I saw the Cox Christen Eagle at the WRAM show and was mightily impressed.
I spoke with the Cox rep about the Eagle and the more we spoke,the more I liked it as a third or fourth plane on which to learn ailerons and some aerobatics at a reasonable price. He kindly offered to send one to try out.
Motor Thrust: 17 ounces; Eagle Thrust/Weight Ratio: 0.77
Motor Max Sustained Load: 18 Amps; No load kv: 1100 rpm/v
Included Prop: 10 x 4.7 SF
Motor Dimensions: 40 × 48 mm, Shaft Dimension 4 mm, Weight 52.4 grams
ESC: Sensorless with BEC; rated for 18 amps continuous; hardwired settings
LiPo: 1800 mah 3S1P, rated 10C continuous
The Eagle arrived in one of the best packed boxes I have seen – all parts were bubble wrapped and the foam container was neatly compartmented to protect parts:
Unpacked, the Cox Eagle has only a few parts to it – assembly is basically add the servos and transmitter, adjust the servo travel, then bolt on the wings – the Eagle should be ready to fly with one evening's work.
These are the parts included with the Eagle (also inluded are servo arms which do not fit Spektrum S75s):
Nice to have another metric wrench! Note that the battery does not have a balancing plug – I spoke to Cox about this and they stated the stock of batteries was ordered 24 months ago when balancing was just becoming main-stream. However, a balancing plug can be added but does require soldering.
{mospagebreak}
The Cox Eagle's Parts – A Closer View
The ESC has a nice heatsink; note that in the nose of the plane, there are four sharp screws which hold the cabane struts
to the body which are held in place by plastic retainers glued to the foam body. Mounting the ESC away from these exposed screws is a prudent step. Included with the ESC is a two prong plug:
According to Cox:
"The 2 prong plug is for switching the ESC to a 2-cell cut-off. A shorting strap is attached to the prongs. This is the only programmable feature of the ESC. [If the prongs are inadvertently shorted] the only danger would be if there is a constant short, the wrong cut-off is applied." I taped the two prongs over to avoid any problem.
The cabane has two nuts glued to the plastic frame – the top wings bolts to the cabane with two nylon screws.
There are two battery compartments – one for NiMh (not used) and one for the included Lipo:
The battery ships with a Deans-like plug – it's NOT a Deans:
A close look at the male plug shows that it is not as nicely finished:
I found the battery plug an incredibly tight fit – so much so that I filed the tangs down a bit to loosen it up.
The Outrunner is bolted onto a rigid plastic bulkhead:
A back view shows the windings and PCB:
The landing gear includes wheel pants that look very nice:
Unfortunately, I land on grass and I replaced the very spiffy wheel pants with a larger wheel:
Finally there is a steerable, small tail wheel:
Overall, build quality looks good. Some of the decals, however, had bubbles in them – the instructions state that spraying the decals with a clear lacquer will protect them – they are somewhat fragile and will lift off if your fingers are sticky.
{mospagebreak}
Assembly Notes
The Cox Eagle is about as close to RTF as an ARF can be. This should not take more than 3 hours to assemble, once you have the servos and receiver in hand. I found the control surfaces a bit stiff – I would suggest working them before installing servos to loosen them up a bit. I also found that the elevator rod was binding in its exit slot:
A few strokes with an X-acto and it was free. The bottom wing includes a servo pocket for the ailerons – I used Spektrum S75s and it was a VERY snug fit – no way this is coming out (a touch of glue for safety).
I did find that the aileron's control arms did not clear the body when mounting the bottom wing:
I had to cut two small grooves so that they could clear – no big deal. The rudder and elevator servos, however, were not snug at all, especially after doing some cutting for the servo wires to clear the pocket. I epoxied two 1/8" plywood strips to the foam and securely screwed the servos (pre-drilled holes) down.
There is plenty of room for any receiver – I used an AR-6000, mounted with velcro:
The top ailerons are actuated by a rod connected to the bottom ailerons – the connection point is a small control horn bolted to the top wing:
THESE ARE DELICATE! While adjusting the clevis on the rod, even though I held the rod in place with a pliers, I managed to snap one off. You can see that there are two holes aft of the forward hole – these weaken the arms. I managed to fix the broken arm by first epoxying it together, then I applied a small strip of Sig Koverall saturated with epoxy to strengthen it. As a preventive measure, I filled the two small holes on each arm with epoxy to strengthen them.
All finished with my large wheels:
The landing gear slips into a slot between the two battery compartments – the manual suggest gluing it in. The gear is made up of wire and will bend on any hard landing. The canopy is held on by four small sticky tabs – IMHO not enough. Either add some more sticky tabs or use a rubber band to hold it in place (the quick-and-dirty fix).
