Repairs on the MX-Bach

The carb bolt/reed block debacle aside, I got a lot done fixing the landing gear hard point and repairing the fuse.

I first made the hardpoint attachments that would sit on the side walls of the undercarriage, supported by the long  plywood attachments that would run most of the length of the sidewalls.

I used the old hardpoint to set the spacing.

It fit perfectly. I replaced the silver screws with cap bolts after epoxying it all together.

Everything set with 30 min epoxy and clamped in place.

I devised a way to use self-setting nuts and attache the gear directly to the metal hardpoints, removing the wood hard point altogether. I spent the rest of the day repairing the framing of the fuse.

Working on repairing some cracks in the temporary nose cone and repainting it. I am also painting the plate that the fuel vent is attached to. I will install it and close the cote.

Once everything is back to repaired, I will troubleshoot the engine and start all over.

How stupid am I?

Pretty damn stupid.

As a result of my deadstick landing kerfuffle, the engine compartment was full of dirt. I started the repairs today and cleaned out the compartment, and removed the engine to clean the carb, as the engine being covered in dirt, surely there is dirt in the carb. Unmounted, took the engine apart, setting aside the carb, the pulse/insulating compartment (that black thing with the hose in the pick), the reed valves and the engine block. Mental note of the orientation of the carb on the block, check. cleaned the carb, a little dirt, the engine block was fine, the reeds needed some cleaning. All is well. Reassemble.

Well, that's weird. I didn't notice that the insulating block had such gaps... and so I made a gasket, and screwed it all back together, but the carb bolts were too long, and the ends were in the engine block, stopping the crankshaft from running. Jeez... Well, let's cut those long ass bolts and reassemble it.

Why the hell do the bolts go so far into the engine block. Who designed this??

So I reassemble it, insulating block, reed valve (wait, what?), carb, but now the frickin' screws are too short. And I didn't even cut them the same size... 

Oh, for the love of all that's holy... I am so frickin' stupid. And that's putting it lightly. 

This was a cluster the moment I first put it back together. See, I left out the reed block the first time I put it back together... so of course the screws were too long. My first stupid was forgetting to install the reed block the first time. My second stupid not stopping to recognize the engine ran just fine without me cutting the bolts. My third stupid was cutting the bolts.  That was the unrecoverable stupid because I don't have replacement M5 - 60mm bolts. Now I have to wait for my order to arrive from RTL Fasteners.

So, that's how stupid I am. Well, I wanted to take a break from this plane anyway...

Family Photos

My wife took these from the back deck while I was working out of my basement workshop on setting up and running the RCGF-USA 10cc on my Ugly Stik. The wing is on so I could test the rogue aileron issue having also addressed the spark cable signal noise. This is such a nice plane!

New Carb, New Life, and Ignition Noise Ousted!

I have had issues with this RCGF-USA 10cc gas engine for several months after several years of great operation. I figured out there was something wrong with the old carb after a bit of screwing up the motor during a rebuild when I broke the piston ring and did something to the original carb that made it wonky. I replaced the piston ring, and I tried a smaller Walbro carb, I think 7 mm from the original 10mm as people argued the 10mm runs the smaller engine rich. I could not get the 7mm to run well. I bought a new 10mm stock carb from Joe Nelson at RCGF-USA and installed it today, and she ran well with minimal tuning. The high is a bit rich: mildly rough 4 cycling in the mid range and when pulled back from WOT she drops a bit lower in RPM then works her way up, but I tuned it as lean as she would allow and its mostly gone now. Runs great, will fly her in a couple of days.

John Hayes offered that my rogue ailerons at WOT was ignition noise. I pulled the ignition and the casing of the spark cord is frayed. It did not like being crammed into the forward compartment for all these years  Covered the frayed parts with electrical tape and shrink tubing, left the cable outside the compartment and voila, no problem!

7mm on the left, stock 10mm on the right.

I like that I can remove the throttle arm, which was short and a bit different than usual. I replaced it with an aluminum servo arm. This engine has a choke; the 7mm did not and was always a challenge to cold/dry start.

You can see the rubber cover is pulled away from the casing, and the wires of the cable frayed here, and a bit further down rubbed down a bit. I used thick shrink tube for the casing end and electrical tape for the middle fraying. The ignition noise is gone!

You can see I left the spark cable outside the compartment.

Underside view. You can see the choke arm and the throttle arm.

Another view of the choke and throttle.

Runs great, no ignition noise effecting the ailerons!

Can't wait to fly her day after tomorrow!

Baby learned a new trick...

I had a half day, and a bit later than I planned (lazy) I got out this morning with the MX-Bach. She started with the electric starter, and ran pretty well, though she had this stutter thing that I was pretty sure was just a little 4-cycling in a 2-stroke. But some of the pauses are pretty long and not a quick sputter.

I catch some of the 4-cycling behavior here, none of the solid pauses.

