Watch Your Altitude! Measuring World Altitude Records

The number one record on the National Aeronautic Association’s ”Most Wanted” records is the absolute altitude in a powered airplane with an internal combustion engine. The current record is 56,046 feet and was set, incredibly, on October 28, 1938, by Mario Pezzi of Italy in a Caproni Ca 161. The record will be 75 years old this October. Wow! To break the record, one needs to achieve 57,728 feet. Any takers? There are a few airplanes around that could probably do it, with some modifications and a partial-pressure or pressure suit.

Speaking of altitude though, how do you know what that altitude really is? Altitude seems to be the one measurement we still have a hard time getting right after all these years. I was recently looking through some old “Aviation and Aeronautical Engineering” journals from the 1920s, and I ran across some articles about a controversy in how the altitude record in the 1920s had been set.

On February 20, 1920, after taking off from McCook Field in Dayton, Ohio, Major Rudolph Schroeder reached 36,118 feet of altitude in a Lepere biplane, according to a barograph he carried aboard. This new record surpassed the old record of 34,910 feet set by Roland Rolhlfs, a test pilot for the Curtiss Engineering Corporation, the previous September in a Curtiss tri-plane owned by the Navy.

The problem was, neither altitude was corrected for temperature. When the altitudes were corrected for temperature, the true altitude attained by Rolhlfs actually turned out to be 32,450 feet, and the true altitude attained by Schroeder was only 30,835 feet. What happened?

The altitude measured by a barograph is based only on the pressure of the atmosphere. As altitude goes up, the pressure goes down. However, the pressure only provides an estimate of the true altitude, which is a fixed quantity. The pressure altitude will vary significantly for a given true altitude, as temperature also affects the pressure that is measured. In general, given the same pressure for a colder temperature, the true altitude will be much lower than for a higher temperature.

It appears the FAI had all this sorted out by the time Mr. Pezzi set his record!

I started thinking about measuring altitude as a result of this and realized that even today with all our modern technology we still have issues. When pressure from a barograph (or altimeter) is corrected for temperature, there are still measurement errors in the barographs and the temperature instruments themselves. This is one of the reasons that aircraft flying at high altitudes fly at uncorrected pressure altitudes and are separated by at least 1,000 feet in altitude.

Radar altimeters are another way to measure absolute altitude, but they can also have measurement errors. In addition, a radar altimeter measures the distance between the ground and the altimeter, so unless someone has a good model of the earth they are flying over, it’s hard to use a radar altimeter to measure absolute altitude.

One might think that GPS would have solved this, but once again, GPS tends to have the greatest errors in altitude. I have seen this many times, where a GPS unit knows my horizontal coordinates to within a few feet, but is 200 feet off in altitude.

Maybe the next great invention will be to figure out once and for all how to measure altitude as precisely as we can measure time and 2-D position. Thoughts?

Reference: “Determination of Altitude Records,” Aviation and Aeronautical Engineering 8(5), 1920.

The First Aerobatic Competition (Almost)

Throughout the first decade of aviation, pilots continued to learn about aerobatics and crowds continued to be wowed by daredevil maneuvers. Will Rhodes Moorhouse allegedly did the first tail slide in the spring of 1912, but the maneuver was probably really a hammerhead turn. In both maneuvers, the airplane begins by flying up a vertical line until the airspeed is zero (or nearly zero). In a true tail slide, the airplane does just what the name sounds like — it starts sliding backwards. It’s a common maneuver in both airshows and advanced aerobatic competitions. However, the tail slide can be hard on the airplane (and the pilot!) as some airplanes pitch violently downward in the recovery. I’ve done tail slides in some airplanes where you hardly even notice it (like my one ride in the back seat of an F-15) and other airplanes where your eyeballs just about pop out.

The hammerhead turn, on the other hand, is a vertical turn at the top of the vertical line. The pilot kicks the rudder to pivot the airplane about a point while simultaneously adding aileron and pushing the nose of the plane forward to keep everything in a nice flat turn. This maneuver takes a little practice, but is easy enough that it is included in all but the lowest rung of aerobatic competition.

