Today's Message Index:
----------------------
1. 04:23 AM - Re: Replacement batteries` (A. Dennis Savarese)
2. 05:21 AM - Re: Replacement batteries` (Mark Davis)
3. 06:33 AM - Replacement Battery (A. Dennis Savarese)
4. 07:12 AM - Re: Replacement batteries` (PeteAbbott@aol.com)
5. 07:16 AM - Re: Hard starting CJ (CJcanuck)
6. 07:30 AM - Tragic loss (Richard Goode)
7. 09:38 AM - Re: Replacement batteries` (doug sapp)
8. 11:17 AM - Engines, props (Jerry Painter)
9. 11:59 AM - Re: Tragic loss (A. Dennis Savarese)
10. 12:24 PM - Re: Replacement batteries` (Jon Boede)
11. 01:01 PM - Re: Replacement batteries` (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
12. 01:31 PM - Re: Engines, props (cjpilot710@aol.com)
13. 02:27 PM - Re: Fw: L/D redux (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
Message 1
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| Subject: | Re: Replacement batteries` |
These batteries can usually be purchased locally at a Batteries Plus or
Battery Source store or other local battery suppliers in your area. We
recently purchased 6 of the same type at a local Battery Source store.
I found your battery on-line at:
http://www.batteryuniverse.com/Sealed-Lead-Acid/B-B/EVP20-12/NPX-80_B-B_E
VP20-12_Sealed-Lead-Acid
Here is a direct replacement.
http://www.elkproducts.com/products/elk-12180.htm
Batteries Plus has similar replacement units on the shelf
http://www.batteriesplus.com/p-28223-genesis-np-12v-18ah-agm-battery-with
-nut-bolt-terminal.aspx. I found 3 different ones on their web site.
So I'm sure the stores carry at least one or two of them.
Dennis
----- Original Message -----
From: Mark Davis
To: yak-list@matronics.com
Sent: Monday, May 05, 2008 11:11 PM
Subject: Yak-List: Replacement batteries`
It's time for new batteries in my YAK. It has the BB EVP20-12
batteries from when I bought it. I have no idea where a BB Battery
dealer is in my area. Does anyone have a replacement number for an
Interstate, Optima or Yuasa battery or other recommendations?
Thanks,
Mark Davis
N44YK
Message 2
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| Subject: | Re: Replacement batteries` |
Thanks Dennis. My wife will be in Denver mid week and can pick up one
of your suggested batteries.
Mark Davis
N44YK
----- Original Message -----
From: A. Dennis Savarese
To: yak-list@matronics.com
Sent: Tuesday, May 06, 2008 5:19 AM
Subject: Re: Yak-List: Replacement batteries`
These batteries can usually be purchased locally at a Batteries Plus
or Battery Source store or other local battery suppliers in your area.
We recently purchased 6 of the same type at a local Battery Source
store. I found your battery on-line at:
http://www.batteryuniverse.com/Sealed-Lead-Acid/B-B/EVP20-12/NPX-80_B-B_E
VP20-12_Sealed-Lead-Acid
Here is a direct replacement.
http://www.elkproducts.com/products/elk-12180.htm
Batteries Plus has similar replacement units on the shelf
http://www.batteriesplus.com/p-28223-genesis-np-12v-18ah-agm-battery-with
-nut-bolt-terminal.aspx. I found 3 different ones on their web site.
So I'm sure the stores carry at least one or two of them.
Dennis
----- Original Message -----
From: Mark Davis
To: yak-list@matronics.com
Sent: Monday, May 05, 2008 11:11 PM
Subject: Yak-List: Replacement batteries`
It's time for new batteries in my YAK. It has the BB EVP20-12
batteries from when I bought it. I have no idea where a BB Battery
dealer is in my area. Does anyone have a replacement number for an
Interstate, Optima or Yuasa battery or other recommendations?
Thanks,
Mark Davis
N44YK
href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics
.com/Navigator?Yak-List
href="http://forums.matronics.com">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/c
Message 3
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| Subject: | Replacement Battery |
Mark,
Here's another source and quite a bit less expensive. Can be ordered and
shipped on-line.
http://www.safemart.com/index.asp?PageAction=VIEWPROD&ProdID=5310
Dennis
A. Dennis Savarese
334-285-2141
334-546-8182 (cell)
Skype: yakworld1
www.yak-52.com
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| Subject: | Re: Replacement batteries` |
I went to Battery Plus (box store for batteries)
They had a replacement in stock. UPS uses the same battery for their
computer system in their truck, at least that is what the guy told me.
