through Horizon Hobby
4105 Fieldstone Rd.
Champaign, IL 61822
Phone: (217) 352-1913
US Aerobatic Team pilot and manager Frank Christensen's
attempt to buy the Pitts aircraft line failed, Frank
decided to start his own aircraft company; Christensen
Industries. The design for the Christen Eagle
was based on the extremely popular Pitts Special.
The two place Christen Eagle II is an Unlimited Aerobatic
Class aircraft intended to be used in aerobatic competition
or advanced aerobatic flight training.
wanted to develop a high performance home built aircraft
that could be used in competition but that anyone
could safely build and fly. No special skills
are required to assemble the Eagle, in fact the full
scale is a kit that comes in numbered sub-assemblies
much like our models. The kit set a new standard
for home built aircraft and includes factory welded
parts, tools, jigs, and a 30 volume assembly and maintenance
a testament to the Christen Eagle II meeting Franks
design goals, the Christen Eagle II boasts a 90 percent
completion rate of the over 1000 kits sold to date.
Eagle II made its debut at the 1977 Oshkosh, WI EAA
Fly-In and immediately gained popularity with amateur
and professional pilots alike.
260HP single seat Eagle I's were built specifically
for the Eagles Aerobatic team and painted in the distinctive
8 color eagle scheme. Intended only for prototypes,
the difficult scheme was in great demand by many home
builders and soon available with the kit. This
world famous trio (Gene Soucy, Charlie Hilliard, and
Tom Poberezny) flew the Eagle on the air show circuit
from 1979 through 1995.
had the pleasure of reviewing the Hangar 9 Almost
Ready to Fly recreation of the famous Christen Eagle
II. The ARF can be constructed with either a
glow fuel powered engine or an electric power system.
Our Eagle will be equipped with the Saito 125 four
stroke glow engine and JR/Spektrum radio components.
Let's get started!
courtesy of WikiPedia
Full 8 color factory scheme
Ready for electric or nitro motor installation
Cowl matched covering
Highly detailed pilot and cockpit are pre-painted
and pre-installed (but see misses)
Outstanding covering job.
Typical H9 manual
Large access hatch will make battery changing a snap for
Innovative wing transport makes field assembly very easy.
Quality hardware kit includes everything you need.
Engine mounts accomodate both glow and electric motor installation.
Pilot figure is glued to covering and not wood, pulled loose
just handling the canopy.
have always loved biplanes and was excited to find out
I would be receiving the newly released Christen Eagle
II from Hangar 9.
Christen Eagle II was designed from the ground up to
be an every day sport flyer and can accept a variety
of power systems. I built mine with the great
sounding Saito 1.25 four stroke engine but a battery
tray and motor mount are included for installing an
electric power system if wiping some oil off at the
end of the day isn't your thing. I like electric
power and have several electric planes but the Eagle
really deserves the quiet pop pop pop of the Saito 4
my Christen Eagle II arrived at the door the box appeared
as though it had been run over with a fork lift.
I held my breath as I peeled back the layers but was
pleasantly surprised to find that due to the nice packaging
job and a bit of luck, there was no damage to anything
but the box.
The model appears to be very well built out of balsa
wood and lite-plywood and covered in UltraCote.
The 8 color Eagle scheme is faithfully represented in
UltraCote rather than many of the models I've seen
with only 4 color graphics. All of the markings,
including the N number are applied at the factory but
a sheet of logos is included in case you want to personalize
your Eagle. The covering job was excellent though
as with any kit making a long journey, a few edges needed
to be sealed and a few sags removed. In all I
spent about 30 minutes with a covering iron going over
everything that appeared to need it.
noted, the packaging appears excellent and resisted
the best efforts UPS to inflict any damage upon it.
All of the parts are wrapped in plastic and the hardware
is separated and bagged. Opening up the contents
a few things stuck out right away. All sharp edges
like the aileron control horns on each wing, and the
canopy latches were covered with foam blocks to prevent
them from stabbing holes in covering. This kind
of attention to detail is what I've come to expect
from Hangar 9 offerings.
cowl and wheel pants are constructed of fiberglass and
appear sturdy without being heavy. The wing joiner
tubes included in the kit are constructed of aluminum
and appear up to the task. The cockpit is finished
with both front and rear seat instrument panels, and
a painted pilot figure installed. (NOTE: Take
the time to secure the pilot figure by drilling some
small pilot holes and running a couple of servo screws
up through the bottom.) About the only thing
I found that I felt might not be up to par were the
very thin landing gear fairings that were constructed
of ABS plastic. Even when attached with clear
silicon adhesive so the joint was flexible, both fairings
cracked on the first flight.
