Shokjet Manual
SHOCKJET ASSEMBLY MANUAL
MF MODELS 6/18/09
Wingspan
Length
Weight
Turbine
80.5”
73”
13 lbs
Super Bee 14 lb thrust
turbine or equivalent
Table of Contents
Specs........................................................................................................................ 1
Parts Needed........................................................................................................ 2, 3
Nosewheel Installation.......................................................................................... 3, 4
Turbine Installation................................................................................................ 5, 6
Tail............................................................................................................................ 7
Wing................................................................................................................... 7, 8, 9
Important Notes....................................................................................................... 10
Radio Setup............................................................................................................ 11
Turbine Starts........................................................................................................... 12
1
Introduction
This product was originally designed by MF Models. Development was a joint effort between MF Models and Troy Built
Models USA.
If this is your first turbine powered aircraft and you need basic information, please see the Troy Built Models website and
review the turbine overview webpage. This will provide you with a quick overview to make your turbine flying experience
more enjoyable.
The intent of the ShockJet is to offer an inexpensive plane which will help newcomers to turbines aircraft get accustomed
to the nuances of turbines. The ShockJet is easy to build, fly and land. It is very aerobatic, so it is more fun to some pilots.
Once you are acclimated, you can move the turbine and other ancillary equipment to a higher performance or a scale
aircraft and sell the ShockJet for close to what you paid for it. A larger version of the ShockJet is being considered to accommodate larger turbines for those pilots who have their eye on a larger plane to move the equipment into in the future
rather than the planes that the current turbines will accommodate.
This plane, like all planes, can be broken if the design limits are exceeded. Flying at top speed, at full throttle and pulling
extremely tight turns will put great stress on the airframe, and eventually it will fail. The plane is designed for spirited flying
but not for pylon racing.
Installation of the components is very straightforward. We find it easier to first install the turbine, then the interior components, then the landing gear and finally the tail section.
Parts Needed
Turbine: We recommend a 10 - 18 lb turbine. The engine rails have the blind nuts pre-installed for the Jet Central Super
Bee. The Jet Cat P-60 fits with minor modifications. For more power a Jet Cat P-70 can be used however a few modifications are necessary because it is ¾” larger in diameter. The advantage of the P-70 is that it provides equal power to
weight when the fuel tank is full.
Fuel Tank: The fuselage accommodates a 50 oz Dubro tank which offers 7-9 minutes of flight time with the Super Bee.
You may also purchase a Kevlar Fuel Tank made for the Shockjet from Jet-Tech. (Shown below)
Bubble-less Fuel Tank: Because the plane is very aerobatic, we recommend the TBM BFT to keep bubbles out of the fuel
line. The kit includes a BFT mount and the fuselage has a space to accommodate the TBM BFT.
Fuel Line: A few feet of kerosene compatible fuel line is required for the main fuel tank and overflow.
Festo 6mm tubing clear - 2 meters (6’) From BFT to fuel pump and fill line
Festo Fittings:
Over flow fitting
Festo 6mm cap for kerosene filling
One way valve for propane filling
Safety Wire: for the many fuel and gas connections
Servos: 7 Hitech 645 and 1 Hitec HS 225MG (brake) or equivalent.
Servo Extensions:
6” servo wire, 2 for flaps in wing, rpm sensor, throttle
12” servo wire, 1-elevator servo, 1-flaps in fuse, 1-ailerons in fuse
24” servo wire, 2-ailerons in wing, 1-rudder
2
48” servo wire, 1-elevator
12” Y-harness, 1-flaps in fuse, 1-ailerons in fuse, 1-rudder/steering
Battery: There are many options, the safest being 2 batteries and 2 switches, though this is generally the heaviest option.
4000 mah is necessary for 8-10 flights including start up and cool down. We recommend only the safest option which is
a 4000+ mah battery with two switch leads which has sufficient burst to power the turbine start motor (Lipoly of Li Phos
is better than Li Ion). For the SuperBee we recommend a TBM 4-cell square Li-Ion with 2 JR and 1 Multiplex leads. The
JR leads go to two MPI Miracle switches for charging and checking, and the Multiplex goes to the turbine ECU.
Switches & Regulators: We recommend 2 though the reduced vibration is much less damaging to the electronics on
board.
Loctite: Even though vibration is minimal, we recommend using a thread locker for any metal to metal screws.
Epoxy: to join the wing halves
Cable ties, Foam Rubber & Velcro: to hold the receiver and cables in place.
