|Wing Area:||13.95 dm2|
|Wing Loading:||8.5-9.6 oz/sq ft.|
|Battery:||7x730AAA nimh (recommended), 3s1p Apogee LiPo 1500ma|
|Motors:||2 GWS EDF55 fan w/S300 brushed motors|
Most of us who know anything about aircraft are familiar with the Fairchild A-10 Thunderbolt II, also known as the Warthog. This highly maneuverable ground attack sub-sonic aircraft with a 30mm rotary canon has been in service since 1973. It was actually being phased out in the late 80’s when a need arose for it again. It can withstand major damage and still fly and even has a titanium “tub” around the pilot for protection. The A-10 has brought more than one pilot home that would not have otherwise made it in any other aircraft. It was even designed to land with the wheels retracted without sustaining major damage!
The A-10’s layout is great for model aircraft with its twin turbofans on pylons above the fuselage, meaning no ducting to mess with. The bottom and sides of the fuselage are flat with tricycle landing gear for good ground handling. The large wing is not swept back and has a thick reflex airfoil incorporating anti-vortex turned down wing tips.
I was lucky enough to get a pre-production GWS A-10 at the International Modelers Show from Mr. Lin. The A-10 was molded in white foam like all GWS Parkflyers. It was designed to use 4 channels, using the 4th channel for nose wheel steering instead of the normal rudder. It included two GWS EDF-50 (50 being the diameter of the impeller in mm) units with IPS brushed motors. These EDF units seemed a little small and some early flight reports were that it was a little under powered with them. Some replaced the stock 3 blade impeller with 5 blade units and some went up to 8 cells. But the IPS motor and fan could only do so much and the A-10 was not really happy either way. I have flown a couple of them with the EDF-50’s and performance was just adequate. Many have been “moded out” with better fans and even brushless motors. With this in the back of my mind I waited until the newer one was available with the EDF-55 units powered with S300 motors. I snagged one of these when they came out and based this review on that. You can also upgrade the EDF-50’s to the 55’s with new nacelle kits as well.
The A-10 is packaged well and the wing is taped to a piece of cardboard to protect the tips, which is good because many of them came broken in the earlier kits. The instruction book is in color and easy to follow, but needs some work on the English translations. My kit’s instructions included 2 amendment sheets. One stated not to exceed 8.4 volts on the motors and the other on how to convert it into a pusher with S300’s. In the back of the book it had pictures of 3 different color schemes including desert, jungle and gray. It also included the decals for each version.
My new A-10 came in gray, which is what most real A-10’s are painted now. It is designed for 4 channels (ailerons, elevator, throttle and nose steering) but can be built for 3 channels with ease. I chose to build my A-10 with the gear permanently retracted for a cleaner look in the air. Now this would normally mean only hand launching for most planes, but not with the A-10. With its landing gear retracted the main wheels still protrude from their faring more than enough to be functional. And since they retract forward, the wheels end up ahead of the leading edge, effectively making the A-10 a tail-dragger. This actually works well and solves 2 issues. One is the tail skid can now protect the lower vertical fins, which hang down below the fuselage. And by adding rudders ROG’s and steering are still possible so I can hopefully avoid items that get in front of me when I land and takeoff!
For the aircraft radio gear, I used the RC Mart electronics from my Shogun helicopter that I had upgraded. It looks like it is the same as Cirrus gear. The 6 channel single conversion RX, 20 amp ESC and 2 of the micro servos would be just right for the A10. I used a Hitec HS-55 servo for the rudder/tailwheel to keep the weight down. For the transmitter I used my new Multiplex Evo 12. This is one nice transmitter for those interested, so look for the review coming soon from Andy Willetts.
The EDF-55’s come pre wired to a BEC connector (sometimes called a JST). I broke in both EDF units with a couple of D cells using the stock wiring harness. Breaking in can motors like the S300’s can really improve the performance and life of the motor. After break-in I tested the EDF-55’s with 7 cells and a C-clamp type watt-meter. The motors drew 11 amps wired in parallel. From experience and discussions I knew this was about double what the recommended AAA batteries, BEC connectors and stock wire could handle. The stock BEC connectors and wire are fine for about 5-6 amps. So the EDF units and Y harness would be fine down to where they are paralleled, but needed some help to the ESC. So I simply snipped off the wire at the Y and made a new harness with some 18-gauge silicon wire and Deans 4 pin connectors. This fixed both the limitations of the BEC connectors and the wire size concerns. Plus the RC Mart ESC I used was already fitted with the Deans 4 pin micro plug.
Building the fuselage was simple since there were just 2 pieces. Since I was building mine with the gear retracted, I omitted the steerable nose wheel. If you use the nose gear it must be assembled before you glue the fuselage halves together! Be sure to check the fit first as there were molding bumps in mine that had to be removed for a good fit.
