Legacy Bashfest - Bring it on!

[ERJ-140]

No no no, I do not intend to get dragged into defending the Legacy. Heavens knows I do not wish to be pilloried as the advocates of the airplane in this thread have.

I will, however, respond with a few thoughts with the hope of rationality behind them.

1)

Much of the certification for the ERJ-135, upon which the Legacy is based, was conducted from our ramp. The same FAA Test Pilots from the Atlanta ACO that worked on GV cert performed the same function for the ERJ-135, as such I have fairly extensive knowledge of the Embraer and it's shortcomings. It is a fragile collection of expedients.

From what I am gathering here you have never flown the Legacy. You have not even flown the ERJ-135. You managed to watch people who did fly it and perhaps talk to them. I am not sure that is a rational basis on which to judge an airplane that has had roughly a decade of development since those early certification days (in the case of the Legacy I believe it has had five years to mature and grow, so the airplane you saw on the ramp is not necessarily the airplane being sold right now).

2) The airplane, being an airliner, was certified to fly anywhere from 2400 to 3600 hours per year. I am not sure that any airplane capable of doing so with the dispatch numbers the ERJ fleet posts could possibly be labled fragile.

3) BC&A data may be inaccurate, I am not one to know, but it is certainly closer to what both LegacyDude and Embraer claim the performance of the airplane to be than C&DD.

In discussions with a friend at Flight Options amon others I am told there are four configurations for the Legacy and that only the first early prototype numbers were posted to C&DD. Embraer has, apparently, and to their detriment, not bothered to correct the data that C&DD shows. I also noticed a Legacy for sale being advertised using C&DD data and it was a serial number down near the 500 range. Embraer already has nearly 850 ERJs and Legacys flying around the world, so it seems clear that C&DD is using old numbers that could have changed since 2000 (the year of the ERJ I saw for sale online).

Again, I am not trying to become and advocate for the airplane by any means, but it seems quite clear that it is not the flimsy toy you claim it to be. It's not a Gulfstream, but it isn't meant to be. I don't particularly see anything wrong with that.

As for contacting C&DD goes, I doubt it would be interested in taking unsolicited data from someone about an airplane it cares nothing about - assuming I was willing to spend the time to do it.

Also, how is a G350, with twice the thrust, twice the weight going to operate for the same cost as the Legacy? Just doing numbers in my head shows that the Legacy burns 325 gallons per hour vs. 450 gph for the Gulfstream 350. Also a window on a G I am told costs about 50,000 to replace compared to about 5,000 for the EMB. Assuming this is even remotely accurate, how can the G350 even come close to the same operating costs? It seems to defy physics for an airplane twice as heavy to run at the same rate as the comparative jet.

Just my thinking on it. Thanks for not flaming. I am prepared to duck shortly.

 

[GVFlyer]

...From what I am gathering here you have never flown the Legacy. You have not even flown the ERJ-135. You managed to watch people who did fly it and perhaps talk to them. I am not sure that is a rational basis on which to judge an airplane that has had roughly a decade of development since those early certification days (in the case of the Legacy I believe it has had five years to mature and grow, so the airplane you saw on the ramp is not necessarily the airplane being sold right now).

There is a difference in the design philosophy between airplanes like the Legacy and design built corporate jets like the Gulfstream. In 1995, when Embraer was looking to Gulfstream as a risk sharing partner to help them build their first regional jet, I took their Vice President for Production on a plant tour. When I had his head up in the wheel well on a G-IV looking at the 5/8 th's inch thick wing plank, he uttered, "We couldn't afford to build an airplane like this, we'd go out of business!" When I asked what he meant, he explained, "The Embraer line is built to deliver the lowest passenger seat mile cost possible." What this means is that they build an airplane to the minimums, that is to say that if a Gulfstream component is required to withstand 2.5 G's the company builds it to take 4.0; Embraer would most likely engineer it to take 2.48 G's and allow for rounding because in order to remain competitive in a fierce market place, they cannot afford to carry around extra weight that isn't passengers. No company building corporate jets has to withstand this kind of market pressure when determining how sturdy their jet will be.



Gulfstream determined that the aircraft that Embraer was going to build was inconsistent with the Gulfstream design philosophy and declined the offer.



