Jets Munt Merlin M122NG User manual

VT98NG - Merlin M122NG
Instruction Manual
(Version 1.5/2021)
Torrent d’en Puig, 31.08358, Arenys de Munt, BARCELONA,Spain
Tel/Fax: [phone]
www.jets-munt.com
E-mail: sales: [email protected]
service: [email protected]
© Copyright 2018, Jets Munt SL. All Rights Reserved
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Welcome!
Congratulations on the purchase of your new Jets Munt gas turbine engine. Jets Munt are
dedicated to the design and production of engines to the highest standards of quality and
reliability to bring you the customer the very latest next generation engine designs. The
MERLIN “XBL” and ”TS” models are the result of an intensive effort of design and tests by the
Jets-Munt staff. During the development period we made extensive use of the latest
Computational Flow Dynamics programs allowing us to optimize the engine performance
characteristics, and use the latest technology in electronics.
PLEASE READ!
The Jets Munt SL responsibility is limited exclusively to the repair of the engine and
accessories which are outlined in the conditions of warranty. Before unpacking the engine,
please read the manual, and agree to the conditions of warranty.
Customer satisfaction is important to Jets Munt SL. Technical support is available trough your
local dealer and trough email.
Jets Munt S.L
Torrent d’en Puig 31
08358 Arenys de Munt
Barcelona. Spain
Web site: www.jets-munt.com
E-mail: [e-mail]
Fax: [phone]
Legal and Disclaimer
The engine design and the contents of this manual are copyright by Jets Munt SL, Arenys de
Munt, Barcelona, Spain. All rights reserved. This manual, the pictures and data are property of
Jets-Munt and cannot be used or reproduced in any way without written permission from Jets
Munt SL.
Disclaimer
The MERLIN SERIES engines are a sophisticated piece of machinery. Care should be taken at all
times when using the engine. It should only be operated by those with the appropriate skills
and knowledge to do so. This engine is not a toy. Incorrect operation or misuse can cause
damage to property and bodily harm operators, spectators and animals. Jets Munt SL accepts
no liability for any kind of damage which may occur. Jets Munt SL assumes no responsibility for
any errors contained in this document and is not liable for any damages resulting from such
errors.
It is forbidden the use of this engine outside Radio Control applications, especially those that
power vehicles that carry people.
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Warranty
The warranty period for the MERLIN engines is 2 years from the date of purchase, or 25
running hours, whichever comes first. Warranty is valid solely for the original first owner and is
non transferable upon resale. Warranty includes all supplied parts, and is limited to
manufacturing and material defects only. Shipment costs forth and back, including packing and
customs fees are not covered by the warranty and will be always at owner expense.
Damage or defective operation covered under the warranty terms will be repaired and tested
at no cost the original owner (other than shipping expenses). Repairs not covered under the
terms of warranty will be carried out by Jets Munt SL or their appointed agents after
agreement of costs.
Before returning the engine or ancillary equipment for service of repair, please contact first to
your local dealer or Jets Munt central office to agree action and costs. Do not ship before
contacting JetsMunt!! Shipping anything from outside the EU without appropriate dicuments
will introduce delay and costs at customs.
Please do not disassemble this engine or any other item supplied (ecu, pump, etc). You will
breach your warranty agreement and you will find it is a precision assembly which you will be
unlikely to re-assemble without considerable difficulty and specialist equipment. Simply
slackening the spinner nut of the rotor will immediately lose the delicate balance condition,
without which the engine may not run without damage to its rotating assembly.
This warranty is void if any one or more of the following conditions applies. In such a case Jets
Munt will accept no responsibility for any damage or any other consequence caused by the
engine operation.
1. The product has been subject to any form of operation whilst containing incorrect
fuel, oil, or fuel/oil mix.
2. The product is crash damaged, pump is blocked due dirt ingestion, electronics or
pump are flooded by fuel, connection leads are cut or lost its isolation and short-circuit,
reverse polarity on battery, etc.
3. Unauthorized maintenance or modifications have been made to any part of the
product; including the unlocking of the ecu and changing the manufacturer settings or
any of the items supplied has been disassembled.
4. Parts have been damaged by ingestion of foreign objects (e.g. wires, sand, water
etc).
5. The engine has been operated incorrectly.
6. The product has been misused, neglected or inadequately maintained.
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7. Damage to the engine where blockages in the fuel system have occurred by
unfiltered or contaminated fuel.
Jets-Munt Representatives:
Check the current dealer list on our web page, www.jets-munt.com
Safety Notes
Please remember the engine is not a toy and has the potential to cause bodily harm to you and
others if misused. The MERLIN engine is a sophisticated piece of machinery and should be
treated with a high level of safety when it is in operation. It is your responsibility as owner, to
ensure safe, careful and considerate operation of your engine at all times, and in accordance
with the manufacturer's instructions. If you sell or give away this engine, please pass these
instructions to the new owner.
