Sunday, July 02, 2006

Eclipse Takeoff Performance

Quoting from the Eclipse website, "This jet performs - even at higher altitudes and temperatures - were talking Telluride, Colorado (elevation 9,078 feet) in July."

Let's peel the skin off this onion by first looking at the certification basis for the Eclipse. Part 23 of the Code of Federal Regulations, Section 14.

One should note that Part 23 rules do not cover range or fuel flows. When a manufacturer publishes this data, it is not verified by the FAA even though it is published in the FAA Approved Flight Manual. Accuracy of the data is solely at the risk of the company's reputation and future legal responsibility.

Takeoff and landing distances are another matter. These numbers are determined by specific methods and must be verified by flight tests. Stall and climb speeds fall into this category. When published in the Flight Manual, this data is FAA validated and approved.

Part 23 certification applies to aircraft weighing less than 12,500 lbs. Takeoff distances are based on both engines operating and climbing to 50 ft above the runway. Eclipse has given no indication they are deviating from the basic requirement.

Aircraft weighing above 12,500 lbs are covered by Part 25. Takeoff distances are based on an engine failure during the takeoff run. The available runway must be sufficient to either continue the takeoff on one engine and top a 35 ft obstacle at the end of the runway or abort the takeoff and stop before the end of the runway.

The bottom line for Part 25 procedures, lose an engine on the takeoff run and the pilot should be able to handle the emergency. All other certified business jets and all commercial airliners operate to this standard. Even the Cessna Mustang, which will certify to Part 23, is basing their takeoff data on the Part 25 loss of engine criteria.

When Eclipse makes the claim their airplane can legally takeoff where perhaps no other jet can legally takeoff, it may be true, but not with the same safety margins. Lose an engine on the Eclipse halfway down the runway at Telluride and the results may be catastrophic!

Writing this makes me feel a bit hypocritical. In 1977, Learjet's V.P. of domestic marketing wanted to fly Jack Eckerd (owner of a chain of 1,500 drug stores in the Southeast) and three of his friends from Aspen to St. Petersburg, Florida. With a combination of the fuel to fly the trip non-stop, the temperature, Aspen's elevation and runway length, the flight could not be flown within the Flight Manual limitations. The domestic pilots refused the mission, so the V.P. turned to the international marketing department's pilots, Jim Bir and myself.

While there was no way to make a legal takeoff, we determined that by changing procedures, we could make a safe takeoff. This included added stopping power from the drag chute which is not counted in the Flight Manual numbers and reducing pilot reaction time for braking and spoiler deployment. We determined we could accelerate to the V2 speed on the ground (speed at which the airplane will fly on one engine) and if we lose an engine, the spoilers, brakes and drag chute would get us stopped before we ran out of concrete.

On the appointed Sunday afternoon, we had a shiny new Learjet 35A on the ramp in Aspen. Jack shows up with his party, we board and launch for St. Petersburg. The takeoff was uneventful, neither engine coughed. My well rehearsed co-pilot duties were to call the airspeeds, monitor the engine gauges, keep one hand on the drag chute handle and suck the gear up on rotation.

We left a Cessna Citation sitting on the ramp, the crew waiting for nightfall and cooler temperatures so that they could fly nonstop to Baton Rouge, LA.

Jack bought the airplane, our V.P. of domestic marketing was happy but the flight was an unethical demonstration for which I regret today. We put Jack's future pilot in a spot. If Jack wanted to make the same trip, how could the pilot explain that he could not do what the factory pilots had done.

But that was not the only time Jim Bir had flown outside the Flight Manual. In the early 70's, he flew the President of Ecuador out of a shorter runway than what the manual would allow.

Several months later, I stood before the Ecuadorian Minister of Defense and his military tribunal accused, on behalf of the company, of endangering the life of the president. Eventually the charges escalated to attempted assassination of their esteemed leader. The whole story can be read at:
http://www.aerotalk.com/Lear_Ecuador.cfm

There is a plaque that hangs in many areas frequented by aviators. It reads, "There are no old, bold pilots."

Such it was with Jim Bir. He took a new Learjet 55 to South Africa for demos. Just after lifting off at a small airport, he intended to roll the aircraft which we had done many times in 24s, 25's, and 35's. The 55 did not behave like the earlier aircraft and he augered in. His remains were cremated and sent home in a small stainless steel tube. I was pall bearer at his services.

We had flown together in the U. S., Europe, Japan, China, Australia, and all over South America and had shared a lot of adventures. But his death was sobering and I lost interest in driving airplanes.

16 comments:

flight guy said...

