Today's Message Index:
----------------------
1. 12:48 AM - Re: Thrust Line (David L. Bigelow)
2. 05:51 AM - looking for 912 (lucien stavenhagen)
3. 10:09 AM - monument valley (Erich_Weaver@URSCorp.com)
4. 10:52 AM - Re: monument valley (Robert Laird)
5. 11:03 AM - Re: monument valley (John Hauck)
6. 12:52 PM - Re: ROTAX 582 JET NEEDLE ADJUSTMENT/RADIATOR TIPS/ELECTRIC VEST TESTI (Jim Ballenger)
7. 01:13 PM - Re: ROTAX 582 JET NEEDLE ADJUSTMENT/RADIATOR TIPS/ELECTRIC VEST TESTI (John Hauck)
8. 01:30 PM - Re: ROTAX 582 JET NEEDLE ADJUSTMENT/RADIATOR TIPS/ELECTRIC VEST TESTI (lucien stavenhagen)
9. 01:34 PM - Re: Re: Thrust Line (Michael Bigelow)
10. 02:05 PM - Inspection Repairman Cert (Robert Mason)
11. 02:16 PM - Re: Re: Thrust Line (Christopher Armstrong)
12. 02:57 PM - Re: Re: Thrust Line (Richard & Martha Neilsen)
13. 03:16 PM - Re: Inspection Repairman Cert (John Hauck)
14. 04:04 PM - Re: Inspection Repairman Cert (Dave & Eve Pelletier)
15. 04:09 PM - Thrust Line (Christopher Armstrong)
16. 04:56 PM - Re: Inspection Repairman Cert (Robert Mason)
17. 06:18 PM - Re: ROTAX 582 JET NEEDLE ADJUSTMENT (Jim Baker)
18. 06:57 PM - Re: Thrust line change (Ron Hoyt)
19. 07:26 PM - Re: Re: Thrust line change (John Hauck)
Message 1
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--> Kolb-List message posted by: "David L. Bigelow" <dlbigelow@verizon.net>
The pitching moment due to thrust is dependent on the distance the thrust line
is from the center of drag - not the CG. If the thrust line is right through
the center of drag, there will be no pitch moment up or down.
Can't show it here, but a vector diagram of an aircraft in equilibrium will illustrate
this fact. The center of drag of a high wing aircraft like a Kolb is
somewhere below and behind the center of lift of the wing. Because of the tail
boom, you cannot get the thrust line low enough on a Kolb to avoid a nose down
pitching moment when thrust is applied. Changing the thrust vector direction
by tilting the engine up or down will affect the equation somewhat, but not
enough to compensate for the loss of efficiency.
Best angle of the thrust line is about 6 degrees down from the chord of the wing.
This allows the aircraft to have all the thrust vector pointed parallel to
the airflow at a normal flying angle of attack of the aircraft, which is the
most efficient.
Dave Bigelow
Kamuela, Hawaii
FS2, DCDI 503
Message 2
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--> Kolb-List message posted by: "lucien stavenhagen" <lstavenhagen@hotmail.com>
Hi all,
Speaking of 912's... I'm starting to put feelers out for a low to mid-time
912 in good shape. The kolbra is looking like the #1 contender for my next
plane, so I'm looking for a 912 to power it. A new one is a little out of
reach at the moment, so a good used motor is what I'm looking for right now.
If anyone knows of a good deal, let me know....
Thanks,
LS
N646F
Message 3
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12/12/2005 01:09:15 PM
--> Kolb-List message posted by: Erich_Weaver@URSCorp.com
Hey gang
I havent been paying close attention lately, so not sure if the word has
gotten out, but I recently sold my Mrk III and trailer to Robert Laird. I
have been working on an RV-7A project for the past year, and decided that
sooner or later I was going to have to give up my first love. Still a bit
sad about it, but will soon be receiving the engine for the RV, and am
getting very excited about that.
