knot4u
Repeat Offender
I'm just a dumb mechanic but wouldn't the potential be the altitude and the kinetic be what got you up there? Unless you meant if something went wrong.
Too high for my comfort level...
- Thread starter SteveC
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🦈💜
Well-Known Member
Thread title reminds me of a time I was flying from LA to San Francisco a few years back. For some reason, I had raised my seat almost all the way up during cruise, probably to avoid the sun. Suddenly, as we started on the arrival, I noticed. I turned to my FO and I said “Boy, I am really high right now!”
After a brief pause, I amended “my seat. My seat is really high. For the CVR.”
After a brief pause, I amended “my seat. My seat is really high. For the CVR.”
Minuteman
I HAVE STRONG OPINIONS ABOUT AUTOMOTIVE LIGHTING!
You're describing a constant-energy dive. This was a technique used by some "third gen" fighters to minimize the time needed to get somewhere high and fast. The dive was used to accelerate through the transonic drag-rise where the thrust and aerodynamics didn't match-up to allow for a climbing acceleration or even a timely acceleration in level flight.
The solution was the maximize the power input to the vehicle to gain altitude and some speed on the most-efficient path/speed schedule (an "energy climb," maximizing the specific excess power, Ps), then descend along a constant-energy contour, using all the thrust available plus converting some of that potential energy (h) back into kinetic input as the drag-rise gulped it down while still accelerating. Eventually the aircraft got to a point where maybe they were on the back side of the transonic drag rise and had descended & accelerated enough that the engines could produce enough thrust to continue climbing and accelerating on a energy climb for supersonic conditions.
BobDDuck
Island Bus Driver
You're describing a constant-energy dive. This was a technique used by some "third gen" fighters to minimize the time needed to get somewhere high and fast. The dive was used to accelerate through the transonic drag-rise where the thrust and aerodynamics didn't match-up to allow for a climbing acceleration or even a timely acceleration in level flight.
The solution was the maximize the power input to the vehicle to gain altitude and some speed on the most-efficient path/speed schedule (an "energy climb," maximizing the specific excess power, Ps), then descend along a constant-energy contour, using all the thrust available plus converting some of that potential energy (h) back into kinetic input as the drag-rise gulped it down while still accelerating. Eventually the aircraft got to a point where maybe they were on the back side of the transonic drag rise and had descended & accelerated enough that the engines could produce enough thrust to continue climbing and accelerating on a energy climb for supersonic conditions.
Obviously the drag rise for a Lear going from M=0.64 to 0.7 isn't going to have to deal with any significant transonic drag rise. There's nothing to "get through" and its only going to get worse until there's no more excess power to continue climbing or accelerating. You'd be better-off staying lower and accelerating faster for the trip (all-else equal) ... but that doesn't mean 'climb at VMO/MMO' either; there's an optimum some where between wheezing and screaming at each altitude, speed, and weight.
And now I'm suffering from flashbacks to my third year in college.
///AMG
Well-Known Member
Yeah I believe that to be the case as well. It's been a while since I was flying down there, but we did detachments a number of times to KSAV and used the W137-140 complex for air to air intercept training. The 137/138/140's were exclusive use for mil traffic but the 139's were co-use. Kind of a strange arrangement. Anyway, most days there would be a lone Gulfstream test jet up in the 139 row just blasting up to the moon. We'd keep an eye on them with the radar just to make sure we were deconflicted (since we'd be working a discrete freq), and you'd regularly see them anywhere from FL450-500+. No thanks, you can have that air Gulfstream
(this was I believe either 650 or 700 testing that we observed from afar)
///AMG
Well-Known Member
We called this the Rutowski Climb.....still used by some aircraft, though of course the specific numbers vary.
Soul Brotha'
Off to go do Black guy stuff
What the heck did you study in college?
I was more of Human studies to squeak on by to get through the 4 years.
KLB
Well-Known Member
Yeah I believe that to be the case as well. It's been a while since I was flying down there, but we did detachments a number of times to KSAV and used the W137-140 complex for air to air intercept training. The 137/138/140's were exclusive use for mil traffic but the 139's were co-use. Kind of a strange arrangement. Anyway, most days there would be a lone Gulfstream test jet up in the 139 row just blasting up to the moon. We'd keep an eye on them with the radar just to make sure we were deconflicted (since we'd be working a discrete freq), and you'd regularly see them anywhere from FL450-500+. No thanks, you can have that air Gulfstream
The Challenger 300 is capped at 450 because it couldn't meet the decompression certification requirement unless tail fins on the bottom of the fuselage (like you see on learjets) were added. Bombardier deemed that look bad for marketing the plane. So they just capped it at 450 and called it a day.
BobDDuck
Island Bus Driver
Aerospace and mechanical engineering.
You're describing a constant-energy dive. This was a technique used by some "third gen" fighters to minimize the time needed to get somewhere high and fast. The dive was used to accelerate through the transonic drag-rise where the thrust and aerodynamics didn't match-up to allow for a climbing acceleration or even a timely acceleration in level flight.
The solution was the maximize the power input to the vehicle to gain altitude and some speed on the most-efficient path/speed schedule (an "energy climb," maximizing the specific excess power, Ps), then descend along a constant-energy contour, using all the thrust available plus converting some of that potential energy (h) back into kinetic input as the drag-rise gulped it down while still accelerating. Eventually the aircraft got to a point where maybe they were on the back side of the transonic drag rise and had descended & accelerated enough that the engines could produce enough thrust to continue climbing and accelerating on a energy climb for supersonic conditions.
Obviously the drag rise for a Lear going from M=0.64 to 0.7 isn't going to have to deal with any significant transonic drag rise. There's nothing to "get through" and its only going to get worse until there's no more excess power to continue climbing or accelerating. You'd be better-off staying lower and accelerating faster for the trip (all-else equal) ... but that doesn't mean 'climb at VMO/MMO' either; there's an optimum some where between wheezing and screaming at each altitude, speed, and weight.
CFI A&P
Exploring the world one toilet at a time.
It isn’t necessarily the decompression that is the issue, but the requirements to meet 25.841 and other related regulations.