Today's Message Index:
----------------------
1. 02:53 AM - Re: Preservation of two cycle engines (Vincehallam@aol.com)
2. 04:01 AM - Re: Preservation of two cycle engines ()
3. 05:13 AM - Re: Honda's for aircraft (dixieshack@webtv.net (Mike and Dixie Shackelford))
4. 06:39 AM - Re: Preservation of two cycle engines (SGreenpg@aol.com)
5. 07:02 AM - Jabiru 2200 (Dallas Shepherd)
6. 08:23 AM - Larry's J-5 (Larry Bourne)
7. 09:59 AM - Fuselage Tube Alignment (tom sabean)
8. 10:49 AM - [ Paul Petty ] : New Email List Photo Share Available! (Email List Photo Shares)
9. 11:49 AM - Re: Fuselage Tube Alignment (CaptainRon)
10. 12:34 PM - Re: Fuselage Tube Alignment (John Hauck)
11. 12:49 PM - Re: Fuselage Tube Alignment (John Hauck)
12. 01:11 PM - Re: Fuselage Tube Alignment (John Hauck)
13. 01:43 PM - Fw: Pics (Larry Bourne)
14. 02:02 PM - Re: Fuselage Tube Alignment (Larry Bourne)
15. 04:19 PM - Weather (Larry Bourne)
16. 04:26 PM - non-kolb but very funny (Paul Petty)
17. 05:09 PM - Re: Fuselage Tube Alignment (CaptainRon)
18. 06:44 PM - Re: Re: Honda's for aircraft message of Fri, 24 Jan 2003 23:56:08 -0800 (Don Gherardini)
19. 07:03 PM - Re: Re: Honda's for aircraft message of Fri, 24 Jan 2003 23:56:08 -0800 (Richard Harris)
20. 07:29 PM - Re: Weather ()
21. 08:34 PM - 110% duty cycle? (Richard Pike)
22. 10:36 PM - Re: 110% duty cycle? (WhiskeyVictor36@aol.com)
Message 1
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| Subject: | Re: Preservation of two cycle engines |
--> Kolb-List message posted by: Vincehallam@aol.com
Getting V-belts tight enough to transmit the power withot slippage was a
problem I think .The side loads on the lay shaft caused bearing failures and
once per cycle bending loads [in the lay shaft].Gearboxes were always a
difficult area on real aircraft [oops] and required alot ofdevelopment for
each individual installation lockheed orions had big problems with props
flailing right off , Our bristol helicopters had their gearboxes
deliberately built out of line to a small degree to line up under nomal
loads.Inever did like the twin rotaxes they are so intolerant of anyhing
under 2500rpm on light load My own preference is forget lfocussing only on
theoretical efficiency ,save the weight,cost,hassle of the gearbox and
tallground or boom clearances ,pack in a wee bit more power usew direct
drive
[I await the deluge] vnz
Message 2
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| Subject: | Re: Preservation of two cycle engines |
--> Kolb-List message posted by: <rowedl@highstream.net>
Vince,
Sounds to me like the ideal solution would be a larger bore Jabiru 2200,
maybe a 2800, that would make the 80 hp at a lower max RPM. Having first
flown ultralights in the early 80s in a direct drive Pterodactyl Ptraveler.
(Cuyuna 430D with a 36" diameter prop) I can tell you that there is nothing
theoretical about using redrives. My first flight in a Dac with a 2 to 1
reduction and a 54" prop was the day of my conversion to redrives. That
redrive easily doubled the climb rate in Dacs, and the higher ratios are
even better.
Denny
PS:(If they build it we will buy)
do not archive
----- Original Message -----
From: <Vincehallam@aol.com>
Subject: Re: Kolb-List: Preservation of two cycle engines
> --> Kolb-List message posted by: Vincehallam@aol.com
>
> Getting V-belts tight enough to transmit the power withot slippage was a
> problem I think .The side loads on the lay shaft caused bearing failures
and
> once per cycle bending loads [in the lay shaft].Gearboxes were always a
> difficult area on real aircraft [oops] and required alot ofdevelopment for
> each individual installation lockheed orions had big problems with props
> flailing right off , Our bristol helicopters had their gearboxes
> deliberately built out of line to a small degree to line up under nomal
> loads.Inever did like the twin rotaxes they are so intolerant of anyhing
> under 2500rpm on light load My own preference is forget lfocussing only on
> theoretical efficiency ,save the weight,cost,hassle of the gearbox and
> tallground or boom clearances ,pack in a wee bit more power usew direct
> drive
> [I await the deluge] vnz
>
>
Message 3
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| Subject: | Re: Honda's for aircraft |
message of Fri, 24 Jan 2003 23:56:08 -0800
--> Kolb-List message posted by: dixieshack@webtv.net (Mike and Dixie Shackelford)
'Morning guys....