The following guidelines should be read carefully and adhered to.
1. Always keep a CO2 or similar fire extinguisher of at least 2Kg of CO2 contents close
when starting and operating the engine. Don’t use a powder extinguisher.
2. Always protect eyes and ears during the starting procedure.
3. Be aware of the extreme intake suction hazard, we advise the use of a suitable
commercial wire mesh Foreign Object Damage guard to protect the engine intake.
Ensure you have no loose items of clothing (ties, etc.) or equipment which can readily
be sucked into the engine intake, even from adjacent to the engine.
4. Always operate your engine in open air away from confined spaces as the engine
exhaust contains gases which can cause asphyxiation and nuisance smells.
5. Do not touch the engine whilst it is running. Turbines rotate at a very high rpm and
the engine casing and exhaust can reach very high temperatures. Ensure anything
affected by heat is kept well clear of the engine and exhaust during operation.
6. Never use the engine near to sources of flammable gases, liquids or materials.
7. Keep unauthorized persons, spectators, children and animals well away from the
starting area (at least 30ft or 10 meters away).
8. Always handle turbine fuel and oil with care as they are highly flammable. Store
them in appropriate labeled containers. Never dispose inappropriately. We recommend
the use of suitable disposable protective gloves for the mixing of turbine oil/fuel.
Turbine oil can be are hazardous to health and must not be allowed to come into
contact with skin, mouth, eyes or through ingestion, accidental or otherwise. Take care
when decanting and ensure any spillage is wiped away immediately and clean any
affected area with warm soapy water. Wash hands and any affected part immediately
after any contact.
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9. Continual failed kerosene starting or excessive priming of the fuel system can cause
excess fuel to build up in the engine chamber which can cause flaming on eventual
ignition. If fuel excess is suspected the only way to drain the engine is to tip the engine
forward and allow the fuel to exit through the fod screen and mop up with a rag. It is
no use tipping the engine with Merlin Instruction manual V1.4 Pag: 5 the exhaust
downwards as excess fuel will not be released due to the ngv being mounted forward
of the engine rear.
VT98NG
M122NG
Dimensions:
Diameter: 90mm (3.5”)
Diameter: 90mm (3.5”)
Weight:
968g (engine).
1.128g (total)
978g (engine).
1138gr (total)
Nominal
thrust @ 15C
and sea
level:
98N
12,2kg
Max.RPM:
151.000
152.000
Idle RPM:
41.000
40.000
Idle thrust:
4N
4N
EGT @ max
rpm
650-700ºC
650-700ºC
Fuel
consumption
272g/min
340g/min
Minimum
exhaust pipe
diameter:
70mm
75mm
Battery:
Reccomended 2s Lipo/>2200mAh
25C
Reccomended 2s Lipo/>2200mAh 25C
Glow plug
voltage typ.
7.0V
7.0V
Pump RPM
at Ignition
typ:
100 rpm
100 rpm
Minimum
ecu soft
version:
7.47
7.47
Restart:
Yes
Yes
Fuel/ oil:
Kerosene/diesel + 4% Oil See page 17 for oil types and percentages
Engine Description
The engine is a turbojet of a single shaft design specifically designed to power RC aircraft. The
engine starts automatically thanks to an installed electric starter situated in the front. The
starting sequence is controlled by an electronic unit that initiates the starting sequence and
controls the parameters of the engine within the design limits.
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The engine uses a system of direct liquid preheating, ignited by a long life ceramic glow plug
situated inside the engine. After the initial preheat the liquid fuel is gradually introduced. The
fuel should contain a small percentage of oil and uses part of this fuel to lubricate its two
ceramic high speed bearings.
The fuel for the engine is provided from an external fuel tank through a small electrical pump
that uses a three phase brushless motor. The engine speed between idle and maximum is
controlled by varying the speed of the fuel pump through an electronic controller called an ECU
(electronic control unit), that is connected to the engine trough a 3 wire digital data bus.
Installation Notes
1. The engine should be mounted using the strap mount supplied or an approved equivalent.
2. The connection cables from the engine to the ecu should be carefully routed away from the
engine intake so there is no possibility of accidental ingestion of the wire. Avoid placing the
cables close to the internal magnetic RPM sensor wich is located under the black cover at
approximately 2 o’clock when looking the engine from front with the electric connector at 12
o’clock. Cables too close can cause erratic RPM reading during startup.
3. Fuel pipe should be routed similarly clear of the intake.
4. The centre of the fuel tank should be mounted as near to the centre of gravity (CofG) of the
model as possible. This will minimize the CofG shift as the fuel is used during flight.
5. Any air ducting to the inlet of the engine must have sufficient diameter of at least twice of
the engine intake diameter.
