choices for EDF are both vast and exciting when you start
to venture off the beaten path. EDF enthusiasts that want
to advance faster than the current mainstream market allows
must find other power system components and host planes from
a variety of smaller vendors.
power EDFs and Do-It-Yourself conversions aren't for everyone
as they can push the limits of today's technology, and your
skills, so these projects are usually best suited for the
you want a larger model with more power or maybe a good building
fix, you don't need to spend thousands of dollars on an R/C
model. With the right skill set, and attitude, you can create
something impressive enough to get noticed at any flying field.
focus in this month's issue of AMP'D is to show some higher
power EDF models that, without breaking the bank, can be flown
off grass, have functional retracts, and provide enough thrust
to make that awesome jet sound!
Models F-4 Phantom-II
F-4 Phantom-II is a large foam EDF model. It is one member
in a series of Styrofoam EDF jets from FlyFly
Hobby. These models are distributed overseas by Hobby88.com
or here in the U.S. by Electric Jet Factory (EJF.com).
you are not familiar with FlyFly Hobby foam jet models, they
are uniquely engineered designs that are made from EPS foam.
The large jets are designed for 90mm EDFs and fit together
like a precision 3D puzzle piece. They come with the ducted
fan unit and fixed landing gear. They can be hand-launched
over grass or fitted with optional retracts.
favorite way to power these 90mm FlyFly models is to use the
following components. I replace the FlyFly rotor with a more
efficient WeMoTec MidiFan rotor and keep the perfect fit of
the FlyFly DF in the model. The Great Planes AMMO inrunner
motors have worked very well for me and the Castle Creations
ESCs truly meet their rating. I also use a quality LiPo pack
like the Enerland 30C series Lipos.
general, these big foam kits are easy to build and fly. I
protect the outer surface with a coating of Bob Smith Industries
20-Minute Finishing Epoxy. They provide a good host for a
larger, more powerful 90mm EDF system and look great in the
video above shows a hand-launch of the FlyFly F4 Phantom
II and just how versatile it is in the air. From loops,
rolls, flying inverted and fast fly-bys, the F4 Phantom
II is a nice step up in size and power over the smaller
RTF foamie jets.
EDF Predator UCAV from Nitro
Planes is a large low-cost fiberglass jet model with sheeted
wings. The full-scale Predator is a medium-altitude, long-endurance
Unmanned Combat Aerial Vehicle. The Predator is used in areas
where enemy air defenses have not been fully suppressed, open
ocean environments, and biological or chemical contaminated
environments. These machines, armed with Hellfire missiles,
were used successfully in Afghanistan proving the advantages
of the UCAV concept.
Nitro Planes Predator UCAV comes complete with fixed landing
gear, fiberglass canopy, missiles, and all hardware. The model
can be powered by a 90mm to 101mm (3.5" to 4") EDF
unit. On sale, I have seen this model sell for as low as $120.
Top quality wood construction
Fiberglass fuselage and canopy
Sheeted built up balsa and plywood wings
Comes with hardware and accessories
Wing Span: 47.2 in / 1200mm
Wing Area : 521 sq in / 33.8 sq dm
Flying Weight : 6.6 lb / 3000 g
Fuselage Length : 58.7 / 1490 mm
4-Channels Radio System Required
5 Servos Required
power system for the Predator UCAV is a WeMoTec Midi
Pro 90mm EDF for 5mm shafts, Medusa Research MR-3680-1100V2SE-5
Inrunner Brushless motor, Castle Creations HV85
ESC, and two 6s Enerland
(30C) 3200mAh LiPo packs in series. The motor was a great
fit for high-powering a low-cost 90mm EDF and at only $150.
On a 12s LiPo supply, it can provide burst power up to 3300
watts at 74amps current. This delivers 7lbs of EDF thrust
for a powerful 390w/lb. All these components, except the motor,
can be obtained from Hobby
fiberglass canopy is pre-finished and only needs the latch
mechanism attached. The landing gear are fixed with a steerable
nose wheel assembly. Two sheets of finishing decals are supplied
and the 7-page manual, although sparse, provides sufficient
photos and text to complete the model by an experienced assembler.
closer look at the fuselage reveals the size, quality finish,
construction techniques, and high level of pre-assembly. The
T-nuts are already installed, and glued in place, for the
gear mains and steerable nose wheel assembly. The battery
and servo trays are also pre-installed. It is always a good
idea to check for bad glue joints where the formers meet the
fiberglass and high stress areas like the gear mains and EDF
modelers fall into traps with these lower cost models from
China. Without realistic expectations, an improper attitude
to complete the project may not be a recipe for success. That
being said, you should expect some missing parts, some not
so great fits, and glossed over details on assembly and proper
CG placement. Plan to utilize your full skill set.
the proper expectations and skill set, you can feel confident
that you bought at least a decent shell for much less money
than other models on the market.
gluing in a pair of 2-1/4" long hardwood slats, the Midi
Pro fan fit perfectly in the ducted fan bay. I'll be using
the air intake ring that comes with the Midi Pro fan because
the bay area opens into a large area.