Sounds like Don just eliminated Honda as a possible choice to power our
aircraft.
If all those operating parameters must be adhered to in order for Honda
industrial engines to operate without self-destructing, it would appear
that they may be under-engineered in those areas.....I thought just the
opposite was the norm. Shock loads from a fan unloading?
Gear lash in a transmission or speed reducer?
We ARE talking Honda four strokes here, aren't we? I'd bet the problem
is more in the warranty coverage than the engine.
Granted, some industrial applications are constant-load, but what
about water and trash pumps, air compressors, welders, and others that
see continually changing and sometimes sudden shock loads like the above
trash pump picking up a slug of mud or a rock? These guys usually are
direct-driven with no means for absorbing the sudden encountered shocks.
No criticism.....just a question....
Hey Lar.....those pics that John posted.....does that mean you
bought the J-5?
You gonna put training skids on the wingtips??
Sorry, I couldn't resist...hehehe. Instead of driving to the Least
Coast next summer, fly the Cruiser and stick to the magenta
airports....they're more fun and user-friendly. 'Course ya know that.
Bring your fishing pole...I've got some bass and BIG cats in my pond.
Nothing Kolb-related here, but the list has been light lately....
Mike in WV
do not archive
Message 4
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| Subject: | Re: Preservation of two cycle engines |
--> Kolb-List message posted by: SGreenpg@aol.com
Don,
I didn't mention that I was using a "C" gearbox which has a torsional
coupling between the crankshaft and gearbox.
Steven
Message 5
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--> Kolb-List message posted by: "Dallas Shepherd" <cen23954@centurytel.net>
Kolb list:
I have decided not to rebuild my Kolb Mark 3 after my Thanksgiving day
crash and will sell the Jabiru 2200 engine off of it. It was not hurt in
the crash as the plane came straight down and hit on the nose. It has 98
hours on it and the TBO for serial number 22A642 is now 1000 hours. You
might check me on that 1000 hours, but I think I read that. After checking
on some used engine prices I will sell it for $5000. If you want the EIS,
58" Warp Drive prop and the Kolb engine mount it will be $5500. However,
the Jabiru company and Warp Drive recommend not using this prop anymore as
they have found some cracks in the hub of several and instruct users to use
a dye penetrate to look for them. I have not done this as I had made
arrangements to put on a wood two blade prop, but never got there. This
price will be plus shipping or you can pick it up here. The prop can be
used on a gear box arrangement such as rotax. Please contact me off list.
Dallas Shepherd 983 Sheid Road, Norfork, Arkansas, 72658
Phone 870 499 5172
e-mail cen23954@ centurytel.net
DO NOT ARCHIVE
Message 6
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--> Kolb-List message posted by: "Larry Bourne" <biglar@gogittum.com>
Yup, bought the J-5, and week after next will start watching for a weather
window to go get it from the northwest, (bad time of year) and
nope.................no training wheels. I'm signed off in taildraggers,
and this ones a dandy. Vamoose made it up to the high desert
yesterday, and should have his new suit in about 2 weeks. The wings look
great - almost smooth across the ribs, but the fabric is tight. Don't know
how he managed that. Then I'll be a 2 airplane bachelor. I sent John
some pics of moving Vamoose, so maybe I can talk him into publishing those,
too. I forgot to transfer my FTP into the new computer. Gotta do that.
Also, to my knowledge, the only time there's backlash in the gears of a
redrive, is if it's idled too slowly. Otherwise it's a steady pressure,
with the cushion of the prop in air providing some (??) shock dampening.
Big Lar. Do not Archive.
