PulseXT, Electric Starter Issues, and the Stik Servo

Made the throttle servo swap on the PulseXT 60 with its RCGF-USA 20cc It's a powerful 20 kg torque servo, but it was less than $18 from Amazon. I put a ferro ring on the lead and it has a plastic servo arm, so it should be well isolated.  The FUTABA servo was an old piece of crap and had a bad wire. I hope this solves the mid-range twitchies.

I mentioned in the last post that I fried my electric starter. It should be more than capable of handling the compression of the 30cc gas engine, but these RCGF-USA engines are known for their hight compression. With the issues I was having trying to start the MX-Bach, I melted the plastic around the contact bushings. I also found the old parallel cable I had made was coming apart so I rebuilt one. I used the bar from a couple of Traxxas connectors and soldered the leads to them, used shrink tube to cover it. Works great with my new Hangar 9 starter!

I also changed out the wonky Hitec HS-435HB servo on the Stik's tight aileron. Rock solid. With that and isolating the ignition noise. Looking forward to getting her up in the air!

MX-Bach Update

Finished a lot of work on the MX-Bach.  Rebuilt the fuse, and as discussed earlier built  new set of hardpoints for the gear. I purposely isolated them from the more fragi\e framework of the fuse. 

I decided not to fylly replace the stringers and just repatched. I used some more sheet balsa than was there before.

I was bored so I did a lot of darts. It helps break up the wonky framework.

I used screws allowing me to open the fuse to access the landing gear hardpoints in the future.

I put shark teeth on becasue I could.

Because I was still bored I used reflective tape on the nose cone fully aware that it would peel off. The cone broke under the load of  burning out my Hanger 9 Electric Starter.

So the down side is that I spent hours today trying to get the RCGF-USA30cc started. It didn't matter how I tried to tune it, but it would only start really rich. I finally had to give up. I suspect another bad carb. When I did get it running she would seem fine, held WOT fine, but then started pulsing and then quit. I am working on getting another carb to try. Makes no sence, the carb looks fine.

Tray table upright and locked, and servo jiggles

Gorgeous day, out this morning just before noon to take the Stik and the PulseXT60 up.

Never a day when I just go out, set up, start an engine, fly a few times, pack pack up, home for a beer and a cigar.

The RCGF-USA 10cc engine ran fine. I had managed to shield the servos from the ignition noise. But in the meantime the right aileron servo fried and now locks up slowly and won't respond. No Fly For You! Ordered a new Hitec HS-485HB to match the other side, from Amazon Prime.

Tray table upright and locked...

But at least she ran well!

Flew the PulseXT60 , still not happy with the engine tuning. I took the cowl off and retuned her, got most of the mid-range 4-cycling out by leaning the high. Realized as I was watching her that when she is running the throttle servo jiggles in the mid-range. I think its a bad servo, several of the servos given to me when I bought the kit have failed and I think this one did to. I ordered a standard digital servo from Amazon Prime.

I do like to support my LHS, but one never quite knows what they have in stock, understandably they can only stock so much. Amazon Prime gets it here at a good price in two days. Capitalism sucks.

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!