the United States or owned by US companies. The European
market is the next largest, with growing activity in
the Middle East, Asia, and Central America. The current
focus is to develop the low end of the market with small
models that are far cheaper than today's business jets.
this month's issue of AMP'D, we look at several lower
cost scale jet models that not only use Electric Ducted
Fan (EDF) power but fly Business Class!
Hobby Lobby Executive Jet
twin ducted fan jet on the right is designed by Super
Flying Model and sold in the U.S. by Hobby
Lobby International. It is made from molded-bead foam
construction, has a 47" wingspan, and meant to fly at
around 47 oz. or 3lbs. The model resembles a Learjet 45XR
with the lower dart fins on the tail. The larger engine pods
are typical on an EDF powered R/C model.
fuselage comes with two 66mm ducted fans that are pre-installed
and ready to mount the motors. The wings are reinforced with
carbon tubes and have molded recesses for the aileron servos.
The wing tips are made of wood and come pre-covered. The bottom
of the wings have molded pockets with plywood mounting blocks
for the included fixed landing gear or you can upgrade to
the optional retract gear set (SFM3501B)
with steerable nose wheel.
Exec Jet assembly was quite easy since there were very few
parts in the kit. I added the optional retracts to my model
which also require several more servos.
the bays were ready to accept servos and retracts but the
fuselage bottom needed to be cut for the nose wheel. A template
is provided for tracing the right cut outline.
ailerons, elevator and rudder are made of balsa and covered
with heat-shrink film. They are pre-installed and the hinges
are pre-pinned for safety. The fuselage has wooden servo mounts
and battery tray pre-installed. The model is powered by two
3s 2100mAh packs.
power system was upgraded from the stock 3-blade rotors to
the well balanced Wemotec 504 rotors while still using the
stock pre-mounted fan units. Ductedfans.com
sells a nice Dual Rotor Upgrade Kit (WE504ex2)
for this purpose. The Wemotec rotors and adapters allowed
me to use the 3.2mm shaft AMMO 28-35-3900
Brushless Inrunner motors to double my power level over the
stock 2.3mm shaft SFM Outrunner motors.
Although the retracts worked fine, I did not feel that they
would work on grass take-offs and landings. I knew the SFM Exec
Jet could easily be hand launched so I prepared the plane for
belly landings in grass by coating the bottom with a layer of
20-minute finishing epoxy from Bob Smith Industries.
On foam planes like the Exec Jet, coating the nose tip, leading
edges, and ends where there are no decals helps protect the
model from bumps and rash with only a minimal increase in weight.
Executive Jet was ready for taxi testing in a nearby parking
lot. The March weather was sunny but still cold and the flying
soggy flying fields would not be open for another month or
so. We were just happy to see the snow was gone.
SFM Exec Jet taxi testing went very well. I did find that
one of the retracts was not properly locking down but that
was fixed with a simple servo travel adjustment on the transmitter.
In a future issue of AMP'D, I'll show some flying photos and
a video with both a hand-launch and pavement take-off from
newer "Version 2" Hero
100 Twin EDF Executive Jet from Nitro
Planes is a larger 71" span semi-scale Cessna Citation
II fiberglass model aircraft. This twin-EDF model was designed
around dual 101mm fan units and matched D36-2200kv brushless
motors. Created for the advanced sport scale pilot, the Hero
Eagle 100 ARF is designed for easy assembly and setup using
quality wood construction with a fiberglass fuselage.
The removable front hatch also allows for easy access to the
radio equipment and batteries. The entire trim scheme is pre-painted,
and the the wings are covered in quality shrink material.
Most of the decals have already been applied and all hardware
and accessories are included.
