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Dual Lightspeed?
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CJohnston(at)popsound.com
Guest

Posted: Thu Oct 19, 2006 9:39 am Post subject: Dual Lightspeed?

Hey all –   

   

Sorry if this has been discussed already, but I combed the archives and couldn’t really find what I was looking for.  I’ve got a couple opinions privately, but thought I’d pose the question to the list.  I’m getting ready to order an engine, and originally I thought I’d go dual lightspeed ignition, but as I get closer, I’m starting to chicken out and am thinking of going single lightspeed / slick mag.   The aircraft is all electric, dual battery, and 2 alternators ( main, and SD-8 as standby).  Can I get a few people to weigh in?  

   

Thanks  

cj  

#40410  

fuse  

www.perfectlygoodairplane.net  (updated!!)  

   

--

randy(at)romeolima.com
Guest

Posted: Thu Oct 19, 2006 10:34 am Post subject: Dual Lightspeed?

With the batteries and backup alternator you are planning I'd  definitely NOT put in a mag. Klaus (Mr. Lightspeed) has a simple backup battery  schematic he provides if you don't want to do multiple buses. No question it's  better to have both plugs firing at the same time!

  

 Randy Lervold

 www.rv-3.com

 www.rv-8.com

 [url=http://www.rv-3.com][/url] 

 [quote]   ---

Tim(at)MyRV10.com
Guest

Posted: Thu Oct 19, 2006 10:41 am Post subject: Dual Lightspeed?

I don't see a problem with what you're doing either way.  I myself

chickened out, so I have one mag.  It seems as it isn't a real

bad compromise anyway, because my RPM drop is almost zero when

shutting off the mag, but is more when I shut off the Lightspeed.

The only negative I can say about running dual lightspeeds on

the IO-540 is this:



The cable that runs from the sensor under the flywheel/ring gear

is a pain in the butt to run, and it sits pretty close to

that wheel.  I can imagine that whole area could be somewhat

vulnerable to having things happen to it.  Since you use the

same sensors for dual lightspeed, I myself feel better having

something else in the back of the engine.  If I were running

2 P-Mags, I wouldn't have the same concern.  I'm absolutely

not saying there's something wrong with the arrangement that

needs to be changed...but it just isn't ideal from a reliability

standpoint....and in a manner that would fail regardless of

how many batteries or alternators you have.



I had dreamed of 1 lightspeed and 1 P-Mag, but I heard

a logical argument that due to differences in timing

curves between systems, this might not be a great idea.



You will love the lightspeed though, even if you still

have that one stinkin' mag. 



Tim



do not archive

Chris Johnston wrote:

[quote] Hey all –

 

  

 

 Sorry if this has been discussed already, but I combed the archives and 

 couldn’t really find what I was looking for.  I’ve got a couple opinions 

 privately, but thought I’d pose the question to the list.  I’m getting 

 ready to order an engine, and originally I thought I’d go dual 

 lightspeed ignition, but as I get closer, I’m starting to chicken out 

 and am thinking of going single lightspeed / slick mag.   The aircraft 

 is all electric, dual battery, and 2 alternators ( main, and SD-8 as 

 standby).  Can I get a few people to weigh in?

 

  

 

 Thanks

 

 cj

 

 #40410

 

 fuse

 

 www.perfectlygoodairplane.net <http://www.perfectlygoodairplane.net/> 

  (updated!!)

 

  

 

 --

mstewart(at)iss.net
Guest

Posted: Thu Oct 19, 2006 11:07 am Post subject: Dual Lightspeed?

I ran dual for 800 hours on one bat and one alt on an RV. Never worried one bit.  

Mike  

   

         

  

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Chris Johnston

 Sent: Thursday, October 19, 2006 1:38 PM

 To: rv10-list(at)matronics.com

 Subject: Dual Lightspeed?  

  

   

Hey all –   

   

Sorry if this has been discussed already, but I combed the archives and couldn’t really find what I was looking for.  I’ve got a couple opinions privately, but thought I’d pose the question to the list.  I’m getting ready to order an engine, and originally I thought I’d go dual lightspeed ignition, but as I get closer, I’m starting to chicken out and am thinking of going single lightspeed / slick mag.   The aircraft is all electric, dual battery, and 2 alternators ( main, and SD-8 as standby).  Can I get a few people to weigh in?  

