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-   -   RV-3B Dave's in Colorado (https://vansairforce.net/community/showthread.php?t=85658)

David Paule 03-21-2021 08:18 PM

The steps are made but so far are unprimed. Since the spar bulkheadís flange is truncated compared to what drawing 24 shows, I added a J stiffener to that area of the step. And since the joint to the seat pan also felt less than stiff enough, I put one there, too.





If you look closely you can see that initially I drilled the steps for a nutplate that belongs on a mating flange. Iím in the middle of adding the new nutplates needed, and have some screws on order.

Incidentally, Russell made his steps .063. Mine are .025. I dropped something on the left one and it put a small ding in the step. Thereís probably a happy middle thickness, but it might include not dropping stuff on it, too.

After the steps, it was time to start mounting the avionics shelf. But before that, I tried to mount the rudder and brake pedals. After moving them to a position that felt about right, I discovered that I needed more hardware. Oh, boy, two jobs in a row needing more hardware.

Moving right along to the avionics shelf, it seemed like a great time to attempt to mount it. So far I havenít needed more hardware, donít know how this one slipped by. The fore-aft position is still a little bit TBD but since thereís only about 3/8Ē available to adjust it with, itís practically there. The next thing I found was that it wasnít quite as stiff as Iíd like. First I added a layer of carbon to it, with a layer of glass on that, and that helped.

A larger improvement came with a small change to the mounting arrangement. This also pointed me to a convenient place to bring the belly wiring up to the shelf, another good thing to figure out. Those wires will come out the top of the spar bulkhead pair on the right side.

Two little brackets as yet unfinished will hold the aft end of the shelf. The forward end is semi-TBD; I've got some ideas but nothing final.

I started reassessing the position of the components yet again. Hereís one version with the EarthX 900VNT battery on the shelf.



The 900VNT is overkill for my O-320 with its 40 amp alternator but itís the only 12 V battery they make thatís vented, and I won't put an unvemted on in the cockpit.

This post told me that the 680C fits in the cowl cheek and I verified that. John put it in the cowl cheek on his RV-4 but it also fits in the cowl cheek extension aft of the firewall on an RV-3B, and I might put it there. It would be very convenient except for needing a hatch. Hereís the shelf layout for that case.



In either case, the EMS will go on to the aft face of the firewall recess, which is convenient and thereís plenty of room for the cables.

You might notice that the last layout has the main power components on the right side instead of the left. That shortens the cables, with the battery in the right hand cheek extension.

Iíve been amusing myself trying to decide what goes on the switch panel. The switch panel is integral to the shelf but isn't really visible in these photos. The only thing Iím certain about is that this is a small airplane.

Dave

RussellT 03-22-2021 06:56 AM

Steps
 
Good move on making the steps with 025, I have found that when entering and exiting the cockpit I am stepping onto the seat and not the "steps". Mine (as I built them) are quite heavy and I subsequently drilled lots of lightening holes in the angle pieces.
It's looking good Dave, very neat.

David Paule 03-23-2021 07:49 PM

This is a mock-up of the switch panel thatís under the instrument panel. The real one is integral with the avionics shelf and I didnít want to drill holes in it until I was sure of the positions. This is the first pass at this, revision 0, and I'm sure glad I did this rather than committing to the real thing.



The two dowel pieces are the prop and mixture controls, both verniers.

From left tonight, the items are:

Prop vernier
Start
Mixture vernier
Master Battery/Alternator
LH ignition
RH ignition
Fuel pump
Nav/Strobe lights
Landing lights
Autopilot disconnect pushbutton
Autopilot servo power
LH Pmag breaker
RH Pmag breaker

The few warning lights will be on the instrument panel.

Still to be figured out -

Cabin heat
Carb heat
Carb ice detector switch
Carb ice detector adjustment knob
Alternator breaker

Ok, now to the question - since itís in place, no doubt Iíve had a chance to sit in the cockpit and give it a try. How did it work out?

