Cessna 172 Replica Production

[cjellwood]

well it is only a theory at this moment but I cant see why there should be any problems with it. I avoid mechanical engineering wherever possible so welcome the thought of simple rods and sensors like this. Here is a pic of how simple it should be i.e. a small box that contains the optical circuit and the rod being feed through the guide so it moves over the sensor camera.




Any size rod or tube can be used but in this case it is a handy 6.35mm rod (1/4"). Quite a catchy name too, "Optical Pot"

Chris

[No Longer Active]

The idea that you have described chris is exactly what I had thought of long ago, but not for a throttle, but for a flight yoke!

This would be perfect technology for a flight yoke!

[cjellwood]

Same here, an old thought for the yoke and the idea cropped up again for the throttles levers. Both x and y axis are detected by the optic so pretty much perfect for everything.

Imagine this... there is a button on the side of the opti-pot which you press. While it is pressed you push the rod through the range of movement you are measuring (both axis) and it records those parameters in the PIC's EEPROM. Now the opti-pot is configured to measure your exact distance range and output voltage accordingly. That would be complicated for when bi-direction is required such as with a yoke but definately possible.

Chris

[cjellwood]

The interface PCB is 99% complete, just missing a couple of optocoouplers.



Chris

[AK Mongo]

There is also the issue of FSX even responding correctly to minor screw adjustments as it would in a real plane? For teaching purposes a control system with screw function could be dangerously misleading if a student makes adjustements in a real plane according to how it reacted in FSX when turned. Given the sensitivity of the average potentiometer it would probably be a case of [7 turns in FSX = 2 turns in real cockpit] or like effect (if you know what I mean .

My setup works exactly like the real thing. Twisting on the verniers moves the prop and mixture handles in small increments, and translate into smaller movements on the linear pots. I am using 100mm slide pots, and there is slightly less movement than that in the handles, so I am "wasting" a few mm of the pots capacity. So far, the engine controls are the thing I am most happy with in my "pit", and the realism of pushing in the lock for gross adjustment, or twisting for finer has been a happy surprise.

[cjellwood]

Thanks for that info, the travel distance in general is something I am concerned about at the moment. Are you using original Cessna knobs? It would be great to know the travel distance for the original Cessna throttle, mix and prop knobs; something I forgot to measure when I had time inside a cockpit. The simkits controls look like they are using 60mm pots but that seems a little bit short.

The plan at this end is to reduce the controls cost by modifying cheap vernier controls that are available from China such as this one...



The stroke/travel available for these controls is 80mm but the 'control end' that connects to this and has the steel rod for connecting is available in 50, 75 and 100mm range. That means if I connect this to a 60mm pot then the 75mm range end will be required and will only travel 60mm due to the restriction of the pot travel. 100mm seems a bit too long but if the optical pot happens then the full 75mm travel can be used. Here is a pic of the Chinese vernier assembly that includes the control end which has a solid rod rather than cable which is handy. The length of the rod can be made longer but keeping the same travel distance.



oh and I took a gamble on ebay by purchasing a cheap £2 mouse in the hope that it contained the traditional optical sensors for hacking. It is not the exact chip I required because this has a single chip solution for data/usb but I think data can still be accessed via a couple of pins listed as
Pin Description
4 DM/DATA I/O USB D- / PS2 DATA
5 DP/CLK I/O USB D+ / PS2 CLK



Is there any such software that can read and display PS2 data?

Chris

[AK Mongo]

I can't remember exactly, but can get underneath the hood and measure if you need. All 3 were more than 80 mm but less than 100 in total travel.

Reid

[cjellwood]

I can't remember exactly, but can get underneath the hood and measure if you need. All 3 were more than 80 mm but less than 100 in total travel.

Reid

That would be great if you could do a measurement. The vernier control end is restricted to 75mm but it can be modified if needed.

Chris

[No Longer Active]

Does this help:

[cjellwood]

Does this help:

Superb! Thank You! It looks like the travel of the rod is around 80mm when the knob and nut is deducted, so the 75mm Chinese vernier will be fairly accurate

Chris