   

Thanks  

cj  

#40410  

fuse  

www.perfectlygoodairplane.net  (updated!!)  

   

--

bcondrey

Joined: 03 Apr 2006
Posts: 580

Posted: Thu Oct 19, 2006 11:11 am Post subject: Dual Lightspeed?

Chris,  

   

I opted for dual LSE Plasma IIIs and have dual alternators and electrical busses.  The point that Tim makes is a valid one – the wiring from the crank sensor must be very well routed/secured.  With the dual system there’s a pair of cables but they are running together.  I suppose one could route one down each side of the engine to provide isolation in case of some sort of mechanical event that damage them.    

   

Bob  

         

  

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Chris Johnston

 Sent: Thursday, October 19, 2006 1:38 PM

 To: rv10-list(at)matronics.com

 Subject: Dual Lightspeed?  

  

   

Hey all –   

   

Sorry if this has been discussed already, but I combed the archives and couldn’t really find what I was looking for.  I’ve got a couple opinions privately, but thought I’d pose the question to the list.  I’m getting ready to order an engine, and originally I thought I’d go dual lightspeed ignition, but as I get closer, I’m starting to chicken out and am thinking of going single lightspeed / slick mag.   The aircraft is all electric, dual battery, and 2 alternators ( main, and SD-8 as standby).  Can I get a few people to weigh in?  

   

Thanks  

cj  

#40410  

fuse  

www.perfectlygoodairplane.net  (updated!!)  

   

--

Tim(at)MyRV10.com
Guest

Posted: Thu Oct 19, 2006 11:39 am Post subject: Dual Lightspeed?

I see Mike Stewart also replied that he sees no problems.

One thing to be aware of is that Mike probably has the

rear mounted hall effect sensors (or am I wrong, Mike?),

so it isn't the same as the IO-540 crank sensor mount.

Bob's got a good idea of separate routing.  I was also

*slightly* personally worried about the fragility of

the electronics up under that hub...and about the

what-if's during bad weather, or even lightning/static

discharge.  Again, I'm not saying "don't do it"...just

giving my rationalization.  I'm just as swayed to go

dual electronic some day...I just don't quite yet have

the nads required.  At least it runs great with just

one, or I'd be just diving right into it.



Tim Olson - RV-10 N104CD - Flying

do not archive

Condrey, Bob (US SSA) wrote:

 	  Quote: 	
		   Chris,

 

  

 

 I opted for dual LSE Plasma IIIs and have dual alternators and 

 electrical busses.  The point that Tim makes is a valid one – the wiring 

 from the crank sensor must be very well routed/secured.  With the dual 

 system there’s a pair of cables but they are running together.  I 

 suppose one could route one down each side of the engine to provide 

 isolation in case of some sort of mechanical event that damage them. 

 

  

 

 Bob

gorejr(at)bellsouth.net
Guest

Posted: Thu Oct 19, 2006 11:55 am Post subject: Dual Lightspeed?

Before you decide you might talk to some larger players in the engine building business like BPE.   They are building my engine and said they would not consider building it with either the Lightspeed or Lazar systems.  They have had to many problems.  They are building mine with 2 Bendix mags.  As an aside I have the Lazar on my mooney and have not had a problem.  There is supposed to be a new system coming out this next year that is superior to these 2 according to BPE.  Good luck!  Jim

[quote] 

 From: "Chris Johnston" <CJohnston(at)popsound.com>

 Date: 2006/10/19 Thu PM 01:38:15 EDT

 To: <rv10-list(at)matronics.com>

 Subject: Dual Lightspeed?

 Hey all - 

 Sorry if this has been discussed already, but I combed the archives and

 couldn't really find what I was looking for.  I've got a couple opinions

 privately, but thought I'd pose the question to the list.  I'm getting

 ready to order an engine, and originally I thought I'd go dual

 lightspeed ignition, but as I get closer, I'm starting to chicken out

 and am thinking of going single lightspeed / slick mag.   The aircraft

 is all electric, dual battery, and 2 alternators ( main, and SD-8 as

 standby).  Can I get a few people to weigh in?

