Paul,
I'm just starting the disassembly / inspection of my 20B
for the
purpose
of an aircraft conversion. The thing that seems to be
worrying
me the
most is the water pump. That thing is huge, or at least it
sticks up in
the air a mile over the top of the engine
block. And....the
pump is
cast iron in an aluminum housing....very heavy!! Is there
some way
to modify, or preferably another pump that will mount in its
place that
will solve these issues? This thing will NEVER go inside
the engine
cowl?
Thanks again!!
Don Mitchell
No problem. Not to worry.
I'll give you a step by step on how to cut it down with
pictures. I
did one for Bulent and his is working and cooling fine.
Later today.
Paul Lamar ...No rotor no motor.
Don,
If I can jump in here with a comment or two. Yes the 20B wp is
big and
heavy. I'm in the process of converting my 20B to accept
the much
lighter Renesis front cover and wp, saving 6# and get the better
CAS in
the process. There is one bolt that will have to be drilled &
tapped, but that's the only mod that I could see. If you don't
want to
change the entire front cover, you can cut the wp section from
the Renesis front cover and just use the wp section on the
20B. Since I
wanted the newer style crank mounted CAS, I will be using the
entire
Renesis cover. The coolant inlet/outlet on the Renesis is
better
suited for a/c purposes.
Mark S.
Lancair ES - N/A 20B
Not so fast guys. The 20B impeller is a much better design
than the RX8 impeller. The RX8 impeller is the same as the
third gen. I think Mazda re-designed it for low average power
street car use to cut the WP power and improve the BSFC
slightly. It seems to work on Tracy's RX8 2 rotor engine.
Before I did something like this I would install a CHT
sensor near the lower spark plug on the front rotor housing
(tractor 20B powered airplane). Cooling wise the front end
housing is the least well cooled. Particularly on the 20B.
Paul Lamar ...No rotor no motor.
Paul,
Yes, I did the CHT mod as shown in
ROTOR_HOUSING_THERMOCOUPLE.JPG when I
had my engine disassembled and installed a thermocouple in each
rotor
housing. So, now I can monitor the temps as you advise. Does
anyone
know the flow rate of the Renesis wp?
If I recall correctly, Tracy is running a Renesis wp on his
RV-8. Since
he hasn't flown (that I know of), we'll have to wait a little
longer to
find out how well it cools.
Mark Seitle.
(we got two Mark S's )
Great Mark. I know you have not flown yet but what kind of numbers
are you seeing so far?
Please fly with the stock pump. We need some base line CHT data.
I don't have any data yet on the flow rate of the RX8 water
pump. The second gen are 30 gallons a minute.
--
Paul Lamar ...No rotor no motor.
Paul,
Sorry, I didn't record the cht's. I'll note that during the next run.
As I recall, they were just slightly higher than the H2O temp. I
suspect that will change as I load the engine more. Lots of things to
watch during this phase. Sure could use Tracy's data logger.
I didn't plan on making the Renesis mod until later on. I'm just
gathering the parts for now. You have to lock in the design somewhere
or it will never fly. ;-)
Mark Seitle.
I have a couple of data acq device I will loan you if you have a
note book
computer. Each device records four thermocouples values directly on
the hard disk. Search Google for Omegabus D5321. These are
K thermocouples -150 to 1250C. RS232 so you will need
a $20 RS232 to USB adapter cable and a terminal program that
runs in the notebook computer. I have two of these so you
can record 8 channels. All three EGT's, water temp, oil temp
and three CHT's and what ever else you need.
http://www.omega.com/
---------------------------------------------------------------
The D5000 Four Channel Sensor to Computer Modules are a family of
complete solutions designed for data acquisition systems based on
personal computers and other processor-based equipment with standard
serial I/O ports. The modules convert four analog input signals to
engineering units and transmit in ASCII format to any host with
standard RS-485 or RS-232C ports. These modules can measure
temperature, voltage and current. The modules provide direct
connection to a wide variety of sensors and perform all signal
conditioning, scaling, linearization and conversion to engineering
units.