For all those who havent been, Monument Valley is a fantastic place to
fly, and Im proud to count myself as one of the original founders of what
now appears to be an annual tradition. Because of me, we all now know that
fly-bys of the restaurant balcony are frowned on by management! I hope to
see you all there in May 2006, but its going to be a bit to soon to take
the RV, so I'll be ground bound. I believe Robert is excited about MV as
well, so I expect you will be seeing him there in the future with a
familiar looking plane, although Im not sure about his 2006 plans
Best regards to all my Kolb friends
Erich Weaver
Message 4
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| Subject: | Re: monument valley |
--> Kolb-List message posted by: Robert Laird <rlaird@cavediver.com>
I'd like to thank Erich for his offering up his "baby" to me, and very
glad to finally own a Kolb. I took it for a romp around the pattern
on Saturday and, compared to what I was flying before, the Kolb is
nimble and quick... a real joy to fly.
As for Monument Valley, it's my _plan_ to be there, but there are two
problems: one is, my son will still be in school that weekend, so if
I make it, it would have to be solo; and, two, I've just started a new
job and it's still up in the air (no pun intended) whether I'll be
able to get the time off for that period.
But, if the gods favor idiots and fools, then I'll be there for certain! <g>
-- Robert
On 12/12/05, Erich_Weaver@urscorp.com <Erich_Weaver@urscorp.com> wrote:
> --> Kolb-List message posted by: Erich_Weaver@URSCorp.com
>
> Hey gang
>
> I havent been paying close attention lately, so not sure if the word has
> gotten out, but I recently sold my Mrk III and trailer to Robert Laird. I
> have been working on an RV-7A project for the past year, and decided that
> sooner or later I was going to have to give up my first love. Still a bit
> sad about it, but will soon be receiving the engine for the RV, and am
> getting very excited about that.
>
> For all those who havent been, Monument Valley is a fantastic place to
> fly, and Im proud to count myself as one of the original founders of what
> now appears to be an annual tradition. Because of me, we all now know that
> fly-bys of the restaurant balcony are frowned on by management! I hope to
> see you all there in May 2006, but its going to be a bit to soon to take
> the RV, so I'll be ground bound. I believe Robert is excited about MV as
> well, so I expect you will be seeing him there in the future with a
> familiar looking plane, although Im not sure about his 2006 plans
>
> Best regards to all my Kolb friends
>
> Erich Weaver
>
>
Message 5
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| Subject: | Re: monument valley |
--> Kolb-List message posted by: "John Hauck" <jhauck@elmore.rr.com>
| Because of me, we all now know that
| fly-bys of the restaurant balcony are frowned on by management! I
hope to
| see you all there in May 2006, but its going to be a bit to soon to
take
| the RV, so I'll be ground bound. |
| Erich Weaver
Hi Erich/Gang:
Good to hear from you.
Yes, you are the "fly by man". However, I thought it looked cool.
Too bad the management and all the nerds in the lodge and restaurant
did not agree with me. hehehe
Looking forward to seeing you and your family next May, with or
without the RV.
john h
DO NOT ARCHIVE
Message 6
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| Subject: | Re: ROTAX 582 JET NEEDLE ADJUSTMENT/RADIATOR TIPS/ELECTRIC |
VEST TESTI
--> Kolb-List message posted by: "Jim Ballenger" <ulpilot@cavtel.net>
LS
Very informative. Thanks for the insight and explanation of the piston
skirt/rotary valve issue. It kinda makes ense to me.
Jim
----- Original Message -----
From: "lucien stavenhagen" <lstavenhagen@hotmail.com>
Subject: Re: Kolb-List: ROTAX 582 JET NEEDLE ADJUSTMENT/RADIATOR
TIPS/ELECTRIC VEST TESTI
> --> Kolb-List message posted by: "lucien stavenhagen"
> <lstavenhagen@hotmail.com>
>
> Hey all,
>
> This is where the skirt of the piston acts as the intake valve. On the
> aircooled rotaxen, the intake ports are lower in the sleeve (and on the
> other side) than the exhaust ports. As the piston goes up, the skirt
> clears
> the port, causing an opening into the crankcase - the vacuum from the
> upgoing piston pulls the air/fuel mixture in in the familiar way. On the
> power stroke, the skirt blocks the port off closing it, allowing crankcase
> pressure to build up for the exhaust stroke....