HS-81 servos fit perfectly in the plywood bay frame opening.
I secured 36" HD extensions to the control lines by first
tying the connectors with Firewire fishing line and then covering
them with shrink wrap. The lighter .6oz HS-81 servos will
provide 42oz/in torque on my 6v CC BEC.
main landing gear mounted very well without any issues. The
holes were pre-drilled in the fuselage and T-nuts already
mounted in the former. I only needed to cut off the excess
axle length with a Dremel tool. However, the steerable nose
gear installation was not as easy. The hole for the gear wire
was not marked on the fuselage so I installed the plastic
piece inside the fuselage first since the T-nuts were already
installed. I used a long rod with a sharpened end to press
through the gear wire holes on the plastic piece to create
an aligned hole from the inside to the outside. The hole was
then opened with a 11/64" drill bit.
the holes in the plastic piece also needed to be opened. I
used a 1/8" bit for the screw holes and a 11/64"
bit for the gear wire. The smaller nose wheel hole was also
opened with an 11/64" bit. Once installed, it allowed
me to finally sit the Predator UCAV on its own wheels. It
is not a bad idea to replace the stock nose wire with some
real 5/32" steel music wire. Du-bro makes a very nice
(#154) 5/32" Universal Nose Gear Wire with 4 coil turns
for added shock absorption.
that the Medusa V2 motor wires come out at a right angle for
an easy exit through the exhaust tube. The motor shaft also
has a flat side for the set screw on the Wemotec Midi Pro
5mm adapter to keep it from spinning under high RPMs. The
power system measurements are from Carl Rich. (12s LiPo, 75amps,
3333 watts, 200mph e-flux)
installed 4mm gold bullet connectors between the motor and
ESC. The main power lines got 6mm gold bullet connectors so
they don't get hot enough to melt solder. I will make a series
adapter with Dean's Ultra connectors for each 6s LiPo pack
and 6mm bullet connectors going to the CC HV110 ESC.
the 100 ohm resistor used for anti-spark connection on the
12s supply. This worked very well on my larger 4500 watt Byron
EDF conversion. Also note how well the 36mm (diameter) x 39mm
(length) heat sink fits on this setup. All my new models (including
reviews) that are 6s or higher voltage will have the anti-spark
feature added. I buy the 100ohm, 1w resistors on-line at Newark
Electronics for 5 cents each and there is no minimum purchase.
Radio Shack is another good place to obtain the resistors.
You can get all the anti-spark details in the Ask AMP'D section
of issue 2 of AMP'D called, Arming
the Big Boys.
Wemotec Midi Pro EDF is the industry leader for efficient
90mm fans. Although the Pro rotor itself can still be used
in other ducted fans, I have found that the Wemotec EDF is
the easiest to assemble of the 4 manufacturers I have used.
a complete build thread on the Predator UCAV, go here.
Nitro kit does come with a nice piece of thick Mylar so I
cut it down to 90mm size using the same FSA ratio as in my
bent the motor wires at a right angle to plug into the CC
HV85 ESC without hitting the wall. The wires are also twisted
so that they are flat in-line with the Wemotec mounting tab.
This allows for an easy slice out of the Mylar to make the
exhaust tube fit.
Spectrum AR7000 dual receiver was mounted to the side with
strong power systems using two packs in series, I use a separate
receiver pack (2-cell 1500mAh LiPo) and a Duralite (DUR65060)
6v regulator with a fail-safe switch for safety.
had been warned by other modelers that the battery (or batteries)
needs to be placed behind the nose gear servo in between the
two air intakes. It seems obvious that the manufacturer had
never tested the design with EDF. I have seen this several
times before on other designs from overseas so I thought about
decided to build a battery box that allowed the packs to easily
slide in place and have holes for some cooling. The battery
packs will be secured with a Velcro strap across the top.
The battery box partially blocks the air intake openings but
they seem large enough to make the blockage insignificant.
