| |
|
As the heart of our aircraft, we
builders spend much time considering our engine choice. Once that choice
is made, then we have maintenance and operation to consider. This page
chronicles my engine choice and several operation and maintenance topics.
(click on a pic to see a larger
version)
|
The
Engine |
This is my O-360
A1A which was custom built by Bart Lalonde at Aero Sport Power in Kamloops,
BC. Bart is developing a great reputation in the experimental aircraft
community. Just check around among RV builders, there's a lot of
happy builders with these engines. Van's Aircraft has an Aero Sport
Power engine in the RV-9A demo plane and more than one Van's
employees are using them. Each engine is specially
built to your specifications.
I ordered mine with Unison LASAR ignition, slightly higher compression (9.2-1) pistons,
a spin-on oil filter
mount, and a bit of chrome to dress it up. Bart indicates it should
produce 190-195 hp. He test runs every engine for an hour but
unfortunately doesn't have a dyno to document the exact power
output. He will paint it to your color specs at no extra charge and
uses PPG Concept acrylic urethane for a very durable finish. Here it
sits on
the skid waiting patiently for me to mount it. Technically this engine is
not a Lycoming as you can see from the data plate. It's also not
certificated which makes it suitable for use only in an experimental
category aircraft, which my plane will be. This saves money on
certification procedures.
 It sure
looks better here than sitting on the floor - my engine takes it's
rightful place on the front of the plane. Now the long
installation journey begins. I'm using the Vetterman exhaust system:
it fits perfectly and looks very well made. Installation took maybe
45 minutes. The bolt and washer configuration is confusing but the
diagram Van's provides in the manual explains it thoroughly.
|
|
|
Contact
info:
Bart Lalonde or Sue Gregor
Aero Sport Power
2965 Airport Drive
Kamloops, BC V2B 7WB
Canada
(250) 376-2955
aero@mail.ocis.net
|

|
|
|
Engine
thrustline |
Measuring or setting the
vertical thrustline of the engine is not called out anywhere in the
manual or plans. Rather, the engine mount has been designed to
position the engine exactly level with the fuselage in the vertical
plane, and is offset some to the right to compensate for p-factor.
This horizontal offset of course comes to bear on any discussion on
offsetting the vertical stabilizer, but that is another discussion.
Regarding the vertical thrustline, I did some research on this issue
based on an observation at a builder's group meeting at my house. If
you're building an RV-8 you might find the results
interesting... |
Message
posted to RV-List 6/18/00
Listers,
Although this question
pertains to my RV-8 I believe the principal would apply to all RVs,
so here goes. About six months ago at a local builder's group
meeting at my house Bill Benedict was showing another builder how
the top of the engine should be level with the main longerons. He
had someone raise the tail and shim it so as to level the fuse as
measured with a bubble level on the cockpit sides (longerons). He
then put the bubble level on the engine to demonstrate this. He
indicated you could measure it longitudinally on the tops of the
valve covers, tops of the head castings, or the pushrod tubes. Using
the bubble level on all three showed the same results.
Turns out my engine was
not exactly level with the longerons, but rather tilted up a bit. My
buddy's SmartLevel was not there at the time so I do not know the
precise difference in degrees. I've been thinking about this in the
months since wondering whether to worry about it or not. The prop
(constant speed) was not mounted at the time and there was some
speculation that that weight would bring it down. I am now about to
mount my cowl and will need to either address it or not. After doing
some preliminary cutting last night on the cowl top half it does
appear that the rear of the spinner is not parallel with the face of
the cowl, but of course this could be a problem with the cowl (Sam
James) as well.
No where in the manual
or the plans is there any mention of checking that the engine, and
thus horizontal thrust line, is level. I could make a small
adjustment here by moving some washers in the upper engine mount
thus tilting the engine down slightly, but I have never heard any
mention on the list of anyone doing this. I have no idea how much
that would change things. So here's the question: what does anyone
know about this, and should it be addressed (removing my baffling
etc. to get to the right hand nut!)?