Larry Bourne
Palm Springs, CA
Kolb Mk III - Vamoose
www.gogittum.com
----- Original Message -----
From: "Mike and Dixie Shackelford" <dixieshack@webtv.net>
Subject: Kolb-List: Re: Honda's for aircraft message of Fri, 24 Jan 2003
23:56:08 -0800
> --> Kolb-List message posted by: dixieshack@webtv.net (Mike and Dixie
Shackelford)
>
> 'Morning guys....
> Sounds like Don just eliminated Honda as a possible choice to power our
> aircraft.
> If all those operating parameters must be adhered to in order for Honda
> industrial engines to operate without self-destructing, it would appear
> that they may be under-engineered in those areas.....I thought just the
> opposite was the norm. Shock loads from a fan unloading?
Message 7
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| Subject: | Fuselage Tube Alignment |
--> Kolb-List message posted by: tom sabean <sabean@ns.sympatico.ca>
Listers,
When I installed the H-brace in the fuselage tube I followed the
instructions but when I fit the tube into the cage it appears not to be
lined up properly.
It almost looks like either the internal H-brace isn't exactly 90
degrees or the frame isn't square in the area of the bolt holes.
When I fit the bolt through it slides in until it gets to the opposite
side cage attachment point and hangs up there. It lines up vertically
but looks like it may be off approximately 1/8th of an inch in the
horizontal plane.
Anybody else run into this problem or have any suggestions.
Thanks,
Tom Sabean
Mark111xtra
Message 8
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| Subject: | [ Paul Petty ] : New Email List Photo Share Available! |
--> Kolb-List message posted by: Email List Photo Shares <pictures@matronics.com>
A new Email List Photo Share is available:
Poster: Paul Petty <ppetty@c-gate.net>
Subject: Kolb? Who When Model?
http://www.matronics.com/photoshare/ppetty@c-gate.net.01.25.2003/index.html
--------------------------------------------
o EMAIL LIST PHOTO SHARE
Share your files and photos with other List members simply by
emailing the files to:
pictures@matronics.com
Please view the typical Share above and include the Description Text
Fields as shown along with your submission of files and photos.
o Main Photo Share Index:
http://www.matronics.com/photoshare
--------------------------------------------
Message 9
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| Subject: | Re: Fuselage Tube Alignment |
--> Kolb-List message posted by: CaptainRon <CaptainRon@theriver.com>
What does it hang up on? The cage bracket or the tube itself. If its only
1/8 I would think that it would be safe to bore it out nicely. I am about
where you are, just starting on the tube to cage mating, and aligning so I
don't have a good visual on the problem. But if its only 1/8 of an inch I
doubt it will compromise strength in any way, there is still plenty of metal
there to hold everything with a good margine.
do not archive
==============================
Message 10
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| Subject: | Re: Fuselage Tube Alignment |
--> Kolb-List message posted by: John Hauck <jhauck@sw.rr.com>
> When I installed the H-brace in the fuselage tube I followed the
> instructions but when I fit the tube into the cage it appears not to be
> lined up properly.
> Tom Sabean
Tom/Gang:
Seems to be a common problem. I built three
different Kolbs and had similar problem with all
of them.
Here's what I did:
1. Try rotating tail boom 180 deg. If that
doesn' work, go to step 2.
2. Take an old 3/8", I think, bolt, grind a nice
bevel on the threaded end. Tap it through the
fuselage and "H" brace. Now, take the good bolt
and use it to back the old bolt out. Might also
use some persuasion, in the form of a two by four,
to lever the vertical tubes at the rear to the
cage. Usually, just a little help will do it.
When the 4130 fuselages are welded up, there is a
lot of movement as the tubes are welded, heated
and cooled. Impossible to get them to line up
perfectly all the time. This is also true of
smaller 4130 peices that are welded.
john h
Message 11
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| Subject: | Re: Fuselage Tube Alignment |
--> Kolb-List message posted by: John Hauck <jhauck@sw.rr.com>
> If its only
> 1/8 I would think that it would be safe to bore it out nicely.
Captain Ron
Ron/Gang:
Recommend you take a deeper look prior to
enlarging that hole to accept the "H" brace bolt.
To bore out the 3/8" hole to get the 1/8"
clearance you need would require a 1/2" bit.
I have to disagree on enlarging the hole to get
the bolt to align. The attachment at the "H"
brace on the tail boom is a critical load bearing
component on the fuselage and the "H" brace. Not
only does this fitting take a Hell of a beating in
the air, but even more so on the ground taxiing on
rough fields. Also gets loaded up pretty good
during trailering.
