CAPE CANAVERAL, Fla. — In the months leading up to America’s first manned space flight, NASA leaders met for a round table discussion of how to land a man on the moon.
In February 1961, members of the Space Task Group met in Washington, D.C. with engineers to discuss solutions. The group was headed by Robert Gilruth and lead Mercury spacecraft designer Maxime Faget. Wernher von Braun, the father of American rocketry, also attended the meeting.
As the discussion progressed past the midway point, an unknown engineer stood up in the smoke-filled room. He then explained his theory for how America should send astronauts to the moon.
A NASA Engineer’s Cost Efficient, Time Saving Plan For Moon Landing
NASA Langley Research Center engineer John C. Houbolt began to explain an unheard of theory known as Lunar Orbit Rendezvous. His plan would send two spacecraft into lunar orbit, land one on the Moon, and later have the two redock and return to Earth.
NASA engineer John C. Houbolt explains his Lunar Orbit Rendezvous plan in 1961. (NASA)
Houbolt served as Chief of the Theoretical Mechanics Division at Langley, and now he was up to bat in the biggest game of his life.
Lunar Orbit Rendezvous (LOR) was an unknown theory Houbolt had designed five months earlier. He was one of six members of a committee to study problems associated with rendezvous while constructing a space station platform.
In August 1960, the committee began associating the rendezvous of a space station with the rendezvous and landing on the moon. Houbolt used the blackboard to chalk out several designs involving rendezvous for a flight to the moon.
The practical engineer loved the simplest, most cost-efficient method—LOR. As Houbolt spoke of his LOR theory to von Braun and the Space Task Group, it began to fall on deaf ears.
Shouts of “misleading information” from Faget and a head-shaking “no” from von Braun concluded the then 41-year-old engineer’s address to his peers.
Von Braun and several others agreed with a plan known as Earth Orbit Rendezvous, which would see two Saturn rockets launch. One would carry a spacecraft and the other a fuel supply craft into Earth orbit.
The pair would then rendezvous. The Apollo craft would travel to the moon, land, and return as a single craft. Another plan that was being accepted was the direct ascent to the moon.
“The plan was to send a vehicle the size of Atlas to the moon with absolutely zero help and land it backwards,” Houbolt told NASA’s Langley years later, “It can not be done.”
A large rocket, mightier than the Saturn 5, would launch an Apollo craft to the moon. Apollo would then separate in lunar orbit from the rocket and land.
Several weeks after President Kennedy challenged America to land a man on the moon before 1970, NASA administrator James Webb let it be known that NASA was steering Apollo as an EOR mission to the moon, with the direct ascent as a backup choice for landing.
The LOR plan was swept under the rug by a few key NASA managers throughout 1961, except for Max Faget. He began to realize LRO as a better option. Houbolt continued to lobby for his proposal.
Houbolt wrote two letters to NASA associate administrator Robert Seamans asking for support of his plan. By Thanksgiving of 1961, Gilruth and Langley, along with NASA headquarters, approved it as a time—and money-saving option.
A few months later, Von Braun and Marshall approved Houbolt’s idea. Plans were drawn up to build a secondary spacecraft that would land on the moon—the lunar excursion module.
Houbolt single-handedly saved American taxpayers billions of dollars in fuel and rocket costs. He also trimmed the time needed to build the multiple rockets required by EOR by two years.
Kennedy’s challenge survived his presidency. Not just one, but two crewed lunar landings occurred during 1969.
History Also Supported Houbolt’s Plan
Little did Houbolt know that one year earlier, engineers at the Vought Astronautics Division near Dallas discussed their LOR theory with NASA. NASA had also ignored Vought’s engineers.
A few years later, Houbolt learned of Russian mechanic Yuri Kondratyuk, who formulated ideas related to space flight and LOR. Kondratyuk’s designs and notes were made while he was a soldier during World War I. They never reached Russian scientists following the Second World War.
As Houbolt watched Apollo 9 lift off in 1969 with the first lunar module, he felt emotion. His thoughts raced through his own journey and his contribution to America’s space flight.
The Apollo 11 lunar module “Eagle” descends to the Moon’s surface with two astronauts aboard. (NASA)
Two months later, the now-former NASA engineer sat in the visitors’ section of Houston’s Mission Control. Apollo 11 lunar module Eagle had just left lunar orbit to perform the first landing by Neil Armstrong and Edwin Aldrin.
“When the landing took place and the touchdown was made, all of us stood up and started clapping,” Houbolt recalled during a NASA interview. “But at the same time, we were shh, shh, because we didn’t want to miss a fraction of a second of history being made.”
Houbolt added, “Von Braun sat in front of me, and he made the OK sign and said, ‘Thank you, John.’ That was one of the biggest rewards I’ve ever had.”
(Charles A. Atkeison reports on aerospace and technology. Follow his updates via social media @Military_Flight.)
Back in 1963, a Lockheed KC-130F Hercules tanker conducted a series of test landings and takeoffs from the deck of the USS Forrestal (CVA-59). The crew made 29 touch-and-go landings, 21 full-stop landings (Look Ma- No Hook!), and 21 unassisted takeoffs (deck-run takeoffs without catapult assist) while weighing from 85,000 pounds all the way up to 121,000 pounds.
The only modifications made to the airlifter were to the nose landing gear bay, removal of the underwing refueling pods, and beefed-up anti-lock brakes. Even though operating Herks from carrier decks proved to be impractical and somewhat dangerous, the fact that the mighty Herk could even accomplish such a feat (multiple times) is a testament to the ruggedness of the C-130.
The Incredible Versatile Herk
WATCH: A KC-130F Hercules Operates From an Aircraft Carrier Flight Deck 6
Herks have flown into hurricanes and typhoons to gather storm data, controlled all manner of aerial drones, flown airborne early warning and control, electronic eavesdropping, and jamming missions, and inserted and supported personnel behind borders and enemy lines by flying we-were-never-there, nap-of-the-earth ingress and egress routes.
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C-130s do aerial firefighting, recover spy satellites and their “take”- there are even Hercules tankers that can be converted to gunships on the spot and back again after mission completion. C-130s have been flying for the United States Air Force, Navy, Marines, and Coast Guard for more than 60 years and they’re still going strong.
WATCH: A KC-130F Hercules Operates From an Aircraft Carrier Flight Deck 7
American Airlines Flight 1572 could have ended in disaster
Can you imagine wondering if the next minute of your life is your last? Well, 73 passengers and the 5-person flight crew of American Airlines Flight 1572 got to ask themselves that very question the night of November 12, 1995 during one of the most miraculous airline crashes in aviation history.
Flight 1572 was a regularly scheduled redeye flying out of Chicago O’Hare International Airport for Bradley International Airport, located just outside of Hartford, Connecticut. The aircraft in use was a McDonnell Douglas MD-83, narrow-body twin engine jet with over 27,000 hours of flight time under its belt. It was crewed by two pilots, a captain and first officer, and three flight attendants, all of which were seasoned professionals.
Flight 1572 Departed Late Into Challenging Weather
Flight 1572 departed late out of O’Hare at 11:05pm for a relatively short and hopefully uneventful flight to Bradley. However, the weather at Bradley was less than stellar. The field was being pounded by heavy thunderstorms and rocked by gusty winds. Wind shear warnings were in effect and the pressure altitude was changing rapidly.
Enroute, the pilots received an Aircraft Communication and Reporting System (ACARS) weather brief stating the weather at Bradley was quickly deteriorating and the pressure was dropping fast. The ACARS brief also included a barometric pressure setting of 29.40 inches of mercury. This information was important as it would help the pilots make decisions regarding continuing on to Bradley or diverting. Usually, when an updated altimeter setting is received, the pilots update the aircraft altimeter with such. But in this case, for unknown reason, instead of entering the advised pressure setting, the first officer entered an erroneous 29.47 setting into the altimeter.