The first aerobatic competition ever was planned near present-day Orly Airport in France on June 8, 1913 — almost exactly 100 years ago. The competition was supposed to feature a French pilot, Roland Garros and a Swiss pilot, Edmond Audemars. The contest was modest by today’s standards and was scheduled to include events in speed, climbs, and “fantastic and dexterous flight.” Presumably the latter made up the aerobatic portion of the contest, which had a 10,000 franc prize.

As the day approached, the French Aero Club and some journalists became concerned about safety and they lobbied the contest sponsors to replace the aerobatics with a more pedestrian spot landing contest. Yawn.

I’ve seen French pilots fly aerobatics in modern times, and they certainly don’t have that attitude any more!

 

 

 

 

What’s It Like to Spin an Aircraft?

Continuing my discussion on aerobatics and, in particular, spins, I thought I’d talk about what it looks and feels like to spin an airplane. I’ve done hundreds of spins (maybe thousands now that I think about it) in about ten different airplanes, and I’ve always been amazed at how similar they are. Some spin a little faster than others and some require more precise control inputs to recover than others, but overall, the techniques to both enter and recover from spins are very much the same across “spinnable” airplanes.

To understand what it’s like to spin in an airplane, imagine that you are lying stomach-down on a spinning merry-go-round. Obviously, from only a foot up, all you’re going to see is dirt, but imagine that you are now 2,000 feet in the air looking down. The ground twirling by is what a spin looks like. Most aircraft spin at around three seconds per turn (although I admit it always seems faster than that when it’s happening). The spin is also a “one-g” maneuver, so, just like the merry-go-round ride, you won’t feel any crushing g forces.

What I’ve just described is a normal, upright spin, which is usually pretty benign in most airplanes. Some spins can get a lot wilder! In an inverted spin you still see the ground but you’re upside down, and that can be a lot more disorienting. I also should note that I have never gotten into an unintentional upright spin while practicing aerobatics, but I have gotten into an unintentional inverted spin on two occasions. For one, I was pushing too hard during a hammerhead turn when I was first learning the maneuver and for the other I had a student use too much rudder at the top of an Immelmann (a half loop followed by roll out to level flight).

I did many spins in an A-37 when I was a flight test engineer at Edwards AFB in the mid-1980s, and it spun a lot like my Decathlon. However, because it was a jet, there were some noticeable differences. For one thing, the engines had a tendency to quit when we did inverted spins. You haven’t lived until you’ve seen every warning light in the cockpit come on all at once while you’re upside down and out of control! But, no problem – just recover from the spin, head towards the base and restart the engines. I remembered this several years later when the engine on my Decathlon quit as I was trying to enter a spin with a student. We immediately headed towards the Alamogordo, New Mexico airport while I restarted the engine. The propeller had stopped windmilling because our airspeed was so low, so I had to do a full start. No problem with the restart, but we still decided it was a good time to land!

Unfortunately I can’t find a good picture of one of the A-37s we used to spin at Edwards. I know there is one at the museum there so I’ll try to remember to take a picture of it next time I am there!

First Spin Recovery by Lt Wilfred Parke in 1912

As I’ve been reviewing the history of aerobatics, I’ve realized that it’s hard to say definitively exactly when certain events took place, such as who did the first spin and so on. Unlike distance and speed records, which were usually well documented and often even received much publicity, the first decade or so of aerobatic maneuvers were largely unplanned and not well understood. There were no official names for various maneuvers and the precise terminology used to describe aircraft maneuvers had not yet been established. As a result, when pilots found themselves in an odd position in the air, they often had trouble describing what had happened when they landed, that is, if they survived the encounter. Hence, what pilots might call a “spin” might in fact have been a steep spiral or just a tight, steeply banked turn.

