Today's Message Index:
----------------------
1. 05:33 AM - Re: Essential Bus question (R. curtis)
2. 08:09 AM - Teaching vs. Propagandizing (Robert L. Nuckolls, III)
3. 08:35 AM - Batteries and step down converters (donjohnston)
4. 09:14 AM - Re: Batteries and step down converters (Tim Andres)
5. 09:59 AM - Re: Batteries and step down converters (Eric Page)
6. 10:38 AM - Small Connector for Ray Allen Trim Servo Cables? (Valin)
7. 10:54 AM - Re: Small Connector for Ray Allen Trim Servo Cables? (Robert L. Nuckolls, III)
8. 10:58 AM - Re: Small Connector for Ray Allen Trim Servo Cables? (Eric Page)
9. 10:59 AM - Re: Batteries and step down converters (Robert L. Nuckolls, III)
10. 11:09 AM - Re: Small Connector for Ray Allen Trim Servo Cables? (rparigor@suffolk.lib.ny.us)
11. 11:12 AM - Re: Small Connector for Ray Allen Trim Servo Cables? (Robert L. Nuckolls, III)
12. 11:42 AM - Off the shelf product update (Robert L. Nuckolls, III)
13. 12:13 PM - Relay for OV Protection (Thomas E Blejwas)
14. 01:43 PM - Re: Relay for OV Protection (Robert L. Nuckolls, III)
15. 01:45 PM - Re: Teaching vs. Propagandizing (Richard Girard)
16. 02:15 PM - Re: Teaching vs. Propagandizing (Robert L. Nuckolls, III)
17. 03:02 PM - Re: Teaching vs. Propagandizing (Robert Borger)
18. 06:32 PM - Re: Analyze This (user9253)
19. 06:51 PM - Re: Relay for OV Protection (Thomas E Blejwas)
20. 09:02 PM - Re: Re: Analyze This (Jeff Luckey)
Message 1
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Subject: | Re: Essential Bus question |
You also have to take into account that unlike the LyCo's, the Rotax has a
five piece crank that is pressed together with nothing but the pressure of
the fit to keep it together and aligned. I would imagine the trail of tear
s would include a piston seizure that causes the crank to come out of align
ment which not only destroys a bearing or two, but gives the various crank
sections a chance to beat upon each other. The reason for the multipiece cr
ank is so that it can be made shorter by reducing the clearance between the
side of the rod, see picture. With so little clearance between the rod and
the adjacent crank web the twisted, misaligned crank now has a chance to r
eally start beating on the rods, the piston skirts, and any pieces that hav
e come loose. Of course the Rotax engineers have reduced clearances between
the rotating assembly and the case halves to shave off more weight and by
now the bearings are not only being twisted out of their seats but the case
webs are being hammered, too.
I find this scenerio to be highly unlikely! If this were the case, t
hen I would wager that there would be cases of this type of failure during
normal operation, due to the stress and vibration created during high power
running.
Roger
--
Do you have a slow PC=3F Try a Free scan http://www.spamfighter.com/SLOW-PCfi
ghter=3Fcid=sigen
Message 2
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Subject: | Teaching vs. Propagandizing |
At 08:23 PM 2/3/2014, you wrote:
>Bob, You also have to take into account that unlike the LyCo's, the
>Rotax has a five piece crank that is pressed together with nothing
>but the pressure of the fit to keep it together and aligned. <snip>
>Rotax engines are just a different animal.
Understand. This isn't a study in design
philosophies. It's a sifting of the simple
ideas in work -> heat -> loss of finish ->
more heat -> destruction over time.
Temperature rise in mass is a time dependent
phenomenon. The parts at risk of failure
need to take on energy that begins with a
very low value (new, slick surfaces) and builds
as the level of destruction advances.
Most engines run minutes producing a high
percentage of rated power with no more oil
on moving parts than that which was used to
assemble it. Then there's the notion that
destruction of cylinder walls (of significant
mass with water on the other side) had
anything to do with rod failure that went
from start to completion in 10 seconds.
I've spend a lot of my career sifting
through narratives for the purpose of
assembling data bits into a coherent picture
of cause and effect. "No piston
lube resulted in breaking a rod and
pushing the end through the crankcase
at 1000 rpm" does not paint a coherent
picture.