A Primer On The Importance Of Barometric Pressure
Now…there is nothing sexy about barometric pressure. But, ensuring the aircraft altimeter is set with a current and correct barometric pressure altimeter setting is unbelievably important in aviation. Barometric pressure, or otherwise known as atmospheric pressure, is defined as the pressure of the atmosphere at any point on the earth. It will raise or lower as the outside air temperature changes or when an aircraft makes a significant change in altitude. Barometric pressure is measured in inches of mercury (Hg) and is usually given for a prescribed area. In the aviation world, changes in the barometric pressure affect what altitude is displayed on an aircraft altimeter and is set by the pilots as a deviation from the standard pressure of 29.92 inches Hg. It is important to set the current barometric pressure altimeter setting for an area when flying. Because, if not, the aircraft will in reality be closer to the ground than the altimeter indicates.
Flight 1572 continued on with the pilots prepping for the enroute descent and non-precision localizer approach to runway 15 at Bradley. Enroute descent checks were completed, passengers were directed to take their seats and buckle up, and the flight attendants were directed to prepare the cabin for landing. The weather at Bradley was still terrible, but it was above approach minimums and good enough to continue on to land so the captain reduced power, gently lowered the nose of the aircraft, and commenced the fateful approach to runway 15 at Bradley.
Flight 1572’s approach was more complex than typical but well-within an airline pilot’s capabilities
So…you may be asking, “What is a non-precision approach?” and “How does that play into this story?”
A non-precision instrument approach is designed to allow an aircraft to descend in a controlled fashion from an enroute altitude to a Minimum Descent Altitude (MDA) above known obstacles on axis with the runway so the pilots can hopefully see the runway environment prior to the Visual Descent Point (VDP) which is usually located about one mile from the runway threshold. If the pilots are visual with the runway prior to the VDP, they can descend below the MDA and continue the approach to land. If they aren’t visual with the runway by the VDP then they should execute a missed approach. Non-precision approaches are called just that, as the pilots only have lateral guidance vice lateral and vertical guidance until touchdown. Because, vertical guidance is not provided, the pilots must fly a flat approach until the VDP. At this point the runway is hopefully in sight so they can continue on and descend on a normal 3-degree final approach glide path to touchdown.
These approaches are usually flown with more “hands on” (manual) control rather than auto-pilot or auto-land control and require full attention to maintain aircraft altitude above the MDA. One of the golden rules in aviation is “descent below the MDA is not allowed unless the runway environment is in sight”. Why? Because, it’s unsafe. MDAs are designed to keep an aircraft safely above known obstacles such as terrain, trees, power lines, and towers on final approach so it is imperative pilots fly the aircraft to always stay above the MDA until visual the runway and in a safe position to land.
About five miles from the airport, Flight 1572 encountered heavy rain and turbulence and the captain reported having trouble maintaining altitude and heading with the autopilot engaged. The pilots had also just received communications from the airport tower that it was temporarily closing due to a structural malfunction but would leave one person behind in the tower to monitor communications and the flight during its approach.
The MD-80 That Hit Trees And Kept Trucking, Saving All Aboard 10
Flight 1572 continued its approach and while the pilots peered through the heavy rain for the airport the aircraft inadvertently descended below the MDA and continued on that vector. According to the data captured on the flight recorder, the first officer attempted to inform the captain on several occasions the aircraft was descending below the MDA, and for some reason his altitude callouts weren’t heard, processed, or understood.
Rapidly falling pressure meant aircraft was lower than the altimeter showed
Additionally, the barometric pressure at Bradley had dropped significantly. The tower never passed on any updates and the pilots didn’t ask for any either. Remember, how the first officer set 29.47 before beginning the descent into Bradley? Well, that mistake was seconds from coming full circle as the altimeter had decreased to 29.35 and was falling fast. All indications to the pilots were the aircraft was 120 feet higher than it really was!
At approximately 12:55am, six minutes after beginning its final approach, the aircraft sink alarm blared, warning the pilots of an unsafe descent profile. Seconds later a loud thud was felt and heard as the aircraft impacted a 270-foot swath of tall pine trees along the Peak Mountain Ridge and sheared off the top thirteen feet of tree tops.
The MD-80 That Hit Trees And Kept Trucking, Saving All Aboard 11
“Go, Go Around!”
The captain immediately fire-walled the throttles, but the effect was minimal as tree branches and debris had been ingested into both engines causing them to flame out and fail seconds later. In a last-ditch effort not in accordance with any prescribed procedure, the captain selected 40-degree flaps in attempt to increase lift and gain some altitude. This unorthodox action provided some relief and bought Flight 1572 the few extra seconds needed to fly a bit further so it could crash on the runway rather than in a dense forest of trees just short of the approach end.
However, the heart stopping roller coaster wasn’t over. Both wings were mangled, a gear door had been ripped from beneath one of the wings, and the engines were spewing flames rearward. Just prior to reaching the runway, the aircraft was out of energy and falling like a rock. The pilots were unable to make any fight path corrections leaving the aircraft with only one way to go – straight through the lone tree just shy of the runway and then on further to crash into the runway 33 Instrument Landing System antenna equipment located at the approach end of runway 15. Flight 1572 finally rolled to a stop a short distance down the runway.
The MD-80 Hit Trees But Everyone Survived
Miraculously, all aboard Flight 1572 survived. One passenger sustained a minor injury, while all other 72 passengers and the five crewmembers egressed without harm. The aircraft sustained $9-million in damage and unbelievably was repairable and returned to service a few years later. The National Transportation Safety Board cited the pilot’s failure to level off prior to the MDA as the primary cause for the crash while also faulting the FAA for designing an approach to runway 15 at Bradley that did not take into consideration the terrain on final approach. In the end, a horrific snow-ball scenario that should have culminated in utter disaster, instead was deemed an absolute miracle.
Well, it’s that time of the year again AvGeeks. Whether you are in it for the love of the game, the Xs and Os, because the team of your local metropolitan sprawl happens to be in it, or, speaking for this crew, because of the pre-game flyover (the trifecta of USAF strike bombers this year), it is Super Bowl time. Here’s the story of a pilot turned NFL Pro, Chad Hennings.
Maybe you are inspired by Tom Brady making it to his tenth Super Bowl appearance (like him or not, he is undisputedly the GOAT) or elated by my hometown Kansas City Chiefs’ electrifying performance with their phenom wunderkind Pat Mahomes and his supporting cast. Maybe you’re in it for the beer and chicken wings, which is utterly commendable.
However, we are taking a different angle on the Super Bowl, looking at famous sports crossovers. Perhaps the very most renowned crossover was baseball hall of famer Ted Williams who flew for the Marines in both World War II and the Korean War, which took around five years out of his tremendous playing career. But that is baseball; this is the ultimate day for football.
Famous Football Stars-turned-Soldiers
During the wartime era of the 1940s U.S. Military Academy (West Point) was an incredible winning machine under Red Blaik. Among his crowning achievements were back-to-back Heisman Trophy winners Doc Blanchard and Glenn Davis. Now, Glenn Davis did become a pilot in the Air Force, so he mostly qualifies except he did not play professional athletics.
Photo: US Army
However, I do recall the 1995 Super Bowl quite vividly (Leon Lett should never be able to live down getting his touchdown stripped by Don Beebe). And on that roster was a former A-10 driver.
Chad Hennings: A-10 Pilot Turned Dallas Cowboys Star
While I have always abstained from being a Cowboys fan (Chiefs Kingdom, Baby), as an Av Geek I was very interested in the individual who filled in for Leon while he was doing time on a suspension. Chad Hennings, a 6’6” defensive tackle who was taken relatively late in the 1988 draft by the Dallas Cowboys out of the Air Force Academy (USAFA).
Growing up in rural Eastern Iowa, Hennings was a multi-sport star at Benton Community High School. While he did have several offers, he attended the Air Force Academy, where he initially played tight end. He would later transition to the ball’s defensive side, winning the Outland Trophy in the process, which is no small potatoes.
