ARF

Precision Aerobatics Katana MD Build Notes

Daniel Switkin — Sat, 11 Jul 2009 10:19:36 -0500

The Katana MD is especially good looking in red.

Continuing in our Builds Notes series, this is my experience assembling the Precision Aerobatics Katana MD. This 46" wingspan acrobat is a premium-quality ARF, with a substantial amount of work done at the factory, and a unique carbon fiber reinforced balsa and plywood design.

Rather than writing full reviews, these Build Notes articles focus on the build steps, kit quality, and workarounds for common problems you might encounter.

Pluses:

The ailerons are the best of any ARF I've built. They are not only hinged at the factory, but rotate in a pocket such that there's no gap.
The canopy is magnetic and factory-assembled, no work to be done at all.
The build quality is very good. Both the internal structure and the covering were well done.
The instructions provide a good amount of detail, but the photos are too small, and black and white.
The motor box is pre-drilled for the Thrust 30 motor, which just barely squeezes in from the bottom, but otherwise installs easily.

The cowl is very attractive, but it's a shame it's not magnetic.

This is how the ailerons come from the factory - very nice.

The magnetic, one-piece canopy. Looks great and makes changing batteries easier.

Minuses:

The wheels didn't fit on the axles. I had to ream them out to double the size of the opening.
The main landing gear hardware was different than in the manual, and it used large washers which hit the curve in the gear and didn't sit flat.
The pull-pull hardware did not have enough threads on it, so that it would not clamp down on the carbon fiber servo horn. I had to add some washers.
The aileron and elevator linkages are just too much work and not adjustable when finished. They require wrapping a z-bend with thread and using CA to glue it to a carbon rod, and then using heat shrink tubing to strengthen it.
Fitting the cowl was a hassle and the screws don't look very good. At this price I'd like to see a magnetic cowl, completed at the factory, that just snaps on like the canopy with zero work.
I installed both nylon wing bolts as described in the manual, seating the heads completely flat, but when attaching the wings, both bolts were off by 1/8 inch. I had to bend them significantly to slide the wings on.
The factory made light cuts for the control surface hinges, but they were up to 1/2" off between the control surface and the matching stabilizer. They should be cut correctly or not at all.
The rudder and elevator are supposed to be sealed with clear heat shrink, which is not only tedious, but many ARF builders don't own an iron.
The battery tray may not be tall enough for a 3S LiPo which has spacers between the cells. Plan on using thinner packs.
The carbon fiber stickers on the fuse were peeling up in a number of places.

Notice the washers added on the pull-pull arm.

The black stickers were peeling up in a few places.

Thicker 3S LiPo packs are hard to install and may not fit at all.

Tips:

Replace the aileron and elevator linkages with threaded rod and clevises. These weigh only 2.6 grams each, compared to about 1 gram for the stock hardware, but are much easier to set up.
Insert a wing half on the carbon spar before gluing the nylon wing bolt. Bring the wing close to the fuselage, so that the wing bolt can be aligned with its hole, before applying CA.
Use self-adhesive clear covering to seal the rudder and elevator hinge gaps.
Be careful when using a 2.4 GHz receiver in the Katana, due to possible carbon fiber interference. Make sure to use a full range receiver with at least two antennas, pointed at 90 degrees to each other.
The instructions suggest CA for attaching the stabilizers. I recommend using epoxy for a stronger bond.
Make sure that the lowest rudder hinge will not interfere with the pull-pull control horn.
Check that the servo extension to the elevator servo does not interfere with the pull-pull cables for the rudder.

A shot of the elevator servo wire and the pull-pull cables.

Notice how the washer hits the curve in the landing gear.

Provided linkages at top, replacements on bottom.

Then go have fun! You can also check out Katana MD videos on YouTube or the main Katana MD thread on RCGroups.

