Legacy Bashfest - Bring it on!

[GVFlyer]

WSCoD

Originally Posted by GVFlyer

The strakes on the Legacy empennage and the vortilons on the wing leading edge were installed to compensate for yaw instabilities occuring as the result of adding poorly engineered winglets to the EMB 135 wing in an attempt to extend the range of the Legacy.

GV

You are definitely wrong here. The strakes were added because they allow us to dispatch WITHOUT a yaw damper. Without them the damp would be required due to the winglets.

And this differs from what I said in my post exactly how? Yaw dampers are installed to compensate for yaw instabilities such as Dutch Roll and aerodynamic anomalies such as those generated by the winglets on the Legacy.

The vortilons are to energize airflow over the ailerons at low airspeeds (since we don't have roll control spoilers). It's a matter of doing the smart thing and the drag penalty is apparently not enough to matter or they would have done something else I am sure.

Ordinarily, I would agree with you. The GIV has vortilons because a certain test pilot named Lee (AKA Torch, but as the resultant of another incident) managed to get a GIV to roll-off at low speed and high angles of attack on an approach during GIV developmental test. During G450 development, I flew a white GIV named "Casper" doing flow visualization and drag reduction tests. Casper had the vortilons removed and I didn't miss them. I suggested that since Lee was gone and there was no further risk of him flying our aircraft, that the vortilons could safely be removed from the rest of the GIV's, but my pleas fell on deaf ears.

I am sure that the vortilons on the Legacy assist in reducing spanwise flow and increase control surface effectiveness at high angles of attack as they do on the GIV, but I am also sure that they they perform an additional duty to add increased directional stability (remember that directional stability refers to the behavior of the aircraft in yaw).

Remember also, that Legacy certification was done by the FAA's Atlanta Aircraft Certification Office, the same office that did certification for the Gulfstream GIII, GIV, GV, G550, G450 and G350. A certain amount of shop talk occurs among test pilots who work aircraft certification, whether they work for the FAA or an airframer. I was told that the vortilons on the Legacy assisted in providing directional stability.

This comment is further supported by the remarks of Embraer factory pilot, Marelo Romanelli to Aviation International New's Robert P. Mark during a written and flight review of the Legacy conducted by the magazine:

Strakes have been added beneath the rear fuselage and vortillons beneath the leading edge of the wings to increase stability, especially because of the yaw produced by the winglets. Although the ventral strakes do detract somewhat from the aircraft’s clean lines, they make up for it in dispatch reliability, since the strakes can negate the need for a yaw damper on the MEL list for short periods.


By the way, LegacyDriver, you are always refering to how "rugged" the Legacy is and how no business jet could stand up to the cycles that the Legacy endures in it's true role as a regional airliner. If this is the case, why is the Legacy fuselage only warrantied for 5,000 hours or five years while the Gulfstream's Primary and Secondary structures are warrantied for 20 Years with no hour limitations?

It seems like Embraer doesn't think the Legacy is going to last either...



GV










~

 

[LegacyDriver]

If that is not a DIRECT quote from Romanelli then I would consider it apocryphal. Magazines get lots of things wrong in the translation.

Direct your other questions to EMB since they are above my pay grade.

 

[CatYaaak]

If that is not a DIRECT quote from Romanelli then I would consider it apocryphal. Magazines get lots of things wrong in the translation.

Direct your other questions to EMB since they are above my pay grade.

WSCoD Driver, you are SO out of your league and weight-class debating with GVFlyer at every level you've tried here, it ain't even funny....well, actually it's funny as he11! He knows more about your aircraft than you do, and you know absolutely nothing...nada..zilch...about his, let alone the Challengers and Falcons that can also eat a WSCoD's lunch (and for a lot fewer dollars).

Hey, are you gonna answer his question regarding life-limits/durability on your respective aircraft?.....or will you once again avoid, evade, deflect, and ignore that one too in your effort to gloss-over the WSCoD's deficiencies and sub-par performance? After all, YOU'RE the one who made the original claim (STILL unsubstantiated after a zillion posts) that "no way is a Gulfstream as durable/reliable as a Legacy".

C'mon boy, back it up! Or are you just going to tell us how you "feel" again?

 

[AA717driver]

This thread needs a visit from Dr. Kevorkian...

GV tried to be nice early on but he pulled out the big stick and WSCoD driver has been vanquished! TC

 

[banned username 2]

WSCoD driver has been vanquished!

i.e. Skull-One

 

[SPBRIAN]

http://www.airliners.net/open.file/709773/M/

You know you are in trouble when even the peeps over at airliners.net are pointing out the obvious. WScoD forever!! This thread is hilarious, long live the entertainment value.

-Brian

 

[GVFlyer]

http://www.airliners.net/open.file/709773/M/

You know you are in trouble when even the peeps over at airliners.net are pointing out the obvious. WScoD forever!! This thread is hilarious, long live the entertainment value.

-Brian

LOL! Great Post! For those that don't want to go to the link, this is what Airliners.net says about the Legacy:

N928CW (145528) One of the largest business jets, yet you can't stand up in the cabin even if you are of average height. What's up with that?




GV

 

[mmmdonut]

jesus..... 21 pages of this **CENSORED****CENSORED****CENSORED****CENSORED**?

 

[CatYaaak]

LOL! Great Post! For those that don't want to go to the link, this is what Airliners.net says about the Legacy:

N928CW (145528) One of the largest business jets, yet you can't stand up in the cabin even if you are of average height. What's up with that?

GV

LIke I said before, the WSCoD is probably a perfect airplane for Willie Wonka's flight department if he needs to shuttle Oompa Loompas between his chocolate factories. It looks like something they'd ride in too.....kind of "Dr. Suess-ey".

 

[LegacyDriver]

Talk about opinions... "Poorly engineered winglets on the Legacy"? Dude, I love how your opinions are considered facts.

I thought this was a rhetorical question since our resident "test pilot" (HA!) should know this. But...

Winglets are designed to be efficient in cruise. In high-AOA and/or low airspeed conditions winglets are not operating in their target regime. All winglets (at least until full-circle winglets come out, and they, too will probably suffer when slow), including those on the G-Whiz, have some tradeoffs for low speed/high AOA conditions. In the Legacy's case it is a stability issue. Hence the strakes. Airplanes from the Learjet and Excel to the F-16 and *GRUMMAN* F-14 have ventral fins and none of those airplanes (with the exception of the Lear, and my recollection is those are there to put the nose down when you get it *too* slow) can blame it on winglets. The Legacy winglets do their job. The improve CRUISE efficiency. Period. Nuff said.

As for cabin height... How much time does one actually spend standing up in an airplane any way? Not much. If we look at our shrinking population (immigration and so forth are just dragging the average U.S. height down--Norway is now #1 we are #2) then the Legacy cabin accomodates over 90+% of the population and as we shrink it will only accomodate more...so let the other 5-10% decide if it is that important to them. Perhaps they need a BBJ.

 

[LegacyDriver]

N928CW (145528) One of the largest business jets, yet you can't stand up in the cabin even if you are of average height. What's up with that?




I'm glad you posted this picture of a LEGACY I. Notice the windshield wipers, non-faired wheels, lack of aileron/flap seals, and absence of forward intake doors, among other things, all of which are significant drag improvement changes standardized on the Legacy II (http://www.airliners.net/open.file?id=721971&size=L&sok=V0hFUkUgIChhaXJjcmFmdCA9ICdFbWJyYWVyIEVSSi0xMzUgTGVnYWN5JykgIE9SREVSIEJZIHBob3RvX2lkIERFU0M%3D&photo_nr=7). At least my "opinion" on these matters is fact.

 

[CatYaaak]

........ The Legacy winglets do their job. The improve CRUISE efficiency. Period. Nuff said.

As for cabin height... How much time does one actually spend standing up in an airplane any way? Not much. If we look at our shrinking population (immigration and so forth are just dragging the average U.S. height down--Norway is now #1 we are #2) then the Legacy cabin accomodates over 90+% of the population and as we shrink it will only accomodate more...so let the other 5-10% decide if it is that important to them. Perhaps they need a BBJ.

My Yak-40 don't need no stinkin' winglets or sissy strakes! It's performance rivals or equals the WSCoD's due to superior collectivist engineering, and not only is it FAR more durable because it's a REAL "real airliner" (unlike your tinker toy-ish Brazilia Spawn), it's also roomy enough for 99.99999999% of people and 99.99999998% of Norwegians to do the Cossack-kick Dance routine including the full-body extention part when everyone shouts "HEY!".