>
> The 582 uses a mechanically driven rotary valve to control the intake,
> which
> involves some extra machinery and complexity.
>
> The advantage of the rotary valve, though, is very smooth running and
> broad
> powerband. Sure enough, the 582 runs like a swiss watch... The piston
> skirt
> induction motors are much simpler, but they tend to be peakier and behave
> more "2-strokey"....
>
> I still far prefer the simplicity of piston skirt induction.......
>
> There are other induction methods for 2-strokes besides these, such as
> reed
> valves and crankshaft induction (these are common on R/C 2-stroke
> motors)...
>
> LS
> N646F
>>Morning LS/Gang:
>>
>>Could you explain "piston-skirt indiction" please.
>>
>>Thanks,
>>
>>john h
>>
>>
>
>
>
Message 7
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| Subject: | Re: ROTAX 582 JET NEEDLE ADJUSTMENT/RADIATOR TIPS/ELECTRIC |
VEST TESTI
--> Kolb-List message posted by: "John Hauck" <jhauck@elmore.rr.com>
| piston skirt/rotary valve issue.
| Jim
|
Jim B/LS/Gang:
Correct me if I am wrong, please. Isn't this system more commonly
called a "piston/port" system? The system used on the 503 and others,
other than the 582?
john h
MKIII
Message 8
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| Subject: | Re: ROTAX 582 JET NEEDLE ADJUSTMENT/RADIATOR TIPS/ELECTRIC |
VEST TESTI
--> Kolb-List message posted by: "lucien stavenhagen" <lstavenhagen@hotmail.com>
>Jim B/LS/Gang:
>
>Correct me if I am wrong, please. Isn't this system more commonly
>called a "piston/port" system? The system used on the 503 and others,
>other than the 582?
Nope, you're not wrong, I've heard piston ported as well......
LS
N646F
>john h
>MKIII
>
>
Message 9
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| Subject: | Re: RE: Thrust Line |
--> Kolb-List message posted by: "Michael Bigelow" <orcabonita@hotmail.com>
As I am building a Kolb I have been watching the thread about pitch down
with power with great interest. Changing the thrust line angle works very
well on a standard airplane where the engine is mounted in the nose, and
also works well on a Jet airplane where the engines are mounted on the tail.
This is because in these two cases the engine is far enough foward or
behind the CG, that the angle of the thrust has an effect of pitching the
airplane either up or down. For example, with the engine in the nose, down
thrust will pull the nose downward, and pitch the plane down. An engine in
the tail with downthrust will push the tail of the airplane up cuasing the
plane to pitch down.
In the Kolb, the prop is very close to the CG of the airplane as far as
pitch goes. Pointing the prop up (higher thrust angle) and having the
engine push down right near the CG will have no noticable effect on pitch.
Bottom line is, if you want to help pitch the airplane by using thrust
angle, it needs to be done much further foward or further aft of the PITCH
CG. Its just not going to happen on a Kolb.
With the engine and prop mounted far above the center of drag, the kolb will
always pitch down with power, there is just no getting around it. Best
thing is to lower the engine and prop as much as possible, without striking
the boom.
Michael Bigelow
Message 10
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| Subject: | Inspection Repairman Cert |
--> Kolb-List message posted by: Robert Mason <masonclan@sbcglobal.net>
I just got back this weekend from the 16 Hr Inspection Repairman class and
received a temporary repairman certificate from my Local FSDO today.
I will be setting up a time for my ELSA airworthiness inspection. Hope to be
flying by January
Do not archive
Robert Mason
Mark 3X 582
Simi Valley
Message 11
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--> Kolb-List message posted by: "Christopher Armstrong" <tophera@centurytel.net>
>>>The pitching moment due to thrust is dependent on the distance the thrust
>>>line is from the center of drag - not the CG. If the thrust line is
>>>right through the center of drag, there will be no pitch moment up or
>>>down.
No, sounds good, even sort of works in some cases, but it is not correct.
There is a contribution to pitching moment from drag around the cg and a
contribution to pitching moment from thrust around the cg and a pitching
moment due to lift about the cg and many more. The total of all these
contributions is the resultant pitching moment.
If you sum pitching moment about some point other then the cg the one that
would be used typically is the aerodynamic center.(There are different
centers of lift and drag for each angle of attack so that isn't really a
good choice.) At the Aerodynamic center pitching moment due to primary
aerodynamics is constant with angle of attack, so all changes in pitching
moment are due to weight and thrust. The reason we usually sum pitching
moment about the cg (besides the fact that that is the point about which the
aircraft will rotate) is that then there is no pitching moment due to
weight, which is really important because weight is always pointed at the
earth, not fixed to the aircraft like the other forces. So to sum at the AC
you have to know not just your angle of attack but also your angle of
incidence, so you can get your components of weight added in the right
direction, and with the right moment arms which will change for each angle
of incidence.
Your contention that if the thrust goes through the drag center you get no
pitching moment only works if thrust is equal to drag, which is true in
steady flight. But when you change thrust, which is when we notice these
things, you get more or less thrust then drag and you get a pitching moment
change.
An extreme example of this is a powered parachute, where the thrust is
nearly through the cg, and the center of drag is about 30 feet higher. When
you apply power the trike carriage does not rotate because the thrust is
acting through the cg of the craft, about which all free bodies rotate. But
the drag center is way up there so the craft pitches up due to a pitching
moment from drag since it has a large moment arm to the cg, not due to
thrust which has zero moment arm and can not impart a pitching moment.
If you put the thrust way up there with the parasail, but keep the cg down
low now you would have a large pitching moment due to thrust as well as drag
and if thrust is equal to drag they will cancel each other out (which is
what you were referring to above.) But when they are different then you
will still get a really big pitching moment due to the large moment arm to
the cg, and when they are different is when we notice the problem.
So to get it right we try to have the center of drag and thrust near the
vertical cg, which puts them near each other as well. Since that is not the
case on a Kolb you will get a big pitching moment delta whenever thrust
times its moment arm to the cg is not nearly equal to drag times it's moment
arm to the cg. You are summing the moments not the forces, and you want the
sum to be zero, so what matters is the total of all the forces times their
distances to some reference point. The reference that is the best to use is
the cg since that allows you to ignore the only variable direction force you
have, weight. When the plane does pitch it will pitch about the cg, so to
calculate how much it rotates we use the moment about the cg and the moment
of inertia about the cg to calculate the acceleration about the cg.
Topher
Do Not Archive (it is already in there 5 times)
Message 12
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| Subject: | Re: RE: Thrust Line |
--> Kolb-List message posted by: "Richard & Martha Neilsen" <NeilsenRM05@comcast.net>
Topher/All
Thanks I always get an education from your posts. At some point I'm going to
try some flow fences on my MKIIIc like you suggested some time ago but for
now....
The only clarification I would like to address is that the CG is only a
factor when you are accelerating or decelerating. If you are in a cruise
mode of flight you only have to get your center of thrust at your center of
drag to have no pitching moment.
Do not archive
Rick Neilsen
Redrive VW powered MKIIIc
----- Original Message -----
From: "Christopher Armstrong" <tophera@centurytel.net>
Subject: RE: Kolb-List: RE: Thrust Line
> --> Kolb-List message posted by: "Christopher Armstrong"
> <tophera@centurytel.net>
>
>
>>>>The pitching moment due to thrust is dependent on the distance the
>>>>thrust
>>>>line is from the center of drag - not the CG. If the thrust line is
>>>>right through the center of drag, there will be no pitch moment up or
>>>>down.
>
> No, sounds good, even sort of works in some cases, but it is not correct.
