Denis Manning Tells All

I had a chance to talk with Denis Manning (the designer and owner of the worlds fastest motorcycle), at the Chicago Motorcycle Show. I have to suppose that after all the questions and autographs and nearing the end of the show that he was a very tired puppy. So I knew that I would have to either surprise or challenge him with my questions to have any chance of getting some quality time picking his brain. I told him that we would be attending his event in August with the Enfield effort and were also designing a streamliner for continued immersion in the max speed world. He turned out to be a wellspring and laid out his ideas on what it takes to make serious speed at Bonneville. I should've had a tape recorder but most of what he told me will be burned in my memory forever. He had on display his various speed record motorcycles spanning a couple of decades and walked me along each one and described what was good and bad about them. He quoted me dimensions, gear ratios and suspension settings and talked about his theories and some of the great people he has been involved with. It was one of the greatest conversations that I have ever had with anyone!...  Here are the basic rules to going fast at Bonneville: The challenge is 90% Aero drag vs available traction and 10% rolling resistance. Yes, weight is an issue and he told me that they had just completed lightening their package by 100 lbs.! They are still crunching numbers and refining the package with the knowledge they have gained. They were heading to the N2WT wind tunnel from the show to refine the heat control ingress and egress and to optimize the ride attitude.  For comparison sake, a turbocharged Suzuki Hayabusa putting out maybe 550 HP and running close to stock wheelbase and fairing, tops out at a VERY SCARY 256 MPH. It must also add about 75 to 100 lbs. to help control wheelspin at speed. That would bring their total package up over 900 lbs. with rider on board. He spelled out some details of their record setting #7 streamliner... 1540 lbs. with Chris Carr on board. A for real carbon fiber monoque "tube" chassis with steel bulkheads ahead of and behind the rider. The suspension is a very conventional fork and swingarm set-up with about two total inches of travel. Their custom built engine (3 liters FIM Maximum) has a "big bang" (a la Moto GP practice) firing order that enhances traction by having longer duration between power pulses. The shape of the body is a close facsimile to a Koho Salmon (zero to 50 in 40 feet!) and was NOT developed in a wind tunnel. Their record run only took like 400 HP to go over 350 MPH and had 10% slippage (traction loss). The engine, by the way, has potential for 780 HP! The final gearing was not overdriven but net out to 1.82:1...WOW! That's nearly 2 to 1 folks! This rascal was pulling very hard up to speed! The afore mentioned Hayabusa Making some 150 HP more, struggles to reach a top speed that is 100 mph slower...Hmmm. It's that darned aero thing that is limiting it's potential. They have to add a bunch weight to keep the rear wheel from spinning because their shape has way too much drag to overcome. Staying "ahead of the tire slip" as they say, is the adjustment that they (streamliners) make after each run. Primarily just a gearing change, should net a higher speed with enough traction. Let those numbers roll around in your head for a little bit and you start to see the real picture of what a great device they have created! They have plenty of power in reserve if needed, so the potential is only limited to (drum roll here) "available traction vs drag". Simplicity is bliss...uh...Yes but it's WAY more complicated than that!...Read on! According to their rider, Chris Carr, he said that the telemetry showwed that he was still accelerating out the back of the measured mile. So now do you see where rolling resistance comes into play? By lightening their overall package they should be able to get their acceleration completed sooner before the measured mile and arrive at a greater "measuerd" top speed. This sounds really strange that 5 miles of run-up isn't enough to get the job done...He was managing the wheel spin all the way to 350!!! Yee Haw!! Back to the vehicle info... They have placed transducers on the suspension to monitor the ride height (critical to running attitude or angle of attack). The engine and wheel speeds are monitored by a custom Motec data logging computer and is displayed to the rider in real time so he can see if he is in the record range. The transmission that they have developed is electronic sequential shift and is set up to keep gear change shock loads from breaking traction (interrupt the ignition, retard the timing, shift and resume in 6 tenths of-a-second!). Neat-O!   He also pointed out the $5000 windshield that doesn't distort the horizon so the rider can react to lean and yaw instinctively. Even more Neat-O!. Yaw is super critical! You just cant run these things in a drift due to too much crosswind or wheel overspeed. In a significant cross wind, the pressure differential from side to side, froces steering input that ultimately makes the streamliner run at an angle to the ground. When traction is lost, the yaw rate is left unchecked and as the rider countersteers to correct, the sudden change in load sets up a violent return that flips it over on the opposite side from the drift and AWAY YOU GO! Tumbling along the salt is definitely NOT COOL!... The average number of attempts in succession to set a "high" speed record at Bonneville is FOUR! These guys did it on their first official try!!! The challenge is immense! (Large gulp here!) You simply have to have ALL the factors going in your favor or you'll just go home disapointed. So let's bring it on!    Always racing, Phil