The flying monkeys got me...

Helis, Fixed Wing, RC Sailing

AMA 957918

Pirate Kid Skeleton by RadDezigns.

Saturday, April 12, 2014

Skyline/Goldwing Sbach 342 60" Build Day #2

One long build day today! Got the Honey-Do list done this morning, and set to it!

 

Elevator installed. This is a single servo-U Bar system. The elevator servo is attached to the right elevator which it moves directly. The U-bar transfers the movement to the other elevator to which it's attached. One end of the U is in the right elevator, the other in the left elevator. If the elevators are not equally deflected, a roll force occurs as if they were ailerons. The hard steel I think they intended for the U-bar snapped when I shaped it, too brittle, and the softer steel rod (I think intended for throttle control rod not needed on an electric) torqued too much at full deflection. I ended up adding the left over hard steel rod (see below) as an anti-torque bar and it worked it great!

 

 

Clean install, you can see the silver U-Bar.

 


Elevator servo without extension. The aluminum control arm is standard length, shorter than the supplied fiberglass one. Inadequate throws, I mean, good, but not complete. The geometry is off with the servo end below the elevator carol horn.

 

So I modified the setup by laying the fiberglass arm over the aluminum arm.Perfect geometry.

 

 
Side view. Trimmed the screw ends for a cleaner look. Now get full throw range of motion.

 

 
Zaphod, sleeping on the job... Just can't get good help these days.

 

The aircraft, like many, benefits from an underside tail vent opening to improve ventilation across the motor, ESC and battery. I made that opening, and then created a louvre system to direct the air. I had seen this mod on RC Universe on this model and liked the way it looked. I had no idea how to make it but McGyvered a fairly decent set. First made a box that fit in the opening and created a jig for the louvers, cutting guide slits.

 

I added a scoop for the inside tail end to further direct air out the hole.

 

Super glued in construction then coated with alochol thinned epoxy for strength and sealing. I painted it matte black.

 

The vent opening. When I install the louvers I'll post a pic. I used the needle nose pliers to hold the bar in the grooves.

 

The anti-torque bar. I routered out a slot and dropped the bar in there, superglued it, and later coated it epoxy.

 

The other side.

 

In place before the cote covering. It lies parallel to and just aft of the U-bar, so gluing them together increases the support against torque.

 

After I put white cote over it, and voila, can't see nothin'.

 

Rudder and tail wheel assembly. Rudder control horns are fiberglass one piece. I am not fond of tail wheels that put the stress on the rudder and it's hinges. This design mitigates the stress with a sturdy stabilizing platform with three screws and the collar resting on the plate. I had to find an extra collar, there wasn't one in the kit. Went together nicely. I added a piece of nylon hinge material used for connecting the control surfaces across the bar as it goes up into the rudder to provide more support.

 

Sturdy. You can see the hinge material across the landing gear rod on the rudder.

 

 
I went to a lot of trouble to put the wheel pants on the correct sides. Fail.

 

Fixed. That's better.

 

First time resting in all three landing gear.

 

Takes up the whole breakfast table.

 

Rudder servo with the control arm and wire attachments installed. I haven't used aluminum control horns before, worried about fit. I got Hitec C1 21T spline, and they all had to be tapped (lightly hammered actually) to fit. This one went on by hand, snugly. All of the centered nicely without sub trim.

 

I mark the couplings with red Sharpie to show when I reach 50% of the length so I don't weaken the coupling.

 

 
When setting up the rudder pull-pull system it's important to center everything. I locked the rudder.

 

 
Rudder system is complete.

 

 
Looking aft through the fuselage at the pull-pull system. The wires cross to ensure they exit the fuselage aft in line with the rudder control horns. Snug tension, not stressed. I later secured the elevator servo wire to keep it off the wires.

 

The distance from the motor box to the end of the cowl was 113mm. The motor tfrom base plate to the prop rotor base was 60mm. I had to come up with 53mm. I was annoyed, there is nothing in the instructions on this. I remembered there was a bag with a lot of wood frames in it for the gas tank in a fuel model. I opened it to see if there was some wood I could use, and there was a motor box extension of 50mm! I modified it slightly to make it stronger. I was able to put it together and sort out how I wanted to install it.

 

Measure twice,epoxy once. I measured and centered it (the holes for the center were not centered, glad I ignored them). Epoxied into place and added a M4 bolt and self anchoring nut to ensure it never comes off.

 

Perfect fit! I love it when the engineering math works out!