And the Legacyski does all this for far less $$$ than your WSCoD. Period, comrade. 'Nuff said.

"If Lenin's in Heaven,
then unused by his side,
Angel's Wings he was issued.
A Yak-40's his Ride!"

 

[AA717driver]

How much time do people stand up on corporate planes? As often as they want to and they pay big bucks to be able to do so.

The population is shrinking due to immigration. Ok, when those swimming across the Rio Grande start buying large cabin jets, I'll give Embraer a call.

Until then, I'd stick to trying to sell Willy Wonka an airplane...TC

 

[GVFlyer]

WSCoD

Talk about opinions... "Poorly engineered winglets on the Legacy"? Dude, I love how your opinions are considered facts.

Facts are facts. Properly engineered winglets don't introduce adverse aerodynamic qualities that require aerodynamic patches (like strakes) to fix. On the Legacy, the after-the-fact winglets were a trade-off that marginally increased range, but made the aircraft less stable in so doing.

I thought this was a rhetorical question since our resident "test pilot" (HA!) should know this. But...

There are other members of SETP who frequent this board.

Winglets are designed to be efficient in cruise. In high-AOA and/or low airspeed conditions winglets are not operating in their target regime. All winglets (at least until full-circle winglets come out, and they, too will probably suffer when slow), including those on the G-Whiz, have some tradeoffs for low speed/high AOA conditions. In the Legacy's case it is a stability issue. Hence the strakes.

Nicely stated, but your assumptions about the GV/ G550 are wrong. Please advise us as to what you think these trade-offs on the Gulfstream might be. With 30,770 lbs of thrust the jet can achieve extreme pitch angles while maintaining low alpha. The GV has been flown from 74 knots to Mach 1.07 without the need for strakes, vortilons are other aerodynamic patches.

The Legacy winglets do their job. The improve CRUISE efficiency. Period. Nuff said.

It would be, "Nuff said", if the add-on winglets didn't make the Legacy divergent in yaw.

There is a world of difference between a wing initially designed as a straight wing which later has a compromise winglet cobbled on, as on the Legacy, and a wing that was designed to include a winglet.

The 93.47 foot GV wing was developed with winglets by Gulfstream scientists using NASA Blended Winglet Theory on the same Boeing computers that had been used for 777 development. Final development was accomplished at the NASA Langley wind tunnel where the wing was idealized for it's operating environment. It is a technologically advanced design unmatched by any T-category aircraft wing in the industry.

The GV wing was the first application of jointly developed NASA / Gulfstream Micro Vortices Generators allowing a lighter design, greater camber and more interior volume. The entire top surface is a single bonded piece of extruded aluminum using a Vought proprietary process called age creeping. It is an all lifting design including the radius going into the winglet, there are no washed-in or washed-out areas and no stalled regions. The winglets are a NASA design which provide a forward thrust vector. There are no leading edge devices required to provide a minimum Vref of 110 knots or any canoes needed to hide flap gear. The nominal sweep provides benign Dutch Roll characteristics which allow the G550 to be flown at 51,000 feet without a yaw damper. The wing, from it's inception, was designed to be a high speed, high altitude, high efficiency device embodying the latest NASA and Gulfstream technology.

The GV was flown to Mach 1.07 during developmental test with no buffet or adverse Mach effects. Aerodynamic center of pressure moved to 50% MAC and a shock wave formed ahead of the aileron trim tab rendering aileron trim inoperative. Another shock wave formed ahead of the elevators with the same effect, but the all moving tail remained effective for pitch control.

The true proof of a wing design is in how the aircraft performs. The G550 at maximum gross weight, 91,000 lbs., will always initially climb to at least 41,000 feet. 51,000 feet is available for up to the last 3 hours of flight. With 8 passengers, the G550 will fly 6750 nm at M.80, 6500 nm at M.83, 6000 nm at M.85 and 5,000 nm at M.87.

The jet will do M 0.84 at FL490 while burning only 1200 lbs a side. At 51,000 feet the jet can burn as little as 962.5 lbs a side!