Well, not so great. The verniers are in the way of getting into the plane or egressing. They need to move either to a quadrant or to the left spar bulkhead side.

The start switch, and itís a very nice start switch indeed, Stein sells these, is not bad but moving it to the left would be an improvement.

The four core switches in the middle are well-located one to another. But Iíd rather that they moved to the left, too.

The autopilot disconnect pushbutton, that red thing near the right, is right in front of my right knee. I donít think Iíd bump it accidentally but it would be better situated either in the middle or on the right side.

The remaining switches are fine and their position isn't that critical, at least in this version of the design. Well, there is this one thingÖ. Right now there are no labels and I had thought that Iíd be able to easily tell from the switch position whether it was on or off. Several of the switches have a middle position and frankly, itís not easy for me to look at these and tell what switch position Iíve selected. This was an unexpected and unwelcome surprise; I'm beginning to understand why people install fuel pump on lights. The labels will help, I expect, as will more experience with these. We'll see.

The fore-aft and vertical positions of the panel are entirely satisfactory.

Quite clearly I have a redesign and some rethinking ahead of me.

Dave

FinnFlyer 03-24-2021 07:48 AM

Stick clearance?

David Paule 03-24-2021 06:40 PM

Finn, thereís plenty of stick clearance, and although I checked that before committing to this avionics shelf/switch panel system, it was definitely worth double-checking now. I didnít measure it but it appeared as if thereís at least 1.5Ē, and the actual flight avionics shelf is shown in place. The stick is balancing in the closest postion to the switch panel.



The tennis ball is my idea of a decent stick grip. You can hold it and get a good grip on it in any direction. It never feels cold to the touch and it doesnít weigh much. Best of all, it has zero switches. A solid plus all around.

My dog Sawyer, whoís no longer with us, spent years teaching me the advantages of a tennis ball. Here he is in mid-lesson.



He took his tennis balls seriously. After he passed I counted about three dozen scattered around the house. The one on the stick is a brand new one, though.

This position of the prop and mixture verniers, over on the left, looks like itíll work out pretty well. But not.

After I took the photo, I sat in the cockpit and found that I needed to move the verniers closer to the inboard edge there, and considerably further down. Hand clearance drove them inboard and throttle clearance drove them down.

One thing I'm wondering about is the relative position of the prop and mixture control. As shown, the prop is above the mixture. Here in Colorado I'm more likely to set the prop and then leave it alone, I think, while the mixture will need adjusting more often. Any thoughts?

I havenít reinstalled the flap control handle but obviously thatís coming up soon.

Dave

PaulvS 03-24-2021 08:16 PM

thoughts
 
Dave,
I like the idea of the tennis ball, if it was luminous then that could also help with night time ops.

Here are some other ideas to consider, depending on how far the re-thinking is going to go:

The clock in the middle is taking up prime space and could be re-located to a wrist, or eliminated since the Dynon has built-in clocks and timers. An efis timer can be used to prompt switching fuel tanks. The efis and ipad could then be moved more to the centre and up, freeing up space along the bottom of the panel for engine controls. This may solve the positioning and convenience of the throttle and prop verniers.

I'm curious about the need for an analog airspeed, but not an altimeter? Is it intended for backup, or just personal preference for round gauges? I like round gauges too.

And assuming you must want to fly right-handed, rather than relocate the engine controls opposite to the side where you get in?

David Paule 03-25-2021 10:24 AM

The airspeed indicator is simply because I am trying to preserve the operational similarity to my C180, which not only has one but has the same maximum flap speed. Also it's a back up if the wee little electrons get lost.

I believe I have enough experience to be able to estimate my altitude well enough to stay safe for the day VFR flying I do. Good enough to fly a pattern, anyway. I don't think I need a round altimeter.

