Tehnika

[alpiner]

Ovo je moglo i u vesti, ali da otvorimo temu..

 

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FIA opens F1 tenders for brake systems and wheel rims

 

The FIA has opened tenders for standard brake systems and wheel rims that are due to be included in Formula 1 from the 2021 season onwards.

In two years time, Formula 1 cars will face a major overhaul as the FIA aims to cut down on areas that teams spend a lot of money on for minimal performance gains.

A way to acheive this is to introduce 'standard parts', which are parts of the car that are the same for each team. Earlier in the year, a tender for standard gearboxes was launched. Now, two more have been launched for brake systems and wheel rims.

The wheel rim tender has been opened for 18-inch rims, with a precaution that the width of the rims may change slightly for 2021. For this, each team will be supplied with a minimum amount of 60 sets per year.

The braking system is split up into two parts, and these are:

- Brake pads and friction discs. A current provider of these parts is Brembo, who supply an average of 140 to 240 disks to each team per year.

- Brake hydraulics, the master cylinder and brake-by-wire components. Brembo supply 10 calipers to each team per year currently.

All of the tenders must make sure that the parts are suitable for use in Formula 1, and that they live up to the performance demands of the sport. They all must be equal specifications so that they comply with the idea that they are 'standard parts'.

Formula 1 managing director, Ross Brawn, says that the scope of the standard parts in Formula 1 will be much greater than what has currently been tendered.

"There is a lot of stuff we have common ground on. There is some stuff we all agree shouldn't change and there's stuff in the middle being argued about. Everyone makes their own fire extinguishers. It's a nice technical challenge, but it doesn't add performance. We can standardise those and help reduce the costs."

The FIA currently has a deadline of the end of June to finalise the 2021 regulations with the teams. However, there has been talk around the paddock that this could potentially be delayed until later in the year.

 

[alpiner]

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F1 2020 clutch changes to make starts more driver-dependent

 

The FIA has introduced a raft of changes to the clutch management in 2020’s Formula 1 technical regulations, increasing the difficulty for the drivers at the race start.

Along with making pull-type paddle-activated clutches mandatory for each driver, the clutch signals used by the standard ECU will also be heavily monitored by the FIA to limit any advantageous mapping.

Should a team wish to use two clutch paddles on the steering wheel, each paddle must now be identical in form, motion and mapping - and drivers may be asked to demonstrate that both paddles work identically.

Furthermore, the paddle must work linearly with the clutch - meaning that the drivers’ actions must be wholly representative of the engagement of the clutch.

Article 9.2.1, section F in the technical regulations states that: “To ensure that the signals used by the FIA ECU are representative of the driver’s actions, each competitor is required to demonstrate that the paddle percentage calculated by the ECU does not deviate by more than +/-5% from the physical position of the operating device measured as a percentage over its entire usable range.”

This ensures greater responsibility is placed on the driver at the race start, meaning that there is the potential for greater variation off of the line.

Further changes have been made to stamp out the effect of oil burning within the car, creating more stringent rules for the transfer of oil to the powertrain.

This comes in the definition of the auxiliary oil tank (AOT), of which only one may be included within the car. This, and the pipework connecting to the engine, cannot exceed 2.5 litres - and must be solenoid controlled.

The amount of fuel outside of the survival cell has also been reduced from 2 litres to 0.25 litres, stopping any fuel flow trickery or mixing of oil with fuel in other areas of the car.

In addition, the FIA has also made changes to the regulations restricting rear-view mirrors, enclosing them in a smaller box to minimise the aerodynamic gain that can be taken from them.

These have also been moved further inwards, following suggestions that the 2019-specification mirrors offer limited visibility, and must now be 30mm closer to the survival cell and 40mm lower down.

https://www.motorsport.com/f1/news/f1-2020-tech-regulations-clutch-oil-burn/4379375/

[MetalHead]

Ne priznajem ovu temu dok se Downforce ne upise u nju... 😎

(pokusavam da ga prizovem) 

[Mickey]

Gledajuci sjajan klip na temi Senna koji je postovao Dasubo, u kome voze stari Senin Lotus i koji se startuje sa komprimovanim gasom, interesovalo me kako se danasnji bolidi startuju. Evo clanka sa motosport sajta da procitaju svi koje to zanima.