There is MUCH that is not said/known
and as such is a poor tool for educating
the listener with any better understanding
than they get from watching a Hollywood
portrayal of fantastic physics. Memorable
perhaps but it's akin to telling our
kids they'd better behave or the "boggy
man is going to get you." We've conducted
similar exercises here on the List with
close examination of narratives in the
flying rags that I've dubbed "dark-
n-stormy-night" stories. In this case:
"Better not have your EFIS system rebooting
right after start up lest the engine put
a rod through the crankcase."
The difference between teacher and propagandist
is the ability to bring all the simple-ideas
in a narrative together for that coherent
picture. The puzzle may be ten pieces or
1000 pieces but until they've been
fitted into place, the integrity of the
narrative is suspect.
Remember that math teacher who insisted
you write down all the steps for solving
a problem? The goal WAS NOT to get to the
right answer on one problem . . . the goal
WAS to understand HOW to get to the right
answer on all problems.
Bob . . .
Message 3
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Subject: | Batteries and step down converters |
Two totally unrelated questions...
1) To keep my primary EFIS up during engine start, I'm thinking of using a small
battery (I will need two since I've got a 24v system). I've seen mention of
people using 7ah batteries for this. What manufacture/model battery people are
using?
2) I've got one device that is only available in a 12v version. I was going to
get this step down converter from Lone Star.
http://www.lonestaraviation.com/Step-Down-Conveter-24V-to-13.8-Volts.html
Then I ran across this one at 1/5th the cost.
http://www.pyleaudio.com/sku/PSWNV480/24V-DC-to-12V-DC-Power-Step-Down-480-Watt--Converter-W-PMW-Technology
I'm wondering if it's likely that there is a fundamental difference between the
two beyond one of them being for the aviation market.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=418075#418075
Message 4
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Subject: | Re: Batteries and step down converters |
I think most any of them will run on 12 volts just fine. If so no need to convert
it. Here's what I use:
http://www.batteriesplus.com/product/46043-WKA12--7F-12V-7Ah-AGM-Battery/566-0/8183-Emergency-Light-Security-Battery/655122-Moose/Z1100-Security-Alarm.aspx
Tim
> On Feb 4, 2014, at 8:34 AM, "donjohnston" <don@velocity-xl.com> wrote:
>
>
> Two totally unrelated questions...
>
> 1) To keep my primary EFIS up during engine start, I'm thinking of using a small
battery (I will need two since I've got a 24v system). I've seen mention of
people using 7ah batteries for this. What manufacture/model battery people are
using?
>
> 2) I've got one device that is only available in a 12v version. I was going to
get this step down converter from Lone Star.
> http://www.lonestaraviation.com/Step-Down-Conveter-24V-to-13.8-Volts.html
>
> Then I ran across this one at 1/5th the cost.
> http://www.pyleaudio.com/sku/PSWNV480/24V-DC-to-12V-DC-Power-Step-Down-480-Watt--Converter-W-PMW-Technology
>
> I'm wondering if it's likely that there is a fundamental difference between the
two beyond one of them being for the aviation market.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=418075#418075
>
>
>
>
>
>
>
>
>
>
Message 5
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Subject: | Re: Batteries and step down converters |
What device are you planning to power from such a DC/DC converter that needs a
supply capable of 10-20 amps?
Lone Star's prices reflect the high cost of TSO compliance testing and, as you
suggested, application of the word "aviation" to their products. That said, I'll
bet they're high quality. The Pyle... who knows?
As long as in-flight failure of the connected device would have no safety implications,
I wouldn't hesitate to use the Pyle converter, or indeed any you might
find on eBay for even less $, smaller size and lower weight.
Perhaps this: http://bit.ly/1frGS3M -or this- http://bit.ly/1eQFmXj -or this- http://bit.ly/LM7x2A
Or, if 5A current capacity is enough, this: http://bit.ly/1n8N17Y
Search eBay for "DC buck" and you'll get endless hits.
I would figure out the peak current draw of your device, double it, and buy a converter
with that capability to assure adequate supply without high operating
temps. I wouldn't lose much sleep about reliability; if a converter functions
out of the box, it's probably unlikely to fail later, assuming it's not driven
to absurd temperatures or subjected to mechanical abuse.
