CptColumbo
Just One More Question
A Kiwi conspiracy is the last thing I would suspect.
Jeff Hill's latest claim
- Thread starter leftysergeant
- Start date
-
- Tags
- jeff hill no planers
No, not really. There is an ICAO speed limit of 250 KIAS below 10,000 MSL. There is an additional speed limit of 200 KIAS within 10 NM of an Airport. The approach speed of most airliners would be in the range of about 135-150 KIAS depending upon weight and specific type.
Military fighters/trainers are exempt from these speed restrictions as their Flight Manuals calls for higher speeds in these areas.
Last edited:
Gravy
Downsitting Citizen
- Joined
- Mar 27, 2006
- Messages
- 17,078
Fun!
OldTigerCub
Striped Shapeshifting Reptoid
- Joined
- Sep 16, 2007
- Messages
- 1,619
That looked incredibly dangerous. I half expected it to cartwheel when it went into that turn so close to the ground.
Last edited:
leftysergeant
Penultimate Amazing
- Joined
- Jul 13, 2007
- Messages
- 18,863
In the viseo that Jedd originally posted, he had some software engineer from Boeing commenting to the effect that the turbulace would have caused structural failure.
I think this is a Bollynism. Jeff called someone who was not an authority of the topic and, because he worked at the right company, promoted him too a web hero. Kind of like when Bollyn manufactured his irrefutable piece about the engine at the Pentagon being the wrong one because nobody a Allyson made them.
OldTigerCub
Striped Shapeshifting Reptoid
- Joined
- Sep 16, 2007
- Messages
- 1,619
As that video started I was a little afraid it might be similar to this one:
Sword_Of_Truth
Penultimate Amazing
- Joined
- May 8, 2006
- Messages
- 11,494
Cheap Shot
Critical Thinker
- Joined
- Jul 10, 2007
- Messages
- 387
250 a piece of cake, more like he was quoting the FAR's 250 Knot Rule below 10 K. I had a Swiss Air B747 Special which are shorter but faster than regular 747's, I was trying to get spacing on him from a B767 that he was even with. The Swiss Air was already grounding about 40 knots fater, but I had about 200 NM to work with and they were converging, I figured I would ask him if he could go faster. Above 28,000 ft we use Mach numbers for adjusting speed, I asked if he could pick it up and he told me he was already doing .91 Mach, (most B747 fly at Mach .84) I was kind of shocked that he would be going that fast, so I asked him how fast it would go, he told me when they get up around .95 or .96 Mach the aircraft begins to buffet (from the sound barrier) I almost couldn't beleive it. So question for REHEAT, in a slight dive could the B747 Special break the sound barrier? Any other pilots? Just wanting to know.
No, I don't believe so. It would severely buffet and might "tuck" severely prior to going through the Mach for the whole aircraft. That's an educated guess BTW.
I do know of one incident in which the crew insists they went supersonic, but there's no proof that I know of. It was a night flight over Canada where the INS drifted severely and the aircraft was in an unusual attitude when the Captain noticed it was wacko. He recovered on the standby ADI, fortunately guessing correctly which one was wrong. They lost about 15,000' during the recovery. The maneuvering overstressed the aircraft and I don't know if it ever returned to service.
IIRC, they experience a severe compressor stall and flamed out 1 engine during the recovery, as well.
It is possible that if one could actually get past .96-.98 that "mach crit" would be reached on parts of the aircraft. Basically, that means that parts of the aircraft would be supersonic and there would be a boom on the ground, just not quite as loud as it would be if the whole aircraft was going Mach 1.
I would not volunteer to be the test pilot for determining if it were possible.
Last edited:
You're talking about China Air 006. I mentioned that and another example the last time this came up, as it does periodically.
Getting a big transport over Mach 1 is doable, particularly if you don't care whether or not you live to tell about it. Getting one up to ~600 MPH at low altitude isn't so difficult. Exceeding 250 knots below 1000 feet AGL is utter child's play, provided you're not in an Airbus or you know how to deactivate the matronly autopilot. No difficulty in a Boeing whatsoever.
Engines and Airframe wise on a Boeing, I do agree with you. The key words here are "care whether or not you live to tell about it". Anyone that I know wouldn't intentionally try as it's pretty risky. Also, generally folks who fly big airplanes don't own them and most owners take exception to someone potentially crashing their airplanes just for the thrill!
leftysergeant
Penultimate Amazing
- Joined
- Jul 13, 2007
- Messages
- 18,863
Excuse me? Does that low-altutde, high-speed pass pf the Airbus down the runway sort of stamp BS all over the assertions that "ground effect' would have kept Flt 77 from hitting the Pentagon? Or was that one of the reasons that all the aircraft were in a slight left bank when they hit?
(I know, I was in the Air Force and should have learned more about this sort of thing, but I didn't fly the planes. I was just there to hose down the pieces when somebody flew one wrong.)
(I know, I was in the Air Force and should have learned more about this sort of thing, but I didn't fly the planes. I was just there to hose down the pieces when somebody flew one wrong.)
Hello leftysergeant, did you just arrive to this thread?
There are at least 4-5 posts and 3-4 videos addressing the issue in this thread alone. Ground effect occurs below an aircraft approximately within it's wingspan. It is most pronounced at high angles of attack such as during the approach and landing phase. It does create a minor "cushion of air" during landing that is easily countered by pilot input.
Any aircraft (without an autopilot override) can fly close enough to the ground to tie the world record for low level flight at whatever speed it is capable of flying, even supersonic. Depending upon the aircraft's wing loading and thermal conditions, turbulence can be worse than the minor effects of "ground effect". So yes, those videos put the issue to rest along with hundreds of other videos yet to be seen.
Gravy
Downsitting Citizen
- Joined
- Mar 27, 2006
- Messages
- 17,078
Lefty, there's a detailed discussion of ground effect and conspiracy claims at aerospaceweb. Anyway, flight 77 was at an altitude where ground effect may have come into play for about one second. Conspiracists would have us believe that it was buzzing along at grasstop level across Virginia.
Last edited:
Elizabeth I
Philosopher
In any case, even in those planes, as long as you stayed in relatively level flight, couldn't you go at just about any speed regardless of your altitude?
Apparently not.
http://www.aerospace-technology.com/projects/a320/
It is obviously a different system than that invented by General Dynamics present on the F-16. That system only limits AoA and indirectly G. It does not limit speed. The system on the Airbus design obviously is more sophisticated in that it does involve more parameters to include AoA, Bank Angle, G, stall speed and operating limit speed.
Reheat, I know there is a simple answer for this so please humor me.
How can one part of an aircraft go supersonic without the "whole aircraft" doing so?
Interesting thread guys...
Different shape and/or angle of attack. Perhaps R. Mackey can explain it better than I can.
Bear in mind that the Mach Indicator is sensing at the pitot tube not on the wings and other places on the aircraft.
Basically, there may be points on the wings or other parts that achieve Mach Crit prior to a Mach 1 indication in the cockpit.
There's an interesting story about this phenomena that occurred at an airport off the West Coast of Scotland. It was a young LT crew in an F-111F making a high speed pass down the runway below Mach 1. They did a pull-up and midfield and reached Mach Crit even tho' it was not indicated in the cockpit. It just happened that President Reagan was visiting shortly afterward and Margaret Thatcher presented him with a bill for the damages to residences in the surrounding area. Needless to say those two LT's were out of the County within 24 hours. I don't believe either of them ever flew again.....
Last edited: