|Wing Area:||288sq” 18.8dm2|
|Wing type:||Flat bottom|
|AUW weight:||25.2oz 705g|
|Wing loading:||12.6 oz/sq. ft.|
|Servos:||6 – Micro size|
|Receiver:||Hitec Electron 6|
|Battery:||Dualsky 1700 mAh 12C 3s|
|Motor:||xMotor 400B (950 Kv)|
|ESC:||Velocity 18 amp|
Well I hear many of you on the forums talk about how we do not review many kits anymore. I fear this is a bit of a sign of how busy we are and how the quality and short assembly times of the current ARF’s get us in the air so quickly. With that said I am a long time modeler and I truly enjoy the building aspect of the hobby.
With today’s laser cut kits assembly is also very quick, a fact that may have eluded some current modelers. So this review will be a kit building and flying. One great advantage of kits is the manufactures frequently offer projects of rarely modeled planes. This is the case with E*STAR models. Do not be afraid to take on your first kit!
E*STAR Models is indeed one of those using laser cutters that make our assembly easy and fast. They offer a number of amazing models, the one that caught my eye is the Air Tractor 802. A close second is their new Feiseller Fi-156 Storch. Check out all their offerings at their website: E*STAR Models
Many of us seek unique full scale ships for our scale model builds, and I have a long time love of crop dusters. Although primarily used for crop dusting, the Air Tractor 802”F” model is used for firefighting! Yes this single engine plane has an amazing 800 gallon capacity and is used to drop water or fire retardant chemicals as a front line fire fighter!
From the Air Tractor site: “Reflecting state-of-the-art technology in computerized fire gate controls, the AT 802F is an ideal initial attack fire fighter with the ability to get to fires quickly and the maneuverability to put them out accurately and efficiently. The reliability of the turbine engine, low maintenance and operating costs, ruggedness and safety features make it an excellent choice for fire fighting.”
The shipment from Korea was quick, although when the box arrived it was clear that it had a very rough ride. Upon opening the contents were well packaged in bubble wrap and although the box was damaged none of the kit contents or parts showed any damage.
I was immediately impressed by the look and quality of the balsa and especially the laser cutting. There was no sign of laser charring – even on the thickest balsa parts. Very impressive and no question they have great control on their cutting system.
Balsa quality was also very good. Some of the parts are from fairly thick stock, so it was good to see light balsa being used.
This kit has many laser cut parts that went together very quickly and with a minimal fuss. Most builders should allow for about 14-18 hours for a fully framed, sanded and ready to cover plane.
Following the instructions, I began with the rudder, elevator and stabilizers. The parts were laser cut and fit well. The parts keyed together making it very easy to assemble. Assembly was done over the plans as recommended to keep everything straight square and true.
The wing is a typical D-Tube construction using two balsa spars, sheeting and rib caps.
The sheeting was all laser cut (NICE!), and it fit perfectly. Wing cutouts for servos were pre-cut and in place. Plywood was supplied for the root rib, as it supported the ply spar doublers -- the design needed that additional strength. Also included were two flat ply attachment plates for securing the wings to the fuselage.
Ribs are cut from curiously thick 3/16” stock. They do have lightening holes but thinner stock would be more than sufficient, especially considering the ribs all have cap strips installed.
With two aileron servos and two separate flap servos you will need some “Y” connections or a 7 channel computer radio system with a 7channel receiver and software mixing. I used two short 3" Y connections for both aileron and flaps.
An odd omission is the fact there is no included battery tray. Thankfully it is a simple task to create one yourself. I simply used 1/8" light-ply tray glued directly to the outer portions of the spar box and former.
The fuselage assembly is very unconventional and interesting! That does not mean it was difficult, but any builder will need to refer to the plans and instructions regularly. The fuselage starts with three stringers, two of which go from the firewall to the tail. Follow steps carefully as the parts key together, and they must be done in proper order.
Some Key Points:
The cowl is made from the same vacuum formed clear plastic the canopy was. A small amount of trimming will have it fitting to the nose of the fuse very well. It attaches with four included screws into ply and balsa mounts glued to the firewall. It is necessary to trim the hole in the front for the motor shaft and cooling.