 

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Starting a modern turbo hybrid Formula 1 engine is not excessively complicated but it requires a lot of people and to follow a very strict procedure.

 

Motorsport.com talked about starting a Formula 1 engine with Bob Bell, technical adviser at the Renault Sport F1 Team.

 

Due to its extremely tight tolerances, a cold F1 engine cannot be started without any sort of preparation.

“Starting an engine is not that complicated. We must make sure that we have the right people to check the telemetry from the car so to see if it’s doing the right thing,” Bob Bell told Motorsport.com.

 

“It certainly requires more people than it used to be when we simply had a squirt bottle of acetone and a bottle of compressed air.”

It all begins by gradually warming up the engine block, gearbox, radiators and ancillaries to their operating temperature.

“We need to pre-warm-up engine to get it close to its operating temperature,” Bell explained. “We can do that with pre-heating systems, like circulating hot water in the block. The heating system is placed aside the car and connected to the cooling circuit.”

Once the engine has reached the desired temperature, one mechanic fires the electric starter several times with the engine off to circulate oil in the block, and bring the fuel and cooling circuits to the desired working pressure.

After that’s completed, the power is switched on, the starter is turned on and the engine comes to life. The sensors send temperature, pressure, position and speed data to laptops that are connected to the car.

“The thing we have to be very careful is to bring it to the right temperature, and making sure that when it’s running at low rpms and idling that it’s doing the right things as we would expect, that it’s behaving correctly. Then, the computer launches a programme that will automatically warm-up the engine by revving it according to a pre-set sequence,” Bell added.

“Once the engine is running, we have to let the hydraulics warm-up, because things like the power steering, the brake-by-wire don’t function correctly unless they are running at the operating temperature. We then have to do shift checks with the gearbox to make sure that it’s changing gears properly, check that the clutch activates properly, and more,” he explained.

Bell then stated that the hydraulic circuit is a crucial component of the car.

“We use a shared hydraulic system, so there’s only one hydraulic system on the car,” he declared.

“But then, the chassis side of the hydraulics is as sensitive to contamination than the hydraulics that controls the engine. What we do to filter the fluid and look after it with aerospace standards, like what you should expect from a modern aircraft. And that’s quite crucial because it doesn’t take much to stop an F1 car from running properly.”

The British engineer added that it’s quite easy to damage a modern F1 engine.

“What you can’t do is leaving it running for too long with no air passing through the radiators, particularly if the car stops on the track. It’s a matter of a minute or so before you run into big problems.”

Since each driver must contest the entire F1 season with just three engines, the emphasis is (obviously) put on reliability. “We target an endurance cycle of 7,000km for each engine,” Bell admitted.

“That would be ideal. However, if you can get the engine to live just under 6,000km, that’s pretty good. We set a target that is above that to give us a margin, and obviously that’s not much in road car engine terms. It’s surprisingly difficult to get engines to consistently live to that life cycle.

“We have so few engines now, not just those on tracks but also to save money, we don’t want to have to build any more engines that we have to put them on the dyno to test. We don’t have a very big statistical sample size to reliably gauge engine life.”

 

Originalni sajt

[Mickey]

Ne znam gde da stavim ovo pa rekoh ajde u tehniku, podsecajuci se na Menslov Vilijams iz '92, naleteo sam na ovaj clanak. Prelep bolid!

 

Originalni sajt

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The car that rewrote F1’s record and rule books: Nigel Mansell’s 1992 Williams-Renault FW14B

Kurt Ernst on Mar 14th, 2019

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1992 Williams-Renault FW14B/08. Photos courtesy Bonhams Auctions.

