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Wiring a Skytec Starter

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bobair(at)me.com
Guest

Posted: Tue Nov 08, 2011 1:53 pm Post subject: Wiring a Skytec Starter

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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peter(at)sportingaero.com
Guest

Posted: Tue Nov 08, 2011 2:36 pm Post subject: Wiring a Skytec Starter

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:

 	  Quote: 	
		   



 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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Mauledriver(at)nc.rr.com
Guest

Posted: Wed Nov 09, 2011 3:59 am Post subject: 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:

 	  Quote: 	

 <peter(at)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:

> 

>

> 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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nuckolls.bob(at)aeroelect
Guest

Posted: Wed Nov 09, 2011 9:29 am Post subject: Wiring a Skytec Starter

At 05:54 AM 11/9/2011, you wrote:

 	  Quote: 	
		  



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 . . .

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