How can the F-16 remain stable when there is a loss of hydraulic power?

Edit for justification:

This question is different from If the EPU (Emergency Power Unit) on a modern fighter jet fails, will the aircraft drop out of the sky? for the following reasons:

The question in If the EPU (Emergency Power Unit) on a modern fighter jet fails, will the aircraft drop out of the sky? asks if an aircraft drops out of the sky if the EPU (Emergency Power Unit) fails, for a generic aircraft. The accepted answer only briefly touches on the F-16, and certainly not in a way to answer this question. This question is specifically about an aircraft with RSS (Relaxed Static Stability), and how this relates to loss of hydraulics and power.

Question:

The F-16 has Relaxed Static Stability (RSS) to enable a high degree of maneuverability.

This causes the aircraft to be inherently unstable and RSS is corrected for by the on-board computer in real time, as part of the fly-by-wire system.

In the event of loss of hydraulic power, the ailerons cannot be operated, the on-board computer/avionics will also fail, if there is no power. The EPU (Emergency Power Unit) will re-establish hydraulic and electrical power, but this doesn't happen instantaneously. It takes some seconds.

During this critical window, what allows the F-16 to remain in stable flight in the context of RSS?

Reading this PDF it seems that the F-16 can be unresponsive to pilot input, yet remain in stable flight.

My question is, how is this achieved? How is it possible?

My own reasoning:

Either the F-16 is not as inherently unstable as I'm given the impression it is, or, there is enough hydraulic power and electrical power left in the interim between power from main hydraulics to switching to the EPU to allow the fly-by-wire system to keep the aircraft stable.

• Make a scale model of an F-16 and throw it. It is designed for supersonic flight, and may only need computer help under certain conditions. A few seconds in straight and level subsonic flight (most of the time) should be enough time. If your F16 is too unstable, see what can be done to make it more stable if you are thinking of using it for passenger service (without computers). – Robert DiGiovanni May 24 at 14:12
• – fooot May 24 at 15:18
• The battery would provide power to critical things like the FBW computers, and a pressurized hydraulic system bleeds down, rather than going to zero instantly. Perhaps this combination is enough to keep the aircraft from departing controlled flight while the EPU starts. – Ralph J May 24 at 15:46
• @Robert DiGiovanni I've heard this before, and I don't understand its relevance. The center of gravity highly influences stability on any aircraft. What exactly is the center of gravity on the F-16? Also, I'm not convinced that a tiny F-16 model exhibits the same aerodynamic properties as a full scale model. Aerodynamic forces change as a function of speed and air density, the model might exhibit stable flight, while the full scale model may not. I would need to see a reference for this -- that a scale model F-16 can be used to exactly simulate a real F-16. – AlphaCentauri May 24 at 15:48
• @fooot I've edited my question to explain how this question is different. – AlphaCentauri May 24 at 15:50

• @RobertDiGiovanni But if you go too slow, the cat will be waiting Which is probably why most of the Hill AFB crashes I recall (from the period my parents lived in that area) were on landing or takeoff. Lose fly-by-wire at 50 feet at 20 kt above stall, and you've got a problem... – Zeiss Ikon May 24 at 18:05