Another guy told me the same battery is in the Jump start system that has
the short cables and you carry it to whatever.
At Sam's the complete jump system was cheaper that the battery was at
Battery Plus.
Pete
N852GC
**************Wondering what's for Dinner Tonight? Get new twists on family
favorites at AOL Food.
(http://food.aol.com/dinner-tonight?NCID=aolfod00030000000001)
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| Subject: | Re: Hard starting CJ |
No real solution found. We pulled apart the water separator (it was a mess and
ultimate replaced it), blew out what lines we could access in the engine compartment
and ran a bunch of WD-40 through the electropneumatic starter. I fired
her up a few days ago and had the usual struggle getting her going, but then
she has sat for a couple of months so I wasn't surprised. The air consumption
was more in line with what we were expecting. So.. no real answer yet.
Mike
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=181477#181477
Message 6
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I am sorry to have to report the death of Patrick Debonne, one of the top
air show pilots in France, flying a Yak-54. It would seem that he had
engine failure and a forced landing and then a fire but I have no more
information at the moment.
Richard
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340120
Fax: +44 (0) 1544 340129
www.russianaeros.com
Message 7
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| Subject: | Re: Replacement batteries` |
You might check out the dry cell Odyssey batteries, many benifits.
On Tue, May 6, 2008 at 5:17 AM, Mark Davis <mark@pld.com> wrote:
> Thanks Dennis. My wife will be in Denver mid week and can pick up one of
> your suggested batteries.
>
> Mark Davis
> N44YK
>
> ----- Original Message -----
> *From:* A. Dennis Savarese <dsavarese@elmore.rr.com>
> *To:* yak-list@matronics.com
> *Sent:* Tuesday, May 06, 2008 5:19 AM
> *Subject:* Re: Yak-List: Replacement batteries`
>
> These batteries can usually be purchased locally at a Batteries Plus or
> Battery Source store or other local battery suppliers in your area. We
> recently purchased 6 of the same type at a local Battery Source store. I
> found your battery on-line at:
> http://www.batteryuniverse.com/Sealed-Lead-Acid/B-B/EVP20-12/NPX-80_B-B_EVP20-12_Sealed-Lead-Acid
>
> Here is a direct replacement.
> http://www.elkproducts.com/products/elk-12180.htm
>
> Batteries Plus has similar replacement units on the shelf
> http://www.batteriesplus.com/p-28223-genesis-np-12v-18ah-agm-battery-with-nut-bolt-terminal.aspx.
> I found 3 different ones on their web site. So I'm sure the stores carry at
> least one or two of them.
>
> Dennis
>
>
> ----- Original Message -----
> *From:* Mark Davis <mark@pld.com>
> *To:* yak-list@matronics.com
> *Sent:* Monday, May 05, 2008 11:11 PM
> *Subject:* Yak-List: Replacement batteries`
>
> It's time for new batteries in my YAK. It has the BB EVP20-12 batteries
> from when I bought it. I have no idea where a BB Battery dealer is in my
> area. Does anyone have a replacement number for an Interstate, Optima or
> Yuasa battery or other recommendations?
>
> Thanks,
> Mark Davis
> N44YK
>
> *
>
> href="http://www.matronics.com/Navigator?Yak-List">http://www.matronhref="http://forums.matronics.com">http://forums.matronics.com
> href="http://www.matronics.com/contribution">http://www.matronics.com/c
> *
>
> *
>
> href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.com/Navigator?Yak-List
> href="http://forums.matronics.com">http://forums.matronics.com
> href="http://www.matronics.com/contribution">http://www.matronics.com/c*
>
> *
>
> *
>
>
--
Always Yakin,
Doug Sapp
Phone 509-826-4610
Fax 509-826-3644
Message 8
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Walt et al--
What unusual, if any, failure/wear modes you see in round/geared engines?
The usual valve/ring/cylinder stuff or do you see gearbox or bearing
problems?