The modules contain no pots or switches to be set. Features such as
address, baud rate, parity, echo, etc. are selectable using simple
commands over the communications port?without requiring access to
the module. The selections are stored in nonvolatile EEPROM which
maintains data even after power is removed.
The key to the D5000 series is that the modules are easy to use. You
do not need engineering experience in complicated data acquisition
hardware. With the D5000 series modules, anyone familiar with a
personal computer can construct a data acquisition system. This
modular approach to data acquisition is very flexible, easy to use
and cost effective. The modules can be mixed and matched to fit your
application. They can be placed remote from the host and from each
other. You can string up to 30 modules on one set of wires by using
RS-485 with repeaters.
All modules are supplied with screw-terminal plug connectors and
captive mounting hardware. The connectors allow system expansion,
reconfiguration or repair without disturbing field wiring.
THEORY OF OPERATION
D5000 modules are complete four-channel data acquisition systems.
Each unit contains analog signal conditioning circuits optimized
for a specific input type. The amplified sensor signals are converted
to digital data with a microprocessor-controlled integrating A/D
converter. Offset and gain errors in the analog circuitry are
continuously monitored and corrected using microprocessor techniques.
The D5000 converts the digital signal data into engineering units
using look-up tables. The resultant data is stored in ASCII format
in a memory buffer. The modules continuously convert data at the
rate of 8 conversions per second and store the latest result in
the buffer.
The host computer may request data by sending simple ASCII commands
to the module.
DIGITAL FILTER
The D5000 options include a unique programmable single pole digital
filter. The filter is used to smooth analog data in noisy
environments. Separate time constants may be specified for small
and large signal changes. Typically, a large time constant is
specified for small signal changes to filter out noise and provide
stable output readings. A smaller time constant may be chosen for
large signal changes to provide fast response to such changes.
COMMUNICATIONS
The D5000 are designed to be easy to interface to all popular
computers and terminals. All communications to and from the
module are performed with printable ASCII The D5000 will instantly
respond by communicating the ASCII buffer data back to the host.
-----------------------------------------
I am so happy you installed those thermocouples Mark. The CHT
is the bottom line on a lot of things. It affects detonation and
spark plug life as well as the integrity of the rotor housing.
Not to mention we can finally get a real handle on how much
water flow is really necessary to cool the engine at sustained
high power.
Paul Lamar ...No rotor no motor.
Paul,
Besides me, you're the first person that I've run across that thought
that this mod was of any real benefit. What is the recommended way to
install the thermocouples? I used red RTV, mainly because I wanted to
be able to remove them if necessary.
What do those data acquisition units cost? I wouldn't mind having one
for first flight and beyond. I already have a laptop. As evidenced by
my previous message, my memory isn't what it used to be. Do I need
to send my EC-2 back to Tracy's for upgrading in order to do this?
I have a basic DATAQ Instruments (
http://www.dataq.com/194.htm),
model DI-194 data unit. Are you familiar with this? Would it work?
Mark S.
Red RTV is good to 500 F so that should be just about OK.
The Omegabus modules are $250 each and there is free Windows software
on the Omega web site for controlling them. I will be glad to
loan you a couple.
No the system is entirely separate from Tracy system and you
can record almost an unlimited amount of data on a hard disk.
Notebook computers are getting smaller and smaller and
hard disk drives are being replaced by solid state flash
memory for excellent shock and altitude resistance.
The problem with the DI-194 data unit is they are +/- 10 Volt
input. The Omega units have the amplifiers needed for direct
connection to thermal couples. Thermal couples put only milli volts
and need special connections. also you get all that free Windows
software that will read out and store in C directly.
CHT is the crux of the problem with any high continuous power
engine.
Paul Lamar ...No rotor no motor.
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.