6. If an extended exhaust duct is required, it should be of sufficient diameter and strength for
optimum engine performance. Leave a gap of 25mm between end of the engine exhaust to
exhaust tube (excluding bell mouth length)
7. Extreme care should be exercised to ensure that no foreign object, loose parts of the model
or debris are allowed to enter the compartment where the engine is installed.We recommend
testing the engine on a test stand prior airframe installation. You should have a clear idea of
how to arrange the components needed to run the engine inside the model. The main issue is
the fuel tank, you will need to arrange the CofG in the centre of the tank and adjust the
receiver and ECU batteries to achieve the correct location.
Electronic Control Unit (ECU)
The ECU is custom designed for the MERLIN engines and must not be changed for any other, as
this may result in improper control of the engine. Your engine has been set up and run with this
ECU at the factory and the settings should be left as default. The ECU plugs into your receiver
throttle channel and is powered from the receiver rechargeable battery. The ECU is
pre-programmed and only requires simply setting to your radio. The ecu is HV tolerant, accept
voltages up to 10V in the throttle connection.
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ECU Data Terminal
The data terminal plugs into the ECU via the lead supplied. The display can be used for starting
and test running. This socket also doubles as digital connection to a computer. The display can
be installed permanently on board. This Smart Data terminal includes dedicated screens for
radio checking, last shutdown cause and other special turbine operations. The most innovative
and useful function is the internal recorder/playback function. The terminal continuously stores
all the data received from the ecu, keeping in its permanent memory all the data of last 66
minutes of engine run, without the need of the memory card. After the flight, the terminal can
be pulled out of the plane and, without connecting to the ecu, just using a 5-10V battery, the
data stored can be played back in real time, same presentation as if the engine was running.
Playback mode can be still, forward or reverse, speed x1, x 10 and x100 in both directions, so
that would be easy to investigate any issue at the field without the need of a computer or any
other type of reader.
All the data, including all engine parameters, can be saved later to a memory card, where it can
be read using a text editor, or our viewer software. Also this data can be sent to engine
manufacturer to be studied. A detailed description can be found in last page of the present
manual.
The function of the buttons is described later in the “ECU setup”
Engine installation:
Electrical connections. Connect the power lead
of the battery to the battery socket.
PLEASE: DOUBLE CHECK THE BATTERY
POLARITY BEFORE CONNECTING IT TO THE
ENGINE. A reverse polarity connection will
immediately damage the electronic
components on both the ecu and the engine.
See the table on page 5 for the recommended
Lipo battery 2s. Other battery voltages are not
supported. Battery should be connected directly, DO NOT use
switches (electronic or mechanical), electronic regulators, diodes,
voltage regulators, etc. Multiple battery operation using a “Y”
lead is possible, but at least one battery must be directly
connected to the ecu.
Connect the throttle channel from your receiver to the socket in
the ecu labeled “throttle” and the data terminal to the socket
“Terminal”. Maximum voltage at throttle input port is 10V.
Connect the 3 wire powerbus to the engine and to the ecu. This
lead can be extended. Although Data signal can be used with lead
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lengths up to 10 meters, the power looses on power wires (red and black) will increase with
length, so thicker cooper section must be used on long lengths. Up to 1 meter, 1mm2 section is
OK. If you make your own extension lead, DOUBLE CHECK THE POLARITY. You will damage the
electronics inside the engine if polarity is reversed.
Engine installation:
Fuel system Install the fuel system components as seen in the above picture.
Pump: Note that the fuel pump has an arrow engraved in the front face indicating the
direction of the fuel flow. There are 2 types of pumps. Model 1304 are used on the engines up
to 120N; model 1307 is used on engines from 120 to 250N.
Fuel filter The fuel filter must be installed close to the input port on the pump to prevent any
particle to enter in the pump and to damage it. Use a suitable length of the clear tubing
supplied and keep the tubing on the suction side as short as possible. Direction of flow inside
the filter is not important, but should be always the same after first use. Install the filter in
vertical position with the exit on top to not leave air trapped inside. Do not run the engine
without the fuel filter.
Do not place anything (fuel filter, flowmeter, etc.) on the fuel line between the pump and the
engine. Check that the fuel line has the bends at suitable radius to prevent to the hose to be
pinched.
Finally connect the fuel pump and the battery to the ecu as shown. The fuel pump is a delicate
element, dropping it on the floor can damage it, always handle with care. Never disassemble
the fuel pump; warranty from pump manufacturer will become void.
It is strongly recommended that, after a new installation or modification on the fuel system, to
disconnect the fuel hose from the engine, routing it to a appropriate container, and run the
pump few seconds using the “pump test function” on the ecu so that some fuel clean all the
possible dirt particles that could have entered in the system during installation.
ECU (Engine Control Unit) Set Up
The new ECU system of the XBL/TS series is of modular design. All parameters concerning the
engine operation and run timers are stored in the engine and transferred to the ecu during
power up, enabling the replacement of the ecu without any adjustment, or, replacement of the
engine without readjusting the ecu, even with a different engine model. Check the table on
page 5 to check the minimum software version compatible with your engine model.
