The 917 Longtails
A quick look at the 3 iterations of the 917 langhecks (longtails)
24 Hours of Le Mans. The world's greatest race. A race that progressed the automobile in every way. Power, suspension, tires, braking, aerodynamics, efficiency, and reliability. All major components of a car that get honed to their limits for the race. It is the sculpted aerodynamics that typically indicate the presence of a race car built for Le Mans.
The Mulsanne Straight is a 3.7 mile long straight (nowadays with 2 chicanes) through the French countryside and a true test of a vehicle's top speed. Starting in the 30's, you began to see bodywork of vehicles take a turn away from their minimalistic, and rectilinear shapes towards aerodynamic shapes, influenced by aircraft. The 1937 Bugatti 37G "Tank car" was one of the first to really embrace aerodynamics at Le Mans.
Chassis 001, BBR 1/18
Personally, this swoopy aerodynamic progression peaked with the Porsche 917LH cars. It was one of the last times that aerodynamics at truly high speed wasn't fully understood. Porsche had had some minor success with their 908LH cars, and continued the trend with the new 917 that would replace it at Le Mans.
Of course, the development of the new 917 was rushed. Most of the development was completed with the SERA institute in France. Nothing - to a completed body design took only 8 months; starting in July of 1968 and finishing in February of 1969. They recognized the body wasn't yet perfect, but they had dramatically improved on many issues from the initial designs. They had found a design that included two rear fins and a wing would create the necessary downforce over the rear of the car. The design also had two flaps that would be controlled by the driver using levers to actuate them under braking. The long tail was just a short-tail version that had the long tail section clipped in. All of the first 25 917s would come in this variation. The aero had not been proven on a moving vehicle, but no matter - the car had to meet the 25-vehicle homologation rules by April of 1969.
Chassis 001, BBR 1/18; you can see the crease where the longtail section would be removed to create a short tail
The car was presented to the world in March of 1969. Everyone knew that Porsche was coming with a 908 replacement, but no one knew it would sport the enormous 4.5L 12 cylinder created by in-house genius Hans Mezger. The 917 was released to much fanfare. It was the next step in race car evolution. Porsche had proven to be a real contender, and this car would be a real threat to Ferrari now that Ford was leaving Le Mans behind after the 1969 season.
Chassis 001, BBR 1/18
The reality didn't quite pan out. The only succesful race in 1969 would be the 1000km of Zeltweg where the 917 would place 1st and 3rd. By the end of the first year of the 917, many physical changes had already been made and the new short-tail we all know and love had been created for the 1970 season, ready to dominate Daytona.
As far as long-tail progression went, Porsche was determined to get a new long-tail for Le Mans. They knew with the previous iteration that a long-tail could reach a full 30kph faster than the short-tails on the immense straight. They had to keep iterating the best design for the long tail. More development went on with substantial body-tweaks at SERA, but this time a road car was developed along-side to prove it out.
The rear flaps of the car had been outlawed, and a totally new tail design was created. One of the new cars (chassis 040) was wrecked after aquaplaning. Chassis 041 was then used for LeMans test-day with poor results. The test driver reported back that the car was unstable. Not the increase in performance they expected from experiencing the same thing the previous year. Some minor improvements were made, but another crash, this time with chassis 041 happened less than one month before Le Mans.
The primary Porsche-backed team Gulf-Wyer did not want to race a long tail in 1970 at LeMans after seeing the testing mishaps. This sent chassis 042 to the Salzburg team and chassis 043 to the Martini team. The chassis 042 would sport a fairly simple red-on-white livery in contrast with the chassis 023 (and winning car) white on red livery we all know quite well. Chassis 043 is what we see here, with one of the greatest liveries ever created for the 'hippie car'.
1970 saw the first Indianapolis start at Le Mans - with the drivers in their vehicles canted out on the pit straight. The chassis 042 car had proven itself in qualifying, sitting on pole with the gulf-wyer short tails right behind. The 043 chassis car had qualified 12th on the grid. The 042 longtail would lead much of the race, swapping with one of the gulf cars much of the race. Sadly, it would break a valve-spring and was taken out of the race. Heavy rains descended upon the race and either took cars out, or slowed them dramatically. In the end, the short tail lead by Salzburg would take the win with the long tail 043 hippie car taking 2nd. Porsche had certainly solved many of their issues with the 917 at this point, but more work was needed on the longtails.
Not waiting for the season to be over before more development, the new longtail design started development weeks after Le Mans in 1970. Chassis 043 was sent to the Stuttgart wind tunnel for refinement and body development. Not only was the body fully changed from the 1970 bodies, but much of the suspension was also adjusted to ensure stability on the fast track at Le Mans.
By the time the 1971 Le Mans had come, the new long tails were ready. At testing, they proved themselves to be just as stable as the short-tail cars, but faster on the straight. The goldilocks point had been found for Porsche.
Starting at Le Mans, the 3 long tails (chassis 043, 045, and 042) would take the first 3 positions on pole, respectively. Rodriguez had already shown he could run 6 seconds a lap faster than the fastest short tail. 043 would not only break the speed record in qualifying, but also set the fastest lap time ever recorded at the track. 043 and 045 would wear the Gulf colors (John Wyer was now convinced the long tails were worth the risk) and 042 that raced with Salzburg the prior year would wear the martini colors shown here.
Of course, Le Mans is a fickle race. None of the long tails would finish. All due to mechanical failures. Despite all of the progress made to make the long tail utterly dominant, a short tail would once again take the win. This car was also special, sporting the only magnesium chassis of any 917 and making a distance record that would take 39 years to break.
Leaving its mark
The bittersweet history of the 917 longtails would show the world that it didn't require crazy extended bodywork to win Le Mans. Aerodynamics would progress significantly over the next few decades and show that downforce could be achieved with low drag without the excessively extended tails. Porsche proved the long sleek recipe could work, if only the mechanicals kept up with the aero during the race. In the meantime, Porsche would continue on to create mega-powered cars with insane downforce for the Can-Am series and for Interserie that would push the limits of downforce.
In the images here, you can see the physical changes that went on between the 3 iterations of the 917 Longtails. Interesting to see how the fronts and rears saw the most significant changes. The removal of the glass engine cover is also an interesting one after 1969. Let's see them side-by-side:
You can see the evolution well here. Swoopier with each gen. Different rear intake methods for each. 70 and 71 share a similar wing and tail. Fender covers for 71. Side exhaust removed after 69
All versions sported different headlights. Front intake enlarged with each year and the NACA duscts removed for 1971. Canards removed after 69 and fender vents added in 71.
Thanks for reading and cheers everyone.