In the “Airplane Flying Handbook,” the FAA defines a spin as “an aggravated stall that results in what is termed ‘autorotation’ wherein the airplane follows a downward corkscrew path.” So what is a stall? According to the FAA, “[a] stall occurs when the smooth airflow over the airplane’s wing is disrupted and the lift degenerates rapidly.” Lift is what keeps the airplane in the air – it essentially overcomes the weight of the airplane. Lift generally increases as what’s known as the “angle-of-attack” increases, but if the angle-of-attack is too high, the lift will detach from the wing.

Before an airplane can spin, it has to stall, by definition. And once it stalls, it won’t spin unless there is something to start the autorotation, normally one wing being more stalled than the other.

Whew! This is a lot to think about when discussing a spin, and the above is only about 25% of all the things that are really going on in a spin. Some people have devoted their entire careers to learning more about spins, so I’m not going to do that in one post obviously!

Anyway, the point of all this is that it’s hard to say who was the first person to really get into a spin because pilots in the early 1900s didn’t have such terms as “autorotation” and “aggravated stall,” and most had only a tenuous grasp on the relationship between angle-of-attack, lift, and the performance of their aircraft. These early aviators had to figure all this out as they went along, and modern aviators owe the safety we enjoy today to their legacy.

It appears that the first description of a successful spin recovery was recorded by British pilot Lt Wilfred Parke on August 25, 1912 as part of some flight tests in an Avro G biplane over Salisbury Plain (near the modern-day Boscombe Down, the UK version of Edwards AFB). Fortunately, Lt Parke was one of the first pilots to document his test flights, another legacy that modern test pilots continue to this day.

Lt Parke described a “spiral nose dive” that was apparently a left spin. In accordance with the beliefs at the time regarding spins, he first tried to add full throttle, thinking it would raise the nose up. He then tried to move the elevator full back to try to raise the nose and full left rudder in the belief that the spin was due to an uncoordinated maneuver.

Anyone who has flown a spin knows that the above actions are all exactly the OPPOSITE of what you do to recover from a spin. Since none of these “correct” inputs worked for Lt Parker, he finally retarded the throttle to idle and let go of the controls. Imagine his astonishment when the airplane returned to normal flight in less than a second!

Thus, Lt Parke became the father of a time-honored spin recovery technique – let go! It won’t always work, but it can be a good starting point.

Sadly, Parke’s promising career as one of the first test pilots was cut short when he died in another aircraft mishap just a few months after his spin discovery. However, we owe a debt of gratitude to him for helping to tame one of the mysteries of flight.

This description of Lt Parke’s spin came from “Flight Fantastic: The Illustrated History of Aerobatics,” by Annette Carson, Haynes Publishing Group, England, 1986.

Aerobatic Season Begins

Since the aerobatic competition season is underway, I thought I’d start with a short discussion on the early history of aerobatics. But, before I do that, I first want to show off my new toy — a 2003 Super Decathlon aerobatic airplane! I bought it in a partnership a few weeks ago and flew it for the first time on Saturday. I’m looking forward to many hours of upside-down flying in it.

Photo of Super Decathlon

2003 Super Decathlon
(Eileen Bjorkman personal collection)

On to the discussion about aerobatics. The thing that makes airplanes different from most other vehicles is their ability to maneuver in the air in all three dimensions, plus rolling, pitching and yawing. That ability also makes them harder to control, but the benefits outweigh the downside!

True aerobatics didn’t take place for about a decade after the Wright Brothers’ first flight in 1903. In fact, it was nearly a year after that flight, on September 20, 1904, that the Wright Brothers achieved their first full 360 degree banked turn. Since a turn is considered a maneuver in aerobatic competition, once could say that this was the first recorded aerobatic maneuver.

In 1908 Louis Bleriot, father of the modern monoplane, developed the control system that would make aerobatic maneuvers a reality. He came up with the idea of having a control stick for both pitch and bank together, with a bar operated by feet that connected to the rudder. This rudimentary system formed the basis for all modern aircraft control.

In August 1909 at the Reims Air Meet, Eugene Lefebvre wowed  the crowds by flying figure-8′s in the sky. Some have dubbed this the first ever aerobatic exhibition.