Upon graduation from the USAFA, Hennings was commissioned as a 2nd lieutenant, where he proceeded to the 80th Flying Training Wing at Sheppard AFB in Wichita Falls, Texas. All of the geeks out there are probably aware that this is home to Euro-NATO Joint Jet Pilot Training (ENJJPT), a highly competitive program.
Back to football. You are probably wondering how Hennings would pull this off, playing in the NFL and flying in the Air Force? Well, he didn’t do it simultaneously. The Air Force was stingy in the late 80’s and denied his request to be released from his service commitment. So he had to settle for merely being a fighter pilot in the meantime.
All jokes aside, this was a serious deal for a good athlete with a career on the gridiron on the line. Football skills are perishable, and he had to focus all of his energy on flying while in UPT.
Hennings Was Too Tall For Most Fighters
Hennings had limited airframe options due to his robust stature (I imagine the T-38 was cramped) and ended up in the Hawg, flying for the 81st Tactical Fighter Wing at RAF Bentwaters, United Kingdom.
Photo: Charles AtKeison
He did not spend all that much time in the seat, although he flew long enough to participate in the original Persian Gulf war. Thankfully for his future career in the NFL, the Air Force began a substantial drawdown after the Persian Gulf conflict ended, and Hennings was able to separate early from his commitment to his commission as a pilot. The rest, as they say, is history.
He went back to the Air Force reserve for a few more years while on the Cowboys’ active roster, but he hung up his wings for good after his stint at Bentwaters. He served in the capacity of liaison to the USAFA until he entered the inactive ready reserve.
Back on the field, he would play sparingly on special teams during his first handful of years but broke out and earned a starting role in the 1996 season. During his time with the team, of which he played his entire NFL career, he won three Super Bowl rings. I’d say no matter how you slice it; he had a pretty successful career.
A 2015 ESPN Sportscenter shared his story in honor of Veterans Day. It’s worth a watch.
UPDATE: Here is video of the official flyover from Super Bowl 55 from the Super Bowl. Next, we share an external video posted by Channel 10 in Tampa Bay. We also included footage from Mike Killian, an Avgeekery contributor below.
Original Story
The Super Bowl is the big game. And each year there is a big flyover before the game at the National Anthem to kickoff the big event. In past years, the Thunderbirds and Blue Angels have impressed the roaring crowds below. We’ve shared videos of the flyovers on our site and even put together a list of the craziest flyovers in the past. Even one where a C-5 saved us from a terrible rendition of the National Anthem. Nothing though compares to this first-ever flyover planned for Super Bowl LV. An ultra-rare dissimilar formation of B-1, B-2, and B-52 will kick off the game this year. What’s even more impressive is that the designation of the aircraft add up to 55 (B-52+B-1+B-2)!
Simulate the big game and the flyover before it happens
The news coverage of the game is notoriously intense. Players are relentlessly hounded for insights and predictions are made. Each year, the Madden Football game also predicts the score of the game. It’s a simulation that is sometimes scarily accurate.
Fast forward to 2021, Avgeeks now have their own high quality simulation tool. They are using it to simulate the flyover for the big game. Just like Madden Football, the quality of the simulation has increased significantly in recent years. Microsoft Flight Simulator 2020 has photo realistic scenery, upgraded flight mechanics, and graphically intense clouds and flight models.
The flyover posted by FlyFS is pretty amazing. They even added timed music to the event. While the real thing will be better, this video serves as a great preview for one of the rarest formations flown by the US Air Force. Check it out and let us know your thoughts.
Not the first time this formation has flown in real life.
Back in 2017, this rare dissimilar formation of B-52, B-1, and B-2 flew for a photo shoot. Our friend, Sagar Pathak captured the unique formation that will be repeated for this year’s Super Bowl.
Sure, for us AvGeeks, these funny things on the wingtips make something cool (a wing) look more cool. For what purpose – and how long have these been around?
Types of Winglets: (Wikicommons)
Surprisingly, two aircraft that I am intimately familiar with participated in the development and use of the Winglets, the KC-135 and MD-11.
KC135 Used at Dryden for winglet test: (Source: nasa)installation of winglets on DC-10-10: (source: nasa)
dr richard t. whitcomb, 1955, testing area rule properties: (source: nasa)
As a 30 year old working at National Advisory Committee for Aeronautics (NASA predecessor), Dr. Whitcomb pondered a recent lecture on transonic airflow delivered by Dr. Adolph Busemann. Dr. Whitcomb, with feet on desk, visualized airplane structures and had the Eureka moment that to minimize drag, the length of aircraft body should be smooth creating the Area Rule.
Chronologically second, Whitcomb’s development of the Supercritical Wing delayed drag onset at high subsonic speeds. This created a more efficient wing eventually reducing fuel costs.
Lastly, and the topic for today, Whitcomb studied the airflow of wing tips for soaring birds. He observed that birds’ wingtips curled upwards during flight. This generated an improvement to the end of wing design that he called Winglets.
PURPOSE
During the Oil Crisis of the 1970’s, Oil prices raised considerably. In 2013 dollars from the following chart, oil went from under $20 to over $100 per gallon.
oil price chart in 2013 dollars: (source: treasury)
Dr. Whitcomb developed the winglet concept to increase fuel efficiency by reducing overall drag. Consider the lift equation below.
Lift equation
Decreasing induced drag at the wingtips increases lift and makes a more efficient wing, thereby saving fuel. Dr. Whitcomb knew that as air moves across and outward along the wingtip, high pressure below the wing seeks low pressure above the wingtip, creating the the wingtip vortices. The installation of a winglet interrupts and decreases the vortices at the wingtip.
What's Up With a Winglet 23
TESTING
Testing began in 1979 on KC-135s at Dryden Test Facilities at Edwards AFB and engineers validated fuel mileage rate increased by 6.5%.
What's Up With a Winglet 24
In the early 1980’s, McDonnell Douglas used a Continental Airlines DC-10-10 to test the performance improvements using winglets. The range and efficiencies increase by 5% and led to full usage within the production of the follow-on MD-11.
MD 10-10 during testing at dryden: (source: nasa)
Nearly all commercial aircraft and some military aircraft use the winglet technology developed by Dr. Whitcomb. As we AvGeeks traverse the skies using inventions developed by seriously smart people, we truly appreciate any extra fuel available due to winglets.
We recently had the honor of talking with Rebeca Palacios Cruz. She is a 31 year old who was a former soldier in the Mexican Air Force. Originally from Veracruz, Mexico, she served as both a Flight Attendant and Air Security Personnel in the Air Force. She recently left the Air Force to continue her aviation career as a pilot.
We Interview A Flight Attendant Who Flew With The Mexican Air Force 33
Studying aviation was my dream, but my most honest answer is because I love the feeling of being literally in the air. I like to be in control of the situation and feel capable of doing it correctly. That is how I overcome my fear of flight. I like the quote:
“Aviation saved my life, now I know who I am and what my purpose is in this world.”
I have many reason why a chose a life in the military. I come from a family with a military tradition. My most important reason though is because I felt the duty to defend the society of my country through the Mexican Air Force. The most gratifying and honorable thing is being able to serve and help through my greatest passion, which is aviation.
We Interview A Flight Attendant Who Flew With The Mexican Air Force 34
I have been a licensed Flight attendant for eleven years, my career began in commercial aviation. I originally flew for ”Magnicharters”, “Interjet” and “Fly Across”, Mexican airlines.
The flight attendant career does not officially exist in the Mexican Air Force, but the function is carried out by airmen. First you are a soldier and then you fulfill the functions of a flight attendant.
We Interview A Flight Attendant Who Flew With The Mexican Air Force 35
The selection is made according to the psychological, cultural, and physical profile as in any armed force. Having the knowledge, license and vocation as a flight attendant is helpful to be selected for the role.
I am qualified in teams: Teams flown in the Mexican Air Force, Mexican Navy, Interjet, Magnicharters and Fly Across.
• Boeing 737-200, 300, 500 and 800.
• Boeing 787.
• Airbus 320.
• Sukhoi Superjet100.
• Embraer 145.
• Learjet 145.
• King Air i350.
