KR> Jabiru's in Kr2s.

[Mark Langford]

Colin Hales wrote:

> I haven't got flaps or a speed brake. You don't need
> them. People keep saying that "They float!" How? Its got tiny wings!
> The problem mostly seems to be that people need a high throttle
> position to keep their poorly idling engines going on the ground at
> say, 700 rpm. This unfortunately turns into about 1,400 rpm in the
> air. No wonder it floats, thats still about 1/4 throttle. If you
> remove the idle stop for your engine all together, if you close the
> throttle completely, it now acts like a exhaust brake. The engine
> will never stop in the air, it just windmills at 500 rpm causing
> massive drag and the aircraft stops and falls out the sky. When you
> land and the idle gets lower as they airspeed decreases, just crack a
> little throttle back on.

I have several problems with the above paragraph.  One is that even if 
your engine is switched off and the prop stopped (I've never seen mine 
windmill, either the Corvair or the VW), a drag brake is useful.  If 
nothing else, the brake acts as another control system to provide more 
flexibility in landing, whether "deadstick" or normal.  It's another 
tool in the box, just like slipping.  Another benefit is added drag 
behind the CG, which helps to stabilize the airplane while landing. 
Nothing like a drag chute, but a small step in the right direction.

As for "poor idling at 700 rpm", most aircraft makers, and indeed auto 
makers, probably wish they could make their engines idle reliably and 
smoothly at 700 rpm under all temperature conditions.  Most everything 
I've driven is stabilized from the factory at something like 950 rpm. 
The best I can do with N891JF's engine is idling at about 800 RPM, and 
the Corvair is similar.  This puts me at about 1050 to 1100 RPM on short 
final.

I've never seen a carburetor that would run 700 rpm while open at 25% 
throttle.  Most carburetors (or what passes for a carburetor in the case 
of the POSA) either have a dedicated idle circuit and require no 
throttle opening at all, or have a slight opening that might be 5%, 
rather than 25% open, when running at idle.  25% throttle might be 1800 
rpm, but not 700 rpm, at least not on a "normal" engine.

You have far bigger gonads than I do if you fly with no throttle stop 
and routinely let the engine almost die on every landing. Fiddling with 
the throttle to keep it running on rollout seems another distraction 
that I don't need.  I pull the throttle back to idle when I'm abeam the 
numbers and leave it there unless I need power to make the runway (which 
is rare...although I may slip it to kill extra altitude).  I guess I 
can't argue with your success, but it's contrary to everything I know 
about how to drive cars or fly airplanes.   It's one less thing to fool 
around with while landing.  That cure seems worse than the disease.

I guess I can't say I've tried it, but I have tried belly boards (both 
before and after), and I do highly recommend them...

-- 
Mark Langford
ML at N56ML.com
http://www.n56ml.com

KR> Jabiru

[Tony King]

Just one correction - CASA has proposed the restrictions, they haven't
introduced them yet and hopefully they never will.  Just the proposal alone
has been damaging enough, and the way CASA has gone about addressing this
problem (if indeed there is a problem - which they've acknowledged they
don't actually know) is a classic example of a bureaucracy with too much
power and too little accountability.  Unlike the FAA, the promotion of
aviation is not part of CASA's charter.  Many people joke that CASA regards
only aircraft that never fly as being safe enough, but they could actually
implement such a policy (i.e. ground everything) without violating their
charter.

TK

On 30 November 2014 at 05:39, Mike Stirewalt via KRnet  wrote:

> Someone commented recently on the forum that CASA (Australian FAA) has
> limited Jabiru-powered aircraft to day VFR.  Most Jabiru powered planes
> are already used in that environment as trainers or light sport designs
> but for those who want to use their Jabiru-powered airplane as a normal
> airplane - tough luck if you live in Australia.  CASA's new restrictions
> include no carrying of passengers, no solo students, and no flying over
> populous areas.
>
> http://www.casa.gov.au/wcmswr/_assets/main/newrules/download/spc-cd1425ss
> .pdf
>
> "Seems like the major problems are still the through bolts (rolled vs cut
> threads), valve guides and crankcase fretting."  (from pprune.org forum)
>
> Apparently rings & pistons & exhaust valves are frequent culprits with
> Jab engine failures.
>
> Paul Hanson with my local Chapter 14 finally sold his Wittman Tailwind
> with a Jab 3300 after continually having valve seats come out.  The buyer
> is putting in another, (different make) engine.
>
> It would be interesting to talk to Richard Shirley about his 3300.
>
> Many flight schools who use Jabirus run their engines, at least some of
> them, all the way to TBO.  And Colin has flown lots of miles with his
> 2200 so he would be another person with whom to discuss his thoughts on
> the subject.
>
> What is "crankcase fretting?"  I'm having trouble visualizing this but
> this is when the crankcase "swells" and squeezes the crankcase journals
> so tightly that the engine won't turn after shutdown until it has had a
> chance to cool.  Naturally something like this, besides causing
> horrendous bearing wear, eventually leads to a cracked crankcase.  It
> happens on some runs of the 4-stroke Rotax engine too I'm reading.
>
> Dealing with maintenance issues like these on both the Jabiru and Rotax
> are amazingly expensive for new parts.  Not even on the same planet VW
> and Corvair.
>
> Mike
> KSEE
> 
> What's your flood risk?
> Find flood maps, interactive tools, FAQs, and agents in your area.
> http://thirdpartyoffers.juno.com/TGL3141/547a213db80da213c2ed1st04vuc
> ___
> Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search.
> To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org
> please see other KRnet info at http://www.krnet.org/info.html
> see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change
> options
>