Jim--what kind of failures in the 1830/20's etc. do you guys see on the
bombers? Or are you just being prudent? Were short engine lives in the
USAAF bearing lubrication related as described? You can imagine what combat
engines being operated off dirt, maintained in the mud, parts shortages etc
would do.
The reliability of auto racing engines is pretty amazing. I think Ferrari
F1 cars went several years between engine failures recently.
I've read some military engines had very short lives, like 4 or 5 hours,
Napier Sabre etc--way complex, lots of failure opportunities. First
airplane I owned was a '46 Bellanca with a Franklin 150. Interesting to
read factory bulletins upping the TBO every few years, beginning, I think,
with 400 hr TBO, increases usually attributed to incremental oil
improvements. We know Doug's HS6 failure was the gearbox, maybe a prop
strike lurking? Anybody had any similar problems? Been quite a few prop
strikes. I've been involved with these things for a while now myself and
with others, some with extreme abuse like you describe, Mark, and have yet
to see any reliable reports here or elsewhere about real world engine life
or weaknesses other than the usual and usually piddly stuff (that's a
scientific term sometimes used in nanobiologyurology as well as aeronautics)
and usually maintenance related, not wear or design weakness. And as for
piston speed/forces, think about all that mass flailing (another scientific
term) around in a 4360 compared to an M14, which has pistons about the same
size as in your 150's O-200, 2700 RPM redline, thank you very much. I think
4360's turn some pretty good RPM, too. Listen to them, 3350's, Merlins etc.
go by at Reno, all tightly wound, mucho boosto. Love it. Bearings, rings,
pistons sometimes fail, no surprise there.
Supercharger compression/combustion "cushion" also probably helps keep the
piston pin/rod bearing forces kinda sorta (more science) in the same
direction, too, so reverse loading could affect that, yes? I know of a few
HS6/M14 failures resulting from hydro lock damage, and have flown a few
myself with obviously bent rods and pretty severe vibration etc., but really
have never heard about any unusual problems/failures or even reliable
wear/TBO data. Most of what is described on this list is just usual
maintenance or lack thereof, not failure or even clapped out. Inquiring
people ask me about M14/HS6 real-world TBO and I have no idea.
I know guys who have run 470's etc. To more than triple TBO, got nervous so
tore them down and found everything within tolerance. I've read of a 135
freight operation, supervised carefully by the feds, going nearly 9000 hours
in tests, got nervous, tear down, all within tolerance, now run 4500 hours
or something routinely. The key to all this, of course, being continuous
use, careful monitoring, maintenance etc. Not ol' Joe who flies once in a
blue moon, 40 year TBO kinda stuff.
Doug--
Did the gearbox pack up or did the prop freewheel?
Elmar--
There are several gas and spring operated full feathering props, Hartzell
comes to mind, no accumulator required (gas/spring in the hub), don't know
if any would be suitable for M14/HS6's. Whirlwinds use a McCauley hub
designed to go to high pitch with loss of oil pressure, but not feathering,
one reason I like them, they make beautiful V530 blades, too. Don't know
about the usual others, but many/most props go flat with lost oil pressure.
Jerry Painter
Message 9
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Tragic lossMy deepest sympathy to the family and friends of Patrick.
Dennis
----- Original Message -----
From: Richard Goode
To: yak-list@matronics.com
Sent: Tuesday, May 06, 2008 9:28 AM
Subject: Yak-List: Tragic loss
I am sorry to have to report the death of Patrick Debonne, one of the
top air show pilots in France, flying a Yak-54. It would seem that he
had engine failure and a forced landing and then a fire but I have no
more information at the moment.
Richard
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340120
Fax: +44 (0) 1544 340129
www.russianaeros.com
Message 10
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| Subject: | Replacement batteries` |
We use the Odessey batteries in everything.
batterymart.com has good prices and reasonable shipping.
The batteries can be shipped as-is UPS.
And they last WAY longer, perform in MUCH harsher conditions, and last long
er without a charge than "wet" batteries.
Jon
From: dougsappllc@gmail.com
Subject: Re: Yak-List: Replacement batteries`
You might check out the dry cell Odyssey batteries, many benifits.
On Tue, May 6, 2008 at 5:17 AM, Mark Davis <mark@pld.com> wrote:
Thanks Dennis. My wife will be in Denver mid week and can pick up one of y
our suggested batteries.