Thanks to those who
know,
Randy Lervold RV-8, #80500
Follow-up message posted
to RV-List 6/20/00
If you remember the
question I posted regarding my engine thrust angle relative to the
main longeron level then you might be interested in what I learned
and did. To refresh your memory, Bill Benedict spotted the fact that
my engine was not level with my main longerons, which it in theory
is supposed to be. We couldn't quantify it at the time because we
only had a bubble level. Well, Monday night I borrowed my buddy's
SmartLevel (man what a useful device!) again (I used it for mounting
wings and empennage which I highly recommend) and measured
everything. With the fuselage completely leveled out, both laterally
and longitudinally, the engine had .5 degrees of positive thrust
angle (tilted up at the front), and this is with the prop and
spinner mounted. I used a straight edge pivoted at the engine mount
and the SmartLevel to determine what that was in vertical inches at
the back of the spinner... it was 1/4-9/32". Most people with
O-360s (parallel valve) and c/s props are reporting about 3/16"
sag after 50 hours or so, therefore I would still be left with a
small bit of positive thrust angle (maybe a tenth of a degree) once
it sagged. Hmmm.
I called Van's Monday
and talked to Tom Green. We agreed that I'd quantify things and call
him back today with the measurements referenced above. Tom referred
me to Ken Krueger in the engineering department. I had a great
conversation with Ken and learned many things. Did you know that the
RV-3/4/8 all are spec'd with 1/2 degree positive angle of incidence
on the main wing, while the RV-6/9s use one full degree? The
thinking is that the RV-6 would be more of a cross country aircraft
carrying more weight and flying at higher altitudes, therefore they
gave it the extra half degree to support the weight and keep the
tail from sagging at cruise. Remember also that in theory these
planes cruise most efficiently when the longerons truly are level in
flight, which according to Bill's informal research most RVs do not.
Because of this, and
after thinking about it all day, I decided to put a washer in
between the motor mount and the engine boss on the top mount to
eliminate the positive thrust angle. Ken was fairly neutral on the
issue and said that indeed it may add a bit of efficiency, but the
difference would be small. Well, if it is going to be addressed it
needs to be now before I mount my cowl, so tonight we jacked up the
engine and put the washers in. (note that the plans call for TWO
small washers under the nut, so just leave one off which compensates
for the added thickness of the large washer). After getting
everything perfectly level again the SmartLevel can't make up it's
mind between 0.0 and +0.1 degrees of thrust angle. Yahoo, now if I
end up getting 3/16" sag this should translate into about
negative .1-.2 degree thrust angle. This is undoubtedly splitting
very very small hairs, but this should optimize the thrust angle and
keep it from cruising tail low, especially with Bubba in the back
seat.
In the final analysis I
do not recommend that other builders worry about this. If you think
about it an O-320 with a wood prop will only sag 1/8-1/4" and
will end up with a small positive thrust angle. Yet those IO-360
with c/s prop installs will sag the most at maybe 1/4-9/32" and
end up at zero. They will all fly fine, but I at least feel better
knowing that my thrust angle is as close to zero as is possible,
undoubtedly a product of my compulsive nature. Also, this way if it
sags more than anticipated I can remove the washers fairly easily
later.
Just think, now when
I'm cruising along at 201 mph I can fool myself into thinking that
that extra mph came from inserting the washer!
;-)
Randy Lervold
RV-8 #80500 |
|
|
LASAR |
Did you know
that aircraft magnetos have fixed ignition timing, just like your
lawnmower? We all know that aircraft engines are very simple devices
so as to be light and reliable, but seriously, there must be a
better way. Turns out there is. Experimental aircraft builders have
their choice of three electronic ignition systems for their
aircraft: one that is certificated, and two that are not. Unison
Industries, now owned by GE, and who makes Slick magnetos, for
several years now has made LASAR. What is LASAR? Here's an over view
from their web site:
"LASAR®, which
stands for Limited Authority Spark Advance Regulator, is the first
microprocessor-based engine control system approved by the FAA for
General Aviation piston aircraft. LASAR® differs from the full
authority digital engine controls, often called FADECs, used on
turbine engine aircraft in that LASAR® has inherent mechanical
magneto backup systems that automatically assume control if
electrical power is interrupted or if the microprocessor detects a
system fault."
Being
familiar with the benefits of electronic ignition systems on cars it
seemed a shame not to take advantage of this technology on my plane.
Why LASAR? I liked the fact that it's certified, I didn't like the
idea of plugs firing at different times as would be the case when
using one of the two other alternatives (could have some negative
impact on combustion flame propagation), had I had heard from other
pilots that factory support
was excellent.