MS Composit Pitts S2 Bulldog Review

Daniel Switkin — Thu, 01 Jan 2009 14:02:33 -0600

Specifications

Wingspan	33.5 in.
Wing Area	Approx. 508 sq. inches
Weight	18 oz. AUW
Wing Loading	5.1 oz./sq. foot
Length	33.5 in.
Electric Motor Requirements	200 Watt brushless motor, 18A ESC, 3S LiPo 1000-1500 mAh
Radio Required	Four channels, 3-4 micro servos
Street Price	$80 USD

The MS Composit Pitts S2 Bulldog is a park flier-sized foam biplane with a true airfoil. The majority of the plane is made of heavy-duty EPP foam, with the exception of the tail group (stabilizers, elevator, and rudder), which is Depron. The kit comes prepainted with a yellow and black scheme and the basic hardware needed, and comes in a simple bag.

The entire kit comes in a bag.

All of the kit parts before starting construction.

Right away, you'll notice that this model has a lot of potential, and also a number of shortcomings. I'll skip to the end of the review a bit by saying that if you make a number of replacements and modifications, this can be a great flying plane. However, the kit as sold off the shelf is only mediocre.

The upgraded wheels on the left, the stock plastic ones on the right.

Let's get a few negative things out of the way up front. The manual is quite poor compared to other manufacturers. This eight page leaflet is vague and meant for experienced builders, and will leave beginners used to a step-by-step manual out of luck. Fortunately, there's not as much work to do as with a balsa ARF.

The included wheels are just lightweight plastic discs, and are fragile to boot. Plan on replacing them with some real rubber wheels, or moving the aileron servo(s) to the top of the bottom wing, and flying without gear. If you do attach the landing gear, you'll want to bend it forward, as the stock position will cause the plane to nose over on almost every landing.

Building

I began building with the wings. The bottom wing comes as one piece, while the top comes in two halves which need to be glued. Although the manual suggests CA with kicker, I used UHU for all similar steps with great results.

Cutting the ailerons out of the wing cores.

Hinging the ailerons with Transpore tape.

Transpore and Blenderm tapes compared.

The Bulldog has four working ailerons, which makes it great for rolls. MS Composit cuts their wings such that the ailerons are built it - the foam itself is the hinge. I didn't care for this arrangement, as it makes the surfaces stiffer than necessary, and more likely to warp when moved. I decided to cut the ailerons free like most other foamies. I applied a small amount of UHU to the foam before using Transpore tape for the hinge. If you have Blenderm on hand, it will work at least as well if not better.

EPP wings have a natural tendency to flex, and like many foamies, these need to be stiffened. MS Composit has a very clever and inexpensive way of doing this. First you cut a slot 2-3 mm deep from wingtip to wingtip. Then you insert a length of string (included in the kit) into the slot, and soak it in thin CA. The string gets hard almost instantly and is quite effective in preventing flex. Many people choose to substitute carbon fiber instead, but it's not necessary.

Using string and CA to stiffen the wings.

The string is used on top and bottom, then trimmed.

The Depron tail is somewhat disappointing, being more fragile than the rest of the plane. I would have preferred EPP, or EPP covered with a plastic film, the way the ElectriFly Yak 55 does. As it is, the rudder and elevator both need to be cut out from their stabilizers and bevelled at 45 degrees before being hinged. I found the best way to do this was to make a 90 degree cut to separate the pieces, then hold the piece on an angle and sand it down to create the bevel.

The beveled edges on the rudder and vertical stabilizer.

I would not have cut the elevator backwards if the graphics had been face up.

Plenty of throw on the rudder.

At this point I have to confess to a building mistake which is entirely my fault. I happened to cut the elevator out with the graphics facing down. By not paying attention, I cut it the wrong way. That is, I made the stabilizer oversized and the control surface undersized. While it functions fine, a serious 3D pilot would no doubt find this setup lacking. The lesson is, pay attention: the edge with the notch is part of the elevator, and faces the rear of the plane.

The elevator slides into a slot in the fuselage and secures easily. However the vertical stab and rudder attach poorly. The stabilizer simply abuts the top of the fuselage and is glued there, which has no strength. A better design would have been one or two tabs on the stabilizer which would lock into holes in the top of the fuse. The rudder has a single hinge into the fuselage which is fine.

I used this stronger hinge to connect the rudder.

The assembled tail with the too-small elevator.

Things are starting to shape up.

Installing the servos takes some improvisation. If you're used to scratch building foamies, this will be second nature, but for everyone else it might be disconcerting. To start with, the manual uses one aileron servo for all four surfaces. I don't like the geometry of these setups, and wanted more torque, so I decided to use two Futaba S3110s for the ailerons with a Y cable.

This step is easier to do before attaching the bottom wing to the fuselage. The holes for the servos need to be cut out, with special care not to cut too deeply. You could also mount the servos on their sides if desired. I spaced them out as much as possible without adding extensions so that the force of the linkage would be closer to the center of the control surface. If you place the servos (and hence the control horn) too far inboard, the ailerons will bend excessively. Even with my setup I found the ailerons warp rather than staying flat while deflected. One solution is to add carbon fiber strips to the trailing edges.

I anchored the bottom wing with two carbon rods.

The Y cable to the aileron servos, with nice straight linkages.

The placement of the elevator and rudder servos is also up to you. I used the approximate locations suggested by the manual, choosing the height of each to get a straight shot to the control horn. One thing I didn't care for is the way the pushrods and their plastic tubes are supposed to be sunk into the fuselage. This bends them a fair amount and adds some friction. In the end I went with it, but standoffs would have worked better. On the upside, the pushrods come with z-bends already made, and adjustable pushrod keepers which make setting the linkages easy. I glued all four servos in place with a hot glue gun to make them easy to remove if needed.

Cutting a hole for one of the tail servos.

The servo lead from the other tail servo needs to come through the fuselage to reach the receiver.

The pushrods can be cut down once installed.

The tail control surfaces hook up in the standard way.

Attaching the wings is not hard but it is important to pay attention to the alignment. Again I used UHU plus a lot of weight to keep everything flat. The struts between the wings interfered a bit with the top ailerons but were easy to trim back. The linkages between the top and bottom ailerons are thin metal and tend to bend a bit. You may want to replace them with carbon rod.

Using lots of weight to glue the wings.

The stock connector between the top and bottom ailerons.

Installing the power system.

Close up of the power system.

All the electronics mounted on one side.

Just one servo and the battery on the other.

For power I used the BP Hobbies 2217-9 brushless motor and the ElectriFly SS-25 ESC, which I happened to have on hand. The plastic motor mount does not secure well to the foam - you may need to experiment to make sure it is retained well. This motor is a bit on the heavy side at 2.6 ounces. I put the ESC and receiver on the opposite side to offset the battery, although lateral CG still proved to be a problem. Use the flattest three cell LiPo you can to prevent unwanted roll towards the battery, and attach it with a velcro strip so you can adjust the longitudinal CG (front to back).

Flying

Since I fly off grass, I always hand launch the Bulldog. There's room to grab the fuselage in front of the top wing, but be careful of the prop. I use an APC 10x4.7 SF with good results. The BP motor has plenty of power to climb out with a gentle toss.

For the maiden I used a 3S 1500 mAh pack, which worked but felt heavy in the air. A 1250 mAh LiPo felt better, and convinced me to order some 1000 mAh packs, which help offset the weight of the motor. With these smallest packs I set my timer at 8.5 minutes and never use more than 80% of the capacity. With very aggressive flying 7.5 minutes is still doable.

The Bulldog ready to hand launch.

Doing a harrier around the field.

Looks pretty...

... and flies great.

Flying the Bulldog makes the lousy hardware, upgrades, and modifications worthwhile. It's stable and floats very well at slow speeds. The roll rate is great as you would expect from four ailerons, and there's plenty of rudder available. Although my setup will hover and perform outside loops, it doesn't punch out strongly the way a 3D plane should. I'd suggest a lighter motor and leaving off the landing gear if you want that kind of performance.

Landings are pretty easy. I tend to keep a little power on, but you could glide in deadstick too. As I mentioned earlier, the stock landing gear is positioned too far back, and will cause the plane to nose over. You may be able to prevent this with full up elevator, but I just bent the gear forwards.

Long Term Report

I've been flying the Bulldog for four months now, long enough to get a good feeling for its durability. Overall it's pretty tough. Those nose over landings never did any harm, and the wings can handle an impact well. I don't hesitate to fly it on windy days, unlike my wood planes. The Depron tail surfaces can break though, especially the thinnest part of the rudder, next to the control horn.

Look how the motor's torque twisted the wires!

Another shot of the broken nose.

Notice the scotch tape on the Depron rudder.

Both chopsticks were inserted this far.

The one notable exception to this toughness is the nose. When built stock, it is almost guaranteed to snap in a crash. The simplest solution is to use some wood chopsticks or BBQ skewers and run them through the motor mount, down through the nose. Try to get it past the plastic landing gear mount to make the entire nose rigid. A side benefit of using chopsticks is that the motor mount will glue onto them in addition to the foam, for a stronger bond.

Conclusion

The Pitts S2 Bulldog is a lot of fun and a good flier. It's a bit expensive for what you get, and some of the hardware is junk, but it can be turned into a great plane with a little time and effort.

Be sure to check out this excellent build thread on RCGroups for additional upgrades and changes you can make, like building EPP tail surfaces.

Carl Goldberg Products Protege ARF Airplane Overview

Zero — Sat, 08 Nov 2008 18:13:52 -0600

Carl Goldberg Products Protege ARF Airplane

The Carl Goldberg Products Protege ARF Airplane is a great ARF for the beginning flyer ready for their first trainer. Maybe you have flown some park flyers with the sailplane like wings and now your ready for some training at your local field but want something already assembled - well this would be a great choice. You will need to install the engine, radio and make all the adjustments; but after that you will have a quality balsa plane that most instructors will enjoy flying as well.

At 71.5" in wingspan, this plane gives you the size you need as a beginner or immediate to keep track of the orientation. This is important for many flyers since even experienced flyers sometimes loose the orientation during maneuvers or when the plane gets a bit out of sight. This model has nice hardware included as well as features quality balsa construction. You will enjoy this airplane as you advance and who knows it may remain a favorite for years to come. Check out all the specifications and details on Carl Goldberg's website.

Carl Goldberg Products 67" Edge 540 ARF Airplane Overview

Zero — Fri, 24 Oct 2008 17:46:50 -0500

Carl Goldberg Products 67" Edge 540 ARF

The Carl Goldberg Products 67" Edge 540 ARF Airplane is an exciting 67" aerobatic nitro plane. The website has a great video showing the awesome performance and looks of this plane. As an ARF you will be flying it quickly and with Carl Goldberg quality you know you will have a excellent results.

Built for a 4-stroke 1.2 size engine, but you could also use a .6 to .9 2-stroke, the Carl Goldberg Products 67" Edge 540 ARF Airplane is a good choice for an advanced weekend flyer or the serious 3-D pilot. The plane has been built with laser cut parts and features an all-wood airframe. It also has aluminum landing gear, fiberglass cowl and fiberglass wheel pants.

The video below comes from the official website where you can also take a look at the instruction manual which shows all the components you will need to complete the model.

Specifications

Wingspan: 67"
Wing Area: 854 Sq. In.
Fuse Length: 64"
Flying Weight: 8-9 lbs.
Power: 2-stroke .60-.90 or 4-stroke .90-1.20
Radio:
4 - Channel Radio
6 - Servos

Top Flite AT-6 Texan ARF R/C Airplane Overview

fastie — Thu, 25 Sep 2008 06:00:00 -0500

Top Flite AT-6 Texan ARF In Action

The Top Flite AT-6 Texan ARF is an exciting entry into the scale warbirds category for Top Flite. This plane was originally a WWII trainer for many developing their skills for military combat. With it’s great scale looks and features, you will feel as if you are part of this history when you take the field and experience it’s flight characteristics. Top Flite calls this a “Gold Edition ARF” which means that there are many scale parts and features to add to the great looks of this military warbird.