Eric
On Feb 4, 2014, at 9:34 AM, "donjohnston" <don@velocity-xl.com> wrote:
>
> Two totally unrelated questions...
>
> 1) To keep my primary EFIS up during engine start, I'm thinking of using a small
battery (I will need two since I've got a 24v system). I've seen mention of
people using 7ah batteries for this. What manufacture/model battery people are
using?
>
> 2) I've got one device that is only available in a 12v version. I was going to
get this step down converter from Lone Star.
> http://www.lonestaraviation.com/Step-Down-Conveter-24V-to-13.8-Volts.html
>
> Then I ran across this one at 1/5th the cost.
> http://www.pyleaudio.com/sku/PSWNV480/24V-DC-to-12V-DC-Power-Step-Down-480-Watt--Converter-W-PMW-Technology
>
> I'm wondering if it's likely that there is a fundamental difference between the
two beyond one of them being for the aviation market.
Message 6
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Subject: | Small Connector for Ray Allen Trim Servo Cables? |
Hello,
Can anyone recommend a good, small, preferably environmentally sealed connector
to use on the five conductor cable of 22 AWG wires that run to each of the Ray
Allen trim servos? If I werent going to be flying in primer first Id probably
just splice the wires together for the entire run. But with paint and control
surface removal in the known future Id like to make removal of the control
surfaces easier with connectors on these cables. They need to be low volume
connectors to fit in the space where theyll be.
Thanks,
Valin Thorn
Lancair Legacy Project
Boulder, Colorado
BTW, when I try to email in questions to the list nothing comes through for me.
So posting directly to the AeroElectric List Forum.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=418080#418080
Message 7
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Subject: | Re: Small Connector for Ray Allen Trim Servo Cables? |
At 12:38 PM 2/4/2014, you wrote:
Hello,
Can anyone recommend a good, small, preferably
environmentally sealed connector to use on the
five conductor cable of 22 AWG wires that run to
each of the Ray Allen trim servos? If I
werent going to be flying in primer first
Id probably just splice the wires together for
the entire run. But with paint and control
surface removal in the known future Id like to
make removal of the control surfaces easier with
connectors on these cables. They need to be low
volume connectors to fit in the space where theyll be.
Thanks,
Valin Thorn
Lancair Legacy Project
Boulder, Colorado
BTW, when I try to email in questions to the list
nothing comes through for me. So posting
directly to the AeroElectric List Forum.
Not sure what you mean by 'email to the list'
Using aeroelectric-list@matronics.com in your address
is the only way to post to the list server and in this
case, it seems to have worked for you.
Why 'environmentally sealed' . . . that opens
a huge catalog of choices few of which offer
a good return on investment.
Consider this:
http://tinyurl.com/cmq7epd
. . . for reducing the profile on a d-sub
to allow threading through the lightening
holes on an RV . . . not sure what your
cable routing constraints are . . . perhaps
a stock pair of D-Sub9 connectors would
fit.
If you're committed to the environmentally
sealed variety heres an exemplar selection
http://tinyurl.com/n3auqc4
http://tinyurl.com/k883l97
I think you'll find the rudimentary D-Subs
adequate to the task.
Bob . . .
Message 8
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Subject: | Re: Small Connector for Ray Allen Trim Servo Cables? |
Weather Pack connectors should do the trick, assuming they fit your space co
nstraints. The 5-pin is a bit bulky, but a 2-pin and a 3-pin offset from on
e another might work. They're even available as pigtails so you don't need t
he crimp tool.
http://www.whiteproducts.com/weather_pack.shtml
Eric
On Feb 4, 2014, at 11:38 AM, "Valin" <thorn@starflight.aero> wrote:
> Hello,
>
> Can anyone recommend a good, small, preferably environmentally sealed conn
ector to use on the five conductor cable of 22 AWG wires that run to each of
the Ray Allen trim servos? If I weren=99t going to be flying in prim
er first I=99d probably just splice the wires together for the entire r
un. But with paint and control surface removal in the known future I=99
d like to make removal of the control surfaces easier with connectors on the
se cables. They need to be low volume connectors to fit in the space where t
hey=99ll be.