With all of the parts laid out it was time to sit down
and read the instruction manual.
manual for the Hangar 9 Christen Eagle II is exactly as
I have come to expect from my experience with Hangar 9 models,
that is to say, it's outstanding. The well written
manual is photo illustrated at nearly every step and includes
measurements and building tips as required.
manual covers everything that I think is essential for a
great manual: a complete inventory, concise instructions,
clear photographs, center of gravity, control throws, and
most importantly product support contact information.
always make a habit of checking online to see if there are
any updates or addendums for the manual of the kit I'm
working on but as of this writing none were available for
the Christen Eagle II.
when building or repairing a nitro powered airplane, always
use thread locker on ALL metal to metal connections!
I had my work area laid out I set up a new model in my
JR 11X DSMX 2.4gHz radio and bound it to a Spektrum AR8000
DSMX receiver. The 11X (as well as several other
of the high end radios) makes setting up multiple servos
for one control a snap with the surface mating feature.
The Eagle uses 2 aileron servos so using the mating feature
eliminates setting up a Y-harness or program mix and ensures
that any trim or mixing applied to the master channel
affects each surface equally. Having the radio
ready to go allowed me to set up each control surface
as the build moved along.
first steps in assembling the Eagle involve getting it
on its feet. Bolting the landing gear to the fuselage
should be done with care because the cover is intended
to be glued on. I installed the bolts with Z-42
thread lock and glued the strut cover in place with clear
silicon so that it would be somewhat removable if maintenance
(aka straightening) was required later on.
strut fairings are made out of ABS plastic that is very
thin so take care while cutting them. Make the hole
for the strut large enough that the strut doesn't
directly contact the fairing and install them with clear
wheels and wheel pants all went together without any issues
following the instructions in the manual with one exception.
The measurement on page 8 step 8 is incorrect. Install
the wheel and then mark the spot for the flat spot that
will seat the set screw.
the tail is conventional and following the manual yield
a straight and strong airframe. The only personalization
I made from the process was to use a metal straight edge
to align the cut outs on the stabilizer and vertical fin.
pictured below left, Hangar 9 kits tend to pay careful
attention to detail. In this case, instead of leaving
the rear of the fuselage open where the elevator joiner
rod is, they included a small square of black covered
balsa to seal up the gap.
verifying proper alignment and doing a little bit of sanding
on the stab saddle, I used Pacer 30 minute Z-Poxy to install
the stabilizer and then the fin. The 30 minute epoxy
has plenty of working time to allow you to clean up any
mess with a clean paper towel and alcohol.
tail wheel looks to be of adequate strength and quality
for a model this side. It's secured to the rudder
via a tiller and nylon strap so as to avoid transmitting
the force of less than perfect landings directly to the
like the other building processes involved in getting
the Eagle ready to fly, the radio system installation
is simple and straight forward with one small exception
and that involves installing the throttle pushrod a little
will be using the JR DS821 Sport Digital servos for the
Hangar 9 Christen Eagle. With 88 ounces of torque
(when run on 6v) they should be plenty for the 90 size
Eagle. Supplying juice to the servos and receiver
will be a 5 cell 2700Mah NiMH JR battery pack. Guidance
duties will be handled by my JR 11X DSMX 2.4GHz radio
bound to an 8 channel Spektrum AR8000 DSMX receiver.
of using the usual phillips head screws to install the
servos I elected to use the socket head servo screws available
installing the servos don't forget to pre-cut the
threads through the wood first then harden the threads
with thin CA.
you use the recommended components you can go ahead and
mount the battery and receiver in the indicated positions
and the model will balance perfectly.
I set up my servos I always power up the radio to center
the servos without a control horn installed. Then
I fit the horn and rotate it 90 degrees at a time with the
intent to find the arm that is at or closest to 90 degrees
to the servo body. Then you can use the minimum amount
of sub trim needed to achieve perfect 90 degree alignment.