Do not join the fuselage together yet.
GLUE EVERYTHING AND ANYTHING WITH THIN AND THICK CA
1)
As will all ARF’s, you should go over every joint. First use thin CA, then use thick Ca in every joint that you can
reach.
2)
WING HOLD DOWNS IN FUSELAGE: Be sure that the balsa blocks and the plywood under the balsa blocks
which act as the wing hold down blocks in the fuselage are well glued. Add hardwood triangle, ply or square stock (not
included) as an extra precaution.
3)
Look inside the wing through the inspection hole. Enlarge if necessary. If there is a visible gap between the rib
and the sheeting, contact TBM. You may not notice glue in the joint, this is typical. Only if there is a visible gap is there an
issue. It is a good idea to squirt a thin CA into the inspection hole to be sure that what you see is will glued. The center
wing spar and the first inner ply rib are important to the structure of the wing. It is better to use a little extra care to avoid
a problem later.
4) Test all the hinges by pulling on them and flexing them to see if they are loose at all. Reglue all the hinges if there is any
question as to their integrity. Use thin and thick CA as required. Usually one or two drops of thin CA and possibly one drop
of thick CA if there are any gaps is required. MF Models is not responsible for crashes due to hinge issues.
Nosewheel Installation
1) Assemble the nose wheel bracket with tire and brake as shown on the package and
the photo here. The bracket is a common part. The brake was added to the package
later.
2) Install nose wheel bracket as shown. If you have a 2 piece fuselage, install the bracket before joining the 2 halves of the fuselage.
3) Install brake servo (Hitec HS-225).
4) Install steering servo
5) In the photo on the left, the nose of the plane is pointed to
the left. Use this orientation for the coil springs in the nosewheel,
brake arm and paddle. This orientation is necessary for the springs
in the nosewheel to coil up properly when the brake is used, or if an
obstruction in the runway is encountered.
6) The brake is more effective when the spinning tire comes up into the brake as shown. The Kevlar
cable is connected to the brake servo with a spring. The spring is inside the fuselage. The spring is
required to mask and irregularities and wear in the system and to reduce the strain on the servo. The
spring must be fairly strong because the force exerted onto the tire must be high enough to almost 3
lock the tire up completely.
Due to the low landing speeds achievable with this plane, a brake is not necessary, but it is a requirement by AMA, and it
is very handy! Use the hole in the servo arm which is the closest to the servo shaft. Very little movement is required, and
this puts less strain on the servo and battery.
7) Connect the Kevlar thread directly to the servo arm. Then inside the fuselage, tie the spring to the thread keeping the
spring inside the fuselage when the brake is fully released. Glue in a piece of small diameter fuel or gas line as a guide
for the thread. Tie the thread to the brake arm. Do not load the servo excessively or it will burn up. Gluing 400 grit sand
paper to the brake paddle will increase the friction if necessary.
8) Install servo steering arm as shown but do not lock into place yet. Once the main gear is in place, you must set the
angle of attack of the wing with respect to the ground by ad¬justing the height of the nosewheel.
When building a one piece Shockjet you will need to use a long tool to screw in your nose gear mounting block. Please
review the pictures below to learn a way of getting to the screws through the bottom of the Shokjet fuselage.
Parts Needed
JOIN THE FUSELAGE HALVES TOGETHER
1)
Trial fit the two halves together.
2)
Once satisfied, use epoxy to attach the halves.
MAIN GEAR INSTALLATION
1)
Bolt the tires to the main gear
2)
Use the 4 bolts supplied to bolt the main gear to the fuselage with screws and nuts provided.
3)
All the tires need a few drops of Thin CA to glue them to the rim, or they MAY roll off of the rim.
4
Turbine Installation
Please see Page 6 for pictures referenced in this section.
1) Install the battery as shown under the front hatch. Route the wires forward towards the switch.
2) Install the components in the front of the fuselage. We suggest keeping the wiring
neat by running as many wires as possible under the floor as shown. Installing the
BFT and main fuel tank after this is done makes it a lot easier to pull wires under the
floor, because you will use those holes to gain access to the wires.
3) When installing the turbine, the glow plug must be in easy reach in case it needs
to be changed at the field. We prefer to reach it by removing the wing. We have
provided a hole in the top as shown for this purpose. You can opt to reach the glow
plug from the bottom of the fuselage if you prefer.