If you look back on the history of Kolb crashes
where a tail boom fails during the crash, it
always fails at the rear end of the "H" brace.
We need to be extremely careful handing out
information that deviates from the builder's
instruction manual.
Take care,
john h
Message 12
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| Subject: | Re: Fuselage Tube Alignment |
--> Kolb-List message posted by: John Hauck <jhauck@sw.rr.com>
> To bore out the 3/8" hole to get the 1/8"
> clearance you need would require a 1/2" bit.
> john h
Gang:
The above is wrong. Would take a 5/8 bit to get
the 1/8" side clearance on a 3/8" hole. I
theenk! Hell, what do I know. :-)
john h
Message 13
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--> Kolb-List message posted by: "Larry Bourne" <biglar@gogittum.com>
John was good enuf to post the pictures of Vamoose going for a truck ride
yesterday, so here they are. 3rd pic is the completed wings. Those of you
in the frozen east, might notice the background in the pic of the truck.
Gotta rub it in now, cause I'll be crying next summer.
GoGittin'em Lar.
Larry Bourne
Palm Springs, CA
Kolb Mk III - Vamoose
www.gogittum.com
----- Original Message -----
From: "John Hauck" <jhauck@sw.rr.com>
Subject: Pics
> Lar:
>
> The 3 new pics of Vamoose are posted:
>
> http://home.sw.rr.com/jhauck/Flying%20Friends/
>
> I'll give you the privilege of posting them to the
> Kolb List.
Message 14
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| Subject: | Re: Fuselage Tube Alignment |
--> Kolb-List message posted by: "Larry Bourne" <biglar@gogittum.com>
I had the same problem, but not quite 1/8". Mine was hanging the bolt up
where it tried to come out from the steel H-brace thru the aluminum tail
boom wall. I took a round file, and gently took a little off one side on
the front of the hole, and a matching amount on the back side of the
opposite hole, rather than taking the whole 1/8" off of one side of the tail
boom. Also clean up the hole thru the H-brace, but be careful. Don't
remove a lot of metal on this critical component. Go a bit at a time with a
fine tooth file; it doesn't take much, and you'll hardly see the "ovalling"
on each side. It's still tight on the top and bottom, so I doubt if that
little bit would compromise strength. John's suggestion of turning the
H-brace 180 deg. is a good one. You can rotate it 180 deg in the tube, or
flip it end for end. Mine was way out one way, and only a little out the
other. Yours just might line up.................it's worth a try. My
H-brace was a little large for the tube, and I was scared to death of
scratches inside the tailboom. I used some Quick-Grip rubber faced bar
clamps, and squeezed the tube a little from top to bottom, and the brace
slid right in. It takes quite a bit of pressure - that tube is tough. Also
be sure to check the brace for rough spots that might cause those dreaded
scratches. It's gotta be SMooooothhh. Big Lar.
Larry Bourne
Palm Springs, CA
Kolb Mk III - Vamoose
www.gogittum.com
----- Original Message -----
From: "tom sabean" <sabean@ns.sympatico.ca>
Subject: Kolb-List: Fuselage Tube Alignment
> --> Kolb-List message posted by: tom sabean <sabean@ns.sympatico.ca>
>
> Listers,
>
> When I installed the H-brace in the fuselage tube I followed the
> instructions but when I fit the tube into the cage it appears not to be
> lined up properly.
> It almost looks like either the internal H-brace isn't exactly 90
> degrees or the frame isn't square in the area of the bolt holes.
> When I fit the bolt through it slides in until it gets to the opposite
> side cage attachment point and hangs up there. It lines up vertically
> but looks like it may be off approximately 1/8th of an inch in the
> horizontal plane.
> Anybody else run into this problem or have any suggestions.
>
> Thanks,
> Tom Sabean
> Mark111xtra
>
>
Message 15
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--> Kolb-List message posted by: "Larry Bourne" <biglar@gogittum.com>
OH DEAR ! ! ! 83 deg in Palm Springs today, and my swamp cooler isn't working
right. Got stuffy and warm in here, so had to fire up the A/C. Hate ta waste
all that electicity at this time of year, ya know. :-) :-) Lar.
Do not Archive.