>
> Thanks,
>
> Valin Thorn
> Lancair Legacy Project
> Boulder, Colorado
Message 9
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Subject: | Re: Batteries and step down converters |
At 10:34 AM 2/4/2014, you wrote:
Two totally unrelated questions...
1) To keep my primary EFIS up during engine start, I'm thinking of
using a small battery (I will need two since I've got a 24v system).
I've seen mention of people using 7ah batteries for this. What
manufacture/model battery people are using?
What is the input voltage requirement for your
electro-whizzies. Many contemporary products now
use switch-mode power supplies with a wide range
of acceptable inputs . . . typically 0-32 volts.
If your devices are of this generation, then you
don't need brownout protection in a 28v system . . .
starter inrush drain won't pull your bus below
10 volts and the glass will stay powered up.
The problem arises when a device with a 10v minimum
input voltage sees a drop to 7-8 volts during starter
inrush events.
2) I've got one device that is only available in a 12v version. I was
going to get this step down converter from Lone Star.
http://www.lonestaraviation.com/Step-Down-Conveter-24V-to-13.8-Volts.html
Then I ran across this one at 1/5th the cost.
http://www.pyleaudio.com/sku/PSWNV480/24V-DC-to-12V-DC-Power-Step-Down-480-Watt--Converter-W-PMW-Technology
I'm wondering if it's likely that there is a fundamental difference
between the two beyond one of them being for the aviation market.
What is the device you're fitting with the down-converter
and what are its input demands?
Bob . . .
Message 10
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Subject: | Re: Small Connector for Ray Allen Trim Servo Cables? |
Hi Valin
We were going to use D-sub connector with no shell, use Goop to hold
wires to connector and heat shrink together (this was one of Bobs ideas,
I am pretty sure he has instructions for this).
Since we have an inspection cover close to the servo, insteads of using a
connector we just stagger soldered wires and heat shrunk, leaving a
service loop to allow us to unsolder if servo ever needed replacement or
removal.
In addition we marked on a white piece of heat shrink which wires you
would want to connect to a 9 volt battery to jog to a somewhat neutral
position to get you home in the event the pitch circuit failed.
Details:
http://www.europaowners.org/main.php?g2_itemId=30484
Ron Parigoris
Message 11
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Subject: | Re: Small Connector for Ray Allen Trim Servo Cables? |
>They need to be low volume connectors to fit in the space where theyll be.
>
>Thanks,
If you've got a really tight size restriction, then
there are some pretty compact but still well enclosed
connectors from Lemo
http://tinyurl.com/p4ycw9p
I used these on a couple of programs at Beech . . . but
they come in so many assembly options that nobody stocks
many ready-to-install combinations. Both times I needed
4 and 5 wire connectors, they were ordered in from a
Lemo distribution facility that custom assembled to the
desired option. Cost about $40 each half plus back
shells and 6 week lead time.
Nice connectors tho . . .
Bob . . .
Message 12
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Subject: | Off the shelf product update |
A few weeks ago we were discussing several design
goals that would benefit from the incorporation
of solid state relays. At that time I cruised the
offerings on eBay and purchased this item
http://tinyurl.com/l2v72uf
Emacs!
This is a DC/DC solid state relay rated for switching
up to 60 volts at 100 amps. I selected the 100 amp
rated device based on the notion that mos-fet transistors
rated for the greatest currents tend to have the lowest
On-Resistance ratings. I've used many 'oversized'
transistors in a task not because I needed some
'headroom' for reliability . . . but because I wanted
the lowest practical on-resistance which in turn
produces the simplest heat rejection problem.
When the first relay arrived, I biased the critter
up on a 20A constant current supply and it exhibited
a voltage drop on the order of 5 volts . . . obviously
unsuited to the task at any current level.
Wrote to the seller who was wanting to see
schematics on how I had wired it up . . . but who
didn't have a clue as to how it was supposed to
work. I finally lodged a complaint with eBay for
merchandise not as advertised.
The seller responded with an offer to replace it
and I received the second part directly from the
factory yesterday. This part does perform much
better . . . only 0.5 volts drop at 20A and probably
less than the advertised 1.0 volt drop at 100A.
I closed the 'gripe' with the eBay seller.
