Hey, I warned you that was my biased opinion! ;-)
OK, thank you for the opportunity to discuss my two pet subjects: aircraft
engine ignition and certification thereoff..
First of all, one of my first job was reliability analyst engineer. From
that experience, I have retained that all technologies fail. Bad design
helps to fail faster, but no matter how well you design and manufacture,
some technologies have inherent limitations. It is bad practice to
compensate low reliability with high redundancy and heavy maintenance. It
is better practice to switch to a better technology. That is what the
automotive industry did. That is not what the light aircraft industry did,
because market pressure and manufacturing quantities are much lower.
Personally, I do not trust high speed rotating electrical contacts, which
is basicaly what magnetos and distributors are. Especially when they have
been designed in the 1930's. But I do not trust very fancy electronics
either, and software, even less. This is why I am so happy with
contactless, solid state electronics, which I feel is a good trade-off.
The failure mode of an electronic ignition is usually what we call in the
trade "catastrophic failure", meaning that it is both total and sudden.
So, yes, that is less comfortable that your mags giving you a rough
running engine. But the failure rate of magnetos is much higher, and their
performance as an ignition system is much lower. Not to mention the costs.
So, that's a choice.
As far as redundancy is concerned, I did not design my electronic ignition
system. It came with the KR2 when I bought it, a few years ago, in South
Africa. It was partially redundant, with two pick-ups, but only one set of
coils and spark plugs. I decided to make it fully redundant, because I
knew that if I had to relocate somewhere else (which eventually happened)
, it would be easier to convince the inspectors if the system is fully
redundant. So, certification issue again.. My personal opinion is that one
ignition is good enough. I have got only one carb and one propeller, so I
could live with one good ignition. But in any case, electronic ignition
requires a highly reliable electrical system, ad this is where I tried not
to goof. Still from my experience as a reliability engineer, I took great
care not to have dormant failures (meaning a failure that comes
undetected). I want to make sure I have ten solid minutes ahead of me to
make a precautionary landing.
What is true for me is true for the aircraft manufacturers. Jeff Scott
says:
"However, the certification process is there for many more reasons than to
dig $$ out of your pockets to propagate the use of antiques"
"The FAA does not require the use of magnetos in certified aircraft. For
certification purposes, it does require that if the ignition system is
dependant on battery for power that there be a minimum of 30 minute
reserve with part of that time under a normal electrical load. So why is
it that Cessna and Piper are still using magneto fired engines? OK,
Cirrus is a new company doing cutting edge work even using electronic
FADEC controls and glass cockpits. So why are their engines magneto fired
as well? Think about it. I'm sure their engineers have.
The answer is: the market. Face it guys: aircraft engines are very
expensive, very inefficient and very unreliable as compared to car
engines. Light aircraft lag way behind cars as far as technology is
concerned. Cessna and Piper build aircraft that were designed in the
1950's at the best, and Lycoming and Continental make engines that were
designed roughly at the same period. That is the reason why a $ 250 000
aircraft does not have electronic ignition, fuel injection, airbags, ABS
brakes, air conditioning, and all the nice things that any $ 15 000 car
would have. Most brand new aircraft even come without a decent safety
belt, for Pete's sake!
Cirrus had a lot more ambition for their aircraft, but they ended up
cutting corners, because of the high cost of certifying new solutions. The
cost of certification is not only high, it is also unpredictable. If I
remember well, Cirrus's certification budget was in excess of 50 MILLION
dollars. They made clear at a point that they wished for a better engine,
but they could not find one that could be certified quickly and cheaply
enough.
I once saw a brand new Lycoming engine with a very strange ignition
system: it had one set of plugs on magneto, and the other set on
electronic. Only in aviation can you find such strange things...
Well, enough preaching. The bottomline is I do have a proven electronic
ignition solution for VW engines that several times cheaper than magnetos,
very easy to build, and maintenance free. Anybody interested, just E-mail
me. I will be happy to send pictures, schematics, and explanations.
Anybody wanting me to revert to magnetos, don't waste your time. I'm
beyond redemption, and I'm too broke for the expense anyway. ;-)
And anyway, my next engine will simply have no ignition system at all.
'cause it will be a Diesel.
Serge Vidal
KR2 "Kilimanjaro Cloud"
Paris, France
"robert glidden" <glid...@ccrtc.com>
Envoyé par : krnet-boun...@mylist.net
2005-02-23 05:24
Veuillez répondre à KRnet
Remis le : 2005-02-23 05:34
Pour : "KRnet" <kr...@mylist.net>
cc : (ccc : Serge VIDAL/DNSA/SAGEM)
Objet : Re: Réf. : KR> Electronic Ignition
I'm am not a fan one way or the other,but how can you in one paragraph say
mags are bad and always go out thats why they run dual mags on certified
aircraft.And then in a later paragraph say you have found a better system
that consist on dual (two) electronic systems.Having worked with both
system
I will say the one hugh advantage to a mag on a car or airplane in the do
not usually go out without giving some type of warning,by that I mean the
engine runs ruff or misses out noticably.On the other hand when your
electronic ignition goe's out it just stops working.You can run as many
electronic systems as you want,but if your alternator or batter goe's out
I
hope the other is working good at 8000 ft above mother earth.And if your
going to tell people they are better the mags why not run one ignition.Not
trying to stir anything just curious...Bob
Being a
geared system, they are, by essence, very unreliable. This is the very
reason why there are two of them on an aircraft
I
On my 2.0 liter Type 4 VW, recently replaced by a 2.4 liter Type 4 VW, I
run a fully dual redundant electronic ignition system. This consists of
two solid state electronic ignitions, salvaged from 1980's motorcycles.
.
"Robert L. Stone" <rsto...@hot.rr.com>
Envoyé par : krnet-boun...@mylist.net
2005-02-22 18:51
Veuillez répondre à KRnet
Remis le : 2005-02-22 18:53
Pour : "KR Builders Pilots" <kr...@mylist.net>
cc : (ccc : Serge VIDAL/DNSA/SAGEM)
Objet : KR> Electronic Ignition
Netters,
I have heard that the modern electronic ignition system is more
reliable than the conventional two magneto set-up in all aircraft engines.
Assuming this is true, opinions from any of you who are knowledgeable in
this area would be welcome. Also does anyone know where if at all an
electronic ignition to use on a VW engine is available.
Bob Stone, Harker Heights, Tx
rsto...@hot.rr.com
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