• Challenger 605.
• Gulfstream 550.
• Phenom 300.
• Citation Sovereign
• Citation CJ3.
• Legacy 500.
• Casa C295W.
We Interview A Flight Attendant Who Flew With The Mexican Air Force 36
Civil aviation is regulated by the Mexican aeronautical authority (AFAC), where compliance with safety procedures is the most important thing for the flight. As a civil flight attendant, you are in charge of passengers’ comfort with a set schedule.
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In military aviation, the completing the mission is the most important thing. The operations are subject to the needs of the service, so most of the time they are not subject to a set schedule.
That’s right, both in civil aviation and military aviation.
On commercial flights, you usually fly to all the scheduled destinations. On military flights, you fly wherever necessary. With the current pandemic, you’ll fly to support health personnel, transportation of other nationals and returnees along with a host of other operations.
We Interview A Flight Attendant Who Flew With The Mexican Air Force 38
The most challenging part personally is to be able to identify and develop the skills required to carry out air operations. You have a desire to do the best you can while also knowing that the easiest day was yesterday.
In the Air Force, it’s knowing that it’s not about you or oneself, but about something greater than yourself: the welfare of a country—both self-denial and loyalty.
Speaking professionally, it is the constant drive to do my duty with as professionally as possible. That goal drives me to always do well with professional excellence.
We Interview A Flight Attendant Who Flew With The Mexican Air Force 39
I’m not finished with aviation yet. The world of aviation is as big as the sky. I’m working on becoming a pilot in the civilian world. Finishing my pilot training and being able to fly for some humanitarian aid organization and getting into the area of aviation safety are what I want to do next.
I would say don’t hesitate to do it! To be an airman (or air soldier in the Mexican Air Force) you have to take into account that military aviation is an arduous path. It is a system based on discipline, and the values of “honor, courage and loyalty”, made up of by honorable men and women of war.
It is also very rewarding because you will be part of the development and history of a nation. My favorite quote is: “Military aviation is the demonstration of love for the country in aviation.”
We Interview A Flight Attendant Who Flew With The Mexican Air Force 40
Eastern’s Demise Was Painful to Watch No Matter Who You Were
It was the airline that was destroyed by infighting and a soft economy. The airline headed was by World War I ace Eddie Rickenbacker. For a time, Eastern Airlines was known for high quality service with innovative technology. The airline was the first to fly the L1011 and the Boeing 757. Over 60 years, the airline went from one of the ‘big four’ airlines in the US to a failure. On January 18th, 1991, Eastern Airlines suspended service permanently.
What happened to Eastern?
By early 1991, Eastern Airlines had been flailing for a few years.As we previously chronicled, labor relations at the airline were toxic- a combination of challenging management and labor unions that didn’t see eye to eye. CEO Frank Lorenzo was despised by most employees. The labor disputes led to a strike in 1989. This CBS video from 1989 covered the event. Although the airline resumed flying after the strike, the airline never recovered.
Labor and Cash Pressures Doomed Eastern
In addition to difficult labor relations, Eastern also struggled with high debt. The airline flew in markets where competition was intense. The airline also had a mixed fleet of gas guzzling DC-9, 727s and L1011s. When you added in a softening economy brought on by high oil prices due to the Iraq’s invasion of Kuwait, it was a recipe for disaster.
When the airline originally shut down, some people held on to false hope that the airline would somehow resume service with an additional investment of capital. That wasn’t to be. The airline that Eddie founded never flew again. Below is a news report from the day the airline shutdown.
Eastern Returned sorta…Twice
Although the original Eastern Airlines never flew again, a second incarnation flew with the same name beginning in 2015. The famed hockey stick took to the skies on a Boeing 737-800. The airline mostly flew charters with scheduled service from a few US markets to Central American destinations. The airline never rose to the level of success as its predecessor. The most notable aspect of the airline was that it flew Vice President Pence when he was campaigning for office. This second version also ceased service in 2017. Its assets were acquired by Swift Air. Swift then sold the rights to the Eastern name to Dynamic Aviation.
The third iteration of Eastern Airlines took to the skies in 2018. The airline flies a small eclectic mixed fleet of 767-200, 767-300s, and 777s. Today, the airline mostly serves destinations from Miami to the Caribbean and Central America. The airline continues to fly today.
EASTERN SERVES A NUMBER OF DESTINATIONS WITH ITS FLEET OF 767 AND 777 JETS. IMAGE: EASTERN AIRLINES
It has been nearly two years since the 737 MAX was grounded in the aftermath of several crashes. After the redesign of a flight control system, the aircraft has been re-certified by the US FAA and EU EASA and is returning to the skies. Several US and international airlines have already returned their MAX aircraft to scheduled service with others to quickly follow.
One of the requirements for the return to service of this aircraft is that pilots undergo a training session in a simulator. The purpose of the sim ride is to familiarize pilots with the behavior and possible failure modes of various flight control and indication systems. The ride included demonstrations of the normal function of the speed trim system (STS) and Maneuvering Characteristics Augmentation System (MCAS) during a stall and failure scenarios of angle of attack (AOA) and airspeed indicators. Runaway stabilizer trim malfunctions and flight with manual trim were also included. Failures of the MCAS subsystem, which is unique to the MAX, were implicated as contributing causes in two crashes prior to the aircraft being grounded.
Preparation for the ride included an extensive computer based refresher course on MAX systems and procedures and a detailed pre-brief on the planned simulator training events. Flight in high fidelity flight simulators is considered equivalent to flight in an actual aircraft, but superior as a training device as many maneuvers and failure scenarios can not be safely accomplished in an aircraft. That said, the devices cost tens of millions of dollars and training time is scarce and valuable. My airline has procured nine MAX simulators for the purpose of re-qualifying all their pilots in as short a time as possible.
Southwest Airlines plans to return their Boeing 737 MAX aircraft to the skies in Q2 2021.Tomás Del Coro from Las Vegas, Nevada, USA, CC BY-SA 2.0 , via Wikimedia Commons
Stabilizer Trim: What Is It?
The events surrounding the grounding of the MAX center on the stabilizer trim system. I am going to attempt to keep my explanations in reach of a general audience with some basic understanding of the dynamics of flight. There are many online resources available for those who wish for a more in depth explanation of aerodynamics.
The horizontal wing on the tail of a conventional aircraft is known as the horizontal stabilizer (stab). The elevator is attached to the back of the horizontal stabilizer and is a primary flight control. It moves to change the pitch of the aircraft. The horizontal stabilizer itself also moves a bit to “trim” the aircraft for a particular airspeed. Change the speed of the aircraft, and the trim will need to be changed to prevent the pilot (or autopilot) from having to hold constant force on the controls. A pilot can release the controls of a well-trimmed aircraft without it wanting to climb or descend. This condition is also the most aerodynamically efficient configuration resulting in a smaller fuel burn.
On the 737, stab trim is normally controlled electrically by switches on the control column which are activated with the thumb. The switches (two for redundancy) control an electric motor which spins a large wheel next to the pilot’s knee on the center stand. This wheel is mechanically connected to a jack screw which physically moves the stab. The motor has two speeds determined by flap position. The slow speed is used for flaps up and the fast speed activates when the flaps are extended. This wheel also serves as a manual crank to be used if the electric motor fails. Accidentally leaving the crank handle extended is a self-critiquing error as the handle hurts like heck when it hits your knee (so I’ve been told).
It is impossible to miss this wheel turning as it has stripes painted on it. While flying manually (without the autopilot), the pilot will use the thumb switches to activate the electric trim, but when the autopilot is engaged, the autopilot keeps the aircraft in trim using the same system. Therefore, the trim wheel will be seen moving on occasion in automatic flight as the autopilot adjusts the trim.
Starting in the 80s on the “Classic” version of the 737 (models 300 through 500), Boeing introduced a trim subsystem known as “speed trim”. Speed trim would operate in manual flight under certain conditions should the aircraft deviate from the trimmed airspeed. As mentioned above, trim correlates to airspeed. This system would make trim inputs in opposition to any speed deviation to encourage a return to the originally trimmed airspeed. The important thing to note here is that the trim wheel might now be seen moving in manual flight un-commanded by the pilot.
