50cc Sbach 342 by RCX - Build Thread

[TrojanMan]

I was lucky enough to receive a pre-production 50cc Sbach from RC Extreme Machines based out of Lahore Pakistan. They guys there have worked hard to bring an accurate scale model of the Sbach 342 to the RC market. Keep in mind that quite a few changes have been made and that this model was one of the first. It was fun model to assemble and I had it ready to fly in only 2 days of assembly.

1st step, I picked up the crate from the shipping company. It was in near perfect condition after making its way from Pakistan to Oklahoma. I understand the production aircraft will be shipped in 2 to 3 boxes to reduce shipping size and costs. The crate that the airplane was in was well built and protected the airframe so it arrived unscathed. (see pics in next post)

RCX Website

[TrojanMan]

The next step was to unpack and inspect all the parts of the aircraft. Everything was in perfect shape. Well packaged and well marked parts bags contain all the smaller items. Wings, stabs, fuselage, Cowl and all other parts made the journey without damage.

[TrojanMan]

Since the manual had not been written I started out by getting the airframe up on its gear.

The landing gear was pre-drilled and All I had to do was install the Dubro axles, Wheels and collars. The uniquely shaped wheel pants installed like most. It is much easier to get everything put together before mounting the main gear on the fuselage. 4 bolts and washers from the pre-marked bag and the main gear was on.

The tail wheel assembly was ready to install right out of the package. There were 2 pre installed blind nuts in the tail and the bolts were included in the same bag as the tail wheel.

Presto, it's now on the gear!

Added note, The main gear is well made and appears to be molded with carbon and not a wet layup.

[TrojanMan]

I then decided to work on the Stab/Elevator Assembly's. The hinges were pre-glued and the carbon horns were pre-installed.
I used a soldering iron to open up the holes for the mounting bolts that hold the stab to the fuselage. The elevator servos install in the rear of the fuselage. The locations were already cut out and all I had to do was mount the servos in place along with attaching a servo extension. The Sbach has a pre installed servo wire tube and strings to pull the wires through. Makes for a very easy install.
The pushrods were pre assembled with carbon tubes that are already glued over the pushrods and were already the correct length. Next was to bolt the supplied servo arms to a stock servo wheel with the supplied bolts and nuts. Attach the arm to the pushrod assembly with the supplied 4-40 bolt and nut. Then install the ball link to the control horn in the elevator with a 4-40 bolt and nut. Center the servo, put the servo arm on the servo, use the carbon tube to mount the stabs, install the bolts and washers for the stab into the fuselage. And that part is done!

[TrojanMan]

The rudder was next. This model came shipped with the rudder and hinges already pre-glued. I understand that the production models will not have the rudder installed to keep the total length down and shipping costs manageable.

As in the elevators, the control horns were pre installed in the rudder. Also the pull pull cables were pre-made and installed. All that was necessary was to mount the servo in the carbon servo tray inside the fuselage and install a servo wheel onto the carbon servo arm inside the airframe. Then mount the servo arm onto the servo. That is all that is needed to complete this step!

[TrojanMan]

I then moved on to the wings. Just like the stabs and rudder, the wings had the control horns installed and the hinges were pre-glued. RCX had pre-installed a string to pull the servo wire through. It has small laser cut wooden airplanes on each end of the string.
I installed a servo extension on the servo wire and pulled it through with the above mentioned string. Drilled 4 holes for the servo and screwed it down. The push rod was already assembled with ball links on each end and a carbon tube over the rod to keep it from flexing. The pushrods were also the perfect length. Just like the elevator servo, you bold the servo arm to a servo wheel. Then using a 4-40 bolt attach the other end to the carbon control horns. The wing tube is carbon and appears to be very strong and light.

Do this a second time and the wings are completed.

[TrojanMan]

Moving on to the front end of the airplane.
The Fuel tank came pre installed with all the fuel lines and a fuel filler valve. The filler valve is just that, a filler. It is on a 3rd line and is not supplying the fuel to the engine. A very nice touch and well thought out. Also, the fuel tank is mounted at the cg location. The vent line was ran behind the tank, and ran down through the engine box and the tank is held in place with velcro straps.

The canopy/hatch assembly is mounted on hinges and opens to the right side of the airplane. It uses a very clever and well constructed latching mechanism that opens with a allen wrench or ball driver.

I mounted the receiver on the forward part of the carbon tray just behind and below the fuel tank with a voltage regulator just behind. This made for a pretty clean install and with the easy opening canopy I opted to not put a switch in for the receiver and just plug in the battery for every flight. Just keep a ball driver handy!

[TrojanMan]

Engine Installation

The Sbach come with plywood templates to mount either a DA-50 or a DLE-50/55. I had a DLE-55 on hand that I purchased from Charlie at Fox Manufacturing so I grabbed the appropriate template and held it to the firewall. I wan under the impression that the DA and DLE used the same mounting but the templates are slightly different. I used the large hole in the firewall and the template to position it correctly. I then drilled the four holes to mount the engine. It was a perfect fit and the engine bolted easily to the firewall with the engines supplied stand-offs.
I decided to mount the ignition on the right side of the engine box, held on with zip ties. and the battery on the left side, also with zip ties.

[TrojanMan]

Here is where I am at to this point. It doesn't take any time at all to get it to this stage. It looks like it is almost ready to fly and it is!

[maineflyer]

Looks Very good!! Great review TM

[TrojanMan]

Next is mounting the cowl. the cowl is held on with 4 bolts. 2 internally installed bolts at the top and 2 external bolts that mount from the bottom. It is a clean look and is strong. As you can see in the photos, the cowl is made with carbon reinforcements in several places. This make the cowl quite ridged but keeping it very light weight. Using a method that works for me, I taped a piece of construction paper to the bottom of the fusalage that extended past the engines cylinder. I traced the cylinder on the paper and then cut it out. I removed the engine, mounted the cowl and transfered the opening made in the template onto the cowl. Using a dremel cut off wheel and sanding drum I opened up the cowl. Be sure to use a dust mask at this stage so you don't breath the dust created. Not good.

This is my least favortie part of any build for some reason and the photos taken did not turn out. I have a couple of pictures on here from RCX and they show the process.

But the cowl did turn out great and I'll get more photos of the final product.

[TrojanMan]

Finally, Install the exhaust of choice. I used the standard muffler provided with the DLE. Install the cowl with the 4 mounting bolts. Drill the prop and the spinner back plate. Install said prop and spinner. I almost forgot to mention. The carbon spinner is included!. In fact most everything is included with this ARF.

Make sure everything is strapped down and we are pretty much ready to go.

The airplane balanced right on with the radio battery just in front of the wing tube. I mounted it right beside the fuel tank.

I feel confident that if you have your engine and radio gear on hand you could get this bird in the air in 10 to 12 hours. Of course some of us like to take a little more time. This is one airplane that is completed to a level that very few ARF's are. You can tell that this airplane was designed and built by modelers and there are many things already done that make you say "wow".

If there is something that I didn't include here please just ask. I will try and get more photos up as needed.

Jim

[TrojanMan]

A few extra photos of the Sbach.

[TrojanMan]

Field photos

[hangingbach]

hey great!! cant wait for the videos.