|
Message
We are certainly in agreement, Al.
Substantial risk is involved in any alternative engine roll-your-own.
No doubt a proven FWF package would mitigate the risk to a certain extent.
I agree that other than a seat-of-the-pants
feel that my subsystem's are robust (in the sense of avoiding failure), I have
no quantitative measure of my system's "safety Margin".
I know hot days, long taxi, and
MogGas are combinations that move me closer to that edge with my fuel system ,
so I try to avoid at least 1 of the 3 if not all. So I am intrigued
by your 0-10 scale. Clearly 10 is tough (if not impossible) to
achieve. Do you have one worked out already for the fuel system (appears
you do), how about our other subsystems?
Would certainly be interesting for
everyone to take the 0-10 exam on their system and report the results of the
assessment. Perhaps we might find those above a 5 and give them some
careful study.
We do have a "Best Practices" Web site which
does contain some of our discovered "good ways" as well documentation of some of
the "not good ways". But, no quantitative assessment criteria that I am
aware of.
Ed
----- Original Message -----
Sent: Wednesday, May 24, 2006 10:52
AM
Subject: [FlyRotary] Re:
Rationalization
As always, I'm so impressed with your ability to face the risks Ed. That
is such a key item. I too pursue high risk activities and find it's essential
to assume I will fail. This motivates me to seek my oversights, prove systems
out instead of assume they will work, etc.
I agree there is great value to being able to standardize a few of the
engine systems. Some sort of FWF package could achieve that. More than any
other engine system, you guys have your hands on a lot of different
components. That really increases risk. So if there were a few standard
systems, risk would drop.
There is one very important characteristic that I seldom see you
guys discuss. "How do I achieve safety margin?". Example: When I
build my fuel system, if it fails immediately, we would rate that as a 0
on scale of 1 to 10. But if it can't fail when I operate under extreme
negative conditions, then it would be rated a 10. So a 10 is fuel system
unaffected by intense heat, like sitting on ramp at 120f for 4 hours.
Unaffected by use of ethanol. Unaffected by blown fuse. Etc. etc. This concept
is to important. How far is your system from the failure point? Many of you
are flying with fuel systems that rate a 3 on scale of 0 to 10. Meaning it
often will work ok, but under certain conditions it will fail. Your plane is
sitting right next to a guy who has a 10 fuel system, yet neither of you are
aware. Both have good intentions, both want safety. Just totally unaware.
A key item is finding ways to measure(using numbers, not
speculations) how close your system is to failure. Then taking action to
move it as far as possible toward a 10. If you had one guy doing this with
fuel sys, exhaust sys, electrical sys, cooling sys, etc, then you are
half the way there. The other half of that solution involves how you prove to
others that you have a 10. Most of us have NOT been exposed to
success patterns. We are unaware of the need to add safety margin. We build
our fuel system, fire it up, then say "Yahoo, it works! I'm done.".
I've had years of experience working will failure patterns, pursuing
success patterns. I find it fascinating that all systems migrate to borderline
failure point if we use our natural method of doing things. It takes effort
and facts to build in safety margin. Off the soap box.
I agree in part about the reliability
FWF, Rusty. However, if you read the accident reports, you will find
that FWF reliability is just as bad a problem with Lycomings in RVs.
Something like 20-30% of all homebuilt crashes happen during take off and
are fuel related and as you know the vast majority are Lycoming
powered. I don't know what our percentage would be but I would bet in
the same ball park.
I am aware of two fatalities during
early stages of flight with Rotary's and a third one that occurred with a
rotary powered RV years after its first flight and after several hundred
hours of flight. So that's three I am personally aware of. Last
time I counted there were something like 30+ rotary powered aircraft (that I
could find and that was several years ago), so even if there were no
more than that number, that would put us in the 10% fatality range.
Could be higher, could be lower, but I would say in the same ball park as
the overall Homebuilt accident rate - NOT that is good by any
stretch.
I do agree that we need to do better in
that area. However, as YOU know we are all experimenters - willing to
try a different approaches. I think its very clear that should you
follow Tracy's, Bill Eslicks, or (heaven forbid)even my approach - or any
FWF configuration that has been proven over several hundred hours or more of
flight - the odds are good you won't have a failure. But, being
experimenters, we want to try out our own ideals or are forced by our FWF
configuration to try a different approach - which as we all
know do not always work out successfully.
We possibly could standardize on a
"safe" configuration - but then we would no longer be "experimenters"
{:>)
Ed
----- Original Message -----
Sent: Monday, May 22, 2006 6:11
PM
Subject: [FlyRotary] Re:
Rationalization was [FlyRotary] Re: Questions from a potential
rotaryphile
However, I
believe, there is plenty of objective evidence that says the
rotary is comparable or better than the Lycoming in just about any aspect
you want to consider.
Hi Ed,
I would agree with the above statement, but
unfortunately, the one key area where the rotary clearly hasn't
demonstrated superiority is "FWF reliability". The rotary
group has had way too many failures in the past couple
years, and this needs to be the area we work on. Most of
it has been silly things, and I'm certainly ashamed for
my contribution to the problems.
Even the Aviation Sport article
supports that conclusion
Does
anyone have an electronic copy of this article they could send me? I
guess I'm the only one who hasn't read it.
certainly cost less (even if you
have to buy engine parts new), etc., etc. So no doubt there is
some rationalization- but I'm not certain over what?
I would argue cost, and
have in the past. I would (actually have) bet real money that
the $21k Lyclone I just installed on the RV-8 will work out to
be cheaper than a rotary engine installation over the few years
(at least) that I hope to fly this plane. This factors in resale of
course.
IF somebody would take the
rotary and produce a reasonably price FWF kit, I believe you would find
the rotary installations would expand exponentially. Most folks are
understandably a bit daunted by the challenge of designing and
putting that all together on their on.
Amen brother!!! This is
certainly what would need to happen. Powersport made a great
engine installation, but at such a high price that not too many people
bought it. If someone like Eggenfellner would make a rotary package,
it would be expensive, but from a name that people know (whether they can
spell it or not), and trust. I would certainly hope that people
would see the value of a rotary over the Subaru given the same price, and
FWF producer.
Better get started on that
article now :-) Actually, I was wondering if the rotary group could
put together it's own fly-off between similar planes. It would
have to be well documented, but we have enough engineers here to make sure
of that. Heck, in the not too distant future, we should (
<--- key word <g>) have a 2 and 3 rotor RV-8 to test against
my Lycoming.
Cheers,
Rusty (T-minus about 53 hours
until I'm back
home)
PS, can't wait to hear how
the 500HP Lancair
flies!
-al wick
Artificial intelligence in
cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on
engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk
assessment, Glass panel design
info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
|