LASAR provides some
significant benefits:
- Easier starting
- Faster rate-of-climb
- Reduced fuel
consumption
- Increased engine
smoothness
The Unison web site has a
bunch of great information. Check these links for more detailed
info:
Factoids and tips on operation:
- According to the manual,
LASAR works with bus voltage down to 7 volts. A typical 12v bus goes to 9.7 during cranking,
so you could have a fairly seriously depleted battery and still
have LASAR work.
- You can hand prop an
engine with LASAR. In fact since it enhances starting it is
actually easier to hand prop since it automatically retards
timing and provides a hotter spark, though I don't recommend it.
My buddy personally hand propped my plane one time when I had a
starter problem so I know this is true.
- LASAR will raise CHTs 10 degrees and lower EGTs 20 degrees exactly
as predicted. This is because it is burning more of the fuel/air
charge in the cylinder thus generating more power. I have
verified this by turning the LASAR off and letting the temps
settle out for ten minutes. When you turn it off you can
definitely feel that extra smoothness go away.
- LASAR is available both
with a CHT sensor circuit and without. This circuit monitors CHT
and automatically begins retarding the timing as the temperature
goes over a fixed point, I believe it is 450 degrees. This circuit was required for FAA approval on several airframes.
Experimental aircraft builders do not need to have this circuit
unless they want it. Be advised that it requires a special dual
tailed CHT sensor that will be different from your other
sensors. So as to use exactly the same sensors in all cylinders
I opted to not use the CHT circuit, but you must specify which
way you want it when ordering it.
- The LASAR brain has an
RS232 output so you can read what it's doing on your laptop
computer. I haven't tried this yet but plan to.
Lastly, my experience with
Unison's tech support has been fabulous. Harry Fenton manages this
function and he is very knowledgeable about the product, fairly
responsive, and is experimental-aircraft-friendly.
If you're interested in finding
out more AvWeb did a two part article on a LASAR installation...
http://old-www.avweb.com/articles/lasar1/
http://old-www.avweb.com/articles/lasar2/ |
|
|
Spark
Plugs |
Story coming soon... |
|
|
|
Replacing
the Cylinders |
“What,
you’re installing new cylinders on a brand new engine?” was the
question asked by all who heard I was indeed tearing things apart for
a complete cylinder replacement. Some background: I took delivery of
my engine in April of ‘99. At that time I opted for first-run rebuilt
Lycoming cylinders. I did this to save some money and also figured
that I’d have them off at mid-TBO anyway. In the next couple of years
as I finished the plane I sort of regretted this decision and wished I
had paid the extra money for new cylinders. Oh well, I wouldn’t have
to worry about for a thousand hours or so anyway.
April of
this year brought the first start of the engine followed soon by the
first flight and everything that brings with it. During the critical
first few flight hours I did my best to follow proper engine break-in
procedure: try to hold high power settings and high manifold pressures
and watch CHTs and oil temps. That is easier said than done. I had
probably the normal array of new airplane bugs to deal with, as well
as trying to get familiar with the flight characteristics of a new
airplane, and gather test data as well. To those who haven’t flown
yet: there is an almost overwhelming number of things to try to
accomplish in your first few flight hours. So did I break the engine
in properly during this critical period?
As the
summer wore on and the flight hours accumulated I changed oil as Bart
recommended and tracked oil consumption carefully. Toward the end of
the summer I had accumulated 130 Hobbs hours and was still noting oil
consumption of a quart every six hours. So as to eliminate the
possibility of a miscalibrated dipstick, and of blowing excess oil off
the top, I ran it down to 4 quarts indicated, same consumption. Hmm.
Next step was to discuss this with Bart. I faxed him my Excel tracking
table, this is the e-mail response I received from him…
Hi Randy,
I reviewed the oil
consumption record you sent in. I don't think it is going to get any
better. I suggest that we prep up 4 more cylinder kits and we replace
the existing cylinders. If the engine is running good right now we
could wait till your good flying weather is over. Think about this and
let me know what works for you.
Regards,
Bart Lalonde
I then
phoned Bart to fess up that I may well have not followed the break-in
procedure perfectly with everything else I was trying to accomplish
during those early flight hours. Didn’t matter, Bart was quite willing
to swap cylinders out regardless. Wow, now that’s support!