Larry Bourne
Palm Springs, CA
Kolb Mk III - Vamoose
www.gogittum.com
Message 16
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| Subject: | non-kolb but very funny |
SPAM_PHRASE_00_01, USER_AGENT_OE, USER_IN_WHITELIST)
--> Kolb-List message posted by: "Paul Petty" <ppetty@c-gate.net>
Hello Kolbers.
Just had to share this one with the list.
Australian Airline humor...
This is from maintenance logs of Qantas: Never let it be said that
ground crews and engineers lack a sense of humor.
Here are some actual logged maintenance complaints by QANTAS pilots and
the corrective action recorded by mechanics. By the way, Qantas is the
only major airline that has never had an accident.
P stands for the problem the pilots entered in the log
S stands for the corrective action taken by the mechanics.
P: Left inside main tire almost needs replacement.
S: Almost replaced left inside main tire.
P: Test flight OK, except autoland very rough.
S: Autoland not installed on this aircraft.
P: Something loose in cockpit.
S: Something tightened in cockpit.
P: Dead bugs on windshield.
S: Live bugs on backorder.
P: Autopilot in altitude-hold mode produces a 200-fpm descent.
S: Cannot reproduce problem on ground.
P: Evidence of leak on right main landing gear.
S: Evidence removed.
P: DME volume unbelievably loud.
S: DME volume set to more believable level.
P: Friction locks cause throttle levers to stick.
S: That's what they're there for!
P: IFF inoperative.
S: IFF always inoperative in OFF mode.
P: Suspected crack in windscreen.
S: Suspect you're right.
P: Number 3 engine missing. (note: this was for a piston-engined
airplane; the pilot meant the engine was not running smoothly)
S: Engine found on right wing after brief search.
P: Aircraft handles funny.
S: Aircraft warned to straighten up, fly right, and be serious.
P: Radar hums.
S: Reprogrammed radar with words.
P: Mouse in cockpit.
S: Cat installed
Sorry folks, I just had to share!!!!!!!!
pp....
DO not archive
Message 17
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| Subject: | Re: Fuselage Tube Alignment |
--> Kolb-List message posted by: CaptainRon <CaptainRon@theriver.com>
1/25/03 13:47John Hauck
> We need to be extremely careful handing out
> information that deviates from the builder's
> instruction manual.
===========================
Since we are neat picking. :-)
I consider forcing one bolt out with another bolt to be a worse choice than
slightly boring out the cage chrom molly tube which is what I believe is the
problem. Here is why, by forcing the bolt through the holes the way you are
suggesting, you are introducing permanent stress point somewhere, most
likely right against the aluminium tube itself where the bolt is obviously
forcing itself through the tube. Will it crack there?? possibly,, depending
on the mis-alignment and the local area vibrations. I need to add that I
read his message differently than you have. You think its not going clear
through the tube, where I understood it to go clear through the tube but not
through the cage. If you would have read my message a bit more carefully you
would have understood that.
Again I stand by my advice for the problem as I understand it, and again
without being critical I may add that building a number of aircraft and all
of them potentially wrong, is not a qualification to offer advice based on
that. :-)
================
JH>>If you look back on the history of Kolb crashes
where a tail boom fails during the crash, it
always fails at the rear end of the "H" brace.
=================
Indeed, which supports my point that the H bracket bolt carry through area
is over built by a substantial margin. Also keep in mind that the load on
the Tube H bracket area is shared by both the Bolt and the inner ring, where
the bolt to a large extent is a pivot point for the load carried by the
inner ring. In other words the weakest area is exactly where you noticed it
is, and it will remain so even after you bore out the Chrome Molly down tube
a bit.
Build it the way you wanna... John.
Message 18
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| Subject: | Re: Honda's for aircraft message of Fri, 24 Jan |
2003 23:56:08 -0800
--> Kolb-List message posted by: "Don Gherardini" <donghe@one-eleven.net>
Mike,
I am of course talking about Honda 4 strokes...but generally my post was to
respond to what causes rod bearing failures in IC engines. I believe that
the problems we encounter in those typical vent fan installations might be
similiar however to aircraft installations. Also I should qualify my
predjudices. We design our engines to last for 2000 hours at 90% duty cycle.
(thats what the market demands) I swallow hard when I see all of my flying
friends, and myself, forced to overload the design parameters of the engines
we use and get lucky if we got more than 300 hours out of an engine on an
light aircraft.