KR> Jabiru's in Kr2s.

[Joe Nunley]

You mentioned that you don't have a speed break or flaps. What is your
landing distance on concrete and grass?

Joe
On Nov 30, 2014 3:27 PM, "colin hales via KRnet" 
wrote:

>
> Hi all,
> A couple of things. First, I'm too busy, articles, video editing, things
> are getting neglected, like my parents and friends. Lots to do before I
> return to America in January. My own fault so I try not to complain.
> I read a lot of the comments on Krnet.
> There seem to be a few repeating issues that I thought  would reply to.
> Engine reliability.
> Non of them are. I wouldn't expect any light aircraft engine to do more
> than 500 hours without a good look over. I looked at one of my exhaust
> valves while repairing a leaking exhaust gasket. It looked rough, hardend
> plating corroded and cracked at base at 300 hours. I replace my exhaust
> valves each 300 hours now. If you don't, they will brake, or stick or both.
> Temps are vital, it took a long time to make sure my engine doesn't even
> get hot.
> Its not really the engine or designers fault. Its operating conditions,
> operators and maintenance. I've read many of the reports of the jabiru
> engine failures and sort of knew why most of them had happened.
> Lets get real. The Jabiru engine has had next to know research or
> development. During the early days, the owners were doing it. I learnt
> quickly about 5 vital things to look after my Jabiru, by seeing what
> happened to the operating parameters, temps pressures when various
> operating conditions were applied. None of them have ever been added to any
> news letter or information advice from the manufacturer and I've given up
> telling people now. No one listens.I even was asked to write an article for
> our society about Jabiru engines. I entitled it, "Jabiru engines and what
> they won't tell you about them!" Highlighting about 10 issues, 5 I though
> vital for safe operation of the Jabiru engine. They never published it,said
> it was too inflammatory and open to the layers...
> I know people will now say that they have had thousands of trouble free
> use from their engines, well all I can say to that is that , you are either
> a diligent operator and maintainer, or you have been lucky.
> The Rotax engine had a lot more development thrown at it, and you have to
> pay for that in the cost of the thing. Get what you pay for... The Jabiru
> engine is expensive as well, that's because you are paying for a decent
> power to weight ratio. That's all.
> Its no good really. Its still too delicate. I use it though, but monitor
> it and all four egt and cht parameters rigorously and check heads and
> tappet clearances for signs of change or deformation regularly. Seems to
> keep going. But I don't like it. I would love to buy one and not have to
> think it was ever going to quit for 2,000 hours as they say, but its a
> joke... Not funny when they do break and seemingly they do. Anyway...
> Next, speed brakes. A KR needs to be light and none complicated if it is
> going to perform well. I haven't got flaps or a speed brake. You don't need
> them. People keep saying that "They float!" How? Its got tiny wings! The
> problem mostly seems to be that people need a high throttle position to
> keep their poorly idling engines going on the ground at say, 700 rpm. This
> unfortunately turns into about 1,400 rpm in the air. No wonder it floats,
> thats still about 1/4 throttle. If you remove the idle stop for your engine
> all together, if you close the throttle completely, it now acts like a
> exhaust brake. The engine will never stop in the air, it just windmills at
> 500 rpm causing massive drag and the aircraft stops and falls out the sky.
> When you land and the idle gets lower as they airspeed decreases, just
> crack a little throttle back on. So don't worry about how many holes to put
> in your speed brake, save yourself a lot of time and weight and
> complication and use the prop as a brake instead. This only works if you
> have a starter motor, I've accidentally let it stop once or twice out on
> the taxi way. But its safer too. No panic trying to find mag switches or
> trying to turn mags switch keys, if a dog runs out, as has happened to me.
> Just pull the throttle, which your hand is on anyway and it stops.
> More ways to skin a cat, which is a funny saying we have here. I'm not
> telling anyone anything or want any reply or discussion with this message.
> I'm just saying what I do and saying that if you haven't tried it, give it
> a go. If it works for you too, brill, if not well, I reckon holes add to
> drag. About 20 two inch holes should do.
> Keep an eye on those engines, if you have a worry, you are probably right
> and you should take a look, it never hurts.
> Best regards,
> Colin Hales.
> ___
> Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search.
> To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org
> please see other 

