The Fabulous Supersportster Model's "R-1" and "R-2"

Brief history of the Gee Bee Supersportsters.

  • The Gee Bee "R-1" and "R-2" models were designed and built specifically for the 1932 Races. Bob Hall had left to form his own company. The Granville Brothers Aircraft hired Howell W. "Pete" Miller in May of 1932 as Assistant Chief Engineer. He had earned a degree as an Aeronautical Engineer from New York University in 1926 and had worked for both the Keystone Aircraft Co. and the Fairchild Airplane and Engine Corp. Engineers Don DeLackner and Allen Morse were also added to the engineering staff.

    The new racers would be called the R series Super Sportsters and were to be the fastest land planes in the world.

    Granville and Miller had no choice but to push as far out on the leading edge of technology as the modest resources of the Springfield Air Racing Association (SARA)and their little company would allow. Both ships were to be designed, built and test flown within the six months that remained before the 1932 National Air Races in Cleveland on September 1.

    They were, for all practical purposes, forced to use the wire braced, wood, tube and fabric construction of earlier Gee Bees, So from the start they accepted the fact to simply live with those materials and seek an edge elsewhere.

    They were also wedded to P&W air-cooled radial engines, so a blunt nose was another given that they would have to work around. It was a widely known engineering fact that the ideal shape for a body moving through a fluid was teardrop with a ratio between length and diameter of 3 to 3.5 to one, so Granville and Miller did a study to determine how close they could come to the ideal teardrop that had an engine, wings, landing gear, cockpit and a tail attached to spoil the airflow around it.

    1/10 scale mahogany models of the R1 and R2 Supersportser designs were tested in the New York University wind tunnel by Pete Miller, Granny Granville, and the famous aeronautical engineering professor Alexander Klemin to determine the wing positioning and stability coefficients.

    Demonstrating the scientific nature of their research, the Granvilles constructed 1/10 scale mahogany models of the R1 and R2 Supersportser and they were subjected to tests in the New York University wind tunnel. A year later, on May 18, 1933, Granny and his chief engineer, Howell W. Miller, presented a paper to the Society of Automotive Engineers in New York City describing the design and construction of their now-famous racers. Obviously they felt that they had two sound, viable contenders for the prizes offered in the upcoming races.

    Wing location was very important, and tests were made of mid-wing and low-wing configurations, plus a position about half way between the two.

    This three quarter position was found to create the least amount of drag, so it was selected.

    Tests were also run on various engine cowling shapes, wing filet sizes and gear leg fairings. Probably the test that had the most impact on the design was the stability tests.

    Engineers and pilots have notably always differed in opinion on the amount of stability fast airplanes should have. Engineers favor a lot of stability, maintaining that the less that a pilot has to control the airplane, the less drag will be created by the control surface and trim system displacement. Pilots on the other hand want a highly responsive airplane, even if that means cutting stability margins to the minimum. Granville and Miller decided to side with the pilots, knowing that a very sensitive airplane would result. They expected to gain performance by cutting down things such as tail volume to a bare minimum and depending on the pilots skill to make up for any handling shortcomings. This was perfect rational for a high performance racing plane.

    The R-1 and R-2 were very soundly constructed aircraft. The structures were stress analyzed by Pete Miller, he stressed the entire aircraft for 12 Gs positive. After extensive research and testing the R-1 and R-2 were built. Only the best materials were used and workmanship was incredible. The wings were covered with mahogany plywood and then covered again in with "balloon-fabric" for more strength. The fuel caps were now enclosed inside the fuselage and the windscreen was constructed of 3-layered shatterproof glass.

    Perhaps the most unusual feature was the pilot position just ahead of the vertical fin. With a fuselage of just 17 ft. 9in. in length an extreme aft location for the cockpit was necessary to balance the engine and Smith adjustable propeller up front. The R-1 and R-2 were considerably larger than the previous model Z: wing span, 25ft.length, 17ft.9in.wing area, 100 sq.ft. empty weight, 1,840 LB; with 160 gal of fuel and 18 gal for oil.

    The R-1 and R-2 were nearly alike except that the R-1 had the larger, more powerful Pratt & Whitney R1340 "Wasp" engine. It has a diameter of 50-5/8" and a frontal area of 13.98 sq. ft. Nine cylinders, super charged with a 12:1 supercharger and devloping around 800hp. The R-1 was built specifically for the Thompson Trophy race (pylon racing).

    The R-2 was built for the Bendix Trophy race (cross country racing), but it was thought that it would be a strong contender in pylon racing as well. The 1932 R-2 was powered by the very same Pratt & Whitney R985 that had powered the 1931 Model Z, rated at 535hp. The R985 engine had a diameter of 45-3/4" and a frontal area of 11.42 sq.ft. This allowed the R-2 to have a more streamlined cowling and come closer to the ideal teardrop shape.

    The R-2 had an empty weight of 1,796 pounds and a gross weight of 3,883 pounds. With a wing area of 101.9 sq.ft, the wing loading was 38.1 pounds per sq. ft. The power loading with 50 gallons of fuel on board was 4.47 pounds per horsepower, but with full fuel, it was up to 7.32 pounds.

    Other than the engine, the biggest difference between the two aircraft was that the R-2 had two fuel tanks totaling a 302 gallons versus a single 160 gallon tank in the R-1. The R-2 had a 20-gallon oil tank versus 18 gallons on the R-1. The R-2 had a fixed tail wheel while the R-1 had steerable tail wheel. The R-2 also had streamlined running lights in the wings and on the tail for night flights.

    On August 10, painter George Agnoli finished the fancy scalloped red and white paint job on the R-1. On the 12th it was rolled out of its hangar to sit gleaming in the sunshine. Final adjustments postponed the first flight until the following day. On August 13, shortly after nine o'clock, Russ Boardman took off his coat, slipped on a parachute and flew the R-1 to the Bowles Agawam field across the Connecticut river. The performance figures were exhilarating. The R-1 had hit 240 mph without half trying and Boardman felt confident that 300 mph was well within reach.

    Robert and Granny Granville were at Bowles when Boardman landed from the first test flight. As they opened the door of the plane, Boardman looked up at them, grinned and said, "You boys sure build airplanes." His only complaint was that the ship bobtailed during landing approach and apparently did not have enough fin area. Work was immediately begun to rectify that problem by adding two square feet of fin area and an increase in rudder area to match the added fin.

    Russell Boardman prior to first test flight of the Gee Bee Model "R1". Note original small vertical fin and rudder area. (click picture for a larger view).

    Gee Bee Model "R1"(click picture for a larger view).

    The R1 and R2 at the 1932 Cleveland Air races.

  • On Tuesday, August 16, Boardman was severely injured as he spun a Model E Sportster into the trees on the Carew street side of the Springfield airport as he was flying to Agawam to complete the tests on the revamped R-1. With two weeks remaining before the start of the races, neither aircraft had a pilot. Applications flooded the Granvilles from every pilot in the country who had any ambitions of appearing in the Cleveland races. Finally, on August 22, Lee Gehlbach was chosen to fly the R-2. He would ferry the R-2 to Burbank to fly the Bendix race from there to Cleveland. Oil temperature problems were already starting to show up which would plague the R-2 over the next few weeks. Earle Boardman, Russ' brother, was prepared to fly SIark and Ed Granville to Los Angeles and Kansas respectively to supervise the refueling of the R-2 during the Bendix race.

    A stroke of fate interjected a new name into the Gee Bee saga. At Wichita, Kansas, Jimmy Doolittle was test flying his Laird "Super Solution", which had been extensively modified for the 1932 races. When he found that he couldn't get the wheels down, he was forced to belly his aircraft in, eliminating it from further competition, but emerging unhurt. On August 27, when it was apparent that Russ Boardman would be unable to compete in the National air races, Granny made telephone arrangements with Doolittle for him to fly the R-1. On August 28, Doolittle arrived at Springfield. While everyone expected him to take a turn or two around the field to familiarize himself with the new aircraft, dubbed by the press as "The Flying Silo", he simply climbed in, headed west and never altered his course. Less than two hours later the Granvilles received a telegram stating simply, "Landed in Cleveland O.K., Jim."

    Lee Gehlbach indicated his confidence in Number 7 when he told members of the press, "Number 7 is the most wonderful handling ship I've ever flown. Doolittle added his praise of Number 11 by stating. She s got plenty of stuff. I gave her the gun for just a few seconds and she hit 260 like a bullet without any change for momentum and without diving for speed and she had plenty of reserve miles in her when I shut her down.

    Only five planes were entered in the 2,369 mile Bendix race from Burbank to Cleveland and one of them, Clare Vance in his twin boom flying gas tank, dropped out of the race, because of a fuel leak.

    That left Gehlbach in the R-2 and three Wedell-Wiliams racers piloted by Jimmy Wedell, Jim Haizlip and Roscoe Turner. Making good time, Gehlbach's first fuel stop was Amarillo, TX and he got underway with minimal time on the ground. Shorly afterwards, however he noticed oil on his windshield. By the time he reached Illinois it was completely covered with it, so he made an unscheduled stop at Chanute Field in Rantoul, IL, hoping to fix the leak.

    It turned out to be a cracked oil line that could not be repaired in time to meet the race arrival deadline, however, so he filled the oil tank, removed the canopy and flew on to Cleveland open cockpit.

    The time on the ground at Chanute Field ruined his chance to win or finish high in the Bendix and he ended up last of four racers that made it to Cleveland.

    The prize money was quite generous, however, and Gehlbach made $1,500 (equivalent to about $30,000 today).

    At Cleveland the oil leak was repaired and the canopy reinstalled and the R-2 was entered in the Thompson race and qualified at 247.339 mph.

    Gehlbach ran in the 1,000 cu. in free-for-all but cut the first pylon, had to recircle it, and ended up third behind the Wedell-Williams of Haizlip and Wedell at 183.731 mph.He won $262($5,240 today).

    Doolittle fared better in the Thompson trophy race. On September 5, nursing a hay fever attack, he blazed around the pylons at a winning speed of 252.686 mph. Among those who witnessed his victory were his tu-o sons, ten year old John and James Jr. Lee Gehlbach finished fifth, and Bob Hall, the former Granville engineer, was sixth in the field of eight in his Springfield "Bulldog" racer.

    While at Cleveland, Doolittle set a world's land plane speed mark over the regulation F.A.I. threekilometer course that had been set up for a series of speed dashes sponsored by the Shell Oil Co. On August 31, the 35year-old Doolittle averaged 293.193 mph on four runs over the speed course but this did not qualify as an official record since he didn't have a barograph in the plane to confirm that he was below the required 162 feet (50 meters) during his runs. He subsequently made four more runs on September 1, averaging 282.672 mph, just .77 mph short of that required to claim a new record. On his final run it appeared to the horrified spectators that he was about to brush some trees just north of the field. Later Jimmy said, "I was nowhere near them. I must have been at least four feet over them."

    At the Eastern States Exposition in September of 1932, Jimmy, in speaking of Z. D. Granville. said, "He builds a most excellent airplane and it was the airplane that did the job." Finally, in a letter dated September 7, 1932, and addressed to Granville Brothers Aircraft. Doolittle commented, "Just a note to tell you that the big Gee Bee functioned perfectly in both the Thompson trophy race and the Shell speed dashes. With sincere wishes for your continued success, I am, as ever, Jim.

    Lee Gehlbach and the Gee Bee R-2 #7 after an uneventful cross country flight to Burbank to start the Bendix race. (click picture for a larger view).

    In the Thompson the R-2 and the rest of the field of racers were blown away by Jimmy Doolittle in the Gee Bee R1, once again Gehlbach ended up behind the three Wedell-Williams. He finished in fifth place at an average of 222.1 mph and won $500 (about $10,000 in todayís dollars) Doolittle won $4,500 by winning the Thompson.
    The total amount of money brought back to Springfield, MA made the SARA members prosperous and happy.

    Z. D. "Grannie" Granville with the R-1 at Bowles field shortly before Jimmy Doolittle flew it to Cleveland.(click picture for a larger view).

    The R-2 (#7) left. and the R-1 (#11) in front of the Skyways hangar at Cleveland, Ohio in 1932.You can very clearly see the difference between the two aircraft in this photo.(click picture for a larger view).

    Jimmy Doolittle and the Gee Bee-R-1(click picture for a larger view).

    1933 Races

    In 1933 the Gee Bee R-1 had a new 1,860 cid (around 1,000 h.p.) Hornet engine and the Gee Bee R-2 received the 1932 Gee Bee R-l's record setting 740 h.p. Wasp engine and cowling. Also in 1933 Zantford (Grannie) Granville designed a new, slightly thicker wing incorporating flaps and having an increase in wing area to 132 sq. ft. from 100 sq. ft. All of which lowered its landing speed to 65 mph. from over 100 mph. The old 1932 wing was put in storage. This 1932 wing was the one that was used on the 1933 R-1/R-2 hybrid since it was identical to the Rl's damaged wing.

    S.A.R.A. president Russell Boardman had recovered from his accident of a year earlier and was going to fly the R-1 in the National Air Races out in Burbank, CA. Russell Thaw was picked to pilot the R-2. Jimmy Doolittle had retired from air racing as a champion and world-famous celebrity. Lee Gehlbach, in 1933, was flying the No. 92 Wedell-Williams.

    The 1933 National air races were to be held in Los Angeles from July 1 through July 4, with the finish of the transcontinental Bendix race from New York as one of the highlights. After being received at City Hall on June 6 by Mayor O'Brien of New York, Boardman, now recovered from his earlier injuries, and 22-year-old Russell Thaw, in the re-engined R-1, and the modified R-2, left Floyd Bennett field on the morning of July 1, 1933 along with Roscoe Turner, Lee Gehlbach, Jim Wedeli and Amelia Earhart. Thaw took off at 5:52 a.m. and Boardman followed, being the last to depart. Thaw used almost the entire length of the field, dragging his tail wheel as he struggled to get his heavily laden plane into the air. Boardman, with a lighter load and higher horsepower, made a perfect take-off and streaked westward.

    Boardman and Turner had announced that they would refuel in Indianapolis while the others would let their fuel consumption govern their landing places. Preliminary plans called for Thaw to land at St. Louis and Amarillo, but his high rate of fuel consumption caused him to land at Indianapolis. Turner arrived at Indianapolis at 6:06 a.m. and within ten minutes he was once more winging his way westward. Thaw was the next to land. Contrary to many published reports, he made a perfect landing. On all earlier Gee Bees the Granvilles had manufactured their own shock struts. Now their racers were equipped with a commercially manufactured strut. In making a rapid 180-degree turn to get back to the refueling area, one of these struts collapsed and the left wing tip was damaged near the outer aileron hinge as it struck the runway.

    Since it looked as if the damage could be readily repaired, the plane was wheeled into a hangar and work was begun to restore it to flying condition. Boardman was the next to arrive and he chatted with Thaw as his plane was refueled. Then he took off with 200 gallons of fuel on board. At about 40 feet in the air, he lost control of Number 11, and it flipped on its back and crashed, fatally injuring Boardman, who died on the morning of the 3rd, leaving a wife and four-year-old daughter, Jane. Thaw was so shaken that he withdrew from the race at that point.

    Russell Boardman with the modified Gee Bee Model "R-1", A Hornet engine was installed and the rudder had an extension added to it,these modifications were for the 1933 race season. (click picture for a larger view).

    New England Air Museum's: Gee Bee Model R1 replica.(New England Air Museum Photo)

    Gee Bee Model "R-2"Modified for the 1933 Cleveland Air Races. With a new wing with flaps,as well as the Wasp engine and cowling from the R1 and an extension to the rudder.(click picture for a larger view).

    The other entries were also plagued with misfortune. Lee Gehlbach, flying a Wedell-Williams racer, was forced to land near New Bethel, Indiana, with a clogged fuel line, crashing through a fence but emerging unhurt, and Amelia Earhart, in a Lockheed Vega, was forced down in Kansas. Roscoe Turner won the race in 11 hours and 30 minutes, picking up the $5,050 first prize plus $1,000 for setting a new East to West record. Wedell, who finished second, won $2,250.

    It was a horrible blow for the Granville brothers. In a few minutes they had lost both planes and one pilot. Robert Granville recalls, "I guess it was the point where our luck started to go bad."

    Boardman's brother, Earle, also a pilot, was with him when he died. On July 4, he flew Russ' body east to Hartford, Connecticut, stopping to refuel at Syracuse, New York. On July 6, 1933, Russell Boardman was laid to rest in the Miner cemetery in Middletown, Connecticut, while six planes circled overhead and dropped flowers. Among those present was John Polando of Lynn Massachusetts, with whom Boardman had made his long distance flight to Turkey.

    The Gee Bee R-2 was repaired at Springfield in 1933 and while being flown by James Haizlip. Making his third landing, Haizlip found himself floating too far down the 200 ft. runway, he kicked in the right rudder to side slip and kill the airspeed, but this caused one wing to stall, and the Gee Bee R-2 cartwheeled down the runway, rolling itself into a ball. Haizlip escaped with only bruises from the saftey harness.
    The dissapointed Granville brothers tried once more with a hybrid model called the "Long Tail Racer". It used the "Hornet" engine, the R1 fuselage with another section added and the wings from the 1932 R2. This aircraft was built for the 1934 races. It was longer, had a new logo and was expected to easily fly 300 mph.The letters "I F" on the nose stood for "Intestinal Fortitude". Race pilot Roy Minor was chosen to test fly this aircraft, and had a good first flight. But on the second flight he had a landing accident and flipped over a fence. Roy was not hurt, but the same could not be said for the aircraft. Although the aircraft was repairable, the Springfield Air Racing Association saw fit to pull their funding. This ended the Granville Brothers series of racing planes.
    After another rebuild, the Long Tail Racer ended up with Cecil Allen. Despite warnings from Pete Miller and Granville, Allen installed a larger fuel tank well aft of the center of gravity (cg). Granville and Miller feared the cg would be moved be to far aft, making the plane impossible to fly. Ignoring these warnings, Allen took off with the fuel tank full, lost control and was killed. This ended the R-1 and R-2 racers. The Long Tail Racer was never rebuilt.

    "Long Tail Racer" (click picture for a larger view).

    During the fall of 1933, Z. D. Granville, Howell Sliller, and Donald Delackner opened a consulting engineering office in New York City in the hopes of continuing development of certain commercial projects such as four, six and eight place airplanes. As far as racers went, they were left with the shattered remains of the R-1 and R-2. From the remains of the R-1 and the R-2 the Granvilles built another racer, christening the resultant plane "Intestinal Fortitude". It was known as "International Supersportster" Model R-3. The plan was for Roy Minor to fly it in the Chicago races of 1933.

    After "Intestinal Fortitude" was assembled. Granny planned to fly to San Antonio to deliver the prototype Gee Bee Model E Senior Sportster that he owed to a customer in that Texas City. En route. he planned to visit Florida and the Mardi Gras in New Orleans. Approaching a landing at Spartenburg. South Carolina, on February 12, Granny suddenly noticed that there was construction in progress and his only safe landing area was blocked by two workers, As he pulled up, his engine coughed and died and he spun in from 75 feet. Zantford (Granny) Granville unfortunately died en route to the hospital.

    Shortly after Zantford's death, the Gee Bee organization was sold at a sheriffs sale.

    The Gee Bee R-2 Replica

  • The Gee Bee racers of the early 1930's have always fascinated pilots and enthusiast, and a number of people have started R-1 projects (Ron Coleman of Springfield, IL and Jess Shryack of Justin, TX).

    But it was Delmar Benjamin and Steve Wolfe who finally put an R-series Gee Bee back in the air.

    Delmar Benjamin came up with the funding and Steve Wolf had the building/restoration shop and the expertise to build the Gee Bee R2 replica.

    After careful study and visits with Pete Miller the project began on January 1, 1991 and was test flown December 23, 1991.

    Delmar's airshow performances in the Gee Bee R-2 replica proves that this aircraft is fully controllable, capable of hard aerobatics and straight-line speed.

    He has completely destroyed the myth that the R-series airplanes were the worst airplanes ever built. And Delmar Benjamin is probably one of the most superbly skilled pilots of our time. So buy his book and read about building and flying the Gee Bee R-2 replica.

    Gee Bee R-2 Replica.(click picture for a larger view).

  • The following is a transcript of an article from the July, 1933 Aero Digest.

    I would like to thank Scott Brener for taking the time to transcribe and provide this very interesting article.

    Aero Digest magazine
    July 1933

    The Influence of Racing Types on
    Commercial Aircraft Design

    By Z.D. Granville

    The Granville Gee Bee Transport Model C-8 is the result of experience in aerodynamic and structural design and practice that has proved itself on the greatest of all proving ground - the race course. In the years that we have been connected with aviation as pilots, mechanics and engineers, we have been able to collect an invaluable store of experience and information that enabled us to build the 1932 Gee Bee Supersportster in which Major Doolittle succeeded in bringing the worldís land-plane speed record of 294.38 miles per hour back to America. The lessons learned in this racing game are of value to the commercial builder.
    † † † † The two greatest requirements in commercial craft are speed and durability. The streamline shape that proves superior in a fast racing ship is obviously better for commercial use. Structural design that will withstand the terrific abuse of a race course will, in all probability, prove durable when used in a commercial craft. For either racing or commercial craft, durability is a fundamental essential, and with this point in view it is obvious that the engine plays a very important part.
    † † † † The most dependable high powered aircraft engines in the United States are of the radial air-cooled type, which to the laymanís (and also many designersí) point of view are highly undesirable from the point of streamlining and high speed. With the necessity of using a radial air-cooled engine because of its durability features, we began some years ago to investigate the possibilities of streamlining such an engine. Experiments led us to believe that it was possible to streamline an engine of this type in such a manner that it would have no more drag than any other type of engine of equal horsepower. We discovered that it was not nearly so much the frontal area and cross section of an object as the shape that counted for the desired low drag.
    † † † † Our 1931 Gee Bee Supersportster was the first serious attempt to put into practice our theory in this respect. This job with its large frontal area, huge fuselage, presented an unusual appearance and brought hails of criticism from designers and pilots from all over the country. Some predicted that the ship would never fly; others predicted that if it did fly it had no possible chance of winning anything. In spite of this the 1931 job brought home the Thompson trophy and established a new American landplane speed record. The Gee Bee Supersportster of the following year was designed solely for racing purposes and to establish a new landplane speed record.
    † † † † The appearance of this airplane with its large frontal area and huge fuselage, 61 inches in diameter, represented so radically a departure from the usual racing airplane that the design again evoked criticism from the aeronautical fraternity, in spite of the fact that we had proved our point on the 1931 ship.
    † † † † To check our calculations on this job a scale model was built and tested in the New York University wind tunnel. This test proved our theory correct and the ship was built along the lines first intended.

    The Engine

    † † † † The engine selected for the racing job was the Pratt & Whitney "Wasp," Model T3D1, supercharged to 730 horsepower at 2,300 rpm. The ability of this power plant to develop a tremendous overload of horsepower over an extended period of time, together with its horsepower weight ratio, gave this engine a great many advantages.
    † † † † Experience with racing craft in the past taught us that a propeller efficient at high speed is extremely poor on the get-away and take-off, which counts seriously in a race from a standing start and is particularly objectionable in a commercial job taking off with a heavy load. With this in mind we selected a Smith controllable-pitch propeller as the ideal installation which would give us the desired take-off and still hold the motor down to the proper rpm at the proper speed.

    The Fuselage

    † † † † For minimum profile drag coefficient, a streamline body should have a fineness ratio between 2 and 4. Also the maximum diameter should be located at about one-third of the length of the body. With these points in mind the Supersportster fuselage was laid out. The fineness ratio was set at 3.2 and the maximum body diameter was located at 34% of the fuselage length. The fuselage, of course, was not a body of revolution, but approached this. The sections to about 30% of the length were true circles. From this point aft, the sections became ellipses, with the major axis vertical. The disposition of the cockpit near the tail necessitated this. Having plotted a curve of the drag coefficient against the fineness ratio for a series of geometrically similar streamline bodies we found drag coefficient Dc (lbs./sq. ft./mph) reaches a minimum value at a fineness ratio of nearly 2 and increases above and below this fineness ratio. With a low drag coefficient, the fuselage cross-section area could be increased greatly over other type fuselages before the fuselage drags are equal. This allows a large, comfortable cabin for the pilot, and with an eye towards commercial aircraft, permits the use of a roomy interior for airplanes in use on airlines without sacrifice in aerodynamic efficiency. Therefore, passengers can now travel in greater personal comfort without increased cost to them or the airline operator. The fuselage drag may be expressed in the form of a simple equation:
    † † † † Df = Dc x A
    † † † † Df = total fuselage drag in pounds
    † † † † Dc = fuselage drag coefficient in (lbs./sq. ft.)/ mph2
    † † † † A = maximum cross-section area of fuselage (sq. ft.)
    † † † † From data compiled for the comparison of the Supersportster fuselage with the fuselage of other well known types, it was obvious that by careful attention to the particular shape of the fuselage it was possible to get a lower drag coefficient per square foot of area with consequently low drag for the entire fuselage. This was important as far as the racing ship was concerned, but when taken into consideration from a commercial standpoint the beneficial results are two fold:
    † † † † First, a low drag fuselage on our commercial job will result in better speed which means greater range, lower power required and also lowering of flying time on the ship with consequent reduction in operating cost.
    † † † † Second, the possibility of using the large fuselage without added drag also allows us to build a cabin which is roomy and comfortable.

    Wings and Tail Surfaces

    † † † † For the selection of an airfoil for the wing, it was of course desirable to use one with a low minimum drag coefficient and suitable moment characteristics with a small total center of pressure travel. A high value of maximum lift coefficient was necessary to obtain a reasonably safe landing speed and quick take-off. In the racing airplane low drag is probably the most important factor, followed by suitable moment characteristics; while in the commercial job low drag is important from the standpoint of high speed performance, but high maximum lift with consequent good landing and take-off characteristics is most essential.
    † † † † For the racing airplane the M-series of airfoils recommended themselves because of their low drag and small center of pressure travel. The drag of several of the M-series of airfoils at a constant value of lift coefficient was plotted against thickness in per cent chord at 30% chord. For this comparison, a value of lift coefficient equivalent to a speed of 300 mph of the full scale airplane was selected.
    † † † † The lift coefficient equivalent to a speed of 300 mph is
    CL † = † † † † † L † † † †
    † P † † AV2
    † 2
    † † † † L † = † Gross weight of the airplane (2,500 lbs.)
    † † † † A † = † Wing area in square feet (75 sq. ft.)
    † † † † P † = † Density of air (.002378)
    † † † † V † = † Speed in ft./sec/300 † x † 1,467 † = † 440 ft./sec

    Substituting these values in the equation:
    CL † = †
    † † † † † † † † † † † † † † † † 2500 † † † † † † † † † † † † † † † †
    .002378 † x † 75 † x † 3002 † x † 1.4672
    † † † 2
    † = † .1458

    † † † † Seven of the M-type airfoils may be classified as the "stable series" of that series. The center of pressure travels towards the trailing edge as the angle of attack is increased from low to high angle of attack. The M-6 section has the smallest total center of pressure travel, namely 9%. For the Supersportster wing, sufficient spar depth was possible with ordinates of M-6 reduced to 65%. It is believed that the center of pressure travel is not altered by this change, but the minimum profile drag of the wing is reduced. In flight, the center of pressure travel is small, for the adjustable stabilizer as installed on the Supersportster is not entirely necessary. The elevators were found to be sufficient to maintain trim alone throughout the entire speed range and with power on or off. It is therefore believed that a small center of pressure travel is necessary characteristic in racing airplanes.

    † † † † The tail surfaces of a racing plane should be of sufficient area to permit adequate control at stalling speed and also no larger than necessary because of parasitic drag. Furthermore, large surfaces are apt to be oversensitive at high speeds.
    † † † † The tail surfaces were cantilever type of all wood construction, similar to the wing. They were designed for 75 lbs. per sq. ft. with margins of over 100%, which together with the method of attachment on the fuselage at widely separated points gives the desired rigidity. This construction was much heavier than necessary, but we wished to make sure to eliminate vibration due to flexibility.
    † † † † The stabilizer area was 7.5 square feet. A fillet of 2-inch constant radius was fastened to the stabilizer and held against the side of the fuselage by spring tension and travels up and down with the stabilizer during adjustment.
    † † † † The stabilizer control was screw-type, operated by a wheel directly in front of and at right angles to the seat, within easy reach of the pilot, with his eyes still on the course. The stabilizer has 15ļ of travel, being hinged about the front spar. In actual practice, we found that no adjustment was necessary for landing, take-off, or flying, after the proper adjustment was once made. The elevators were controlled by cables from the stick to a bell crank mounted directly below the stabilizer front spar, thence to the elevators by a push-pull tube with ball-bearing joints.
    † † † † The control stick was unusually long and geared down in such a way as to make a small movement of the control surfaces with a large movement of the stick. The control proved to be light and sensitive.
    † † † † The rudder of the racer was somewhat different from the usual in rudder construction and design. It was merely a movable end on the streamline fuselage. From previous experience it was found that a thin rudder acting between the converging streams of air on each side of the fuselage was too sensitive at high speeds if of sufficient size for control at stalling speed. The rudder is nearly 12 inches thick at the hinge-line and the sides of the rudder are therefore nearly parallel to the flow of the air stream on each side. This makes the rudder action soft at high speeds while of sufficient area for complete control at stalling speeds. The actual operation proved sensitivity to be more pronounced at stalling speeds than at high speeds.

    Engine Cowling

    † † † † The engine cowling regardless of type or characteristics should permit sufficient cooling of the engine cylinder heads and barrels. It should also be constructed as to allow smooth air flow around the fuselage and have as large an anti-drag component as possible. At this point, it might be said that a large number of tests to determine the best chord length, angle to thrust line, and fore-and-aft position could be made for the best combination for this particular model. Time, however, was he limiting factor and experience dictated the general lines to be followed for the design of the engine cowling. However, three types were tested on the wind-tunnel model and drag values were obtained for each type - single and double chamber cowlings and one designed to give the nose of the fuselage a streamline appearance; this type was not constructed to function on the anti-drag principle.
    † † † † Results of these tests showed the single chamber cowl to be better than the others as far as drag is concerned. It was believed that cooling would be sufficient under all conditions in which the airplane was to be flown. This cowl was adopted and, it might be added, the cooling was found adequate and the flow of air behind the cowl and along the fuselage was excellent. This fact is attested to by the exhaust smudge on the body.
    † † † † From past experience we expected trouble from the N.†A.†C.†A. cowling, and governed the design accordingly, but in spite of our precaution the cowling persisted in sliding forward. It was held by its leading edge (supposedly the strongest part of the cowling) by turnbuckles. This leading edge was reinforced by a half inch tube rolled into the cowling. In spite of the extra strength of this arrangement, the tendency of the cowling to move forward was so great as to roll the entire leading edge inward, tending to run the entire cowling wrong way out. We found it necessary to reinforce the nine points of attachment as well as to build up the ribs inside the cowling at this point, to hold them from falling back.

    The Landing Gear

    † † † † The landing gear of the racer was a rather conventional type of fork and shock absorber, having an Aerol strut with five inches travel, working on air and oil.
    † † † † The chassis structure of this landing gear forms the flying structure to which the streamline wires were attached. The maximum loads in this structure from landing and the maximum loads in flying were, of course, not applied at the same time, therefore, this structure did double duty.
    † † † † Warner Aircraft wheels and brakes were actuated by the system of full back on the stick with directional control by the rudder pedals. The 6.50-10 Goodrich tires were enclosed in boots which were attached to the wheel forks in such a way that they travel straight up and down with the wheel, keeping in line of flight and keeping the wheel and tire covered to a maximum in all positions. The Goodrich sponge rubber tail wheel was used with a three-inch oleo type shock absorber, the whole unit being contained within the rudder, giving positive ground control when taxiing or landing. The tail wheel was held in line of the rudder by a cam action which was releasable, allowing the wheel to swivel 360ļ on its vertical axis. This made the ship easy to handle in the hanger.
    † † † † This type of landing gear proved not only to be of very low drag, but had fine shock absorbing and ground handling qualities, as well as the ability to withstand a terrific load in rough landings at high speed on rough fields.

    The Cockpit

    † † † † The main reason for situating the cockpit of the racer just ahead of the stabilizer was visibility, inasmuch as the fuselage at this point had changed from the huge circle 61 inches in diameter at the wing butts, to an ellipse 56 inches deep, and slightly wider than the pilots shoulders at the top longeron. This allowed the use of a small cabin which streamlines well into the fin, and at the same time allowed the pilot to look down at the side and around the fuselage at the best angle. The windshield was three piece "shatterproof" glass. The covering from the windshield back to the head rest was Fibreloid, secured through catches making this cover removable by the movement of a small lever on the left side. This allowed the pilot to release the cover in an emergency and exit through the top, or in the case of oiling up the windshield, allowed him to release this cover, and with the windshield fixed in place, fly the ship like an ordinary open cockpit job.
    † † † † Access to and from the cockpit was by means of a door in the side of the fuselage. By means of a lever just ahead of the door, the hinge pins could be withdrawn, and the door itself instantly released. By this means, the pilot, in case of emergency could put his head between his knees, release the belt, and roll over, instantly being clear of everything with the exception of the stabilizer, which, having no bracing of any kind and being right at the door, could not catch or injure the pilot. This gives the pilot two means of exit in case of an emergency. The pilotís seat was adjustable, by means of a wheel on the left hand side, allowing the pilot to adjust himself to the most comfortable position for visibility.
    † † † † The instrument board was fully equipped with navigation and flight instruments. A Lewis Engineering company thermocouple with selector switch was installed, with the Fahrenheit gauge as near as possible in line with the pilotís vision during a flight, where he can easily note the head temperatures.
    † † † † Ventilation of the cockpit was provided by a three-inch flexible tube, bringing fresh air from a scoop just forward of the cylinders on the engine. This stream of fresh air at high velocity is controlled by a knob on the instrument board which forces a deflector plate against the tube outlet, closing off or on, and deflects the air at will. The ventilator behind the pilotís head allowed exit of the air and brings circulation of fresh air to the pilotís face without drafts. The air is exhausted through the joint of the fuselage and rudder.
    † † † † Two gasoline tanks of eighty gallons each were provided, with a shut-off valve at the extreme lower left of the instrument board, allowing either or both tanks, or the twenty-five-gallon reserve to be used. Oil was carried in a twenty-gallon flat corrugated tank installed in the engine compartment.
    † † † † A specially designed throttle, spark, and altitude control, having large rigid knobs and individual friction adjustments was used. This control unit consisted of a lever controlling the Hamilton Standard controllable pitch propeller and also the control for the Smith controllable propeller. Thus, engine controls were in one strong, neat appearing and accessible unit, requiring the use of the left hand only and not necessitating the shift of hands on the stick for any operation.
    † † † † The throttle was of such rigid construction as to allow the pilot to use it as a hand to steady himself while flying along at high speed in rough air. From the gas tank section back, the fuselage turtle deck is of plywood construction, the sides being built up of fairing and covered with fabric.
    † † † † Disappearing handles were provided for use in lifting the tail for any purpose, as was also a rest contained within the fuselage, under which a "horse" could be placed without damaging the fairing.
    † † † † Two hand holes with spring covers opening inward were provided on the sides of the windshield, allowing the pilot to clean the windshield in flight. These holes were ordinarily kept covered to exclude any exhaust gases.


    † † † † In the racer, exhaust gases were deflected to the proper points within the N.†A.†C.†A. cowling by special stacks and allowed to mix with the air passing through the engine and out the rear edge, thus eliminating the possibility of disturbing the air flow around the outside of the cowl.
    † † † † Owing to the bulkiness of the fuselage on both the racing ship and transport, the first impression gives one the idea that the ship is short coupled, as well as having extremely small tail surfaces, which, however, is an optical illusion, as actually the tail area and the distance from the leading edge of the wing to the elevator hinges is greater than used on many of our previous models, including the 1931 racer. The tail surface area in relation to the wing area is greater than standard practice, being 20.75% in the racer, while on the transport job this amounts to 18.25%.
    † † † † The racing ship was designed with a load factor of 12 at high angle of attack with the exception of the tail surfaces, whose load factors were considerably higher.
    † † † † On the commercial job the load factors are 7 at high angle of attack with the exception of the tail surfaces, which are slightly higher. The reason for the difference in load factors is because of the difference in the weight horsepower ratio, as well as the maneuverability. Also, the size of the racer allows for quicker maneuverability and the ship is liable to be subjected to terrific loads due to these maneuvers, or experienced when running into the wash of another ship during a race or flying at high speeds through rough air.
    † † † † Proof of the soundness of this design by actual performance is ample reason for using such features of aerodynamic and structural design in our commercial jobs, and the game of airplane racing today has the same bearing on the commercial aircraft industry of tomorrow that automobile racing has always had on the following automotive industry. Race courses are laboratories and proving grounds of new and better ideas, and pave the way for efficiency and safety in the airplane and automobile of the future.

    Specifications Supersportster
    Model C-8
    Wing span 25 feet 45 feet
    Length 17 feet 8 inches 33 feet 9inches
    Height 8 feet 2 inches 11 feet 6 inches
    Net wing area 75 square feet
    Gross wing area 335 square feet
    Root chord 53 inches 132 inches
    Wheel tread 76 inches 120 inches
    Max. fuselage diameter 61 inches
    Max. fuselage cross-sec 41 sq.feet
    Aspect ratio 6.1 to 1 5.2 to 1
    Incidence 2.5 degrees 2.5 degrees
    Dihedral 4.5 degrees 4.5 degrees
    Weight empty 1840 pounds 3925 pounds
    Racing gross wt. (50 gals.) 2415 pounds
    Maximum gross weight 3075 pounds 7000 pounds
    Total fuel capacity 160 gallons 200 gallons

    Model C-8
    High speed 294.38 miles per hour 225 miles per hour
    Cruising speed 260 miles per hour 190 miles per hour
    Landing speed 90 miles per hour
    Landing speed (with flaps) 50 miles per hour
    Rate of climb 6100 feet per minute 1100 feet per minute
    Endurance, full throttle 2.14 hours 3.08 hours
    Endurance, cruising 3.65 hours 4.5 hours
    Range, full throttle 630 miles 695 miles
    Range, cruising 925 miles 850 miles


    Note:The picture above is a composite of a model of the Gee Bee C-8.The C-8 was never completed due to lack of funding.

    © 1998

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