In 1991, its debut season, the Williams-Renault FW14 won seven of 16 races on the Formula 1 calendar, but mishaps and mechanical issues kept the team and its drivers from earning championships. In the off-season, the FW14 evolved into the FW14B, which would go on to win 10 races in 1992, including a record-setting nine by world champion Nigel Mansell. Chassis FW14B/08, which Mansell drove to five wins and six poles on his way to the title in 1992, will be crossing the auction block at Bonhams Goodwood Festival of Speed sale, taking place on July 5, 2019, at the firm’s New Bond Street facility in London, England.

The FW14B was a technological masterpiece, and perhaps the most complex F1 car ever created. Taking advantage of gaps in the FISA’s rulebook, the Williams-Renault was equipped with a cutting-edge active suspension (developed in partnership with AP Racing), a semi-automatic gearbox, electronic traction control, anti-lock brakes (late in the 1992 season), electronic data logging, and an exhaust-blown diffuser to supplement rear downforce. Power came from a 3.5-liter Renault V-10, widely believed to be among the most powerful engines on that season’s starting grid.

Active suspension wasn’t new to Formula 1, having debuted in the 1983 season with the Lotus Type 92. An evolution of the technology developed for its road cars, the active suspension used on the Lotus F1 car had little impact on the team’s performance, which was best described as “dismal.” (Of note, however, was the team driver tasked with developing the system — Nigel Mansell.) It would take until 1987 before an F1 car equipped with an active suspension posted a race victory, and that year Ayrton Senna posted two for Camel Team Lotus Honda. At Williams, driver Nelson Piquet helped to develop an FW11B with active suspension, while teammate Mansell chose to stick with the more predictable — but slower — conventional setup, leery after his oft-terrifying experience with enhanced suspension at Lotus.

Such technology can have many components and many functions, but by the time the FW14B was launched in 1992, the primary function of active suspension was to keep the car level, at a consistent ride height, regardless of speed or side load. Not only could the FW14B’s active suspension trim the car, but it also served as an anti-roll bar and could be used (in conjunction with traction control) to limit understeer and oversteer. The tradeoff was precise feel communicated via the suspension to the driver.

As Patrick Head, technical director of Williams-Renault during the FW14B’s development, explained to Motorsport magazine,

Our active control responded to changes in load distribution, but there was always a small period before the system corrected, and during that period the usual feedback to the driver was not present. There was a fraction of a second delay and it felt to the driver as if he didn’t have roll stiffness or roll resistance.”

To put this in less technical terms, taking a corner in the FW14B required a bit of blind trust on the part of the driver. At turn-in, handling was vague, yet confidence in the system — and fast hands to catch a momentary slide — paid big dividends in lap times. Mansell eventually acquired a degree of trust for the active suspension, which proved well-suited to his hard-charging style of driving. Teammate Patrese, on the other hand, was more sensitive to a car’s feel, and had a harder time adapting to the system.

At the season-opening 1992 South African Grand Prix, Mansell put the FW14B (nicknamed “Red Five” for his number and chosen color) on pole, claimed fastest lap, and won the race, with teammate Patrese finishing second. Ultimately, Mansell would earn an astonishing 14 poles in 16 races (with Senna being the only non-Williams driver to earn a pole the entire year, in Canada), with a record-setting nine wins, one more than Senna had achieved in 1988. Patrese scored a single win, at the penultimate race in Japan, but delivered six second-place finishes for the team.

At season-end, Mansell had amassed 108 championship points, nearly doubling that of his teammate and second-place finisher Patrese, who wrapped the year with 56 points. Williams-Renault easily won the constructor’s championship, accumulating 164 points to second-place McLaren Honda’s 99. Still, nothing sums up the dominance of the FW14B more than one simple fact: Its replacement, the FW15, was ready for competition mid-season, but never deployed because the FW14B was so fast and reliable. (A revised version, the FW15C, was raced in 1993.)

The reign of the FW14B did not go unnoticed by other teams and, ultimately, the FISA, which governs Formula 1. Afraid that rapidly emerging technology would only widen the gap between well-funded teams and those with more modest budgets, it passed an edict in February 1993 banning electronic driver aids as of the 1994 season. Briefly, F1 had reached a technological peak, legislated out of existence in the name of cost-containment.

