Norton Commando Land Speed racer update

It's a little surprising how much difference small aerodynamic changes can make in an un-faired bike, particularly when you get up into the 150 mph range. I recall some advice from an old-timer with several speed records when I was first starting at El Mirage. He said making sure you had your toes pointed straight forward instead of hanging down to catch the air made a measureable difference in top speed. This was on a bike with a conventional riding position, and wouldn't be possible in one of the stretched out riding positions on highly modified bikes.

My biggest limitation was not being able to bend my neck enough (arthiritis) to get into a really good tuck and still see ahead. I was complaining to one of the other (much younger) racers, and he said he had improved his ability to tuck in well by doing regular stretching exercises on his neck. Unfortunately, that didn't seem to help me regain lost flexibility. Maybe I need some glasses with prisms to let me look down and see straight ahead. :lol:

The point of all this is that all the small things you are working on are worth the effort. At some point in looking for more speed, the improvements are going to only come in small increments, but those increments add up.

Ken

lcrken said:

It's a little surprising how much difference small aerodynamic changes can make in an un-faired bike, particularly when you get up into the 150 mph range. I recall some advice from an old-timer with several speed records when I was first starting at El Mirage. He said making sure you had your toes pointed straight forward instead of hanging down to catch the air made a measureable difference in top speed. This was on a bike with a conventional riding position, and wouldn't be possible in one of the stretched out riding positions on highly modified bikes.

My biggest limitation was not being able to bend my neck enough (arthiritis) to get into a really good tuck and still see ahead. I was complaining to one of the other (much younger) racers, and he said he had improved his ability to tuck in well by doing regular stretching exercises on his neck. Unfortunately, that didn't seem to help me regain lost flexibility. Maybe I need some glasses with prisms to let me look down and see straight ahead. :lol:

The point of all this is that all the small things you are working on are worth the effort. At some point in looking for more speed, the improvements are going to only come in small increments, but those increments add up.

Ken

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We gained and additional 2.5mph between the 1 and the 1.5 by just pointing my toes straight back rather than leave them on the footpegs as I had been doing in previous runs!

I was not going to wait around for someone else to post this.

A 6 speed close ratio box might not do much more for you than a 4 speed close ratio box. The difference with the 4 speed box is the lurch as you start to move, but once you are mobile and the motor is revving hard that becomes irrelevant It depends on how long the run up to the speed trap is. A close set of 4 speed gears can be had for about $600.

Don't be foolish. Go with a six speed for your land speed record endeavors. PM me as I just removed a TTI six speed from my long stroke Norton Seeley and may part with it.


From the TT Industries web site.


6 Speed Heavy Duty Gearbox

Gear Ratios offered :
1st 2nd 3rd 4th 5th 6th
Low Ratio
2.44 : 1 1.755 : 1 1.418 : 1 1.243 : 1 1.1 : 1 1 : 1
Standard Ratio
2.294 : 1 1.755 : 1 1.418 : 1 1.243 : 1 1.1 : 1 1 : 1
Close Ratio
2.167 : 1 1.69 : 1 1.418 : 1 1.243 : 1 1.1 : 1 1 : 1
2.09 : 1 1.69 : 1 1.418 : 1 1.243 : 1 1.1 : 1 1 : 1

http://www.ttindustries.com/6_speed_gearbox.html

versus

4 Speed Heavy Duty Gearbox

Gear Ratios offered :
1st 2nd 3rd 4th
Low Ratio
2.178 : 1 1.46 : 1 1.176 : 1 1 : 1
Standard Ratio
1.96 : 1 1.46 : 1 1.176 : 1 1 : 1
Close Ratio
1.89 : 1 1.4 : 1 1.13 : 1 1 : 1
Moto Cross Ratio
1.89 : 1 1.52 : 1 1.237 : 1 1 : 1

http://www.ttindustries.com/4_speed_gearbox_hd.html

My experience is that the most important thing is to have a close ratio in the top two gears. Top gear is always 1:1, and you really need the next one to be very close, like 1.1:1. If you have a really narrow power band, it's also important to have the next gear down be pretty close. First gear, or first and second in a 5-speed, aren't very critical. A lower first gear is nice for the start, but not essential. I've been running a close ratio Quaife 5-speed in my bike, and as long as I've got the right overall gearing, it has no problems staying in the power band during shifts.

