Slushy Fields

Too slushy... gone or frozen over would let me fly. The Du-Bro skis for the Stick and Cubby are on their way.

The slush really outlines the serious clumpiness at Joppa Hill Fields. Surely this affects the kids play as much as the landing gear on my planes?

RCGF 10cc Cylinder Head Changed Out

I ordered a new cylinder head from RCGF-USA for the 10cc engine whose spark threads had stripped. It arrived today and I installed it, and started the engine.

It oddly did not come with a new gasket, which would have been nice, so I took care removing the old one. After removing the old cylinder head, I oiled down the new one with WD40, slid the piston in (the piston ring passed easily this time. Bolted it in place, reinstalled the muffler/header, took her out and started her up. After she burned off the WD40 she ran just fine. There is some 4-cycling, but she is a new cylinder head. I put a Master Airscrew Scimitar 14x8 on her for the break in, then I may or may not put the 4-blade prop on. Who am I kidding? Of course I will eventually put the 4-blade prop back on...

I also learned a couple of things I can do to save the other head. I can try re-threading the 1/4-32 plug (of course my 40 piece tap and die set doesn't have that one so I had to order one from China).  I can also drill and sleeve the threads with a kit. I want to see if I can make the repair to the threads so I have a new skill and a working extra 10cc cylinder head. 

Ran half a tank at various speeds, tuned her a touch. I am off Saturday, so if weather permits I will fly her and continue the break in.

A Bad Bulkhead and RCGF Spark Threads Strip Again

I ran the engine today with the 14x8x4 prop and it didn't come flying apart. It started and ran fine, but stalled in idle after a few moments. During that time the prop was fine, stable, and tracked perfectly without bowing, and no vibration. The second time it stalled at idle I could not restart it. I took it into the shop and I removed the spark plug to check the ignition and it sparked, but inconsistently. I decided to replace the Hall sensor and it fixed the spark problem. The Hall sensor frame had snapped and in repairing it it sat a bit higher than I think it should. I could not get the sensor head out of the case, so I had to replace the entire thing, and I just happen to have a couple.

I noticed that when I removed the spark from the RCGF 10cc engine, I noticed a "spring" in the hole. It took me a moment to realize that the spark hole threads had stripped. This has happened before as RCGF had a problem with the early engines they supposedly fixed where the threads were too soft or something and kept stripping easily. I replaced the spark and it threaded "finger tight". I tried turning it over and gas poured out... I could twist the plug with my fingers, it would "tighten" and then a half twist and it was loose again.

I ordered a new cylinder head. I hope these replacement heads have better threads.

When I noticed that the threads were stripped, I was concerned that some pieces fell into the cylinder head. I decided I needed to remove the entire cylinder head. Two of the screws came out easily, but two were blocked by the muffler header screws. One of them had stripped a while back... so I had to remove the entire engine to find a way to get the muffler off, and had to remove the prop. One thing leads to another...

I pulled one screw of the header easily, the other I could not get any purchase on. I twisted the muffler and it loosened. I managed to twist it and the screw got looser and looser, and eventually I could not turn it anymore. I grabbed it with a pair of needle nose pliers and managed to completely remove it! I got the cylinder head off and it was heavily carboned. The cylinder head was rough, like 60 grit. I used Gum-out and cleaned it all to nearly completely shiny. It took a few minutes to get the piston ring back into the cylinder head, but then it moved nicely. I used some WD40 to lubricate it. I put it all back together. That's when I tried to put the plug back in. 

Waiting for the new cylinder head. 

Earlier I kept hearing something rattling around and wondered if there was damage inside the frame where the fuse had been cracked. I opened the access panel I had made when I first built the plane, and found that the frame behind the firewall and in front of the gas tank was broken. I cut some ply into a U shape and divided it to get it in. Epoxied it. I added a couple of cross braces on the top, bottom and middle. This was easily done and came out perfect. This pic is before the crass braces. 

When the cylinder head is repaired, I hope to tune the engine for the new prop. Its very light. I have no idea if I will keep the 4 blade, it was more for fun than anything else. I wanted to check the static thrust, but the engine stopped working before I could.

So she sits on the bench. Hopefully the cylinder head will get here soon.

Oh, please, you would if you could!

It called to me...

Yeah. 4 blade 14x8x4, baby. She was flying a 13x8x3.

You know you would too, if you could. You know it. Especially you, Gary Hoffman.

I am not sure how it will work, but I will run it tomorrow. Its a prop from an electric FMS P-51 Mustang. I had flown it on the doomed VQ Models P-51. Same spinner, new blades. It was on the shelf. I had to. I had no choice. I honestly don't even know if the blades had enough clearance, especially with the tall grass, but she also had a 14x8 twin blade on her (Master Airscrew Scimitar).

