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I think you just got unlucky. But...
The stock water pumps are not really intended for extended high RPM operation. Racers get "underdrive pulleys" and related belts which reduce the speed at which the accessory drive belt turns. This will slow the alternator and water pump as well as anything else you have on there (if you have an air pump or air conditioner). Slowing the water pump can actually improve cooling performance since it is turning much faster than it is designed to turn. I would highly recommend these.
On Mon, Apr 13, 2009 at 5:14 PM, Mike Perry <MKPerry99@cfl.rr.com> wrote:
Here is another to add to the list. "Water
pump failure". At 18 hours I noticed my water pump leaking
through the weep hole. This was a slow leak
that I would have to add coolant after a two hour test flight.
Since this was the original pump on my 1986 13B I
figured it was well past due considering it was 20 years
old. When I bought the new one at the Mazda
dealer the parts department said they could only get
rebuilds.
This last Saturday at 72 hours on the engine I took
off for my second test flight with a new IVO Magnum
adjustable prop. Excellent acceleration and
better rate of climb than my home made composite prop.
However, with the old prop and 2.17:1 PSRU I was
never able to get much over 5000 rpm. With the old
prop I would take off and climb to 1000 AGL then
reduce power to let temp cool down to below 200 degrees.
It would hit about 220 in the climb. Oil
temps have always been below 190.
At medium pitch on the IVO I was close to 6000 rpm
and by the time I reached pattern altitude on both
the first and second flights it hit 230. On
this second flight I did my usual reduced power and let it
cool
down as I flew out to my test area over the sod
farms. After 15 minutes of flight time I set power to 5000 rpm
and played with the prop control then worked my way
up to 5500 rpm. At this point I am 20 minutes into
the flight when I notice my temps are back at
230. I reduce power to 4000 rpm and check oil temp is
still at 180-190. I turned back to the
airport but the temp is still climbing. Reduced power to 3500 and
about
90 knots. GPS says 10 minute ETE and now the
oil temp is at 200.
I got a straight in to Rwy 33 and when I cut the
power on final I had 260 on the water pump outlet sensor,
which was probably just reading hot air and 230 on
the pump inlet sensor. Oil temp hit a hi of 230. The engine
never missed a beat the whole time. When I
got off the runway and shut it down I had a trail of coolant
behind me. I pulled the cowl off and had
coolant all over the bottom cowl where my over flow tube dumps out
but no sign of hose or fitting failures.
Sunday after letting it cool overnight I swung the prop through and it
still
has good compression from the sound of it. I
started to fill up my expansion tank and after about 2 quarts of
coolant I could hear it draining back into my drip
pan. The coolant was just running out the weep hole on the
water pump.
I would like to know if anyone else has
had problems with water pumps and any comments.
Mike Perry
N981MP
Long Ez
----- Original Message -----
Sent: Monday, April 13, 2009 9:16
AM
Subject: [FlyRotary] Re: forced
landings
Dave,
I have decided to take Al's suggestion and limit the criteria
for the spreadsheet to basically include any in-flight system failure which
interrupts the planned flight and results in a premature landing. Based
on this, I will add #3 & #4 as well as the one resulting from a
ruptured coolant hose.
Mark S.
Mark, And did you get these? Added by me and John Slade under the
wrong thread title:
On Sun, Apr 12, 2009 at 5:15 PM, John Slade <jslade@canardaviation.com> wrote:
Here's a few for the list, Mark,
1. Stock turbo bearings collapsed
& took out apex seal. Flew home at reduced power.
2. Fuel
filer (sinstered bronze) looked clean but was restricting fuel flow. Flew
home on other tank.
3. Bad / intermittent contact on ignition
timing sensor made engine run rough. Landed normally and
repaired.
4. Turbo hose blew off on take-off. Returned to land
at reduced power.
John
------
Been there, done
that. (the blown-off intake hose)
Also:
I have burned out 2 turbos. The first caused precautionary/urgent
landing at an airport pending shutting off fuel flow to the turbo. The
second, I flipped a turbo oil shut off switch and flew 1000NM to get
home.
Had a fuel pump die in flight, switched to the other and kept
flying.(soft failure)
I had a bad injector enable switch causing rough running during some
phase one flying (after major change)... landed normally
Forgot to re-connect fuel return line in engine bay after doing
some work. dumped a couple gallons of fuel onto the running engine
until I smelled gas and shut down the engine.. (never left the parking space
- but it could have been really bad.