During ERJ-135 FAA certification, the FAA test pilots would come up to the Customer Lounge right in front of Gulfstream Flight Test to brief and debrief the flights with the Embraer test pilots and flight test engineers. So yes, I heard a lot, but pilots also talk among themselves and test pilots are an amazingly candid group when talking among themselves. For instance the first time I met a Dornier 328 factory test pilot I asked him about the Envoy 3 and he had no problem telling me that it was a POS that was only good for Mach 0.64, FL350, and 1200 nm. When I flew with the FAA test pilots in the Gulfstream, they would talk about their challenges in the ERJ-135 program, just as I’m sure they talked with the Embraer test guys about the Gulfstream and how easy it was to accidentally exceed the speed of sound when doing runaway trim certification.


One of the conversations we had while flying concerned the aeroelastic stability characteristics of the ERJ-135 and how they arrived at the Mach 0.80 Mmo. Let me
show you the regulatory requirements and then I’ll tell you how the speed limit was determined.

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 Gulfstream 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. Here’s the albeit simple math- 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 point is that I didn’t have to fly a closed-loop handling qualities evaluation of the ERJ-135 in order to get reasonably detailed information about it.

By the way, every GV/G550 is flown to Mach 0.92 on Production Test Flights and Completion Test Flights. The FAA required us to take the first 25 to Mach 0.955. The GIV/G300/G350/G400/G450 are flown to Mach 0.90.


[font=&quot]The Legacy is the same type certificate as the ERJ-135, it is the ERJ-135BJ. And yes, I’ve watched it grow. I’ve watched it grow vortilons and poorly engineered winglets which disrupted airflow and introduced yaw instability requiring the installation of ventral strakes. I also watched it grow fuel cells in every imaginable region of it’s wing and fuselage in order to make it’s range guarantees. I also watched them decide to run the AE 3007s a little hotter to squeeze some more thrust out of them.
[/font]

The airplane, being an airliner, was certified to fly anywhere from 2400 to 3600 hours per year. I am not sure that any airplane capable of doing so with the dispatch numbers the ERJ fleet posts could possibly be labled fragile.

The ERJ-135 and all Gulfstreams were certified under FAR Part 25 Airworthiness Standards:Transport Category Aircraft which establishes certification standards for all transport category aircraft. Although the regulation is quite extensive, there are no anticipated flying hour requirements. There are, as I suggested in my first paragraph, different approaches to meeting the FAA certification requirements. For instance the GV encountered a control reversal at Mach 0.955 (rudder CL Beta went positive). The FAR defines a control reversal as a limiting speed and requires that you back off Mach 0.07 from the speed at which this event occured in order to establish Mmo; so in the case of the GV Mmo became M 0.885. The FAR gives you the option of backing-off only Mach 0.05 if you can demonstrate equivalent safety through rational analysis, which is the approach Bombardier used in establishing Mmo for the Global Excess.

In discussions with a friend at Flight Options amon others I am told there are four configurations for the Legacy and that only the first early prototype numbers were posted to C&DD. Embraer has, apparently, and to their detriment, not bothered to correct the data that C&DD shows. I also noticed a Legacy for sale being advertised using C&DD data and it was a serial number down near the 500 range. Embraer already has nearly 850 ERJs and Legacys flying around the world, so it seems clear that C&DD is using old numbers that could have changed since 2000 (the year of the ERJ I saw for sale online).

Conklin and DeDecker is a competent organization and uses current product information (it is updated twice annually in Spring and Fall). To do otherwise would open them up to litigation as clients use their data to determine which aircraft to buy and of course they would lose customers such as Gulfstream and Cessna. The Cessna website even refers you to Conklin & deDecker to acquire the DOC for Cessna products.


GV







~

 

[GVFlyer]

WSCoD

Again, I am not trying to become and advocate for the airplane by any means, but it seems quite clear that it is not the flimsy toy you claim it to be. It's not a Gulfstream, but it isn't meant to be. I don't particularly see anything wrong with that.

I think two of the primary factors in determining the sturdiness of an aircraft are the length of it's warranty and the TBO for it's engines. The Gulftsream has a 20 year warranty on Primary and Secondary Structures, the Legacy is warrantied until end of your fifth year of ownership. The TBO for the Gulfstream's Rolls Royce Tay MK611-8C is 12,000 hours. The Legacy's AE3007 A1E's are TBO'd on condition but are lucky to make 6,000 hours.

As for contacting C&DD goes, I doubt it would be interested in taking unsolicited data from someone about an airplane it cares nothing about - assuming I was willing to spend the time to do it.

Actually they are very receptive to input from manufacturers once you have established your Bona Fides and the veracity of your claims.

Also, how is a G350, with twice the thrust, twice the weight going to operate for the same cost as the Legacy? Just doing numbers in my head shows that the Legacy burns 325 gallons per hour vs. 450 gph for the Gulfstream 350. Also a window on a G I am told costs about 50,000 to replace compared to about 5,000 for the EMB. Assuming this is even remotely accurate, how can the G350 even come close to the same operating costs? It seems to defy physics for an airplane twice as heavy to run at the same rate as the comparative jet.