4) Use a soldering iron to open the 4 holes in the covering as shown for access to
the turbine.
5) Use the 4-40 screws and blind nuts. The blind nuts are already installed for the
Super Bee. Just set in place and install screws..
6) If you use a larger turbine, you may remove the bottom of the fuselage to fit the
turbine. You can install new rails for mounting the turbine. Be sure they are well fixed
to the fuselage. The use of a larger turbine voids the warranty unless the turbine is
turned down in the ECU to 14 lbs thrust, or the weight of the plane, whichever is
less. BE SURE to keep the angle of the turbine mounting rails the same as before. The turbine is at the proper angle for
the plane to fly properly.
7) Install the switches. Shown is only 1 switch, though there is room for 6 switches side by side. This is left to your preference. Only one battery pack is required to operate the plane, though installation of 2 battery packs provides redundancy.
8) Install regulator and Rx as shown
9) Install fuel pump as shown. Be sure it is pumping the correct direction.
10) Install kerosene and gas valves as shown
11) Install propane tank as shown if you have one. Note the 4mm Festo one way valve for filling.
12) Route the wires and tubing along the right side of the fuselage and on top of the tank being sure that nothing can be
sucked into the turbine, and nothing blocks the air inlets into the fuselage.
13) Install fuel valve between pump and valve as shown
14) Install ECU as shown
15) Install BFT as shown. Note the 6mm Festo cap used for fueling. Below is the BFT mount.
16) FUEL TANK – No fuel tank is included with the kit. Install a 50 oz Dubro fuel tank (or equivalent) using the Velcro
straps. Install a wood block behind the tank to keep it from sliding back¬wards. A larger capacity Kevlar tank is available.
A 101 oz PE tank is also available.
17) Route the wires and tubing along the right side of the fuselage and on top of the tank being sure that nothing can be
sucked into the turbine, and nothing blocks the air inlets into the fuse-lage.
Glue 2 Y-harnesses to the side of the fuselage as shown. Mark them as ailerons or flaps. Connect them to the receiver. Be
sure that the wires from the wing to here are short enough that they can¬not be sucked into the turbine.
5
6
Tail Section
Tail Section:
1) Installing the fin and elevator is a simple matter of applying epoxy
to the surfaces and gluing them in place. Before gluing, be sure that
the fin is exactly centered in the fuselage. Use a square to ensure that
the fin is perpendicular to the stab. Use the corner stock provided.
2) Install the control horns as shown
3) Install the servos and servo arms as shown. Use servo extensions.
4) Trial fit carbon fiber rods to pushrod ends to make elevator and
rudder pushrods. When satisfied, glue pushrod ends in place with JB
weld. Install as shown.
Wing
Fig 2
Fig 1
Fig 4
Fig 3
Fig 5
7
INSTALL FRONT WING BOLT REINFORCEMENTS
1) The existing mounts can crush if the front wing bolts are over-tightened. The addition of the dowel eliminates this issue.
Please do not over tighten the wing bolts. The front wing bolts are recessed into the wing .700”. These holes in the top of
the wing are 3/8” in diameter. These must be reinforced with 3/8” hardwood dowel rods 3/8” long (Fig 1). The bolts are
still recessed into the wing, just not as much. Make sure the dowel is seated completely otherwise the wing bolts may be
too short. Install one dowel into each wing half. Do one wing half at a time.
2) Open up the one hole in the covering IN THE TOP of each wing using a soldering iron (Fig 2). Do not open the bottom
hole yet. Feel around for the hole in the wood under the covering. The hole is about 2 ¼” from the root and 1 ¼” from
the leading edge.
3) Insert one 3/8” wood dowel into the hole from the top. Be sure it is seated down well. Put several drops of thin CA into
the hole to soak the entire area. Repeat. Once this dries, if there are any gaps between the dowel and the hole, fill with
thick CA and accelerator (Fig 2).
4) Open the bottom of the front wing hold down. This hole is only 7/32” in diameter, much smaller than the top (Fig 3).
5) Soak the hole with thin CA. Repeat. (Fig 3)
6) When hard, redrill the hole for the front wing bolt from the TOP of the wing using a 11/64” drill bit (Fig 4). After joining
the wing, you may need to open the hole with a larger drill bit, up to 7/32”. Just open the hole a little at a time until the
bolts in the wing line up with the bolts in the fuselage. Once the holes are set, install the steel washer into the wing, and
glue in place with thin CA.