I don't have any experience with a 6-speed in a landspeed bike, but it certainly seems like a good idea, at least in terms of how quickly you can get up to speed. At Bonneville, the course is long enough that taking more time to get up to speed isn't a problem, but at shorter courses it could be.

And if you have a really narrow power band that drops off sharply enough at high rpm (think 2-strokes) that you can't just rev higher before shifting, then a 6-speed could be essential

Ken

What I find interesting is the difference in the torque and power verses revs curves in some motors. Sometimes they simply rise together to a peak, but often the torque curve peaks while the power curve continues to rise. In one of the Youtube videos, the claim is made that fastest acceleration is achieved by changing up at max. horsepower. My feeling is that it is a waste of time changing up after you reach max. torque. The biggest thing I've noticed about the heavy commando crank is that if you have a high gear and expect it to spin up using the throttle, it takes forever. However if you keep it spinning high, and race-change using a close box, it is very fast. When you are doing a speed record on the salt, surely it is important to keep the crank spinning high so you use it's inertia to advantage ? What I can't figure out, is will the revs rise above maximum torque to where maximum horsepower occurs when wind resistance has to be overcome. With my own bike, it is always about acceleration on short circuits, so I never get up to the sorts of speeds you encounter in a land speed record attempt.

Eldo – you and Herb’s efforts are impressive as are the results. Nothing new to report here, but was diddling the numbers you threw out earlier and put together a couple plots of your speed vs rpm information. Seems like you’re right there knocking on the record’s door. A few hundred more rpm, a little more gear, some aero improvements, and a sturdy little 120 lb flat track rider and you’d be there. I guess that last item might take all the fun out of it for you. But I mention it because your 1 mi speeds are records, and I imagine your equipment would be operating in a very different regime with a little person on it (it would unquestionably increase the 1 mi speed). Keep grinding away and you’ll likely get there.

acotrel said:

What I find interesting is the difference in the torque and power verses revs curves in some motors. Sometimes they simply rise together to a peak, but often the torque curve peaks while the power curve continues to rise. In one of the Youtube videos, the claim is made that fastest acceleration is achieved by changing up at max. horsepower. My feeling is that it is a waste of time changing up after you reach max. torque. The biggest thing I've noticed about the heavy commando crank is that if you have a high gear and expect it to spin up using the throttle, it takes forever. However if you keep it spinning high, and race-change using a close box, it is very fast. When you are doing a speed record on the salt, surely it is important to keep the crank spinning high so you use it's inertia to advantage ? What I can't figure out, is will the revs rise above maximum torque to where maximum horsepower occurs when wind resistance has to be overcome. With my own bike, it is always about acceleration on short circuits, so I never get up to the sorts of speeds you encounter in a land speed record attempt.

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This is something we found interesting as well. I have always tried to run up to the peak of the hp curve in my runs. At Loring, however, the engine would not climb that high, and seemed to hold at 7200 rpm, which just about splits the torque and hp peaks. In the future, I may try to shift at the torque peak rather than the hp peak, and I will definitely by "speedshifting" as well, without the clutch or even much of a decrease in throttle. We'll see what happens.

Those are great graphs, WZ507! Thanks! It certainly is exciting to think what we could get to with a longer run (like the short course at Bonneville!)

I hear it all the time that I'm too big for this sort of thing, and that I should get a smaller rider, but at the risk of sounding selfish, I have absolutely no interest in what somebody else could do on this bike. Riding this bike is something I find immensely enjoyable. I also feel that when we eventually make it to Bonneville, my weight will not be such an issue, and I do plan on trying to run to the Partially Streamlined rules with an Airtech fairing in the future, which should help "level the playing field" so to speak, in terms of my physical size. We'll keep chipping away, and see where we end up.

