The flying monkeys got me...

Helis and fixed wing

AMA 957918
IRCHA 4345
AMA Intro Pilot Instructor

Saturday, January 7, 2017

Skiis, Hardpoint and Stabilization Success

Got out and up yesterday. Cold 30 deg in the sun, calm with mild variable gusts. It was time to test the skiis, the newly revised wing hardpoint and the stabilization system on the 10cc BigbStik.

A light snow in the morning, but most of the deeper snow has melted off. At this side it's shallow with grass poking through, on the far side about 6". I walked across to fly from the other side as is my new preferred side. It's that hard to walk on iced over snow

The new hardpoint addition. I redid the post on the wing, and added this extra piece to secure the anterior edge of the wing. That wing post hard point takes a lot of forces and I didn't want to depend on it alone. Worked perfectly, even in wind and aerobatics.

Wing attached. You can see how the wings snugs up under that new piece.

Today's tarmac. Using the wing bag to kneel on, trying not to make footholds in front of the plane so it can slide out for takeoff.

One of the issues with the skiis is that they offer virtually no resistance to thrust, so even at idle the plane wants to scoot off at high speed. This also makes roll out after landing a bare knuckler. This was a problem today. I gave it some thought when I got home and decided to use some of the L-rod I have for making vortex fences and CA'd some Vs to create a little resistance.

Tail ski. The hollow hardpoint twists against the Shea of being used as a tail wheel, so I filled it with epoxy.

Mains. Trying one set each side.

In flying with the skiis for the first time she flew a bit tail heavy, and there is a bit more drag. I pulled the few oz of weights off the tail and will recheck CG. I didn't do a CG check before this flight, which I realize was a mistake I got away with. Clearly the tail ski is heavier than the tail wheel.

Also on my last flight I toggled the stabilization system with the mechanics gloves I fly with in the cold. I use the F-mode switch on my DX8-orig, right above the ignition kill switch, left side. My finger usually rests between the switches, but with the gloves I have to keep my finger below the kill switch. To toggle the stabilization system I simply slide my finger up (on) or lift it over the switch and pull it down (off). Yup. Killed the ignition mid turn in a tail wind 10 feet AGL. Landed fine but in the middle of footprints in the snow without any slowing (skiis remember) so she was still shooting across the ground and she eventually tipped. That snapped the ceramic top off the spark plug which hangs under the cylinder which hangs under the nose, which was probably quite brittle and cold, despite the engine heat.

I had tried not using a gasket on the muffler header. It sprayed post combustion oil all over the place aft of and around the header. Got some gasket material today and will cut a gasket for it today. Back when I replaced the cylinder I noticed that there isn't a gasket between the cylinder and the engine block... I wonder if that is where some or all of this oil is coming from?

Replaced the spark, made the "ski draggers", new gasket. Waaaaay too cold today with heavy snow, but maybe tomorrow we fly.

Monday, December 19, 2016

Big Stick Forward Wing Hardpoint Failure

It was frosty, 26 degrees, zero to 8 mph winds, but sunny. The snow was frozen on top but I thought I would still get out with the 10cc Stick on skis. I installed the large Du-Bro skis up front and a single Du-Bro park flier ski in back. Easy install, work fine. And slippery...

But the repaired forward wing hard point failed, fortunately on the ground. I need to come up with a way to firmly attach something to the wing to act as the cantilevered forward attachment to the fuse.

Hung the camera from my neck strap.

So disappointed that after getting my gear out to the field to not get to fly. At least this came off before lift off. That would have ended poorly. Trying to think of ways to fix this problem. I don't have much space under the wing, none in fact forward, as the fuel tank is right there. This limits bringing a long piece back aft for better leverage.

Friday, December 9, 2016

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?

Thursday, December 1, 2016

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.

Friday, November 25, 2016

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.

Thursday, November 24, 2016

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!