Parameters related to the installation, like radio setup, are stored in the ecu.
The ecu system supplied (ecu and engine) has been already tested and programmed at factory
for your engine. The engine has already been set up and tested using the same ECU and pump
supplied so there is very little to adjust in order to get the engine running, only the alignment
to your transmitter is necessary.
Confirm you have connected the ECU input to the throttle channel of your receiver,
DISCONNECT the ecu battery, and connect the Data Terminal into the ECU. Remove all rates,
8

mixes and throttle travel settings in the transmitter. Before doing any adjustment on the ecu,
check that your transmitter is sending the correct signal by checking the reading of “Pulse” in
the data terminal. It should be between 900-1050uS at STOP position, between 1100 and
1300uS at IDLE position and between 1800 and 2200uS at Full Power position. Please note that
these readings on the ecu are measured directly from the signal received from your RC system,
so you should readjust your transmitter if the values read are outside that the ones suggested.
The setup assumes the use of a transmitter with manual trims. If you use a TX with digital
trims, is essential to use the switch in the TX programmed for the function "Throttle cut", or
“engine cut” which normally has the effect of producing the “trim-down” function. Using a
digital trim cause unstable idle, and delay in shutting off the engine in emergency. Check
your radio manual for this before you start. Avoid using the digital trim if possible.
Aligning transmitter with ecu
As the display does not photograph well we have reproduced
the display readings as a green box. Turn on the transmitter
and receiver. The opening screen should show as below:
Note there are four buttons on the display, two on the left and
two on the right hand side. The left buttons move to the
different screens and the right buttons are used to change the
values stored. Press the second, left button and scroll through
the menus until you find the one showing:
Press the (-) button and the display will show the “Radio”
parameters menus. First screen shows graphically the current
adjust on the radio. Press the (^) button to enter in the menus
to adjust the radio.
Press the (right hand button (+)) to confirm that you really
want to program the radio. The screen will change to:
On your transmitter, raise first the trim to full, and next
the throttle stick to full, in this order. Ensure stick is firmly
against the stop. Now holding the stick against the stop,
press the right button (+) to store the signal from your TX
into the ECU.
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The screen will now change to:
Move the trim to low (or switch the “engine cut” switch
to On) and throttle stick back to zero and again press the
right hand button (+).
The display will now change to:
Leaving the throttle stick in the minimum position, raise
the throttle trim to the full up position or switch “Engine
Cut” switch to off, and again press the “+” button to
store the Idle position into the ecu.
If you have done all steps correctly the blue LED in the
ecu will light up flashing 2 times in the ECU when the
“Idle” command is received, meaning that trim and
throttle stick are set to idle positions on the transmitter.
Lower your throttle trim and the LED will change to a
single flash sequence indicating correct reading of the
transmitter engine shut off signal by the ecu.
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On some Futaba transmitters, it has been found that the throttle channel the sense of
movement may require reversing (Servo reverse) and to repeat the transmitter alignment. The
correct adjustment of the throttle adjustment on the ecu can be verified in the second screen
of the data terminal, the percentage of the throttle position should read 0% at the position of
engine stop (trim and stick down), 100% with stick/trim full up
and between 10% and 30% at idle.
This now completes your radio setup and should only need
doing again if the radio settings are changed.
Failsafe:
Never fly with the failsafe set to “hold”. It is strongly recommended that you setup your radio
system with the correct failsafe settings. In some countries is mandatory that the engine stops
in 2 seconds in the case of a failure of the radio link.
To program correctly the failsafe on your radio:
1) Adjust the travel of the throttle channel from -100% (stop position) to +100% (full
power)
2) Adjust the ecu to your radio as described above.
3) Adjust the failsafe position of the throttle channel in your radio to a -125%.
If all is correctly adjusted, the ecu will stop the engine immediately when receive the STOP
signal (-100%), but if the signal received is Failsafe (-125%) the ecu will set Idle power during 2
seconds, and, if after these 2 seconds the Failsafe condition persist, will shutdown the engine.
Once you have the radio programmed, you can check it by setting the throttle to the different
positions, and then switching off the transmitter; in this case the “failsafe” reading should be
displayed.
There are many more parameters that can be modified in the ECU, but we have specifically
programmed your ecu with the optimum settings, further adjustment should not be required
and can only be carried out by Jets Munt SL or your authorized dealer.
Preparing the engine for running
A suitable platform/table/workbench is now required to clamp the test stand onto. Make sure
this can be easily transported outside and weight enough to ensure it cannot be blown over by
the thrust of the engine.
Select a clear area for running – keep clear of areas with loose leaves, sand or other debris that
could be picked up or drawn towards the intake. Ensure the fuel tank is position well clear of
the exhaust area and secured.