Eldo, by all means experiment a bit. What you will find is that in order to attain peak acceleration and ultimately peak speed, you should be shifting up to the next higher gear while in the higher rpm range of the torque curve peak. Fortunately with a Commando, even in a very aggressive state of tune or short stroke, the engine has a relatively broad torque range.

Think of your gear box as a torque multiplier (it is). When shifting up you are reducing the mechanical "advantage" of converting torque to your rear wheel. Now visualize (or look at) the torque curve and think about what happens when you shift up a gear on the lower rpm side of peak torque, your rpm drops and your torque available from the engine decreases while you just reduced the mechanical advantage between the engine and rear wheel (ie less mechanical advantage to convert torque to the rear wheel). In contrast, if you up shift at an rpm higher than peak torque, if your jumps between gears are not too great, your engine rpm will drop as expected but your engine is now putting out more torque than before the up shift to overcome the mechanical advantage you lost while shifting up.

Up shifting at peak HP may make sense as the bike approaches (peak) terminal velocity but at lower speeds the torque is what accelerates you so your shifting would want to keep the engine in a range that maximizes torque. It's an interesting dynamic system of rpm, torque, power, rolling resistance, bike velocity and air drag

I would think the sweet spot for your bike and gearing would be going through the traps WOT at peak HP with no acceleration.

As for weighing in on body mass and body girth versus wanting to remain the pilot.............have you considered a supercharger? In all seriousness, there's a lot to be gained with body position; consider reworking the controls to allow better body position; The body can also act as a bit of a fairing. The challenge is collecting the data on results. To that point, I did a quick search and see that the University of Waterloo has a wind tunnel and I believe it is in your neck of the woods. I doubt it's big enough for a full size test (2' X 2' X 8') so a model would be required. There is mention that the University has access to a local larger facility so you might be able to get data from full scale testing.

http://www.fmrl.uwaterloo.ca/facilities.html

If you don't have any connections there maybe approach the appropriate faculty and see if you could work an arrangement with them through a graduate student to get some wind tunnel time; maybe support/justify a grad students research project (become the project).

As for Bonneville and streamlining, it is a big commitment so do your homework (read) and consult others in the know. Ken (lcrken) is an excellent resource as he has been there and done that.

What gear box are you running?

Dances with Shrapnel said:

As for weighing in on body mass and body girth versus wanting to remain the pilot.............have you considered a supercharger? In all seriousness, there's a lot to be gained with body position; consider reworking the controls to allow better body position; The body can also act as a bit of a fairing. The challenge is collecting the data on results. To that point, I did a quick search and see that the University of Waterloo has a wind tunnel and I believe it is in your neck of the woods. If you don't have any connections there maybe approach the appropriate faculty and see if you could work an arrangement with them through a graduate student to get some wind tunnel time; maybe support/justify a grad students research project (become the project).

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Eldo said:

Fast Eddie said:

Aerodynamics makes an exponentially bigger difference the faster you go.

Altering small things on the bike to allow you to tuck in better, and, as daft as it sounds, practicing tucking in as tight as you can, could well yield several MPH.

Unless you're experienced at racing or similar, most of us aren't nearly as tucked in as we think we are, so it's definitely something to practice, and get someone to take side on and frontal photos so you can see where you might be able to reduce that frontal mass a little here and there.

When's your next outing? Your results are awesome and I can't wait for the next round!

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Yeah, we live in Waterloo, Ontario, and the University of Waterloo has a great engineering and physics faculty. Also, we are becoming a real "high tech" hub, and there are lots of "start-ups" being fostered, many in conjunction with the University of Waterloo. One such "start-up" company is working with the U of W Fluid Dynamics laboratory, and is developing a computer generated "Virtual" wind tunnel, so I have been in touch and we'll try to get some aerodynamic positioning info over the next few months. I'm looking forward to seeing where I can make some gains.
I also contacted the real, actual U of W wind tunnel facility, but they suggested I have a budget of $10,000 to START the session, so that is just not financially realistic for me.

