Now, what limits do I run into? Mach buffet? I doubt it, at sea level. Structural failure? Flutter, as has been suggested here? Or do I simply run out of "puff" anyway? Let me add I do not intend to pull significant 'g' in the process, just do a real high-speed run to the real limit.
Transport category aircraft certificated under Part 25 do not require a Vne speed, as Part 25 doesn't require establishing Vne. Part 25 requires that up there be no adverse characteristics up to Vmo/Mmo, and above that speed up to the maximum design speeds, no adverse characteristics that are not easily handled by the crew in recovering back to Vmo/Mmo. What will happen if you accelerate through Vmo at low level? Nothing. The specific characteristics that will be encounterd depend, as has been repeatedly stated thus far, on the specific aircraft and configuration.
You want to know what's going to happen if you push the power up and fly to the maximum design speed? Nothing.
Will you get buffeting? Possibly. Depends on the design. Depends on the configuration. Depends on the loading and other factors. Will you run out of trim? No, not up to the design speed, but again, this will really depend on the airplane, how it's configured, loaded, etc.
Does the airplane have the power to reach that speed in level flight? Depends on the airplane and it's loading. It might. Some aircraft do, some don't.
Is exceeding Vmo part of a windshear recovery, as previously suggested? Of course not. It's a ridiculous idea.
Do manufacturers and repair facilities routinely push the airplane to it's design limit speeds to see if the old gal can still do it? No.
While I have no experience in that aircraft, my informal survey of Lear pilots on this subject state that high speed characteristics vary from nothing to buzzing, to full on tucks, that have killed some guys...who knows...all this happening in the .82+ region...not very fast...
Sim warriors. Those characteristics just don't exist in the Lear, especially at .82 Mach. Pete Reynolds, a test pilot for Lear, wrote a good paper on the subject, in which he described taking the airplanes to speeds well beyond those numbers with no adverse characterstics. I've heard the stories too, mostly from pilots who saw it happen in the sim and assumed it happens in the airplane...it doesn't. I've had the airplanes to speeds well above .82, and there are no bad habits lurking there. Even with the earlier wings.
I recently spent time in a LR35A that not only was modified with pylons on the wings and hardpoints, but flying it configured with external stores and gear throughout it's flight envelope, including frequent flights in turns to the shaker with all ranges of AoA explored...and still no bad habits...despite plenty of ways to disrupt airflow over the wing.
The stories of ailerons causing the flight controls to slam from side to side, the terrible dutch roll charactersitics at high altitude following a yaw damper failure, and so on...all untrue. The mach tuck characteristics are so mild that the solution for it is mach trim...slight nose up trim. The only reason it's a concern at all is that the controls become light enough that they don't quite meet the Part 25 requirements for stick pressure...but it's fully manageable, fully controllable...all myth floating around out there. How many of those pilots that you questioned have actually experienced those effects in the airplane...and how many had this first hand knowledge from their sim experience? You're not going to find pilots who experienced those problems in the airplane, because they're sim-isms.
I'm given to understand Vne as marked on the ASI is predicated on standard temp & pressure, and should be factored for altitude - i.e. the IAS will underread at alt due to density, but VNE is a constant *airstream* speed. Or to put it really simply, cruising along at 20,000ft you could hit flutter while the ASI was well short of the redline.
No, not really. Flutter isn't a function of actual speed, it's a function of air density, because it's a function of the atmosphere acting on the control surface or flying surface. The surface has no idea how fast it's actually going. That at a higher density altitude the TAS may be higher has no bearing on fluter issues.
IAS is an imperfect medium through which to consider flight characteristics. Corrected for position error, CAS is often used as a reference in charting and data, but is also inadequate to consider the aerodynamic effects on the airplane, and should be discussed in terms of Equivilent Air Speed, or EAS. To simply our use in the cockpit, and discounting minor error excursions, we stick with Indicated Air Speed (IAS).
If the mass airflow around the wing and it's relevant pressure distributions indeed account for flutter, we can measure it in flight with indicated airspeed. If indicated airspeed drops, we move farther from flutter, or in other words, create a bigger margin. It's air density that determines the speed necessary to produce the same impact force in the pitot tube, and it's the same density that determins flutter. Airspeed decreases, flutter margins increase.
Again, this is simplification, but simply because density altitude has increased does not imply that flutter is achieved at speeds less than Vne. Moreover, whereas Vne is established with a margin already built in, it's just not going to happen unless control balance has been changed or other changes are made to the wing or control system which decrease susceptability to flutter to a lower speed.
Some elements of flutter do occur at lesser speeds, but are addressed by airframe limitations. In the B747 Classic, for example, a limitation exists regarding reserve fuel between FL290 and FL340, with reserve fuel on board, related to speed characteristics. This speed limitation does not exist at other altitudes or when the aircraft weight is outside the parameters of the limitation, or if the additional reserve tanks are not filled. The issue is addressed by the manufacturer.
One would need to differentiate between control flutters or airframe flutters...and we could diverge off on all kinds of tangents. I don't believe the original questions intended that, however, nor are they particularly relevant to the central question of what we experience when accelerating in level flight to a particular design speed. In the range of operating speeds we're going to see, within prescribed limitations for the aircraft we fly, we're not going to encounter adverse characteristics.
The question was asked about accelerating to Vmo on engine thrust...are we going to run into some kind of wall or limiting flight characteristics? No. We're either going to run out of excess thrust as the drag rise rapidly exceeds available thrust and thus stop accelerating, or we're going to hit airspeed limitations and need to reduce the thrust in order to maintain them. This may be complicated by maneuvering and loading the airplane/increasing angle of attack, but then we're back to buffet margins...and even at the upper speed limits at low altitude we're exploring the lower buffet margins when we either operate at critical AoA's...we've simply raised the buffet margin to a higher number. We're not touching upper buffet margins...the mach limits of the airplane aren't usually attainable because they're far above the IAS limitations at lower levels.