{mospagebreak}
Initial Flight Impressions
Flying time has been limited lately due to windy days and snow on the ground. I was able to get in a short flight in (about 8 minutes – the field was more swamp than grass due to emlting snow):
As I expected, the symmetrical wing requires more speed than, say, a flat bottom or undercamber wing;
Slow speed performance is OK but the margin for error narrows quickly;
Performance is "spirited" and controls are sensitive; a heavy hand on the stick is not recommended;
Exponential rates are highly recommended – I used +30;
I hand launched without a problem – the climb out was straight and up;
I started with the control surfaces flat and needed a few tics of down elevator to keep it from porpoising at wot.
Overall, the stock motor is OK but I found (initial impressions) that it requires about 75% throttle at level flight to keep things going nicely; at something like 40-50% throttle, it descended quickly.
IMHO this is a super buy for the flier who is interested in learning aerobatics – it's not super-duper sensitive, but will do the basics quite well. Re-fitting the stock outrunner with one to give a thrust/weight ratio around 1.25 should ratchet performance up very smartly. Finally, it's very sharp looking.
At an MSRP of $130, this is a good buy.
Selected User Comments
I asked for some user comments among current Eagle owners and also looked around in some forums for additional comments – excerpts below:
Thomas B
"I really only saw two things I did not like on first inspection.
The tie wraps that secure the front of the interplane strut on the top wing looked a little crude to me. With as many other nice injection molded parts that they supply in the kit, it would have been nice to have a neat little molded "shoe" installed in the bottom of the top wing that the front of the strut could snap in to. Also, the aileron torque rods being exposed on top of the ailerons was a little ugly."
Manish
"I am very happy with the Stock motor. Good power along with flight times equals a nicely balanced power system. The motor is not a 3D powerhouse motor, but then again I like to fly the Eagle like the full size version flying in an airshow. It will do any of the aerobatic maneuvers with style. I experimented with a 1320 TP pack which pushed the cg back just that little bit and was able to perform inverted flat spins. Very cool. The Eagle flat spins like a leaf falling from a tree. Just floats down."
Red61
"Stock motor, stock battery, APC 9×4.7 prop:
5490 RPM
90.3 Watts, peak; 8.31 Amps, peak
10.73 Volts, minimum
24.43 MPH (top prop pitch speed)
13.00 minutes of flight (at full throttle)"
Frank
"I hooked it up to my "watts up" meter, and at full throttle it was using 11-12 amps and about 128 watts indicated., half throttle position showed about 4-5 amps. RPM was around 6600 with the supplied prop.
Weight ready to fly was 22 oz exactly.
Took it out this morning, and it handled very well on the ground, tracked pretty straight, and lifted off when I was only at about 1/2 throttle, I climbed to altitude, needed lots of down elevator trim, and a lot of right aileron. Once trimmed it was pretty neutral for different power settings.
I did most normal aerobatics, rolls (good roll rate on high rates, reasonable on low), nice tight loops, outside loops without falling out, good snaps, knife edge wanted to go away from the canopy, and needed some speed to keep the nose up, immelmans, and cuban eights were all done on settings near half throttle.
It will almost hover, but has plenty of power for most normal aerobatics and low throttle settings. It landed extremely slowly with a bit of power on, flared nicely as I pulled power off. A very relaxing plane to fly, with just a few minor issues."
If interested, do a search on the RC forums for "Cox Eagle" for additional comments.
Cox Christen Eagle
I saw the Cox Christen Eagle at the WRAM show and was mightily impressed.
I spoke with the Cox rep about the Eagle and the more we spoke,the more I liked it as a third or fourth plane on which to learn ailerons and some aerobatics at a reasonable price. He kindly offered to send one to try out.
Key Specs:
The Eagle arrived in one of the best packed boxes I have seen – all parts were bubble wrapped and the foam container was neatly compartmented to protect parts:
Unpacked, the Cox Eagle has only a few parts to it – assembly is basically add the servos and transmitter, adjust the servo travel, then bolt on the wings – the Eagle should be ready to fly with one evening's work.
These are the parts included with the Eagle (also inluded are servo arms which do not fit Spektrum S75s):
Nice to have another metric wrench! Note that the battery does not have a balancing plug – I spoke to Cox about this and they stated the stock of batteries was ordered 24 months ago when balancing was just becoming main-stream. However, a balancing plug can be added but does require soldering.
{mospagebreak}
The ESC has a nice heatsink; note that in the nose of the plane, there are four sharp screws which hold the cabane struts
to the body which are held in place by plastic retainers glued to the foam body. Mounting the ESC away from these exposed screws is a prudent step. Included with the ESC is a two prong plug:
According to Cox:
"The 2 prong plug is for switching the ESC to a 2-cell cut-off. A shorting strap is attached to the prongs. This is the only programmable feature of the ESC. [If the prongs are inadvertently shorted] the only danger would be if there is a constant short, the wrong cut-off is applied." I taped the two prongs over to avoid any problem.
The cabane has two nuts glued to the plastic frame – the top wings bolts to the cabane with two nylon screws.
There are two battery compartments – one for NiMh (not used) and one for the included Lipo:
The battery ships with a Deans-like plug – it's NOT a Deans:
A close look at the male plug shows that it is not as nicely finished:
I found the battery plug an incredibly tight fit – so much so that I filed the tangs down a bit to loosen it up.
