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Offline wilsonphil

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Gulfstream has come a LONG way
« on: October 22, 2019, 08:27:50 PM »
https://www.flyingmag.com/gulfstream-unveils-g700/

its really impressive they can maintain a 4800ft cabin @ 51,000 alt while cruising around at M .925 and for a mere 75 million one can be yours after 2023

Offline dave945

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Re: Gulfstream has come a LONG way
« Reply #1 on: October 22, 2019, 09:11:44 PM »
That’s nice, enough space to seat the whole family, and with delivery in 2023, that gives me four years to earn the 75 mill for it. What could go wrong?


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Offline JR

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Re: Gulfstream has come a LONG way
« Reply #2 on: October 23, 2019, 12:34:02 AM »
Lotto is worth around 110mil tomorrow.

You could order one, have the $$ to maintain and have Don fly it.
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Offline Superwhdm

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Re: Gulfstream has come a LONG way
« Reply #3 on: October 23, 2019, 07:51:04 AM »
Im curious how they incorporate surround sound with NO speakers.  Using the interior panels as resonance material is interesting.  Id also like to see the capability of the led lighting system. 
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Offline cruizng

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Re: Gulfstream has come a LONG way
« Reply #4 on: October 23, 2019, 07:59:54 AM »
Phil, Is there an FAA rule that business jets can't break the speed of sound?

"maximum cruise speed of Mach 0.925." Close but not breaking.  :popcorn:
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Offline wilsonphil

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Re: Gulfstream has come a LONG way
« Reply #5 on: October 23, 2019, 10:58:02 AM »
No there is not, WHERE they can break the sound barrier is controlled.  IE the Concord had to accelerate and decelerate out over the ocean so that all the little libs wouldn't complain about the noise(sonic boom), the big RULE that would be adventitious above 50K altitude there are no airways you have to fly, you can "go direct"

Then there is a whole bunch of OTHER rules that need to be taken into consideration.  One big requirement is maintaining the cabin on one engine, if you were to loose an engine at altitude and could not maintain cabin pressure you would have to drop altitude so you and the passengers could breath but when you drop altitude you burn lots more fuel.  and you need to make your alternate airport.  When the twin engine long haul jets came on the scene they were required to fly completely different routes than say a 747.  it was all to do with single engine performance.  Now that they have proven the new engines are pretty reliable the routes have been allowed to be modified. 

But then there is physics, that number .9 Mach is what it s capable but they would almost never cruise there, fuel burn would be high.  but lets say a Business Jet could go supersonic and maintain that speed, it requires power and power requires fuel and lots of fuel if you want to go anywhere.  Also the compressability comes into play once you start going higher so you burn less fuel because the air is thinner you have to go faster to still create lift on the wings so you see its a compounding problem. (rockets dont have this problem)     THEN there is the issue what happens if you lose an engine while supersonic, with today modern flight computers it might be able to catch and compensate for the power loss.  the engines on most jets are far apart so it is a big issue when you are supersonic.

A good example is the B58 Hustler one of my favorite planes, its was capable of Mach 2.5ish and one day the Air Force lost one at altitude and while supersonic.  SO the theory was the plane lost and engine and the crew could not recover/react in time to save it.  SOOOOOO the Air Force in their infinite wisdom said lets see what will happen if we go supersonic and deliberately pull/reduce power on one of the engines, the result was you lose the plane and crew it came back in very small parts.  Not too long after that the B58 was retired from service.  A lot of that had to do with the engine spacing, look how far apart the engines are on that plane.   

This is very undetailed flight dynamics Ii am speaking here!  This is much more in depth conservation, but when I say how far Gulfstrem has come, when I was active in that business the G2 had what was know as a wet footprint, if I was say flying to Hawaii and I lost an engine in a certain 200NM window I did not have enough fuel to turn around and go back and I could not make the island so I'm in the water (wet footprint), this was because I could not maintain altitude/cabin pressure on one engine so I had to drop down and dropping down burns lots more fuel.

The G2/3 series jet used a RR Spay engine that were total gas hogs, G2/3 didn't have fuel dump, all we had to do was drop down to 10-12K altitude and just push the throttles all the way up and just watch the fuel totalizer look like a slot machine.



Offline Flyin6

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Re: Gulfstream has come a LONG way
« Reply #6 on: October 23, 2019, 12:19:07 PM »
Mach .92!!!!!!!!!!!!

Holy crap!

I would buzz around at .83 and feel like I was something.

That is movin!
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Offline Flyin6

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Re: Gulfstream has come a LONG way
« Reply #7 on: October 23, 2019, 12:30:30 PM »
Phil, Is there an FAA rule that business jets can't break the speed of sound?

"maximum cruise speed of Mach 0.925." Close but not breaking.  :popcorn:

It's like almost too close. One does not flitr with supersonic airflow and the effects of compressibility. The 727 was the only commercial jet I knew of that ran along at .9 mach and that was a bit of a paux-de-deux (Refers to feet as in a dance for two), meaning you were flirting with disaster.

Air foils designed for supersonic flight are very different from subsonic cross sections, and man do I know. Believe it or not, helicopters flirt with supersonic flight and it does some very weird things to our rotor blades. So first of all, the blades are spinning very fast and are already way up on the mach scale. Then we push the aircraft forward which adds to that number. SOme helos are now cruising at 160+ knots so if you had a 500 knot tip speed, you now have a 660 knot speed and are in some conditions, supersonic.

So the air refuses to flow over the blades and breaks apart at the boundary layer, a molecule thick layer that glues air to the blade surface. When that happens, the resulting turbulence creates massive profile and parasitic drag which pulls down the surface. Now move inboard a little bit and the airfoil is producing massive lift and yanking the blade upward. Where the two regions meet, an impossibly high bending force forces the blade tip down and can break it off resulting in a catastrophic breaking up of the now out of balance rotor system.
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Offline JR

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Re: Gulfstream has come a LONG way
« Reply #8 on: October 23, 2019, 01:31:47 PM »
But aren't the airfoils and engines 50 years ahead of those disasters?

With that and new high bypass turbo fans (f35 and 22 supercruise without AB) I think it would be possible.

Correct me if wrong, but at higher altitude you do not hear the sonic boom, more like distant thunder? SR71 ran all the time over without alerting anyone, but it was really high, over 80k.

Think SS is very possible now with both economy and safety, just my opinion.
« Last Edit: October 23, 2019, 03:44:49 PM by JR »
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Offline wilsonphil

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Re: Gulfstream has come a LONG way
« Reply #9 on: October 23, 2019, 02:29:38 PM »
Mach .92!!!!!!!!!!!!

Holy crap!

I would buzz around at .83 and feel like I was something.

That is movin!

And the maker of the C150 was doing it back in the 90's  https://en.wikipedia.org/wiki/Cessna_Citation_X  M .935


Offline wilsonphil

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Re: Gulfstream has come a LONG way
« Reply #10 on: October 23, 2019, 02:35:41 PM »
Phil, Is there an FAA rule that business jets can't break the speed of sound?

"maximum cruise speed of Mach 0.925." Close but not breaking.  :popcorn:

It's like almost too close. One does not flitr with supersonic airflow and the effects of compressibility. The 727 was the only commercial jet I knew of that ran along at .9 mach and that was a bit of a paux-de-deux (Refers to feet as in a dance for two), meaning you were flirting with disaster.

Air foils designed for supersonic flight are very different from subsonic cross sections, and man do I know. Believe it or not, helicopters flirt with supersonic flight and it does some very weird things to our rotor blades. So first of all, the blades are spinning very fast and are already way up on the mach scale. Then we push the aircraft forward which adds to that number. SOme helos are now cruising at 160+ knots so if you had a 500 knot tip speed, you now have a 660 knot speed and are in some conditions, supersonic.

So the air refuses to flow over the blades and breaks apart at the boundary layer, a molecule thick layer that glues air to the blade surface. When that happens, the resulting turbulence creates massive profile and parasitic drag which pulls down the surface. Now move inboard a little bit and the airfoil is producing massive lift and yanking the blade upward. Where the two regions meet, an impossibly high bending force forces the blade tip down and can break it off resulting in a catastrophic breaking up of the now out of balance rotor system.

One of the absolute best examples of this is with this experiment the THUNDERSCREECH    https://en.wikipedia.org/wiki/Republic_XF-84H_Thunderscreech

The tips of this prop were supresonic so you can imagine what it was like to be around on the ground, which was on of the reasons it never went anywhere, noise so the ground crew couldnt work around it, the airframe was getting beat apart, drank fuel and was slow for the day.


Offline wilsonphil

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Re: Gulfstream has come a LONG way
« Reply #11 on: October 23, 2019, 02:38:49 PM »
But aren't the airfoils and engines 50 years ahead of those disasters?

With that and new high bypass turbo fans (f35 and 22 supercruise without AB) I think it would be possible.

Correct me if wrong, but at higher altitude you do not here the sonic boom, more like distant thunder? SR71 ran all the time over without alerting anyone, but it was really high, over 80k.

Think SS is very possible now with both economy and safety, just my opinion.

