Kevin Alderman,
If you prefer there is a mechanical way around the dwell time
requirements for smart
coils like the LS1 and RX8 coils. These coils have a built in power
transistor for switching the
coil on and off and only require a 5 volt pulse. 5V on (charge) 0V off
and fire.
No computer and no software.
Use a 4 ms 555 one shot trigger by the CAS mounted on a movable plate.
Something that can be made on a lathe. The 4 ms is a minimum
charge time
for the coils.
You can mark the lever for start, cruise and full power.
Just like the old Ford Mode T :)
Hall effect sensors are the hot tip for the relatively clean aircraft
environment.
No VR board required.
They are low cost and reliable.
Paul Lamar
This might be usful:
http://www.elektor.com/news/____crazy-summer-deal-elektor-s-____embedded-linux-board.2538177.____lynkx
<http://www.elektor.com/news/____crazy-summer-deal-elektor-s-____embedded-linux-board.2538177.____lynkx>
<
http://www.elektor.com/news/__crazy-summer-deal-elektor-s-__embedded-linux-board.2538177.__lynkx
<http://www.elektor.com/news/__crazy-summer-deal-elektor-s-__embedded-linux-board.2538177.__lynkx>>
<
http://www.elektor.com/news/__crazy-summer-deal-elektor-s-__embedded-linux-board.2538177.__lynkx
<http://www.elektor.com/news/__crazy-summer-deal-elektor-s-__embedded-linux-board.2538177.__lynkx>
<
http://www.elektor.com/news/crazy-summer-deal-elektor-s-embedded-linux-board.2538177.lynkx
<http://www.elektor.com/news/crazy-summer-deal-elektor-s-embedded-linux-board.2538177.lynkx>>>
Murry I. Rozansky
You can get a full blown PC mother for that much money
and it will run Linux and boot off one of 4 or 5 USB ports.
Better yet boot real time DOS and write the software in 3rd grade
QB :) All free.
Paul Lamar
1. I already have a board that works with the code, it was around
$100.00 Yes I think the arduino mega or due would work- the others wont.
The short answer to why is that the others- like the UnoR3, etc. do not
have enough analog inputs for the sensors. The mega has a better
processor and 16 analog inputs for ADC. The mega android also has a chip
specifically for output to an android OS- not just a display but control
as well.
2. I have an ARM board that operates faster than the arduino and it
boots in linux, but I decided against this approach for a simple reason-
this board uses an SD card as a boot medium, and it takes over a minute
to completely boot up. So, either leave the master on and discharge the
battery to keep the computer on, or wait a minute after the master is on
to start the plane.
3. An arduino that will operate the coil ignition would not be that
difficult- using both top CAS pickups, and the bottom. Read the top at
202 degrees btc, delay it based on RPM, and, charge it for 4ms, then
fire. In theory this could be run around a bit farther for high rpm lean
mixtures. Not sure at the moment how to incorporate the additional
advance automatically, unless it is tied to the manual leaning. Have to
think about that. I guess the timing could be advanced manually with a
pot, but then you would have to have a piezo sensor incorporated in to
make sure you didn't go too far. More thinking-
4. I like the board that I have with the x gate- the x gate allows the
normal repetitive functions to be independent of the main processor- and
leaves much of the processor power for calculations. I also have a
Renesas board that has standard CAN communication protocol that lets it
communicate with other boards- It has way more power than is needed
also. For now, I will use the xgate board for the EFI.
The efi code as written (and modified by me so far) needs quite a few
sensors- intake temp, ambient air temp, MAP and ambient pressure, water
and oil pressure and temp, fuel pressure, CAS and the lower 12 tooth
gear as well. Will also need to monitor TIT and EGT and battery voltage,
all used to control the engine and let you know if something is wrong.
It should be noted that the FreeEMS guys as a group do not use the hall
effect sensors, they prefer the stock CAS. The consensus is that the CAS
is more robust than the hall effect sensor. That being said, the program
has several alternatives for using toothed wheels, or an opto isolator
wheel. The system can use either.
The code is in C, and shouldnt be too difficult to adapt the code to
take the xgate portion and put it back into the main or at least a
header file so that it will run on the arduino. Its on the list of
things to do- just need more time.
Paul- I have a Garrett T04 turbo- talking to my mazda racing buddies in
Miami, 8 psi should get me over 300 hp, and 12 maybe 325+. I will be
setting my rev limiter for 8500, and really hoping I will have enough
power to need it :). If I can get 300hp at 15000 ft, I will be tickled
to death. If you remember, I want an almost automatic system- so
eventually the limiter will be down to 7500, cruise at 6000, etc. Push
it to max- 7500 for T/O, first detent 6000 cruise- then descent, flight
idle, ground idle, etc. With manual override as well, of course.
KA
As far as the computer is concerned I am not only looking for
engine controls but a hi rez cockpit display as well.
It is best to do the engine control and the cockpit display
with the same program on one computer. It is all the engine
parameters such as EGT's, fluid temps and intake manifold pressure
that you need on a cockpit display. That is the reason I like a
stock mini form factor PC mother board. They all have super VGA
built in.
Tremendous market demand is forcing an ever higher level of
integration with an ever lowering cost at ever higher speed. They
are manufactured in the millions.
IMHO the days of the high pin count single chip computer are numbered.
It is simple to get 16 channels of A to D with one 8 bit port.
With a 2.85:1 the prop tips run in to the mach 1 barrier
at 7500 RPM.
You can go to a much smaller diameter prop but the efficiency of the
prop will drop at least 10% and maybe more. That is a big drop
in thrust. Thrust is the bottom line.