Chassis FW14B/08, the car on offer at Goodwood, was driven by Mansell in seven events over the 1992 season, plus one practice session. It carried the world champion to pole positions in South Africa, Mexico, Brazil, Spain, San Marino, and Monaco, with corresponding victories in all but Monaco (where he finished second). As of race nine, the 1992 British Grand Prix, the car was turned over to Patrese (and thus named “White Six”). Patrese would drive it in six events, earning a pole position (in Hungary) and two podiums (Britain and Belgium).

The car was damaged in a minor crash during the Portuguese Grand Prix but repaired and added to the Williams-Renault collection at the end of the season. It eventually found its way into private hands, but remained a static display until 2017, when it was brought out for exhibition laps at Silverstone in honor of the Williams team’s 40th anniversary.

Given FW14B/08’s racing record and historical significance, Bonhams is predicting a selling price of £3 million (currently $3.89 million) when the F1 car crosses the auction stage in London this summer. For complete details on the Festival of Speed sale, visit Bonhams.com.

 

[MetalHead]

FW14B i FW15C su verovatno tehnoloski najnapredniji bolidi ikada (uzimajuci u obzir eru iz koje dolaze). 

 

Ah to su bili dani... 

 

Nego, jel neko za to da skupimo neke donacije pa da kupimo mi ovo? 🙂 

[Hertzog]

Mercedesov i Ferrarijev pod

[Radoye]

 

Pazi kako je F1 bolid ogroman, uvek su Leman prototipovi bili mnogo veci od bolida-jednoseda a vidi sad ovo! 😮

[alberto.ascari]

MGP, prednji levi točak. Kako ovo sve zajedno radi, pitaj boga...

 

 

[alpiner]

This is what Formula 1 cars will look like in 2021

[Hertzog]

Poprilicno lice na bolide FE

[Radoye]

https://www.racefans.net/2019/09/18/where-have-all-the-single-seater-race-car-builders-gone/

[Radoye]

https://www.formula1.com/en/latest/article.aldo-costa-on-engineering-ferrari-and-mercedes-f1-dominance.7bmB2wMaizAUPeCXvvYj6M.html

 

 

Edited November 27, 2019 by Radoye

[MetalHead]

Joooooooj sto ne volim podcast-e. Ne znam zasto ali ne mogu da se fokusiram na pricu. 

 

Zato "slusam/gledam" odlicni @Mairosu-ov kosarkaski podcast na Youtube-u a ne na Soundcloud-u ili gde vec kaci. Jednostavno, iako ne buljim u video njih sa slusalicama, lakse mi je kada ponekad bacim pogled, kada je neki momenat u prici kada zelim da vidim i neku emociju na licu, ili jednostavno da vidim lice tog ko prica, kako izgleda sada, ili kako izgleda uopste. 

 

Da li bih znao da prepoznam Costa-u?! Nema sanse... 

[alpiner]

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F1 will not go all-electric – Symonds

Andrew Maitland

November 25, 2019

 

Formula 1 will work to become the authority in the area of biofuels rather than join Formula E in the world of electric power.

That is the view of Pat Symonds, a former F1 engineer who now works with the FIA.

“Formula 1 didn’t invent the hybrid, but Formula 1 showed what a hybrid could be and it moved people’s perceptions of what a hybrid is capable of,” he said.

Currently, the rules mandate a 5.75pc biofuel mix, and that should increase to 10pc for 2021. But Symonds indicated that the eventual goal is 100pc.

“The path to that is not completely clear at the moment, but in

partnership with the FIA and with the help of the engine manufacturers and the fuel companies, we are looking at the way forward,” he said.

“What we cannot do is carry on digging those (fuels) out of the ground. We’re going to have to somehow synthesise them and that’s what we want Formula 1 to explore and hopefully to lead.”

Symonds said F1 will not simply follow Formula E’s lead with all-electric power.

