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How trim works in Vega

Posted: 28 Aug 2018, 17:51
by Jarek
This is quite interesting mechanism, so I decided to describe it in details in the separate thread.
Ok, so first picture shows something that I didn't pay attention to. Please notice 10 vertical metal bars
attached to fuselage, they mark horizontal stabilizer movement area. It moves together with fairings that attached to it.
There is a little space between fuselage and this fairing. Rotation axis is located near the elevator hinges.
trim_marks.jpg
trim_marks.jpg (82.95 KiB) Viewed 240 times
So let's remove these fairings and look what's inside (thanks to Caroline):
caroline.jpg
caroline.jpg (45.33 KiB) Viewed 240 times
All pictures by famous John Oder. His webpage www.aeromuseumservices.com is not available anymore, so I decided to post these pictures here to save this information for others.

Re: How trim works in Vega

Posted: 28 Aug 2018, 17:54
by Jarek
Elevator in neutral position:
trim1.jpg
trim1.jpg (28.49 KiB) Viewed 239 times
Elevator in Full Nose UP position:
trim2.jpg
trim2.jpg (45.2 KiB) Viewed 239 times

Re: How trim works in Vega

Posted: 28 Aug 2018, 17:56
by Jarek
Rack and pinion type gear which moves front section of stabilizer up and down:
trim3.jpg
trim3.jpg (173.3 KiB) Viewed 239 times
Gearbox in the rear section of fuselage with control rod:
trim4.jpg
trim4.jpg (170 KiB) Viewed 239 times

Re: How trim works in Vega

Posted: 28 Aug 2018, 17:59
by Jarek
Gear box with the crank located in the cockpit (Lockheed Orion). Attached by 4 crown nuts, secured with cotters.
trim13.png
trim13.png (195.18 KiB) Viewed 239 times
This mechanism used in Vega is now called Trimmable Horizontal Stabilizer (THS) and was used on many modern airliner's designs, including Boeing 777 and Embraer ERJ.

Video showing it's operation in Boeing is available here:
phpBB [media]

Re: How trim works in Vega

Posted: 29 Aug 2018, 07:39
by Vitus
That's a great find! I didn't see those close-up pictures of the elevator trim before. But I am glad I got this part right in the add-on ;)

I guess the only inaccuracy is the missing torque-shaft. Dang.... I really liked the animated cables in the current version :mrgreen: