Flying to Hawaii

[501261]

Why would I ever trust someone who quotes NBAA stats? NBAA is so full of crap it defies description. By their definition Legacy pilots should make 110K a year. Considering I know 90 percent of the Legacy drivers in the USA I think it is safe to say nbaa is full of crap.

For once I agree with you, but a lot of us think the NBAA numbers are skewered too low. Welcome to the corporate world!

 

[bigD]

Question: if the Legacy has been tested for a higher max diff, or at speeds beyond .92, why would the company intentionally set the limitations so much lower? You mention cost reasons - how does setting the limitations lower help with costs? This is an honest question - I don't know the answer.

It seems to me that this is all a moot point anyway. Max diff in the Legacy is 8.3. Period. Who cares if it can do more? The fact that it might handle more doesn't help your guys in the back who are suffering in a 9000 foot cabin. Perhaps future Legacies will be better, but we're comparing existing airframes, right?

 

[GVFlyer]

Awesome post, GV! But, do you sometimes get the feeling that you're arguing with some kid who just got a Legacy module for his Microsoft Flight Simulator program?

-SkyGirl-

Yes.

GV

 

[AA717driver]

Here's the real deal-breaker: How many bizjet pilots out there have to wear David Clarks cause the COCKPIT IS SO **CENSORED****CENSORED****CENSORED****CENSORED**ED NOISY? (shouting because LD is probably deaf from the wind noise)

BTW, the other night, we took 5:40 and burned 14k in gas to go from EWR to LAX with 120 kt headwinds till we got to ALS. We had to slow down to M.83 so we could climb to FL470 over MCI. This thing is a beast! TC

 

[GVFlyer]

I am arguing with morons it is clear.

First of all, the Legacy cabin has a stated max diff of 8.3 psi. This limit is artificial. The airplane was tested to withstand pressures greater than those required by certification. 8.3 was chosen for reasons of cost not strength.

I expect a check for all the instruction I have been giving you. You have finally blundered into an area that I know far better than I want to after successive certification programs on the GV, the G550 and the G450.

Aircraft are certified to a standard and that standard becomes a limitation. Airframers are very reluctant to redo any portion of the certification process for an aircraft that has earned a type certificate because to do so is very expensive. In the case of pressurization, the standards are much higher for aircraft that fly above 45,000 feet than for those that fly at and below that altitude. This excerpt is from the regulation that establishes certification requirements for transport category aircraft (emphasis added):

Sec. 25.365 - Pressurized compartment loads.

For airplanes with one or more pressurized compartments the following apply:

(a) The airplane structure must be strong enough to withstand the flight loads combined with pressure differential loads from zero up to the maximum relief valve setting.

(b) The external pressure distribution in flight, and stress concentrations and fatigue effects must be accounted for.

(c) If landings may be made with the compartment pressurized, landing loads must be combined with pressure differential loads from zero up to the maximum allowed during landing.

(d) The airplane structure must be designed to be able to withstand the pressure differential loads corresponding to the maximum relief valve setting multiplied by a factor of 1.33 for airplanes to be approved for operation to 45,000 feet or by a factor of 1.67 for airplanes to be approved for operation above 45,000 feet, omitting other loads.

Tell me again how the Legacy will climb to 51,000 feet.

Secondly, the Legacy was tested to beyond .92 Mach, making 0.80 an artificial limit (with a .92 test Mmo could be raised). Raising Mmo is not something Embraer is going to do right now but it could if it chose to.

A little bit of knowledge is a dangerous thing. Yes, in fact the EMB-135 was flown to M 0.92. I know this because the FAA's Atlanta Certification Office certified the aircraft; they are same group who does certification for Gulfstream. As a matter of fact, much of Embraer's certification was done from Gulfstream's ramp. The FAA test pilots would come up to the Customer Lounge right in front of Gulfstream Flight Test to debrief the flights with the Embraer test pilots and flight test engineers. I know how they established limit speed and I'll tell you how it was done, but first we have to look at the regulation again, this time to learn about aeroelastic stability requirements:


Sec. 25.629 - Aeroelastic stability requirements.

(a) General. The aeroelastic stability evaluations required under this section include flutter, divergence, control reversal and any undue loss of stability and control as a result of structural deformation. The aeroelastic evaluation must include whirl modes associated with any propeller or rotating device that contributes significant dynamic forces. Compliance with this section must be shown by analyses, wind tunnel tests, ground vibration tests, flight tests, or other means found necessary by the Administrator.

(b) Aeroelastic stability envelopes. The airplane must be designed to be free from aeroelastic instability for all configurations and design conditions within the aeroelastic stability envelopes as follows:

(1) For normal conditions without failures, malfunctions, or adverse conditions, all combinations of altitudes and speeds encompassed by the VD/MD versus altitude envelope enlarged at all points by an increase of 15 percent in equivalent airspeed at both constant Mach number and constant altitude. In addition, a proper margin of stability must exist at all speeds up to VD/MD and, there must be no large and rapid reduction in stability as VD/MD is approached. The enlarged envelope may be limited to Mach 1.0 when MD is less than 1.0 at all design altitudes...

What's key here is that 15% speed margin increase required by paragragh B.(1). The FAA test pilots encountered elevator flutter in the unboosted elevator flight controls at M 0.92. Flutter is dangerous because it is a destructive mode. Test pilots at the Big G get a bonus for doing flutter testing, even though no one has actually encountered flutter during a Gulfstream Developmental Test and Certification program. But, here's how the M0.80 was established. You must have a 15% margin between constant Mach number and flutter. Watch this: M 0.80 X 1.15 (a 15% increase)=M 0.92 - the speed at which the FAA guys (and a gal named Carla) scared themselves!

The plane outperforms in every category what the books says by a significant margin.

Extremely unlikely. The only certified data in your Aircraft Flight Manual is takeoff and landing data. Cruise manual data need only be, "representative of a test article in the test program." What this normally means is that cruise manual numbers are derived from flights in uncompleted,"green" aircraft during the Function and Reliability testing part of certification and are thus wildly optimistic. Gulfstream and Boeing are the only manufacturers that print conservative figures in their cruise manuals. For instance, Gulfstream knew that the GV would fly 6500 nm, because they had repeatedly flown ballasted GV's in excess of 6700 nm during F&R testing. The record for these flights belongs to Ron N, a former 89th Squadron guy, at 14 hours 47 minutes and 6774 nm at M 0.80. The G550 was flown over 6900 wind adjusted nautical miles during F&R testing.

Why would I ever trust someone who quotes NBAA stats?

Well, I didn't think you would believe me if I sent you to the Gulfstream Customer Website, either.

NBAA is so full of crap it defies description. By their definition Legacy pilots should make 110K a year. Considering I know 90 percent of the Legacy drivers in the USA I think it is safe to say nbaa is full of crap.

I agree, I think NBAA pilot compensation numbers are too low to be accurate.

Keep living in your fantasy world. I will enjoy seeing your broke d*ck peachjet in the MX hangar as I taxi by.

Statistically, it is much more likely to occur the other way round.

Parlaying with fools is a lost cause.

Yes, I know, but I feel a social responsibility to help educate the junior birdmen in our aviation community, so I stick with you.

GV










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[fokkerjet]

GVFlier

I knew there was a benefit in trashing Gulfstream's........free education

He!!, if LD won't cough up any cash, I will....just reading your responses is worth something!

 

[capt_zman]

I don't think I've seen a spanking like this is quite some time. Not bad for a moron

 

[mmmdonut]

Hey.... if you accidentally let go of the Gulfstream tiller, does the nosewheel snap back to 0 degrees?


Just wondering....

 

[suen1843]

Hey.... if you accidentally let go of the Gulfstream tiller, does the nosewheel snap back to 0 degrees?


Just wondering....

Gulfstream pilots NEVER do anything accidentally !!!

 

[LegacyDriver]

A company can certify a jet below what it would qualify for folks. If your mmo is .83 you fly at .83 and burn gas. I am sure EMB initially restricted speed to .78 on the RJ for efficiency and this is a carryover. My understanding is the airplane was tested in Brazil beyond (BEYOND as I stated previously) .92 M and the did not get flutter. They got Mach buffeting but not flutter (and I am under the impression they are not the same thing though you will surely correct me).

8.3 diff is the stated max psid. Again, this is a conservative limit placed on the plane by EMB just as the original limit on the ERJ was (on the ERJ 8.3 was called OVERPRESSURE not max diff--max diff on the RJ w/the same tube was 7.8 or 8.1...been awhile).

As for all the rest:

DC headsets - don't see anyone wearing those in the Legacy. This airplane is significantly quieter than the ERJ. New windows, no wipers, sound insulation...

Hyd pump whine - taxi on engine 1 and leave pump 2 off. Big deal (no whine in the Legacy like the RJ any way). Have you people ever even seen a Legacy II????????

Embraer is also very conservative with its numbers. The plane outperforms the book in every category and operators are discovering that every time they fly it.

I know there is more but my head hurts.

It is a fine airplane. Those who trash it are ignorant or have the ulterior motive of perpetuating bad info to keep this plane from being a success. Else why would you continue to quote outdated articles?