My
Garrett GTP30-67 Turbine Engine
I originally
wrote this for my other web site www.WeldingFaq.com
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This
turbine had low hours, but had been in storage and was
in very poor cosmetic condition when I got it. The wiring was a 'rats nest' with cut wires everywhere.
After
I detailed it, I was pleasantly surprised at how nice
it looked. Since this unit weighs 87 lbs, I needed a
cart that would allow me to easily roll the unit around.
I blocked the turbine in place and fabricated the support
structure.
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I
designed the cart for both running and display purposes.
I refurbished a fuel tank from an outboard motor for
my fuel supply. Rated at 65 HP these engines are very
popular with hobbyists.
The Power Take Off (originally
designed for a generator, currently unused) turns at
8000 rpm. Here you can see the individual
parts that make up the GTP30-67. Here is one installed
in a Suzuki
motorcycle. This turbine will run on almost any
fuel including; Gasoline, Diesel, Kerosene, JP-8, JP-4,
JP-5, JET A, or JET A1.
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In
this left side view you can see the intake (Arrow 1)
and the igniter (Arrow 2). The ignition system is a
single Bendix igniter. The radial air intake is between
the compressor and the reduction gearbox. A single-entry
impeller is mounted back-to-back with the turbine wheel
on the main shaft.
This
is a one-stage turbine with a one stage centrifugal
compressor that has one combustion chamber. It was originally
used as an Auxiliary Power Unit (APU) to supply 400
Hz power for aircraft servicing.
The square frame allows me to stack junk on top when
not in use and serves as a handgrip for easy moving
and loading.
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This
close-up of the left side shows the Exhaust Gas Temperature
(EGT) sensor (Arrow 3) that sends a signal to the EGT
indicator to read about 520F or 290C at 100% RPM (no
load).
I
researched the component functions and designed my own
wiring diagram. I did not have a 24 volt solenoid so
I used a 12 volt 'Ford' style starter solenoid for powering
the starter. All the wire connections are soldered to
ensure reliability.
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A
Pneumatic Exhaust Temperature Limiter (Arrow 4) sends
a feedback signal to the fuel control. The igniter plug
(Arrow 5) functions like a spark plug (except it is
only used during the start cycle- up to 30% RPM).
This motor has great oil pressure and reads about 44
PSI on the gauge (Arrow 6) when turning at 100% RPM.
The Oil Pressure sensor (Arrow 7) shuts off fuel in
event of oil pressure loss. Oil Consumption is approximately
0.15 Pints per hour.
The
Fuel Nozzle (Arrow 8) sprays fuel into the burner can.
The Electric Fuel Pump (Arrow 9) pumps fuel through
the Fuel Filter (Arrow 10) to the Fuel Control. Removing
power to the Fuel Shutoff Valve (Arrow 11) is the only
way to shutdown the turbine.
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The
Overspeed Sensor (Arrow 12) kills power to the Fuel
Shutoff Valve in event of overspeed. The lubrication
system provides 32-37 psi from an air cooled tank (built
into the gearcase). The gearcase is serviced with Mil-L-23699
oil here (Arrow 13). The Burner Can (Arrow 14) holds
a continuous flame while the engine is operating.
A
pair of trusty Les Schwab RV batteries (Arrow 15) provide
24 VDC power. Once started, the only power required
is to energize the Fuel Shutoff Value into the open
position. The EGT and RPM gauges are self powered and
do not require 24 VDC.
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The
Starter (Arrow 16) spins the turbine up to 'lightoff'
speed (approximately 30% RPM) and from there it spins
right on up to 100%. The integral Fuel Control governor
provides automatic starting, acceleration, load and
speed control. The power to weight ratio is 0.68 shp/lb.
The
Tach Generator (Arrow 17) sends a low voltage signal
the the RPM gauge. I grounded the batteries (Arrow 18)
on the side of the gearcase. I used an outboard Fuel
Disconnect Fitting (Arrow 19) so I could stow the fuel
tank in my fuel storage area while not in use. The Fuel
Control (Arrow 20) is an electro-pneumatic type that
carefully meters the correct amount of fuel to sustain
100% RPM during all load conditions.
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Another view of the Fuel Control (Arrow 20). All power is routed through the Master Run Switch (Arrow 21) and the Starter Switch (Arrow 22) provides power to the starter and igniter during the start cycle.
The
Exhaust Duct (Arrow 23) puts out high temperature exhaust
gasses and the Exhaust Pressure Sensor (Arrow 24) provides
a feedback signal the the fuel control.
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I
use an outboard quick-disconnect fuel fitting (Arrow
26) to plumb the fuel source.
I
designed a 'control panel' for the switches and indicators.
The RPM Gauge (Arrow 27) reads in percent of rated RPM.
The Exhaust Gas Temperature (EGT) indicator is self
contained and requires only a millivolt signal from
the EGT sensor. The entire unit is flawless (except
for a crack in the EGT glass). The white 'master run'
switch was faulty and as been replaced with a 'mil-spec'
toggle switch.
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Under the
heading of "don't try this at home" here's how to modify the governor so you'll have the ability
to throttle the RPM between idle and 100%. This is from a GTP 30-57 but is basically the same.
Thanks to Jerry Green for contributing this modification.
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The governor weights are seen in the upper
part. The cap is what requires modification. There is an rpm adjustment screw on the cap.
What we are doing is removing the screw adjustment and adding a plunger rod with a packing nut to seal it.
Then you have to put a lever on the final changes.
You
do have to do some serious measurements. Before making
any modifications, you need to run the engine at 100%,
then remove the governor cap and measure the location
of the cup that presses against the spring. This is
the position for 100%.
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Then,
you have to start the engine and start screwing the
adjustment to lower the governor setting down to 50%.
Then, remove the cap and measure the position again.
This will be your slower (idle) position.
Now all the screw adjuster parts are removed from the cap. A 5/16 fine thread hex head bolt should slip through
the cap adjustment. The 5/16 bolt has to be center drilled for a 1/8 rod, and the spring thrust
washer silver soldered to the rod. When this bolt is installed in the cap, the rod should be
capable of duplicating the same positions that you had with the original measurements.
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Then
make a lever for it and that should do it. A word of caution (not serious unless for aircraft
use) a quick down throttle will shut the fuel off completely and will kill the flame front. The
engine will start spraying fuel once the governor catches up, but with no flame front the engine
will continue to spool down, fogging a few mosquitoes as it goes.
You can also throttle down, but not governor controlled, two other ways.
One, you can release
pressure out of the pneumatic line and fool the engine into slowing down to around 65% or,
two, you can meter fuel out of the injector fuel line, starving the engine into slowing down.
I still like having the governor control.
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This
turbine has been sold and the new owner plans to install it
in a motorcycle. More info to follow.
You may also want to check out my other turbine. It's a General
Electric T58 producing over 1,250 HP.
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