Cracked alternator mount bracket found on pre-flight during phase
one testing. Would have lost cooling and alternator if it happened
now.
PSRU sun gear pin broke from a backfire during run-up. Was
able to taxi back but would not have been able to fly.
This is
good - broke a coolant line in flight and smelled coolant... landed at
nearby airport and taxied up to restaurant with steam spewing out of the
cowl. Me and my buddy calmly walked into the restaurant and had
breakfast. Afterward, we borrowed some tools and fixed the coolant
line. Went back into the restaurant to ask for 2 pitchers of water to
put in our plane. Continued ski trip to Mammoth. The end.
Thanks
Bill,
With the addition of Bill's exciting adventure, and one of
my own, we're up to 18 incidents in the database. These last two,
along with Ed's brake fire, and an oil coolant rupture, totals four
incidents involving fires during ground operations. Hopefully,
everyone carries at least one fire extinguisher in their
airplane.
Mark S.
One other thing to watch out for -- This
occurred during ground testing, but if it had happened in the air it
would have been a forced landing.
From my post of Feb. 8
Well, I haven't heard of this happening
before -- I was ground running my engine to tune it with the EM-2
and EC-2. Ran for almost an hour, at various rpm's to change the
manifold pressure and tweak the settings. Cooling working well, I had
the top cowling off to allow good exit area since I was tied down.
Coolant pressure about 14 psi as reported on the EM-2.
Engine was running good, took it up to
~6000 rpm swinging a 76x76 Catto prop, when suddenly there was steam and
fluid on my windshield. Shut it down by killing power to the EC-2.
Coolant everywhere.
Got out and looked to diagnose the problem
-- NOT my plumbing. A FREEZE PLUG in the iron housing had blown
out. Rapid coolant dump.
Secondary effect -- Since I shut down
suddenly from full tilt, either the proximity of the cowl to the
exhaust, or possibly some of the coolant on the exhaust started a small
fire on my cowl. Put it out with extinguisher, but corner is
charred.
Now in repair mode.
--------------------------
Update since this incident: All
freeze plugs (7) on the engine have been replaced by Bruce Turrentine,
and he has inspected the engine. I am currently reinstalling it and
getting ready for more tuning exercises.
Bill Schertz
KIS Cruiser #4045
N343BS
-----
Original Message -----
Sent:
Sunday, April 12, 2009 1:51 PM
Subject:
[FlyRotary] Re: forced landings
Charlie, That's a very good point. I'm
trying to stay away from assigning a "cause" for whatever happened
because I don't have all the facts. I have a field that says
"Explanation of Failure". Hopefully, we can make statements as
you suggest. Sometimes, even the FAA gets it wrong, like the
time they attributed the engine failure to the builder removing the
oil injection pump. Also, I doubt that we could all agree on a
"single cause" for each failure. Maybe it is due to a poor weld,
or wrong choice of material, or improper strain relief, or lack of
heat shielding, or a little of each. What I hope to accomplish
is to point out areas where we need to be more careful on how we
design a particular part or system.
List is at 16
now. Anyone else want to add a "dark and stormy night" story to
the list?
Mark
I think that it's just as important to understand the real
cause of the failure. In the case of the plastic fuel flow sensor,
it's highly unlikely that use of the plastic sensor caused the
failure; it was the use of plastic in the wrong area without any
protection. The homebuilder's knee-jerk reaction is to say 'no
plastic sensors because that one melted', even though there are tens
of thousands of the same sensor in use in boating, a much more
severe environment.
Kind of like the canard builder who tried
to put fuel in a wing built with fuel-soluble foam. Obviously, it
failed, but only because of the wrong application of products, not
the products themselves.
Charlie
From: al wick <alwick@juno.com>
Sent: Sunday, April 12, 2009
10:13:00 AM
Subject: [FlyRotary] Re: forced
landings
Absolutely excellent Mark. I'd encourage you to get the year the
incident occured too. That will be your proof of reduced risk from
things like this newsgroup.
Avoid the black and white approach: forced landing or not forced.
Because all things are shades of grey. Instead rate the severity. So
it's a 10 if the guy had to glide, it's a 1 if he did
precautionary landing. If you also explain what happened, then a
reader can easily tell you were objective in your rating.