The Outrunner is bolted onto a rigid plastic bulkhead:
A back view shows the windings and PCB:
The landing gear includes wheel pants that look very nice:
Unfortunately, I land on grass and I replaced the very spiffy wheel pants with a larger wheel:
Finally there is a steerable, small tail wheel:
Overall, build quality looks good. Some of the decals, however, had bubbles in them – the instructions state that spraying the decals with a clear lacquer will protect them – they are somewhat fragile and will lift off if your fingers are sticky.
{mospagebreak}
The Cox Eagle is about as close to RTF as an ARF can be. This should not take more than 3 hours to assemble, once you have the servos and receiver in hand. I found the control surfaces a bit stiff – I would suggest working them before installing servos to loosen them up a bit. I also found that the elevator rod was binding in its exit slot:
A few strokes with an X-acto and it was free. The bottom wing includes a servo pocket for the ailerons – I used Spektrum S75s and it was a VERY snug fit – no way this is coming out (a touch of glue for safety).
I did find that the aileron's control arms did not clear the body when mounting the bottom wing:
I had to cut two small grooves so that they could clear – no big deal. The rudder and elevator servos, however, were not snug at all, especially after doing some cutting for the servo wires to clear the pocket. I epoxied two 1/8" plywood strips to the foam and securely screwed the servos (pre-drilled holes) down.
There is plenty of room for any receiver – I used an AR-6000, mounted with velcro:
The top ailerons are actuated by a rod connected to the bottom ailerons – the connection point is a small control horn bolted to the top wing:
THESE ARE DELICATE! While adjusting the clevis on the rod, even though I held the rod in place with a pliers, I managed to snap one off. You can see that there are two holes aft of the forward hole – these weaken the arms. I managed to fix the broken arm by first epoxying it together, then I applied a small strip of Sig Koverall saturated with epoxy to strengthen it. As a preventive measure, I filled the two small holes on each arm with epoxy to strengthen them.
All finished with my large wheels:
The landing gear slips into a slot between the two battery compartments – the manual suggest gluing it in. The gear is made up of wire and will bend on any hard landing. The canopy is held on by four small sticky tabs – IMHO not enough. Either add some more sticky tabs or use a rubber band to hold it in place (the quick-and-dirty fix).
{mospagebreak}
Flying time has been limited lately due to windy days and snow on the ground. I was able to get in a short flight in (about 8 minutes – the field was more swamp than grass due to emlting snow):
Overall, the stock motor is OK but I found (initial impressions) that it requires about 75% throttle at level flight to keep things going nicely; at something like 40-50% throttle, it descended quickly.
IMHO this is a super buy for the flier who is interested in learning aerobatics – it's not super-duper sensitive, but will do the basics quite well. Re-fitting the stock outrunner with one to give a thrust/weight ratio around 1.25 should ratchet performance up very smartly. Finally, it's very sharp looking.
At an MSRP of $130, this is a good buy.
I asked for some user comments among current Eagle owners and also looked around in some forums for additional comments – excerpts below:
Thomas B
"I really only saw two things I did not like on first inspection.
The tie wraps that secure the front of the interplane strut on the top wing looked a little crude to me. With as many other nice injection molded parts that they supply in the kit, it would have been nice to have a neat little molded "shoe" installed in the bottom of the top wing that the front of the strut could snap in to. Also, the aileron torque rods being exposed on top of the ailerons was a little ugly."
Manish
"I am very happy with the Stock motor. Good power along with flight times equals a nicely balanced power system. The motor is not a 3D powerhouse motor, but then again I like to fly the Eagle like the full size version flying in an airshow. It will do any of the aerobatic maneuvers with style. I experimented with a 1320 TP pack which pushed the cg back just that little bit and was able to perform inverted flat spins. Very cool. The Eagle flat spins like a leaf falling from a tree. Just floats down."
Red61
"Stock motor, stock battery, APC 9×4.7 prop:
Frank
"I hooked it up to my "watts up" meter, and at full throttle it was using 11-12 amps and about 128 watts indicated., half throttle position showed about 4-5 amps. RPM was around 6600 with the supplied prop.
Weight ready to fly was 22 oz exactly.
Took it out this morning, and it handled very well on the ground, tracked pretty straight, and lifted off when I was only at about 1/2 throttle, I climbed to altitude, needed lots of down elevator trim, and a lot of right aileron. Once trimmed it was pretty neutral for different power settings.
I did most normal aerobatics, rolls (good roll rate on high rates, reasonable on low), nice tight loops, outside loops without falling out, good snaps, knife edge wanted to go away from the canopy, and needed some speed to keep the nose up, immelmans, and cuban eights were all done on settings near half throttle.
It will almost hover, but has plenty of power for most normal aerobatics and low throttle settings. It landed extremely slowly with a bit of power on, flared nicely as I pulled power off. A very relaxing plane to fly, with just a few minor issues."
If interested, do a search on the RC forums for "Cox Eagle" for additional comments.