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Landing Gear Mechanism Case Study: F-5/T-38

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Radicaldude1234

Well-Known Member
Joined
May 30, 2009
Messages
430
Location
Front Range, Colorado
Hey guys! Got a little bored last night, did a little reading, and decided to whip up the mechanism on the F-5/T-38.

For those who don't know, the T-38 (and it's F-5 descendant) has really really thin wings. Not quite F-104 thin, but the maximum thickness where the gear mechanism is is just over 5 inches thick. I've always wondered how they fit the mechanism in there...

So I was reading this report: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19800016824.pdf

And ran across this picture:
Screenshot 2016-03-03 19.09.04.jpg

and this video:



With which I made this drawing:

Screenshot 2016-03-03 19.16.46.jpg

And created this assembly
AnnotatedConcept.jpg

Animated



Some observations:

1. The hydraulic actuator that the main gear has would need to be <4 inches to fit into the wing. Assuming the internal piston is 3" in diameter and given that the T-38's utility hydraulic pressure is at 3000psi, that would give over 21000 pounds of force to actuate the gear.

2. The mechanism uses it's braces with over-center locks as a down lock. There is no separate lock to keep the gear from folding.

3. There is a separate up lock that is normally operated by hydraulics. If the hydraulic lock fails to release, as per the T-38 Dash 1 there is a separate handle connected by wire in the cockpit to release the gear. The gear will then lower on its own and can be assisted by the time honored "Rock it to lock it" technique to lock it into place.

Will try to figure out how the nose gear works.

Thoughts?
 
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