"borrowed" this from a thread over at RL. I understand why there are restrictions on breaking the sound barrier, but if this plane can safely fly at Mach .99, why is it limited (per its "maximum speed") to Mach .86? [ame]http://www.youtube.com/watch?v=c7ojhYSSMKc[/ame]
I have a lot of time in Falcon 50s. I believe the reason they didn't certify it to a higher speed was that it wouldn't fly at those high mach numbers in level flight, and thus no reason to bother to certify it to those speeds. In my experience, it was difficult to get above 0.82 - 0.83 unless you were either going downhill or maybe fairly low and burning a lot of fuel. In contrast, we used to fly the Falcon 10 at mach 0.85 fairly regularly. Of course, the Falcon 20 undermines this argument, since it's certified to mach 0.86 (I believe) and it has no hope of even getting to mach 0.80 in level flight with the original engines.
This is getting into a realm where the air doesn't know what the heck to do so it does unpredictable things and flying in this range could be full of surprises. High fuel gulping too due to very high drag that rises exponentially.
Also, another reason is that in order to certify an aircraft to a certain Mmo, you need to demonstrate flight at 0.07 mach above the proposed Mmo. This is why the Citation X is certified to a mach 0.92 Mmo-- they had to demonstrate flight at mach 0.99. If they wanted to go higher than 0.92, they would have had to demonstrate flight above mach 1.0, and that results in various issues.
Was the top speed reached .97 or .99? Years ago I was in the back of a falcon 20 over south america when the pilots had to make a full power decent because it iced up. It was a wild ride.
I recall many years ago when I was an engineer at Cessna and involved in flight test work, one of the flight test conference rooms had a plaque that commemorates a flight where the X when supersonic. I think that Chuck Thornton's T-38 (N638TC) was flying chase for that event since it was the only chase aircraft available that could keep up.
Yeah, it's been discussed here before and is pretty well documented. From what I gather there have been several instances where various airliners have been taken supersonic.