As noted the kit contents are masterfully cut from good stock, but there was plenty of plywood and rather thick balsa. I was a bit concerned about the final all up weight of this plane. Plans specify a 25-26oz all up weight (AUW)....as you can see, mine is at the low end of the AUW...GREAT!
|Wing panels (with servos)||157g total|
|Pilot and Chairs (not included)||11.2g|
|Radio components/Motor ESC||172g|
|Total assembled kit weight||582g (20.8oz)|
|Total AUW||705g (25.2oz)|
The wing loading remains a park flyer light at 12.6/sq ft. That allows it to slow nicely for landings – especially with large flaps deployed. Guess I needn't have worried about the wood selection!
XMotor 400B Motor
My thoughts on the motor: The motor ran perfectly out of the box. I wanted a low Kv so it would handle the 9x7x3 propeller without raising the amp draw too high. I can say that this motor is a perfect combination for the this 25oz scale ship.
The motor mount is the common 10mm square stick type. As I will be using the xMotor 400B out runner type motor I needed to fabricate a mount system.
Thankfully that fabrication is made easy with the out runner mount by Horizon Hobbies. It allows use of the typical stick type mount. Notable is the mount puts the motor shaft in the same position as it would have been using the standard GWS gearbox unit. Very slick and no modifications needed! Check it out: E-Flite Out runner mount
Down and right thrust is set by the formers and gives about 3 degrees of both down and right thrust. This was perfect for keeping throttle pitch trim changes in check.
For covering I used Nelson Solite material. It is strong and light. I know from past usage that the white color shows the underlying balsa as it is not perfectly opaque, so I tried a trick. I actually did a very light coat of white paint directly to the balsa prior to covering. This was an excellent idea that I read about on the forums here. It helped the lack of opacity of the Solite covering.
Considering the full scale plane has a turbine engine, I wanted to select a power system that would swing a scale size 3 blade propeller. That would require a motor with a bit lower kV rating in order to swing a 9 inch three bladed prop.
This XPower motor has been around for a while now. They are very high quality and I have been impressed by their looks and performance. The fit and finish was very good, bearings were smooth. Cogging was comparable to most of my out-runners. Performance was excellent as can be seen. Check them out here: 2DogRC
The motor produced the following results using the following propellers:
|GWS HD 9x7.5||13.9||154|
I started flight testing with the APC-sf 9x4.7 propeller. Even with the low pitch speed, the plane flew well. The three bladed propeller looks best but with the 17+ amp draw I was concerned about the motor. I also did not have a 1.5" 3-blade cutout spinner. I may still try this propeller in the future, contacting ParkFlyer plastics to have a 1.5" spinner vacuum formed just for this plane.
As can be seen, this motor is strong and it provides significant motivation for this scale airplane. I highly recommend it.
Dimension Engineering Park BEC and ServoSense Plus
My thoughts on these products: The ParkBEC and ServoSense Plus performed wonderfully. No more worries about overamping your ESC BEC and now you know exactly what your servo in flight amp draws are. No more guessing about in flight amp draws. This gives great peace of mind.
*From the DimensionEngineering web site: “With the linear BEC built into most speed controls, the current rating decreases as pack voltage increases. For example, several popular 25A ESCs with "3A" BECs are only capable of supplying 0.5A when running from a 3s pack. Because it is an efficient switching regulator, ParkBEC can supply its full rated current of 1.25A all the way up to 8s.”
With the Park ServoSense Plus I was able to measure actual in flight amp draw of the entire airborne radio system. I checked the flight you see featured in the video. In flight my 6 servos plus the Electron 6 RX drew an average of 100mA during the 8 minute flight. The Park ServoSense Plus also shows the max amp draw of 400mA and the maximum draw during any 15 second period of 400mA.
I was amazed at the low amp draws here, so I did a test on the ground. I ran all the servos from one max throw to the other for over one minute. I recorded a maximum 700mA draw with an average amp draw of 200mA and the maximum for any 15 second period of 400mA. It was clear the 1.5amp Switching BEC would handle 6 servos with ease.
This Park ServoSense Plus is a fantastic tool that enables us to know how hard we are pushing our BEC circuits. We all need one of these in our flight box. Highly recommended. Dimension Engineering
For this project I used an 18 amp Velocity ESC from 2DogRC. I have used a couple of these now with great results. As an added bonus you can use the Jeti controller programming card with these ESC's as well.