The article today in Aviation Internationl Online completely supports your supposition. In addition, the range numbers are worse than published with some TBD aero fix for aircraft 101 and greater. As far as certification goes in the weeks to come, don't the engines have to be certified in Canada first as outlined before they can be certified by the FAA? I haven't heard any hints that the engines are close to being certified in Canada. Coming weeks very well may be coming months.


Eclipse 500 by the Numbers:
Eclipse Aviation has released the final performance numbers for the Eclipse 500, and it meets or exceeds all of the guarantees but one. Critics missed the mark that the very light jet couldn’t meet its high-speed guarantee—Eclipse says the VLJ’s top speed is 370 knots, well within the margins. And when it comes to useful load, the aircraft will deliver 2,400 pounds, some 200 pounds more than promised. However, the airplane comes up 130 nm short of its 1,280-nm estimated NBAA IFR range (four occupants, 100-nm alternate). In fact, the first 100 airplanes will come up even shorter, with a range of 1,050 nm, according to Eclipse president and CEO Vern Raburn. “Serial number 101 and on will have some kind of aerodynamic cleanup and/or modifications to reach the 1,150-nm NBAA IFR range,” he told AIN. Since the original range guarantee wasn’t met, customers have the option of canceling their order without incurrin! g any penalties. “So far, only two customers have asked for their deposits back,” Raburn said. FAA certification of the Eclipse 500 has slipped beyond the anticipated goal of last month and is now expected in nothing more definitive than “the coming weeks.”

Stan Blankenship said...

flight guy,

Thanks, I had not seen the AIO article.

As far as the critics "missing the mark," a jets maximum speed comes at a lower altitude where maximum Mach number intersects the maximum indicated airspeed limit. This is sometimes called the knee.

The knee for the Eclipse is probably around 30,000 ft. I do not question the airplanes ability to fly the red line at FL 300 although you would be looking at higher fuel flows and reduced range.

The famous Phoenix to Chicago leg that Eclipse used to claim was based on cruising 370 knots at FL 410. Can the airplane cruise at 370 knots at FL 410? I do not know and Eclipse is not saying.


When Vern claims the 1,150/1,050 nm range, he is not telling us at what speed nor the cruise altitude.

What happened to his program of transparency?

I believe you are right on Canadian certification although there is probably a lot of reciprocity between the FAA and Canadian authorities.

Stan Blankenship said...

Correction:

Eclipse Vmo = 285 kt

Eclipse Mmo = .64 Mach

This puts the knee closer to 22,000 ft.

If you fly the red line at 22,000 ft, the airpeed indicator will read 285 kts, the Mach meter .64, the maximum true air speed should be closer to 390 kts.

Fly the mission at 22,000 ft and the range will be severely limited.

flight guy said...

Where would an airframer go from here if the numbers are so far off the map in regards to cruise performance? Would any potential aero mods get him there? I have my opinion, what's yours?

Stan Blankenship said...

flight guy,

The answer to your question is the subject of my next blog post which I will write when I find the full text of the AIO article. Is it in the AIO subscription area?

As a sneak preview though, I will tell you in the case of the Eclipse, it may involve getting rid of the tip tanks and adding wing tip extensions.

There are a couple of things that just do not add up and I would like to discuss these in more details.

OK, that is my theory, what is yours?

Stan

flight guy said...

To me it would appear from the outside looking inward, that the engines are underperforming and the specific fuel consumption is drastically greater than earlier thought. That is the reason the tip tanks were installed as a "band-aid fix." However, the engines are very likely out of spec greater than anticipated even with the modifications.

I would agree that the fix would obviously be more stored fuel on board. Which is why I would presume that you are looking at wing mods in addition to the additional lift performance in wing loading. However, as you know this comes at a cost. The outcome is increased fuel airframe weight, which has a performance impact.Thereby negative speed and time to climb impacts.

The AIN Online article was e-mailed to me directly. It should be on their website at this time.

Stan Blankenship said...

Raburn has always been quick to point an accusing finger at non-performing or under-performing vendors and he is not saying he has a problem with Pratt. Which is not to say he does not have an engine problem.

They may need to extract more bleed air for pressurization than what was originally planned or allowed for by spec.

Pratt should have excellent computer models to predict engine performance even though the 610F was so small it may have been off the charts.

Back to Vern's statement, he is saying aerodynamic cleanup and\or modifications. Eliminate the tip tanks and add 2-3 ft/side of wing extension would increase the aspect ratio, enable it to reach higher altitudes, reduced fuel flows and maybe even lower the deck angle during cruise... Think U-2.

If he can reduce drag and fuel flow, they will not need any more fuel to increase range.

Structurally, the airplane is overbuilt. It sailed thru static test with no failures. Wing extensions will shift the center of lift outboard and increase bending moments at the wing root. I suspect strain gage readings during static test will tell them they can make the mods without a big weight penalty.