>
> There is a contribution to pitching moment from drag around the cg and a
> contribution to pitching moment from thrust around the cg and a pitching
> moment due to lift about the cg and many more. The total of all these
> contributions is the resultant pitching moment.
>
> If you sum pitching moment about some point other then the cg the one that
> would be used typically is the aerodynamic center.(There are different
> centers of lift and drag for each angle of attack so that isn't really a
> good choice.) At the Aerodynamic center pitching moment due to primary
> aerodynamics is constant with angle of attack, so all changes in pitching
> moment are due to weight and thrust. The reason we usually sum pitching
> moment about the cg (besides the fact that that is the point about which
> the
> aircraft will rotate) is that then there is no pitching moment due to
> weight, which is really important because weight is always pointed at the
> earth, not fixed to the aircraft like the other forces. So to sum at the
> AC
> you have to know not just your angle of attack but also your angle of
> incidence, so you can get your components of weight added in the right
> direction, and with the right moment arms which will change for each angle
> of incidence.
>
> Your contention that if the thrust goes through the drag center you get no
> pitching moment only works if thrust is equal to drag, which is true in
> steady flight. But when you change thrust, which is when we notice these
> things, you get more or less thrust then drag and you get a pitching
> moment
> change.
Message 13
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| Subject: | Re: Inspection Repairman Cert |
--> Kolb-List message posted by: "John Hauck" <jhauck@elmore.rr.com>
Hope to be
| flying by January
|
| Robert Mason
Bob M/Gang:
That is great news.
Be looking for you at MV next year, with airplane. ;-)
Good luck on your inspection and first flight.
john h
DO NOT ARCHIVE
Message 14
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| Subject: | Re: Inspection Repairman Cert |
--> Kolb-List message posted by: "Dave & Eve Pelletier" <pelletier@cableone.net>
Robert,
Cnogratulations! Where did you take the class - Rainbow Aviation? And
can you give us a rundown on what was covered/
Thanks,
AzDave
Do Not Archive
> I just got back this weekend from the 16 Hr Inspection Repairman class and
> received a temporary repairman certificate from my Local FSDO today.
>
>
>
Message 15
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--> Kolb-List message posted by: "Christopher Armstrong" <tophera@centurytel.net>
That is what I said, probably not very clearly though! ;-)
It matters when you are accelerating or whenever thrust does not equal drag
and you are not accelerating.... whenever that might be...
Christopher Armstrong
-----Original Message-----
From: owner-kolb-list-server@matronics.com
[mailto:owner-kolb-list-server@matronics.com] On Behalf Of Richard & Martha
Neilsen
Subject: Re: Kolb-List: RE: Thrust Line
--> Kolb-List message posted by: "Richard & Martha Neilsen"
<NeilsenRM05@comcast.net>
Topher/All
Thanks I always get an education from your posts. At some point I'm going to
try some flow fences on my MKIIIc like you suggested some time ago but for
now....
The only clarification I would like to address is that the CG is only a
factor when you are accelerating or decelerating. If you are in a cruise
mode of flight you only have to get your center of thrust at your center of
drag to have no pitching moment.
Do not archive
Rick Neilsen
Redrive VW powered MKIIIc
Message 16
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| Subject: | Re: Inspection Repairman Cert |
--> Kolb-List message posted by: Robert Mason <masonclan@sbcglobal.net>
Dave,
I did take the class from Carol and Brian at Rainbow Aviation, really
good people, we covered flight theory, aircraft systems, inspection
procedures, engine and prop inspections, regulations, maintenance
record keeping and hardware. It was lecture and hands on. 50 question
test at the end of the course.
Robert
--- Dave & Eve Pelletier <pelletier@cableone.net> wrote:
> --> Kolb-List message posted by: "Dave & Eve Pelletier"
> <pelletier@cableone.net>
>
> Robert,
>
> Cnogratulations! Where did you take the class - Rainbow
> Aviation? And
> can you give us a rundown on what was covered/
>
> Thanks,
>
> AzDave
>
> Do Not Archive
>
>
> > I just got back this weekend from the 16 Hr Inspection Repairman
> class and
> > received a temporary repairman certificate from my Local FSDO
> today.