This discovery demonstrates the designers unwillingness
to 'bootstrap' the gate supplies to his power
FETs for the purpose of achieving the lowest possible
on-resistance . . . hence the lowest possible heat
dissipation.
This product is offered by many eBay sellers and
I've found a few bad-reviews . . . but for the
most part, these critters seem to operate as
advertised.
But we can do better . . .
I've got a 20A package I'm working with that is
in a plastic enclosure and requires NO heat-sink.
But it wont sell for $13 either.
I can recommend the product offered on eBay for
situations where the MINIMUM drop on the order
of 0.5 volts is not a stumbling point. At $13, its
a good value. I would not operate it at much more
than 20A for the same heat-rejection issues
we've been deliberating here on the list for
bus power steering diodes.
I'm going to throw the SSR in the goodies-bin
and move on . . . might have a place I can use
it on my truck someday.
Bob . . .
Message 13
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Subject: | Relay for OV Protection |
In modifying Z-07 or Z-19 for my Viking engine, I will add over-voltage protection
for the Viking-supplied, internally regulated, 40A alternator by ND. Based
in part on Bob's demonstration in the literature of a type 70 contactor opening
under simulated o.v. conditions, I'd started to plan on such a relay/contactor
instead of spending over $200 on an EV200 or similar. But since the relay
is not in the starting loop, could I use a stout auto relay instead? I recently
became aware of the Picker 7150 (now sold by Waytek) that has ratings of
75V switching voltage and 150A for continuous load and breaking. It has 3/8"
quick tabs for the load, but connectors for #8 wire are available from Digikey.
Advantages would be weight (2.1 oz.) and electrical draw (2.9W). Are there
potential problems? Btw, I'm not concerned with it surviving an o.v. event,
since it would cost $20 or so to replace. Thanks in advance for any feedback.
Tom
Sent from my iPad
Message 14
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Subject: | Re: Relay for OV Protection |
At 02:12 PM 2/4/2014, you wrote:
<tomblejwas@yahoo.com>
In modifying Z-07 or Z-19 for my Viking engine, I will add
over-voltage protection for the Viking-supplied, internally
regulated, 40A alternator by ND. Based in part on Bob's
demonstration in the literature of a type 70 contactor opening under
simulated o.v. conditions, I'd started to plan on such a
relay/contactor instead of spending over $200 on an EV200 or
similar. But since the relay is not in the starting loop, could I
use a stout auto relay instead? I recently became aware of the
Picker 7150 (now sold by Waytek) that has ratings of 75V switching
voltage and 150A for continuous load and breaking. It has 3/8" quick
tabs for the load, but connectors for #8 wire are available from
Digikey. Advantages would be weight (2.1 oz.) and electrical draw
(2.9W). Are there potential problems? Btw, I'm not concerned with
it surviving an o.v. event, since it would cost $20 or so to
replace. Thanks in advance for any feedback.
Tom
Give it a try! The ratings are good.
http://tinyurl.com/kwlvfj2
I note that they come with built in coil
suppression that appears to be a plain vanilla
diode.
Your "high-risk" features are centered more on
the connectors and crimps than on the relay.
Of all the S700-3 switches 'smoked' by strobe systems,
I don't think we've seen any evidence of contact's
ill suited to the task. We've seen terminals overheat
and do the precipitous slide to smoke and fire, also
compression joints across plastic housings (tabs
held by rivets) and even some 'teeter totters' that
annealed and deformed . . . but the contacts looked
fine.
What we're learning here is the value of gas-tight
integrity for made up joints . . . they appear
far more vulnerable to abusive electron flows than
the actual controlling contacts.
With 3/8" fast-on tabs, you might consider drilling
them for #6 screw and using ring terminals to attach.
I think I'd go for a soldered-on non insulated
ring terminal too. With due diligence to your made
up joints, odds for success are quite good.
Now for the caveats . . . this is a plastic enclosure
and a runaway IR alternator ALWAYS goes into self
destruct by putting something on the order of 200 volts
on its own field winding - and nearly as much on the
b-lead disconnect relay. The only concern I have is
for the possibility of internal-eternal fire getting
outside the housing . . . this was not a concern with
the metal housed Model 70.
Bob . . .