I completed the repair on the side wall. It was still a little weak after the epoxy, so I laid down a thin sheet of balsa. 

I also kept the stabilization system on. I figured out how to set up the remote cut, so the default is OFF. I will take her up and turn it on. I have a feeling it was just too sensitive and was over controlling itself.  I lowered the gains. We'll see, but its an unsolved problem and I need to solve it... Found a couple of tears in the cote on the vertical stab, fixed them too. She is flight ready. I'll try the prop at home, but if weather permits, I'll head out to Joppa in the morning.

So this happened...

First flight with my Big Stick being equipped with the Hobby King Orange 3-Axis Stabilization system.

What an incredibly well designed plane, sturdy as hell. The prop took a devastating hit, the nose buried about 6 inches into the dirt (thankfully it was soft), the wing attachment hard point came off as designed and will need to be repaired but there is no damage to the wing, and the port side of the fuse just aft of the engine cracked up. Its all but already repaired.  Luke on video.

Really, that's it. I thought she'd be toothpicks.

Broke clean off.

Spinner is about 4 inches down there, had to dig it out.

The only part of the fuse to take damage.

Close up.

Epoxy, a few pieces of balsa. I will sand it down and lay a thin sheet of fiberglass or thin balsa down.

I'll add photos as the work progresses, including repair of the wing hard point. 

I still have the stabilization system in the plane. There is supposed to be a way to rig a cut-off using the AUX channel, but I need to read the manual. If I can't rig one I will pull the system out and skip it. I checked the settings and they all move in the correct direction. Was there too much vibration? I always check the control surfaces before takeoff and they were also all appropriate. There was no wind. No idea WTF happened but it was all I could do to keep her out of the trees.

I will need to patch a hole in the underside of the wing... I dropped prop on it on the workbench. 

Wait until you see what I plan to put on for a prop!

Happy Turkey Day!

Futaba Micro Spline 21T....Maybe

I  wrote about the issues trying to find the spline to fit the Tactic Mircro TSX-10 Servos. I had purchased Dubro Futaba Micro Spline compatible servo arms and they were too small. At the same time I bought some aluminum arms for the same spline. Since the Dubros did not fit I didn't  expect the aluminum ones to, so when they didn't fit easily I was dismayed. I am still waiting to hear from Hobbico about what the proper spline is...

Today waiting for another project to dry, I retried the aluminum arms. With a bit more effort they actually fit quite snug. I removed them, and nothing had crushed to give the illusion of fit. I had already replaced the rudder and elevator with the original plastic arms since they were bolted on to extensions so the lack of width at the end didn't matter. I installed the aileron arms, and had to replace the carbon fiber rods with steel, but they work fine. Any more range of motion and they would come right off.

Aileron. From China on Ebay.

Elevator. Original plastic on epoxy extender.

She is ready to fly!

UPDATE (11/23/16): Hobbico had no idea what the spline is, but they got one and now know its 20T. They are checking to see what splines will be compatible. I am not aware of any 20T micro spline...

Big Stick Wing Repair

Several days ago the wing came off the Big Stick after the left tip touched on landing. It cracked the mid-seam and tore off the front attachment knob thingy. The simple job got complex when a lack of attention on my part lead to further damage to the top of the wing.

I epoxied the underside seam and used my drill as a weight to flex it down.

I pulled back the cote from the center and laid down 3 layers of fine mesh fiberglass cloth with alcohol thinned epoxy as the resin.

Not sure how secure the top was, I laid down 2 layers of fiberglass.

Sanded it flat.

Same on the underside.

While that set for 24 hrs, I examined the broken forward wing attachment. There should be a section of plywood that juts out; that goes into the fuse to secure the wing's front edge, the back end being held by wing screws.

Cut it clean as a right angle. You don't want this too strong or instead of giving way as it did here, the energy will break up the wing or fuse.

Epoxied in a new block.

Epoxied in some side supports. I sanded down the aft parts so they were flush with the attachment hard point.

In trying to sand down the very thick epoxy on top I didn't take into account the slight V in the center. The sander ground down a bit of balsa on wither side of center. I had to peel back the cote and fill it with wood filler. It provides some strength over Hobby-lite, of which mine had dried out.

The bottom finished. I painted the forward attachment with black gloss enamel. I used black cote aft as I didn't want to waste the red.

Ran a piece of black tape across the front and back as a soft shim for better fit.

The top is nice and smooth, re-coted, and applied a new sticker.

I had checked the fit of the forward attachment several times as I rebuilt it. I wholly expect that when I go to put it on, it will not fit and snap clean off... we'll see. Waiting for that black paint to dry.

Toying with putting a stabilizer on it.

Looking forward to flying her again soon!