Highlights of the Top Flite AT-6 Texan ARF R/C Airplane

Nicely covered parts with good scale looks.

The Top Flite AT-6 Texan ARF includes many nice features as explained by Top Flite including “built-up and sheeted wood construction with fiberglass cowl and aluminum spinner, sturdy mechanical retractable landing gear, historically accurate, high visibility WWII Navy trim scheme and assembles in 18-25 hours.” The AT-6 texan has nice scale features with it’s “Gold Edition” designation such as realistic wheel covers, replica radial engine, greenhouse canopy, and a great realistic color scheme. The plane can be powered by your choice of a 2-cycle or a 4-cycle engine and Top Flite suggests the O.S. Engines such as the 2-cycle 61FX or the 4-cycle 91S II. The planes performance is well suited to those jus moving up to the low winged category and with an interest in military warbirds. The plane features ailerons and flaps to help control your R/C plane with expert skill. See Top Flite’s complete details on their website:

Specifications:

Scale Detail

Stock Number:TOPA0965
Wingspan: 69 in (1755 mm)
Wing Area: 730 in² (47.1 dm²)
Weight: 8.5-9.5 lb (3.8-4.3 kg)
Wing Loading: 27-30 oz/ft² (82-91 g/dm²)
Length: 51 in (1295 mm)
Requires: 6-channel radio w/8 servos & 2-stroke .61cu in (10 cc) or 4-stroke .70-.91 cu in (11.5-15 cc) engine.

For more information, check out the Top Flight website.

Great Planes Edge 540 3D Overview

Zero — Sun, 14 Sep 2008 18:01:53 -0500

Edge 540 3D ARF by Great Planes

The Edge 540 3D is one of the latest additions to the Performance Series from Great Planes. It is an ARF and has really nice looks since it is based on the popular international aerobatic plane which competes in the real Unlimited class circuit. Excellent Great Planes quality, super 3D plane performance and built to be lightweight without sacrificing durability make this model one to add to your short list for your next build.

Construction and Required Equipment

Nicely covered comes ready to assemble

The Edge 540 3D ARF comes nicely packaged and ready to assemble. You will need some extensive accessories to build this model which is the norm for a plane of this size. The Great Planes website has the product manual available which is great to have before you purchase so that you are able to plan the list of accessories to complete the model. The model also has the option of being built as a brushless electric plane, glow power, or gas powered. The plane features nice materials including a fiberglass cowl, sheeted foam core construction and easy to see trim scheme on the underside of the model. When considering electronics for this model, keep in mind that standard servos are not adequate except for the throttle servo. You need to use servos that have a high torque rating with a minimum of 98 oz-in as per the instruction manual. The Edge 540 3D is a very capable aerobatic model and as such needs extra attention to this details to achieve the best performance. If you are looking for a large size 3D/sport plane with great performance and looks, this is one model you need to consider.

Model Specifications:

Fiberglass cowl and nice scale looks

Wingspan: 78 in (1980mm)
Wing Area: 1088 sq in (70.2 dm^2)
Weight: 13-15 lbs (5900 to 6800 g)
Wing Loading: 28 - 32 oz/sq ft (84 - 97 g/dm^2)
Length 74.5 in (1890 mm)

Requires: Radio: 4-channel minimum, 6 to 7 servos, 1.6 to 1.8 cu-in (26-30 cc) Two Stroke, 1.8 - 2.1 cu-in. (30 - 34 cc) four-stroke, 1.9 - 2.6 cu. in. (32-43 cc) gas, 63-62-250 Rimfire out-runner motor

Top Flite B-25J Mitchell ARF Overview

William — Sun, 01 Jun 2008 17:02:39 -0500

I'll never admit to being lazy, so my reasoning for steering clear of most ARF models is due to taste. One look at the B-25J Mitchell ARF from Top Flite, however, makes me into a stressed riddled perfectionist. There are certain things in life that when you have them, you become the center of attention, the big shot. Like getting a 60 inch HD T.V. with over 3,000 worldwide channels.