Firestar II 400+ hours in construction so far
Firestar II custom trailer nearly done after 6 months
Message 20
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: "Jeffrey Jones" <jeffrey.jones@fuse.net>
John/Others
I was wondering where this thread was going........ Your explanation is
exactly what I am experiencing now. My 503 is pitched to WOT at 6400 and I
have been thinking about taking it to 6800 just as you said and now I will.
I also have experienced the EGT bounce at that point you mentioned.
Gaining knowledge from your experiences. Thanks!
Jeff
Do Not Archive
----- Original Message -----
From: "John Hauck" <jhauck@sw.rr.com>
Subject: Re: Kolb-List: 110% duty cycle?
> --> Kolb-List message posted by: John Hauck <jhauck@sw.rr.com>
>
>
> > I must admit, however, I really do not have a clue why the EGT's go up
when
> > you unload after a steep climb....well, I have a clue, but it may not be
> > correct...namely that the carburator is automatically leaner at 3/4
throttle
> > than at 100% throttle....dunno bout this for sure, but I try never to
run at
> > 3/4 thottle too long...but I watch the egt's like a hawk anyway.
> >
> > George Randolph
>
> George/Gang:
>
> It all goes back to prop loading a two stroke.
> They are very sensitive to loading and unloading.
> Unload and the EGT goes up. Load up the prop and
> it come back down.
>
> Try this next time you fly a two stroke:
>
> Cruise power, say...........5,800 rpm. Straight
> and level flight.
>
> Don't touch the throttle. Leave it where it is
> for 5,800 rpm.
>
> Note the EGT reading and pull the nose up. The
> EGT goes down quick.
>
> Go back to straight and level flight. Leave the
> throttle set at 5,800 rpm. Push the nose over.
> The EGT goes up quick.
>
> The Rotax engines are set up at the factory to be
> propped to bump the red line, WOT straight and
> level flight. They are jetted for this profile.
> The prop must be pitched to match the profile.
> If the engine is pitched correctly, there is no
> need to play swapping games with jets, spark plugs
> or anything else. In addition, you have the best
> of two worlds with a non-inflight adjustable
> prop: Best climb and cruise.
>
> Carb jetting and profile is also a major factor in
> changing EGT. That is why it is important to
> monitor EGT and stay out of those zones that tend
> to lean out the engine and raise EGT.
>
> Works for me....................
>
> john h
>
> DO NOT ARCHIVE
>
>
Message 21
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: John Hauck <jhauck@sw.rr.com>
> I was wondering where this thread was going........ Your explanation is
> exactly what I am experiencing now. My 503 is pitched to WOT at 6400 and I
> have been thinking about taking it to 6800 just as you said and now I will.
> Jeff
Jeff/Gang:
I should have included this with my previous
post. Max continuous power red line for the two
strokes is 6,500 rpm. Prop it to bump 6,500 rpm
WOT straight and level flight. If you prop it for
6,800 rpm you will be too lightly pitched, lose
cruise, and your EGTs will run higher.
IIRC (if not somebody will correct me) static rpm
should be 6,200 to 6,300 to get 6,500. Depends on
what prop you are using too. But that will put
you in the ball park.
john h
Message 22
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Fuselage tube / wing brace alignment |
--> Kolb-List message posted by: "Ed Bonsell" <ebonsell@earthlink.net>
Hi Friends,
I just got back on the list. This is my first post after getting off last spring.
I have an 86 firestar I flew around eastern Pennsylvania for 12 or 13 years
before it was partially damaged in a hanger fire. Most of the damage was to the
fabric. I have been too busy to work on it during the spring, summer, and fall.
Last year I decided to build a new set of wings using the 7 rib version
instead of the 5 ribs in the original wing.
First I must say I bought the kit from the original Kolb company in Pa. All the
parts and fittings were welded pretty much true and square and I had no trouble
aligning the H sections in the wing or fuselage tube. How ever this wasn't
the case when I got new parts. The first problem I had was with the H sections
for the wings. I drilled the bolt holes and 4 holes to line up the rivets in
the wing tube, first spending hours making sure they were perfectly lined up.
When I put the H sections in position the bolt holes were so far off they couldn't
be used. I ended up sending them back and asking for a pair that were square.
The second pair came ok.
So, the problem I'm having now.
I just tried to temporarily assemble the right inboard wing rib, wing tube, and
diagonal brace to see how everything was going to line up. Well, they don't.
It looks like the rib is not square. Looking from the front it seems to curve
in toward the root tube as it goes back toward the rear spar. The tube that holds
the rear spar tilts up so that when you slip the rear spar over it, it will
not run parallel to the main tube without tension on it. And the diagonal brace,
made to the correct length is now too short to line up at the correct place
at each end.