The final piece is about how many flight hours, first flights
there were. Each year there are more engines flying, so way more
likely you will hear of incident. A wild assed guess is ok, if you
just base the guess on some facts. For example, you could check faa
database and find 100 planes registered with rotary engine in 2005.
You can guess that equals 70 hours each. Even though it's a wild
assed guess, it will still be excellent predictor of change over
time. Each year you have the same "error". So your numbers WILL
reflect improvement.
More important than anything. If you can force your self to say:
"That same failure will happen to me". Particularly if you can look
at "contributing factors". Then you can dramatically reduce personal
risk. Good example: We had that guy that installed plastic fuel flow
sensor in fuel line. It melted, he died. Tracy just reported hot
exhaust caused fuel to boil out of carb. These have the
same root cause. You don't want to say:" I have efi, can't
happen to me". You want to say:" I expect heat will cause a failure.
I'll put a thin ss shield here, with a bit of fibrefax glued to
back. So if muffler fails, it won't affect....."
Every forced landing had 10 little incidents in the past that
preceded it. Your risk isn't some new cause. It's 1 of those 10
incidents that you rationalized away, instead of saying:" that will
happen to me too."
Good stuff.
Subject:
[FlyRotary] Re: Gary Casey was [FlyRotary] Re: Rotary
Engines
Date: Sun, 12 Apr 2009 06:45:24 -0500
Mike,
Has anyone ever tried to document the rotary incidents
resulting in a forced landing?
Here's what I recall from
memory, so it likely is missing a
few;
3 forced landings due to
ruptured oil coolers
1 forced landing due to
apex seal coming out of its slot (rotor out of
spec)
1 forced landing due to improper
assembly of engine (seal wedged between rotor & side
housing)
1 forced landing on highway due to
catastrophic overheating of engine
2 forced
landings (one fatal) due to probable fuel system design flaw
1 forced landing on highway due to ingestion
of FOD.
There were a few others, such as turbo
failures which allowed for continued operation at reduced power, so
we may or may not wish to include those here.
While a
number of these incidents date back quite a few years, and we have
made excellent progress, it says to me that we still have room for
improvement in the peripheral department. The good news is
that out of all of the incidents listed above, none of them were
caused by a true engine failure. That's where the rotary has
really earned my respect as a viable a/c engine.
Pay
attention to the details!
Mark S.
This has been an interesting thread.
In the end, it doesnt really matter how many "major" parts you
have - even a minor failure can bring you down. While I believe
the basic rotary engine itself is more fault tolerant than a
recip, the peripherals used in the typical rotary install are a
lot more complex than a typical recip install. Since we rotary
fliers dont have the benefit of 70 years worth of experience
flying behind the typical LyCon farm implement I think overall our
odds are considerably worse. Comes down to how well an individual
engineer's his installation and there is a tremendous amount of
variation here.
The dependence on electronics in the
typical rotary install is a good example. I may be a
little sensitive to this issue since I've been trying to find
an intermittent glitch (2 times in 22 hours of engine
testing).
Mike Wills
RV-4
N144MW
-----
Original Message -----
Sent:
Saturday, April 11, 2009 7:31 AM
Subject:
[FlyRotary] Gary Casey was [FlyRotary] Re: Rotary Engines
Good
analysis and logic, Gary.
You’d
make a good addition to the “rotary community”. I have
noticed over the 10 years I have been flying my rotary powered
RV-6A that the problems have decreased considerably, the success
rate and completion rate has gone up and first flights are now
occurring without significant problems – even cooling is OK
{:>). I believe most of this improvement can be
attributed to folks sharing their knowledge, problems and
solutions with others - such as on this list.
I know
that fewer parts count is often touted as one of the rotary
benefit – and while it is true that the part count is lower, the
most significant thing (in my opinion) is not only does the
lower part count help reliability (if it is not there – it can
not break), but if you look a the design of the eccentric shaft
(for example) you notice the absence of the jogs in a typical
crankshaft and their stress points. The thing is over 3”
in diameter at some points and does not have the same inertia
loads born by a piston crankshaft. The parts that are
there are of very robust design. Finally, the rotary is (I
believe) more tolerant of damage and tends to fail “gradually
and gracefully”, it can take a licking and keep on ticking as
the old saying goes. Only extended time and numbers will
provide the true MTBF for the rotary, but I believe it looks
very promising.