Wing span: 71 in / 1803 mm
Wing area: 746 sq in / 48.4 sq dm
Flying weight: 14.3lb / 6500g
Fuselage length: 71 in / 1803 mm
EDF : 101mm / 4.0 in x 2pcs
Radio Required: 6-channels, 8-servos
Brushless Motors : D36 x L 50 mm , 2200 kv
Speed Controllers : 22.2 v ; 85A
Li-poly Battery : 4000mAh ; 25C
Hero 100 Cessna 550 comes in a big 68" long box. The
plane looked well packed and the parts were either wrapped
in foam or plastic.
split the box photos in half to get a closer look. The fuselage
spans the entire length of the box.
wing halves measured 31.5" each. All the wood surfaces
were perfectly covered without a single wrinkle. This was
unexpected quality from a $200 ARF of this size.
control surfaces, like ailerons, rudder, and elevator halves,
all had the hinge material inserted but needed to be glued
with thin CA.
main wing tube measured 27.5" across. I discovered another
addition to the Version 2 kit, there were three wheel retract
bays instead of two on the original kit.
kit came with a decal sheet and a 10-page glossy manual with
clear photos. The decal sheet includes both scale decals (that
I plan to use) and non-scale decals for the model name.
manual appeared to be for Version 1 and shows using a steerable
non-retractable nose wheel. This option, along with the wheels,
still comes with Version 2 for those that don't build it with
retracts. There is no cutout on the bottom of the fuselage
in the manual and the canopy section has been crossed out
with pen marks.
I think what you get for only $200 is a great value and I
was excited to finally start this project after a 6 month
wait for it to return to stock. There are certain pitfalls
with these lower cost fiberglass models from China but they
can easily be overcome with some experience and skill. I will
address these issues along the way.
Fuselage - A Closer Look:
large one-piece fuselage was 68" long. Most of the colors
and decals had already been applied. I decided that I would
be modifying the color scheme to closer match the full-scale
Cessna Citation that this design mostly mimics. More to come
on the scale-up process.
formers, retract bays, and servo/battery bay appeared to be
intact but I recommend doing a full inspection for strength
of adhesion to the fiberglass body. I typically use the aerospace
grade epoxy called Vpoxy
from BVM Jets to ensure a quality bond between fiberglass
and other materials like wood or plastic.
the addition of the nose wheel retract cutout and retract
bay in the Version 2 kits.
was an odd 90 degree twist in the cutout and matching well.
Since my plan was to use Spring Air 301 retracts with Robart
struts, I needed to make some changes.
Cessna Citation II PH-LAB
Hero Eagle 100 was modeled after the full-scale Cessna 550
Citation II research aircraft from NLR
in the Netherlands. The Cessna Citation II PH-LAB
is one of the research aircraft operated by the National Aerospace
Laboratory NLR. It is owned and operated jointly with the
Delft University of Technology, Faculty of Aerospace Engineering.
Originally designed for executive travel, this Citation II
has been extensively modified by NLR and Delft University
of Technology to serve as a versatile airborne research platform.
full-scale Citation II is a twinjet aircraft of conventional
aluminum construction. It can accommodate up to eight passengers
(or observers) in addition to the two-pilot cockpit crew.
The plane's registration, PH-LAB, is derived from the Netherlands
designation of PH (like N for USA) and the three letter call
sign LAB for Laboratory. The flying laboratory's primary purpose
is to teach students what it takes to do measurements on dynamic
flights, sometimes in zero-G conditions, and as a platform
for atmospheric measurements all over the world.
non-scale colors of the Nitro Planes' Hero 100 appear to be
from combining schemes of several Cessna Citations together.
The yellow appears to be derived from the international Aeromed
Medivac Cessna Citation II; N174DR.
colors like the bright red across the leading edges were likely
chosen to increase orientation in the air. I'll be changing
some of the shrink film colors on my wing and tail as well
as removing the yellow from the fuselage.
navigation lights for the Cessna 550 are the EDR-117 LiteSys
Dynamics. This plug and play lighting system for scale
models uses the ED-SunVis Wide-angle lamps that are visible
in sunlight. The dual RC Switch can either turn the lights
on whenever the receiver hears the transmitter or by a spare
channel. I'm using the LiteSys Starter System with Transmitter-controlled
switching for $119. It includes the following items.
and Green Nav Lights
Beacon or White Strobe (select)
retract choice is the Spring
Air 301 Firewall Retract Set. These retracts use air pressure
to go up and spring force to go down. I have successfully
used this brand in the past on my Byron A-4 Skyhawk and feel
they offer a good quality value with a great fail-safe mode
of operation. If you loose the air pressure, the retracts
lock down in the landing position. Carl Rich also proved that
these retracts were a good size choice on the Version 1 Cessna.
