Howmet TX

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Howmet TX

Category	Group 6 sports prototype
Constructor	McKee Engineering
Designer(s)	Ray Heppenstall Bob McKee
Technical Specifications
Chassis	Tubular space frame
Suspension (front)	Double wishbone with coil spring
Suspension (rear)	Double wishbone with coil spring
Engine	Continental TS325-1 2960 cc two-stage gas turbine mid-mounted
Transmission	1-speed (electric motor for reverse)
Fuel	Jet A
Tyres	Goodyear
Competition History
Notable entrants	Howmet Corporation
Notable drivers	Ray Heppenstall Dick Thompson Ed Lowther Bob Tullius Hugh Dibley
Debut	1968 24 Hours of Daytona
Races   Wins    Poles     FLs    11 21 N/A N/A
Constructors' Championships	0
Drivers' Championships	0

The Howmet TX (Turbine eXperimental) was an American sports prototype racing car designed in 1968 to test the competitive use of a gas turbine engine in sports car racing. Planned by racing driver Ray Heppenstall, the TX combined a chassis built by McKee Engineering, turbine engines leased from Continental Aviation & Engineering, and financial backing and materials from the Howmet Corporation.^[1]

Although not the first attempt at using a turbine powerplant in auto racing, the Howmet TX was the first and is still the only turbine to successfully win a race,^[1] earning two Sports Car Club of America (SCCA) race victories and two qualifying sprint victories during its only year of competition.^[2] The TX later set six Fédération Internationale de l'Automobile (FIA) land speed records for turbines after being retired from racing.^[1]

[edit] Development

Interest in the use of gas turbines as a alternative to the piston engine had been gaining support in the automobile industry during the 1960s. Chrysler had begun limited testing and leasing of their Turbine Car to the public in 1963, while British manufacturer Rover and racing team BRM combined to build a racing car for the 24 Hours of Le Mans that same year. Both cars showed reliability and high fuel economy but were unable to win over the public or to win at Le Mans respectively. By 1967, team owner and car developer Andy Granatelli had created a turbine-powered roadster for the Indianapolis 500 that nearly won the race for American driver Parnelli Jones, but suffered mechanical failures after leading over two-thirds of the event. A similar attempt in 1968 also led to retirement after showing winning potential.^[3]

The McKee Mk.9 chassis

At the same time as Granatelli's turbine debut at Indy, racer Ray Heppenstall began to conceive a design for his own sports car to make use of a gas turbine, improving in some areas where the Rover-BRM had failed several years before. Heppenstall felt that a more simplified design for the chassis could make a turbine-powered car more competitive. Heppenstall originally proposed the car to Allison Engine Company and later to Williams Research.^[4] He eventually turned to fellow racer Tom Fleming for aid. Fleming was at the time vice-president of Howmet Corporation, which provided castings for turbines in the aerospace industry. Heppenstall and Fleming were able to convince Howmet that their backing of a competitive and unique sports car could promote public awareness of the company. Howmet agreed to fund the project, lending their name to the car.^[1]

[edit] Chassis

Heppenstall began the project by purchasing a Cooper Monaco sports car, but later decided it was not the best choice for a turbine and the car was sold off.^[4] Bob McKee, owner of McKee Engineering, was then contracted by Heppenstall to build two cars brand new. The first space frame chassis was actually built from an older McKee car initially built for the Can Am series in 1966, but adapted to house the turbine engine.^[3][5] The second car was built from scratch, allowing it to be purposely designed around the use of a turbine engine, including a chassis 2.25 inches (57 mm) longer.^[1] The chassis were known as the Mk.9 to McKee, but only ever raced as turbines under the Howmet TX guise.^[5]

The Mk.9 was designed around the FIA's Group 6 regulations for sports prototypes, allowing for a completely custom mid-engine layout that was only limited in terms of engine sizes available to competitors. Closed cockpit bodywork with gullwing doors was designed by Bob McKee to shroud the mid-engine layout. Standard double wishbone suspension with coil springs were used with disc brakes on each wheel. A 32-US-gallon (120 L) fuel tank was placed between the cockpit and turbine, housing Jet A fuel.^[3]

[edit] Turbine

The turbines to power the two Howmet TXs were leased from Continental Aviation & Engineering. The TS325-1 gas turbines were prototypes from an aborted bid for a military helicopter contract which Continental was not putting to use at the time.^[6] The loaned turbines weighed 170 pounds (77 kg) and were able to provide 325 bhp (242 kW) and 650 ft·lbf (880 N·m) of torque.^[1] A maximum of 57,000 rpm was able to be reached.^[6]

The snorkel on the roof fed the turbine directly. The original turbine's exhaust pipes exited the opening at the rear of the bodywork.

A two-stage setup used an internal power turbine to drive the rear wheels through the use of reduction gearing. Due to the wide variable output of the turbine, a standard gearbox was not necessary, leaving the Howmet TX with only a single gearing speed. However, the gearing ratios were able to be quickly changed in the differential, allowing the car to be adapted to various circuits. Due to the use of a single-speed transmission, there was no gearing for reverse. Although Heppenstall initially wished to do without reverse, the FIA mandated its use and a small electric motor powered by the turbine was installed, allowing the car to move in reverse.^[1]

The turbine itself used two large exhaust pipes which were directed upwards out of the rear of the car. However, a smaller third pipe was situated off-center for use with a wastegate. The wastegate was designed to eliminate the lag between the driver pressing the accelerator and the turbine increasing its revolutions. Once the turbine was at its maximum revolutions, the wastegate helped regulate the amount of fuel actually entering the turbine, thus increasing or decreasing the power output.^[1]

Although turbines cannot have their displacement measured in the same way as a piston engine, the FIA used an equivalence formula to determine the Continental TS325-1's displacement of 2,960 cubic centimetres (181 cu in),^[6] although Heppenstall has since admitted that the engine was actually above the three litre limit.^[4] This allowed the Howmet to compete in the Prototype Under 3000 cc category of the Group 6 formula.^[3]

[edit] Racing history

Following completion of the two Howmet TXs, the cars were brought to the 24 Hours of Daytona, the opening round of the 1968 International Championship for Makes. Before even entering competition the TX earned attention, and was featured prominently on the cover of the race program.^[7] Although both cars were in attendance, only the newer of the two was entered in the race; the other car was kept as a spare if necessary.^[1] The driving team of Heppenstall, Dick Thompson, and Ed Lowther qualified with a lap time seventh fastest overall.^[8] Several competitors made early refueling stops allowing the Howmet to improve to third place but on lap 34 the turbine wastegate failed to reopen, giving the driver too much power for the corner he was in. This spun the car and it impacted a barrier, forcing the team to retire.^[3]

By the 12 Hours of Sebring a few months later, the TX was able to improve its pace, this time qualifying third, only a second behind a Porsche 907 and a Ford GT40.^[8] The turbine ran reliably at first but as the race continued, debris damaged the turbine and caused it to shake loose from its mounts. The TX was eventually retired after six hours.^[1][4][9] Following Sebring, the International Championship returned to Europe, and the Howmet team followed. They entered the BOAC 500 at Brands Hatch. Wastegate problems once again caused the car to wreck, this time after only seven laps.^[3][10] Staying in Britain, the Howmet team entered a national sprint race at Oulton Park for British driver Hugh Dibley. However, the failure of a starter motor during a pit stop once again denied the TX the possibility of finishing the hour-long event.^[1]

Rather than staying in Europe for the remainder of the International Championship, the TX returned to the United States to contest the SCCA National Championship. Closer to home, the problems with the experimental TX were able to be overcome as the car finished its first race, the Vandergraft Trophy in New Cumberland, West Virginia. Heppenstall drove the car to a second place finish,^[2][3] setting a new lap record for the circuit.^[1] Following a retirement in Michigan, the TX next arrived at the Heart of Dixie event in Huntsville, Alabama. A short sprint race was held on the day prior to the main race in order to determine the starting order of the field. The Howmet TX was able to earn victory in the sprint, allowing it to start on pole position for the main event.^[2] From there, the TX dominated the event and earned another win. These two victories marked the first ever wins by a turbine-powered car in a racing event.^[3]

With the first victory earned by the Howmet TX, Heppenstall was once again joined by Dick Thompson for the Marlboro 300. Once again the car won the short qualifying race to earn pole position, and from there went on to lead every lap of the main event, winning by an eleven lap margin.^[2][3] Feeling that the TX was now capable of taking on European entries, both TXs were entered in the 6 Hours of Watkins Glen, another round of the International Championship. Hugh Dibley and newcomer Bob Tullius were entered in the first car, while Heppenstall and Thompson shared the second. The cars qualified eighth and ninth fastest.^[8] Following early accidents by the factory Porsches, the TX cars were running third and fourth overall.^[3][8] The Dibley and Tullius car suffered a transmission problem in the closing hour requiring the car to crawl around the circuit until the end of the race.^[1] However, the other entry remained on pace until the end, finishing on the podium overall and was the highest finisher in its class. The podium earned Howmet four points towards the International Championship.^[3]

After the Watkins Glen success, the two cars were prepared for an attempt at the 24 Hours of Le Mans, which had been postponed until September. French aluminium company Pechiney sponsored the team's bid at the 24 hours.^[4] The same drivers were assigned to the cars, but their qualifying performance at the Circuit de la Sarthe was hampered by the long straights. Twentieth fastest was the best performance from the two cars.^[8]

For the race itself, mechanical problems appeared early as Thompson's car suffered after only three laps. The fuel system was not providing enough Jet A to the turbine to allow it to produce its full power output, meaning the car had to limp down the circuit's long straights.^[1] While that car continued at a slowed pace, the other suffered a wheel bearing failure two hours later, requiring a lengthy three hour repair. By the sixth hour of the event the car was disqualified by race officials, having covered an insufficient distance of only 60 laps.^[3][8] The remaining fuel-starved TX did not last much longer as Thompson crashed in the Indianapolis corner, flipping the car and destroying it.^[1][3]

With the 1968 season over, Heppenstall planned for the following year, including the development of a new multi-gear transmission to replace the single speed unit.^[4] However, Howmet felt that the program was not providing adequate promotion for the company and decided to discontinue it.^[1][3]

[edit] Land speed records

Howmet decided in 1969 that although the racing program was too expensive to continue, the two cars it owned could still be put to promotional use. Happenstall decided that he would attempt to repair the second TX chassis previously destroyed at Le Mans. The car was extensively modified to adapt new open-cockpit bodywork, earning it the name Howmet TX Mk.II. The new vehicle attempted to break world land speed records for turbine-powered cars. With the TX Mk.II weighing approximately 1,000 kilograms (2,200 lb), the car was able to make attempts at two classes of records thanks to the addition or subtraction of ballast.^[6]

On a road next to Talladega Superspeedway in August 1970, Happenstall drove the TX Mk.II to six records recognized by the FIA,^[1] with the timing recorded by the new International Motor Sports Association (IMSA).

[edit] Later use

Howmet TX chassis #GTP3 running during the 2007 Goodwood Festival of Speed

An Allison 250C18 turbine installed in chassis #GTP3. This unit is smaller and lighter than the original Continental turbine.

In 1971, Howmet ended their promotional use of the two TX cars. The two chassis were sold to Rey Heppenstall for one dollar. However, because the two Continental turbines had been leased to Howmet, they had to be returned once the cars were no longer under Howmet's control.^[6] Heppenstall eventually sold the two chassis.

Chassis #GTP1 was bought by Jim Brucker and stored in his personal collection in California. On display, it featured a mock-up of the Continental turbine in the engine bay.^[1] The car was bought in 2006 by Bruce Linsmeyer of Avon Aero and has been restored with an original Continental turbine. Following restoration, #GTP1 won the Sebring Trophy at the 2007 Amelia Island Concours d'Elegance.^[11]

The second car, chassis #GTP2, was converted from its open-cockpit bodywork back into its original closed-cockpit design in a restoration carried out by McKee Engineering at the behest of new owner Chuck Haines. Original Continental turbines could not be obtained, so a smaller Allison 250C18 turbine was installed.^[6][5] The different powerplant required some redesign, as the exhaust was now vented out of the top of the engine cover instead of out the rear of the car. The wastegate was no longer used, meaning a third exhaust pipe was not necessary. Chassis #GTP2 was completed in July 1996 and has since run in the Goodwood Festival of Speed three times. It was later sold to Xavier Micheron and is now on display in France.^[1]

During Haines' ownership of chassis #GTP2, an uncompleted McKee Mk.9 chassis was discovered. This third chassis, known as #GTP3, was also purchased by Haines. McKee completed the car to original specification in 2000 for Haines. Again, due to the lack of a Continental turbine, the Allison unit was used instead.^[1][5] Haines still owns #GTP3 as of 2008 and has entered the car in historic motorsport events, including the 2007 Goodwood Festival of Speed.^[12]

[edit] References

[edit] Notes

1. The Howmet TX earned two main race wins. The two qualifying sprint wins are not counted toward its overall total.

[edit] External links

Wikimedia Commons has media related to:

Howmet TX

• YouTube - Howmet TX #GTP2 being started at the Amelia Island Concourse d'Elegance