The Porsche That Had an Inflated Chassis

this porsche had a chassis that was inflated with nitrogen it was incredibly light which was down to some ingenious design tricks to take weight saving to the next level the chassis was made of extremely thin aluminium tubes and used the nitrogen in a really interesting way but more on that later porsche used exotic materials and even filled some of the other chassis tubes with oil saving the way of an additional oil tank and pipes weighing only kilograms and having nearly 1000 brake horsepower it was an absolute rocket ship it was 30 miles an hour quicker on the straits than anything else and absolutely dominated le mans well whilst the car was on the tarmac it was a real handful to drive and led to some terrible accidents but porsche managed to fix these strange problems by actually examining the pattern of splatted flies on the car it's the porsche 917 one of the most iconic cars in racing it used some of the most advanced engineering techniques of its time and was porsche's first car to win at le mans and with 19 overall wins and 108 class victories to their name they are now the most successful manufacturer ever to race at le mans so what clever engineering tricks did porsche use to forge new limits and create one of the greatest racing cars ever firstly while the 917 was designed to work at a variety of circuits the main prize for porsche was of course le mans it was extremely streamlined and had a lot of power along with most of the cars in that era they were designed for out and out top speed to make best use of the nearly four mile long straight at le mans it had a flat 12 engine where rather than having the cylinders upright and making the engine tall they lay horizontally this allows the engine to be short and wide allowing it to be mounted lower in the car this helps with handling by keeping the center of gravity low the engine block was made from magnesium alloy as well meaning despite its size it was very light but the real clever bit was the space frame chassis that the engine was mounted to today's breed of sports prototype cars mostly use a carbon monocoque but this porsche used a space frame a slightly more primitive and simple system but equally as impressive a space frame is essentially a frame of metal tubing welded together it relies on the strength of a triangle as each tube is welded to at least two others forming a frame of many triangle shapes this system means that each tube is theoretically only loaded in tension or compression so no bending forces this means that each tube is loaded in its strongest direction all of the time the real amazing part is in the shape of the frame if you think about it a chassis is just there to transmit forces things like the force from the wheels as well as managing the weight of the components like the engine and the fuel tank so the engineers would have calculated the forces they would expect during a race and from that work out how strong each tube needs to be they then would specify the size of each tube to carry this load choosing the lightest tube possible for each part this isn't especially hard today with modern software however calculating accurate loads for each tube is extremely difficult with each tube working together to support the rest the space frame also has to be stiff if the chassis is stiff the behavior of the car can be well controlled with all of the car's movements for example roll being controlled by the suspension if the chassis is flexible this can't be done and often leads to a car that handles horribly and is difficult to control the geometric shape of this car's space frame is so well designed that it's made of tubes that are often less than two millimeters thick porsche used their own aluminium alloy for the tubing it was specially designed for this car to be as strong and light as possible it was extremely expensive and had to be welded together in a tightly controlled environment due to the extreme temperatures when welding it can actually change the structure of the metal this often makes the material brittle and leads to cracks forming when hitting a bump on track so porsche also meticulously heat treated the 917 chassis to get the optimal material composition making it extremely strong often when making chassis or other vital components engineers design in a safety margin essentially making the part slightly stronger than it needs to be this is always a balance have a stronger chassis and less risk of failure and it's heavier or push the limits and have a lighter and quicker car that could fail porsche definitely pushed the limits with the 917. they had such tight margins that the chassis was often used for only one race weekend as the material would fatigue and begin to crack due to the insane forces from 24 hours of pounding around le mans the chassis was also only strong enough when in absolutely perfect condition the smallest crack in the chassis could be a real problem the extreme loads and vibration means that these cracks have the potential to grow it's a bit like when you bend a plastic ruler too many times cracks get bigger and bigger until it snaps these cracks can get so big that they break one of the tubes this would then overload the other tubes create more failures and potentially end in a massive crash so porsche came up with an ingenious solution to solve this they pressurized the entire space frame with nitrogen this meant that they could check the pressure and be sure that there were no cracks or floors in the chassis if you still had pressure you were good to go they used