The 301 retracts can handle models up to 15-16lbs.
of using the supplied wire mains, I'm using a pre-enjoyed
set of Robart 501 struts with Dubro (275TL) 2-3/4" Treaded
strut can be easily added by making your own 5/32" pin
with a Dremel tool. The struts not only reduce bounce on landing
but enhance the gear appearance by eliminating the skinny
power system components will be the following items...times
original plan was to use Wemotec Midi Pro fans. When I received
the new RC Lander 90mm metal DFs, I was very surprised at
the quality of the machining. Further, it fit perfectly into
the Hero 100 nacelle and was a great color match! I didn't
have any measurements on the fan performance so I needed a
way to compare it with the Midi Pro rotor. RC Lander also
makes clam shell mounts for these 90mm DFs so it will easily
mount onto the platform in the nacelle.
RC Lander rotor is only 5-blades compared to the Midi Pro
6-blade rotor but it does have a more aggressive pitch so
perhaps the loading and thrust may be comparable. The rotor
is made from some composite that is very hard and the quality
was very high so that I did not see any flaws.
made the following weight measurements.
2-piece fan housing = 3.1oz
spinner, and adapter = 1.4oz
tail cone = 1.6oz
are some photos of the RC Lander 90mm DF using the Wemotec
Midi Pro rotor and spinner. The 6-blade Midi Pro rotor is
on the left and then mounted in the fan. The shaft size and
adapter screw are the same so it fits right on the Lander
adapter. The Midi Pro rotor length is slightly smaller than
the Lander rotor length by about 4mm.
looked promising for a reasonable load on 8s LiPo with the
Neu motor. If not, then the Midi Pros will provide a known
2500 watts per side with great efficiency.
measured the distance needed from the nacelle to the ESC (mounted
in the fuselage) and extended the motor wires by 6" of
#10 Castle Creations wire. This would also allow me to mount
the assembled nacelle first and then connect the motor wires
to the ICE 100 ESC via the bottom hatch opening in the fuselage.
new ICE 100 ESCs had built-in data logging so I could easily
take my power, current, and RPM measurements while measuring
the thrust on my new low-cost thrust stand, shown below. The
6mm gold bullet connectors on my LiPo packs could now plug
directly into the ICE 100 ESC without the need for an external
in-line wattmeter, which can sometimes damage ESCs due to
the added inductance. For more information on this incredibly
useful feature from Castle Creations, go here.
Castle Creations Data Log showed that I was right on target
with a full throttle reading of 90amps and 2400 watts. The
37.1K rpms proved that the Neu 1415/1.5Y inrunner motor is
really spinning that 90mm rotor! I changed the PWM setting
from the default of "Outrunner" to 12KHz as a middle
of the road setting that should not make the controller too
hot. The little blips on the charts before the full throttle
tests were from me giving a small throttle movement to check
the system after the Spektrum receiver sync lights came on.
only $14 at Harbor Freight and another $19 at Gander Mountain
Sporting Goods, I created a $33 thrust stand with some additional
scrap plywood. The Rapala Digital Fish Scale can read up to
50lbs or 25kg without any movement of the chain. I simply
removed the casters and reversed the long planks so that the
flat side faced the inside. The drawer slides were mounted
with the supplied screws and then held with a custom base
meant to hold a 90mm EDF. I initially secured the Rapala scale
with large wood screws to make my measurements but I will
likely make it removable in the future so that I can also
use it to measure the installed system in the plane.
full throttle, my scale read about 6.5lbs static thrust. Although
this may not be too accurate without a thrust tube in place,
it was a good sanity check that allowed me to move forward
with the RC Lander DF and rotor.
first step of assembly in these larger low-cost fiberglass
models is always inspection. While I was surprised at the
wrinkle-free covering, I was not surprised to find some loose
is always best to take some time at the beginning of a project
like this to stress test all the parts that come in contact
with the fiberglass. Even if you do not find loose formers,
I still recommend running a bead of a quality epoxy like the
from BVM Jets. Another popular brand is the Locktite Hysol.
fix loose areas, the proper procedure is to first tack glue
the area with medium CA, let it dry, and then run a bead of
VPOXY preferably on both sides, although this is not always
possible. There are different length mixing tubes available
for the gun or you can mix it yourself before applying it
to the surfaces.
next step of the assembly is to complete the wings. The Spring
Air 301 retract installed easily after first making some minor
cut adjustments. I also noticed that with a little modification,
you could mount the flap and aileron servos sideways for a
cleaner look. I used JR DS821 digital servos because they
offer strong torque and great return to center for a reasonable
flap servo mounted sideways after a few cuts with a Dremel
tool and a small block of balsa underneath to raise it up
flush with the surface. The aileron servo needed a tray running
between the two ribs. I used a scrap piece of light plywood.