The clock is to easily tell me which tank I need to be on - whichever side the minute hand is on, that's the tank I need to be on. And if I forget whether I've switched a tank, it doesn't matter, just follow the minute hand. Since I fly the C180 set on both tanks, tank switching will be a new thing for me. I wanted an assist. That led to it being both clear and obvious.

The com radio cut-out fell off of the panel. It goes in that bottom gap in the middle.

Yes, I fly right hand on a stick when I fly a stick plane. Left hand on the stick feels unnatural.

I'm old enough that I want the plane to fit my own idiosyncrasies as much as I can.

Dave

David Paule 04-01-2021 07:24 PM

Here’s the next revision of the switch panel This one works fine - it’s what I’ll do for the real one. Left to right,

Start
Master Battery/Alternator LH ignition
RH ignition
Fuel pump
Nav/Strobe lights
Landing lights
Autopilot disconnect pushbutton Autopilot servo power
Cabin heat
Carburetor ice detector sensitivity
Carburetor ice detector off/on
LH Pmag breaker
RH Pmag breaker



The carburetor ice detector warning light will go up on the panel somewhere. I thought of putting it in that space to the left of the two breakers, which would be similar to the position it’s in for my C180, but honestly, that wasn’t something I wanted to duplicate.

I’ll decide where the carb heat control will go after I figure out the side panels or at least get a hack at them.

The two verniers seem to be home right now. In case you’re wondering how I put them on, I put a flush screw in the back of the dowel pieces (the forward end) and then put magnets in the bulkhead. This let me move them around and play with them.

Flashing back a little to the mold for the canopy fairing… I learned that instead of covering it with plastic and tape, I would have been better off covering it with heat-shrink plastic film, like the kind used on windows for extra insulation. It would have given me a smoother, tighter surface. Oh, well. I learned that from Jim Marske’s excellent “Composite Design Manual.”

Back to the avionics shelf with its switch panel now.

The forward end of the shelf is hung from the upper longerons with a couple of fittings. The first step in this was to glue the fittings to the shelf’s forward face. The photo shows the shelf upside down on my work bench.



Then I laminated some glass to the fitting and the face. The shelf is still upside down in the photo.



The glass will get one screw to each aluminum angle at the outboard end of the glass to aluminum joint to ensure that the glass doesn’t separate at the bond where it’s most highly loaded.

While that was curing, I made a throttle lever. The holes can potentially give several options for getting the gearing correct. The second hole down matches the lever throw with the carburetor throttle lever travel.



The green handle is, if I remember correctly, from an antihistamine container. It’s light and stiff and the feel isn’t bad. I
Drilled it for the push-to-talk switch and tried it out - seems to be satisfactory. I also soldered the leads to the PTT switch. That one is from Steinair like the excellent start switch, but doesn’t have nearly as good feel. Like the AP disconnect button, there’s little feel to it. I've got an Otto P7-5 on order for a replacement, per Mike W's recommendation from a thread in the Electrical section.

The handle will be held on with a couple of blind rivets, unless I change handles. I don’t care for the gun handles and whatever turns up would have to beat this one. And if you're thinking, "hmmm, tennis ball stick grip, medicine bottle cap for the throttle, is he going to use a beer bottle cap for the carb heat or cabin heat?"

I doubt it.

Dave

Walt 04-05-2021 07:31 AM

How tall are you? Small cockpit with extended panel = for short folks only.

RWoodard 04-05-2021 08:16 AM

Quote:

Originally Posted by Walt (Post 1515659)
How tall are you? Small cockpit with extended panel = for short folks only.

Looking at where the longerons pass through the panel as a reference, it isn’t much of a panel extension. My RV3 panel has a bit of an extension near the middle and I’m betting I could take at least a 3 inch extension across the entire width without inhibiting ingress/egress. I’m 5’10” and of normal proportions these days.

I definitely agree that it’s something to be mindful of. My Glasair has an extended panel and it’s barely acceptable to me and my 6’ tall brother really struggles. I’m going to be cutting 1-1/2” off the bottom for my new panel.


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