Press: Model Aviation

Airplanes of The Aviator H-1 Racer

July 2005 Volume 31 Number 7

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As filming began on Martin Scorsese’s Academy Award winning movie, The Aviator, he was faced with a dilemma: how to accurately portray Howard Hughes’ aircraft and the film’s flying scenes in the film without having the original airplanes. Of those needed for the major flying sequences, one was no longer in existence and the other 2 were on permanent display in a museum, unable to fly.

Digitally re-creating flying airplanes is notoriously expensive and time-consuming, and the airplanes look unrealistic even after all the computer finishing work and digital special effects; they never convince the viewer that they are “real”. The Aviator’s executive producer, Chris Brigham was frustrated at having to “settle” for the costly, unconvincing digital effects, so he decided to try something that had never been done: create the largest scale flying models ever built.

Howard Hughes’ aircraft would need to be reproduced and flown realistically enough to convince movie critics and viewers that the flying sequences were authentic. That may seem simple, but these airplanes needed to be so big (with wingspans up to 30 feet), that they would be placed in the Federal Aviation Administration experimental aircraft category.

The technical challenge fell to Unmanned Air Vehicle (UAV) pioneer Joseph Bok, whose company, the Aero Telemetry Corporation specializes in building and flying UAV’s for the United States military. His designs and technical innovations have been used on many of the unmanned airplanes that are currently in service around the world.

He said:

“To pull off the effect of realism, the airplanes had to be big enough and heavy enough to fly as convincingly as a full scale airplane. Building three scale, unmanned flying models of this size, and flying all three of them within this time frame (roughly 12 weeks) has never before been attempted by anyone within a military or commercial aerospace entity…ever. Only the recent advances in technology implemented by skilled and experienced engineers could have pulled this off,”

Working at their Southern California facility, Bok’s team of 35 aerospace engineers and technicians put all their know-how and physical might into constructing several huge flyable models and 7 additional motion control miniatures. They did so relying only on old drawings and pictures from museum archives.

Aero Telemetry’s senior engineer and crew chief Darrel Hofmann said: “The XF-11 photographic reconnaissance airplane, the H-4 Hercules (Spruce Goose) or Hughes Flying Boat, and the H1 Racer were all built by the Hughes Aircraft Company in the 1930’s and 1940’s when aviation was still in its infancy. Hughes was a real aviation pioneer. He hired the best engineers in the world and spoke directly with the leading aviation experts of the time. He personally had a say in the design of the planes and he most certainly took on the tremendous personal responsibility of flying several them for the first time as the test pilot,” continued Hofmann, “This attests to the man’s skill in the cockpit.”

Joe noted: “Howard Hughes himself had an extremely difficult time with the real airplanes and was nearly killed in two of them while flying. Although historians have been unkind to some of his airplane designs (the XF-11 and Spruce Goose are prominently featured in a comprehensive aerospace reference titled The Worlds Worst Airplanes) I have become quite fond of both the XF-11 and H-4. Having studied them this closely I have come to see the subtle genius in each of the airplane’s designs. However, it was those particular design constraints that significantly impact any attempt to successfully build and fly a large-scale replica of them,”

“This meant I had to come up with a design that could fly very stable and provide a degree of safety with respect to low landing speeds and control ability.”

Joe as chief aerodynamicist and Hofmann as senior engineer, set to work perfecting an airfoil design that would do the trick. “For safety’s sake, Joe and I chose an airfoil with a significant tolerance for heavy airframe weight and minimized the onset of any tendency to tip stall,” said Darrel, “The airplanes had to built so quickly that they would have to forego the benefit of many standard weight-saving manufacturing techniques that would have otherwise been applied and therefore we knew we would have a reasonably high wing-loading going in.”

“We concentrated on High Reynolds number airfoils that tend to have lower airspeed envelopes but tremendous Coefficients of Lift,” added Joe.

Behind the scenes, Chris Brigham was busy negotiating with Jim Wright of Cottage Grove, Oregon for the use of his newly built, $2M full scale H1-B Racer. Jim had painstakingly replicated the aircraft and had just finished preparations for attending EAA Airventure - the premier aviation event at Oshkosh, Wisconsin. He would be slated to fly his airplane for the movie cameras once he returned in September.

As the Aero Telemetry design team members were settling in on their respective responsibilities on the XF-11 and H-4 Hercules, tragedy struck. On August 4th, 2003, Jim Wright was killed while flying his H1 Racer back from the Oshkosh event.