More HP will just burn more gas without going any faster at 7500 RPM.
Best to up the boost at 6000 RPM cruise and use wider blades or
three blades.
Make sure you put a turbo tach on the turbo charger.
IMHO it's life will be numbered in less than several hours if you get
it much over 80,000 RPM. This because the strength of the
turbine blade material is vastly reduce by the high EGT's of the rotary.
Paul Lamar
I agree on the turbo- and to help with that I will likely mount it
behind the engine to give the exhaust time to cool a bit. I plan to use
a pipe within a pipe cooled with ram air (like the heater cuff on
certified planes) to cool the gas somewhat before it gets to the turbo.
This hot air will be dumped overboard. I recently worked on a Seneca 2
with IO360 turbo engines helping with an annual- its EGT at lean cruise
shows on the instruments as 1600, but we tried to keep it around 1500.
The turbos are small, like the T03 that is stock on the mazda. Boost is
controlled by the pilot. I think the system should be able to limit
boost to whatever we want it to be. If we want 8 psi over sea level, the
system reads both pressures and should be easy enough to calculate and
limit the boost via throttle reduction. I want the throttle to be more
of a power setting and let the system take care of the rest.
Disagree on the prop numbers. My viking with 300 hp used a McCauley 2
blade at 83 inches. I used 84 inches prop length for these numbers, but
the props I have looked at so far are around 80 to 82.
SOS at sea level- 1116.437 ft/ sec (depending on density, could use up
to 1125)
7500 rpm engine and 2.85 geara box = 2631.57 rpm/ 60 = 43.8595 * 2pi*
3.5ft = tip speed of 965.57 ft/ sec
8500 rpm engine = 2982.456 / 60 = 49.707 * 22.015 = 1094.3. ft/ sec
Both well below mach 1. My viking with the 83" prop had a max rpm of
2950. Could be set to 3000 for up to 5 mins, but when I put the new gov
on I set it at the 2950. The tips were close to mach 1, and you could
hear me take off 2 miles from the airport, but it worked and was factory
and certified. Not to mention climbed like a rocket.
I dont like the idea of a PC mobo for the ECU either for one simple but
important reason- it has to "boot up". I said before that I have a nice
dual core ARM board that would easily run not only the efi but the whole
plane- led PWM, interior climate, etc. with processing power to spare.
but it takes a full minute to boot up before it works. The single chip
computers dont do that. If they have a hiccup, they can be reset and
immediately start back where they left off. Your car computer doesnt
have to wait to boot up, and neither should an efi. Your PC mobo has to
read the bios, then read the program and boot up before it starts its
job. In cruise an issue with corrupt sensor data or other anomaly that
requires a reset might be OK, where a minute might not mean much, but
close to the ground that is an eternity.
I have an ex brother in law that works on processing equip at
manufacturing plants. Most of the units he works on are run by single
chip computers on specific boards for a machine. Lately, these are being
replaced by specific boards for the machine but the computer part is
being replaced with an ARM version of the arduino. If there is a problem
he can program the ecu for that machine and replace it in a couple of
minutes. IMHO these units are here to stay, will keep getting more
powerful and cheaper. Repairs that used to require a complete unit
replacement or had to be sent off to reprogram it for a different
product are now being done in house for pennies. If a machine needs to
run a different part, reprogram the computer part, retool it and turn it
on.
http://grtavionics.com/grtremote.html
<http://grtavionics.com/grtremote.html>
I am installing the GRT EFIS in my first wheeler- there is an app that
lets you flight plan on your tablet, and it will bluetooth to the system
when you get in the plane. It also lets you use a tablet to monitor
other things you dont want on the display while flying- like instead of
having the engine parameters taking up part of the screen you can show
them on the tablet and use the whole efis screen for the map. The new
technology is here, and it is readily available reasonably priced
through economy of scale.
Picture this- program your flight sitting in the ac of the pilots
lounge, jump in your plane, power up and now your efis knows where you
are going with no boot up, no programming in the hot sun on the ramp,
just get in and go. The PC mobo and VGA are old technology.
KA
My prop numbers are based on a 72 inch wood prop.
What was the RPM on McCauley 2 blade at 83 inches?
Metal props tend to run faster as the prop tips are
thinner than wood props.
I have a really nice ARM board with LCD and a bunch of I/O
not to mention a plug in GPS :)
http://www.mikroe.com/
Paul Lamar
-
My IO 520D had a max gov speed of 2950. There was a SB that allowed
3000, but I didn't want to go that high. We set the new gov at 2950 with
an optical tach. Most of my takeoffs were max rpm until off the ground,
and before the end of the runway I was pulling the power and prop back.
She would climb at 2k / min at 140 knots right off the end of the
runway. No need to work it that hard, so I usually pulled it back to
2700 and 1500 fpm climb at 140. Runway 10 at X51 is 3600 ft, and when I
would take off, flaps and gear up by mid field, ground effect til the
end of the runway, I would pass through 140 knots and up we went. She
blew 2 cylinders at 1500 TT on engine, 850 STOH. Most vikings came with
a 3 blade Hartzell, mine was one of the few with the 2 blade McCauley.
Takeoff performance was almost identical, but my cruise was the same
speed on 2 gals per hour less. I averaged 160 knots, 23 squared, on 12
gph. The three blade vikings burn 13.8, 23 squared, 160 knots. The
difference is attributed to the extra drag of the third blade.
Everything else was the same- engine, wings, etc. KA
Fine pitch on a CS makes a difference as well.
Paul Lamar
The Rotary Engine News Letter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
You Tube
http://tinyurl.com/beqqxas
Copyright 1998-2013 All world wide rights reserved.