As for cabin height... How much time does one actually spend standing up in an airplane any way? Not much. If we look at our shrinking population (immigration and so forth are just dragging the average U.S. height down--Norway is now #1 we are #2) then the Legacy cabin accomodates over 90+% of the population and as we shrink it will only accomodate more...so let the other 5-10% decide if it is that important to them. Perhaps they need a BBJ.

Actually, the most recent anthropometry studies show the US population to be getting taller and heavier. Here's a statistic from that study that will keep you awake at night: "The average woman in the United States is 5"4" tall and weights 164 pounds."

Now, how about answering my question about why the Gulfstream fuselage warranty is 400% longer than the Legacy's.

OK, you give? It's for the same reason the Legacy doesn't have roll control spoilers. The Legacy was designed to be cheap and light. Spoilers would increase complexity, weight and cost. The strength needed to make a jet warrantied for 20 years requires structure which increases weight which increases passenger seat mile cost. The driving force behind EMB 145/ EMB 135 / Legacy development was keeping passenger seat mile costs down and acquisition costs low.

GV

 

[HawkDrvr]

Will this thread PLEASE DIE... LegacyDriver can't get over the fact that his airplane is essentially a polished t%rd.

Trying to compare it to the GV is like me comparing my ever expanding beer gut to Brad Pit's abs. Lets move on...

 

[AA717driver]

The Legacy isn't a polished turd. But it certainly isn't what LD initially asserted in the other thread that spawned this one. The Legacy is not simply a low-cost equivalent to the Gulfstream/Global families.

DOCTOR KEVORKIAN TO THIS THREAD--STAT!!! TC

 

[HawkDrvr]

Love the new Avatar man... Was it time to move on from the other woman ???

 

[Ace-of-the-Base]

The GV was flown to Mach 1.07 during developmental test with no buffet or adverse Mach effects.

That was an accident during testing, but still proved the airplane's ability.

Ace

P.S. Man, you write long posts - you must have a lot of spare time.

 

[LegacyDriver]

The Legacy isn't a polished turd. But it certainly isn't what LD initially asserted in the other thread that spawned this one. The Legacy is not simply a low-cost equivalent to the Gulfstream/Global families.

DOCTOR KEVORKIAN TO THIS THREAD--STAT!!! TC

717 I respect that you are at least level-headed and refrain from slurs and slanders, but...

For the "average" Gulfstream IV (450 or whatever) and V mission it *is*. Namely coast-to-coast USA, or USA to Europe, etc.. The airplane does 3200 NM without breaking a sweat for half the price of a Gulfstream (V acquisition, IV and V DOC--and I have yet to talk to anyone in the real world who thinks the V is anywhere close to the Legacy in DOC). For many people (including my boss) it *is* an alternative. That's my point. Alternative doth not mean EQUIVALENT. It is obviously not the exact same airplane for half the money...

You guys either don't know how to read or INTENTIONALLY mis-read every point I make. As I said, the Legacy can compete with just about every airplane in one area or another. It doesn't necessarily compete with every airplane in every area or with one airplane in every area, but there is enough performance and affordability there to make it a viable option in the majority of cases.

 

[LegacyDriver]

I'll give you an answer...

A warranty is a strange thing. If something doesn't break in the near term it is going to last a very very long time. With many products there comes a point where a warranty is more expensive than self-insurance is.

The Legacy warranty is shorter because the Legacy doesn't break and the parts are so inexpensive that there isn't a need for a warranty any way. Meanwhile, since the Gulfstream is a giant, overpriced, flying turd, replacing parts is like having brain surgery--nobody can afford it without insurance.


Also, I do not believe the G-IV was designed for winglets from the get go. Hence, as I stated previously, it has tradeoffs for the envelope outside cruise. In the case of the V I find it *highly* dubious to assert that any wing is as efficient at one end of the envelope as it is at the other. The thought that any winglet is equally adept at performing in cruise as it is on approach is ludicrous at best.

 

[LegacyDriver]

Will this thread PLEASE DIE... LegacyDriver can't get over the fact that his airplane is essentially a polished t%rd.

Trying to compare it to the GV is like me comparing my ever expanding beer gut to Brad Pit's abs. Lets move on...