Mark Davis
N44YK
----- Original Message -----
From: A. Dennis Savarese
Sent: Tuesday, May 06, 2008 5:19 AM
Subject: Re: Yak-List: Replacement batteries`
These batteries can usually be purchased locally at a Batteries Plus or Bat
tery Source store or other local battery suppliers in your area. We recent
ly purchased 6 of the same type at a local Battery Source store. I found y
our battery on-line at: http://www.batteryuniverse.com/Sealed-Lead-Acid/B-B
/EVP20-12/NPX-80_B-B_EVP20-12_Sealed-Lead-Acid
Here is a direct replacement. http://www.elkproducts.com/products/elk-12180
.htm
Batteries Plus has similar replacement units on the shelf http://www.batter
iesplus.com/p-28223-genesis-np-12v-18ah-agm-battery-with-nut-bolt-terminal.
aspx. I found 3 different ones on their web site. So I'm sure the stores
carry at least one or two of them.
Dennis
----- Original Message -----
From: Mark Davis
Sent: Monday, May 05, 2008 11:11 PM
Subject: Yak-List: Replacement batteries`
It's time for new batteries in my YAK. It has the BB EVP20-12 batteries fr
om when I bought it. I have no idea where a BB Battery dealer is in my are
a. Does anyone have a replacement number for an Interstate, Optima or Yuas
a battery or other recommendations?
Thanks,
Mark Davis
N44YK
href="http://www.matronics.com/Navigator?Yak-List">http://www.matronhref
="http://forums.matronics.com">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/c
href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.c
om/Navigator?Yak-List
href="http://forums.matronics.com">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/c
--
Always Yakin,
Doug Sapp
Phone 509-826-4610
Fax 509-826-3644
Message 11
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| Subject: | Replacement batteries` |
Not to take anything away from any particular suggestion... But if you
are going to do what most people do, and that is use two 12 volt
batteries in series, it is worth your time to just get on the Internet
and start doing some research yourself. Take the batteries you have
now, cross the part number on them, and come up with the exact 3
dimensional measurements for them, since you probably already have some
kind of "box" built to take what you already have and mount where the
old Russian battery went.
Then educate yourself on the types of batteries and their designators.
I am not talking about gell cell versus a wet electrolytic, ... I only
recommend using gell cells period. That said, there are many many types
that if you learn their designations will tell you what kind of
environment they are designed to be used in. Deep cycle, emergency
lighting, etc.
After that, try to look for a battery that is the same size as yours,
but with a larger amp/hour rating.
You will be amazed at the differences you can come up with and how you
can increase your amp/hour rating for the same size battery if you
simply look. If you can couple amp/hour with deep discharge capability,
you will have a much stronger battery.
Jon recommends Odyssey batteries and they are indeed a good product. On
the flip side, I have been using regular old Panasonic batteries and
they usually go about 4 years before needing replacement, which is
pretty darn good.
Lastly, look around and buy a battery desulfator. You can get them
extremely cheap.... Sometimes for as little as $25. These little jewels
shoot about a 3.5 Mhz RF blast into the battery in a square wave pattern
and literally blast the sulfate off the plates of the batteries,
sometimes tripling their average life time. It is an AMAZING advance in
extending battery life and worth your time to educate yourself on. I.E.
It can save you a LOT of money.
Mark Bitterlich
P.s. If you are an aerobatic pilot using the B&C batteries that go
along with their 10 amp PMG alternator.... This post most especially
applies to you.
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of Jon Boede
Sent: Tuesday, May 06, 2008 15:20
Subject: RE: Yak-List: Replacement batteries`
We use the Odessey batteries in everything.
batterymart.com has good prices and reasonable shipping.
The batteries can be shipped as-is UPS.
And they last WAY longer, perform in MUCH harsher conditions, and last
longer without a charge than "wet" batteries.
Jon
________________________________
Date: Tue, 6 May 2008 09:35:14 -0700
From: dougsappllc@gmail.com
To: yak-list@matronics.com
Subject: Re: Yak-List: Replacement batteries`
You might check out the dry cell Odyssey batteries, many
benifits.
On Tue, May 6, 2008 at 5:17 AM, Mark Davis <mark@pld.com> wrote:
Thanks Dennis. My wife will be in Denver mid week and
can pick up one of your suggested batteries.