 Thanks

 cj

 #40410

 fuse

 www.perfectlygoodairplane.net <http://www.perfectlygoodairplane.net/>

 (updated!!)

 --

jjessen

Joined: 22 Apr 2006
Posts: 285
Location: OR

Posted: Thu Oct 19, 2006 12:02 pm Post subject: Dual Lightspeed?

And, Tim, you have a standard mag, not a p-mag?  



John J



Do not archive 



--

bcondrey

Joined: 03 Apr 2006
Posts: 580

Posted: Thu Oct 19, 2006 12:16 pm Post subject: Dual Lightspeed?

FWIW, before making the decision to go single or dual I was having a

discussion at OSH last year with Klaus.  While talking Jon Johanson

(south pole fame) came by.  Turns out he runs a dual system!  Now, I

don't know which engine or pickups he had - 4 cyl can have either hall

effect modules that replace the mags or a crank sensor, 6 cyl only has

the crank sensor as an option.  I've noticed within the last few days

some chatter about the hall effect modules leaking oil after a few

hundred hours.  It was mentioned during that discussion that the crank

sensor was much more reliable although nothing quantitative to back it

up.



Bottom line: it's all about risk management.  In a dual LSE

configuration there's communication between the boxes which supposedly

provides some additional nominal improvement.



Following are the risks that I identified before making the leap along

with mitigation thoughts:

- all electric ignition; lose the electrons and you're a glider.  This

is managed by either a second battery wired as in the LSE instructions

or a dual electrical system.  Of course, having a single LSE and one mag

also eliminates this.



- crank sensor assembly as a single point of failure.  The assembly

actually contains 2 of everything and the only thing common is the

actual circuit board that the components are mounted on.  This assembly

(steel plate with circuit board mounted to it) is bolted to the

crankcase behind the crankshaft flange.  After the flywheel is in place

it's very well protected.



- wires from crankshaft sensor may be subject to damage.  As I said in

my earlier post, easiest way to mitigate this is to run one down each

side of the engine.  Biggest risk here is probably the alternator belt

breaking and somehow damaging the wire.  Highly unlikely that you'd have

damage to both if they had separate paths.



It would be easy to get REALLY carried away, but the reality is that

there are a lot of single points of failure (fuel lines after the valve,

control linkages, carb or injection system components, engine mech

failure, etc).  Bottom line: You have choices here - if dual electric

ignitions is going to cause you to lose sleep at night, go with a single

and a mag.



Bob



--

Tim(at)MyRV10.com
Guest

Posted: Thu Oct 19, 2006 12:38 pm Post subject: Dual Lightspeed?

Yessir, that's correct.



Tim Olson - RV-10 N104CD - Flying

do not archive

John Jessen wrote:

[quote] 

 

 And, Tim, you have a standard mag, not a p-mag?  

 

 John J

 

 Do not archive 

 

 --

flysrv10(at)gmail.com
Guest

Posted: Thu Oct 19, 2006 2:04 pm Post subject: Dual Lightspeed?

I know that you can rationalize anything you do and this is the way I rationalized my decision.  There are good reasons for electronic ignitions, they just were not good enough for me.



I decided against electronic ignitions for couple of reasons:

If you break down during your travel, no one can fix your system at the airport.  You will have to order parts and work on it yourself while being distracted from your intended trip.  This is my strongest objection against anything that is not known at airport shops.  I recently lost the alternator on my trip and experienced this personally.  Since I had to be at my destination the next day, I left the plane with a mechanic, ordered the alternator from Van, drove the rest of the trip and came back to pick up the plane after my business ended.



If you are looking for fuel economy, you will get it with mags at high altitude and high power.  Mag timing is  advanced to give you the best performance at your cruising speeds and altitude.  I am assuming that you are building this plane for something other than local short trips.



Mags, as short lived as they seem to be in service, can take a lot of beating and still continue functioning.  On one of my trips, I noticed a missed beat in my RV6.  I found that the mag seal was gone and it was full of oil, but it still worked.