Mark the arm that gives you the best alignment and remove
the remaining arms.
that, make your final adjustments to the clevises on the
control rods to precisely center each control surface.
When everything is perfect use thread lock on the jam nuts
and tighten everything down. Then check it all again!
top of the airplane is very smooth and I found it difficult
to locate where the slots for the cabane struts were located.
I didn't want to poke around until I found them either.
What I ended up doing is shining a very bright LED flashlight
into the front cabin area and it illuminated the holes
perfectly. After that it was just a matter of cutting
away the covering and ironing down the edges with a trim
whole arrangement is pretty slick. Between the pockets in
the fuselage for the lower wing, and the way the cabane support
goes together, alignment of the wings and proper wing incidence
is assured. If you've never dealt with a biplane before,
it's important that the top to bottom wing incidence is built
as designed or undesirable flying characteristics will result.
Hangar-9 did a great job here.
Saito 1.25 Four Stroke Engine Installation
Christen Eagle II will work with a variety of power plants,
indeed the parts are even included for an electric setup.
That said, for a classic like the Christen Eagle, nothing
beats the sound of a 4 stroke glow engine. As the
specifications indicate, the new FA-125 from Saito weighs
in at 10 ounces less than the fabled 120 and swings an
APC 16x6 prop at 9000 RPM!
Fiber filled engine mounts are provided for glow engine
laser etched mounting template provided in the kit shows
proper mounting locations for the Saito 1.25.
makes installation easy, just tape the template in place
and drill the appropriate holes. The open area on
the top allows easy installation of the blind nuts.
the pilot holes are drilled, remove the template and drill
the holes to their correct size, install the blind nuts
and test fit the engine.
Saito could put 1.25 cubic inches of power
into a 1.00 size case. Not only is
the FA-125 lighter and more powerful than
the FA-120 it replaces, its unique size
allows modelers to apply its awesome power
to a wide variety of airplanes sizes.
It will work with anything from .90 size
sport aerobats all the way up to 1.20 size
sport and IMAC planes. As with most
Saito engines, the FA-125A is available
in a stunning Golden Knight version with
gloss black finish and gold-plated valve
Less weight combined with more thrust
10 ounces lighter than the FA-120
Turns an APC 16x6 at 9,000 RPM!
13mm Muffler threads
1.24 in (31.7 mm)
1.02 in (26.00 mm)
1.25 cu in (20.52 cc)
RPM Range: 1,800 - 10,000 rpm
Crankshaft Thread Size: M8 x 1.25mm
Weight: 24.69 oz
Only Weight: 21.87 oz
Weight: 2.89 oz
RPM Range: 2,000 - 17,000 rpm
Range: 15x7 - 17x6
Dimensions: 119 x 60 x 127 mm
Cylinder Type: Single AAC
Type: Dual needle
Type: Dual Ball bearing
Warranty- Horizon Hobby, Inc., (Horizon)
warranties that the Products purchased (the
"Product") will be free from defects
in materials and workmanship for a period
of 3 years from the date of purchase by
completing final engine bolt down, this is one area where
you can learn from my one area of frustration. Build
the fuel tank and drill the holes needed for the throttle
pushrod in the fire wall and fuel tank bulkhead.
I used a 3 line system, the clunk to the carb, the pressure
line attached to the muffler, and a fill line that hung
down by the muffler that I capped.
test the fuel tank before installing it! This is important
because you have to break things to remove it. Cap
all the lines and immerse it in water and give it a gentle
squeeze and look for any air bubbles fixing any leaks as
needed before final tank installation. If gluing the
tank in makes you nervous you can always put a couple of
eye hooks on the rear of the bulkhead and secure the tank
with rubber bands. Having pressure tested the tank
I was confident enough to glue it in but if it comes out
I'm going to remove that rear brace and use the hook
and rubber band method.
glue the pushrod guide tube in the firewall. Slide
the fuel tank bulkhead over the end of the tube and slide
it into position. Glue the fuel tank bulkhead and
brace in place and then the throttle pushrod guide.
After you have the tank installed, push the Z-bend on the
throttle pushrod through the throttle arm on the engine,
insert the pushrod into the guide, then bolt the engine
to the engine mount. Trust me, this is much better
than trying to get that Z-bend on the throttle arm after
the engine is mounted.