Failure
of rotary engines are extremely rare, but unfortunately, as with
many alternative engine installations, auxiliary subsystems such
as fuel and ignition frequently being one-off designs have been
the cause of most failures – with probably fuel the prime
culprit. The good news is that for some platforms (such as
the RVs) we have pretty much established what will make an
installation successful. The Canard crowd is fast
approaching that status with their somewhat more challenging
cooling requirements being over come.
Having lost a rotor during flight due to putting in high
compression rotors with worn apex seal slots worn beyond specs
(found this out later – my fault for not being aware of this
spec limit and checking it) which led to apex seal failure and
consequence lost of most of the power from one rotor, I was
still able to maintain 6500 MSL at WOT and fuel mixture knob to
full rich – flowing 14.5 GPH – a lot of it undoubtedly
being blown through the disabled rotor. Flew it back
60 miles to a suitable runway and made a non-eventful
landing. There was a small increase in vibration due
to the power strokes no longer being balanced, but nothing bad
and you could still read the needles on the gauges. Other
folks have had FOD damage to a rotor and also make it to a safe
landing. Two folks lost cooling (one loss of coolant fluid
, one lost of water pump) and while they did cook the engines,
both made it back to a safe landing. So all things
considered, I think the rotary continues to show that if the
installation is designed properly, it makes a very viable and
reliable aircraft power plant.
Failure
of rotary engines in aircraft are extremely rare, but
unfortunately, as with many alternative engine installations,
auxiliary subsystems such as fuel and ignition frequently being
one-off designs - have been the cause of most failures.
The good news is that for some platforms (such as the RVs) we
have pretty much established what will make an installation
successful. The Canard crowd is fast approaching that
status with their somewhat more challenging cooling requirements
being over come.
My
rotary installation cost me $6500 back in 1996, the primary cost
being a rebuilt engine $2000 and the PSRU $2900. I have
since purchased a 1991 turbo block engine from Japan for $900
and rebuilt it myself for another $2200. My radiators (GM
evaporator cores) cost $5.00 from the junk yard and another
$50.00 each for having the bungs welded on. So depending
on how much you buy and how much you build the price can vary
considerably. Today, I would say it would take a minimum
of around $8000 and more nominally around $10000 for a complete
rotary installation in an RV – some folks could do it for less,
some for more.
But,
regardless of the technical merit (or not) in someone’s mind,
the crucial thing (in my opinion) is you need to address two
personal factors:
1.
What is your risk tolerance? It doesn’t really matter how
sexy some “exotic” engine installation may seem – if you are not
comfortable flying behind (or in front) of it, then it certainly
does not makes sense to go that route. After all,
this is supposed to have an element of fun and enjoyment to
it.
2.
What is your knowledge, experience and background (and you don’t
have to be an engineer) and do you feel comfortable with the
level of involvement needed.
So hope
you continue to contribute to expanding our knowledge and
understanding of the rotary in its application to power plant
for aircraft.
Best
Regards
Ed
From: Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Gary
Casey
Sent:
Saturday, April 11, 2009 8:36 AM
To: Rotary motors in
aircraft
Subject: [FlyRotary] Re:
Rotary Engines
Just to add a few more comments and
answers to the several excellent comments
posted:
How many parts does it take to make a
rotary rotate? Well, "parts aren't parts" in this case.
Mark was right in that there are maybe 4 "major"
components, but you have to define major. A piston engine
certainly has far more major parts. Is a valve a "major"
part? I think so. Is a rotor corner button a major
part? Not sure, but probably not. Is each planet
gear in the PSRU a major part? I say yes, and the PSRU is
an integral part of the rotary engine. As someone
correctly pointed out, it's not how many parts, but the
reliability of the total system that counts. Just looking
at the history of the rotary (which, from the implication of
another post) it's not that good, but I don't think it has
anything to do with reliability of the concept. It's more
to do with the experimental nature of the builds and
installations. My original point, perhaps not well
expressed is that to say there are just 4 parts is an
oversimplification. But let's face it, to put in an engine
that has had many thousands of identical predecessors is less
"experimental" than one that hasn't..
Are we ES drivers more conservative?