As she idled she initially seemed happy pre-flight, and out of the blue just stopped. Restarted, and she again ran fine throughout her range, ran her up and down a few times, every thing was fine. So I took her up, and she flew so incredibly fine, smooth like buttah, some light aerobatics, and running through her throttle range. Let her idle high up several times, sweet, no issues. Plenty of power. Ran her down the line at altitude WOT and suddenly nothing. It just quit. No slowing, stuttering, racing, just quit. So suddenly I would later wonder, "Did I hit the kill switch?" I trained myself so that when the engine does die after moment to ensure proper control (aviate-navigate-communicate) I instinctively hit the kill, so I don't know just when I actually did.

Sweet deadstick approach, landing a bit hot, touched down nicely but then bounced and...

Pleased with the approach and initial touchdown, but annoyed I let her bounce and ripped the gear out again. Lots of work to do. For now I am going to assume that this was a one off, and get the gear fixed, restart the engine after replacing the prop. Should I swap out the RCGF Ignition for new one I have on hand, or is this the Hall Sensor? Maybe I swap out the sensor first, least effort... If she just wasn't such a stable sweet and smooth flyer.

I noticed that only the right elevator moved when I set in some trim with the flaperons to give her a bit of nose down. Not sure why the left one didn't follow. Need to sort that out. Is it a mix? This wasn't a problem before...

Resetting the crash clock.

Hangar Day

I had to wait for the new DX8 Gen1 Antenna to arrive, and Amazon delivered it damn near next day. It arrived this afternoon and took me a couple of minutes to install. 

Once I had it installed, I took the MX-Bach outside and took Joe Nelson's (Owner RCGF-USA) advice and used my 12V electric starter to get the new 30cc engine to start. As he said it would, she started right up! Got her idle settled, I believe, so I am very, very happy about that. Was going to take her out to fly but someone said, "Lunch at the Beach Plum?", so that happened instead. 

When I got back I decided to fix the wonky and broke vertical stabilizer. on the Ugly Stik. That thing has taken a beating over the years.

I removed the vert stab, and if I had given it any thought whatsoever, I would have repaired the cote on it then, but no I did it the hard way, repairing it after I reinstalled it. Here I have removed the stab and drilled 4 holes for posts to help strengthen it.

I mirrored these on the bottom of the vert stab. Thought I had a pic of the posts... nope. I just used "match stick" wood.

I used 30 min epoxy to install it, and after a couple of hours, I epoxied in two runners, one on either side of the base of the vert stab to stiffen it, also using 30 min epoxy.

Re-coting the stab was not as easy as it could have been, but this thing has been repaired several times. The cote is quite a patchwork.

The "American" on this side interprets the German on the other, a play on  Shakespeare (see what I did there?).

In preparation for the new 10mm stock replacement carb I ordered from Joe, I removed the 7mm smaller carb I tried out. I don't know, maybe it would work fine, but I have had more trouble getting and keeping her running and tuned since putting the smaller carb on. The thought is that the 10mm carb is big for this size engine and tends to run it rich. That may be, but I think this small engine prefers to be rich because even when I had her tuned as well as I could, I could not get her not to stall out on pulling the throttle back quickly from WOT or half even if I slowed the servo speed. If I eased it back, she tolerated it. I am going to send that smaller carb to Joe to play with. It wasn't designed for RC aircraft, but he is good with this sort of thing and it may be better for the engine in the right hands.  Once the carb is in, I need to check out the ignition and maybe replace it to see if that is the cause of the ailerons going rogue, usually full RT roll, left full down, right full up in a spasm, then it returns to normal, just at WOT.  Is there a noise leak? It happens with the two receivers I tried so I know that's not the problem. The receiver is way back in the fuse. I need to research how to further shield it...

The Stik has been ridden hard since I got her back in July 2016. She has been my go to gasser, capable, stable and predictable, my Alpha 450 with power. Her engine has also been the most cantankerous... but I have learned a tremendous amount from her. Looking forward to getting her back to reliable flight status.

Well, this is good.

She starts and runs awesome! She stopped running in flight the other day and I could not get her to start. She has been very challenging to hand start. When I mentioned this to Joe Nelson of RCGF-USA he smiled (it was an email, but I know he thought ti funny I was working my wimpy biceps so hard) and suggested not trying to hand start her until a couple of gallons went through her. I put my 12V starter on and shaboom.! Right away, ENGINE NOISE!  Adjusted the idle, which I think lead to the deadstick, and she seems rather happy. Once she warms a bit and breaks in more, I expect to be able to lower the idle a tad more, she is just barely producing thrust at idle.

I did swap out the nice carbon fiber nose cone for the painted Ultimate Style one so I don't mar the nice one.

This motor tried to lift the back of the table off the ground! Some kinda power, and what a sweet sound!

Baby, Daddy's goin' flyin'!