> >
> >
> >
>
>
>
>
>
>
>
Message 17
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| Subject: | Re: ROTAX 582 JET NEEDLE ADJUSTMENT |
--> Kolb-List message posted by: "Jim Baker" <jlbaker@telepath.com>
> Thanks for the insight and explanation of the
> piston skirt/rotary valve issue. It kinda makes ense to me.
For anyone really serious about understanding the two stroke
engine.....
http://kawtriple.com/mraxl/jennings.htm
I've got a hard copy of the book referenced by the link above.
Wouldn't part wth it for love nor money (out of print and signed by
Jennings).
Jim Baker
580.788.2779
'71 SV, 492TC
Elmore City, OK
Message 18
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| Subject: | Re: Thrust line change |
--> Kolb-List message posted by: Ron Hoyt <rrhoyt@ieee.org>
I have been reading the thread with great interest since my mark III
requires a large rudder tab that I dislike. I have been mulling over
the impact of rotating the 912 a couple of degrees in azimuth to
mitigate the yaw that the rudder tab corrects. I tried flexing the
vertical stabilizer to effect a change but it was not noticeable in
flight. Christopher's line of reasoning implies that the moment arm
is small and a substantive change is not likely. Is there any
experience out there with this trimming.
Ron
Kolb Mark III C
N232S
Message 19
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| Subject: | Re: Thrust line change |
--> Kolb-List message posted by: "John Hauck" <jhauck@elmore.rr.com>
| experience out there with this trimming.
|
| Ron
Ron H/Gang:
Yes, a little. I have been dabbling with Kolbs for 21 years, and my
MKIII for the last 15 years.
Did the engine rotation thing, left and right, up and down, on my FS,
back in the mid 80's. Did the same thing on the MKIII with the
engine.
Tried different settings for the leading edge of the upper vertical
stabilizer, offset as much as 1 3/8" to the left, with little positive
effect. Wasn't worth the effort. Put it back where it belonged in
the center.
During construction I knew I was going to have to do something about
the pitch down caused by power, and the tendancy to roll left when
flying left seat solo. To solve those problems I fly right seat and
made up some adjustable horizontal stabilizer forward mounts.
Experiemented lowering at different levels until I found the sweet
spot for the airplane and me. TNK now has these mounts available, I
have been told.
Adverse yaw is caused by the way the prop wash hits the tail section.
I flew for nearly a 1,000 hours 1/2 ball out of trim with a small trim
tab, one rudder rib bay width long. Now I have one twice as long and
I fly trimmed in pitch. No noticeable difference in performance
between then and now. The old MKIII is happy flying in or out of yaw
trim. Now I don't have to push a lot of right pedal to swing it back
into trim. BTW, a lot of folks on the Kolb List refer to the
"slip/skid" indicator as a turn and bank indicator. Don't think so.
It does three things. Tells me when I am skidding, slipping, and when
I am in trim. If I want to check its accuracy, I can stick a yaw
string on the lower center of the windshield or top of the nose cone
to see if they agree.
Nothing wrong with the big trim tab or a lot of forced trim to take
the forward stick pressure off your hand and arm.
This is the nature of the MKIII. Most of the things folks are
experiementing with now, trying to improve on Kolbs, has already been
done. With the exception of seriously cleaning up aerodynamically a
couple areas of my old MKIII, she is going to stay as she is. With
nearly 2,500 hours flying her from the right seat (all those hours on
her are mine), I pretty much accept the way she is. I'm happy with
her. That is why I still fly her.
Not really concerned too much on why she does what she does. All I
know is she does a good job for me.
It is still fun trying to improve your own airplane, expecially is it
is new without a whole bunch of years and hours on it. I know. I
have been there. It was a lot of fun, frustrating at times, but I'd
probably do it again if I could.
Take care,
john h
MKIII, 912ULS
hauck's holler, alabama
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