Flight Test Support Success Stories
F-16 Modular Common Inlet Duct Flight Test Support

F-16 MCIDAs the F-16 propulsion systems have evolved, the requirement to increase the inlet throat and capture area for increased engine mass flow led to the development of the Modular Common Inlet Duct (MCID) for the Block 30D aircraft. Initial flight testing with this inlet configuration revealed deep stall behavior that was more oscillatory and more difficult to recover from. Bihrle Applied Research had collected a substantial set of static and dynamic wind tunnel test data for General Dynamics and the US Air Force, with evidence of degradation in the dynamic characteristics for this configuration. Following a flight test deep stall encounter with a center line tank configuration that required over 30 pitch rock cycles before recovery, Bihrle was tasked to review the flight results and support configuration modifications to alleviate the deep stall conditions.

During the review of the data, the MCID configuration effects were added to the Bihrle in-house F-16 engineering simulation, and our engineers were able to replicate the extended recovery deep stall observed in flight. Review of the flight data revealed a number of issues that delayed recovery. The oscillatory nature of the deep stall with this configuration aggravated the ability of the pi synchronize his pitch rocking inputs, as the roll oscillation phasing gave the illusion of a nose down pitch break. Since the yaw rate limiting function of the flight control system at high angles of attack had priority over the longitudinal control, the yaw on the airplane during this oscillatory condition was severely limiting the available nose down control. Following these insights, the yaw rate limiting component of the flight control system was modified in the engineering simulation to respond less immediately to the yaw rate buildup, thus enabling greater pitch control. With this modification in place, previously difficult recoveries were now immediate. This change to the yaw rate limiting circuit was recommended to the Air Force, approved, and successfully flight tested. The success of this modification on the deep stall recoveries was sufficient to lead to the retrofitting of all F-16 configurations.

Did you notice the slightly swept environmental intakes on the big-mouths and the non-swept ones on the small mouths? Well, the splitter between the top of the intake and the bottom of the fuselage is swept on big-mouths and not swept on small-mouths.

I never knew that ... I would have to say that is the tip of the month ... good observation

But, like I said, I have never heard the sound of an F-16 with a P/W engine in it.

Yes you did, you may have not realized it though

Ever see the T-Birds?