My initial setup used two FlightPower EON28 6s 3350mAh packs
Test Flying the Predator UCAV
Nitro Predator UCAV was Ready-To-Fly at 8.5lbs. The empty
plane weighed 100oz (6.25lbs) and my two 6s EON packs weighed
36oz (2.25lbs) together. The 3300 watt power system provides
a powerful 390w/lb!
had some good success with our first test flights on the Nitro
Predator UCAV. The power system was awesome and had no problem
taking off grass. After landing hard on the first few flights,
we moved the CG from 7.25" to 7.75" and had much
easier take-offs and landings.
Predator flew very stabile, even when it was flown slower.
The EDF jet performed loops and rolls with ease. We discovered
that when landing, you need to carry a certain speed or the
plane will pitch up if it lands too slow. The pitch-up is
due to the fact that the V-tail stops flying first when the
air flow is low and simply drops.
did permanently glue on the wings for added structural integrity.
The rather soft landing gear act as shock absorbers on those
less than perfect landings and they are easy to bend back
in place after first removing them from the fuselage. We left
the nose gear bent backwards as it seemed to still take-off
and land well until I finally replaced it with the Dubro 5/32"
Universal Nose Gear Wire. The coil spring in the nose gear
still works when the gear is bent back.
second video shows continued success with the Predator UCAV.
Perhaps over the winter, I'll look into
up the gear mains mount and replacing the stock nose wheel
with a retractable Robart strut.
fact that the aluminum gear mains bend upon hard impact is
a real plus as it absorbs those less than perfect landings.
Predator UCAV was a very fun project and exceeded my expectations
for a larger EDF model without breaking the bank.
Byron A-4 Skyhawk was originally built about 18 years ago
by Dominic Cognata (RCU's "Major Woody") and flown
with an O.S .91 glow engine. At one time, these high-end kits
were at the top of the R/C world but are now considered outdated.
The stock 6" diameter Byron fan put out between 10-12lbs
of thrust. The air intake openings for Glow Ducted Fan (or
GDF) are larger than needed for turbine-powered jets but are
a great fit for EDF. The new EDF components available today
weight similar to their original glow-powered counterparts
but the power system can now deliver about 15lbs of thrust
for improved flight performance.
Byron jets like my A-4 Skyhawk can be purchased at auctions
or through R/C clubs. They make a great host for a higher
powered EDF conversion without breaking the bank. New kits
and spare parts can still be purchased from the Iron
Bay Model Company. I have found the best approach to contact
them is to keep calling them on the phone until someone answers.
plane was in good shape but required some minor repair and
upgrades. All the servos were replaced with JR DS-821 Digital
Sport Servos and the elevator and rudder controls were re-designed
using short linkages with the servos in the tail. The 72MHz
receiver was replaced with a Spektrum AR7000 2.4GHz dual receiver.
The nose gear got a Robart strut upgrade and the slimy exhaust
tube needed to be replaced.
Byron A-4 was originally flown with the O.S. 91 engine shown
on the right. The new EDF components weighed slightly less
than their original glow-powered counterparts but it was not
significantly different. The glow engine and fan weigh in
at 1.5lbs. When we added the tuned pipe, Rx. battery pack,
Byron duct unit, extra servos for throttle and fuel mix change,
we eliminated over 3.25lbs not counting the slimy exhaust
tube, 24oz fuel tank and 2oz header tank. All in all, we estimate
removing about 5lbs for the GDF power system.
new power system for my A-4 uses an E-Turbax ducted fan unit
Hangar International. It is powered by a Neu 1527/1.5Y
motor, Castle Creations HV110 ESC, and two 6s Enerland 5050mAh
LiPo packs. The Byron conversion with the Neu 1527/1.5Y motor
on a 12s LiPo produces about 4500 watts.
E-Turbax unit assembled quite easily using the supplied instructions.
The only difference is that the tail cone is no longer supplied
as it was an expensive custom carbon piece that had no real
benefit on the air flow.
was impressed with the machined quality of the E-Turbax fan
and consider it an excellent value for this type of product.
EDF test stand was once again modified for the larger 120mm
unit. It had been previously used to test 70mm and 90mm setups.