KR> Case fretting

[laser147 at juno.com]

Thank you Jeff and Mark.  I've never heard of case fretting until now and
thanks to you two anyone reading this knows what it is, what causes it,
how to prevent it and what to do about it (line bore & bottom end
re-build) if allowed to progress.   Re-torqueing my head bolts is now on
my "to do" list.   

Mike

***

Mike Stirewalt wrote:

> What is "crankcase fretting?"

One example of crankcase fretting is wear that occurs when the case 
halves that make up the "crank cradle" rub against one another, because 
operational forces momentarily (during each piston throw) relieve the 
bolt tension that normally holds the two halves tightly together. The 
displacement of the material at the joints allows the case halves to 
clamp together tighter when the engine isn't running, which has the 
effect of tightening the main bearings against the crank, in this
example.

-- 
Mark Langford
ML at N56ML.com
http://www.n56ml.com

*

The Jabiru engines mandate a pretty regular re-torquing of case bolts and
head bolts.  My take on this, which could be entirely wrong, is that
builders that want to treat their Jabiru like a Lycoming or Continental
(meaning with little maintenance other than oil changes) are the ones
that are seeing issues with case fretting.  In fact, that's exactly what
happens when the through bolts stretch and/or are allowed to run a bit
loose if one doesn't stick to the torque schedule in the maintenance
manual.  Through studs do stretch quite a bit, which is why Jabiru has a
torquing schedule in their maintenance manual.  

The center mains on the VW engines are often times fretted and narrowed. 
I have seen the same on the center mains on many air cooled engines,
including Lycoming and Continental if they aren't torqued correctly. 
That's the chief cause for DIVCO milling and line boring used cases is to
fix the narrowed center main due to case fretting from improperly torqued
through bolts.

-Jeff Scott
Los Alamos, NM



What's your flood risk?
Find flood maps, interactive tools, FAQs, and agents in your area.
http://thirdpartyoffers.juno.com/TGL3141/547b9a24871a61a241a0ast02vuc

KR> Bellybrake

[Kenneth Wiltrout]

I operate mine manually, I thought I might need to retract it fast in the event 
of a botched landing. I was going to go with a lineal actuator but I assumed I 
could bring it up quicker.


 On Sunday, November 30, 2014 8:35 AM, Kenneth Wiltrout via KRnet  wrote:


 I started with a belly board that had no holes in it and then I made one with 
holes. The brake w/holes works better. I believe that is because with out holes 
the board creates some lift.Kenny N6399U 

? ? On Sunday, November 30, 2014 8:25 AM, Dan Heath via KRnet  wrote:
? 

 It is a mystery.? Mine had no holes and performed very well.? No holes is
easier to implement, so, for me it seemed to be the most logical choice.? I
use an electric servo that I got from Steve Glover.? It has an automatic
stop at both ends of the throw.? I started out with a momentary switch so I
could put it down a little at a time.? However, found that full throw was
always what I needed, so changed it out for simplicity.? Switch down, board
down, switch up, board up.



Manual activation may be better, but it takes up precious room in the
cockpit, so I never considered that option.



See N64KR at?  http://KRBuilder.org - Then click on
the pics 



2105 KR Gathering - McMinnville, OR.? September 3 - 6 -- See U There.



Peoples Choice at 2013 - KR Gathering in Mt. Vernon, Il - MVN 

Best KR at 2013 - KR Gathering in Mt. Vernon, Il - MVN 

Best Interior at 2013 - KR Gathering in Mt. Vernon, Il - MVN 

Best Paint at 2013 - KR Gathering in Mt. Vernon, Il - MVN 

Best Firwwall Forward at 2013 - KR Gathering in Mt. Vernon, Il - MVN 



Best Interior and Panel at 2008 - KR Gathering in Mt. Vernon, Il - MVN





Daniel R. Heath - Lexington, SC





-Original Message-...Can anyone of the experienced
"bellybrakers"explane ,what kind of bellybrake are the most efficent? brake
is.