Boeing 737 MAX. Image: Boeing
737 MAX MCAS: What Is It?
MCAS or Maneuvering Characteristics Augmentation System, is another trim subsystem which was introduced on the MAX aircraft. It was found during certification of the MAX that the aircraft had some unwanted handling characteristics when approaching a stall. Specifically, just before stall entry, and well below any normally encountered airspeed, control column pitch forces became lighter when they are required by certification rules to become heavier. MCAS was designed to run the trim forward under these specific conditions to counter this tendency. It uses the high speed rate of the trim motor regardless of flap position.
Why did the MAX handle differently than its predecessors? The aerodynamics is complex, but the larger engines on the MAX had to be placed further forward on the wing to ensure ground clearance. This and other design factors likely caused the handling differences. This is the source of some controversy about whether the MAX should have been given a separate type certificate, but reviewing that subject is not the purpose of this report.
One point I’d like to make about flight control augmentation systems in general is that they are ubiquitous and date back to the 1950s. The existence of an augmentation system does not ipso facto indict the underlying design, but rather is an engineering solution that enhances the flight characteristics of nearly all modern high performance aircraft. I have experience flying aircraft which were virtually un-flyable without augmentation. Even fly-by-wire aircraft flight control systems, which are common today, can be thought of as augmentation systems with 100% control authority.
Lastly, the most important part of the entire electric stab trim system is that it can be deactivated at any time through the use of two stab trim cutout switches located on the center stand directly behind the throttles. These switches remove power from the electric trim system and all subsystems including speed trim, autopilot trim, and MCAS. Following deactivation, the aircraft can still be trimmed by manually cranking the trim wheel.
The MAX Return to Service (RTS) Simulator Ride
Most Airlines now have a dedicated 737 MAX simulator. Photo: CAE
The simulator session was scheduled for a two hour training event preceded by a one hour pre-brief. The session was designed to cover both normal and non-normal flight profiles. The normal profile included a demonstration of the speed trim system on a routine departure and the expected annunciations and flight control behavior during an approach to stall.
The non-normal profiles demonstrated trim system failures and angle of attack (AOA) and airspeed indicator failures. The trim system failures included the use of the Runaway Stabilizer non-normal checklist and immediate action items, and subsequent flight using only manual trim. The AOA and airspeed failure profiles were designed to replicate the startle effect and confusion that can manifest from multiple annunciations and aural warnings during this type of malfunction. Subsequent use of the Airspeed Unreliable non-normal checklist and known pitch and power settings were required.
The simulator used was a CAE 7000XR series high fidelity simulator with full motion and daylight wrap-around visuals. All of the training events were flown from SeaTac airport in VFR conditions. The sim was initialized for takeoff on RWY 16L with all preflight items having been accomplished. I was paired with a line first officer for the training event.
Speed Trim Demonstration
A normal takeoff and RNAV departure to 10,000 ft were accomplished. During the climb in manual flight, deviations from trimmed flight were purposely introduced through the use of increased or decreased pitch inputs on the control column. The speed trim system was then observed to make trim inputs opposite of the speed deviations to encourage the aircraft to return to its originally trimmed airspeed. Once the originally trimmed airspeed was re-achieved, the speed trim inputs were automatically removed by the system.
The speed trim inputs were accomplished by the slow rate of the trim motor as the flaps were already up. The effect of these inputs was subtle and easily overridden if needed.
Approach to Stall/Stall Demonstration
After level off, we each were directed to pull the power to idle but to maintain altitude in manual flight through pitch control to observe the annunciations and flight control behavior during a stall. The approach to stall maneuver has been a staple of airline training for many years, but typically the maneuver would terminate with the activation of the stick shaker stall warning followed by a recovery. It was felt that exploring actual stall characteristics was unneeded and possibly negative training as this situation would never theoretically materialize in actual line operations. A recovery would always be made upon the activation of the stick shaker.
In the aftermath of the Colgan and some other crashes which served to highlight concern about deficiencies in manual flight skills, the FAA introduced extended envelope training (EET). This training went beyond traditional airline flight training to explore flight handling characteristics in areas of the flight envelope that would never be expected to be seen in line flying. The new thinking was that having some experience in these unusual situations might be of use in case one ever developed.
We were asked to make nose up trim inputs down to the lowest flaps up maneuver speed and afterward to continue to maintain altitude through control column pressure alone. A number of visual and aural alerts displayed and sounded as airspeed continued to decrease. The aural “Airspeed Low” alert sounded followed by the “Buffet Alert” FMC advisory message. The pitch limit indication appeared showing that we were within 5 degrees angle of attack to stick shaker activation. The stick shaker activated upon reaching the airspeed where natural stall warning buffet is computed to commence by the stall warning yaw damper (SWYD) computer.
During this demonstration, rearward control column forces continued to increase. As airspeed decreased below minimum maneuver speed, the speed trim High AOA mode activated thereby adding nose down trim at the slow rate of speed (because the flaps were retracted). This served to increase the necessary force to maintain altitude. Note that the high AOA speed trim feature is not unique to the MAX, but is included on older 737 models.
Eventually, the trim wheel made an abrupt twitch forward at the high rate, but only for a fraction of a turn. This, our instructor told us, was the MCAS system becoming active or “waking up”. What was happening behind the scene was the MCAS logic took a “snapshot” of the existing trim position when its threshold AOA was reached. It then calculated a maximum amount of trim that could be added. Should the trim ever meet this computed limit, the speed trim and MCAS system becomes inhibited for the remainder of the flight. A short time later, MCAS activated adding additional nose down trim at the high rate of trim motor speed. The control forces were now heavier, but still manageable.
Finally, the Elevator Feel Shift (EFS) module increased the system ‘A’ hydraulic pressure to the elevator feel and centering unit as the AOA approached its stall value. The elevator feel and centering unit is how any elevator force is transmitted to the pilots through the control column. Changes in trim go through this unit before they are felt by the pilot. This hydraulic pressure increase dramatically increases forward pressure on the controls and felt like someone was trying to jerk the controls out of my hands. Again, it should be noted that the EFS module is not unique to the MAX but is also included on earlier 737 models.
Full Stall
At this point the aircraft was in a full stall with strong buffet being felt. The controls could still be held aft, but only with two hands on the yoke and significant effort. We were then instructed to release back pressure and to let the aircraft recover and accelerate. The aircraft recovered quickly. The inputs previously made by MCAS and speed trim were automatically removed as airspeed increased and AOA decreased.
This was the end of the demonstration. Both of us ran through this event several times so that we were familiar with the sequence of alerts and flight control inputs. 737 stall behavior is benign with no significant roll or wing drop being noted. Recovery was prompt with back pressure release and flying airspeed was quickly reestablished.
All aircraft with a powered trim system are subject to a condition known as runaway trim. Recall that elevator trim repositions the horizontal stabilizer in order to “trim” the aircraft to a particular airspeed. When properly trimmed, elevator stick forces are minimized. “Trim to relieve stick pressure” was the mantra when I was in USAF pilot training in 1982. It is still true.
The converse that a badly untrimmed aircraft is difficult or impossible to fly is also true. An inoperative trim system is sub-optimal, but one that continues to trim after the trim switch is released, or trims on its own can quickly create a dangerous situation. Stick forces will quickly become so unmanageable that continued controlled flight is not possible. This may manifest as either nose down or nose up trim. Neither is good.
Fortunately, Boeing has always included a non-normal checklist (NNC) to address runaway trim. If correctly followed, this checklist will result in the runaway trim malfunction being corrected, or the electric trim system being deactivated. Recall that the electric system, including speed trim, autopilot trim, and MCAS, has always been able to be deactivated through the use of the stab trim cutout switches located on the center stand.
