burning question - HSI?

[AndyT]

Obviously you are way better at this 3D thing than I am.
Very nice idea.

Scott, I'm not sure about that, but you could be right.

[ruprecht]

pointers are diven by some type of differential gearing rather than being driven by independant motors. So one motor drives all three at once and the differential gearing just sets the relative positions of the course pointer and heading bug.

That may well be the case mate, but we'll need a smarter head than mine to figure out how to build that! I was right with you up until the word "differential"

[cscotthendry]

I've been thinking about the gearing. It'll come, it just needs some cooking time.

[Westozy]

Ruprecht:

I intend building an HSI for my sim when the time comes. I'm planning to build the BK KI525(a?). I have a couple of plastic copies of the face for the artificial horizon in this series and plan to modify that for the 525 face. I need to work out the mechanics of it yet. If you want to PM me maybe we could collaborate on the design.

Err... Ruprecht, I see you're in sunny Brissy. Where are you? I'm on Russell Island.

Hi Scott,

My friends Joe and Nerina have bought a property on Russell Island and they own "Russell Island scoota cars". They are Perth based but will be living there after Christmas.

Gwyn

[cscotthendry]

Gwyn

I don't know them personally, but I know of them. Some friends of mine who own the island restaraunt know them. Six degrees of separation eh?

[Westozy]

Gwyn

I don't know them personally, but I know of them. Some friends of mine who own the island restaraunt know them. Six degrees of separation eh?

Rgr that, Nerina has been singing at the restaurant, she is currently my partner in music! I will no doubt be visiting Russell Island at some stage in the future.
I see you are a machinist capable of producing gears, I am also a machinist but only have a lathe. I have been trying to locate stock plastic gears to suit my Airbus TQs without success, would you be interested in a job producing a few for me? I want to use gears to drive the pots instead of the current drive system I am using. I'm also thinking of changing the trim indicator drive chain. Cash or trade services, no probs! I'll PM my phone # for a yak if that's ok.

Looking forward to your reply,

Regards,

Gwyn

[ruprecht]

I've bought gears from Serv-o-link in the US as recommended by Mike Powell's book. It's obviously not the cheapest way to get gears, but they come in a good range of sizes if plastic will work for your application.
Do any aussies know what tooth pitch/PA the Jaycar gears are?

[ruprecht]

A little more design work this evening:



Might do some more after dinner. That is based on the dimensions of a servo I had to hand, which is unbranded, though it is roughly the same size as the Futaba S3107 micro. The CDI needle sticks out about 6mm to give full travel; to reduce parallax you could mount the servo farther back from the CDI plate. It's too late for the maths right now

When the model's a bit more advanced, I'll publish an animation showing how it all works.

[AndyT]

Thats nice. The problem is the servo must be further back so the From/To indicator can fit in there. It could be a couple of LEDs with a servo switch somewhere else in the housing. You will need your first set of brushes for this. To help you visualize this, add the wires to each servo, (or LED).

Also, the servo you are showing has to be attached or at least move with the inner CDI plate that will have the arrowhead on it. That whole assembly needs to be able to spin 360. This is where your second set of brushes is going to come in.

And since you are so good with the 3D modelling, how about if I forget about making mine and just comment on yours? (It's not as easy as it looks ya know... )

Why 4 outside gears for each ring?

[ruprecht]

the servo must be further back so the From/To indicator can fit in there.

Yup that's not hard to do, the design is in my head. Or you could move the TO/FROM indicator slightly outwards from their usual position - I will cut holes in the CDI plate later to show you what I mean.

It could be a couple of LEDs

Great idea, I was thinking a solenoid, but LEDs are much simpler.

with a servo switch somewhere else in the housing. You will need your first set of brushes for this. To help you visualize this, add the wires to each servo, (or LED). Also, the servo you are showing has to be attached or at least move with the inner CDI plate that will have the arrowhead on it. That whole assembly needs to be able to spin 360. This is where your second set of brushes is going to come in.

Spot on - my thought is to actually have microcontroller-driven circuit mounted on the back of the servo/CDI assembly, so only 5 wires are needed through a brush contact arm, and it can drive the servo, TO/FROM indicator and off flag all from one device.

Why 4 outside gears for each ring?

Just supports for the main gear assemblies. Probably overkill, but with the close tolerances on the HDG BUG and RMI flags, you wouldn't want too much wobble. They should be able to rotate independently of the two other support gears on the same axis.