It really comes to the decompression factor unless you are willing to fly in a pressure suit.  Can you imagine suiting up 100 people in pressure suits, heck people cant even get on the plane with out clogging up the aisle. 

Offline JR

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Re: Gulfstream has come a LONG way
« Reply #12 on: October 23, 2019, 03:51:16 PM »
Concord didn't use em and that was 50 years ago. It was a 4 engine though, old engines.

Think it comes down to if there is a market for a SS private jet, it would be built
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Offline cruizng

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Re: Gulfstream has come a LONG way
« Reply #13 on: October 23, 2019, 09:53:38 PM »
No there is not, WHERE they can break the sound barrier is controlled.  IE the Concord had to accelerate and decelerate out over the ocean so that all the little libs wouldn't complain about the noise(sonic boom), the big RULE that would be adventitious above 50K altitude there are no airways you have to fly, you can "go direct"

Then there is a whole bunch of OTHER rules that need to be taken into consideration.  One big requirement is maintaining the cabin on one engine, if you were to loose an engine at altitude and could not maintain cabin pressure you would have to drop altitude so you and the passengers could breath but when you drop altitude you burn lots more fuel.  and you need to make your alternate airport.  When the twin engine long haul jets came on the scene they were required to fly completely different routes than say a 747.  it was all to do with single engine performance.  Now that they have proven the new engines are pretty reliable the routes have been allowed to be modified. 

But then there is physics, that number .9 Mach is what it s capable but they would almost never cruise there, fuel burn would be high.  but lets say a Business Jet could go supersonic and maintain that speed, it requires power and power requires fuel and lots of fuel if you want to go anywhere.  Also the compressability comes into play once you start going higher so you burn less fuel because the air is thinner you have to go faster to still create lift on the wings so you see its a compounding problem. (rockets dont have this problem)     THEN there is the issue what happens if you lose an engine while supersonic, with today modern flight computers it might be able to catch and compensate for the power loss.  the engines on most jets are far apart so it is a big issue when you are supersonic.

A good example is the B58 Hustler one of my favorite planes, its was capable of Mach 2.5ish and one day the Air Force lost one at altitude and while supersonic.  SO the theory was the plane lost and engine and the crew could not recover/react in time to save it.  SOOOOOO the Air Force in their infinite wisdom said lets see what will happen if we go supersonic and deliberately pull/reduce power on one of the engines, the result was you lose the plane and crew it came back in very small parts.  Not too long after that the B58 was retired from service.  A lot of that had to do with the engine spacing, look how far apart the engines are on that plane.   

This is very undetailed flight dynamics Ii am speaking here!  This is much more in depth conservation, but when I say how far Gulfstrem has come, when I was active in that business the G2 had what was know as a wet footprint, if I was say flying to Hawaii and I lost an engine in a certain 200NM window I did not have enough fuel to turn around and go back and I could not make the island so I'm in the water (wet footprint), this was because I could not maintain altitude/cabin pressure on one engine so I had to drop down and dropping down burns lots more fuel.

The G2/3 series jet used a RR Spay engine that were total gas hogs, G2/3 didn't have fuel dump, all we had to do was drop down to 10-12K altitude and just push the throttles all the way up and just watch the fuel totalizer look like a slot machine.
Thanks for info Phil. It is always fascinating to me.

Well if it won’t go over Mach 1 I guess we will just stay with our Lear45 and CJ. Lol.

I should have picked aviation instead of trucking.


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Offline Flyin6

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Re: Gulfstream has come a LONG way
« Reply #14 on: October 23, 2019, 09:55:31 PM »
Sort of the same thing, only one is higher

(Get it: "Higher")

;-))
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Offline cruizng

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Re: Gulfstream has come a LONG way
« Reply #15 on: October 23, 2019, 09:58:54 PM »
Well if truth be told I didn’t really pick it. It picked me. Needed a job and it went from there.


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Offline TexasRedNeck

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Re: Gulfstream has come a LONG way
« Reply #16 on: October 23, 2019, 09:59:40 PM »
Concord didn't use em and that was 50 years ago. It was a 4 engine though, old engines.

Think it comes down to if there is a market for a SS private jet, it would be built
And then there was that whole fire and crash thing


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Offline JR

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Re: Gulfstream has come a LONG way
« Reply #17 on: October 23, 2019, 11:01:13 PM »
Concord didn't use em and that was 50 years ago. It was a 4 engine though, old engines.

Think it comes down to if there is a market for a SS private jet, it would be built
And then there was that whole fire and crash thing


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Well, running over debris and punchering a fuel tank will ruin your day on most aircraft.
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