Best way to mechanically achieve automated thrust levers?

[AnglaisEnUzes]

Hi guys,

I have been thinking about the best way to achieve automated throttles in the most space efficient manner.

I have an audio and music background, and it occured to me that rather than using a potentiometer AND a servo, would it not be better to use something like a motorised fader, as found on mixing consoles? The Penny & Giles range is popular in the audio world.

This would achieve a) the sensing of position and b) a mechanism to provide movement back to the lever, as well as c) being in linear form (which would be useful for situations where more than 2 levers were used).

A method for converting linear to rotary would have to be devised, but that would be relatively simple to achieve.

Have these ever been used by anyone? Are there any major drawbacks I am missing?

Thanks!

Martin

[Westozy]

Audio faders are generally logarithmic and not linear. It's better to have linear pots on FS throttles or you might end up with a lever that gives say 0-20% N1 at the halfway mark and 20-100% N1 in the second half of the lever movement - something to consider!

Gwyn

[Michael Carter]

In addition to what Gwyn said, and audio servos or pot motors would probably not provide enough torque unless you used enough gearing to move the weight and friction of the throttles.

[AnglaisEnUzes]

Thanks guys - I was aware of the linear vs log scales (Penny and Giles make a range of linear pots) but had not thought about the torque issue.

On almost the same subject, I have been considering how to best make the reverse thrust levers work. I have the Boeing 777 Training Manual, which has some fantastic cutaways of the quadrant system, and it appears that the RT levers are mechanically connected via rods to the TLA resolvers.

My feeling is that this could be "got around" by using miniature linear pots *in* the throttle assembly (ie, as the first connecting rod). One can, for a reasonable price, get mini linear pots around 80mm retracted, which should work nicely. I'm going to do some drawings to see if it really is viable.

Cheers!

Martin

[yoss]

Well, i did just that

Used the 50k motorized pots from audio equiptment--they consists pot, dcmotor, gear and clutch all in one package
As a interface the open cockpit dc card is used

As the torgue is low--counterweights to compensate the weight of throttle assembly was added below

Adding her a link where you may see some photos of my creation
Thats Israel pit builders site, so ignore the language :)

http://www.vatil.org/vatil/board/viewtopic.php?t=13228

[AnglaisEnUzes]

So it has been done...

I think I might go with it - I am building a "scale" replica of the throttles to go with a "scale" set of controls in a custom setup - I am not looking for 100% accuracy to the original, and I want to keep it as light as possible, so maybe the lack of torque won't be too much of a problem.

There are 2 things that are causing me grief:

First is the reverse levers. I would like to keep them as part of the main thrust levers (as on a "real" setup), but it is quite tricky mechanically. I think the mini linear pots might be the way to go (the whole reverse mechanism is then attached to the main levers, and moves with the levers.

Second, is detents. I have no idea how to create them. Flaps detents are easy, as the "mechanism" is on the outside of the quadrant. As for the thrust detents, I'm stumped!

I think TOGA and ATHR Cancel buttons will go onto my rig as separate items - not ingegrated in the levers (unless I can think of a clever way to do it easily :) )

Cheers!

Martin

[AnglaisEnUzes]

Looks interesting:

http://www.specsensors.com/pr/readproducts.asp?newsID=251

[yoss]

Looks interesting:

http://www.specsensors.com/pr/readproducts.asp?newsID=251

Yes it is, but seems to me-this device is very small

That what i use:


http://cgi.ebay.com/ALPS-705t-25K-RD296301-Pots-Potentiometer-Motorized_W0QQitemZ290207623079QQihZ019QQcategoryZ58164QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

As to reversers--i use microswithes
TOGA and ATHR Cancel buttons are another simple pusbuttons assighnet
via Fsuipc--no probs with them

Few advises if you will deside to go this way:

Keep the mechanic balansed , adding counterweight --i mean throttle levers and handles assembly -- that most important
Alsow do them as light as possible

Regards

[737NUT]

I just posted the PERFECT solution to utilizing true reverse thrust movement and nice linear travel. STRING-pots! I will NEVER use another slide pot or rotary style pot again! They may be 8-10x's the price but you get what you pay for, headache, sloppy and inconsistent set-ups when not using string pots. Just my .02

[AnglaisEnUzes]

I just posted the PERFECT solution to utilizing true reverse thrust movement and nice linear travel. STRING-pots! I will NEVER use another slide pot or rotary style pot again! They may be 8-10x's the price but you get what you pay for, headache, sloppy and inconsistent set-ups when not using string pots. Just my .02

Thanks. That's an interesting concept - how is the "springback" on the strings? It it workable?

I have decided to start with the 737 quadrant on http://www.737ngproject.be/ and add to it (motorised throttles, pot based reversers etc).

Then, when I have built it and it is all working, I will work on a 4-engine variant of it.

That way, I will have separate 2 and 4 engine quadrants, and I can learn from an already working "base", rather than designing from scratch!

Cheers!


Edit: The quadrant looks reasonably simple to convert to motorised, if motors rather than servos were used. Take this image:

http://www.737ngproject.be/images/Montage/IMG_1329.jpg

If one "extended" the throttle plaques and external plaques downwards (you cannot extend *all* the plaques because then there would be no room for the motors), you could fit a gearing system and a miniature high torque motor such as the V963 from Astrosyn. As long as the control logic was carefully calibrated, then that would be reasonably simple to do (simple being a relative concept here ;) )

Martin

[737NUT]

The return spring doesn't cause any issues for me and is flawlessly working. :)

[AnglaisEnUzes]

Ok excellent I'll look more into it.

Back to motorising throttles - one option would be to use a giant scale servo which is converted for continuous operation. If geared that would provide very high torque...

How quickly to 737 levers move?

M

[737NUT]

Ok excellent I'll look more into it.

Back to motorising throttles - one option would be to use a giant scale servo which is converted for continuous operation. If geared that would provide very high torque...

How quickly to 737 levers move?

M

On my old 737 sim, i used Hitec 805's which when not powered, you could easily move them even while connected. No need for a clutch mecanism. As for torque, it would toss my throttle arms around in the real TQ i had like plastic toys!

[AnglaisEnUzes]

On my old 737 sim, i used Hitec 805's which when not powered, you could easily move them even while connected. No need for a clutch mecanism. As for torque, it would toss my throttle arms around in the real TQ i had like plastic toys!

Did you have to convert to continuous action or was it enough just to use the servo as is, with no gearing?

Cheers,

M

[737NUT]

No gearing at all. I had them connected via a 4-40 threaded rod and r/c airplane heavy duty clevis using the large arm that came with the servo. I used 6volts and those servo's have over 400oz of TQ!