Important notes for kerostart engines. PLEASE READ
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The kerostart system used on this engine is a reliable and well tested system that produces very
smooth and trouble free starts.
However, extra care and attention must be paid when starting a kerostart engine.
The main difference between gas and kerosene is that in the case of a failed ignition, the gas
dissipates quickly on the air and don't keep inside the engine. Kerosene is liquid and, if
unburned, will pool inside the engine and stay there forever. The engine can hold a big quantity
of kerosene inside. This kerosene will be ignited on next successful start up and will be pushed
to the exhaust as soon as the airflow inside the engine is sufficient, then it will be ignited in the
exhaust, causing a hot start (in extreme cases a big fireball) that surely will not hurt the engine,
but can destroy the model.
To prevent this:
-During the start-up listen to the engine sound to check for positive sound of
ignition, check looking from the exhaust that the kero is burning, or check for an
increase in exhaust temperature in the data terminal. A small plume of white smoke
from the exhaust means that the fuel is not burning. The fuel is pooling inside the
engine. Abort immediately the start.
-Double check that the engine is not flooded. An extra security measure is to
place a manual valve between the last fuel tank and the pump intake line, to prevent
that during the process of filling the tanks or during storage, some fuel can arrive to the
engine.
-After a failed start, or whatever condition that could cause that fuel be
collected inside the engine (i.e. extra priming), ALWAYS empty the engine of fuel by
tilting the engine nose down. Fuel will exit trough intake. Do not tilt upwards; due at
the internal engine construction the fuel cannot exit trough exhaust.
Another big difference between gas start and liquid start is that the kerosene can keep burning
slowly during long time inside the engine. This situation usually happen during an aborted
start, the start-up sequence is aborted by the user or automatically before the engine arrive to
idle. This can cause that the kerosene inside the engine keep burning for long time, and could
destroy the engine or the model. IF A STARTUP SEQUENCE IS NOT COMPLETED, ALWAYS
CHECK FOR FLAME INSIDE THE ENGINE. If there is flame, then set full throttle for over 3
seconds to engage the starter and blow out the flame. USE SHORT BURSTS OF STARTER. Using
the starter for long time can destroy the starter motor. In the case that the start-up procedure
has been aborted due at starter failure, then it will be necessary to apply the CO2 fire
extinguisher. A white smoke plume from the engine is a good indication here; mean that there
is no fire inside.
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First engine runs
· Confirm your test stand is securely fixed to a bench or heavy table. Keep your
ear defenders within easy reach and a CO2 fire extinguisher handy. VERY
IMPORTANT ON KEROSTART ENGINES. Do not use a powder extinguisher, it
will damage the engine.
· Fill the fuel tank. Do not forget to filter the fuel, and to mix the oil.
· Confirm all batteries are freshly charged and connected up.
· Check there is a temperature reading on the data terminal.
· Ensure the running area is clear of onlookers – especially the prohibited zone
of a 10 metre radius 180° arc from engine centre around the rear
· Verify that the fuel tube is full of fuel and purged of all air, if not; carry out the
fuel prime sequence as described here.
Priming the fuel system:
Fuel line need purging of all air after initial installation. Take extra care when priming the lines,
ensure fuel is primed only up 5cm before to reach the engine; too much fuel inside engine will
cause excessive flaming during start sequence.
Priming is achieved by a special menu on the ecu. Set the trim to low and go to “Info” menus
and next to “Pump test”. Click on “on” /”off” to start/stop the pump manually. Please observe
fuel line to engine very carefully and push the off button to shutoff as soon as fuel reaches
close to the engine. Best too short than to flood the engine.
IMPORTANT: The prime procedure should be done only to fill the fuel tube and filter in the
case of a first installation or in case of disassembling of the tubes. Do not run Merlin
Instruction manual V1.4 Pag: 13 the prime function so that the engine becomes flooded by
fuel, as this will cause an uncontrolled fire at next startup.
Starting the engine
Set the throttle stick down and the trim up. “Idle” - Confirm that the LED in the ecu is blinking
in a sequence of 2 blinks and the screen shows "Ready" - !Ready to start!. In the case that the
exhaust temperature is over 100º, the ecu will power the starter to cool down the engine. Wait
until the cooling sequence finish.
Move the stick to full throttle and immediately back to idle again. The Ecu will begin the
startup sequence as described below:
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First the internal glow plug will be energized. After 3 seconds, the starter will be powered up to
have the rotor turning at slow speed (3000- 5000 RPM).
Once the rotor is at correct speed, the pump and solenoid valves will be energized. Few
seconds later the kerosene will ignite and the exhaust temperature will begin to increase. The
rpm and pump power will increase automatically. During this phase the data terminal will
display “IGNITION”.
When the ignition is detected, the data terminal reading will change to “SwitchOver”, during
this phase the fuel will be routed to main injectors and the speed of the rotor will be
progressively increased to about 10,000 -15.000 RPM, depending on engine model.