Mark Davis
N44YK
----- Original Message -----
From: A. Dennis Savarese
<mailto:dsavarese@elmore.rr.com>
To: yak-list@matronics.com
Sent: Tuesday, May 06, 2008 5:19 AM
Subject: Re: Yak-List: Replacement batteries`
These batteries can usually be purchased locally
at a Batteries Plus or Battery Source store or other local battery
suppliers in your area. We recently purchased 6 of the same type at a
local Battery Source store. I found your battery on-line at:
http://www.batteryuniverse.com/Sealed-Lead-Acid/B-B/EVP20-12/NPX-80_B-B_
EVP20-12_Sealed-Lead-Acid
Here is a direct replacement.
http://www.elkproducts.com/products/elk-12180.htm
Batteries Plus has similar replacement units on
the shelf
http://www.batteriesplus.com/p-28223-genesis-np-12v-18ah-agm-battery-wit
h-nut-bolt-terminal.aspx. I found 3 different ones on their web site.
So I'm sure the stores carry at least one or two of them.
Dennis
----- Original Message -----
From: Mark Davis <mailto:mark@pld.com>
To: yak-list@matronics.com
Sent: Monday, May 05, 2008 11:11 PM
Subject: Yak-List: Replacement
batteries`
It's time for new batteries in my YAK.
It has the BB EVP20-12 batteries from when I bought it. I have no idea
where a BB Battery dealer is in my area. Does anyone have a replacement
number for an Interstate, Optima or Yuasa battery or other
recommendations?
Thanks,
Mark Davis
N44YK
href="http://www.matronics.com/Navigator?Yak-List">http://www.matronhref
="http://forums.matronics.com <http://forums.matronics.com/>
">http://forums.matronics.com <http://forums.matronics.com/>
href="http://www.matronics.com/contribution">http://www.matronics.com/c
href="http://www.matronics.com/Navigator?Yak-List">http://www.matronhref
=" <http://www.matronics.com/Navigator?Yak-List>
http://forums.matronics.com <http://forums.matronics.com/>
">http://forums.matronics.com <http://forums.matronics.com/>
href="http://www.matronics.com/contribution">http://www.matronics.com/c
--
Always Yakin,
Doug Sapp
Phone 509-826-4610
Fax 509-826-3644
et="_blank">http://www.matronics.com/Navigator?Yak-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
Message 12
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| Subject: | Re: Engines, props |
In a message dated 5/6/2008 2:19:11 P.M. Eastern Daylight Time,
wild.blue@verizon.net writes:
Jim--what kind of failures in the 1830/20's etc. do you guys see on the
bombers? Or are you just being prudent? Were short engine lives in the
USAAF bearing lubrication related as described? You can imagine what combat
engines being operated off dirt, maintained in the mud, parts shortages etc
would do.
The main failures we see in the 1830/20 are thrust bearings and main
bearings. Almost without fail, it usually goes "TU" soon after first power
reduction. First we get a chip light, than an oil filter bypass light. Right
after
that we get an oil pressure drop than a oil temp rise. That is an "automatic
feather" for us. Just a chip light or just a bypass light only makes us
watch that engine until the flight done. We than go to the chip detector or oil
filter, open them up for a look see.
"Dead cylinders" are the next most common problem. During the war, squadron
level maintenance never change cylinders. They would just yank the whole
engine and replace with a "QEC" which usually took just 4 hours to do. The
engine was than sent back to a depot. The most they would do is change out a
mag, starter, any of the pumps or generator. Many engine didn't last 100 or
200 hours. It was just the way they were operated. . Unbelievable time spent
at "max continuous power" in climbs that lasted hours. Constant power
changes trying to stay in formation. Plus all the imaginable climates they
operated in. Starting and stopping these takes its toll. I've been told and
seen
written here, M14p used on ground generators and pumps will run CONTINUOUSLY
for some 20,000 hours.
Jill Grenetzke has a very good article on M-14 failures in the last issue of
the "Red Alert". For us pilot types it even has pictures of the different
failures. BTW all RPA members automatically get the magazine which has a lot
of pictures.