I am not sure if Slick's Lasar system is reliable.  If so, that would be my choice.



Do not archive

 Rob



 



On Oct 19, 2006, at 1:38 PM, Chris Johnston wrote:

[quote]

Hey all –

 

Sorry if this has been discussed already, but I combed the archives and couldn’t really find what I was looking for.  I’ve got a couple opinions privately, but thought I’d pose the question to the list.  I’m getting ready to order an engine, and originally I thought I’d go dual lightspeed ignition, but as I get closer, I’m starting to chicken out and am thinking of going single lightspeed / slick mag.   The aircraft is all electric, dual battery, and 2 alternators ( main, and SD-8 as standby).  Can I get a few people to weigh in?

 

Thanks

cj

#40410

fuse

www.perfectlygoodairplane.net  (updated!!)

 

--

AV8ORJWC

Joined: 13 Jul 2006
Posts: 1149
Location: Aurora, Oregon "Home of VANS"

Posted: Thu Oct 19, 2006 7:10 pm Post subject: Dual Lightspeed?

Chris, this is an excellent discussion point but be sure and evaluate all the characteristics.  By reading today’s posts, most of the decisions were a “I follow the leader” mentality.  “I don’t know why but the crowd is moving towards the noise.  So I guess I should follow”  A responsible solution is to study the characteristics, ask experienced operators, weigh the pluses and minuses.  That means make a list.  

   

At this time the six cylinder P Mag is not yet an alternative.  It merits review.  The GAMI supplenator and PRISM are not yet to market.  The magneto and electronic ignition  systems are.  Do not limit your knowledge input.  

   

Which performs better at idle?  

Which assists in resisting Lead Fowling of your plugs?  

Which makes use of automotive plugs rather than aviation?  

Which is more reliable?  

Which is more cost effective over its entire life?  

Which is easier to maintain on the road when traveling distances from your maintenance base?  

Which produces more horsepower and performance in the range requests by the pilot?  

Which works better at altitude?  

Which does not change spark advance over the range of load, F/A temperature and rpm?  

What is Flame Front Propagation and why does it require a change in spark advance to maintain BMP?  

Which system will respond better to an alternative fuel to 100LL?  

Which one is less prone to failure and ensuing safety concerns?  

   

Your work is not done. Before you reach a conclusion, ask the pros.  You will likely get a choir of similar answers here which might not qualify the value of the answer enough.  This input has not yet been comprehensively tabulated.  In the lack of a conclusion on the subject. My source is Barrett.  The dyno says HP drop with dual electronics.  Research the why and the negatives before throwing out the baby with the bath water.  

   

John W. Cox  

#40600  

Do not Archive until all of the meaningful input is recorded.  

         

  

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Chris Johnston

 Sent: Thursday, October 19, 2006 10:38 AM

 To: rv10-list(at)matronics.com

 Subject: Dual Lightspeed?  

  

   

Hey all –   

   

Sorry if this has been discussed already, but I combed the archives and couldn’t really find what I was looking for.  I’ve got a couple opinions privately, but thought I’d pose the question to the list.  I’m getting ready to order an engine, and originally I thought I’d go dual lightspeed ignition, but as I get closer, I’m starting to chicken out and am thinking of going single lightspeed / slick mag.   The aircraft is all electric, dual battery, and 2 alternators ( main, and SD-8 as standby).  Can I get a few people to weigh in?  

   

Thanks  

cj  

#40410  

fuse  

www.perfectlygoodairplane.net  (updated!!)  

   

--

coop85(at)bellsouth.net
Guest

Posted: Fri Oct 20, 2006 4:03 am Post subject: Dual Lightspeed?

One last (probably not) consideration for you aside from the redundancy issues.  When I was looking at the Lightspeed options, I talked to Klaus and he indicated about 90% of the performance advantages are obtained with the first system and there is a limited performance increase by using dual electronic ignition systems.  Since I had not already put in the dual alternator/battery setup I opted for a Lightspeed/standard mag setup.  My only backup battery is in the Dynon EFIS I use as the standby instrument.  

   

Marcus  

40286  

60 hours and loving it  

         

  

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Chris Johnston

 Sent: Thursday, October 19, 2006 1:38 PM

 To: rv10-list(at)matronics.com

 Subject: Dual Lightspeed?  