.Is it useful to make holes in the brakeshield or not ?

what is the most efficent deploying angle of the board ?

___
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? 
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KR> Bellybrake

[Kenneth Wiltrout]

I started with a belly board that had no holes in it and then I made one with 
holes. The brake w/holes works better. I believe that is because with out holes 
the board creates some lift.Kenny N6399U 

 On Sunday, November 30, 2014 8:25 AM, Dan Heath via KRnet  wrote:


 It is a mystery.? Mine had no holes and performed very well.? No holes is
easier to implement, so, for me it seemed to be the most logical choice.? I
use an electric servo that I got from Steve Glover.? It has an automatic
stop at both ends of the throw.? I started out with a momentary switch so I
could put it down a little at a time.? However, found that full throw was
always what I needed, so changed it out for simplicity.? Switch down, board
down, switch up, board up.



Manual activation may be better, but it takes up precious room in the
cockpit, so I never considered that option.



See N64KR at?  http://KRBuilder.org - Then click on
the pics 



2105 KR Gathering - McMinnville, OR.? September 3 - 6 -- See U There.



Peoples Choice at 2013 - KR Gathering in Mt. Vernon, Il - MVN 

Best KR at 2013 - KR Gathering in Mt. Vernon, Il - MVN 

Best Interior at 2013 - KR Gathering in Mt. Vernon, Il - MVN 

Best Paint at 2013 - KR Gathering in Mt. Vernon, Il - MVN 

Best Firwwall Forward at 2013 - KR Gathering in Mt. Vernon, Il - MVN 



Best Interior and Panel at 2008 - KR Gathering in Mt. Vernon, Il - MVN





Daniel R. Heath - Lexington, SC





-Original Message-...Can anyone of the experienced
"bellybrakers"explane ,what kind of bellybrake are the most efficent? brake
is.

.Is it useful to make holes in the brakeshield or not ?

what is the most efficent deploying angle of the board ?

___
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To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org
please see other KRnet info at http://www.krnet.org/info.html
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options

KR> Bellybrake

[Herbert Fürle]

...Can anyone of the experienced  "bellybrakers"explane ,what kind of 
bellybrake are the most efficent  brake is.
.Is it useful to make holes in the brakeshield or not ?
what is the most efficent deploying angle of the board ?

My bellyboard is mounted just under the rearspar  and actuated by a 
electro-spindle with two alternately switches to limit the braketravel.
Any helpful discusion is welcome,
Sincerely, Herbert

Von meinem iPad gesendet

KR> UK Air Traffic Visualisation

[Mike]

This is not KR related and it's not Friday but it's offered for your
entertainment!

The UK National Air Traffic Service (NATS) has just released a video (data
visualisation) of the air traffic over the UK from one day earlier this
summer. It starts by showing what comes to us from the USA each morning!

http://nats.aero/blog/2014/11/take-guided-tour-uk-skies 

Mike Mold
Devon, UK.

___
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KR> Bellybrake

[Dan Heath]

It is a mystery.  Mine had no holes and performed very well.  No holes is
easier to implement, so, for me it seemed to be the most logical choice.  I
use an electric servo that I got from Steve Glover.  It has an automatic
stop at both ends of the throw.  I started out with a momentary switch so I
could put it down a little at a time.  However, found that full throw was
always what I needed, so changed it out for simplicity.  Switch down, board
down, switch up, board up.



Manual activation may be better, but it takes up precious room in the
cockpit, so I never considered that option.



See N64KR at   http://KRBuilder.org - Then click on
the pics 



2105 KR Gathering - McMinnville, OR.  September 3 - 6 -- See U There.



Peoples Choice at 2013 - KR Gathering in Mt. Vernon, Il - MVN 

Best KR at 2013 - KR Gathering in Mt. Vernon, Il - MVN 

Best Interior at 2013 - KR Gathering in Mt. Vernon, Il - MVN 

Best Paint at 2013 - KR Gathering in Mt. Vernon, Il - MVN 

Best Firwwall Forward at 2013 - KR Gathering in Mt. Vernon, Il - MVN 



Best Interior and Panel at 2008 - KR Gathering in Mt. Vernon, Il - MVN





Daniel R. Heath - Lexington, SC





-Original Message-...Can anyone of the experienced
"bellybrakers"explane ,what kind of bellybrake are the most efficent  brake
is.