Our demonstration started with the instructor introducing a runaway nose down rapid rate trim malfunction. The most important step of any non-normal event in an aircraft is identifying the malfunction correctly and then applying the correct non-normal checklist. Many an accident has been the result of a wrong assessment of the problem or the application of the wrong checklist.
Recall that it is now normal for the trim wheel to spin un-commanded by the pilot in manual flight due to inputs by either the speed trim system or MCAS. Since the flaps were up and the aircraft was not in a stall situation, the fast rate trim activation immediately telegraphed a malfunction.This is how an MCAS malfunction might present along with some nuisance alerts. At this point, accomplishing the immediate action items (IAIs) of the Runaway Trim checklist on the Quick Reference Card (QRC) followed by the remaining steps listed in the Quick Reference Handbook (QRH) left us in a situation with the aircraft in manual flight with the electric trim disconnected by the stab trim cutout switches.
Immediate action items are steps on a non-normal checklist that must be performed from memory due to their urgent nature. The Runaway Trim checklist contains several of these steps which include disengaging the autopilot and autothrottles, controlling aircraft pitch and airspeed, and disconnecting the stab trim cutout switches if necessary. This checklist has remained largely unchanged over the many different models of the 737.
At this point, the aircraft had to be flown and trimmed manually using the trim wheel. There is a note in the checklist which emphasizes that reducing airspeed helps to relieve the air loads on the stabilizer which reduces the efforts needed to manually trim. Our malfunction was introduced at about 250 knots. Manual trim at this speed took some effort, but was easily achieved. Slowing to 210 kts allowed the flying pilot to easily fly and trim without assistance from the non-flying pilot.
Close crew coordination is of course required to split the duties of trimming and flying depending upon the situation. Flight in instrument conditions might require the flying pilot to direct the non-flying pilot to manipulate the trim. Instructive to me was the ease with which trim changes through the configuration process were able to be made. We were directed to go around on short final to see the trim changes needed for that maneuver. Using less than full power for the go-around made the maneuver very smooth and controllable.
Unreliable Airspeed Demonstration
One of the most disconcerting and dangerous malfunctions any pilot can face is the loss of reliable airspeed. Airspeed is the oxygen of controlled flight, and loss of reliable airspeed must be quickly recognized and corrected or ameliorated for a successful outcome. The importance of this instrument is why there is a lot of redundancy built in. The 737 has two primary and one auxiliary pitot probes used to measure dynamic air pressure which is then converted to airspeed measurement for the pilot’s primary airspeed indicators along with an auxiliary airspeed indicator.
In addition to the direct measurement of airspeed, the 737 has displays of groundspeed derived from the air data inertial reference unit (ADIRU). While airspeed and groundspeed are not the same, at low altitudes, they are close enough to be useful.
Our demonstration simulated a bird strike or similar damage on takeoff which disabled the captain’s alpha vane AOA transmitter though we were not informed of this beforehand. Immediately after rotation, a cacophony of alerts sounded accompanied by numerous messages on the displays. The indications included AOA Disagree, ALT Disagree, IAS Disagree, Speed Trim Fail, Feel Diff Press, along with erroneous airspeed, altitude, and flight director indications. The stick shaker sounded and did not cease for the entire demonstration.
As I mentioned above, the most important thing in any non-normal situation is to recognize what has failed and more importantly, what has not failed. A quick scan of the first officer’s and auxiliary airspeed indicators told us that it was my instruments that had failed as the other two instruments were in agreement. I transferred control of the aircraft to the first officer who continued the climbout as I then referenced the Unreliable Airspeed checklist.
This checklist is fairly straightforward directing the autopilot and autothrottles to be disengaged if engaged. The flight directors are not to be used as they may also give erroneous information, and lastly for complete airspeed failure, some known pitch and power settings are given which are calculated to keep the aircraft from stalling or overspeeding.
We explored setting these values to see the performance of the aircraft with flaps both retracted and extended. The checklist values will keep the aircraft safe until a more detailed chart in the quick reference handbook, which uses aircraft weight, altitude, and phase of flight to set pitch and power, can be referenced.
Since our situation resulted in useable airspeed indications for the first officer, returning the aircraft to the airport was a matter of accounting for the nuisance stick shaker and other alerts, accomplishing the appropriate checklists and landing. We had been advised to bring ear protection for this segment, and it was worthwhile advice.
Changes Made to the MAX
The changes made to the MAX center around added redundancy to the Speed Trim System (including MCAS), and the Flight Control Computer. Input is now used from both AOA vanes and compared before being routed to the MCAS system. Previously, MCAS received input from only one AOA vane. A difference between input values from the two sensors will inhibit the system. New logic has been added which limits the amount of trim that the MCAS system can add. An exceedance of this limit also inhibits the system.
Additional safeguards, redundancies and self monitors have been added to the flight control computers themselves to prevent erroneous stabilizer trim commands. The odds of a runaway trim scenario are now effectively nil, but the runaway trim procedures and checklists will remain as immediate action items on the quick reference cards and handbooks.
Conclusion
I published my impressions of flying the MAX back in 2018Thoughts on the Boeing 737-MAX 8 By A Captain Who Flies One after I first flew the aircraft. I thought it was a great flying machine back then and I think it will be better than ever after its return. Was the aircraft as well designed as it could have been? Perhaps not, but then in no human endeavor is perfection ever achieved. I do not mean to denigrate the seriousness of the accidents that occurred nor the memory of those lost. Airline crashes are nightmares for all involved.
That said, underlying causes of any accident are complex and many differing narratives develop, some with agendas of their own. Causal chains behind any accident must be considered in total. A focus upon one aspect of an accident in isolation will inevitably lead to a missed or wrong conclusion.
Having now flown both the old and newer versions of the MAX, I am more convinced than ever that this aircraft is rock solid, whatever discrepancies there were have been corrected, and that it has a bright future as the preeminent narrow body airliner.
Airliner technology continues to evolve year-after-year, in the pursuit of better fuel economy which leads to better financial yields for operators. There’s been a number of initiatives over the years from all aircraft manufacturers, but in the 1980s unducted fan (UDF) technology was showing promise for reducing fuel consumption substantially on new model aircraft for the 1990s.
McDonnell Douglas was one of the manufacturers that pursued this new technology for nearly a decade before abandoning it as a future airline powerplant.
Image: McDonnell Douglas
An Attempt To Push Beyond The Turbofan with UDF
Modern jetliners operate on turbofan engines, which quite simply have a ducted fan attached in front of a turbojet engine. Going into detail on turbofan construction and operation would require a separate article; but the turbine creates the bulk of the thrust, the ducted fan creates additional thrust and lowers the overall noise footprint of the engine, and this is what modern jetliners use to operate their aircraft.
In 1973 when OPEC engaged in an oil embargo with nations that were perceived to support Israel during the Yom Kippur War, oil prices shot up overnight resulting in an increase from .36 cents a gallon to .53 cents a gallon.
By 1974, a barrel of oil had quadrupled versus the previous years. The embargo ended six months later, but the price of oil and subsequently gas prices continued to climb. A gallon of gas reached an average of $1.19 a gallon just six years later, a substantial climb in price, nearly four times higher than 1973. But it didn’t stop in 1980, gas just continued to climb in price leading to a serious effort to find and update powerplants to be more fuel efficient.
An Opportunity To Improve Fuel Efficiency
NASA actually led the way to look for new technology and concepts to reduce fuel burn, by working with manufacturers and providing NASA funded research grants. Manufacturers looked at ways to make their aircraft more fuel efficient in light of the overnight fuel crisis which led to increased fuel prices.
Suddenly aircraft that burned massive amounts of fuel were a pain point for airlines. One of the key powerplants that showed promise was Unducted Fan (UDF) technology. Two key powerplant producers, Pratt & Whitney and General Electric invested in this technology with prototype engines, and Boeing and McDonnell Douglas provided aircraft test beds and perceived new aircraft models to present to airline customers.
Additionally, other manufacturers such as Fokker, British Aerospace, and Tupolev all invested in testing out alternative prop-based powerplants to varying degrees over the years.