This is all speculation of course. Vern is talking a significant drag reduction and it will take more than tweaking wing fairings and the like.

unsafe@anyspeed said...

Stan and flight guy,

I can't find this article online yet, when was it supposed to be posted?
I have talked to some friends along the way and they said from the beginning that there was no way that the Williams engine could power this plane. They had to go to the Pratt engine to get the thrust they needed. One rumor was that they picked the Williams before they went to the tunnel, can't verify that. After they picked the Pratt, the guys said that they would either make speed or range but not both.

Stan Blankenship said...

unsafe,

Like you, have yet to locate the AIO article. Also nothing on Vern's website to suggest they will make major mods after unit 100.

Watching to see what news Eclipse will be release at Oshkosh this week...

Thanks for reading the blog and the comments.

flight guy said...

After noticing that you guys have a problem locating the article. I went online to locate it for you. To find it got to:

http://www.ainonline.com/index.html

click: Publications Tab
click: AIN Alerts (email that I received)
click: Check out sample issues (Assumes your not signed up)
click: July 6, 2006

The article is "ECLIPSE 500 BY THE NUMBERS".

Hope this helps.

Stan Blankenship said...

flight guy,

Thanks, the path worked fine.

Have not seen this info published anywhere else, certainly not on the Eclipse web site where they only publish good news.

Equally interesting, was the AIN article on Sino-Swearingen. Nine months after certification, they hope to deliver the first SJ30-2.

S-S has been involved in a 20 year epic struggle to bring this airplane to market. Like the Eclipse, the money spent in development amounts to a lot of green backs that may never be recovered.

The company went through a lot of staff turnover, lost a test pilot during testing, but they persevered. No flash, no razzle-dazzle, no egocentric management.

I wish them success and hope they sell lots of airplanes.

flight guy said...

Looks like Eclipse will receive a provisional TC for the E500 today. PWC just received their Type Cert in Canada. With the provisional they still can't make customer deliveries like earlier rumored, although a ceremony with the first customer will probably take place.

flight guy said...

As previously stated by AIN, Eclipse is not meeting their range requirements. They are proposing to add even larger aluminum tip tanks as the retrofit to meet the 1125 nm range.

Attached is the clip from AIN Alert that I recieved.


Eclipse 500 Gets Provisional FAA Certification
Vern Raburn, president and CEO of Eclipse Aviation, was flanked by some 200 company employees this afternoon at EAA AirVenture in Oshkosh, Wis., to announce provisional FAA certification for the Eclipse 500. “We have proved all the naysayers wrong,” he said. This marks the first agency approval for a very light jet, though the current certification is with “significantly reduced avionics functionality,” according to Raburn. He further revealed that Meggitt had “tremendous” problems getting the autopilot ready and said he expects the twinjet to receive full type certification late next month that will allow day/night, VFR/IFR, single-pilot and RVSM operations, as well as the start of Eclipse 500 deliveries to customers. Eclipse also said it will change the tip tanks from composite construction to aluminum, increasing their fuel capacity from seven gallons to 19.5 gallons per side. The NBAA IFR range at high-speed cruise with the original tip tanks is 1,055 nm, but increases to 1,125 nm with the new tanks. However, Raburn said, “We guaranteed 1,280 nautical miles and we’re not going to meet that.” On the plus side, the small jet’s high-speed cruise is now 370 knots, and Eclipse holds orders for more than 2,500 copies of the Pratt & Whitney Canada PW610F-powered twinjet. The PW610F received Transport Canada approval this morning, with FAA certification expected within three weeks.

Stan Blankenship said...

flight guy

Thanks for the update, spent Saturday at Oshkosh and will write more later next week.

Vic Dickerson said...

Jim Bir and the Lear 55 was a hot and high problem. There was lots of runway. Jim rotated the 55 rolled it on its back and pulled it through. came out level then hit the dust going in the oposite direction and very near to where he started his take off. Waterkloof airfield is at about 5,000 ft and the day was around 27 C.

Stan Blankenship said...

Vic,

Not sure where you are coming from but I have discussed Bir's accident with both Jerry Baker and Frank Schick again in the last twelve months.

Both investigated the accident in S. Africa. Baker on behalf of the FAA, Schick as Lear's accident investigator. Frank was my college roomate; he and his wife just happened to be my house guest this weekend.

Their opinion and mine (having flown with Jim all over the world), was that he attempted to roll the airplane after breaking ground. It is a maneuver we (me in the right seat) had done in both the 20 and 30 series aircraft several times with no problems.

Try it in a M55 and the results will not quite be the same as Jim learned the hard way.

I have a copy of the accident report in my desk and will be happy to share it.