Stranger still, the propeller governor problem that had caused Howard Hughes to make an emergency landing back at Mines Field (Los Angeles International Airport) almost 75 years earlier, seemed to also have been a problem and may have contributed to this airplane’s demise. His death and subsequent loss of a fine aviator and airplane cast a long shadow on The Aviator cast and crew but also Joe’s team as well.

During the weeks that followed, a meeting was held at The Aviator and it was decided to call on Joe and his team to see if they could pull-off a miracle and come up with a ½ scale Hughes H1-B airplane in less than 10 weeks! Joe still had to build and fly the XF-11 and H-4 by the last week of October, all less than 8 weeks away!

After a lengthy conversation, Joe agreed to the challenge; he felt that with the addition of veteran aerospace machinist John Keefe and highly touted hydraulics engineer Butch Fleck, his group could handle the heavy load. The Aero Telemetry design and manufacturing teams were now split into two groups which had multiple responsibilities and two more complete shifts of laborers. “Because of the additional film scheduling issues, The Aviator required that the H-1 be the first airplane to fly even though it was the last plane ordered,” said Joe.

His airplane shop needed to run from 6am until midnight, seven days a week to get the job done. “The engineering design room was moved closer to the CNC machines so we could keep closer track of the parts and tolerances as they came off the line,” says Darrel.

John Keefe kept the CNC milling machines and lathes running at maximum output to keep up with all the custom built aluminum parts required for all of the airplanes. Joe’s engineering design team began to close the gap between untested computer drawings of parts and functional working aerospace machinery on the XF-11 and H-1.

“It was an amazing process to be a part of,” said Joe, “We would come with an idea on the back of a napkin and have it designed, built, and integrated within days of its conception…it was simply amazing”.

The initial plan called for a radio-controlled model that was half the scale of the original H-1. It had to take-off under its own power and fly at distances of up to three miles while performing numerous flight maneuvers.

It would require custom hydraulic retractable main landing gear (these had to be designed from scratch, built, tested and fully operational in eight weeks). Because of the model’s sheer size, the weight of the hydraulic and electrical systems, and budget and schedule constraints (which have an impact building options) it was anticipated that the airplane could weigh more than 400 pounds.

Heavy use of composite technology borrowed from years of working with the US military on classified projects would help the team build the airplanes quickly yet still provide a high degree of strength in the structure. Within four weeks the H-1 was beginning to look like a formidable machine

Aero Telemetry designed major H-1 Racer structures such as the retractable landing gear.

Ian Stevenson checks fuselage straightness. Airframe accurracy was of prime importance.

Howard Hughes in the cockpit of his world record setting H-1B Racer

The H-1B designed and built from old Hughes drawings begins to take shape

The H-1 wings over the cameras during a full plower low flyby.

Joe gives his H-1 one last bit of help as it taxis out to make its mark on history.

Construction and Design:

Many daunting design issues had to be addressed for all three airplanes. Each would be radically different from the others and would all have different engines and complex control systems.

Because of the compressed schedule it was decided to make the Racers’ fuselage from foam blocks designed in Solid Works™. It would be finish sanded by Aero Telemetry’s talented sculptors led by Jon Neill and Ian Stevenson. The finished fuselage would then be covered in fiberglass and painstakingly finished with strips of aluminum tape to give it the “flush rivet metal” look.

The wing was constructed using conventional wing building techniques, with the exception of including the new Aero Telemetry 28VDC hydraulically-actuated, fully retractable landing gear system for medium endurance tactical UAV’s.

Darrel said: “Fundamentally, in order for an airplane to fly, it must be balanced precisely at its Center of Gravity or CG. This was the single most difficult task for the H-1 Racer design and necessarily became the most critical issue.”

“The ultra long tail moment about the CG and Center of Pressure on the bottom of the wing coupled with the huge chord of the H-1 made the plane severely out of balance (aft CG condition) right on the drawing board. The hard part was that we had to make it look exactly scale.”

To solve the problem quickly, Joe and his crew had to design a complex yet coordinated wing and fuselage design that would place the maximum amount of weight and components in the forward section of the airplane, which was already cramped.

“Also, due to the thin airfoil thickness at the main spar and wing root where the landing gear attach points needed to be, extra consideration had to be given to the length of the landing gear, hydraulic system location and ground clearance issues due to the large diameter propeller,” remarked Joe, a former linebacker, who has a Bachelors Degree in Aerospace Engineering and a Masters Degree in Engineering Management from the University of Southern California. While there he studied under the auspices of renowned aerodynamicist Professor R.F. Blackwelder and Professor Robert H. Liebeck.

“This project required a substantial amount of aerospace engineering and a very practical application of mathematics, especially during the design phase of all three airplanes,” according to Joe.

While the H-1 was being finished and prepared for its all important film debut, work on the ultra complex XF-11 was progressing at a blistering pace. Critical engine and propeller testing for both models commenced at approximately the same time.

Aero Telemetry’s engine instrumentation engineer Kenny Schaefer said: “For about three weeks, all throughout the day we were blasted from our daily routine by the powerful engine test runs in the testing area next to the shop. They had the high compression engines running as good as could be expected and then they were modified further by us and tuned for maximum output by Joe (Bok) and John (Keefe)”. The group tried different types of fuel and varying ratios of fuel and oil until the right combination provided the required horsepower at a safe cylinder head temperature. Integration of the Aero Telemetry AT-DRV-3000 Telemetry and Data Acquisition System would later substantiate the preliminary ground test data with actual airborne test data.

By October 25th - the week originally scheduled for filming the H1-B racer, the fires in LA had decimated The Aviator set rendering it unusable. The accompanying heavy smoke made it almost impossible to breathe, much less film, so all outside shots were postponed for two weeks. This break in the action gave Joe and his team the respite they needed to continue.

They performed static load testing and CG tests, and the final finishing touches were added to the H-1’s cowl and fuselage. The engine, hydraulics, linear servo controls, Aero’s onboard telemetry system, and fuel supply system were retested and secured for flight. By this time the entire crew had been working two and a half shifts since September 16th and they were exhausted. “And we hadn’t even started the flight-testing portion of the project yet,” exclaimed Joe.

November 4th, 2003 - H-1 Racer 1st Flight Test, El Mirage Dry Lake Bed, California

November 4th, 2003 - the day for the H-1’s first flight – had arrived. The team was nervous and Joe was concerned that they had not been able to flight-test the airplane first. All other things considered, safety was the foremost issue.

When the crew arrived at Santa Clarita’s famous “Mystery Mesa” (A location just North of Los Angeles, long favored by Hollywood as a unique setting for films) they found a full movie set with more than 500 people milling about. Service trucks and vehicles were everywhere, only a crowned dirt road for a take off area. Above it all, the set was directly on a windy mountain top surrounded by extremely treacherous terrain, with no place to land in the case of an in-flight emergency.

“The area was completely untenable for aircraft to say the least,” Joe remarked, “Any problem with a critical component on an airplane this big and fast that might cause loss of control would spell certain disaster for the airplane and probably death or serious injury to anyone if it came into the crowded film set area.”

Besides the safety and liability issues for Joe, crashing the model was not an option at this critical point in the project. If the H-1 were to be destroyed while testing, there would neither be enough time nor resources to build another one to fit into the filming schedule and its flying scenes would be deleted from the script.

A crash at this early stage of the project would have resulted in the cancellation of the entire project, including the XF-11 and H-4 Hercules, which were already under construction.

The visual effects producer indicated that if Joe failed, the other models would be too risky, expensive, and dangerous to try. So this single flight would have serious consequences for the team; everything they had worked on up to this point was at extreme risk.

The combination of all these issues created such liability, pressure and anxiety within the team that Joe declined to fly at that location and time. It was decided that a proper flight test in a safe place was needed. The entire flight crew set off for a location roughly two hours away known as the El Mirage Dry Lake, which is located closer to Edwards Air Force Base and is in the high desert area of California. The lake bed is known as one of the flattest places on earth. Perfect for airplane testing.

The crew arrived tired from their early morning at Mystery Mesa but was relieved to be in a safe, remote area. After assembling the H-1, the team started final preparations for the flight. The hydraulic landing gears needed some final adjustments, as did the big military drone engine; the altitude was roughly 2700 feet above sea level and increased altitude decreases engine performance.

To help with the loss of power, it was decided to remove the mufflers from the engine so as to get every last bit of power it had. Although this increased power, it made working around the running engine almost unbearable; the exhaust noise sounded more like a 20mm machine gun than it did an engine!

In an eerie coincidence, the in-flight adjustable propeller pitch mechanism was not going to cooperate. This was the same type of problem encountered by both Howard Hughes (forcing an emergency landing at Mines field) and Jim Wright (ultimately causing his crash) A temporary fix was installed and the crew proceeded with a fixed pitch propeller. “We would try to keep the airplane climbing as fast as possible without over-revving the engine,” says John Keefe. “When the airplane got to a cruising altitude, the pilot could reduce power and try to see if the airplane would stay in level flight so we could get some real aerodynamic data from our H-1.”

With the major telemetry checks all showing green the only other problem was that the sun was setting fast in the west. With only minutes of good flying conditions left, Joe gave the launch signal and the arming switches were turned on the engine, a multitude of airborne electronic systems, and on the Aero Telemetry UHF uplink transmitter.

Seasoned RC pilot Jason Somes, pushed the throttle forward and with a final push from Joe Bok, the world's largest flyable model of the Hughes H1 Racer headed off for its date with destiny. It picked up speed after what seemed like forever, with the engine now running at full throttle, lifted it's tail and it started skyward. Cheers from the crew overpowered the sound of the engine.

Jason climbed the H-1 in relatively flat left hand turn that brought it back around toward the crew so they could get a visual on the landing gear and control surfaces.

Everything looked good, so he throttled back and the airplane settled in a little, moving in an oval racetrack pattern probably within roughly a mile of the ground control. Trim adjustments were made to the elevator for pitch stability, and it was time to retract the hydraulic landing gear. The switch was flipped and the gear disappeared into their wheel wells perfectly.

The H-1 flew better with the gear up, but the Jason was beginning to notice a considerable pitch stability issue. Whenever he slowed the model down with the engine throttle, it tried to pitch up. This is a deadly condition when combined with the over running propeller problem. Joe called for more altitude and the H-1 responded with a smooth climb-out before making another pass in front of the crew. It was time to come home.

Jason lowered the landing gear on the downwind leg; as the airplane made its base turn to final approach, those present stood still and held their breath for the set-up to landing. Jason leveled the wings for the final time and held the model in a nose level attitude while reducing the engine’s power to the point of nearly shutting it off.

The H1 descended quickly with the big three blade propeller wind-milling out in front and it became deathly quiet in the desert; no one spoke as all eyes were glued to the aluminum fuselage as it flashed in front of the crew and the model began to settle in a condition known as "ground effect." This is a buffeting that occurs as a planes wing nears the ground preventing it from touching the earth while riding on a pillow of air.

As the aircraft’s nose pitched up just a few feet off the ground, a tremendous roar went up from those present. It touched down in a perfect three point landing, skidding slightly to the right while sending up a rooster tail of dirt and sand from the fixed tail-skid assembly, signifying that the H1 Racer had made its way into aviation history and would live to fly again.

With pride in his voice, Joe said: “The pressure of the flight, its schedule and long hours of engineering manifested themselves in some tears of joy from many of those who had just witnessed the amazing flight of the largest unmanned Hughes H1 Racer in the world,” “The flight was significant in so far as it proved many of the design innovations that we (Aero Telemetry) brought to the project that were untested up till this point by anyone in the military or commercial aerospace with respect to Unmanned Air Vehicle design and manufacture. This flight would also provide the technical basis for the innovative Aero Telemetry command and control systems to be used on the remaining two airplanes.”

Many other issues had to be addressed before the H-1 would fly again for the film crews the following week. However, for all that had transpired to make this magnificent airplane come to life, this day had been one of the most amazing days in scale model aviation.

November 17th, 2003 - Film Flight at Santa Clarita, California

At Santa Clarita on November 17, 2003, the H1 Racer would now be flown and filmed to simulate the World Speed Record attempt that Howard Hughes had made in 1935 at Santa Ana, California.

Between the model’s last flight at El Mirage and the morning of the 17th, amazing things had taken place. At Aero Telemetry, a review of video and data telemetry from the test flight showed that several changes would be needed before the H-1 would fly again. Those modifications had to be made quickly and could not disturb the aircraft’s paint or delicate aluminum finish.

Meanwhile, the fires in and around Los Angeles had finally come under control and it had actually started to rain. With the principal filming finished at Mystery Mesa, the producers bulldozed and rolled flat a perfect runway. In addition, there would be a minimal number of people in the area so as to minimize safety hazard during the flight.

The Aero Telemetry crew arrived in the dark at 4:30am, and by 7am the engine was started and re-tuned for the locations altitude. After a lengthy safety meeting, the cast and crew prepared for an attempt. Two Fire trucks, an ambulance, and emergency personnel stood at the ready.

Joe explained: “We installed a new 48-inch diameter, three blade, in-flight adjustable propeller and was prepared to adjust it for the maximum pitch of around 54 inches when we got ready to cut the engine loose. The larger propeller required that the pilot take-off and land the Hughes Racer in the three point position or risk the chance of hitting the prop blades on the runway. Therefore the high angle-of-attack made the take-offs and landings very nerve racking.”

With Jason Somes back at the controls, Joe gave the order for the take-off run; the military engine roared to life as the H-1 rolled out on its first flight of the day. The take-off was not without its issues: the model got “a little sideways” from the engine torque and huge three-bladed propeller turning at a full 54 inches of pitch.

Although the runway was perfect, the airplane was so large that it was the width of the runway wingtip to wingtip. For the film effect, several old cars, trucks, and vintage airfield equipment lined both sides of the runway, making it a challenge to not hit anything with the model on take-off or landing.

The H-1 climbed out steadily, much to the amazement of the film crew and emergency personnel, who had never witnessed such a spectacle. When the airplane began its first pass over the film set in a diving left hand turn, the roughly 200 spectators were gripped by fascination. As the gear retracted and the airplane picked up speed, it seemed to transform into Howard Hughes flying the plane as he had more than 75 years ago.

At nearly the time Jason was getting more comfortable with the airplane’s handling characteristics, it came time to land and re-fuel. He shot a perfect approach to the top of the mountain and three pointed the aircraft right on the money. The several hundred film personnel and spectators cheered wildly as it settled in and slowed to a stop, using every inch of the bumpy runway.

Before the cheering had stopped, the Aero Telemetry ground crew was in action downfield, trying their best to ensure the H-1’s quick recovery and turnaround. But it was discovered that the rough runway coupled with the heavy down-force on the empennage had destroyed the fixed tail-wheel on landing.

Crew chief Hoffman immediately set about fabricating a fully functional replacement tail-skid assembly that not only worked perfectly for maintaining directional stability for the big Racer, but remained out of sight for the movie cameras during the next flight. “There wasn’t a machine shop available out there so it became a race with time for me to come up with a tail skid assembly that would be functional and strong enough to withstand the weight of the airplane and I only had about 20 minutes to do it!” he exclaimed.

While the movie crew busily reloaded ground cameras and made final adjustments to the aerial coordinator’s helicopter film cameras for the next flight, John Keefe and Roger Thornton quickly refueled the H-1 and Joe adjusted the engine for maximum power.

He said: “1/4 turn of the high speed needle put the big drone engine at a full military power setting. For the film sequences of Howard Hughes’ world speed record attempt, we not only tried to recreate something very special for Martin Scorsese and Chris Brigham, but also we were attempting to own the world speed record for the fastest ½ scale airplane manned or unmanned and I think we did it on this flight! We were clocked going downhill at somewhere around the 125 mph and it was an utterly amazing sight to behold.”

The next flight had an escort in the sky, a manned helicopter used for aerial filming. The H-1’s three point take-off was perfect and the landing gear were retracted before the airplane had even turned crosswind as it climbed out in a beautiful arc across the sky.

As the aircraft was brought out of the diving turn, the throttle was pushed full forward and the giant propeller turned at maximum pitch. The model’s incredible sound echoed throughout the canyons surrounding the set. Roger Thornton commented: “The H-1 made an incredible sound that literally echoed throughout the canyons surrounding the set. When they brought the airplane in at full throttle through the pylons only 20 feet from the ground, it sounded like a freight train and was indistinguishable from the real thing…it just literally shook the ground around us as it flew past.”

The aircraft’s rock-steady flight characteristics, high-speed, and detailed finish combined with the vintage airfield setting at the Mesa was completely realistic and convincing, even for the spectators. The Aviator Executive Producer, Chris Brigham who had witnessed the flight from the vantage of the helicopter, told Joe that “the airplane was simply breathtaking to watch from up there.”

After several passes through the mock speed course the H-1 was ready to land. Before it did though, Joe told Jason to perform an unscripted maneuver as a fitting salute to Howard Hughes and those who were there that day as witnesses to the Racers record setting flight.

As the model flew past the crew at full throttle “the H-1 did the most beautiful slow roll you’ve ever seen,” said Joe. “Probably something that Howard would have done too. The record setting performance of our H-1 Racer was absolutely breathtaking to witness and it was done under some the most extreme circumstances imaginable.”

Of the day, he said: “The incredible effort of my team during these last few weeks cannot be overstated. The airplane flew perfectly and provided the cameras with some of the most amazing aerial footage of the H-1 Racer that could have only been had if Howard Hughes himself was here to do it…in some ways I really think he may have been…”

Next month learn how Joe and the Aero Telemetry team designed, built and flew the worlds largest and fastest Hughes XF-11 scale R/C model for Martin Scorsese and The Aviator.