UDF: The Unducted Fan Emerges As An Option
While little information is available, McDonnell Douglas was looking at UDF technology for the newly launched MD-80 series as an option. Interestingly enough, the early rendition in the form of a 1/100 scale model differs considerably from the powerplants that did eventually take flight, featuring forward facing prop fans.
It was a close rendition of the eight bladed Allison 501-M78 and a Hamilton Standard propeller, used in a NASA propfan test. These early units were modified turbofan engines with the fan placed outside the engine nacelle on the same axis as the compressor blades, and assumed this was an early design study from 1981.
“Props” for McDonnell Douglas: Unducted Fans (UDF) Never Took Off 54
NASA had released their internal studies on propfan technology to engine makers who were interested in pursuing the technology. By 1984 NASA had awarded a contract for $20m to further study and pursue the concept of an open rotor powerplant to General Electric (GE). GE was working closely with Boeing on the UDF as a possible new short haul aircraft powerplant, dubbed the 7J7 for a market introduction in 1991.
The 7J7 was a widebody short haul aircraft with a range of up to 2700 nautical miles initially. But Boeing ended up pitching a hybrid-narrowbody concept at 155 inches to airlines as the final configuration, with a 2-2-2 seating configuration ensuring there was no middle seat. That was depending on the airline customer you talked to, as it was said Boeing kept changing their minds as to what the aircraft was and would be.
UDFs Became All The Rage
Image: NASA
GE unveiled their engine concept at the 1984 Farnborough Air Show, promising up to 30% reduction in fuel burn without decreasing inflight cruise speeds. Two key points for GE’s proposal was twin contra-rotating fans which kept fan blade length to a reasonable size (12 feet) vs. a single prop at nearly 20 feet in diameter.
The second selling point was the lack of a gearbox, which transfers power from the turbine to the propeller. Beginning in 1986, the GE36 flew a considerable number of test flights, achieving a cruise speed of Mach .84 at an altitude of 39,000 feet on Boeing’s test 727 aircraft.
There was significant interest from British Airways as a replacement for its 737-200s, SAS, and American Airlines. However, British Airways selected the Boeing 737-300 instead. American Airlines had concern if the 7J7 could be stretched further using the same powerplant. Internally at Boeing, the 7J7 was viewed as a political football: a possible new line of fuel-efficient aircraft, or the grim reaper for the 737 line. In the end American Airlines went with the Fokker 100 aircraft based on availability.
The engine technology while progressing, wasn’t going fast enough to guarantee a launch of the 7J7 by 1991. With competition brewing from McDonnell Douglas not to mention the newly introduced Airbus A320, Boeing ended up postponing and subsequently canceling an UDF powered aircraft. But McDonnell Douglas pressed on.
Image: NASA
McDonnell Douglas Kept On Developing UDF Concept
Allison Engine Company which already had a head start on a similar concept, partnered with Pratt & Whitney in 1987 to produce a prototype UDF for a test run on an McDonnell Douglas airliner. While Allison had produced a smaller prototype and tested in conjunction with NASA back in 1981, it was playing catch up to the GE36 in 1985, which flew first.
Pratt & Whitney would not be able to develop and certify an original engine design to meet the aircraft launch dates, and thus partnered with Allison to speed up development. The engine was proposed in two sizes, with the smaller variant a 10k shaft horsepower and 23:1 compression ratio, with a three stage boost compressor and power turbine for 100 passenger aircraft; and a larger 15k shaft horsepower aircraft for up to 160 passengers.
The engine was dubbed the 578-DX, but unlike the GE36, the 578-DX would in fact have a reduction gearbox, and claim an additional 7% fuel savings as a result. But having a gearbox meant more maintenance and reliability headaches and airlines were wary. Allison claimed that the gearbox would need an overhaul after 30,000 hours, and was in fact reliable (although this would never be proven).
McDonnell Douglas Goes All In On UDFs
McDonnell Douglas was already planning its next range of airliners based on the successful MD-80 series. The first of these next generation airliners was the MD-90, an updated version of the MD-80 with all new engines and a glass cockpit, better range and less fuel consumption.
It would also address noise by having a lower noise profile than the current JT8D engines. But this was expected to be a stop-gap measure until UDF technology matured and eventually replaced jet powered MD-80 and 90 aircraft. Subsequently, McDonnell Douglas began marketing the MD-91 and MD-92 aircraft as early as 1985, all powered by UDF engines by GE or P&W.
The MD-91 was a copy of the MD-87 with UDF engines. Photo: McDonnell Douglas
Mutiple MD-9X Varients
The MD-91 would have been the smallest capacity of the offerings, at 114 passengers (2 class) or 130 passengers (all economy) and just under 129 feet in length. It would utilize the MD-87 fuselage, but with the wing shifted 3 feet further back. The MD-90 (traditionally powered) would carry 153 passengers (2-class), or up to 172 passengers in all economy configuration, with a fuselage length of 152 feet.
Finally, the MD-92 was slightly larger at 157 feet in length, utilizing the MD-88 fuselage (lengthened 133 inches forward of the wing), and 165 passengers (2 class) or 173 passengers in all economy. All aircraft would feature a composite horizontal stabilizer, with split powered elevator and rudders and a full glass digital cockpit. There were subsequent other aircraft marketed like the MD-94, but this was proposed to be a clean sheet design to compete with Boeing’s 7J7.
The Jet Is Too Dang Loud!
There was the perception an open rotor aircraft suggests interior noise to passengers. McDonnell Douglas claimed that the interior cabin noise levels of the MD-91/92 would be 80dB, which would make it up to 6dB quieter than the jet powered aircraft.
McDonnell Douglas claimed that the demonstrator registered 82dB during testing, and that airline executives who flew on marketing flights made statements like “very quiet, better than expected” or “airplane very quiet, particularly in the last row.”
This conflicted with reports of other members of the travel industry who said it was very noisy inside, a different type of prop sound, but certainly noticeable and generating some cabin vibration (that would be addressed later on). The marketing test flights were carried out of Long Beach, and flew airline personnel, media, military, and other industries (181 people carried total). The aircraft would fly out of LGB and out over the Pacific Ocean, directly over Catalina Island, then it would turn left and south where it would make a U-turn over San Clemente island and descend back to LGB.
“Props” for McDonnell Douglas: Unducted Fans (UDF) Never Took Off 55
McDonnell Douglas UDF: Ultra-Loud and Ultra Efficient
The GE36 was also tested on the McDonnell Douglas MD-80 testbed for a future MD-9x series of aircraft a year later in 1987. It was modified from an 8×8 blade set up (8 blades on each counter-rotating prop) to an 10×8 with the rear prop containing 8 blades versus the forward props 10 blades.
This configuration resulted in quieter operation, and that a commercial production version would have different blade counts on each prop to achieve the desired noise profile and best performance. Most of the test flights with the McDonnell Douglas MD-80 test bed were performed with the GE36, as the P&W option was way behind schedule.
Most testing on the MD-80 testbed was with the GE36, which achieved a maximum speed of Mach .865 at 37,000 feet. This powerplant would accomplish 165 hours over 93 flight tests, substantially more than the 578-DX.
McDonnell Douglas began to refer to the UDF with another acronym: UHB – Ultra High Bypass, and came up with further variations and aircraft types utilizing the UHB acronym. They were marketed with up to 40% less fuel burn, but ignoring the substantial cost increase to acquire these new powerplants. McDonnell Douglas was even discussing offering powerplant retrofits on existing MD-80 series aircraft.
McDonnell Douglas, Exclusive Purveyor of UDFs (On Paper)
Once Boeing cancelled the 7J7, McDonnell Douglas in marketing materials to airlines began saying you can’t get UDF technology from anyone but McDonnell Douglas. This was all based on the GE36, because up to this point the 578-DX had not flown on an McDonnell Douglas airframe having missed numerous milestones in the schedule due to a variety of issues.