Once this phase is finished, the reading will be “FUEL RAMP”. In this phase the ignition system
is switched off. The fuel flow and starter power will be increased automatically to increase the
RPM up to idle RPM.
Before arriving to idle the Ecu will automatically disconnect power to the starter. When the
rotor speed reaches idle, the screen will change to “Run IDLE” and the engine speed is adjusted
to the IDLE RPM.
The engine is running!
Control of engine power/rpm is now handed back to the transmitter and controlled by the
position of the throttle stick. Increase/decrease the throttle slowly, verifying that the engine
accelerates/decelerates following the throttle command. Take special care around the engine
intake; keep your hands at a safe distance along with any other objects as they can be easily
ingested.
Engine shut down procedure:
To shut down the engine lower the trim and the stick. It is recommendable that before shutting
down the engine to restrain the model and then raise the throttle stick to approximately 25%,
allowing temperatures to stabilize for around 5 seconds before carrying out the shutdown
procedure. After the shutdown the ecu will keep the starting motor running to cool the engine
under 100ºc. A special feature on this ecu system is that the power of the receiver can be
switched off before the cooling procedure is complete. The ecu will shutdown itself when the
procedure is complete.
WHAT TO DO IN THE CASE OF AN EMERGENCY
During the start sequence the Ecu will be in charge of everything, controlling temperature and
RPM. The only thing the user can do is to abort the sequence by lowering the trim in the case
that something abnormal (excessive flames in the exhaust, etc).
14

If a problem is detected, first:
Move the trim to the low position to abort the sequence. If there is a fire in the engine and the
problem is because the starter has failed or the engine is seized (not turning), IMMEDIATELY
APPLY THE FIRE EXTINGUISHER through the intake side of the engine, never trough the
exhaust.
If there is a fire, but the rotor remains free to spin and the starter is OK, raise the trim and stick
to the full power position for 3 seconds, this will connect the starter manually to ventilate the
engine and extinguish the fire. The throttle channel acts as a starter switch.
Adjusting the engine maximum power
The engine comes from factory adjusted for its maximum thrust. But it is possible to reduce the
maximum power if necessary. To do so, go to RUN menus and scroll the menus up to “Max
RPM”. Using the + and – buttons, you can change the rotor speed at full throttle. On engines
using ecus of version 7,42 or higher, on this screen is displayed, besides the full power RPM,
the equivalent thrust in Newton and in Lb. Please note that these figures are calculated
supposing an ambient temperature of 15ºC at sea level. Hotter ambient/higher altitude will
reduce the power output.
Autorestart function
All JetsMunt engines in production include the AUTORESTART function. This function can
quickly restart an engine automatically in Flight, but it should be understood that such a system
may cause damage to people and property. By default this function is disabled in the ecu, the
user should expressly enable it. By enabling this function, the user agrees that he/she has
understood the working principles and understands its limitations.
Restart options and how to enable them
Within the “Radio” menu, a new choice has been added to define the restart operation. The
ecu offers 3 choices:
·Standard operation: After the shutdown the ecu should be reset (power cycled) to enable
another startup cycle. Engines are supplied in this mode from factory.
·Manual Start: user can normally shutdown the ecu trough the transmitter (by lowering the
stick and trim). The ecu will execute the normal shutdown and post run cooling. Once the
cooling is finished (temperature below 100ºC), the ecu will return to power-up state, allowing
the engine to be restarted through the normal procedure (Trim-up, cycle stick). The time to
shut down and later start is exactly the same as standard operation. This mode is useful for
gliders, where the engine is used to climb to height, shutdown, soaring, restart, climb, etc. This
15

mode does not pose any safety hazard besides the fact that the engine can be started
inadvertently if the start procedure is executed in the transmitter after the flight.
·Autorestart: In particular case of a fuel bubble that momentarily stops the combustion, the
ecu will detect this condition by monitoring the rpm, temperature and pump power, and then
the ecu triggers the auto restart sequence. This sequence is done with the engine hot, so the
power is restored quickly. This restarting function can help save the plane in few limited
circumstances, but it can also greatly increase the risk of fire, so before to enable this function,
please read and understand the following:
What does the auto-restart function does:
It automatically tries to restart the engine quickly and restore the power setting that is being
asked by the transmitter.
To trigger this function, the ecu checks:
-The radio signal is valid, no failsafe condition.
-The readings of the RPM are consistent with a flameout condition (the speed of the RPM
coasting down is between preset limits).
-The readings of the EGT are consistent with a flameout condition.
-The battery voltage is good.
-No other faults detected.
Once the ecu is satisfied that the shutdown/flameout was most likely caused by an interruption
of combustion, usually caused by an air bubble, the ecu triggers the quick restart function,
where the ignitor is energized to full voltage and the pump is started at a power dependent of
the current engine status (RPM and EGT). Once the ecu detects that the combustion has
reassumed, the starter power is set to full power to reach the idle rpm as quickly as possible,
and the pump power is increased accordingly to the real RPM increase, allowing for delays
caused by bubbles arriving to the engine. If after 10 seconds of restart the ecu doesn’t detect a
stable combustion, the procedure is aborted and the normal cooldown initiated.