Hangar 9 P-51 style 2.75" aluminum spinner is an
option for the Christen Eagle but it really looks sharp
with it installed. An Evolution 16.x6 prop rounded
out the business end. The big Saito engines uses
a single prop nut to lock things down so the spinner adapter
allows you to bolt on the shiny spinner as well as acting
like a jamb nut. I did have to cut down the spinner
bolt, put a nut on it, cut it with a Dremel cutting disk
and when you remove the nut it will clean up the threads
the cowl installation I dug back into my RTL Fasteners
goodies and pulled out 4 bonded washers. These really
help in preventing both screws from backing out from vibration
and assist in preventing the screws from elongating the
holes in the fiberglass cowl.
the cowl and then use some manila folder stock to mark
the cut out for the high speed needle. I used a
high speed Dremel sanding disk to smooth out that hole
and make the exit hole in the bottom of the cowl as shown
in the instructions. If you're not using a remote
glow plug driver you will also need to cut a hole for
the glow driver. If you're going the external
glow plug driver route make sure you have the
used clear silicon adhesive to glue the air baffle into
the cowl to route air directly over the cooling fins of
the big Saito.
biplanes will ever be easier to manage than the Christen
Eagle II. Steel alignment pins are glued into the
interplane struts. Then a 45mm machine screw is
inserted through the wing that threads into the interplane
struts. Here again, to protect both the finish and
to prevent things coming loose from vibration I used bonded
washers on the 45mm machine screws.
the ailerons centered up using the radio system I installed
the upper aileron push rods. The silicon fuel line
will help keep the clevis from coming apart at the wrong
time and a little thread locker will help keep both the
clevis and the jam nut from rotating.
long wing tube goes on the bottom but I marked it with
a Sharpee marker with a couple of big "B"s so
didn't have to experiment at the field. The
aluminum wing tubes appear sturdy without being overly
of the wings is quick and easy and will make setup at the field
a snap. There's two wing rods, 3 2.5mm bolts, and two
aileron extensions. Hangar 9 provided laser cut and etched
wing caddies that attach to the wing sets with rubber bands.
Once these are attached, the wings can be removed as a left and
right assembly for easy transport yet quick assembly. This
means no taking apart the interplane struts and no removing the
top aileron push rods to transport or store the plane. The
Christen Eagle II isn't all that big though and will fit in
just about any SUV (I have a Honda Pilot) fully assembled.
CG was set in the middle of the recommended range per the instructions
on the top wing at the center where the cabane strut is.
The CG is just about the aft edge of the tank so I don't expect
the CG to change much as fuel is consumed.
I installed the canopy I noticed the latches were a little rough.
I put a drop of light machine oil on each side and after working
them back and forth just a bit they loosened up nicely.
The two latch system allows quick and easy access to the inside
of the fuselage so that the switch can be mounted in the radio
compartment and doesn't spoil any external aesthetics.
If I were flying an electrified version I would rate the battery
access as excellent due to the easy to remove hatch and large
the directional programming of my JR 11X DSMX was done as I went
along with the build I took a few minutes to sit down and verify
the control throws and setup my dual rates. With only DS-821
servos, programming is pretty simple and about the only feature
other than dual rates and expo that I used was the ability of
the 11X to assign a mate to the aileron instead of using a P-Mix
gave everything one last inspection and got ready to spend the
next day at the field.
9's careful design and attention to detail took care
of all that. Assembly at the field of the Chrsten
Eagle II consists of sliding the wings in place and removing
the transport caddies, connecting two aileron extensions,
and installing 3 bolts. The Eagle goes from broken
down for transport, to fueled and ready to fly in less than
5 minutes. About the same amount of time and effort that
it takes to prep any monoplane with plug in wings.
fueled up the Eagle with Byron Rotor-Rage 30% premium helicopter
fuel. My Saito 100 always loved the 30 percent and
it keeps me from toting around multiple fuel jugs.
The Saito started quickly with an electric starter and I
ran a tank on the ground to get the needles set and to check
over all of the fasteners for any signs of vibration.