Message 15
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Subject: | Re: Teaching vs. Propagandizing |
Bob et al, It's been seven years since I saw that engine at Lockwoods. At
the time I didn't think to take pictures, however I have a request in to
Dean Vogel, there, to see if I can get one or two pictures of it.
I've had the misfortune to blow up an engine or two over the last 50 years.
The first was an Alfa Romeo four cylinder that blew a head gasket. I had
just had the engine rebuilt after I over revved it and spun a rod bearing.
The book said to re-torque the head every 1300 miles. I had a date and
thought I could get it the next morning. Sure enough, white steam began
pouring out of the exhaust a block from her house. The trip odometer said
the engine had 1317 miles on it. The fellow I sold the car to did the same
thing. Dave, as I recall, got a little over that but did not reach 1400
miles. Alfa was quite serious about the 1300 mile re-torquing. I was 19 and
it made an impression on me that the manufacturer generally knows his
product.
Back to the Rotax. First, your assumption that it would idle at 1000 rpm.
It's a geared engine that idles at 1800 to 2200. Kinetic energy increases
at the square of the speed, does it not? So we have around 4 times the
energy from the idle speed you used as an example.
Rotax piston fits. As I said, somewhere back, the allowable piston to
cylinder fit for a 912 is .0000 to .0009". It is perfectly acceptable to
have a size on size fit up. Even at .0009" it does not take much to seize a
piston.
When I examined the damage, one of the things that impressed me was the
absence of metal discoloration or burned oil on the parts, in this case
break in lube. This is why my recreation of events concentrated on the
failure of the built up crank. I just didn't see the damage signature that
I've seen in a typical rod failure event. What there was, was a lot of
impact damage.
If I'm lucky enough to get a picture or two, I'll pass them along.
Rick
On Tue, Feb 4, 2014 at 10:08 AM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> nuckolls.bob@aeroelectric.com>
>
> At 08:23 PM 2/3/2014, you wrote:
>
>> Bob, You also have to take into account that unlike the LyCo's, the Rotax
>> has a five piece crank that is pressed together with nothing but the
>> pressure of the fit to keep it together and aligned. <snip> Rotax engines
>> are just a different animal.
>>
>
> Understand. This isn't a study in design
> philosophies. It's a sifting of the simple
> ideas in work -> heat -> loss of finish ->
> more heat -> destruction over time.
>
> Temperature rise in mass is a time dependent
> phenomenon. The parts at risk of failure
> need to take on energy that begins with a
> very low value (new, slick surfaces) and builds
> as the level of destruction advances.
>
> Most engines run minutes producing a high
> percentage of rated power with no more oil
> on moving parts than that which was used to
> assemble it. Then there's the notion that
> destruction of cylinder walls (of significant
> mass with water on the other side) had
> anything to do with rod failure that went
> from start to completion in 10 seconds.
>
> I've spend a lot of my career sifting
> through narratives for the purpose of
> assembling data bits into a coherent picture
> of cause and effect. "No piston
> lube resulted in breaking a rod and
> pushing the end through the crankcase
> at 1000 rpm" does not paint a coherent
> picture.
>
> There is MUCH that is not said/known
> and as such is a poor tool for educating
> the listener with any better understanding
> than they get from watching a Hollywood
> portrayal of fantastic physics. Memorable
> perhaps but it's akin to telling our
> kids they'd better behave or the "boggy
> man is going to get you." We've conducted
> similar exercises here on the List with
> close examination of narratives in the
> flying rags that I've dubbed "dark-
> n-stormy-night" stories. In this case:
> "Better not have your EFIS system rebooting
> right after start up lest the engine put
> a rod through the crankcase."
>
> The difference between teacher and propagandist
> is the ability to bring all the simple-ideas
> in a narrative together for that coherent
> picture. The puzzle may be ten pieces or
> 1000 pieces but until they've been
> fitted into place, the integrity of the
> narrative is suspect.
>
> Remember that math teacher who insisted
> you write down all the steps for solving
> a problem? The goal WAS NOT to get to the
> right answer on one problem . . . the goal
> WAS to understand HOW to get to the right
> answer on all problems.
>
>
> Bob . . .