REINFORCE REAR WING BOLT HOLES IN WING
1) Open up the BOTTOM hole in the wing for the rear wing hold down bolt using a soldering iron. The hole is about 7/32”
in diameter. Do not open the TOP hole yet. It is about 2” from the wing root and about 5/8” from the trailing edge of the
wing. (Fig 5)
2) Put several drops of thin CA into the hole. Repeat a few minutes later.
3) If you feel that is it is thorough soaked with thin CA, then open the TOP hole in the wing using a soldering iron. Then
re-drill the hole using an 11/64” drill bit. Later you may need to open the hole slightly to meet up with the wing hold downs
in the fuselage. This is a hardwood dowel, though the soaking with CA helps. If you find that the wing is crushing when
installing the wing hold down bolts, the addition of a larger washer is prudent.
1)
PUT IN WING SERVOS
Install the flap and aileron servos before joining the wing. Pull the wires through the hole available. Mark the wires as being flaps or ailerons to avoid confusion when setting up at the field. Be sure that these wires are long enough to reach
to the Y-harnesses in the fuselage, but short enough that they cannot be sucked up into the turbine. While you could put
Y-harnesses for the flaps and ailerons in the wing itself, we don’t recommend it. If you have a problem with a servo and it
requires replacement and the Y-harness is in the wing, it’s hard to reconnect.
2)
Clean the aluminum with alcohol. Lightly sand the aluminum, especially the edges, not just the sides, with 100
grit sandpaper to roughen it.
3)
Shape and install the plywood pieces in the center of the aluminum wing spars. Glue the inserts into the wing spar
using Hysol. Do not install into the wing yet.
8
4)
Dry fit the wing halves together using the spar. When satisfied, apply Hysol to the wing joiner and mating surfaces.
Be sure that the entire spar is covered with Hysol. It is especially important to get glue on the edges of the spar, not just
the sides. Gluing the aluminum spar to the wood spars above and below the aluminum spar is critical. Set the top of the
wing down (servo side up) onto a flat surface to allow the Hysol to cure. No dihedral is desired. Actually, a little anhedral
is best.
5)
Install the control horns and servo arms as shown. Plastic servo arms can be used if you keep the servo motion
maximized and the control surface deflection minimized.
6)
The ailerons should move a maximum of 30 degrees (or as much as possible)
7)
The flaps should move as much as possible (about 70 degrees).
8)
Note in the photo(Page 8) that three of the 4 servo arms point to the right and one points to the left. This is
necessary to avoid the use of a reversed servo if using a Y-harness. The hard points are located in the wing for this configuration, so don’t change from it.
SETTING UP THE ANGLE OF ATTACK:
The angle of attack of the wing with respect to the ground when the plane is at rest must be set properly for easy take
offs and landings. The wing has 2 degrees of negative angle of attack with respect to the stab, so do not set the angle of
attack on the ground relative to the stab, use the wing.
The angle of attack on the ground is easily set by adjusting the height of the nosewheel.
If the angle of attack of the wing is too great (positive 2 degrees or more), the plane will lift off with a very short take off
roll. It may take off in less than 3’ if there is much of a breeze.
Fortunately the plane is stable and this is not an issue for an experienced pilot. The downside of excessive angle of attack is
shown on landing. The plane flies very slowly, and thus the plane will hop and bounce unless the speed is bled off perfectly.
The opposite is true for too little angle of attack (negative 2 degrees or more). The plane needs more airspeed and thus
more runway to rotate, but still it will rotate far sooner than most any other turbine aircraft. If the angle of attack is really low
of course it will never take off. However, upon landing, even at modest speeds, the nose will stick down onto the pavement
and remain planted very easily.
9
Important!
Before your first flight, and before the first flight after and
changes or repairs, be sure that there are no loose foreign
objects in the fuselage which can be sucked into the turbine.
Hold the fuselage without the wing upside down and at various
angles and shake it to remove any foreign debris.
CG
The CG is as shown. Your CG points can be found 3”(wing off)
and 1½”(wing on) in front of the landing gear with about a ½” of play. Depending on the batteries used, you may need to add lead to the nose or tail, or relocate a
battery. The plane is very forgiving. We like to adjust the CG after the first flew flights. We
see how much down elevator is required when the plane is inverted. If it is more than you prefer, then adjust the CG. The
further back the CG is located, the less down elevator is required to fly inverted. Moving the CG back excessively will not
allow the nosewheel to have much effect on the ground. Instead of braking the plane, the nosewheel locks up and skids,
so don’t go too far aft with the CG
Radio set up.
