« Posts tagged stick grips

Zero Sum

6 hours.

I spent a whole lot of yesterday doing various things, which is the surest way to feel like I got nothing done.   I had two goals: Fix the idle stumble and run down that AP engage joystick wire issue.

The first part was almost easy.   I set the mag timing to 25 degrees per the engine data plate.  I’m getting to be an old hand at setting mag timing.  I got them both firing in sync, then made the idle richer by a couple of flats of the adjustment linkage, per the AFP manual.  Sure enough, that cured the off-idle stumble and my CHT’s and EGTs dropped noticeably.  But there was still a rough idle, so more adjustment needed to happen.

The manual says that adjusting the idle is done with the engine running.  The problem with that is twofold: One, working near a spinning prop scares the crap out of me.  I haven’t had the training to do so safely.  Two, because of the orientation of the throttle body, the idle linkage is on top, between the throttle body and the engine case, and the only way to get at it is by reaching past hot exhaust pipes.  Even if I did have the stones to crawl under there with the prop spinning, I can just see burning my forearm on the #1 pipe and yanking it back into the arc of the prop.  No thanks.  I did my idle adjustments with the engine off.

With Mike as the casual observer, it appeared that my idle was too rich, because there was a bit of smoke coming from the pipes when I was idling and the idle was definitely a bit rough.   This is caused by multiple symptoms, but a too-rich mixture is the first and most obvious culprit.

The manual also says that the best way to adjust the idle is to leave one of the jam nuts “just snug” and turn the block one flat at a time.   Well, yours truly interpreted “just snug” as “don’t touch” and after a couple of turns of the block, the left-hand rod end bearing snapped off at the jam nut.


So now I have to find/buy a LH thread #3 rod end bearing and I can get back to business.

As for the other stuff, I did chase down the AP engage wire.   Turns out I have to figure out a way to do some kind of voltage differential and use the MGL script editor in order to remote-control the EFIS to engage the autopilot.   A simple “Hey, I’m Grounded” won’t work.   This will take a minute to work out the logic, but I’ll email Matt at MGL and see what he says.

Also, Owen and Ron got the racing scales, so I can do weight and balance.    This gets done first thing today, because I need to return the scales ASAP.   It’s   I’m just hoping the W/B comes in as expected.

I also fiddled about with the wheel pants, but that’s not high on the priority list right now.

Panel v2.0

1 hour.

Redesign of the panel based on some thinking and some comments and suggestions from VAF. Notable changes: Master and alt bus feed are now to the right of the EFIS, putting all the DC power stuff there, safely out of the way of casual bumping. The second is the addition of a start button, eschewing the spring-loaded dual-pole ignition switches in favor of dual-pole on-on switches per the Aeroelectric Connection. The start button will actually be on the Infinity stick grip, but if that wire snaps somehow, I want a way to start the plane. Another significant feature is the addition of the Pax Enable switch, which disables the buttons on the passenger side stick grip and also safeties the connector when the stick is disconnected. There’s no starter enable switch because there’s very little chance of me bumping the starter button in flight. It takes an actual effort to depress the Infinity switches, so I don’t think the risk of accidental starter engagement is enough to merit the complexity of another switch. I guess I could wire an off-on-(momentary on) toggle in place of the start button that would serve the same function, but it puts an extra step in the checklist (disable start) that I don’t think is necessary. Also, in case of an engine out, I want as few things between me and the starter as possible. Phones and Mic have been moved to the lowest point possible on the panel, but i’m not going to put them in the armrest. Eventually I’d like to get the Classic Aero interior, which would cover up any accessible jacks in the armrest. There will also be a wet compass mounted on the glareshield or in the panel, I haven’t decided. Ideally, I’d keep that million dollar view free of obstruction , but I’m concerned about interference from wiring. Also, the buttons have been moved to the top, so that nothing gets shut off or bumped during turbulence, and the transponder has been moved to the bottom of the stack.

Click to open full size.

More grip stuff

1 hour.

I finished changing out the on-off switches and toggle on the other Infinity stick grip. Now both grips will have the same configuration.

stick grip soldering

And this is what the finished product should look like:
grip on stick

grip on stick
Tested for ergonomics. This works just fine.

But there’s a problem. Remember that big fat blue cable in the first pic? There’s no good way to get it out the bottom of the stick, and on the right side, it’s pretty much impossible. I may have bitten off a fair bit of work for myself here, but I need to find a solution. One thing is for certain, and even though a lot of guys have done it, Van’s says “Thou shalt not drill holes in thy control stick, especially near the holy pivot.” The reason for this is that with a hole drilled in the stick, the yield strength of the tubing has just gone down the crapper. You can argue all you want about the likelihood of someone putting enough force on that stick to break it off at the hole, but I’d hate to be doing a high -g (for me anyway) maneuver and have the stick fold up.

So what to do about that fat blue cable? I have two issues, one is the exit out the bottom of the left stick. The cable chafes on the rod bearings connected to the ailerons, so that’s no good. The other is that on the right side, the stick is designed to be detachable, and it’s going to be, because the missus likes to knit and read books, and she’s not going to have a good time doing that if there’s a control stick waggling where she’s holding a book or a big-ass pair of needles.

In that blue cable are sixteen 20AWG wires, six of which are ground wires (earths, for my Commonwealth readers). I have read of several builders who have stripped off the blue outer cover and the shield, then connected all the grounds together in the upper cavity of the grip, which thins out the wire bundle considerably. This will allow the wires to exit the bottom of the control stick on the pilot’s side. On the passenger’s side, there’s no getting around it, there’s going to be a hole drilled in the stick for wires to exit, but not the honking 5/8″ monster required for the full cable, blue covering and all. That will also require some kind of multi-pin connector, such as a CPC circular connector or a DB-15, so I can detach the stick easily. It’s already sounding like a lot of work, but fortunately it’s not a messy job, and I can start/stop it at leisure.