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.
I make no claims as to being any kind of expert on a rotax or Hirth or 2si
or whatever , and have little personal expierience here.
I do observe a sport however (and also participate) in which i see engines
failing right and left at 200 to 300 hours due to crank and bearing related
failures, and I am only offering my thoughts and expieriences for all to
mull over, You see when one of my customers has bottom end failure at these
low times he most likely will never buy another one just like it...because
he has many other choices, but an Ultralighter has few, and most likely must
replace with another just like the one that just failed. (this probably
bothers me the most of all!)
And Rotax mandating a crank replacement at 250 hours or something like
that?...jeez, in my biz...we would be laughed right out of the country!
About the only thing I know for sure, is why thay make this
recommendation....They, like we at Honda, are very aware of the propeller
and its load impulses and the effect on a crankshaft these vibes have.
Now..on the trash pump and generator comparison....it is not valid. the
occasional rock or other sudden stoppage of a trash pump, if not bad enuf to
snap a crank or a rod...is much different than the air pressure differential
that happens every rpm 2,..3 , or 4 times per rev . this constant pounding
is usually what makes a well lubed rod bearing fail IF heat is NOT
determined to be the culprit.
However you bring to mind the application we HATE the most in my biz....the
high pressure washer!
this application has the Highest crankshaft failure rate in my
industry...regardless of engine manufacture!
It is commonly known in my biz that whatever engine you put on a pressure
washer....it will bring you the highest frequency of warranty claims.
Why?....because of the direct drive hookup, and the pulsating load of a high
pressure piston pump. These constant pulses cause more havoc than anything
else . from snapping of work-hardened, vibration -weakened cranks to
hammered rod bearing failures and similiar damage scenarios, even when
Love-Joy style(torsional vibe absorbing) connections are used.....again,
reminds me of the forces encountered on a prop/pusher airplane engine crank.
Any lash by the way in the gearbox would not be the source of the
problem...just a magnifying component.
Steve, I am not trying give you an analysis of your failure, only describing
some expieriences that might possibly give you some insight , because I, as
I suspect you, dont buy that preservation procedure stuff one bit!
You mentioned that you had a C-box with the built-in torsion coupler. thats
good, but it only means that if the problem was infact determined to be the
above "speculation"...then it most likely would have only failed sooner
without it. I have pressure washer manufacturer customers that install over
size torsional isolating couplers to battle this constant problem....it
helps...but seldom eliminates.
Mike...quote...."sounds like Honda is under engineered in this
area"........grrrrrrrrrrrrrrr, you trying to get me going pard ??????/
LoL.....hehe
its cold in Illinois men, cant work on my plane, and I only offer thoughts
here....no solutions!
Don Gherardini
FireFly 098
Message 19
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| Subject: | Re: Honda's for aircraft message of Fri, 24 Jan |
2003 23:56:08 -0800
--> Kolb-List message posted by: "Richard Harris" <rharris@magnolia-net.com>
Don, It is fruitless to try to defend your Honda ( or any other ) engines
here on the list, because everyone believes that the engine they are using
at the present is the only one that is worth a damn. Having said that, I
truly do believe Honda could make a very good engine for our aircraft, if
they just would. .. Its called liability and they are not willing to take
the chance.... They did in 41 and lost..
Richard Harris
MK3 N912RH
Lewisville, Arkansas
> --> Kolb-List message posted by: "Don Gherardini" <donghe@one-eleven.net>
>
> Mike,
> I am of course talking about Honda 4 strokes...but generally my post was
to
> respond to what causes rod bearing failures in IC engines. I believe that
> the problems we encounter in those typical vent fan installations might be
> similiar however to aircraft installations. Also I should qualify my
> predjudices. We design our engines to last for 2000 hours at 90% duty
cycle.
> (thats what the market demands) I swallow hard when I see all of my
flying
> friends, and myself, forced to overload the design parameters of the
engines
> we use and get lucky if we got more than 300 hours out of an engine on an
> light aircraft.
> 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.
>
> I make no claims as to being any kind of expert on a rotax or Hirth or 2si
> or whatever , and have little personal expierience here.