 

Motor installed. Again, perfect fit! Math, baby! The HobbyWing FunFly 80A HV ESC in place. Plenty of ventilation!

 

I was worried that the deck the reciever was on was kinda thin, and it cracked when I pressed the reciever Velcro into place, so I added a piece of thin plywood as a deck, both repairing the crack and adding strength. Spektrum AR600 DSMX receiver. I like to use short extensions for the aileron servos so I don't mess with the reciever.

 

All the electronics in place. Forward the battery leads are lengthened with segments I salvaged from old batteries. The tap for the BEC is up front and the Exceed RC 6V BEC is Velcroed to the bulkhead (it can be seen in the lower right hand corner, forward in the fuse). The ESC has a spark eliminator circuit built into the wiring harness, but it's too far forward so I can't use it

 

I always take the motor stickers off since the heat will make it fall off anyway, and tape it to the firewall.

 

Long but fruitful build day!

 

UPDATE: Installed the louvers. Look better in real life.

 

 

Friday, April 11, 2014

Grounded

All of my 4S batteries are toast... recharged and retested them. The wattmeter showed nice numbers until the battery ran beyond a few secs then wild fluctuations in voltage and amps out as the motor waxed and waned. None of them are behaving properly. Threw a 3S on there and it worked fine. I am pretty sure it's not the ESC, But not throwing away the batteries until the new ones test running well. Gnashing of teeth as I ordered new 4S 3300mAh 25-50C Turnigy Nono-tech batteries. Few options...

Guess I need to get the Sbach up and running and maiden her without finishing up getting my flying fingers back fully. thankfully those batteries are fine.

 

UPDATE: screw it... I don't like the cheap ESC in there now, ordered a HobbyWing FunFly 60A with SBEC.

Thursday, April 10, 2014

Skyline/Goldwing Sbach 60" Build Day #1

Today the Skyline/Goldwing Sbach 342 60" kit arrived via USPS this afternoon. It took abut a week to get here from General Hobby in California. The instructions came on a mini-CD, a 12 page PDF. Not particilarly useful but some nice drawings to guide me on those parts unique to the plane. In general anyone with build experience can have this built in about 6 hours or so. Today I just did the wings and the landing gear.

The box was in fair shape with one bad puncture, but nothing damaged inside!

 

Top off un-boxing!

 

Everybody out!

 

Aileron hinged, servo installed, servo arm and control arm fitted. The control horns are sturdy fiberglass. I used Super Glue instead of epoxy. Hitec digital HS-5485hs all around. I actually centered the servo on the receiver, not just the servo tester, pirate flag installed, all set to go!

 

The aileron control rods are steel and were about 1 cm too long. I Dremeled off about 5 mm from each threaded end. The ball links need to be 108mm apart by my measure and were well over 120mm before modification. Fit perfectly after the fix with good thread engagement. I wish the rods were carbon fiber...

 


Top side of the right wing. Applied the decal and the mini pirate flag. My Brother computer printer label maker is in storage so my blog URL sticker on the aileron will have to wait...

 

Left wing same as the right wing...
Cats optional.

 

Annoyance. The letters "Sbach" are supposed to be black... This sticker is supposed to go on the white field of the left wing. It's also a bit smaller than it's supposed to be, and, well, white. I wrote General Hobby to see if they can send me the right one, but I suspect not. Trying to get one from China will not work either. I may have to McGyver something if I can't find the right one online. UPDATE: I emailed General Hobby last night and this morning they responded they are sending me the correct sheet. I realized this isn't really their problem and really appreciate their stepping up!

 

I made another modification here. The instructions called for the wheel to be held in place by an opposing relatively flat nut and a nylon lock nut, and a second lock nut holding the axle to the landing gear strut.. This did not allow for enough space between the wheel and the wheel pant in dry fit; the wheel rubbed the pant. I could have Dremeled down the pant, but I didn't want to weaken it at all, so I replaced the flatter nut with another M4 nylon lock nut I had, and the two lock nuts created a perfect fit with nice clearance for the wheel from the pant.

 

 

The wheel pant installed. Easy peasy.

 

It was late and I am in no rush, so I stopped for the night. I put all the plane parts back in the box to keep the cats from chewing on them. I finally hung the other plane and my helis up to keep them at bay.

 

Tomorrow I have to wait for the cable guy, so will take the time to do the tail assembly, including the rudder and elevator servos, and if I get time will start on the motor and electrical harness installation, install the landing gear, tighten up the cote and test everything. I could be done tomorrow!