I hope you are a BAE *Hawk* driver and not a Hawker driver. Talk about a flying turd...

 

[HawkDrvr]

Somebody please, END THIS THREAD...

 

[LegacyDriver]

Somebody please, END THIS THREAD...

Nobody asked you to read or participate. You have the option to ignore it.

 

[banned username 2]

717 I respect that you are at least level-headed and refrain from slurs and slanders.

Now let's see what else WSofDdriver has to say in his VERY next post!

Meanwhile, since the Gulfstream is a giant, overpriced, flying turd, replacing parts is like having brain surgery--nobody can afford it without insurance.

And yet another!!!

I hope you are a BAE *Hawk* driver and not a Hawker driver. Talk about a flying turd.

I guess one can now determine that WSofDdriver has no respect for himself since he couldn't refrain from "slurs and slander"...

Skull-One it is!

 

[GVFlyer]

That was an accident during testing, but still proved the airplane's ability.

You are absolutely right, no test program would intentionally take a sub-sonic design to supersonic speeds. Here's the story.


Under FAR Part 25 standards for certification, factory test pilots are required to first demonstrate a required test point then that test point is certified by a FAA test pilot from the servicing Aircraft Certification Office (ACO). The FAR requires that neither "exceptional piloting, strength or skill" be required to fly these points - this is the part that the FAA pilots demonstrate best. It was with a FAA test pilot at the helm during a test point to demonstrate recovery from runaway trim that we went to Mach 1.07 during GV development.

This kind of unintentional expansion of a jet's flight envelope is common during developmental test and certification programs when the FAA comes to help us out.

It was during Global Express development when demonstrating recovery from unaccelerated aerodynamic stalls with a FAA test pilot at the controls that the jet pitched-up and could not be returned to controlled flight without deploying the stall chute. This is precisely what occurred during Challenger 600 development with the exception that Bombardier test pilots were at both cockpit stations and that they could not get rid of the stall chute after getting the nose down. Subsequently, there was insufficient thrust available for sustained flight and controlability was suspect. Two of the crew were able to bail out and sustained severe injuries. The remaining pilot and flight test engineer perished in the crash. The surviving test pilot now works in the Atlanta ACO.

P.S. Man, you write long posts - you must have a lot of spare time.

No, after 19 years of flying Gulfstreams with Honeywell FMSs my piloting skills haven't improved, but I sure do type fast.

GV

 

[LegacyDriver]

Now let's see what else WSofDdriver has to say in his VERY next post!

And yet another!!!

I guess one can now determine that WSofDdriver has no respect for himself since he couldn't refrain from "slurs and slander"...

Skull-One it is!

Just following your "steaming" example FC.

 

[LegacyDriver]

You are absolutely right, no test program would intentionally take a sub-sonic design to supersonic speeds. Here's the story.

GV

So what's the story on the Citation X then? At MMO they are well within 15 percent of Mach 1.

 

[banned username 2]

Just following your "steaming" example FC.

I'm not the one preaching and then contradicting my own preachings...

 

[LegacyDriver]

I'm not the one preaching and then contradicting my own preachings...

Yes well, my emotion got the better of me this time. I'm simply treating others as they wish to be treated at this point.

 

[GVFlyer]

So what's the story on the Citation X then? At MMO they are well within 15 percent of Mach 1.

The reason you don't intentionally go supersonic in sub-sonic designs is because the design rules for aircraft intended to be flown in compressible air flow are different from those designed for operation in non-compressible air.

In reference to the 15% you mention, the only requirement that comes to mind is Sec. 25.629 - Aeroelastic stability requirements which requires that when determing VD/MD, a 15% margin is required in an aircraft's height velocity diagram from the point at which flutter is encountered. Note that not all aircraft encounter flutter during certification; the GV's speed limit was determined when it encountered a control reversal at M .955 when rudder CL beta went positive. FAR 25.335 requires that a M .07 margin be established for determining MC when such compressibility effects are encountered. The Global Express used rational analysis to establish the lessor M .05 margin allowed when using that technique, from the aerodynamic event that determined it's limiting speed.

During developmental test you are flying an experimental aircraft and you can do anything with them that you think is required. The Citation X which you mentioned, according to an associate at Cessna, Wayne S., went to M 0.99 during developmental test.

GV