Today's Message Index:
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0. 12:22 AM - Reminder (Matt Dralle)
1. 03:59 AM - Re: Wiring a Skytec Starter (Bill Watson)
2. 09:29 AM - Re: Wiring a Skytec Starter (Robert L. Nuckolls, III)
3. 02:56 PM - UPSAT Transponder (Charles Brame)
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Dear Listers,
Just a quick reminder that November is the annual List Fund Raiser. The Matronics
Lists are 100% member supported and all of the operational costs are provided
for my your Contributions during this time of the year.
Your personal Contribution makes a difference and keeps all of the Matronics Email
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Please make your Contribution today to keep these services up and running!
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Matt Dralle
Matronics Email List and Forum Administrator
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Subject: | Re: Wiring a Skytec Starter |
I have the Vans supplied LS starter for the IO-540 on my RV-10. After
initial experience with the LS starter and much consultation with other
RV10ers, I plan to replace it with an NL type starter.
Why? The LS gives me a 'saggy' kind of turnover. If the battery is
anything but topped off, and OAT is 60+, it is likey to stall out before
a full revolution. I can generally 'bounce' the prop and get it to
turnover the 2nd time. It will turn it for a long time (don't ask) but
that's a function of battery capacity.
I thought it was the Odyssey 680 battery - perhaps uncared for, worn
out, or recharged badly. I learned a lot about battery care and
maintenance but after much testing I discovered that all (4) batteries
I've accumulated are serviceable and 2 perform as new.
I'm told that the LS starter uses permanent magnets in it's
construction. Light weight yes but less 'snappy' in it's performance.
The NL starter is not much heavier and performs like the older, heavier
starters.
I'm still running with the LS - I have a robust 2 battery electrical
system where I can generally use just 1 for start but can go to 2 if it
won't go. But as cooler temps approach, I will be swapping it out for
the NL very soon.
There's lot's about this on this forum and the RV10 forum. Of course
the -540 is a bit bigger than the -360 but I'm sure it is even a factor.
I understand that Sky Tec will exchange it if it is unused but I don't
know.... I'll just have a backup starter on the shelf.
Bill "just made my annual Matronics contributribution because of stuff
like this" Watson
('saggy','bounce', and 'snappy' are trademarked technical terms limited
to use within the community of amatuer builders and tinkerers)
On 11/8/2011 5:33 PM, Peter Pengilly wrote:
> <peter@sportingaero.com>
>
> Bob,
>
> I would swap the starter out for an NL type (much better starter at a
> small weight penalty) and use the wiring that Sky-tec recommend. The
> weight saving from eliminating the starter solenoid is negligible.
>
> Peter
>
> On 08/11/2011 21:49, Bob Falstad wrote:
>> --> AeroElectric-List message posted by: Bob Falstad<bobair@me.com>
>>
>> Bob, et al,
>>
>> A friend of mine is building an RV-8A with a Lycoming engine bought
>> through Van's. It came with a Skytec starter, P/N 14912LS.
>>
>> Skytec recommends wiring it without a separate starter contactor.
>> Apparently, the solenoid that pushes the pinion gear out to engage
>> the ring gear also can act as the starter contactor. Van's shows
>> wiring this starter with a conventional, separate, starter contactor.
>>
>> Skytech shows wiring schematics/diagrams for each approach at
>> http://www.skytecair.com/Wiring_diag.htm (see Diagram A)
>>
>> What are the pros and cons of each approach? What experience have
>> listers had with each? (My friend does plan on using a push-to-start
>> switch, not a conventional key switch.)
>>
>> Best regards,
>>
>> Bob Falstad
>
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Subject: | Re: Wiring a Skytec Starter |
At 05:54 AM 11/9/2011, you wrote:
>
>I have the Vans supplied LS starter for the IO-540 on my
>RV-10. After initial experience with the LS starter and much
>consultation with other RV10ers, I plan to replace it with an NL type starter.
>
>Why? The LS gives me a 'saggy' kind of turnover. If the battery is
>anything but topped off, and OAT is 60+, it is likey to stall out
>before a full revolution. I can generally 'bounce' the prop and get
>it to turnover the 2nd time. It will turn it for a long time (don't
>ask) but that's a function of battery capacity.
Some years back, we explored the performance
difference between various offerings of starters
with the goal of explaining perceived performance
differences.
Back about 1990, the BIG thing was WEIGHT. The
bad dog in the pack was the Prestolite series
of starters which were retreads from 1940's
automotive. They were indeed heavy . . on the
order of 15-17 pounds.
OBAM aircraft owners were making successful
adaptations of modern, and much lighter starters
to the aircraft engine. The flying mags carried
a number of how-to articles.
About that time, one Bill Bainbridge at B&C
began mulling over the options and tradeoffs
. . . not for an adaptation . . . but a brand
new starter that would not only be lighter but
performs better. The lighter part wasn't
difficult. But performance was a little more
challenging . . . along with designing a casting
that could stand up to the occasional kick-back.
The B&C starters have always been wound-field
motors geared to run at higher than pinion
rpm by appropriate gearing. Recall that
HP = (torque X rpm). Allowing the motor
armature to run faster reduces the output shaft
torque required to produce the desired power.