  

   

Hey all –   

   

Sorry if this has been discussed already, but I combed the archives and couldn’t really find what I was looking for.  I’ve got a couple opinions privately, but thought I’d pose the question to the list.  I’m getting ready to order an engine, and originally I thought I’d go dual lightspeed ignition, but as I get closer, I’m starting to chicken out and am thinking of going single lightspeed / slick mag.   The aircraft is all electric, dual battery, and 2 alternators ( main, and SD-8 as standby).  Can I get a few people to weigh in?  

   

Thanks  

cj  

#40410  

fuse  

www.perfectlygoodairplane.net  (updated!!)  

   

--

gorejr(at)bellsouth.net
Guest

Posted: Fri Oct 20, 2006 4:55 am Post subject: Dual Lightspeed?

Talk to Rhonda at Barrett.  I think you might consider changing your mind about using these systems.  These folks are in the experience loop!  They deal with these issues daily.  Jim

[quote] 

 From: "John W. Cox" <johnwcox(at)pacificnw.com>

 Date: 2006/10/19 Thu PM 11:10:22 EDT

 To: <rv10-list(at)matronics.com>

 Subject: RE: Dual Lightspeed?

 Chris, this is an excellent discussion point but be sure and evaluate

 all the characteristics.  By reading today's posts, most of the

 decisions were a "I follow the leader" mentality.  "I don't know why but

 the crowd is moving towards the noise.  So I guess I should follow"  A

 responsible solution is to study the characteristics, ask experienced

 operators, weigh the pluses and minuses.  That means make a list.

 At this time the six cylinder P Mag is not yet an alternative.  It

 merits review.  The GAMI supplenator and PRISM are not yet to market.

 The magneto and electronic ignition  systems are.  Do not limit your

 knowledge input.

 Which performs better at idle?

 Which assists in resisting Lead Fowling of your plugs?

 Which makes use of automotive plugs rather than aviation?

 Which is more reliable?

 Which is more cost effective over its entire life?

 Which is easier to maintain on the road when traveling distances from

 your maintenance base?

 Which produces more horsepower and performance in the range requests by

 the pilot?

 Which works better at altitude?

 Which does not change spark advance over the range of load, F/A

 temperature and rpm?

 What is Flame Front Propagation and why does it require a change in

 spark advance to maintain BMP?

 Which system will respond better to an alternative fuel to 100LL?

 Which one is less prone to failure and ensuing safety concerns?

 Your work is not done. Before you reach a conclusion, ask the pros.  You

 will likely get a choir of similar answers here which might not qualify

 the value of the answer enough.  This input has not yet been

 comprehensively tabulated.  In the lack of a conclusion on the subject.

 My source is Barrett.  The dyno says HP drop with dual electronics.

 Research the why and the negatives before throwing out the baby with the

 bath water.

 John W. Cox

 #40600

 Do not Archive until all of the meaningful input is recorded.

 ________________________________

 From: owner-rv10-list-server(at)matronics.com

 [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Chris

 Johnston

 Sent: Thursday, October 19, 2006 10:38 AM

 To: rv10-list(at)matronics.com

 Subject: Dual Lightspeed?

 Hey all - 

 Sorry if this has been discussed already, but I combed the archives and

 couldn't really find what I was looking for.  I've got a couple opinions

 privately, but thought I'd pose the question to the list.  I'm getting

 ready to order an engine, and originally I thought I'd go dual

 lightspeed ignition, but as I get closer, I'm starting to chicken out

 and am thinking of going single lightspeed / slick mag.   The aircraft

 is all electric, dual battery, and 2 alternators ( main, and SD-8 as

 standby).  Can I get a few people to weigh in?

 Thanks

 cj

 #40410

 fuse

 www.perfectlygoodairplane.net <http://www.perfectlygoodairplane.net/>

 (updated!!)

 --

mstewart(at)iss.net
Guest

Posted: Fri Oct 20, 2006 6:22 am Post subject: Dual Lightspeed?

I had dual hall effects in my 6.

Have Direct crank in my 8.