I extended the motor wires using 18" of #10 gauge Castle
Creations silver wire and connected them to the CC Phoenix
HV110 ESC using 6mm gold bullet connectors.
initial testing, I'm using a gold Dean's Ultra connector for
the two 6s packs in series. I haven't seen a problem in the
past when passing 95-100amps through them but this application
may be at a higher current for longer periods than my other
applications. I had been warned that others have melted the
wires off the Dean's Ultra connectors, when used in higher
power EDF setups like this one, so it is best to use 6mm Gold
initial low RPM testing with a single 6s pack was very successful
and exciting! I then upgraded my HV110 ESC to the latest software
over the Internet using the CastleLINK USB Interface and disabled
the brake function. The packs shown are very old Kokam 6s2p
20C 4200mAh packs that have seen plenty of use. The old FMA
BalancePro HD connectors kept the packs healthy over many
years through balanced charging. I initially used these older
packs to see what happens on a 12s setup in my EDF test stand
as I was waiting for some of the new chemistry Enerland 30C
packs to arrive.
decided it would be easier to paint my canopy frame flat black
rather than try to match the grey paint from 18 years ago.
I used inexpensive spray enamel from Valspar called "Odds
N Ends". It is available from Michael's Craft Stores
or Home Depot for only $3 a can.
replaced all the servos with JR DS-821 Digital Sport Servos
and eliminated the long nyrod linkages. The old Byron Skyhawk
now has the rudder and elevator servos in the tail with short
metal linkages. We also installed a Robart 656
Straight Robostrut w/Fork and used a solid rubber Robart (225TL)
Treaded Lightweight wheel for the nosewheel. I added some
spacers to eliminate any side-to-side movement of the wheel.
By mounting the servos in the vertical stab, it stopped the
fin sides from being able to come together or spread apart,
eliminating any flex.
installing the wings, I rubbed some silicone lubricant onto
the rubber seals that plug into the fuselage sides to connect
the air line. After pumping 100lbs of air pressure into the
tank, the old SpringAir retracts came back to life!
plywood collar was made to close the gap from the original
Byron GDF 6-1/2" opening down to the E-Turbax 5-1/8"
opening. Initially, I tried using some 1-1/2" long aluminum
channel stock (in 4 pieces) above and below the EDF bracket
but decided that the two 2-1/2" steel brackets I bought
at an Ace Hardware store for $0.79 each would work better
and easier. The motor wires will route between the former
and fiberglass body like the existing servo wire.
modified a new Byron thrust tube from Iron Bay Model Company
to fit the smaller diameter needed for the E-Turbax. The dimensions
are as follows:
DF end 4.88" diameter (x Pi = 15.3" circumference)
Output 3.75" diameter (x Pi = 11.8" circumference)
5" hose clamp will hold the thrust tube in place around
the EDF and a hole will be cut about an inch back from the
motor to drop the wires through.
that an output diameter of 3.5" would favor top end speed
while a diameter of 4.0" would favor thrust. The recommended
compromise between thrust and speed is 3.75". This is
where I decided to start and see just how much of our 600'
long field length is needed for take-off. The Byron A-4 does
not have flaps.
close the gap between the thrust tube and the fiberglass body,
I made a custom "ring" of foam that fills the gap
and stabilizes the tube. I cut a 1-1/2" wide plastic
ring from a CD case cover which is about 5" in diameter
and then custom glued it to just fit around the 3-3/4"
thrust tube end. I then glued a thin 1-1/2" strip of
foam to this thicker plastic ring made from the CD case and
pressed it in place. In this manner, the thrust tube does
not get distorted by the foam. It is held by double-side tape
between the plastic ring and the thrust tube so it cannot
held down the control and motor wires with some homemade balsa
pieces and CA. The other set of servo control wires is held
in place with some 3M cord clips. The CC HV110 ESC is secured
by both a Velcro plywood plate and a Velcro "seat belt".
I can pick up the entire jet by the ESC so it is secured well
and resides in the secondary air flow out of the way of the
primary air flow for power.
the wires were secured, I created an air intake scoop from
a large plastic funnel I bought at an Ace Hardware store.
The scoop directs all air from the 9" fuselage to the
5-1/8" E-Turbax opening. The photo shows it sitting in
position but not yet mounted.
safely power the A-4, I used a Duralite
Flight Systems 6v regulator with a built-in fail-safe
On/Off switch. The regulator supplies 6.0 volts at 7.5amps
continuous current with spikes up to 10amps. If the switch
fails, the regulator remains on.
regulator is fed by a 3oz, 2-cell Kokam 1500mAh pack which
I modified to use the FMA Cellpro Multi4
my two 6-cell Enerland 5050mAh packs will be charged by two
10s chargers. These chargers provide safe balanced charging
at up to a 3C rate. My 6s 30C packs can be charged at a 2C
rate on the Cellpro 10s charger for a 30-minute charge time.
came up with a convenient way to arm the 12s LiPo power system
on the Byron EDF conversion which eliminates any spark. By
touching the 100ohm 1w resistor lead to the + side of the
HV110 ESC and then sliding the 6mm gold bullet connector in
place, the spark is eliminated. The main red ESC wire sits
in a safe channel so it doesn?t move around but the exposed
resistor wire can also be easily covered with a piece of tubing,
once the system is armed. The paper in the photo is positioned
to make the connectors easier to see.
like this can be purchased at many places. Mine cost $0.053
from Newark Electronics On-line.