The picture above is of #3 piston removed my engine with 438 hours fresh
purchased from Aerostar. I got a chip light and found lots of metal in the 10
micron filter. You can see that either a scraper or compression ring was put
in the oil groove instead of an oil ring. The ring was broken in about 4 or
5 pieces. A compression test found the cylinder. You can see where the
ends of the ring jammed over each end. Note too how the lands have broken down.
This same engine now has 1300 plus hours with #3 cylinder in the mid 70's.
This piston sits in a prominent spot on my hangar desk. NO I don't use as
an ash tray.
Jim "Pappy" Goolsby
**************Wondering what's for Dinner Tonight? Get new twists on family
favorites at AOL Food.
(http://food.aol.com/dinner-tonight?NCID=aolfod00030000000001)
Message 13
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Walt...
I would be glad to take this discussion off line if you would like, because I do
not want to bore people who are not interested.
Speaking to the "cushioning" effect....
There is a term in camshaft design called overlap. In cams designed with overlap,
both intake and exhaust valves can be open at the same time. Engines with
higher degrees of overlap normally do not perform well at lower RPM settings.
Engines designed with such cams usually have a sharply rising HP and Torque
curve that maximizes at a designed RPM setting. Past that setting, power will
actually diminish. Such engines normally have a very "lopey" idle, very much
like aircraft engines, which by and large do the same thing.
That said, during the cycle of exhaust followed by intake, there is very little
if any "cushion" at the top of the piston's stroke. If there was, exhaust gases
would actually flow back out the intake valve! So, one cycle out of the four
at least does not exhibit the effect you speak of, if I understand what you
are saying correctly? Does this make sense to you?
Further, in a car engine, every time you downshift and let off the gas, you are
getting the exact same effect as what we are discussing with aircraft engines.
I understand completely the issue of main bearing lubrication, which by the way
the M-14 differs quite a bit in design from American made radials, yet that said,
I do not think I am qualified enough to discuss those loading areas with
confidence.
So staying with the piston speed // compression // loading issues... I think I
see now what you are saying, but can you explain why a V-8 would not suffer a
quick death from such reverse loading as experienced when downshifting, or ...
Going down long mountain grades in a low gear... Etc., etc., yet an aircraft
engine doing the exact same thing is "bad for it".
Understand that I am not saying: YOU ARE WRONG. I am struggling to understand
in my mind how it can apply to a piston in one engine and not apply to a piston
in another.
Mark Bitterlich
-----Original Message-----
From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of Walter Lannon
Sent: Tuesday, May 06, 2008 0:19
Subject: Re: Yak-List: Fw: L/D redux
Mark; See comments below
> --> Point,
> MALS-14 64E" <mark.bitterlich@navy.mil>
>
> Walt would you please explain what you mean by "centrifugal piston
> loading" ?? I am not a radial engine expert, but I would think the
> term would be the same, and for the same reasons, as regular V-8
> racing engines, which I do have a lot of expereince with. In the
> world I come from, we call it "piston speed", and of course it is
> related to the stroke and the RPM of the engine. If we are on the
> same page of music here, the worry with the race engine I work with
> comes from the exact failure areas you speak of, which is why the
> emphasis on light weight pistons, and is also why you can easily build
> a 327 Chevy to turn 9000 RPM, but why there is much more load on a 454
> doing the same thing... Longer stroke (and thus higher piston speed)
> and heavier pistons in the 454. That said, whether the engine is
> loaded or unloaded in my training does not make any difference. When
> the piston reaches the end of it's travel and has to reverse direction, there
is tremendous forces applied al!
> l over the place, but piston pin, piston, and rod itself are the
> biggest areas of concern.
>
> To repeat and simplify, the "big force" involved is simply when the
> piston reaches the top and reverses direction. The more it weighs and
> the faster it is going when this happens means "more force".
To be honest I was desperately scratching for a descriptive word here for the forces
you have just described. Maybe sudden deceleration would have been better.
I learned about this teaching myself aerobatics in a PT26 with a Ranger engine
and of course a fixed pitch prop. (In the early 1950's there were no aerobatic
instructers around, in fact aerobatic seemed to be a dirty word).
To get enough speed for an immellman or hammerhead it was necessary to keep reducing
power in the dive in order to stay just under red line RPM. ( this was not
the worlds best aerobatic mount).
Started pulling cylinders due to low compression and found all six pistons cracked
from the pin bore. Turned out to be an early model engine that did not incorporate
piston pin plugs. The pins were being deformed by the force reversal
causing the pistons to fail.
