YF-22 vs YF-23

Anything goes, as long as it is about the Lockheed Martin F-22 Raptor
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wooster

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Unread post31 Jul 2019, 01:44

f119doctor wrote:One of the complications on the YF-23 all Flying V Tail surfaces was the actuators needed for these large control surfaces. The solution was a stepped piston actuator. Only the smaller inner diameter was used at slow speeds where the dynamic loads were low and large / fast tail movement was necessary. At high speed where high force was needed to move the tail surfaces, the actuator shifted to use the larger diameter of the stepped piston. The smaller surface deflections at high speed allowed the limited flow capacity hydraulic pumps to keep up in this high force / large piston condition. A hydraulic system flow capacity increase (pump sizes, line diameters, coolers, heat rejection, etc) had unacceptable trade offs to use a single large diameter actuator for both conditions.

One of the Northrop flight control challenges was to manage the shift of the actuator from the large deflection mode to the high force mode as the aircraft acellerated and maintain acceptable handling characteristics during the shift. I believe that they were mostly successful, although the test pilots did report that the shift point was noticeable.


Wow, great write up. Never heard of that before. It just shows how much ingenious thought went into making it stealthier and the weight that Northrop put into stealth. I can't believe they publicized that system to the white world. How does that differ from say the tail surfaces of the B1 which are also large and the bone flies subsonic and supersonic and is quite good at maneuvering.
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madrat

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Unread post31 Jul 2019, 02:14

The Bone has much more capacity to power actuators and doesn't require such high performance adjustments.
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