Of spoilers and speed holes

Dailies -

By

bladespoiler

In 1992, the Honda CBR900RR Fireblade forever changed motorcycling. In the decade preceding its launch, two-wheeled performance had already undergone something of a renaissance. The 1984 Kawasaki GPZ900R made an insane amount of power — 115bhp — allowing it to become the first stock motorcycle to ever exceed 150mph. In addition to the liter bike, another class of motorcycle was also created — the 600. They could go around corners. Bikes like the GPZ600R made about 75bhp. But, the two traits, performance and handling, weren’t able to totally coexist until Tadao Baba had the radical idea of putting a 122bhp engine into a bike the size of a 600. Thus the modern performance motorcycle was invented.


But, that big engine and compact frame had help from an unlikely source. Take a look at the sides of the front fairing and the lower leading edge of the side fairing on this ’92 bike. See them? Speed holes! The 2012 Honda CBR1000RR won’t claim such an epochal position in motorcycling lore, but it does make use of a similarly obscure aerodynamic aid. Chin spoiler!

Honda is staying fairly tight lipped about the function of the spoiler, saying only that it “reduces aerodynamic lift at speed, improving handling.” But, we can extrapolate some certainties from that statement.

The company was equally cagey about the ’92 Blade’s speed holes, only saying that they aided side-to-side transitions (ie turning) at high speeds. Motorcycle aerodynamics at the time were less infinitesimally understood and it’s likely that this was simply a styling nod to the concurrent GP bike. Other sources have suggested that the holes were there to reduce the visual bulk of the fairing by allowing light to travel through, an explanation that seems much more likely.

So does the ’12 bike’s chin spoiler serve an equal looks or marketing-only purpose? No so fast, Mr. Skeptical. There is precedent here. The Ducati GP10 employed winglets which, many speculated, where there to help keep the front end down on the incredibly powerful machine. It turns out that, instead of reducing a preponderance of wheelies, they actually acted like the Advanced Blended Winglets you see on many boeings, generating vortexes that helped draw cooling air through the fairing. It turns out that the CBR’s fairing has been designed to achieve something similar.

The new CBR’s fairing takes advantage of an inner fairing layer to help create a bubble of low pressure air around the outlets in the side fairing. This helps draw air through the radiator, assisting with cooling and helps reduce turbulence experienced by the rider.

Unlike a large wing or rear spoiler on cars like the Porsche 911 Turbo, the CBR’s new chin spoiler isn’t intended to have a massive effect on downforce, but rather limit high pressure air moving over the top of the front wheel from having a positive effect on lift. It carefully channels air away from a problem area. Think of the spoiler as a cure rather than a new appendage. The effect? There will likely be some immeasurable improvement to high-speed stability and steering accuracy as the front wheel remains in slightly better contact with the ground.

Like speed holes, the chin spoiler isn’t going to be a huge deal in the real world. But, has your bike got ‘em? Your friend’s is about to. It might not be a tangible performance benefit, but it is indicative of Honda’s approach to this new Blade. Unable or unwilling to totally replace the old model, they’ve instead refined this new bike to the nth degree.

  • John

    this principle’s been around forever I’m sure…it’s the “dimpled golfball” and “owl feather” effect. In my humble opinion, it’s the recent advance in airflow tech that now enables the engineers to actually “see” what the air does instead of just guessing, like with the simpsons style speed holes on the ’92, which I actually think did nothing but create drag instead.

    I think those new inner ridges may actually be very beneficial in directing airflow. A weird “negative” effect that helps in a positive way,,if that makes any sense.

    “The new CBR’s fairing takes advantage of an inner fairing layer to help create a bubble of low pressure air around the outlets in the side fairing”…actually these applications tend to reduce low pressure areas not create them. They may just be trying to reduce the low pressure created by the front wheels (if there is one).

    • John

      ps..winglets smooth out vortices..not create them

      • Andrew

        Yeah, those Boeing winglets actually lead to smaller vortices.

        I am a bit confused on your statements though, John. For starters, the Ducati winglets don’t create a high pressure zone behind them, where the radiator outlet is. By accelerating the air right before it moves past the radiator outlet they create a low pressure pocket per Bernoulli’s principle. I’m not sure where you’re getting the principle that high pressure air will suck out low pressure air.

        For a radiator you’re looking for the largest pressure differential possible, as the bigger the differential, the more air will want to move across that differential through the radiator. The inlet is naturally getting a high pressure boost as it has the bike’s speed of air ramming up against it. By dropping the pressure at the outlet you then have a nice gain in airflow due to the larger differential.

        • Andrew
          • John

            I don’t think we disagree on this andrew, but there’s nothing erroneous with what I wrote. Check my comments. I never said the winglets create a high pressure zone “behind them”. They channel the airflow through a given direction, and if there is an adequate enough gap in the duc’s side exhaust, then yes, it will create a nice pocket that facilitates the low pressure air to “meet up” with the high pressure air. “sucking it out” is a simple metaphor.

            You also DO NOT want the largest pressure differential possible, this will just lead to drag. the chin spoiler on the honda in this article is there BECaUSE the engineers must’ve seen a large enough air pressure differential in aero testing. The ridges “buffet” this air, causing slight turbulence behind the wheel, so on & so on. We don’t disagree so much, our terminology is slightly different.

            • Andrew

              Ah, understood, thanks for clearing that up! As for the pressure differential, I think we’re agreed again, just that they want to minimize pressure on as much of the front end as possible without limiting radiator flow.

              • John

                yep!..there’s obviously some compromise there since they won’t be getting meximum airflow into the radiator. But they gain that back by not having to use that extra bit of horsepower to propel the bike forward just to make up the difference. Better aero = Less power needed = less fuel = less wet weight! (theoretically,as they haven’t released figs yet)

    • FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

      Yo dawg, we heard you like fairings, so…

      • John

        funny meme reference is funny!

  • Glenngineer

    Honda is easily the top of the heap when it comes to aerodynamics. They’re latest crop of bikes have some of the best aeros in motorcycling. Makes me anxious for a new ST1300.

    • http://hellforleathermagazine.com Wes Siler

      On the Duc they create them, think of a stain vac sucking air through the fairing holes.

      • John

        they have the vac effect but in a different way. But they still don’t create a vortex. creating vortexes would create an adverse effect on the bike. too much drag to be worth the effort..they instead create a smoother airflow…in other words they channel the air in one direction. the winglets are located on the sides of the fairing, which probably means it’s not meant to direct air into the cooling chamber,,but suck air out of the side opening, sucking out the hot air faster,,thus in a way aiding in the cooling.

    • always_go_big

      They are also, on occasion, at the top of the heap for playing with themselves. Which on a larger scale leads to greatness like the Fireblade but on a smaller scale most often leads to great marketing BS.

      I still prefer to strip to my underwear and lie in a prone position atop the bike for best airflow and stability at speed.

  • Deep6Dive

    I had a ’95 CBR900RR Smoking Joes. The holes in the fairings were almost as awesome as the neon yellow purple and white stickers. Thank god for flat black spray paint.

    • http://hellforleathermagazine.com Wes Siler

      Yep, that’s what the article says, low pressure air sucks air through the fairing outlets.

      • John

        me thinks your comments section is broken,,you’re replying on everyone else’s posts..lol!

        but again,,it’s HIGH pressure that usually sucks air out of a low pressure zone..low pressure isn’t used to suck low pressure out…the inner-fairing ridges on this Honda scramble the high pressure air coming through,,reducing the low pressure zone,,it seems counterintuitive, but it helps the bike by having less to push against and not being sucked back by the low pressure void. On the ducati,,the winglets, direct HiGH pressure air over the side opening, thus sucking LOW pressure air out.

        actually just looked at it again,,I see what you mean on the side fairing thing…I thought you were referring to that part in front as the “inner fairing”..

        • http://hellforleathermagazine.com Wes Siler

          Yeah, on my phone and screwing things up. Thanks for the explanation.

  • http://www.postpixel.com.au mugget

    Huh – interesting about the wings on the Ducati MotoGP fairing, I had still thought it was for downforce or something…

    Refining the ‘Blade to the nth degree, not a bad thing when it’s such a good bike!

  • jason McCrash

    Didn’t it come with a 16 or 16.5 inch front wheel? Never understood why they left that on there after the first few years.

    • http://hellforleathermagazine.com Wes Siler

      16. It was supposed to make steering quicker, but just made shopping for tires a bitch. Thanks pirelli for making diablos in 16.

      • http://pics.zenerves.net/index.php?gallery=vehicules tropical ice cube

        Currently shopping for a front tyre on my “brand new” 1984 VF500F2 – you say Diablo?

        • http://hellforleathermagazine.com Wes Siler

          If they’re still making them in 16 inch, then they’re great tires.

          • jason McCrash

            http://www.americanmototire.com/catalog/index.php?manufacturers_id=650&osCsid=a64ba18042ae8b528010c5c2df66142b

            Not a lot listed there…….. I’m sure there is a 17″ swap out there. I found bolt on 17″s for my CB1000 “Big One” that came on 18′s. Changed the bike completely.

            • http://pics.zenerves.net/index.php?gallery=vehicules tropical ice cube

              Thanks guys. I was afraid of that 16′ front, but it works better than I though. Or will, for as long as I can find rubber for it. I plan to keep it as stock as possible, but it would greatly benefit from a modern fork, brakes and tyres, there is no denying that.

              • jason McCrash

                Do some quick research, I bet there is a rim that is a direct swap or a direct swap with different discs. I’ve done swaps on 4 or 5 bikes, from complete front and rear suspensions tho just fork parts or a rim and other than the bike no longer being ‘pure’ you would never know.
                Just swapped a ZRX1100 front end onto one of my 93 1100 Zephyrs 2 days ago. The other one has complete ZRX suspension at both ends. 99% bolt on. I was researching a swap for my 89 Hawk GT and believe I read that Honda used the same fork spacing on a lot of that era (late 80′s-early 90′s) bikes. Head bearings are the other thing, if they are the same size as your donor bike then it is a pretty basic job swapping.
                If I weren’t 6’3″ i would’ve snapped up a 900RR years ago.

          • http://www.lgdm.fr stempere

            They don’t, from the rosso to the supercorsa SP they only make them in 17 now.

  • dux

    Spoilers + Honda = Obvious why didn’t we do this before? Maybe the next model refresh will include ground effect LED lighting.

  • Sean Smith

    I’ve always wondered why more people don’t explore aerodynamic mods on their bikes. For the money, I’m not sure there’s any way to go faster.

    • Devin

      Because you can’t brag about how low your drag co-efficient is at the coffee shop like you can the numbers on a dyno.

  • http://krtong.com KR Tong

    I think you can do more with your body position than anything. I’ve learned my old unfaired CB will actually reach it’s top speed if I plank on it. It’s comfier too.

  • DoctorNine

    Jeebus. This is as bad as TV bass pros arguing about the hydrodynamics of a classic fishing lure.

  • Rick

    It’s a really bad sign when when you buy a new motorcycle only to miss the one which preceded it…Baba-san’s Whiffle Ball had me wishing for the ’91 ZX-7R almost from day one. This was a strange motorcycle, one I never fully trusted. Or felt comfortable on with its fat beach ball of a fuel tank splaying my knees so far apart!

  • http://www.faster-faster.com fasterfaster

    “vortices” <– yes, I'm that anal about sciencey terms.

    • John

      noticed that a while ago…I’m especially ashamed…good call…

      p.s. your design folks deserve giant pats on their backs…great work

      SCIENCE!

  • Tim

    My old Honda Blackbird manages to make respectable speeds despite a pretty average HP rating and a lot of weight. I have owned quite a few bikes over the years, but none that slip through the air as cleanly. It is clear that even back in the 90s when they designed it they did some serious wind tunnel work. The pointy nose opens the hole in the air, and the tail closes it.

  • Ben

    The CBR600 F3 front wheel is 17 and a direct swap over. Loads of ‘blade owners do that. Its also an easy swap to most CRFs for supermoto so unfortunately they are Ebay gold.

    I had a 93 blade (1st gen frame was steeper and stiffer) with a 97 motor in it (919cc), 1000rr forks and brakes with a VFR single sided swing arm on the back (easy swap). Later I street fightered the hell out of it.

    I was far and away the funnest bike I’ve ever owned. I rode it from Vancouver to La Paz down the pacific coast the whole time. She got stolen in Mexico. Sad day. If anyone has seen this bike since 2008, let me know some one loves her.

    http://farm5.static.flickr.com/4062/4270061382_3ed00cff7e_z.jpg?zz=1