Introduction to
Turbine Model Flying
Sid Gates
AAM Meeting
1/4/2011
Turbine Engine Components



Most current
production engines are
Single Shaft with an
annular combustor.
The Single Stage
Centrifugal Compressor
is driven by a Single
Axial Flow Turbine
Wheel.
The shaft is supported
by two lubricated, preloaded angular ceramic
ball bearings
Turbine Engine Disassembly


Compressor and turbine wheel installed on the
shaft
No bearings shown.
Turbine Combustor

Annular Combustor – The
combustion chamber is
made out of stainless.

The hole pattern is
designed to control the
size and shape of the
flame in the chamber.
Side View
Combustor with Injectors





Fuel feeds in through the small
tube shown on top and goes into
a fuel manifold that goes around
the back of the combustion
chamber.
Twelve stainless fuel injector
needles are silver soldered into
the fuel manifold.
The ends of the needles are
placed into the rear of the twelve
vaporizer tubes.
The vaporizer tubes are soldered
to the back of the combustion
chamber and run approx. ¾ of the
way to the front of the
combustion chamber.
Vaporizer tubes atomize the fuel
for sustaining “well-behaved”
flame
Side View
Turbine ECU



An Electronic Control Unit
(ECU) monitors exhaust gas
temperature, RPM, ambient
pressure and controls the fuel
pump voltage.
The miniature fuel pump in
turn controls turbine speed
(thrust) by varying its RPM
and the fuel flow rate.
The ECU acts as an electronic
speed control so that fuel
pump speed is proportional to
the transmitter throttle stick
position.
Turbine Compressor




The spinning compressor
pumps air into the case.
Air is compressed
(density increased) and
passed to combustor for
fuel/air mix.
The diffuser shown below
straightens the air flow
as it goes into the case.
The sleeve that houses
the shaft is shown
attached.
Turbine Engine Disassembly 6

The diffuser is shown on the front (left) of the
combustion chamber and the Nozzle Guide Vane
(NGV) on the back (right) of the chamber.
Turbine Engine
RAM 500 engine disassembled (~12 lb thrust)
Turbine Operation



Test stand with engine
and all components
necessary to run.
The engine can be run
from the data terminal
or the transmitter.
The start/run sequence
to be described is for
the RAM 500, others
vary slightly.
Start Up Sequence



The start up sequence can
be initiated by the Data
Terminal or the Transmitter.
First the electric starter
motor spins the engine up to
approximately 6,000 RPM
then cuts off.
The engine is allowed to
coast for a short time and
then the ECU pulses the
propane (gas) solenoid and
lights the glow plug.
Start Up Sequence (cont)




The propane lights and the
engine accelerates to approx.
15,000 RPM.
If the RPM and temperate are
rising the ECU starts pumping
fuel (Kero or Jet-A).
The Data Terminal will then
display “RAMPING”.
When the engine reaches
50,000 RPM the Terminal will
display “RUNNING” and you
have transmitter control of the
engine.
Model Suggestions



You have the best chance of
success if you start with a
trainer jet such as the
Boomerang Sprint ($795.00)
for the 12-22 lb thrust engine.
If you start with a larger
engine the Boomerang Elan
or XL are very good choices.
Slower landing speed and
lighter wing loading.
If you are only interested in a
military scale model I
recommend the Top Gun F15 or any F-15 available
(Yellow, Fei Bao, Avonds)
A slightly higher performance
choice and the lowest initial cost is
the Tornado package offered
by Modellbau USA
Tornado Sport Jet Comb Package Model is
a redesign of a model that re- quired a lot of
mods for turbine operation. Engine is a
proven design.
Choosing the Right Engine
1.
2.
3.
4.
Decide on your budget.
Decide what size models
and whether Sport or Scale.
Your model choice will
dictate the size of Engine.
Chose the brand of Engine.
Main Stream Brands:
Jet Cat
WREN
Jet Central
Newcomer:
Kingtech
Purchasing New vs Used:





There has been rapid
improvement in engine design
the past few years.
Faster acceleration, lighter
weight and better fuel
economy.
Make sure you know the
engine designs short comings if
buying an older used engine.
ASK/CONFIRM used engine
has not been in crash or if was
serviced afterwards
Web searches are a good
place to research an engine.
AMA Turbine Waiver Summary

Turbojets and Turbofan single engine models shall not exceed static thrust
of 45 lbs. & multi engine shall not exceed 50lbs combined

RC fixed wing aircraft: The maximum velocity will be 200 mph.

All radios must be equipped with fail safe and the ECU shall be configured
to shut down the engine within 2 seconds of fail safe activation.

An experienced turbine pilot is defined as a pilot who has completed 20 or
more turbine flights during the preceding 24 months and who has a current
turbine waiver issued by AMA. For confirmation purposes, the pilot is
required to keep a written log of all flights and will provide copies to AMA
upon request.

An AMA member may be permitted to fly a turbine powered model on the
slave transmitter of a buddy box as long as the master transmitter is
operated by an experienced turbine pilot. All turbine waiver applicants
should have accomplished at least 50 flights on a high performance model.

Fixed wing: Model should be capable of sustained speeds of 100 mph or
higher.
AMA Waiver Flight Demo

The purpose of the flight test for the turbine applicant to
demonstrate their skills, knowledge, and understanding of
how to safely operate and fly a turbine model aircraft.

Key Elements: The following elements are to be demonstrated
through action along with verbal discussion of the element where
appropriate.
1.
Demonstration of proper turbine ground operations
a.
b.
c.
d.
Discuss the need to keep the tailpipe area clear of people and
flammable items during start, shutdown, and all ground operations.
Explain the response plan for dealing with an aircraft fire similar to one
resulting from a hot start. Fire extinguisher to be present per AMA
safety regulations.
Explain the potential for a post crash fire and the response plan to deal
with the situation. Explanation to include local fire department contact
number and fire fighting equipment immediately available for the
modeler to respond to the fire.
Explain and demonstrate typical turbine startup and shutdown
procedures.
AMA Waiver Flight Demo (cont)
2. Flight Skills
a.
b.
c.
d.
e.
f.
Takeoff, to be held within 10 feet either direction of centerline, with
smooth, controlled corrections as necessary.
Horizontal Figure 8. Pilot to hold altitude to within +/- 50 feet during the
Figure 8. This demonstrates skills at both left and right hand patterns
and the ability to control the models flight path.
Perform two aerobatic maneuvers with combined looping and rolling
elements to be selected by the turbine applicant. Examples include
Cuban 8, Humpty Bump with ½ roll, or similar maneuvers. This
demonstrates the general flying skills of the modeler.
High Speed Circuit of the field performed at a safe high rate of speed.
This demonstrates the ability to control a model aircraft at speed.
Square Traffic Pattern including a missed approach go-around. This
maneuver to be in the opposite direction of the takeoff and landing if
conditions allow. This demonstrates the ability to control a model aircraft
in the landing approach mode.
Landing to a complete stop. Again, smooth, controlled corrections to the
aircraft’s path after touchdown are required. The landing must be
completed on the runway.
* At no time during the flight shall the aircraft pass behind the
designated safety line.