What the autorestart function will not do:
-It will not restart the engine if the shutdown was caused by any fault other than a typical
flame out caused by air in the fuel system.
-It will not monitor and confirm flight conditions are optimum for a restart. Leaving the restart
to progress is the pilot responsibility and decision, depending on each particular case.
When should Re-Start function be enabled?
Restart takes an average time of 15s to establish restored level of pre-shutdown power. It is
highly recommended that Re-Start only be used on airframes capable of sustaining enough
flight for the re-start to be complete. Some aircraft examples include: lightly loaded planes,
gliders, or multiengine planes.
It is highly advised that a shutdown simulation be done before selecting Re-Start option in the
ECU Menu. Do it during a normal flight at a high altitude, then throttle down to idle then begin
a 15sec count down. From this try to gauge if the aircraft can maintain controlled flight during
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this time at idle setting. If your plane cannot maintain flight for a minimum of 15sec without
engine power, do not enable the restart function.
-I’m flying my plane and the engine has shutdown with restart enabled, what should I do:
1) Think that the chances of that the engine restart are slim. You don’t know why it has shut
down, so likely it will not restart, DO NOT RELY on it.
2) Fly your plane. Leave the throttle at mid setting and fly your plane keeping airspeed in aft for
a dead stick landing.
3) In case you see the plane begins to stall or an uncontrolled landing is most likely,
IMMEDIATELY set the trim and stick to STOP position to abort the restart function. A crash with
the engine running normally ends with a fireball; a crash with the engine off is not likely to
catch fire. Do not use the “digital trims” to shut down the engine, use a dedicated switch to be
operated quickly.
4) If the engine restart is initiated while on approach, evaluate if the speed/position of the
plane is still good for a safe landing, if so, land immediately, you don’t know why the engine
stopped and may stop again during a “go around” but this time the aircraft may not be in an as
favorable position. If the position/speed of the plane is not convenient, use the engine power
to go around and plan for a normal landing, BUT land as soon as possible.
5) Once the plane is on the ground, even in normal landing or crash landing, set the
transmitter in the STOP position. The engine could restart and go to full power on its own; the
ecu does not know when the plane is on the ground.
-Can I use the restart function many times? NO!
Restart function is an emergency procedure and places a high stress on the engine ancillary
components. The starter and ignitor are fed with extra power that is not used in normal
startups, this places considerable more wear on them, also the engine is subjected to abrupt
temperature changes that could shorten its life.
Restart function is not the replacement of a poor fuel system. It can save a plane in particular
circumstances, but it can do much more harm than good. A belly landing or landing gear
damage due to a flameout induced heavy landing is more favorable than a similar landing
arrival with the engine in start phase that can possibly cause a fire and result in total
destruction of the model and or property. Please Think twice before enabling the auto restart
feature.
Disclaimer:
There are no circumstances Jets Munt P/L or any of its Service Agents and employees will
accept or be held responsible for any losses or damages the Auto Restart feature causes should
the owner operator choose to enable this function.
Throttle curves
By default the ecu control the RPM in linear way, i.e., at half stick position the engine turn at
half of the rotor RPM range. Jet engines develop the thrust in exponential mode, thus half RPM
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means approximately ¼ of thrust. On small engines with a high idle to full power rpm ratio, or
in a high drag/low power planes, often only the last 1/3 of the throttle stick produce significant
thrust, with the low half stick travel being not used. Although that with current digital TX the
pilot can modify the throttle curve to suit his needs, three throttle curves have been added to
simplify the setup for most of the installations. These curves are selected under the RADIO
menus:
FULL EXPO: Mean linear RPM, it is the default setting and the mode used for all previous
software versions. Thrust develops exponentially, and it is the recommended curve for big
engines or/and high thrust/weight ratio planes, as it ease the control in low power used during
taxi.
LINEAR: Mean that the thrust develop linearly with the throttle setting. Could cause difficult
taxi, as it would be difficult to fine adjust the power at low settings.
HALF EXPO: An intermediate setting between the other two modes.
Throttle curves can be changed while the engine running, so you can leave the throttle at a
given position and switch between the curves to see the difference.
Acceleration and deceleration settings
Under the “RUN” menus is possible to change the acceleration and deceleration times. The
engine is supplied and tested from factory ready to use and usually these settings should be
correct for normal use. However the user can modify these default settings to allow the engine
to run optimally in different conditions.