McDonnell Douglas Offers a Military UDF
McDonnell Douglas was so confident in what the UDF offered that it entered a military variant when the Navy began a search for a new patrol aircraft, specifically the Long-Range Anti-Submarine Warfare Capable Aircraft (LRAACA) competition launched in January 1987.
This competition was seeking replacements for the ageing P-3 Orion aircraft. No other manufacturer other than Lockheed had interest in building a derivative to the P-3. But the Navy wasn’t going to just hand Lockheed a contract without bidding it out, and thus expanded the scope to include commercial aircraft derivatives in March of 1987.
McDonnell Douglas submitted an MD-91 derivative, ironic given the MD-91 hadn’t officially flown yet. The designation for the derivative was P-9D, and it was the UDF powered MD-91 but with additional equipment. McDonnell Douglas was offering either engine (P&W or GE) as a choice to the Navy, even though the 578-DX hadn’t flown on the MD-80 test bed.
The P-9D was presented as having a 45%+ lower fuel burn than the current P-3 Orion. The P-9D would have carried the latest electronics and sensors, along with AGM-84 Harpoon Missiles and operating with a crew of 11. Nonetheless, in October of 1988, the Navy selected the Lockheed proposal (P-7) which was significantly lower in cost than the McDonnell Douglas proposal, while also being judged technically superior with less technical risk.
Progress Continued
McDonnell Douglas soldiered on with the commercial MD-91 and MD-92, flying the UDF prototype to the Farnborough Airshow in 1988 equipped with the GE36 engine in hopes of drumming up sales.
The 578-DX would undergo ground testing from late 1987, with scheduled in-flight testing (installed on an MD-80 test bed) planned for early 1988. Due to repeated mechanical and engineering issues encountered on the ground, the 578-DX didn’t take to the air until April of 1989, nearly two years late. But when it did, it reportedly flew without issue at a speed of up to Mach .77 at an altitude of 30,000 feet.
McDonnell Douglas Even Toyed With a DC-10 UDF
McDonnell Douglas was even experimenting with the idea of replacing the turbofans on the DC-10 with UDF powerplants, with one example being given the conceptual designation “UHB-270”, but never appeared outside of model form.
After years of delay, McDonnell Douglas killed off the UDF variants of its new MD-9x airliners in May of 1989, one month after successful testing of the 578-DX. It was clear that the engine delays would further push the MD-9x series of aircraft further into the mid-late 1990s before airline customers could take delivery. And GE wasn’t interested in moving forward with their UDF unless McDonnell Douglas had firm orders for at least 150 aircraft.
Caught in chicken-and-egg scenario, airlines were generally reluctant to order a brand new type without the manufacturer fully committing to the type. But McDonnell Douglas wasn’t going to commit to anything, from guaranteeing performance data to manufacturing the aircraft without orders.
The End of the Road For The UDF
What killed the UDF concept? Price, price and price. The price of fuel when the UDF concept kicked off was at the top of the market, and climbing by the day. But when the UDF concepts finally flew, the price of gas had begun to drop. From a high of $1.31 a gallon in 1981, by 1986 gas was averaging .86 a gallon.
Gas was no longer perceived as a financial gating issue compared to the early 1980s. The second problem was the price of the powerplant. Pratt & Whitney’s 578-DX was forecast to be 40% higher in cost to purchase than a turbofan that was currently available for Boeing and McDonnell Douglas aircraft. The economics just didn’t quite work the way they expected. Finally, no airline customer put in a firm order for the prop-fan powered airliners. All three of these issues killed the UDF concept.
A proposed DC-10 derivative with UDF Engines. Photo: McDonnell Douglas
But all was not lost, and a lot was learned from the UDF exercise. The technology to build the UDF’s fan blades was used to develop the fan blades for the GE90, one of the engines that powers the Boeing 777 aircraft. The technology using composite materials is now used in many aircraft parts. And there are still companies, GE included, who continue to look at UDF technology.
Remember the good ole days at Los Angeles International Airport? It was filled with four engined domestic flights on widebodies like the Boeing 747-100 and L-1011.
Times have definitely changed at LAX. Today, it is dominated by the Boeing 737 and Airbus A320 series jet along with a host of 787 and 777 flying the international routes. While there are a number of 747 cargo flights, most passenger 747s are now a thing of the past. Even a A380 is becoming rare these days.
In the video, you’ll see a United Boeing 747-100 probably arriving from either Honolulu or Chicago O’hare along with an Eastern Airlines L-1011 preparing to depart to Atlanta. You’ll also see a host of Western Airlines 727s and a TWA 707 at the gate. This two minute video also features international 747 arrivals from Lufthansa and Air France. It’s worth a watch…and makes us pine for the days long gone where both variety, prestige, and size mattered more than efficiency.
The video was posted on YouTube by SDMullis. Check it out!
Most people will say that 2020 was a dumpster fire. The pandemic has caused untold misery with millions infected and over a million dead around the world. The aviation industry has been upended. Airlines have failed and many airlines have retired their fleets (most notably the near worldwide retirement of the A380 and 747 passenger fleets along with the retirement of all MD-90 and most MD-80 aircraft fleets).
Last year we profiled 5 of the weirdest emotional support
In a year where there is almost nothing to celebrate in the airline industry, there is finally a positive change that most of us can get behind. Alaska Airlines has banned emotional support animals with other airlines adding additional restrictions. If you’ve ever sat next to a growling dog on a flight or had the pleasure of sharing a bulkhead with a miniature horse, you’ll probably rejoice.
Airlines Are Now Adopting More Restrictive Rules On Emotional Support Animals
(Photo: Avgeekery)
Alaska Airlines announced a new policy that will ban any emotional support animal. They are the first major US airline to do so. According to their website:
“Effective January 11, 2021, Alaska will accept only service dogs which are trained to do work or perform tasks for the benefit of a qualified individual with a disability. Emotional support animals will no longer be accepted.”
New Rules For Emotional Service Animals Came After Complaints to the US DOT
Earlier this year, we reported that the US Department of Transportation proposed more restrictive rules on emotional support animals. These rules allowed “airlines to place additional limitations on ESAs and/or prohibit them all together on flights.
The airlines could place other restrictions on ESAs like requiring passengers to check in before most other passenger are required to show. Passengers with ESAs would also be required to show that the animal has a DOT Animal Air Transportation Health Form. Airlines can also place limits on the size and type of animal.”
Additional Restrictions Likely
Other airlines have implemented additional restrictions as well that include limiting the total number of ESAs on a flight and additional documentation requirements. While there are many valid purposes for service animals and even emotional support animals, the abuse of the previous rules have led to additional restrictions.
DELTA AIR LINES REQUIRES ADDITIONAL DOCUMENTATION
Beginning in March of this past year, Delta Air Lines added additional requirements for anyone who wants to travel with an ESA. According to Delta’s website:
“Delta requires that all customers traveling with a service or support animal show proof of health or vaccinations 48 hours in advance. In addition to the current requirement of a letter prepared and signed by a doctor or licensed mental health professional, those with psychiatric service animals and emotional support animals will also need to provide a signed document confirming that their animal can behave to prevent untrained, sometimes aggressive household pets from traveling without a kennel in the cabin. These measures are intended to help ensure that those customers traveling with a trained service or support animal will no longer be at risk of untrained pets attacking their working animal, as has previously been reported.
“The rise in serious incidents involving animals in flight leads us to believe that the lack of regulation in both health and training screening for these animals is creating unsafe conditions across U.S. air travel,” said John Laughter, Delta’s Senior Vice President — Corporate Safety, Security and Compliance. “As a leader in safety, we worked with our Advisory Board on Disability to find a solution that supports those customers with a legitimate need for these animals, while prioritizing a safe and consistent travel experience.”
Return to a more rational cabin where people with real needs are supported but end to abuse of policies?
The hope is that these more restrictive policies will return to a more rational system where individuals with true needs are still supported without unnecessary burden. At the same time, the new policies should discourage pet owners who were abusing the policy to travel with their pets.
Do you have an experience with an unruly emotional service animal? Let us know in the comments below.