>
>
--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
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Subject: | Re: Teaching vs. Propagandizing |
At 03:40 PM 2/4/2014, you wrote:
>Bob et al, It's been seven years since I saw that engine at
>Lockwoods. At the time I didn't think to take pictures, however I
>have a request in to Dean Vogel, there, to see if I can get one or
>two pictures of it.
<snip>
>If I'm lucky enough to get a picture or two, I'll pass them along.
Great. If he could also expand the narrative to
explain the sequence of events along with photos
of the participating features . . .
Bob . . .
Message 17
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Subject: | Re: Teaching vs. Propagandizing |
Gents,
This thread should probably be on the Rotax list, but sometimes we take what we
can get where we can get it.
I too have attended Lockwoods 91X class and have seen the engine and heard the
story from Dean. There was also a second story related which involved loss of
oil due to vibrational damage to an extended fitting to mount the oil pressure
sensor. A fitting was inserted between the oil pressure sender and the engine
case. The fitting was put in place to add a pressure switch to illuminate
a light should the oil pressure drop below the switch pressure set point. Now
you have a classic mass on a spring with the sender hanging out on that extension.
I dont remember how long that arrangement held up but I dont believe it
was very long before the extension piece broke, the gentlemans low oil pressure
lamp illuminated and the contents of the oil sump were dumped overboard. Again,
the report was that the engine probably didnt run longer than 10-20 second
before it seized once the oil was gone. I cant speak to the accuracy of the
10-20 seconds without oil before seizure not having been there in either case.
But the takeaway point was that the Rotax 91X engine requires continuous lubrication
and that any interruption in that lubrication would be detrimental
to your engine.
BTW, I have moved my oil pressure sender off the engine and onto the firewall using
a length of SS braided pressure line. Saves vibrational stresses on the
sender and the fitting to the engine.
One of the many things I like about my Grand Rapids EIS 4000 is that it stays up
during engine start and the default page shows oil pressure so I know immediately
upon engine start if theres oil pressure.
Just my 2 and worth at least half that.
Blue skies & tailwinds,
Bob Borger
Europa XS Tri, Rotax 914, Airmaster C/S Prop (50 hrs).
Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
3705 Lynchburg Dr.
Corinth, TX 76208-5331
Cel: 817-992-1117
rlborger@mac.com
On Feb 4, 2014, at 3:40 PM, Richard Girard <aslsa.rng@gmail.com> wrote:
Bob et al, It's been seven years since I saw that engine at Lockwoods. At the time
I didn't think to take pictures, however I have a request in to Dean Vogel,
there, to see if I can get one or two pictures of it.
I've had the misfortune to blow up an engine or two over the last 50 years. The
first was an Alfa Romeo four cylinder that blew a head gasket. I had just had
the engine rebuilt after I over revved it and spun a rod bearing. The book said
to re-torque the head every 1300 miles. I had a date and thought I could get
it the next morning. Sure enough, white steam began pouring out of the exhaust
a block from her house. The trip odometer said the engine had 1317 miles on
it. The fellow I sold the car to did the same thing. Dave, as I recall, got a
little over that but did not reach 1400 miles. Alfa was quite serious about the
1300 mile re-torquing. I was 19 and it made an impression on me that the manufacturer
generally knows his product.
Back to the Rotax. First, your assumption that it would idle at 1000 rpm. It's
a geared engine that idles at 1800 to 2200. Kinetic energy increases at the square
of the speed, does it not? So we have around 4 times the energy from the
idle speed you used as an example.
Rotax piston fits. As I said, somewhere back, the allowable piston to cylinder
fit for a 912 is .0000 to .0009". It is perfectly acceptable to have a size on
size fit up. Even at .0009" it does not take much to seize a piston.
When I examined the damage, one of the things that impressed me was the absence
of metal discoloration or burned oil on the parts, in this case break in lube.
This is why my recreation of events concentrated on the failure of the built
up crank. I just didn't see the damage signature that I've seen in a typical
rod failure event. What there was, was a lot of impact damage.
If I'm lucky enough to get a picture or two, I'll pass them along.
Rick
Message 18
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Subject: | Re: Analyze This |
Most aircraft are wired so that starter motor current comes from the battery, through
the master contactor, then through the starter contactor to the starter
motor. Then if the starter contactor sticks closed, the pilot can break the
circuit by shutting off the master switch. I modified Jeff's circuit (attached).