.Is it useful to make holes in the brakeshield or not ?

what is the most efficent deploying angle of the board ?

KR> Jabiru Australia CASA

[John Martindale]

There is a political aspect to this also.



CASA has limited the Jabiru engine because it is a certified engine, that
is, it is subject to the same rules as your everyday Lycoming  or
Continental.



However, where the engine is in an aircraft registered under our
Experimental or Recreational Light Sport category there seems to be some
contention as to CASA's right to apply the restriction. If shown to be
appropriate, then CASA could have the power to apply it to any non-certified
experimental engine including the VW, Corvair etc commonly used in KRs. This
is seen by many as a regulatory imposition contrary to the very foundation
of the experimental category.



The restriction is apparently based upon some statistical failure rates, the
details of which are not being released, which is making it difficult for
our representatives to provide a balanced response. Importantly the failure
rates quoted so far do not appear to be significantly different to what you
see in other certified engines which makes you wonder why Jabiru is being
singled out. 



The limitation was released in stealth with neither the engine manufacturer
nor any of the home built aircraft organisations consulted beforehand.
However it has significant financial implications for all concerned.



I would like to think that our experimental owners will take note of the
technical issues under discussion and address them appropriately using good
airmanship but the problem at present is that CASA are refusing to elaborate
what they are or justify their position. 



Our country is becoming highly over regulated and a previous CASA director
once famously said "we would have enough work to do even if there were no
aircraft flying". .such is the mind set.sound familiar.



Cheers John



John Martindale

29 Jane Circuit

Toormina NSW 2452

Australia



ph:61 2 6658 4767

m:0403 432179

email:john_martindale at bigpond.com

web site: http://john-martindale-kr2.zxq.net

-Original Message-
From: KRnet [mailto:krnet-bounces at list.krnet.org] On Behalf Of Mike
Stirewalt via KRnet
Sent: Sunday, 30 November 2014 6:40 AM
To: krnet at list.krnet.org
Subject: KR> Jabiru



Someone commented recently on the forum that CASA (Australian FAA) has

limited Jabiru-powered aircraft to day VFR...snip




-
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Checked by AVG - www.avg.com
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KR> Jabirus

[laser147 at juno.com]

Excuse me . . . I meant to include Tony King's info along with that of
John Martindale's.  They both clarified that what I stated was an
existing restriction by CASA is at this point only a proposal. 
Apparently in Australia grown men are forced to wear helmets when riding
a bicycle so this proposal surely has an element of bureaucratic
intrusion.  On the other hand, some knowledgable-sounding people down
there seem to think that CASA's attention to the failure rates of Jabiru
engines is overdue.  

Mike
KSEE



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KR> Jabirus

[laser147 at juno.com]

I did mis-spoke with my earlier post.  As John Martindale points out, the
CASA Jabiru restrictions are just a proposal at this point and also in
contention (as John also mentions) is whether CASA even has the authority
to restrict aircraft licensed in Australia's equivalent of the
Experimental category.  

I realize the vast majority of the Jabs (and Rotax's as well) go into the
Tupperware planes and don't affect many of the KR fleet, however Colin is
flying around the world with one, and Richard Shirley has the hottest KR
ever built flying behind one, so it's a relevant subject for our group. 
It's a gorgeous engine to look at but over the years my impressions have
been they always seems to have cooling problems and idiosyncracies of one
kind or another.  Colon obviously trusts his.   

Anyway, I'll leave this subject to others after this post.  If anyone
wants to get into great depth on the Jabiru situation please go to the
link below.  A number of highly knowledgable people, many if not most
from down under, commenting on all of the issues and ramifications.  If
Juno breaks the link just take out the space and patch it back together. 

http://www.pprune.org/pacific-general-aviation-questions/551168-jabiru-en
gine-failures.html

I'm re-posting below one of the submissions on the pprune.org thread
linked above which gives some data.

Mike
KSEE

Reported data for 2014 year to date (January through October)


Hours flown
Jabiru 41,834
Rotax 71,626
All 131,227

Landings
Jabiru 92,735
Rotax 145,638
All 260,383

Engine failures (full or partial)
Jabiru 28
Rotax 16
All 51

That makes Jabiru 0.67 per thousand hours, Rotax 0.22 and others 0.39.

Jabs way in front, if the stats are complete (which they may not be,
based on track record). Even if they aren't, it's a wide margin.

Odd Trick Fights Diabetes
Unique Proven Method To Control Blood Sugar In 3 Weeks. Watch Video.
http://thirdpartyoffers.juno.com/TGL3141/547ae77212d11677129d7st01vuc