“What we can do is we can show the world that there are alternatives to electric power and there are alternatives to storing electricity in heavy and, I have to say, somewhat dirty batteries,” he said.

 

[Dzoni_m]

Nije F1 tehnika, ali Gordon Mari objasnjava svoj novi auto, pravi naslednik MCL F1.

Pure car porn.


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[Radoye]

Igrarije sa kontrolom ogibljenja na Indi bolidima:

 

https://racer.com/2020/08/14/an-inside-look-at-indy-weight-jacker-tricks/

[Jamesdin]

WTF?

https://www.gpblog.com/en/news/66195/-ferrari-could-have-the-only-legal-power-unit-at-the-moment-.html

[Dzoni_m]

Pa da. Bilo je pitanje momenta kada ce izvuci zeca iz sesira. Vec smo videli natpise u italijanskim medijima kako “Ferrari jedini vozi legalan pogon”. Posle istrage FIA sve je provereno i FIA sada tacno zna sta da trazi. Bice ovo bolno otraznjenje za ostatak grida.


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[Jamesdin]

Realno, ovakva pravila su sranje! Suviše su restriktivna.

[Dzoni_m]

Odavno se to prica. Pogledaj samo pravila za 2022. Kretenizam. Bukvalno cemo dobiti identicne bolide za koju godinu. A to nije F1. F1 treba deregulaciju. Poptunu. Ovo sto sada rade je tipicno Americko proseravanje kako svi treba da budu ravnopravni u performansama. Jebes takvu F1 

[Radoye]

 

[Radoye]

 

[zoran59]

Nije F1, ali odlican i edukativan tekst o motorima (F1 motori se nesto malo pominju na nekoliko mesta) mojeg omiljenog autora. Enciklopedija problema sa visokim obrtajima, u kratkom clanku.

(ako niko drugi, @DASUBO ce mozda komentarisati)

 

Kevin Cameron iz Cycle World magazina:

Seeing Red

What limits and lets motorcycle redlines climb higher and higher?

 

By Kevin Cameron September 24, 2021

 

Cycle World reader “RedRadio” expressed interest in how the peak-rpm capability of motorcycle engines has risen so high.

A big, slow-turning engine of 110ci/1,800cc giving peak power at 5,000 rpm, and a little 37-inch/600cc four revving to 15,000 arrive at similar horsepower by different routes. Understanding these two paths requires an appreciation of the factors limiting and permitting high-rpm operation.

First, consider why a builder would want to raise an engine’s rpm limits. The three variables from which we compute horsepower are:

1. Cylinder displacement, which tells us what volume of fuel-air mixture our engine can, in theory, pump into itself.

2. Stroke-averaged net combustion pressure, which in turn depends on how well the engine breathes, what its compression ratio is, and how efficiently it burns its fuel-air charge. A much bigger increase can be achieved here with supercharging or turbocharging, but neither has ever found much use in production bikes.

3. RPM, which measures how often our engine can perform the power-producing cycle.

Displacement is often set by a racing class or commercial segment, such as 600 Supersport or 450 motocross. Techniques for maximizing No. 2 above are known to all manufacturers and tend toward a common level. That leaves us with No. 3, raising an engine’s redline, as the most effective tool for boosting horsepower.

Problems With Raising the Redline

The classic problems with increasing operating rpm are numerous. First (with four-strokes) is the difficulty of making the valve train accurately follow the contour ground into each cam lobe. When an engine reaches its limit in this respect and the valve train fails to follow the cams, it experiences “valve float.” Uncontrolled valve motion leads to destructive effects such as valve-to-piston impacts. It is typical in high-performance engines for valve-train parts to be made lighter at each model change, often requiring use of upgraded materials.

Early cam lobes had simple geometric shapes that imposed hammerlike accelerations on valve trains. It would take years before improved lobe shapes applied loads to valve trains in a more gradual and survivable way.