I then mounted the assembled EDF units to their pylons. There are slots on the nacelles to keep it all lined up. The EDF units looked like a lot of weight for the foam pylons, so I added some .125 Carbon Fiber tube between the nacelles. I used a piece of 1/8 inch brass tubing as a drill and epoxied the CF tube in. If you have not used a piece of tubing for a drill before, just use a counter sink on an end to sharpen the edge and it will cut through the foam with no problem. I used more painters tape to hold the nacelles on as the epoxy set.
Having seen the wing in some other A-10’s flex quite a bit, I wanted to add a little more strength, so I substituted a piece of .125 carbon fiber tube for the bamboo main spar. I inserted this spar in from the outside of the wheel fairing which gave the maximum support.
I wanted to keep the main wheels looking close to scale, but still have some “give” for those not so perfect landings. So I devised a way to mount the wheels in the correct location forward of the wing leading edge, but not have that location take the full landing loads. With this in mind I used Du-Bro 1.5 inch foam micro wheels mounted on a piece of .032 wire. The wire is bent in a U to run parallel to the wheel and is attached at the stock GWS location. The assembly lays flat against the faring and keeps the scale look intact. A small piece of bamboo embedded in the fairing is used to keep the wire from digging into the foam just behind the cutout for the wheel. This bamboo was left over from my kit since I used the carbon fiber tube for the wing spar.
For rudder movement I used a trick I saw in a hand-launch glider using a torsion rod. A piece of wire is used and one end is fixed to the solid surface with a slight bend in it that pushes the movable surface in one direction. You then use a “pull” thread on the opposite side attached to the servo to center the surface. I setup each rudder to pull out with the pull string centering them. With this setup the opposing rudders balance out each other and the servo works no harder than normal. It seems to work very well so far.
The Azarr M-72 micro antenna was already on the RX so I drilled a little hole up into the cockpit area and inserted it there. The only other spot would have been straight up or between the EDF units. The RC mart servos are a little noisy but seem to work and center well. They look like many of the other generic 9 gram servos that are popping up all over the place. I attached the elevator servo with double sided tape.
I mounted the ESC a little closer to the RX than I like, but it had to go somewhere.
With the building done, I found it needed about ¾ ounce up front to get the CG close. Placement of the equipment would have made little difference I think. Of course not using the steerable nose gear and fabricating the rudder setup may have impacted This was with both the stock and 3 cell Apogee pack.
Now I just had to wait a few weeks for nice weather for flying weather. And I waited and waited. Yes, I even live in California.
With a few adjustments at the field it was finally ready for the first flights. With a fresh 7 cells GWS pack it was fired up and my flying buddy Bob gave the A-10 a little push. It settled into the ground after 3 tries. The 7 cell AAA pack was just not going to cut it. So I broke out the 3 cell Apogee 1500 Lithium. With the voltage of 10 cells now the fans really sounded much better. The next launch went great but I had way too much elevator and not enough aileron. So a quick adjustment on both surfaces the next flight went great. It was fast but the roll rate was still slow with as much aileron as I could dial in. The elevator was touchy even with expo and I attribute this to the short movement. Power was now more than ample and it was solid in the sky. Landing was a joy but the flying site did not allow anything but hand launches and belly flops into the tall grass.
Flight pictures and video were of such low quality I have nothing to share yet,,,,,,,,stop back soon for more!!!
I found the A-10 to be for the advanced pilot; this is what GWS recommends also. It flies very nice and launches easy. The few I have seen ROG do so quite well with the stock wheel setup, but please use other wheels! Retracts would be a plus and add some nice bling. A radio with expo should be used at least but most advanced pilots will have this in their stable already. It looks and sounds like the real thing in the air but is still small enough to handle if you have a lot of other planes.
3rd generation to come
I am about to set up another upgrade of the previous versions.
Powered by brushless CDR engines 20x10 enabling roughly 130W each,
powered by 3s SHD LiPolys.
On the maneuver side i am going to invest in 2 more powerful aileron/flaperon servos, taking the standard aileron + inner flap lenght into use.
This hopefully will soften my landings without retracts so far.
On the coating side i am going to use the new generation of acrylic water-thinned spray paints (1/10 thickness of conventional car paints) and
plenty of super-light filler to fill in the raw concrete type of surface and the unbelievably deep canyons between the skinplates of the original (sorry GWS guys!!!).
I tend to get some 7N of thrust hoping to keep the AUW around 500-600g,
so help me the RC society!!
I'll come back with results,
jnivari; Hi, I have followed you article with interest. Any thoughts on retracts yet?
I am using your setup with a GW/A10-EDF55-300H ,dual GS-B2030/10'S and Tp Li-Poly 2100mAh/7.4V. I haven't decided whether 1 or 2 ESc's should be used yet. The LHS is checking it out.
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