Dualsky Xpower LiPoly 1700 mAh 12c packs
My thoughts on this pack: The pack performs very well. As you can see from the AMP draw tests it holds voltage very well in the 14 AMP draw testing.
For this project I used a Dualsky Xpower 1700 mAh LiPoly 3s battery pack. It easily provided the 14-15 amp draws this motor demands. I have used the Dualsky packs in the past and been very happy with them and this one is no exception. Recommended.
The battery performed very well with no issues encountered. The capacity allows for 12-15 minute flights, long enough for me. Dualsky has just released some new 20c cells as well so be sure to check them out also.
The recommended CG is right on top of the forward spar. This CG setting is a good starting point making the plane stable yet it did not sacrifice responsiveness. The battery area is large and it will accommodate heaver power systems by moving the battery toward the servo tray. With the light xMotor 400B the pack was placed forward in the compartment.
I used my Airtronics RD8000 radio for this plane. Rates were set as recommended in the manual. Ailerons are at 16mm, rudder at 19mm and elevator at 16mm. No high rates were mentioned so I set those at about 20% more throw. Flaps are set using the two recommended settings -- 20 and 45 degrees.
I set exponential at 25% on both ailerons and elevator and this proved to be too much. For my flying style, I found the ailerons did not need any exponential and I changed the elevator to 10%. The flight timer was set to count down from 8 minutes, although the 1700mAh battery will be good for 12-15 minutes.
I always snap some pictures before first flight. Here are a few of my firefighting version of the AT802F.
With the high aspect ratio wing the first flight was as expected, very easy and sedate. This plane in fact can easily be added to the "first low wing trainer" type line-up.
It required only elevator trim changes and those were due to missing setting neutral on the elevator on my part. On first flights I make all attempts to check the basics, trim the airplane and check stall.
Takeoff is very short only requiring a few feet. This takeoff was without the use of flaps. The Air Tractor lifted off with a slight touch of up at full power. It only required a touch of right rudder correction to keep it straight down the center line. With the 9x4.7 propeller it has a scale climb rate. More pitch would make that even more aggressive.
This plane stalls predictably with a slight nose drop. It does not tend to drop a wing tip at all, just a nice gentle nose drop. It is controllable right down to the last second. The plane recovers very quickly once power is added.
The landing was very easy -- I just controlled with throttle allowing for the correct sink rate. I kept power on -- this large wing, fuselage and canopy all produced a great deal of drag. Again the first landing was done with no flaps. The rudder is effective and the plane slows down very well.
Second flights mean running the plane through more tests. This is where we explore more of the flight envelope.
The AT802 loops well from level flight. It is easy to keep the loop round and large.
The large aspect ratio wing and barn door type ailerons yield slow graceful rolls. I needed to apply "down" elevator in the inverted portion of the roll to keep the nose from dropping. None of these factors is surprising considering the long wing span. I added 20% more throw to the ailerons to speed the rolls and add responsiveness.
Spins are very slow and predictable. The plane will recover very quickly once the controls are released and power is applied.
This plane reminds me of a Cub when doing hammerheads. The rudder is effective and kicks the short tail moment over nicely. The will be a trademark maneuver for this plane.
Inverted flight is possible, but it requires almost full down to keep the plane in level flight. This is likely an indication not only of the flat bottom airfoil but that the CG can be placed more rearward.
Thanks to the large flaps, this plane reacts to flaps like no other model airplane I have ever had. They produced significant drag and lift, and I was pleasantly surprised by the lack of pitch change. I have never flown a plane with as little pitch change with the 20 degree setting and only a slight amount with the 45 degree setting - amazing!
With 20 degree flaps takeoff distance cuts in half. Landings also slow to a walk when using the 20 degree flap setting. At 45 degree and a 7-8mph wind I swear I nearly landed backwards - this is not an exaggeration. Control of aileron, pitch and yaw remain good even with the flaps deployed fully.
It was a blast to play with flaps on this plane. The flaps are highly recommended for great flying fun.
This ship has very "scale" sized tail surfaces and throws so it really does not lend itself to 3-D flight. It is intended to be flown "on the wing".