To extend the servo wires, I used JR (JRPA102) 24" Heavy
Duty Servo Extensions.
plug and play navigation light easily mounted on the wing
tip after drilling a hole from the end into the long open
bay that travels the length of the wing.
drilling a hole from the wheel well into the main bay that
runs the length of the wing, all four lines could exit the
normal opening that goes into the fuselage without further
I looked at the supplied hardware, I knew that I wanted to
mount the control horns on the bottom side only for a cleaner
look on the top of the wing. The control surfaces were plenty
thick so I used the supplied wood screws instead of the intended
machine screws that were meant to pass through the control
surface. By pre-drilling some pilot holes for the control
horns and using some CA, it created a strong hold that could
not be seen from the top. I didn't think there was a long
enough block in the flap for the outer most screw so I cut
an opening in the covering and added a small piece of plywood.
issue I had with the hardware was that the threaded ends of
the aileron and flap control rods were too small for the plastic
clevis. I used my own metric control rods from an old bulk
I bought from Hobby Lobby years ago. Since these control rods
also came with a metal clevis, I used those instead of the
supplied plastic clevis.
that remains to do on the wing is to cover the red and yellow
sections. This will be saved towards the end of the project.
yellow on the fuselage was re-painted with Valspar Gloss White
(102S) Spray Enamel paint. First, the black lines were masked
off and then the yellow area was sanded with #220 grit sandpaper.
I then taped paper towels over the rest of the fuselage before
spraying. Several coats of paint were needed.
burgundy (maroon) color line will be painted in the center
between the two black lines. The color will be close to the
burgundy covering used to eliminate the remaining yellow on
the control surfaces.
mounting the Lander DF unit in the nacelle, I added an MPI
Heatsink for 36mm motors. These low-cost heatsinks simply
press into place and keep your motor cooler which helps add
longevity. Also before mounting the DF, I added extra epoxy
to the mounts in the nacelle.
discovered that there was a thrust offset in the nacelle motor
mount that made the DF point away from the fuselage. I centered
the thrust line by using some washers in the aft end of my
Lander clam-shell mount and slightly recessing the front end
with a Dremel tool.
nacelle cover was temporarily taped into place. The fit was
not great so it will require some cutting with the Dremel
tool before being finished. I'll also be adding some exhaust
tubing for an 85% FSA. With a setup of 2400 watts per nacelle,
I can sacrifice some thrust for added speed.
finishing the second wing, I was able to install them on the
fuselage using the two aluminum tubes. The larger diameter
and longer tube needed to be cut shorter about an inch before
the wings would butt up against the fuselage. The fit seemed
pretty good so I secured the wings to the fuselage using the
supplied bolts and wooden washers.
used a piece of foam to position the nose at the proper angle.
This length can be used to check the nose wheel distance from
the fuselage when installing the retract.
that I used a reverse DS-821 digital servo on the second flap
in order to utilize a single channel by using a Y-harness.
The second aileron still used a standard DS-821 servo since
it needs to move in the opposite direction. Both flaps use
a single channel and both ailerons use a single channel.
the nose retract, I wasn't quite sure what the manufacturer
had in mind. Not only was it intended for a 90 degree rotating
retract but it was also cut off center. The pre-installed
4mm t-nuts did not match the footprint of my SpringAir 301
retract so it was time for some changes.
decided to use one of my articulated-knee Spring-Shock struts
from Golden Skies
R/C. For only $27 each, this well-made strut can handle
models up to 16lbs.
first cutting the bridge away on the second former, I re-located
the 4mm t-nuts for the SpringAir retract and corrected the
center line. I used my foam piece from the previous step to
help determine how long my 5/32" music wire pin needed
to be. Both the Spring Air 301 retract and the Golden Skies
R/C strut are made to accept the 5/32" wire.