For a given valve-spring pressure, the lighter the valve train, the higher the rpm at which the system can accurately follow the cam lobe. The late English F1 designer Keith Duckworth enunciated his “square root of two” principle, which states that when you abandon two valves per cylinder in favor of four, you divide your problems by the square root of two, which is approximately 1.41. In a spooky confirmation of this, consider the 10,250-rpm peak of Rob Muzzy’s Z1 Kawasaki-based 1,000cc two-valve 152 hp Superbike engine of 1983 with the 14,600 revs presently used by Jonny Rea’s one-liter ZX10RR four-valve World Superbike engine. The arithmetic is 14,600/10,250 = 1.42. Both of these engines employed the very best metal valve springs of their time.

The more parts there are in a valve train, the heavier it is, and the greater the spring pressure required to make it follow cam forms. This is why a pushrod-and-rocker valve train typically requires twice the spring force needed by an overhead-cam design. A change we have seen quite recently has been the adoption of very light F1-style pivoted finger followers as a substitute for the older “inverted bucket” piston-type tappets in overhead cam engines.

Next is the physical strength or fatigue tolerance of the connecting rods that join the pistons to the crankshaft. Con-rods can break at high revs, and pistons, subject to violent acceleration/deceleration cycles, develop fatigue cracks and come apart. Crankshafts that are well-behaved and long-lived at stock rpm may develop vibrational modes at higher revs that fatigue and break them. Cam drives, whether gear, chain, shaft, or toothed belt, can interact with the crankshaft to produce unstable herky-jerky twisting motions that can toss valves and twist the drive into scrap.

Special attention is often required here while developing racing engines. At Harley-Davidson in the ‘90s I was shown a box of what had once been experimental cam drives for the VR1000 Superbike. Undamped vibratory motions had destroyed the lot.

 

Frictional Losses and Parts Failures

Also of importance is the rapid rise of friction loss with higher rpm. Inertia loads on bearings (from the reciprocating parts) increase as the square of rpm, compelling designers to reduce the weight of pistons and con-rods as much as possible. This motivates the use of titanium instead of steel in rods, and the shrinkage of pistons from their 1950s resemblance to small buckets to the present ultralight “ashtray” look. Modern pistons are little more than a round disc to hold the piston rings, connecting via an under-the-dome box structure to a very short wrist pin, with a short pair of “skirts” to stabilize the piston against rocking in the cylinder bore.

High-duty pistons today tend to be forged rather than cast, and are carefully shaped in accordance with dynamic stress analysis to avoid stress concentrations that lead to cracking. This gives modern pistons their flowing organic shapes and freedom from sharp edges and sudden changes of cross-section.

Damage to or failure of the reciprocating parts—the piston, its rings and wristpin, plus the small end of the con-rod—result not from combustion loads but from the rapid acceleration and deceleration of these parts, which in ultra-high-rpm engines can reach 10,000G. Such accelerations are directly proportional to piston stroke and to the square of rpm. Since the path of development is often to increase rpm, the obvious line of attack is to shorten the stroke, then rev the resulting engine up to the stress limit of its parts. Two approaches have been used.

 

1. In its classic high-rpm four-stroke GP bikes of 1959-67, Honda kept the bore-to-stroke ratio close to 1.1 because larger pistons were much harder to cool. If, as an exercise, we begin with a 250 single and seek a shorter stroke through adopting more and smaller geometrically similar cylinders, we find that a 250 twin’s stroke is 79 percent of that of the single. If, like Honda, we move on to a 250 four, stroke becomes 63 percent of that of the single. For a six, the number drops to 55 percent. Only when we go to the extreme of building an eight-cylinder 250 do we arrive at 50 percent of the stroke of the original 68 x 68mm single. In 1967 there was speculation that Honda might follow up its 250 six-cylinder with a V-8, but the company withdrew from racing.

2. Formula 1 development has historically used cylinder multiplication (V-12s, a V-16, and an H-16) but more recently has adopted much larger cylinder bores and shorter strokes—going to the 2006 extreme of a 2.4-liter V-8 of 98 x 39.7mm dimensions, a bore/stroke ratio of nearly 2.5. In that year F1 engines supposedly reached 20,000 rpm.

 

As happens so often in life, going to extremes can create at least as many problems as it solves. In the early 1950s, BRM couldn’t afford to effectively develop its complex supercharged V-16. The same was true of Moto Guzzi and its legendary V-8 500. The greater the number of cylinders, the greater the heat loss from their much larger combustion-chamber surface area. More cylinders can also increase the friction loss from the greater number of parts. And think how hard it is to achieve a high compression ratio in a 98mm cylinder with a very short 39.7mm stroke: With a modern ratio of 13:1, a uniform combustion space between piston and head at TDC would be roughly 1/8 of an inch thick. That cramped space slows flame propagation—ignition must be timed to occur more than 60 degrees before top center in such engines—greatly increasing the time duration of heat loss.

The engineer’s choice of bore and stroke is also tied to valve area. There are limits to how fast flow can move through valves and ports, so when an rpm increase is desired, bigger valves may be needed—often bigger than will fit into the existing cylinder bore. This requires that bore be increased and stroke shortened to make room.

 

Bore and Stroke Ratios

Motorcycle engines have tended to avoid such extremes, mainly because their very limited tire footprints can’t handle the radical torque curves of F1 design (although some illustrious F1 organizations have tried their hand at designing engines for racebikes). A clear symptom of this is MotoGP’s limiting cylinder count to four and bore and stroke to 81 x 48.5mm (yielding a much more moderate bore/stroke ratio of 1.67). As motorcycle manufacturers are smaller than automakers, they simply cannot muster the $300,000,000 annual budgets of the larger F1 teams. Such limits make sense.

Ducati’s 1299 Panigale V-twin did reach 116 x 60.8mm bore and stroke, setting a benchmark for extreme bore/stroke ratio in a production machine: 1.91.

 

Valve Springs and Desmodromics

At various times in history valve springs have been the limiting factor in rpm, owing to quality issues and fatigue. Quality greatly increased with adoption of “cleaner” vacuum-remelted wire materials (that is, containing fewer crack-nucleation sites such as oxide inclusions) after 1957, and by shot-peening the wire to reduce surface cracking by placing the surface in compression.

Valve springs in production bikes are stressed to a lower percentage of the wire’s ultimate tensile strength than in race engines. As wire quality improved, it became possible to operate the springs at progressively higher stress levels. Even so, by 2004 MotoGP teams were having to change valve springs after each day’s free practices just to avoid failure. This point had been reached earlier in F1; first Renault and then the other manufacturers abandoned metal in favor of pneumatic springs in the mid-1980s. Ducati avoided this issue altogether by its long tradition of closing its valves not by springs but by separate closing cams and levers—the desmodromic system.

In containing the violent motions of internal parts at high rpm, engine structures flex. Honda, in trying to develop its four-stroke V-4 oval-piston NR500 GP bike, had to increase stiffness with extra metal. Inline-four engines with separate cylinder blocks can flex so much that they roll their base gaskets into little balls as parts chafe against each other. This led to the practice of making the upper crankcase in one piece with the cylinder block. After initial dyno testing of a new design, engineers eagerly await teardown to see if there is fretting, or marks of mutual rubbing and generation of wear particles, between major parts, indicating unacceptable levels of flexure in operation. Designs that are satisfactory at a product’s initial level of operation may not be after updates increase power and rpm.

Crankshafts and camshafts, because they are subject to sudden cyclically repeated loads, wind up and unwind in torsion: this is torsional vibration. In general, the longer the shaft, the more vulnerable it is to such motions, and the more intensive the measures adopted to suppress such motions must be. In F1, according to a Honda technical paper, 10 or more vibration dampers on crankshaft and cams may be necessary to achieve this.

As engineers have tackled all these problems, solutions have emerged that are able to combine affordability with the greater power that increased rpm can deliver. What was radical stuff a decade ago is normal production tech today.

 

 

 

 

 

 

 

 

 

 

[L0shMi]

https://www.motorsport.com/f1/news/how-f1s-development-battle-has-swung-between-mercedes-and-red-bull/6693153/

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