Following is the set up used in our JR radio.
Rudder to Aileron and Elevator Mix: Due to the high stab, high rudder and high wing, the plane has proverse roll and pitches up with rudder. This can be easily mixed out. Please do so as soon as possible and leave these mixes on at all times.
Trimming for pitch: The top of the fuselage and stab are defined to be 0 degrees. Thus the angle of attack of the wing is
2 degrees negative (down in front). The angle of incidence of the turbine is 6 degrees positive (up in front).
10
Radio Setup
Following is the set up used in our JR radio.
Rudder to Aileron and Elevator Mix: Due to the high stab, high rudder and high wing, the plane has proverse roll and pitches up with rudder. This can be easily mixed out. Please do so as soon as possible and leave these mixes on at all times.
Trimming for pitch: The top of the fuselage and stab are defined to be 0 degrees. Thus the angle of attack of the wing is
2 degrees negative (down in front). The angle of incidence of the turbine is 6 degrees positive (up in front). These incidences were determined through extensive testing. These are important to keep the plane from climbing at full throttle. If
your plane climbs or descends with throttle you have a few options.
One option is to change the thrust angle of the turbine by adding a washer or 2 between the turbine mount and the
mounting rails. Adding the washers in the back will push the back of the turbine down more and will reduce the plane’s
tendency to climb at full throttle.
Another option is to put washers between the wing and the fuselage. Raising the back of the wing will again reduce the
plane’s tendency to climb at full throttle.
A third option is to mix down elevator with throttle. This is my least favorite because of throttle lag. When you go from idle
to full throttle, if down elevator is mixed with throttle, the plane will dip before the plane picks up speed and then flies level.
Flaps: We recommend taking off with ½ flaps, about 35 degrees of deflection. This shortens the take off roll out and
makes the plane climb out more easily.
We recommend landing with the flaps deflected as much as possible. The flaps are bottom hinged to obtain a lot of movement. The flaps should deploy by 70 degrees or more. This allows for ultra slow landing speeds. We use the standard flap
switch. We have 2 degrees down elevator mixed with take off flaps, and 7 degrees down elevator mixed with full flaps.
This is a good starting point, your plane could differ slightly.
Brake: There are several options as to which switch to use. We use the trainer switch as well as a mix switch so that the
brake is available to both hands. We flip the mix switch on to hold the plane in place when starting, and use the trainer
switch when the plane is on the runway. You can elect to activate the brake just before landing so that the brake is on
during landing and the roll out is short. Avoid excessive servo strain. Glue 400 grit sandpaper to the brake paddle if necessary to reduce the servo strain. Initially set up the brake so that it is very difficult to move the tire by hand with the brake
engaged. Then roll the fuselage on the ground in the driveway and test the brake. Adjust as necessary.
Ailerons: We set up the ailerons to move 30 degrees and use 70% expo.
11
Turbine Starts
Start tube: We made a start tube from plywood and 3” diameter dryer vent
from Home Depot. During the start up process fire may belch out from the
turbine and catch the plane on fire. The bottom of the plane is covered with
aluminum covering which is fire resistant, but just to be safe, we recommend the use of a start tube. Drawings are available at no charge if you
would like to make one for yourself.
Start ups must be into the wind: When starting the plane, the turbine is
spinning slowly, and there may be an excess of propane, thus creating
a fire. It is important for the flames to be carried towards the back of the
plane. If the wind is blowing from the rear, the flames can be carried forward, starting a fire under the wing. Thus all start ups must be into the wind, and a start tube is recommended for each
and every start up. If you do not use a tube, you run the risk of a hot start and burning the tail of your airplane off!!
Hot Fueling: If you plan to fly several flights, it may not be necessary to shut the turbine down between flights. It is much
better for the turbine and the battery to do a hot fuel. Just fuel the plane with the turbine running. Each time the turbine is
shut down it goes through a heat cycle where it goes from ambient temperature to hundreds of degrees. Hot starts reduce
the heat cycles. More battery is used during shut down than at any other time. The battery cycles the starter motor for
several minutes to cool the turbine. Hot fueling eliminates this cycling of the starter motor.
Good Luck and be safe!!
TROY BUILT MODELS
1650 Honore Ave. - Sarasota, FL 34232
941-342-8685
http://troybuiltmodels.com
12
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising