5 ms·
This makes more sense, thanks. I still don't understand why the trim is "stronger" on these planes than a fully pulled back column. Is this necessary on large
by keyme 8y ago
This makes more sense, thanks.
I still don't understand why the trim is "stronger" on these planes than a fully pulled back column. Is this necessary on large planes?
- weaksauce 8y agoprobably mostly due to needing to have a larger operation margin for different center of gravity as load changes depending on the current flight passenger/cargo loadout.
- ncallaway 8y agoMentour Pilot (as others have mentioned in various other comments) does a great job explaining this. On the 737 the trim adjusts the entire rear stabilizer (the entire horizontal structure of the tail), while the elevator is a sub-component of that stabilizer. So, when you adjust the trim, it's a much larger surface area that is moving. Ultimately, the stabilizer just has more aerodynamic control that the elevator, due to the larger surface area. I have no idea why the design is that way, though.
- inferiorhuman 8y agoI have no idea why the design is that way, though. Cost, maintenance, weight, etc., probably. The only jet airliner I can think of that uses an "all-flying tail" is the Lockheed L-1011. Nearly every other plane you'd be riding on will have a big stabilizer and a smaller elevator.
- phire 8y agoRedundancy too. If both redundant hydraulic systems to the elevator fail, or the elevator gets stuck for other reasons, the emergency procedure is to control pitch with just the stablizer trim alone.
- inferiorhuman 8y agoPresumably you could have a redundant drive system for the combined stabilizer/elevator. The L-1011, for instance, had a safety record Boeing should be envious of.
- WalterBright 8y agoOne reason is to recover from "mach tuck": https://en.wikipedia.org/wiki/Mach_tuck#Design_features https://en.wikipedia.org/wiki/Mach_tuck#Design_features