order for the wheel to retract into the fuselage, I opened
the bottom up a bit using a Dremel tool.
finished up the nose retract installation by adding three
pieces of plywood for additional strength. Two square pieces
bridge the two formers and a third triangle piece runs from
the first former forward. The whole assembly was now very
steering retract was a Futaba S3115 mini servo. The metal
linkage was short, easy to adjust, and wobble-free. It is
important to keep the white swivel horn on the SpringAir retract
in line with the retract joint so that the wheel does not
turn as it retracts.
used a mix on a spare channel to the rudder in my Spektrum
9503 transmitter. The same mix also disables itself when the
gear switch is in the retracted position so that rudder movement
does not turn the nose wheel during normal flight.
The nose retract, servo, and linkage are not part of the Cessna
kit. The epoxy I have been using is 3M Scotch-Weld DP-110.
I had several tubes on hand so I decided to use it up. It
has a 9-minute worklife and is similar to V-poxy and Hysol
but has a yellowish color instead of white or clear.
next step in the assembly was to mount the stabilizers so
it was time "to get the red out". I covered the
cherry red sections of the stabilizers with maroon Monokote
and used 3M Scotchcal Striping Tape to blend in the joints.
The burgundy colored striping tape comes in 3/32" and
3/16" widths and is available at most automotive detailing
re-painted yellow stripe on the fuselage was also detailed
with the burgundy Scotchcal tape.
the horizontal stabilizer fit well on the fuselage, the vertical
stab wasn't even close. Further, you can see that the rudder
covering does not match the vertical stabilizer...suggesting
that kit parts from Version 1 and 2 may have been mixed. It
didn't take much effort to make it work. As long as you expect
some issues on these low-cost fiberglass ARFs, you are prepared
to make adjustments. I also enjoy making small enhancements
along the way.
elevator servos were installed in their normal positions but
since the nose wheel retracted into the rudder servo position,
I re-positioned it further back and down by the fuselage.
I made some servo holder blocks from one of the unused stock
gear mains mounting blocks. Note that one of the elevator
servos is a reverse servo so that only a single channel is
need for elevator control.
three long control rods had the same fit issue as before when
using the supplied clevis. I took one to my local hobby shop
and they measured the threads as 2mm with a .4mm pitch. This
meant that I could use some Dubro 2mm hardware.
I purchased some #819 Dubro 2mm Safety-Lock Kwik-Links for
my tail connections.These Kwik-Links worked perfectly with
the rest of the stock hardware.
installation technique was to keep the control horns on the
bottom side which made for a clean look from the top side
of the Cessna. I used some medium CA into pre-drilled pilot
holes and mounted the stock control horns using the supplied
wood screws that are just the right length to not push through
to the other side of the control surface.
plastic control rod sleeves were epoxied in place and then
mounted the right nacelle using the supplied M4 screws and
t-nuts. My kit had no Mylar for the thrust tubes so I picked
up some .020" thick Duralar at a local art supply store.
I knew the nacelle exit would be large for my 90mm power system
so I wanted a thick tube that could stand on its own without
any support. The Cessna application is not all that weight
borrowed the thrust tube photo from my Nitro Predator UCAV
project and changed just the length dimension to 9.25".
Since both applications used 90mm EDFs, the ends of the tube
are the same for the desired 86% FSA. I usually cut the tube
a little longer and then trim it to where I want it later.
nacelle cover wasn't a perfect fit but it wasn't bad for this
Castle Creations ICE
100 ESCs fit nicely on the bottom of the fuselage. By
cutting the right size rectangle in the fiberglass, you can
pop the ESC into place using the built-in heat sink as a holder.
The ESCs protrude just slightly so they can get some cooling
air during flight.
mounted the second nacelle like the first. The covers didn't
fit all that well and made me wonder if they were original
version 1 parts on version 2 nacelles. Since the new plastic
canopy fits great on the fuselage, I would have preferred
some better fitting plastic nacelle covers instead of the
ill-fitting fiberglass ones. The nacelles fit great against
the fuselage and I saw no thrust offset.
support all my digital servos and navigation lights, I decided
to use the new CC
BEC Pro from Castle Creations. It provides 10-amps continuous
current and 20-amps peak on a wide range of supplies from
3s to 12s Lipo. Further, it can be programmed from 4.8v to
12.5v using the CastleLink software and only weighs an ounce.
It allowed me to use any of my smaller 3s LiPo packs, around
1AH, as a receiver pack.
CC BEC Pro fit nicely under the battery tray and connects
to my 3s Lipo pack without using a switch. It has two output
lines going to servo connectors that can handle up to 5-amps
each. This was a perfect mate to my JR R921 9-channel 2.4GHz.
receiver that has two battery inputs for redundancy.
also mounted my EDR-117 LiteSys controller next to my receiver
as it was time to mount the strobe light and the gear light.
Note that the wires have increased in quantity. I plan to
clean them up after my initial checkout of the control surfaces
Batteries and Strobe Light
two 4s Blue Lipo 4AH packs seemed to fit well in the area
provided. In addition to Velcro on the bottom, I used a wide
Velcro One-Wrap strap as a safety belt. This strap also helped
secure the wires underneath the tray.
white strobe light was too difficult to mount on top of the
vertical stab so I positioned it on top of the fuselage. The
very bright flashing strobe can be seen from any direction
around the plane. I'll likely save mounting the last white
nose gear light until after my taxi testing.
plastic canopy was cut out from the mold to fit well on the
fuselage. I then epoxied a dowel and block to the canopy front
and drilled a mating hole into the fuselage. By using dual
hatch latches, one on each side, it held the canopy in place
fairly well. The latches were secured with Plasti-Zap after
first sanding the contact surfaces.
found the white hatch latches for sale on the RCU Marketplace
for $6 each. Hobby Lobby also sells the HLRE001
for $5 each.
increase the hold so that the front ends would not flap in
the air stream, I created a balsa frame for the front of the
canopy. This technique allowed the canopy to be easily removed
while keeping it secure during flight.
Bottom Hatch and CG
bottom hatch opening wasn't quite square so I needed to trim
some of the corners on the cover before it would properly
screw into place.
this photo was taken, I marked the CG location on the fuselage
bottom at 106mm back from the leading edge. This was 31mm
forward of the suggested CG in the manual but proven to be
a better choice by Carl Rich.
was time to focus on changing the color scheme and adding
The stock yellow and red colors were replaced with burgundy
and flat black vinyl covering that was purchased from a sign
shop. The sticky-back covering was easier to apply without
wrinkles than the initial Monokote shrink film I used on the
there are several versions of full scale PH-LAB Cessna, I
choose to mimic one that allowed me to use most of the supplied
decals. By first cutting away the clear sections with a razor
knife, the decals apply much easier without wrinkles or bubbles.
had the "Delft University of Technology" decals
made special by RCU's Matt Kirsch.
initial taxi test on pavement went very well. Although I never
went above 1/3 throttle, the Cessna Citation seemed ready
to go. All the control surfaces worked smoothly and I powered
up each 8s system using my anti-spark 100ohm resistor that
had proven successful in several previous projects.
now majestic looking Cessna Citation II taxied without effort
on pavement. My plan is to fly it off a grass field so we
will see how much runway is needed when the 4800 watt power
system is a full throttle.
that remains is to create the air retract control board and
cut the thrust tubes shorter. I will likely add a few more
scale details as this is a very fun part of our hobby!
I was nearly finished my Hero 100 assembly, I took a photo
of it in a similar pose to the stock model. I was happy
that it finally looked like a scale Cessna Citation II model
and not a toy.
Hero Eagle 100 was modeled after the full-scale Cessna 550
Citation II research aircraft from NLR in the Netherlands.
By making a few simple color changes and adding some scale
items like retracts, struts, and navigation lights, you
can transform a lower-cost model to look like a much higher
end scale replica.
the PH-LAB is one of several research aircraft of the NLR,
I will likely add the PHARUS radar pod under the belly after
the initial flight testing.
this summer, a future issue of AMP'D will cover the Cessna
flying performance with photos, video, and an internal GPS
speed reading. This same issue will also include the F9F
Panthers from my previous column...so stay tuned.
you fly electric, fly clean, fly quiet, and fly safe!
thanks for contributions by:
"Papa Jeff" Ring and Paul Weigand
- the Ultimate Control System in One Device