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=418101#418101
Attachments:
http://forums.matronics.com//files/starter_circuit_194.pdf
Message 19
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Subject: | Re: Relay for OV Protection |
Thanks Bob. I particularly appreciate the caveat. If the runaway can really get
to 200V in 5 ms, then I will have a hard time evaluating the potential risk.
Tom
Sent from my iPad
> On Feb 4, 2014, at 2:42 PM, "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
wrote:
>
>
> At 02:12 PM 2/4/2014, you wrote:
>
> In modifying Z-07 or Z-19 for my Viking engine, I will add over-voltage protection
for the Viking-supplied, internally regulated, 40A alternator by ND. Based
in part on Bob's demonstration in the literature of a type 70 contactor opening
under simulated o.v. conditions, I'd started to plan on such a relay/contactor
instead of spending over $200 on an EV200 or similar. But since the relay
is not in the starting loop, could I use a stout auto relay instead? I recently
became aware of the Picker 7150 (now sold by Waytek) that has ratings
of 75V switching voltage and 150A for continuous load and breaking. It has 3/8"
quick tabs for the load, but connectors for #8 wire are available from Digikey.
Advantages would be weight (2.1 oz.) and electrical draw (2.9W). Are there
potential problems? Btw, I'm not concerned with it surviving an o.v. event,
since it would cost $20 or so to replace. Thanks in advance for any feedback.
>
> Tom
>
> Give it a try! The ratings are good.
>
> http://tinyurl.com/kwlvfj2
>
> I note that they come with built in coil
> suppression that appears to be a plain vanilla
> diode.
>
> Your "high-risk" features are centered more on
> the connectors and crimps than on the relay.
>
> Of all the S700-3 switches 'smoked' by strobe systems,
> I don't think we've seen any evidence of contact's
> ill suited to the task. We've seen terminals overheat
> and do the precipitous slide to smoke and fire, also
> compression joints across plastic housings (tabs
> held by rivets) and even some 'teeter totters' that
> annealed and deformed . . . but the contacts looked
> fine.
>
> What we're learning here is the value of gas-tight
> integrity for made up joints . . . they appear
> far more vulnerable to abusive electron flows than
> the actual controlling contacts.
>
> With 3/8" fast-on tabs, you might consider drilling
> them for #6 screw and using ring terminals to attach.
> I think I'd go for a soldered-on non insulated
> ring terminal too. With due diligence to your made
> up joints, odds for success are quite good.
>
> Now for the caveats . . . this is a plastic enclosure
> and a runaway IR alternator ALWAYS goes into self
> destruct by putting something on the order of 200 volts
> on its own field winding - and nearly as much on the
> b-lead disconnect relay. The only concern I have is
> for the possibility of internal-eternal fire getting
> outside the housing . . . this was not a concern with
> the metal housed Model 70.
>
>
>
> Bob . . .
>
>
>
>
Message 20
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Subject: | Re: Analyze This |
I chose the "non-traditional" approach because:=0A1. Contactor sticking is
exceedingly rare=0A2. I did not want cranking to be dependent on 2 contacto
rs=0A3. It allows for more choices when selection a master relay=0A=0A=0A
=0A=0A________________________________=0A From: user9253 <fransew@gmail.com
>=0ATo: aeroelectric-list@matronics.com =0ASent: Tuesday, February 4, 2014
6:31 PM=0ASubject: AeroElectric-List: Re: Analyze This=0A =0A=0A--> AeroEle
ctric-List message posted by: "user9253" <fransew@gmail.com>=0A=0AMost airc
raft are wired so that starter motor current comes from the battery, throug
h the master contactor, then through the starter contactor to the starter m
otor.- Then if the starter contactor sticks closed, the pilot can break t
he circuit by shutting off the master switch.- I modified Jeff's circuit
(attached).=0AJoe=0A=0A--------=0AJoe Gores=0A=0A=0A=0A=0ARead this topic o
nline here:=0A=0Ahttp://forums.matronics.com/viewtopic.php?p=418101#41810
1=0A=0A=0A=0A=0AAttachments: =0A=0Ahttp://forums.matronics.com//files/start
- - - - - - - - - - - - -Matt Dralle, List Admin.
====
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