Since we
were swapping cylinders on warranty I asked Bart if I could upgrade
and just pay the difference, “sure, no problem”. After some
consultation I decided on brand new Superior sand cast cylinder
assemblies, which he promptly shipped after checking port flow and the
piston balance as he does with all his engines. He included all
gaskets and an assortment of pushrods so I could set the valve lash
properly. Total cost was $300 per cylinder, the difference in price
originally, plus shipping. One note: if I had been willing to fly the
plane up there he would have done the cylinder swap for me. But due to
the weather, not wanting to get stuck in Kamloops, and wanting to
learn this procedure for myself and at my own pace, I opted to do it
myself.
I
checked the compression before removing the old jugs: 79/79/78/79, no
problem there. On removing the old pistons I did notice blowby
staining on two of the piston skirts while the other two were
completely unstained below the bottom ring. I inspected the cylinder
walls for glazing but couldn’t draw any conclusions since I’m not
that familiar with what abnormal glazing would look like in an
aircraft engine.
The
month of October was consumed with the cylinder replacement, and of
course I took the opportunity to make some other minor fwf changes
include a cabin heat system re-design. I followed the cylinder
replacement procedure in the
Lycoming Operators Manual, Section 5-7
thru 5-12, which I found to be clear and well written. Since I had
some oil seepage of the cylinder bases on the old jugs I made a point
of being very careful when re-installing the cylinder base gaskets. At
Bart’s instruction I put them in place and then eliminated any
twisting, and also packed them in Dow DC-4 to keep them in place and
let them slide into place without binding.
What
caused the high-oil consumption? Did I cause this by not running the
engine hard enough during the early hours? Bart took a look at them
after I sent them back and reported that he did find glazing
"consistent with low power operation, high temperatures, or some
combination of both". I can assure you that that won’t happen this
time around.
This
time around you can bet I paid special attention to the break-in
procedure. The engine was ground run for only eight minutes once the
cylinders were installed: three minutes without the cowl to check
operation and for leaks, then another five for taxi and run-up prior
to takeoff. It was then run at full throttle and at 1,000' msl (forced
by local weather) the entire duration of
the one hour first flight, of course while watching temps carefully.
This regimen was repeated until 10 hours, and even in the next 10 I
used higher cruise power settings than I otherwise would. If it’s
possible, the engine is now even smoother — probably psychological.
In terms
of engine break-in, the single best document I’ve found is Cessna
Pilots Association Tech Note #035. It matches Bart’s recommendations
very closely, but also provides good background on why they make the
recommendations they do. Here are two quotes from that Tech Note that
sum it up: “...CPA staff suggests
operating at maximum rated continuous power if it can be done without
over-temping, otherwise reducing power only to the extent necessary to
keep temps in the green.” And later, just to show how important
the first few hours are… “My belief
is that if the engine isn’t broken in at ten hours, it just isn’t
going to happen.”
Of course
much is written from various sources on the subject of proper engine
break-in and many experts have opinions. Following is a table that
recaps what seems to be the common ground in all of them and that is a
good general regimen:
Break-in
recap:
•75-100% power for first 10 hrs
•Change oil as follows:
0-10 hrs: 40 mineral
10-20 hrs: 40 mineral
20-60 hrs: 40W
60-100 hrs: 100W
100 hrs +: Exxon Elite 20W-50 or AeroShell 15W-50 |
As of this
writing I have over 50 hours on the new Superior cylinders having
changed oil per the above table. Oil consumption was 1 quart in 6
hours up through about 35 hours, then it all of a sudden went down to
a quart every 15 hours. Note that this is well after I had switched to
AD oil from the mineral oil. I'm hoping it stays right there and will
continue to monitor it closely.
Two recommendations emerge from
this whole situation:
-
Run your
engine at full power for the first 10 hours, with the first 2 being
the most critical.
-
If you're
buying an engine from a builder for your unflown plane, consider
paying them extra to take it through at least a five hour break-in
regimen on their test stand. This did not occur to me at the time or I
would have gladly paid them for this service. Note that this should
include several sessions where the engine is run and allowed to cool
to provide heat cycles.
|
|
|
|
|
|
|
|
|
|
top |