The daredevilry soon heated up, and in 1910 Walter Brookins started doing spiral dives and steep turns, allegedly once doing a 90-degree banked turn for 360 degrees of turn in about five seconds. However, Lincoln Beachey was the pilot who really both wowed and terrified crowds. He would dive vertically from 5000 feet and then pull up at the last minute to avoid hitting the ground.

As the maneuvers became more daring, exhibition pilots began crashing and dying in droves. Distressed over what he had wrought, Beachey stopped flying for a year in late 1912.

Tune in next time to see what happened next!

Source: “Flight Fantastic: The Illustrated History of Aerobatics,” by Annette Carson, Haynes Publishing Group, England, 1986.

Some History of Homebuilt Aircraft

Homebuilt airplanes are the lifeblood of competitive aviation. Nearly all racing airplanes are homebuilt or heavily modified “stock” airplanes, and until recently, most competitive aerobatic airplanes were homebuilt as well. Record-setting airplanes have long been a mixture of both production and homebuilt aircraft.

Despite the freedoms that we have today in the US regarding homebuilt aircraft, it wasn’t always that way.

Although all early airplanes were technically homebuilt, by 1926 the US government decided it was time to begin regulating aviation. Congress passed the 1926 Federal Air Commerce Act primarily to improve the safety of airmail deliveries that began in 1925, but the act also provided sweeping powers to the Secretary of Commerce – making air traffic rules, licensing pilots, establishing airways and navigation facilities, and certifying airplanes.

The 1926 act initially had little impact, as not many people were yet actually building and flying airplanes. However, Lindbergh’s 1927 Atlantic crossing electrified the world, creating thousands of aviation enthusiasts in the United States. Airplane designers, manufacturers, and flight schools sprang up almost overnight, and magazines such as Modern Mechanics and Inventions and Popular Aviation (precursor to Flying) began running articles on how to build small airplanes.

Most of these small airplanes were made from wood or steel tubing and fabric, which meant anyone who lived on a farm or had a woodshop had the materials, expertise and tools to build one. And build they did. After the stock market crash in 1928, homebuilt aircraft also provided the only affordable way for many to fulfill their dreams of flying. Since the 1926 Act did not specifically ban homebuilts, by the early 1930s small airplanes were leaping into the air from fields and golf courses across the US, sometimes with dubious results. Crashes were common, and although fatalities were rare due to low speeds, state legislatures and law enforcement soon took note of the aviation wild west taking place in their backyards. Something had to be done.

Although the certification requirements in the 1926 Act were intended to apply only to airplanes in interstate commerce, states began passing laws that applied the requirements to all airplanes. By the late 1930s, homebuilding was effectively outlawed in the US, with the exception of one renegade state – Oregon. Leslie Long, a reclusive airplane designer and builder from Cornelius, Oregon led a relentless fight against the other 47 states to repeal laws, but he gave up in June 1941 as the US entry into World War II loomed. Even if Long had won, it wouldn’t have mattered much at the time – everyone building airplanes left to fight the war. Long died in January 1945 without seeing his dream fulfilled.

However, others took up the charge. There were exceptions in the state laws that allowed people to build airplanes for racing and air shows. In 1948, an aviation-obsessed World War II veteran named Paul Poberezny from Wisconsin, modified an airplane for air show demonstrations. He soon had the idea to put together a band of people to reignite the homebuilding community, but had to put his plans on hold when he left again to serve in Korea.

Back home again in 1953, Poberezny pulled together 31 people for a meeting of what would become the Experimental Aircraft Association, or EAA. The purpose of the EAA was to foster homebuilding and promote high workmanship, while working with the federal government to ensure safe practices. As state laws dissolved, the movement took off slowly and by 1960, there were few hundred airplanes in the US certified in the “experimental” category.

Sources:

George Hardie, Jr., “The Long Road Back … The Lightplane Association of America, Part III,” Sport Aviation, April 1986, pp 36-38.

George Hardie, Jr. and John C. Burton, “The Long Road Back … Founding the Experimental Aircraft Association,” Sport Aviation, July 1986, pp 57-59.