I settled on the 9x4.7 APC-sf propeller for the first test flights. The 9x4.7 propeller did keep the top end speed down, but provided excellent thrust. Flights were also done with the GWS-HD 9x7.5 propeller. This propeller provides better top end speed and allowed the use of 60-70% throttle settings. It consumes only about an amp more power at full throttle. The full scale variant has a 5 blade propeller, needing that to suck up the nearly 1500hp the turbine produces!
Any power system with the recommended 120-150 watts will give excellent results. I have flown the plane with both 120w and 150w. I like the 150w system better, but was rarely at full throttle. With the higher power the plane has plenty of reserve power always a plus. The 2DogRc xMotor is an excellent choice.
While not a first time trainer the AT802 would make a good first low wing plane. It was surprisingly calm and sedate -- it seemed much like a Cub, only low wing. It should be noted that the AT802 is not self correcting, something that any first time flyer needs.
Editor's Note: The grass was VERY long for this video clip. Mike assures us that the aircraft lands like a dream, and the near nose over was due entirely to the long grass. We hope to add later video when Mike is able to get us some footage off asphalt, but didn't want to delay getting this great article into your hands!
The video was shot on a beautiful early morning, but the wind was about 12-15mph. It handles it pretty well, but you do see it get pushed around a little. Also, the long grass affected the landing. E*Models also has an excellent video of the Air Tractor on their site.
Scale aircraft are always high on my list and it is great that we have offerings from a great kit manufacturer. The E*MODELS AT802 is very easy to build. If you have not seen the quality and fit of the current laser cut models you must consider one of these amazing kits. The cutting was accurate and the included instructions and full size plans made this an easy build.
The flight performance is similarly impressive. It is calm and sedate and looks amazing in the air. Basic maneuvers are no problem either, but advanced aerobatics are not this plane's design or direction.
Playing with the flaps had a grin on my face for days after the first flight. They are very effective and create the drag and lift you need for amazingly short take offs and remarkably slow landing speeds. I have never flown a plane that required so little elevator mixing to keep the plane from pitching on application of flaps.
This amazing Air Tractor 802 would make an excellent addition to your hangar, I highly recommend it.
I just wanted to thank my good friend Doug Cohen with help on the paint as well as the pilot figure and chairs. He is an amazingly talented model designer and builder himself and his paint work makes my models look good! It should also be noted that he too had a big grin on his face after flying the AT802.
Check out the full line of E*STAR Models. They have many planes not commonly modeled and I am very pleased with the quick assembly times and true scale lines. If you have not built a kit before, do not let that lead you away from one of these great models. They are very easy to build look fantastic in the air. Flight performance is also excellent, pick one of these kits up today!Last edited by AMCross; Jul 28, 2006 at 02:38 PM..
Excellent job on the review. I love building kits(yes there are those of out there) and I have eyed some of there kits in the past but never picked any up. Even with some of the heavier balsa they might use it looks like they have used an extensive amount of lightening holes where possible.
Nice job as always Mike, thanks for the terrific review on this one.
The kit is a dream. Some of the best laser cutting I have ever seen. The quality of the balsa was very very good.
I am glad to know we still have a few builders out and about.....
Look at their new Fi-156 Storch! I am in love with it! I have five in the build queue so I just can't handle another (at least now.....) but someday...
I very much enjoyed this review! Good job. All the information I look for in a review was there. Thanks so much for providing the useful information! :-)
One, small, small thing; you might want to check your metric and Imperial conversions, some don't appear correct. Just a small point, but some are off just a little.
Again, excellent job.
Ken Myers, Lexington/Croswell, MI USA
Mike, very nice review! Really in depth, and great pic's to go along with the writeup.
If I didn't already have too large a backlog of kits to build, and repairs to do, I would definitely be looking to buy one of these firefighting 'Tractors! Coincidentally, I just heard on the news that one of the small airports near here is putting in a "single engined fire fighting aircraft base" I have to wonder if this will be the plane put in use there. This is kind of unusual in these parts, as in recent history, big, multi-engined retardant bombers are all we see, mostly Neptunes now, plus some helicopters with buckets or snorkle systems.
Thanks for a great review!
It is a great airplane - I did quite a bit of research on the web and Canada uses them in the FPL (Forest Protection Limited). I know Boise uses them also, and I think you will see them more and more. Cost of operation has got to be considerably lower than the vintage aircraft used now...
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