Mike

Do not archive.

--

billderou(at)yahoo.com
Guest

Posted: Fri Oct 20, 2006 9:06 am Post subject: Dual Lightspeed?

I have a question for those familiar with Lightspeed (etc) ignition systems that I have been pondering for some time. Purchased a 25 SFOH engine with new mags and saw no good reason to upgrade. One mag was equipped with dual points "flash of sparks" and added a SlickStart in place of the old Bendix vibrator. It starts easily. 

   

  If you configure a system with Lightspeed and a Slick mag I would assume that the Lightspeed is firing at 25 degrees advanced up to 45 degrees while the Slick mag is always firing at 25 degrees. So what is happening to the force of the gas explosion?

   

  I cannot imagine that the Slick is contributing to the ignition if the Lightspeed is advanced beyond 25 degrees. Therefore, does the single, hotter Lightspeed spark create more explosive force than two mags firing at 25 degrees? Is this the root of the cruising performance gain?

   

  From  Lycoming, setting the mags at 25 degrees, I would assume this is optimum. What is gained when advanced beyond this point? How would the cockpit controlled variable timing be used strategically? Do we have firm evidence that a Lightspeed/mag configuration produces more horsepower than two mags?

   

  I understand the ease of starting argument but need more facts to understand the claim of higher cruise performance.

   

  Thanks,

  Bill DeRouchey

  billderou(at)yahoo.com (billderou(at)yahoo.com)

  flying

  do not archive

  



"Stewart, Michael (ISS Atlanta)" <mstewart(at)iss.net> wrote:

  [quote]--> RV10-List message posted by: "Stewart, Michael (ISS Atlanta)" 



I had dual hall effects in my 6.

Have Direct  crank in my 8.

Mike

Do not archive.

--

Tim(at)MyRV10.com
Guest

Posted: Fri Oct 20, 2006 9:58 am Post subject: Dual Lightspeed?

Bill DeRouchey wrote:

 	  Quote: 	
		   I have a question for those familiar with Lightspeed (etc) ignition 

 systems that I have been pondering for some time. Purchased a 25 SFOH 

 engine with new mags and saw no good reason to upgrade. One mag 

 was equipped with dual points "flash of sparks" and added a SlickStart 

 in place of the old Bendix vibrator. It starts easily.

  

 If you configure a system with Lightspeed and a Slick mag I would assume 

 that the Lightspeed is firing at 25 degrees advanced up to 45 degrees 

 while the Slick mag is always firing at 25 degrees. So what is happening 

 to the force of the gas explosion?

  


	


I'm not sure of the lowest lightspeed advance setting, but it may be

well below 25.  Remember that mags are set at 25 for the best

cruise setting.  The lightspeed can very depending on the

power setting, both MP and RPM.

 	  Quote: 	
		   I cannot imagine that the Slick is contributing to the ignition if the 

 Lightspeed is advanced beyond 25 degrees. Therefore, does the single, 

 hotter Lightspeed spark create more explosive force than two mags firing 

 at 25 degrees? Is this the root of the cruising performance gain?

  


	


I'm sure it's still contributing, just not as much.  You still get

the burn from the other side of the cylinder somewhat.  I don't think

there's any change in explosive force, just a hotter spark that ignites

quicker.  I think you will find there is an argument as to whether or

not there is a performance gain, or a loss...there are arguments on

both sides.



 	  Quote: 	
		   From Lycoming, setting the mags at 25 degrees, I would assume this is 

 optimum. What is gained when advanced beyond this point? How would the 

 cockpit controlled variable timing be used strategically? Do we have 

 firm evidence that a Lightspeed/mag configuration produces more 

 horsepower than two mags?


	


I think you can gain some fuel efficiency.  I would not recommend

the cockpit controlled variable timing.  I don't know that there is

any firm evidence of power increase with Lightspeed/mag.   I

do know that the Lightspeed equipped engines I've heard are

considerably smoother sounding than engines with only mags.

It's the fuel economy and smoothness that lead me to them.

Keep in mind that one of the other huge benefits is the lightspeed

will keep your plugs cleaner and let you use cheaper auto plugs.