Probably so, since the ES is probably one of the
experimentals most similar to production aircraft, and not just
because the Columbia (can't force myself to say Cezzna :-) was a
derivative. Therefore, it tends to attract conservative
builders and owners. Not surprising then that almost all
ES's have traditional powerplants, with the most excellent
exception of Mark. While there may be more, I know of only
two off-airport landings caused by engine failures in the ES in
almost 20 years of experience. One was caused by fuel
starvation right after takeoff (fatal) and one was caused by a
PSRU failure in an auto engine conversion. So our
old-fashioned conservative nature has served us pretty
well.
Yes, I was assuming that the rotary had
electronic fuel injection and ignition, but that by itself
doesn't change the inherent fuel efficiency of the engine.
Direct injection does have a potential to improve BSFC
because the fuel charge can be stratified. It will
probably decrease available power, though. I think the
best rotary will be 5% less efficient than the "best" piston
engine(same refinements added to each). But I stated that
as a simple disadvantage - as Mark pointed out, it isn't that
simple. The rotary already comes configured to run on auto
gas. The piston engine can also be so configured, but the
compression ratio reduction would reduce its BSFC and maybe
durability advantage. The total operating cost is
certainly significantly less if auto gas can always be used to
refuel. I assumed in my assessment that it will only be
available 50% of the time. The real disadvantage, which I
failed to state, is that the extra fuel required for a given
mission might be 5 or 10% higher and that negated the weight
advantage, if only for long-range
flights.
Is the engine less expensive? I
did a thorough analysis of a direct-drive recip auto engine
installation and my conclusion was that if the auto engine were
equivalent in reliability to the aircraft engine it would likely
cost just as much. Is the same true of the rotary?
I'm not sure, but you have to consider the total cost,
including engineering of all the parts in the system, not just
the core engine. I would love to do a rotary installation,
but I don't think I could justify it by cost
reduction.
It wasn't mentioned in the posts, but
some have claimed the rotary is "smoother" than a recip. I
at first resisted that notion. Sure, any rotary given
sufficient counterbalancing, is perfectly balanced. A
4-cylinder opposed recip is not - there is a significant
secondary couple. The 6-cylinder opposed engine is
perfectly balanced, but only for PRIMARY and SECONDARY forces
and couples - higher order forces have never really been
analyzed, although they would be very small. And then
consider the forces within the engine that have to be resisted
by that long, heavy, but flexible crankshaft. So it isn't
the mechanical balance that gives the rotary an advantage.
Let's take a look at the the torsional pulsations,
comparing the 3-rotor against the 6-cylinder: A 6-cylinder
engine has 3 power impulses per rotation, as does the 3-rotor,
so they are the same, right? Wrong. They both
incorporate 4 "stroke" cycles, meaning that there separate and
sequential intake, compression, power and exhaust events so that
is the same for both. The power event, which is the source
of the torque impulse, takes 1/2 of a crank rotation for
the recip. In the rotary the power event requires 1/4 of a
ROTOR rotation, but the rotor rotates at 1/3 crank rotation -
the result is that the power impulse lasts 3/4 of a CRANK
rotation, 50% longer than in a recip. Therefore, the
torsional excitation delivered to the propeller, PSRU and to the
airframe is significantly less than for a recip. And if
you analyze the actual forces imparted, they go down by the
square of the rpm. The torsional vibration amplitude goes
down by a factor of 4 just because the rpm of the rotary turns
about twice as fast. If you've skipped to the bottom of
the paragraph, as you probably should have :-), yes the rotary
is "smoother" - a LOT smoother.. (my apologies to rotary
purists, for simplicity I used the word "crankshaft" for both
engines)
But just because you can burn auto gas
should you? The biggest problems with auto gas in recip
aircraft have nothing to do with the engine, but with the high
vapor pressure of the fuel - it is more prone to vapor lock.
The fuel systems of certified aircraft are not
particularly well designed with regard to vapor lock.
"Fortunately", rotary engines typically have no mechanical
fuel pump and are forced to rely on electric pumps.
Fortunately because the pumps can be located at the very
bottom of the aircraft and close to the fuel tanks, making vapor
lock much less likely. I would caution any builders to
consider vapor lock possibilities very seriously, much more so
if you intend to run auto gas. when I was going to do this
I planned to put one electric pump in the wing root of each
wing, feeding the engine directly(the check valve in the
non-running pump prevents back-feeding). Redundancy was by
a "crossfeed" line that could connect the tanks
together.
And thanks, Mark for - probably
incorrectly - referring to me as a "good engineer". I'll
have to put that in my resume!
(do you allow us outsiders in your
events? I'll park well away :-)
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