Recall too that a motor has a sort of bell
shaped efficiency curve . . . zero rpm (stall
torque) is ZERO output power. Max rpm (free
running) is also zero output power. Someplace
between zero and max rpm on the performance
curves, the motor produces MAXIMUM power output.
The best performing starter would be the
beneficiary of trade offs for weight and
performance. Bill prayed over that product
for a couple years before he drug the first
production to OSH . . .I think it was about
1991.
Then came the field testing . . . and the
toe stubbing. Field tests were encouraging.
Reports from customers on performance were
always glowing. The downside of the lighter
castings was a vulnerability to poorly timed
mags and kickback. There was a significant
number of returns for broken castings. Sometime
early in the life of the B&C Lightweight, some
webs in the castings were strengthened.
The really cool thing was that the starter
was proven superior to any production starter
offered on ANY engine in Lycoming's stable
up through the 235 to 720.
Once market viability of a modern starter
was demonstrated, the wanna-be's had to
compete . . . on price and to a small extent
on weight. Unfortunately, I've never seen
a lucid comparison of performance of the
various starters. Some years ago, I wrote
to biggest players asking if they would loan
exemplar samples of their product line to
be placed on instrumented test stands to characterize
all significant performance points. Nobody
but B&C offered to make their product available
for such studies.
So here we are, 20+ years later with no
real comparative numbers that would assist the
cogent buyer in making their own return on
investment decisions.
Unfortunately, I've got so many things on my
plate that it would be pretty dumb to offer
to do that again. I did have an offer about 10
years ago from a publisher to finance such a
study. I agreed . . . then didn't hear from
them again. In today's economic state, prospects
for a similar endeavor are somewhere between zero
and none. Nonetheless, it would be a VERY
interesting study.
Bottom line is that there ARE starters which will
pretty much spin any engine at 100 rpm (3 blades
per second) with a reasonably maintained battery
and properly wired airplane. Bill and I drove to
some guy's hangar down in OK many years ago to
hook Bill's new 10 a.h. battery offering to a
IO-540 fitted with one of Bill's starters. We did
5, 15-second cranking cycles in a row. The 5th
cycle didn't not seem to be taxing the battery.
Did detect some slowing which was a product of
battery depletion and motor heating . . . but
the cranking rpm was till quite energetic.
Unfortunately, none of these starters will be
grouped at the lowest cost end of the price
spread. Further, wound field starters will always
perform best for cold-day and hot-start
scenarios.
There are some issues common to ALL modern
starters fitted with two-stage pinion-engage
contactors. See:
www.aeroelectric.com/articles/strtctr.pdf
This article does NOT touch on special
considerations for solenoid-contactor variations
such as the Sky-Tec multi-voltage, NL starters.
The Sky-Tec posting at
http://www.skytecair.com/Wiring_diag.htm
is an illustration of how many recipes
for success can pile up to confuse the OBAM
aircraft builder. Bottom line is that the
wiring first offered by yours truly and
published in B&C documents was based on a
study of starters, solenoids, styles of
starter switches, and commonality with the
vast majority of airplanes already flying.
It would be just fine for all but the specialty
starters . . . in fact, just fine for the NL
starters when the jumper is properly configured
for system voltage.
Another bottom line is that to my knowledge, there
are no incidents where a B&C starter owner found it
advantageous to swap out for any other brand
based on inability to perform-as-advertised on
any engine.
Bob . . .
Message 3
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Subject: | UPSAT Transponder |
Don,
The SL70 altitude readout is always based on an altimeter setting of
29.92. That is true of all transponders and you cannot change or vary
that setting. The readout on the face of the SL70 is the actual
altitude the transponder is sending to ATC. When ATC receives the
29.92 based altitude, it is converted to the local altimeter setting
for the area where you are flying. Thus, ATC should read the same
altitude as your correctly set baro altimeter.
If you set 29.92 in your baro altimeter, on the ground or in the air,
it should read the same as the indication on the face of the SL70. If
your baro altimeter is anything but 29.92, the SL70 SHOULD read
something different than the baro altimeter.
You said that ATC reports your altitude correctly as per your steam
guage, which tells me that your SL70 is working as advertised.
If ATC reports your altitude as something other than what your baro
altimeter is showing when set with the proper setting, you may have a
problem that can be corrected by adjusting the altitude encoder. That
is best done by a technician during the bi-annual altimeter
certification process.
Charlie Brame
RV-6A N11CB
San Antonio
-------------------------------------------------
>
> Time: 10:34:07 AM PST US
> From: DCS317@aol.com
> Subject: AeroElectric-List: UPSAT Transponder
>
>
> My UPSAT transponder Apollo Model SL70 gives Air Traffic Control the
> accurate altitude compared to my steam gauge altimeter and Chelton/
> Grand Rapids
>
> Technology units. However, the INDICATION on the face of the
> transponder
> is 300 feet off. Therefore not a problem with IFR, i.e., ATC gets
> the right
> altitude from interrogating the transponder (I've asked ATC numerous
> times), but I'd like the readout on the front of the SL70 to agree
> with my
> other altimeters.
>
> Any easy do-it-myself fix?
>
> Don
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