Leave the acceleration and deceleration in “fast” mode when using the engine with kerosene
and at ambient temperatures below 25ºC and elevation below 500m. If diesel fuel is used, or
ambient temperature is over 25ºC or altitude is over 500m, then the engine could experiment
difficulties in accelerating. In these cases, try to set the acceleration to “normal”, “slow” or
“very slow” to find a setting where the engine operate normally. It is much better to have an
engine than respond slower to throttle changes than one that just stop when asked to
accelerate faster than possible in difficult ambient conditions!
Exhaust tubes
The size and placement of the exhaust tube is not an exact science. The optimum tube
diameter and the gap between the engine exhaust and the tube intake is largely dependent of
the airframe. An slow airframe with big intakes will benefit of larger exhaust diameter and
larger gap, to get the maximum static thrust possible, while a fast airframe, with small intakes,
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bypass installation, will benefit of smaller exhaust diameter and smaller gap, to get the
maximum efflux speed.
As a general guideline, use an exhaust tube of a diameter equal or larger than the specified in
page 5, with a gap between the engine exhaust and beginning of exhaust tube (excluding the
bell mouth) of 25mm. later you can experiment moving the engine 5mm forward or aft to see if
performance is better. Too larger gap will cause hot gases to recirculate to the engine intake,
decreasing performance and worsening the acceleration. Too short gap will cause extra pipe
noise and depression inside the pipe, in extreme cases the exhaust tube can collapse due the
low pressure inside (venture effect).
Use in gliders, 3D planes and high Gs maneuvers
If you plan to use your engine in a glider, please consider to de-rate your engine. The typical
use that is running at full power continuously for the entire flight in airframes that easily
weight 4 times the engine thrust is very hard for the engine, as the internal elements like
combustion chamber are subjected to maximum temperature and stress all the time, reducing
the time between overhauls.
We would recommend using the engine at 80% of its maximum power in these conditions, or
using the 100% for takeoff, but later reducing to 80% during continuous climb. We don’t
recommend using our engines in 3D planes doing fast aerobatics and high Gs maneuvers. The
gyroscopic forces that an turbine rotor turning at +100.000RPM apply to the bearings doing a
loop in less than 1s are extremely high and can destroy the bearings or cause the compressor
or turbine wheels to rub to the engine case. These damages are not covered by the warranty.
List of ECU message codes
Here is a list of possible messages shown on the data terminal screen and their meaning.
TrimLow: Indicates that the signal received from the transmitter corresponds to the lowered
trim, that is to say, engine OFF.
Ready: Indicates that the engine is ready for starting, and that the transmitter signal
corresponds to IDLE, (LED lit twice)
StickLo!: This indicates that the throttle stick is in a position above IDLE, the engine will not
start with the stick in this position.
Glow Test: Verification of glow plug StartOn: Test of the starter and rpm sensor Ignition:
Ignition phase.
SwitchOver: Phase of heating of the combustion chamber after detecting the ignition.
FuelRamp: Phase of acceleration until idle speed.
Run Idle: Engine working correctly, pilot have full control of engine power, command received
from transmitter is IDLE.
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Running: Engine working correctly, pilot have full control of engine power, command received
is an intermediate setting between Idle and Full Power.
Run-Max: Engine working correctly, pilot have full control of engine power, command received
is Full Power
Stop: Engine off.
Cooling: Starter is operating to cool the engine.
GlowBad: Defective or disconnected glow plug.
StartBad: Defective starter, insufficient RPM reached during start, RPM sensor damaged, too
thick oil used on previous run, no cooling sequence done in previous run.
Low RPM: Engine had been shutdown because the speed has fallen below the minimum.
Usually lack of fuel (bubble)
HighTemp: Excessive temperature Battery!: battery voltage out of limits.
No Engine data: Data bus disconnected from the engine.
Pump Overload: There is a restriction in the fuel pathe from the pump to the engine, or in the
engine itself.
Diagnoses
During engine operation the Ecu measures and stores all the engine operating parameters
recorded during the last the 51 minutes of operation. These measures can be downloaded later
to a PC to study the behavior of the engine in flight and to diagnose any possible problems.
Also, after each cycle of operation, the Ecu stores the last cause of shut down and the values of
RPM, temperature and pump power. In order to access these measures, it is necessary to shut
down and power-up the Ecu. Set the trim down (trimLow) and push the left button on the
display. The Ecu will show the cause of last shutdown and the parameters value at the moment
of shut down. These are as follows:
Diagnosis messages:
●UserOff: The engine has been shut down because it has received the shut down
command from the transmitter.
●FailSafe: The engine has been shut down because of loss of the control signal from the
transmitter. After 0,5s of detecting a loss or invalid RC signal, the ecu sets engine
power to idle, and if after another 1,5seconds a valid signal is still not received the
engine is shut down.
●LowRPM: The engine has been shut down because the RPM has dropped below a
minimum. Cause could be lack of fuel, air bubbles, problem with the batteries, or
defective RPM sensor.
●RCPwFail: Lack of power from the radio receiver.
Fuel System
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