A comprehensive warranty plays a role here, but this is how Direct Operating costs are determined:

Direct Operating Costs assume the following:
- Maintenance labor ($79.00/hr), parts, engine reserves, and miscellaneous flight expenses.
-Fuel burn based on a 1,000 nm mission with 8 passengers.

DOC for the G350 is $1731 /hr.
DOC for the Legacy is $1615 /hr.

Keep in mind that Long Range Cruise for the G350 is over 8% faster than the Legacy while the 71,300 pound G350's hourly DOC is only 7% more than the 49,758 pound Legacy's. So actual operating costs are about a wash.


GV

 

[semperfido]

bump

 

[some_dude]

GV, great posts!

 

[ERJ-140]

So far this has been a great discussion. I am finding it hard to believe I am still talking about an airplane I have never flown (for the record, flew RJs for AE).
I applaud your knowledge GV but I have to call "b.s." on ya'!

The Legacy is the same type certificate as the ERJ-135, it is the ERJ-135BJ.

Yes, but even the 135 has evolved. The oldest models we had were not as good as the newer ones. Embraer made signifiacant changes to all three RJ versions, adding fuel, thrust, changing cockpit, improving fadecs, etc.). The 135BJ has gone through a similar evolution.

And yes, I’ve watched it grow.
I’ve watched it grow poorly engineered winglets which disrupted airflow and introduced yaw instability requiring the installation of vortlons and ventral strakes.

This is the part where your knowledge hole appears. The airplane had vortilons from day one. The winglets were not added until nearly a decade later.

As for the engineering goes I can't comment. The winglets must do something or they would be gone. It is probably hard to mate winglets after the fact so some concessions have to be made. I think the strakes look cool any way.

I also watched it grow fuel cells in every imaginable region of it’s wing and fuselage in order to make it’s range guarantees.

Another BS call on you here. The wing tanks are the same as the LR (the Legacy actually claims a slight reduction in wing fuel from the LR). The fuel tanks in the fuselage don't seem too complicated: one bisected fwd one bisected aft. Grand total four fuse two wing tanks.

As for Embraer vs G design philosophy, take a llok at what it was built to do. Embraer told its customers it could deliver 2000-3000+ hours per year and lots of cycles with high reliability. That is what it was made to do and is doing. I cannot call that fragile. In fact, it may be overbuilt for the corporate world (we might be lucky to fly our Falcon 500 hours a year and we don't do five legs a day - what are FLOPS' Legacys doing? Three, four times that?). Also, as one pointed out earlier, have you seen the landing gear trunion/strut on a Legacy/ERJ? That thing is beefy! Hardly fragile.

Gulfstream is wonderful, but it sounds like they are a lot less efficient than they need to be if they are as overbuilt as you say.

C&DD may be a reputable organization, but I have to go with the people flying the airplane who tell me what Volumes 1 and 2 of the AOM say. C&DD are a little behind the ball.

Also, forgive my ignorance, but would the Legacy delay flutter with a boosted elevator?

 

[O-Line]

Hey Skull-One/LegacyIIDriver, do you really think you're fooling anybody?

 

[G100driver]

GV, great posts!

I must agree. It appears you have a great handle on this ..... vs that unfortunate Aurther Q comment.

I always enjoy reading your informed well thought out retorts. I always learn something new. Thank-you.

 

[ERJ-140]

I must agree. It appears you have a great handle on this ..... vs that unfortunate Aurther Q comment.

I always enjoy reading your informed well thought out retorts. I always learn something new. Thank-you.

This is the frustrating part, however, and that is that the man can make mistakes about the airplane that are obvious even to a lowly former-RJ driver but the crowd still cheers. People are not being objective in this debate, they are simply taking the side of a guy they like even when he is wrong (perhaps rarely, but still not infallible). Try to read what is being said by both sides and call a spade a spade.

 

[G100driver]

This is the frustrating part, however, and that is that the man can make mistakes about the airplane that are obvious even to a lowly former-RJ driver but the crowd still cheers. People are not being objective in this debate, they are simply taking the side of a guy they like even when he is wrong (perhaps rarely, but still not infallible). Try to read what is being said by both sides and call a spade a spade.

LegacyDriver ... how nice it is to have you back. That NetJet Strike post was threatening to talk over as the highest number of post on the FI message board. I look forward to watching this .... again.

Really, it is nothing personal, it is just fun to watch