In my previous plane, I was FORCED to clean the plugs...actually

remove them and pick out the lead and scale, every 25-50 hours,

even though I leaned aggressively.  On my new engine, it ran

smooth so I didn't pull the plugs until 70 hours...and then after

checking the front 4, I stuck them back in because they were

perfect, and skipped the rest.  Now, at 170 hours, it still

runs great, and soon I'll pull them again just to see how

it's looking.



 	  Quote: 	
		    

 I understand the ease of starting argument but need more facts to 

 understand the claim of higher cruise performance.

  


	


I wouldn't bet on the performance aspect.



Tim

[quote] Thanks,

 Bill DeRouchey

 billderou(at)yahoo.com <mailto:billderou(at)yahoo.com>

 flying

 do not archive

 

 

 */"Stewart, Michael (ISS Atlanta)" <mstewart(at)iss.net>/* wrote:

 

     

 

     I had dual hall effects in my 6.

     Have Direct crank in my 8.

     Mike

     Do not archive.

 

 

     --

LessDragProd(at)aol.com
Guest

Posted: Fri Oct 20, 2006 10:33 am Post subject: Dual Lightspeed?

Just my opinion:

  

 The hotter Lightspeed spark fires five (5) times during each combustion  stroke.

  

 The magneto "25 degree" spark advance is a single point setting that is  "always safe" for the harshest power setting.  It is NOT optimized for a  normal cruise power setting.

  

 Regards,

 Jim Ayers

  

 In a message dated 10/20/2006 10:08:16 AM Pacific Daylight Time,  billderou(at)yahoo.com writes:

  	  Quote: 	
		     (Stuff Cut)

   Therefore, does the single, hotter Lightspeed spark create more explosive    force than two mags firing at 25 degrees? Is this the root of the    cruising performance gain?

    

   From Lycoming, setting the mags at 25 degrees, I would assume this is    optimum. (Stuff Cut)

    

   Thanks,

   Bill DeRouchey

   billderou(at)yahoo.com (billderou(at)yahoo.com)

   flying

   do not archive

	


 

  

  [quote][b]

CJohnston(at)popsound.com
Guest

Posted: Fri Oct 20, 2006 10:36 am Post subject: Dual Lightspeed?

So since I’m the guy that started this and I’ve been reading everything I can about it all, I’ll chime in a bit…but I’ll qualify my input thusly – I’ve never built an aircraft before this one, and I’ve never owned one either.  I’ve also never worked on an aircraft engine in my life.  All of my info comes from my previous life of building drag racing engines of various flavors for fun.  and sometimes blowing them up.     

   

I too wondered about the effect of having 2 sparks happen at different times – and from what I can gather, the second (25 degrees BTDC)spark doesn’t do much of anything when the first spark is firing at full advance (around 45 degrees BTDC).  When the firing of both sparks is closer, I would suspect that (and I have no data to support this – just a guess) the first spark initiates the combustion at a more optimal time, and the second just contributes to the ignition of the remaining gas charge, and depending on the speed of the flame front, may not do much still.  According to lightspeed’s site, the spark is an uninterrupted 20 degrees in duration.  I don’t know what the duration of the magneto’s spark is (maybe someone else does?), but I imagine that at most RPMs and MPs, the lightspeed spark would happen at a more optimal time, and the magneto spark would sort of “chime in” upon reaching 25 deg BTDC while the lightspeed is still firing. At least conceptually this seems fine to me.    

   

In theory, I suppose that you could also run much leaner without roughness, because you can advance the timing to a point that you will still achieve a complete burn (or more complete I should say) of the fuel charge.  Again, in theory, you could lean and lean and lean, and advance (with manual control) and advance and advance, and get a very low fuel burn.    

   

To answer your question about advance, the 25 degree setting of a magneto doesn’t seem optimal.  I sort of look at it as a middle of the range value that works everywhere (at all altitudes – within reason of course) but isn’t really optimal everywhere.  In a race car, you’re tuning so that everything is optimal at WOT and nowhere else.  As long as the car will idle on the starting line without choking itself out, you’re good.  Of course you’re pouring unburned fuel into the exhaust pipes and the car wants to shake itself to pieces, but that’s ok.  I’d basically run mechanical advance only (no vacuum advance), and have it all in at something like 2500 rpms, if the redline was around 6500 or 7000.  If I remember right, fully advanced, it’d be somewhere in the neighborhood of 45 or 50 degrees at full advance, and somewhere around 25 to 30 degrees at idle.  Advanced timing and long spark duration is what you need if the rpms are up and the cylinder pressures are high.  Add nitrous, and everything changes (see the above note about things blowing up). In an aircraft where the air pressure changes, the mixture can be controlled from the cockpit, and WOT equals 2600 or 2700 rpms, 25 degrees of advance seems ok, but it seems to be a compromise that costs the engine efficiency as rpm and mixture changes.    

   

Again – I’M NO EXPERT.  Mostly, I’d get under the hood wind the engine up to full throttle, and turn the distributor back and forth til the thing ran right, then look at the number with the timing light and say “oh. I guess that’s the number.”  I realize that a bit more finesse is required when your life depends on the thing running right… J  

   

cj  

#40410  

fuse  

www.perfectlygoodairplane.net  

   

--

AV8ORJWC

Joined: 13 Jul 2006
Posts: 1149
Location: Aurora, Oregon "Home of VANS"

Posted: Fri Oct 20, 2006 4:03 pm Post subject: Dual Lightspeed?

Flame front propagation is a fascinating topic.  F/A mixture is hotter near the exhaust valve that a comparatively cooler intake valve. Heat is a catalyst for combustion.  If it is a charged carbon deposit and ignites a mixture at other than the required timing it gets its own name – Detonation.  If the event happens before the piston is ready to provide the power-stroke and it is before the exalted event, it is called PRE – ignition.  Read the GAMI site.  The theory is they both meet in the middle in perfect harmony.  Distributor, Mag timing and Electronic timing and all things spark related need to change with the change of engine load and rpm.  A finite setting does not enhance this phenomena.  

   

The phrase Optimum is a mis-leader in that it is the better of a poor trade off.  PRISM will address this need for a changing advanced spark curve.  One of the vulnerabilities of Mags is they are Primeval – Brain Dead simple and reliable at a single setting throughout a range of performance requirements.  

   

Everyone building should make their personal decision based on research rather than popularity of the moment.  

   

John Cox  

         

  

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Bill DeRouchey

 Sent: Friday, October 20, 2006 10:06 AM

 To: rv10-list(at)matronics.com

 Subject: RE: Dual Lightspeed?  

  

     

I have a question for those familiar with Lightspeed (etc) ignition systems that I have been pondering for some time. Purchased a 25 SFOH engine with new mags and saw no good reason to upgrade. One mag was equipped with dual points "flash of sparks" and added a SlickStart in place of the old Bendix vibrator. It starts easily.   

    

   

    

If you configure a system with Lightspeed and a Slick mag I would assume that the Lightspeed is firing at 25 degrees advanced up to 45 degrees while the Slick mag is always firing at 25 degrees. So what is happening to the force of the gas explosion?  

    

   

    

I cannot imagine that the Slick is contributing to the ignition if the Lightspeed is advanced beyond 25 degrees. Therefore, does the single, hotter Lightspeed spark create more explosive force than two mags firing at 25 degrees? Is this the root of the cruising performance gain?  

    

   

    

From Lycoming, setting the mags at 25 degrees, I would assume this is optimum. What is gained when advanced beyond this point? How would the cockpit controlled variable timing be used strategically? Do we have firm evidence that a Lightspeed/mag configuration produces more horsepower than two mags?  

    

   

    

I understand the ease of starting argument but need more facts to understand the claim of higher cruise performance.  

    

   

    

Thanks,  

    

Bill DeRouchey  

    

billderou(at)yahoo.com (billderou(at)yahoo.com)  

    

flying  

    

do not archive  

    



 

 "Stewart, Michael (ISS Atlanta)" <mstewart(at)iss.net> wrote:  

  [quote]  

--> RV10-List message posted by: "Stewart, Michael (ISS Atlanta)" 

 

 I had dual hall effects in my 6.

 Have Direct crank in my 8.

 Mike

 Do not archive.

 

 

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