After looking everything over carefully and setting the
engine a few clicks on the rich side it was time to get
some air under the wings.
the long tail moment of my Sbach or MXS I thought the Eagle
might be a bit of a handful on the ground. Taxi tests
gave me a sense that low rate on rudder would be desired
for takeoff and landing but other than that I was gaining
confidence in the Eagle. After dozens of takeoffs
though I can say that any trepidation on flying the short
coupled Eagle was unfounded. With a hair of up elevator
to hold the tail wheel down until the rudder becomes effective,
and smooth application of power the Eagle takes off like
any other sport plane. It does take some rudder to overcome
the P-Factor from the big engine, and if you lay the coals
to it quickly you had better hang on, a ground loop will
be in your immediate future, but if good tail dragger flying
proficiency is part of your skill set, you won't have
any problems flying this airplane.
the air the Christen Eagle is powerful, smooth and predictable.
It tracks well through large maneuvers and the Saito 125
has plenty of power for large loops, figure eights, and
immelmans. The engine has sufficient power to
sustain a hover but the control surfaces are made for sport
and aerobatic flying, and not 3D so it is hard to hold a
hover for very long. Also, due to the outboard location
of the ailerons there is no air blowing over them in a hover
so torque rolls come on quickly. A little bit of power
at the top of an upline though, and the Eagle will do gorgeous
tail slides till the nose falls back over. Rolls are
crisp but it takes some practice not to over rotate on high
rates especially at higher speeds. Point rolls look
great and the DS821 digital servos have excellent holding
power on this size plane.
biplanes knife edge pretty well because of the added side
area of the interplane struts and the Christen Eagle is
no exception. It does pull slightly to the gear as
well as exhibiting some roll coupling but with a little
elevator mix it and a touch of aileron stick knife edge
in either direction looks good. Spins were tight but
with the CG where we had it, the Eagle just wouldn't
flatten out but tumbles and pop tops looked spectacular.
Spins stop when you neutralize the controls whether upright
or inverted. The Byron Rotor Rage heli fuel made it appear
as if we were running smoke and my favorite move with the
Eagle was getting it to tumble into a cloud of its own smoke.
Christen Eagle will stall if you get it slow enough, and
when it does it will drop a wing. Pushing the nose
down and adding power will have you quickly flying again.
With this in mind, and the drag created by the large cowl
and dual wings, landings should be made with some power
and flown to the ground. Don't chop power until
you're "over the numbers". The Eagle
will settle into a nice 3 point landing once the engine
is broken in and a reliable idle established.
9 did a great job with the Christen Eagle II. The airframe
is well built and the ARF goes together with very little in
the way of problems. About the only real negative I
found in the kit were the very thin plastic landing gear fairings.
After breaking on the initial flight they never got any worse
through about 20 flights we put on it but everyone that looks
at the plane feels obliged to point them out. Securing
the pilot figure should be done before flying it but two servos
screws and about 30 seconds is all that it takes.
The flight characteristics are simply outstanding. Several
pilots in my club got a chance to fly the Eagle. Christen
Eagle veteran Brian Wiltse said it flew every bit as good
as his (dearly departed) larger Christen Eagle. Two
outstanding pilots, Mike Hunter from my local club in Jacksonville,
and Neal Kaploric from Deltona, Florida took turns putting
the Eagle through its paces and both really enjoyed the aircraft.
The Saito 125 is a very nice engine and its higher power output
and lighter weight make it a very good match for the Eagle.
Having seen the electric version fly I would have no hesitation
about building this plane electric either and Hangar 9 thoughtfully
gives you the choice.
Hangar 9 Models
Distributed through Horizon Hobby
Champaign, IL 61822
Phone: (217) 352-1913 http://www.hangar-9.com/
JR and Spektrum Radios
Distributed through Horizon Hobby
Champaign, IL 61822
Phone: (217) 352-1913 http://www.spektrumrc.com/
ZAP and Pacer Adhesives Distributed by Frank Tiano Ent.
3607 Ventura Drive E.
Lakeland, Florida 33811
Phone 863-607-6611 http://www.franktiano.com/
The comments, observations and conclusions made in this review are solely with respect to the particular item the editor reviewed and may not apply generally to similar products by the manufacturer. We cannot be responsible for any manufacturer defects in workmanship or other deficiencies in products like the one featured in the review.