So now what, Anybody have any strait inboard wing ribs for a firestar lying around?
Then again maybe I'll start looking for a mark II instead.
Ed Bonsell
Ft. Washington Pa
Message 23
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: Richard Pike <rwpike@charter.net>
Whenever you prop your engine to the point that it will rev higher than
normal, you stand the risk of having the engine lean out excessively when
you are at partial throttle and the engine is in a reduced load situation,
along with very high EGT's.
This has been discussed before on the list so I will not review it, but be
careful.
If you are not familiar with this situation, check out
http://www.bcchapel.org/pages/0003/pg11.htm
Richard Pike
MKIII N420P (420ldPoops)
Do Not Archive
At 11:01 PM 1/26/03 -0500, you wrote:
>--> Kolb-List message posted by: "Jeffrey Jones" <jeffrey.jones@fuse.net>
>
>John/Others
>
>I was wondering where this thread was going........ Your explanation is
>exactly what I am experiencing now. My 503 is pitched to WOT at 6400 and I
>have been thinking about taking it to 6800 just as you said and now I will.
>I also have experienced the EGT bounce at that point you mentioned.
>
>Gaining knowledge from your experiences. Thanks!
>
>Jeff
>
>Do Not Archive
>
>
>----- Original Message -----
>From: "John Hauck" <jhauck@sw.rr.com>
>To: <kolb-list@matronics.com>
>Subject: Re: Kolb-List: 110% duty cycle?
>
>
> > George/Gang:
> >
> > It all goes back to prop loading a two stroke.
> > They are very sensitive to loading and unloading.
> > Unload and the EGT goes up. Load up the prop and
> > it come back down.
> >
> > Try this next time you fly a two stroke:
> >
> > Cruise power, say...........5,800 rpm. Straight
> > and level flight.
> >
> > Don't touch the throttle. Leave it where it is
> > for 5,800 rpm.
> >
> > Note the EGT reading and pull the nose up. The
> > EGT goes down quick.
> >
> > Go back to straight and level flight. Leave the
> > throttle set at 5,800 rpm. Push the nose over.
> > The EGT goes up quick.
> >
> > The Rotax engines are set up at the factory to be
> > propped to bump the red line, WOT straight and
> > level flight. They are jetted for this profile.
> > The prop must be pitched to match the profile.
> > If the engine is pitched correctly, there is no
> > need to play swapping games with jets, spark plugs
> > or anything else. In addition, you have the best
> > of two worlds with a non-inflight adjustable
> > prop: Best climb and cruise.
> >
> > Carb jetting and profile is also a major factor in
> > changing EGT. That is why it is important to
> > monitor EGT and stay out of those zones that tend
> > to lean out the engine and raise EGT.
> >
> > Works for me....................
> >
> > john h
> >
> > DO NOT ARCHIVE
> >
> >
>
>
Message 24
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: "CaptainRon" <captainron@theriver.com>
Without looking at the Torque tables that Rotax provides, I can say that in
general (and probably true for Rotax as well) Torque rises up sharply and
then levels off and stays flat through most of the operating range then
kinda starts falling off.. The way I see it is that the moment arm imparted
on the crank per power stroke reaches a certain level and basically remains
within it, increasing cylinder pressure under a constant ambiant
(atmospheric)conditions with more fuel will reache a point of diminishing
returns, thus the seemingly flat torque curves. The moment arm on the crank
is just so efficient in the transfer of power, that a small incremental
increase by addition of more fuel will only translate to just so slight
additional torque. The only way to increase the thrust is by faster rpm's,
or more work per minute.The simple answere is more RPM's more Go,,, but up
to the engine design limits, and the prop's efficincy range. Why egt's go up
after you level off, is strange and I cannot off hand see the reason for it
except if when you level off unloading the prop you also increase your rpm.
Which I guess you would on a fixed pitch prop. If your rpms go up you are
sending more hot exaust gas per minute unto the probe so it will register
higher. Now if I am told that you climb at 5800 and you level off at 5800
and you still have a rise in egt *all else remains constant*, then its just
magic. (and I don't believe in magic) :-)
============================
----- Original Message -----
From: "jerb" <ulflyer@airmail.net>
Subject: Re: Kolb-List: 110% duty cycle?
> --> Kolb-List message posted by: jerb <ulflyer@airmail.net>
>
> Where is the proper place to run an engine for optimum best performance,
> that being a comprise between climb and cruise, at peak torque or peak HP?
> jerb
>
> DO NOT ARCHIVE
>
>
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|