> What I fail to understand is why this force would be larger or smaller
> when the engine is producing power, or not producing power?
I think the reason is manifold pressure or maybe more accurately brake mean effective
pressure (BMEP). The piston is "cushioned" on the compression/power cycle
by combustion forces and on the exhaust/intake cycle by exhaust expulsion and,
just before the piston reaches TDC, the input of pressurized air/fuel mixture
from the manifold.
With the larger radial engines an excess of manifold pressure (over square) is
necessary to provide this cushion. As an example the P&W R1340 numbers are - T.O.
(600 HP) 2250RPM & 36"MP, 5 min limit - Rated Power (550HP) 2200 RPM & 32.5"
MP, no limit - Typical cruise setting - (55%- 300HP) 1800 RPM & 26"MP.
Jim Goolsby sent a very informative post on this subject with an insert from Mr.
R Sohn describing the effect of these forces on the master rod bearing if the
"cushion" is not maintained.
I believe he is absolutely correct.
> Could you please explain what you mean by: "if you run significantly
> reduced power at the max. RPM for any length of time there is the
> possibility of damage due to the increased centrifugal loading of the
> piston and pin."
>
> What increased loading are you talking about assuming the engine is
> still running under maximum RPM limits? Why is there more loading
> with power off, than power on?
Covered above, I think.
The M14P is impressive. Even with the very small piston the load reversal at 2900
RPM must be awesome. That it would stand up to handling the throttle like an
ON- Off switch is mind boggling.
Aside for Pappy from a P&W devotee;
The reason the R1830 has a smaller master rod bearing is because it has TWO of
them and much smaller pistons flailing around.
Cheers,
Walt
> Mark Bitterlich
>
>
> -----Original Message-----
> From: owner-yak-list-server@matronics.com
> [mailto:owner-yak-list-server@matronics.com] On Behalf Of Walter
> Lannon
> Sent: Saturday, May 03, 2008 22:55
> To: yak-list@matronics.com
> Subject: Re: Yak-List: Fw: L/D redux
>
>
> You all are getting me confused! High RPM, low MP, overspeed??,
> contact points for the master rod bearing??, direct drive, geared
> drive. Where to
> begin---------
>
> At some point on approach you will reduce the power and, if you follow
> standard practice, will move the prop control to High RPM. If you have
> reduced power enough you will not see any RPM increase because the
> governor has sensed an underspeed condition and has already moved the
> blades to full fine.
> The only reason for moving the prop control is to set up for a
> possible emergency go-around.
> Therefore the prop is always in the highest drag condition on a normal
> landing.
>
> There can be no "overspeed" since with increasing power the governor
> will limit RPM to the max. setting. However, if you run significantly
> reduced power at the max. RPM for any length of time there is the
> possibility of damage due to the increased centrifugal loading of the piston
and pin.
> That is the primary reason for avoiding that scenario.
>
> There is no such thing as a "contact point" on the master rod bearing,
> unless it is totally worn out and nearing failure. That is the
> function of oil. It's main purpose is to ensure there is NO contact.
>
> The master rod bearing (and the inner bearing end of each link rod) is
> pressure lubricated from the crank journal cavity on ALL radial engines.
> Whether geared or direct drive makes zero difference in this area.
>
> It is possible that the M14 is more tolerant of centrifugal piston
> loading than P&W or Curtis Wright engines simply due to the small piston size.
>
> Cheers;
> Walt
>
>
> ----- Original Message -----
> From: "Roger Kemp M.D." <viperdoc@mindspring.com>
> To: <yak-list@matronics.com>
> Sent: Saturday, May 03, 2008 2:42 PM
> Subject: RE: Yak-List: Fw: L/D redux
>
>
>> <viperdoc@mindspring.com>
>>
>> Brian,
>> Thanks for enlightening me. I was not thinking about the direct drive
>> of the P&Ws verses the geared drive of the M-14. Don't quote me but I
>> believe the
>> M-14 master crank rod bearing has its own oil journal. I ran across
>> that as I was researching the oil supply of the prop governor for an
>> engine vibration occurring right at Vref.
>> It can be found in the diagrams of the M-14 engine manual.