Newark Part No: 71M1113 1w Metal film resistor.
new generation Enerland (PolyQuest) 6-cell, 30C, 5050mAh packs
promise increased cycle life and performance. Since they can
deliver up to 150amps continuous and 200amps burst, I will
not be stressing them in my Byron EDF conversion that draws
only 95amps at full throttle. The new packs should be available
larger #8 gauge wires on these Enerland packs fit my 6mm Gold
bullet connectors perfectly. I found another source for these
connectors at Tower Hobbies. Great Planes GPMM3116
Gold Plated 6mm Male connectors and GPMM3117
6mm Female connectors. Another nice improvement is the single
node connector for a 6-cell pack. The balance node connector
plugs in perfectly to my FMA Cellpro 10s charger using the
Flying the converted Byron A-4 Skyhawk
the Byron A-4 was ready for test flying, I measured the following
Main Fuselage = 145oz (9.06lbs)
Wings w/Retracts = 44oz (2.75lbs)
Two 6s 5050mAh Enerland Batteries = 51oz (3.2lbs)
plane without e-fuel was 189oz (11.8lbs). The total RTF weight
was 240oz (15lbs). The thrust was equal to the weight which
was an improvement over the original glow-powered system.
Lynn Bowerman, and I had a great day test flying the Byron
A-4 EDF conversion with the new Enerland 30C 5050mAh packs.
The power level was excellent! I used 6mm Gold Bullet connectors
on the packs which eliminated the Dean's Ultra connectors
and the need for a series harness. The 200-amp rated bullet
connectors allow you to simply chain packs in series and the
95-amp draw at full throttle would not produce enough heat
to melt the solder connections.
several successful taxi tests on grass, we decided to let
it fly! The Byron A-4 seemed well balanced and even landed
very well. On one of the taxi tests or take-off, the nose
gear wire was bent back but it didn't affect the ground performance.
were a short 3 to 4 minutes as we were pushing the A-4 hard
in the wind. Higher capacity 6AH packs may provide more stick
time but we are not sure what effect the extra weight would
have on the A-4 handling. The nose gear bent aft again but
didn't seem to affect the ground handling at all. I ended
up replacing the metal pin going into the retract mechanism
and used a slightly larger 2-1/4" Dubro wheel.
we were pleased with the EDF conversion performance on the
Byron A-4 Skyhawk. It flew better than it ever did with the
original glow-powered engine and we see about 135mph speed
using an internal GPS device.
about 15 flights, we continue to have success with the Byron
EDF conversion. The trickiest part is landing without flaps
(and no breeze) because there is about a 5mph window that
makes or "breaks" a successful landing. Perhaps
we will add some flaps to it over the winter. One of the photos
below shows the proper alpha landing position where it touches
down nice and sweet. We "clocked it" with an internal
GPS device at 135mph. After the 10th flight, I added a silver
fuel tube for an added scale touch.
the 55mm to 70mm RTF foam jets are very popular and provide
a great way to get into EDF flying, the choices become more
confusing for those R/Cers that want to step up in size
and power. Some very nice jet models exist for those with
the means but you need to do some serious searching if you
want a lower cost option. If you select a lower cost model
from overseas, without realistic expectations, an improper
attitude to complete the project may not be a recipe for
success. Do some research on the forums and plan to utilize
your full skill set. With the proper expectations and skills,
you can feel confident that you bought at least a decent
shell for much less money than other models on the market.
This month's issue of AMP'D revealed some larger, higher
powered EDF models that could be hand-tossed or provide
enough thrust to be flown off grass. These few examples,
although meant for the experienced modeler, were all a great
deal of fun to build, modify, and fly, without breaking
you fly electric, fly clean, fly quiet, and fly safe!
thanks for contributions by:
"Papa Jeff" Ring, Lynn Bowerman, and Devin McGrath
section of AMP'D cover some of the questions that our
readers have sent in and I thought would be interesting
like the smaller RTF foam EDF jets but only have
a grass area to take-off and land. Can any of
these smaller jets take off from grass?
brought my Hobby Lobby F-4
Phantom to the flying field on Labor Day weekend
to test its ability to take off grass. As you
can see from the video below, it can easily take-off
from grass and taxi back to the pits. This is
an amazing foam EDF design!