EAA, “Encouraging for EAA,” Experimenter, May 1957, pp 24, 26.

Bob Whittier, “Popular Flying in the U.S.A.,” Sport Aviation, February 1959, pp 21-22.

FAA, “Brief History”.

 

85th Anniversary: First Aviation Speed Record Greater Than 300 mph

Yesterday (March 30, 2103) was the 85th anniversary of the first aviation speed record greater than 300 mph! The 318.6 mph record was set by an Italian, Major Mario de Bernardi, in 1928.

Mario_De_Bernardi

Mario De Bernardi
Courtesy Wikipedia

De Bernardi was no stranger to records — he already held the world speed record for seaplanes. He had also flown an unofficial absolute speed record the previous fall. On October 22, 1927, he flew a Macchi M.52 racing seaplane in four passes over a 3-kilometer course at an average speed of 301 mph, but for unknown reasons, the public annoucement put the speed at 298 mph. Since they thought the speed was still below 300 mph, the Italians decided not to bother submitting the speed to FAI for certification.

Macchi_M.52

Mario de Bernardi’s Macchi M.52
Courtesy Wikimedia Commons

After another attempt in November, 1927 that fell just short of 300 mph but set a world absolute speed record, the Italians made major modifications to the M.52, shortening the wings from 29.5 feet to 25.8 feet. This significantly reduced the wing area and resulting drag, which allowed the airplane to fly faster. On March 30, 1928, de Bernardi flew the plane, now called the M.52R, in four passes over a straight 3-kilometer course. He covered the total 12-kilometer distance in just a little over 40 seconds, breaking both the 300 mph and 500 km/hour barrier at the same time.

You can read more about de Bernardi in an out-of-print book, Victory Over the Wind, by Don Berliner, available used at Amazon.

Lindbergh’s Record Flight Planning: Risk and Reward

Following up from two posts ago, I wanted to discuss some of the considerations that went into Charles Lindbergh’s famous solo crossing of the Atlantic. This information is from his book, “The Spirit of St. Louis.”

Lindbergh was not the frontrunner to win the prize for flying from New York to Paris (or vice versa). Many of the contenders were much older and more experienced. In addition, Lindbergh was the only one to attempt the trip solo in a single engine airplane. The others used much larger multi-engine aircraft with at least one other crew member. The reasoning at the time was that two engines were needed for safety and more than one crew member was needed to help with navigation and crew relief during the long flight.

Lindbergh, on the other hand, believed that engine reliability had increased to the point where he didn’t need two or more engines. The multi-engine paradigm was also a red herring, as Lindbergh knew that even if a multi-engine airplane lost an engine, the airplane would not likely be able to complete the crossing. Given the state of the art at the time, the remaining engine or engines would simply increase the odds that the crew might make some sort of landfall instead of splashing into the ocean.

Spirit_of_St_Louis_1927_Stamp

Courtesy Wikimedia Commons

Lindbergh thought the best approach to the first non-stop Atlantic crossing was to use a single-engine airplane optimized for range. He minimized the weight as much as possible to maximize the fuel carried, flying by himself and taking only rudimentary survival equipment.

For navigation, Lindbergh had only a compass and some pre-planned headings calculated from a great-circle route. The Spirit of St Louis was unstable and difficult to fly and Lindbergh figured the navigation tasks and keeping the airplane under control would keep him awake.

Lindbergh also needed the right weather conditions for the trip. Although he had some basic instruments that allowed him to fly “blind” for short periods, he needed good visual conditions throughout most of the route, and he preferred a tailwind. Weather forecasting, especially across the North Atlantic, was still in its infancy, so the weather was the biggest risk to the flight. To help minimize that risk, Lindbergh planned the trip during a full moon to maximize his outside visibility during the crossing.

Lindbergh had many challenges as he crossed the Atlantic, but his biggest problem was just simply staying awake. He fought fatigue for more than half route, nearly losing control of the airplane on several occasions. The fatigue also made navigation difficult, as he continuously wandered off his intended heading. With no idea what the winds were, he really didn’t have a good idea where he was for most of the trip. He was quite shocked when he hit the coast of Ireland within a few miles of his intended spot.