>> Doc
>>
>> -----Original Message-----
>> From: owner-yak-list-server@matronics.com
>> [mailto:owner-yak-list-server@matronics.com] On Behalf Of Brian Lloyd
>> Sent: Saturday, May 03, 2008 11:32 AM
>> To: yak-list@matronics.com
>> Subject: Re: Yak-List: Fw: L/D redux
>>
>>
>>
>> On May 3, 2008, at 5:32 AM, Roger Kemp M.D. wrote:
>>
>>> <viperdoc@mindspring.com
>>
>>> >
>>>
>>> Jerry,
>>> I thought that by pushing the pitch to full forward on the prop at
>>> cruise manifold setting ( 600-750-800) and then pulling the MAP back
>>> to use the prop as a speed brake would put you at risk for over
>>> speeding the engine?
>>
>> Not if your prop governor is working properly.
>>
>>> Now you have set up a situation where the prop is driving the engine
>>> not the engine driving the prop. Correct me if I'm wrong.
>>
>> Yes, that is the case. But remember, when the RPM increases above the
>> set-point, the governor will drive the prop toward course pitch
>> (lower RPM). This reduces the angle-of-attack on the prop blades and
>> they will produce less lift (turning force). It is also why you get a
>> longer glide with the prop set to low RPM -- the prop is not taking
>> as much energy from the airframe to turn the engine.
>>
>>> The translated 1990 RU manual that I have says for approaches set
>>> the pitch at 80% and 400 mmHG on the advance (MAP lever)for the 52.
>>> I generally fly 70% and 400 mmHg or less (MAP) in the 50 as needed.
>>> I know at times being at say 70-80% and 750-800 mmHG chasing down
>>> someone (lead or an
>>> adversary) then
>>> pulling the MAP lever to idle to avoid overshoot is like having a
>>> big speed brake out there! The but is in the huge change in pitch of
>>> the engine. I always wondered if I was overstressing the reduction
>>> gears or the shaft itself. Honestly I would rather go idle boards
>>> (deploy the speed
>>> brakes)
>>> than use my engine as the speed brake.
>>
>> Well, think about it Roger. Do you think that the prop can generate
>> more torque turning the engine or the engine generate more torque
>> turning the prop? I think you will find that the torque is at its
>> peak when the engine is producing maximum power. That means that the
>> overall stresses on the gearbox will be less when the power is pulled
>> back.
>>
>>> I know a couple of old 17 drivers along with a 47 driver and T-28
>>> driver/maintenance officer at the airport. I will ask then their
>>> take today at our fly-in. If the weather permits!
>>
>> Now here is something you need to be careful about. You cannot assume
>> that the M14 or Huosai should be operated the same way that the big
>> Pratts and Wrights should be operated. As I understand it, the crank
>> on the Pratts and Wrights have just one oil journal and it feeds oil
>> to the contact point for the master rod bearing when the rod is
>> turning the crank. When the prop is turning the crank then the crank
>> is turning the master rod which changes the contact point. This can
>> lead to under-lubrication of the master rod bearing. That is why they
>> admonish you to never let the prop drive the engine in the Wrights
>> and Pratts.
>>
>> So that brings up the question of how the M14 and Huosai engines get
>> oil to the master rod bearing. If there are oil journals to ensure
>> proper lubrication of the master rod bearing when the prop is turning
>> the engine then there is no reason to worry about doing damage to the
>> engine when you pull the throttle back to idle. Given that the M14 is
>> intended for aerobatic use, I suspect it *does* have proper
>> lubrication when the prop is driving the engine, hence the lack of an
>> warnings about the prop driving the engine in the manuals.
>>
>> But this is only supposition on my part. Only someone who really
>> knows the engine can tell for sure.
>>
>>
>> --
>> Brian Lloyd 3191 Western Drive
>> brian HYPHEN 1927 AT lloyd DOT com Cameron Park, CA 95682
>> +1.916.367.2131 (voice) +1.270.912.0788 (fax)
>>
>> I fly because it releases my mind from the tyranny of petty things . . .
>> - Antoine de Saint-Exupry
>>
>> PGP key ID: 12095C52A32A1B6C
>> PGP key fingerprint: 3B1D BA11 4913 3254 B6E0 CC09 1209 5C52 A32A
>> 1B6C
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
>
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