> I do observe a sport however (and also participate) in which i see engines
> failing right and left at 200 to 300 hours due to crank and bearing
related
> failures, and I am only offering my thoughts and expieriences for all to
> mull over, You see when one of my customers has bottom end failure at
these
> low times he most likely will never buy another one just like it...because
> he has many other choices, but an Ultralighter has few, and most likely
must
> replace with another just like the one that just failed. (this probably
> bothers me the most of all!)
> And Rotax mandating a crank replacement at 250 hours or something like
> that?...jeez, in my biz...we would be laughed right out of the country!
> About the only thing I know for sure, is why thay make this
> recommendation....They, like we at Honda, are very aware of the propeller
> and its load impulses and the effect on a crankshaft these vibes have.
> Now..on the trash pump and generator comparison....it is not valid. the
> occasional rock or other sudden stoppage of a trash pump, if not bad enuf
to
> snap a crank or a rod...is much different than the air pressure
differential
> that happens every rpm 2,..3 , or 4 times per rev . this constant
pounding
> is usually what makes a well lubed rod bearing fail IF heat is NOT
> determined to be the culprit.
>
> However you bring to mind the application we HATE the most in my
biz....the
> high pressure washer!
> this application has the Highest crankshaft failure rate in my
> industry...regardless of engine manufacture!
> It is commonly known in my biz that whatever engine you put on a pressure
> washer....it will bring you the highest frequency of warranty claims.
> Why?....because of the direct drive hookup, and the pulsating load of a
high
> pressure piston pump. These constant pulses cause more havoc than anything
> else . from snapping of work-hardened, vibration -weakened cranks to
> hammered rod bearing failures and similiar damage scenarios, even when
> Love-Joy style(torsional vibe absorbing) connections are used.....again,
> reminds me of the forces encountered on a prop/pusher airplane engine
crank.
> Any lash by the way in the gearbox would not be the source of the
> problem...just a magnifying component.
>
> Steve, I am not trying give you an analysis of your failure, only
describing
> some expieriences that might possibly give you some insight , because I,
as
> I suspect you, dont buy that preservation procedure stuff one bit!
> You mentioned that you had a C-box with the built-in torsion coupler.
thats
> good, but it only means that if the problem was infact determined to be
the
> above "speculation"...then it most likely would have only failed sooner
> without it. I have pressure washer manufacturer customers that install
over
> size torsional isolating couplers to battle this constant problem....it
> helps...but seldom eliminates.
>
> Mike...quote...."sounds like Honda is under engineered in this
> area"........grrrrrrrrrrrrrrr, you trying to get me going pard ??????/
>
> LoL.....hehe
>
> its cold in Illinois men, cant work on my plane, and I only offer thoughts
> here....no solutions!
>
> Don Gherardini
> FireFly 098
>
>
Message 20
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--> Kolb-List message posted by: <rowedl@highstream.net>
Hey,
My workshop got up to 35 degrees today, no coveralls required, must be a
nationwide warming trend.
Denny
----- Original Message -----
From: Larry Bourne <biglar@gogittum.com>
Subject: Kolb-List: Weather
> --> Kolb-List message posted by: "Larry Bourne" <biglar@gogittum.com>
>
> OH DEAR ! ! ! 83 deg in Palm Springs today, and my swamp cooler isn't
working right. Got stuffy and warm in here, so had to fire up the A/C.
Hate ta waste all that electicity at this time of year, ya know. :-) :-)
Lar. Do not Archive.
>
> Larry Bourne
> Palm Springs, CA
> Kolb Mk III - Vamoose
> www.gogittum.com
>
>
Message 21
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| Subject: | 110% duty cycle? |
--> 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 22
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| Subject: | Re: 110% duty cycle? |
--> Kolb-List message posted by: WhiskeyVictor36@aol.com
In a message dated 01/25/2003 11:34:49 PM Eastern Standard Time,
rwpike@charter.net writes:
> 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)
>
Me not a rocket scientist, so more food for thoughts. You get 6500 rpm at
wot level flight. During climb you get 6000~6200 rpm because of prop load on
engine. If reduce throttle, but maintain previous climb speed, load not
reduced. Seems engine would still be in %110 range.
What if you lower the nose, climb at higher air speed, maybe returning to
6300~6400 rpm. Would this lower the duty cycle to say 100% or so?
Bill Varnes
Kolb FireStar
Audubon NJ
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