Lucky or good? Probably a little of both, but his experiences with navigation on the trip sparked his interest in improving air navigation. There is a great article in the most recent Air&Space/Smithsonian magazine about his interest in navigation.

Lindbergh knew how to balance risk and reward. He took some chances, but they were calculated risks. And, as he said in his book, “Every pilot knows the chances he takes at times; that’s part of aviation. Ours is not a nation built on too much caution.”

Women and Air Racing

Since it’s Women’s History Month, I’m planning to talk about women aviators who race, set records, and compete in aerobatics for the next few posts.

The first official women’s transcontinental air race, the Women’s Air Derby,  occurred in 1929 and many prominent women pilots participated, including Amelia Earhart and Pancho Barnes. The race began in Santa Monica, California, and finished in Cleveland, Ohio. Louise Thaden won the race after flying for nine days (with many stops, obviously).

AR_Thaden_Louise

Louise Thaden
Courtesy Wikimedia Commons

You can read more about that first race at the website of the 99′s, the International Organization of Women Pilots.

Another pilot who started the 1929 air race was Mary Haizlip, who was married to racing pilot Jim Haizlip. Jim Haizlip had been a World War I pilot, and he met Mary when she came to his flight school to learn how to fly after the war. They married only 14 days after they met.

Mary Haizlip flew her first closed-circuit race in 1930, and Jim taught her much of what she needed by using a bedpost as a simulated pylon. In 1932, Mary set a women’s world speed record flying in an airplane she had flown for the first time only fifteen minutes earlier! That speed record stood for seven years, and she held two altitude records at one time as well. The airplane she used to set the record is show in the picture below.

Haizlip92

Mary Haizlip’s Record Setting Airplane. By Frank2040 (Template:Byron G. Como) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons

Despite the danger, Mary Haizlip was only involved in one serious accident. While testing an experimental airplane, the tail disintegrated and she broke her back in the subsequent crash. However, only two months later, she was flying again.

After World War II, the Haizlips moved to Los Angeles and Mary became a realtor because, as she pointed out, at the time there was no demand for eldery women test pilots.

The out-of-print book September Champions, by Robert Hull is available at amazon.com, and has an entire chapter about Mary and Jim Haizlip.

Why Set Aviation Records?

The topic of why someone would want to set an aviation record in the first place is a topic that I’m planning to discuss on occasion.

Athletes like to set records, but it seems that most of the time, the record set is incidental to winning the game, match, race, World Series, etc.

In the early days of aviation, record setting often was associated with winning. For example, prizes were offered for the first to cross the English Channel, the first to cross the Atlantic non-stop. In many cases, multiple aviators vied for these awards and these competitions became front-page news at times.

However, despite the obvious financial gains associated with winning these prizes, many of the competitors were after more than the money.

I recently finished reading “The Spirit of St. Louis,” Charles Lindbergh’s Pulitzer Prize-winning memoir of his Atlantic crossing, and I discovered that his main motivation for the flight was to show the world what airplanes could do. Lindbergh was a true aviation visionary, and he thought if he could fly nonstop from New York to Paris, he could convince the world that airplanes could do anything.

The fact that money was involved was a secondary goal for Lindbergh and in fact, after covering expenses and splitting the proceeds with his partners, I doubt if he gained much financially from the actual prize (although he certainly gained financially overall). When he took off, Lindbergh was also not even certain that he was even eligible for the prize, because the required time between his application to compete and his takeoff had not yet occurred. However, the weather was good enough, the moon was full, and the plane was ready, so he decided to go, despite not having slept much the night before.

On Friday, I’ll talk a little more about what I learned about Lindbergh’s overall Atlantic-crossing strategy from reading his book. By the way, the book has been in print since it was first released in the early 1950s, quite an accomplishment for an aviation book. If you haven’t read it yet, I highly recommend it!