nitrogen as it won't react with the metal and can't damage it all of this meticulous design and manufacturing meant that the entire space frame only weighed 42 kilograms this was over a hundred kilograms lighter than the steel frame of their main competitors ferrari this meticulous weight saving meant the porsche was so tricky to manufacture that they often got it wrong incredibly porsche threw away four space frames for everyone that ended up being used and the porsche engineers didn't stop at that instead of having separate piping between the oil pump radiator and the engine they actually filled the space frame tubes with oil saving weight as they didn't need additional tubing between the radiator at the front of the car and the engine at the back however they removed this in the second version of the car as the drivers were complaining of extreme heat in the cabins from the hot oil in the tubes porsche were pioneers of using some exotic materials all with the aim of saving weight magnesium was used for the uprights and the wheels as well as making the entire steering column from titanium it was extremely advanced for the time however you can now find titanium in anything from a plane to a wallet that's why you should check out today's sponsor the ridge wallet they make slim wallets from exactly the materials you would find in these incredible race cars check them out with the link in the description and use code driver 61 for 10 off all of this weight saving meant the 917 only weighed 895 kilograms and was the lightest car on the grid that year so how did it get on at le mans the insanely quick on the straights and by far the fastest over a lap it turned out that they were this fast partly by mistake and due to this mistake the cars were incredibly difficult to drive the shape of the car meant that the airflow wasn't flowing correctly instead it broke away from the body and wasn't flowing over the rear wing at all which obviously created big problems at speed this meant that both the drag and the downforce were significantly reduced and that was half the reason the cars were 30 miles an hour faster down the straits the 220 mile an hour speeds meant the car actually created lift at the rear to make it go very light and was extremely difficult to drive luckily they never got airborne like some of the incidents we've seen over the years but it got close we saw a similar effect in the nascar issue we spoke about in a previous video drivers complained the car would wonder all over the molson strait and that they could see the sky in the rearview mirror at times at the time the mausoleum straight didn't have the chicanes that it does today it meant that a loss of the lap time was made up on the flat out sections and so top speed was absolutely everything the bravery of these guys has to be respected compared to today these cars offer little protection to a driver and had top speeds that are very similar to f1 keeping your foot pinned at 220 miles an hour down a bumpy muscle straight in the dark whilst the car is wandering all over the road would indeed be a massive challenge but the 917 had a lot of issues none of the cars finished the race the works porsche made it to the 22 hour mark and was in the lead by 50 miles when it sprung an oil leak and had to retire however the driver richard atwood said he was pleased to retire the car he said it was a monster undrivable and extremely dangerous after the race the engineers noticed something strange the front of the car was covered in flies as expected but the rear of the car was not this was extremely unusual and this was when they realized the air was detaching from the rear of the car which was the reason for its instability porsche went back to the drawing board to fix these issues they came back with a new variant of the car the 917k it had a larger rear wing and redesigned rear body work this cured the issue with the lift at the rear but significantly increased the drag it slowed the cars by over 30 miles an hour on the straights however this meant for much more grip around the rest of the circuit and it was immediately four seconds a lap quicker at le mans after the aero problems were solved the 917 was a complete car it won the majority of the races it competed in and won le mont two years in a row the first of 19 for porsche making them the most successful manufacturer ever at le mans the 917 also set one of the longest lasting records at le mans an average speeds over the entire 24 hours of 138 miles an hour including all of the pit stops the car was driven by a young doctor helmut marco and his teammate if you enjoyed this check out these other videos i think you'll love click the video and i'll see you in the next one consider subscribing to to help support the channel and keep us making this content cheers and i'll see you next time

Channel: Driver61

Views: 796,017

Rating: 4.9442439 out of 5

Keywords: Formula 1, Driving, Coaching, Motorsport, Engineering, F1, Racing, Incredible Motorsport, Driver61, Porsche, 917, 917K, LeMans, WEC, World Endurance Championship, Design, Magnesium, Titanium, Ridge Wallet

Id: -TS7qF_cRao

Length: 11min 1sec (661 seconds)

Published: Wed Dec 02 2020

Reddit Comments

[u/RobertGracie]

Just shows you what Porsche did to make that car fast AF it was crazy and then when they took that car to the USA they strapped two TRUCK turbochargers to it to create the unholy satanic 917/30 Spyder with almost 1600bhp! in 1973! and proceeded to kill the Can Am series with it!

[u/-FlyingF1nn-]

This car is amazing to drive in racing sim Assetto Corsa, 917 K.