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I would not give up on it. When you consider what it costs to build, maintain, transport, lodging, registration, meals etc......

Lots of other resources in the region and I would recommend getting with the faculty and see if there is the possibility of an alliance with a grad student.

CFD is may be a way to go and they may already have a generalized model of a bike and a rider that they can manipulate. To make a specific model would take time and money.

I suspect the best bang for your buck would be to read up on the work of others as you are not the first to go down this path and as someone else has mentioned, have someone photograph your tuck to see where you are. Unfortunately/fortunately frontal area is not the whole game and it is probably not intuitive, thus my remarks that the body can also provide streamlining for the whole rider/bike system.

I don't think your body mass has much to do with the top speed you achieve as long as the run up to the speed trap is long enough. All it does is add inertia. The killer is wind resistance. If your leathers are loose, that might make a difference. I would not try to chase the record by changing the rider, you are obviously having a lot of fun. And that is what motorcycling is all about.

With the gearbox, all you probably need are the top 3 gears close ratio. You should be able to pick up a close ratio 4 speed cluster fairly cheaply and if 1st gear is too high, fit the 1st gear out of your standard Commando box.

acotrel said:

I don't think your body mass has much to do with the top speed you achieve as long as the run up to the speed trap is long enough. All it does is add inertia. The killer is wind resistance. If your leathers are loose, that might make a difference. I would not try to chase the record by changing the rider, you are obviously having a lot of fun. And that is what motorcycling is all about.

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Body mass, only in it contributes directly to rolling resistance but my choice of the word body mass was poor as I was meaning to convey big as in massive, not mass. Yes, wind resistance is the biggest factor

Are you saying that body mass increases rolling resistance because it deforms the tyres more ? In a land speed record, does the weight of the bike affect it's top speed, if the run-up is long enough ? Surely once it is rolling, the only thing which stops it is wind resistance and the effect of the wheel on the salt ? Perhaps higher tyre pressures might give higher speed ?

acotrel said:

Are you saying that body mass increases rolling resistance because it deforms the tyres more ?

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Yes

acotrel said:

In a land speed record, does the weight of the bike affect it's top speed, if the run-up is long enough ?

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Yes

acotrel said:

Surely once it is rolling, the only thing which stops it is wind resistance and the effect of the wheel on the salt ? Perhaps higher tyre pressures might give higher speed ?

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Yes, exactly, "and the effect of the wheel on the salt" ie rolling resistance; you've just answered your own question. And please stop calling me Shirley.

Eldo said:

We made the gas tank out of fiberglass from Dunstall molds, and it is made in 2 parts, the top and the floor. I "sectioned" the top 2" before we glued the floor in, so the tank is actually 2" shorter already. , and the seat is extended 5" so I could get my butt way back and lay down with my head right down on the tank.

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andy, i gave up on stock-style tanks on my T120, and still am within the rules at loring. this is what i ran at ECTA, and it was slow. i had to sit there with my chin on the tank, and the helmet stuck up like a pumpkin in the wind:



i ditched the tank, and run these instead:



the difference is that now my chest rests firmly on the top frame tube of this machine. i have the bruises to prove it. in addition, my face shield used to sit up on top of the tank, but now i can tuck my face down to the left, and look through the triple clamps at the track:



my left eye looks at the track, to the left of the fork tube. my right eye can still see the tach.

my face shield is full of divots from the left top triple clamp bouncing against it at 100+, but it gets my face down out of the wind.

I love the single minded focus you LSR guys have, I'm envious!

That "nothing else matters" feeling is probably what I miss most about racing, although, I did kinda struggle to keep on the healthy side of obsession!

If you haven't already, get a copy of a book called "Johnathon Livingstone Seagull" it won't help you improve, but I think you'll relate to and enjoy it... and it will kinda justify the obsessive behaviour a bit...!

I have long believed that to be successful in road racing, you must be compulsive obsessive. However it is a magnificent obsession, it makes you feel alive. The problem is that as we get older, were have to maintain the urge and it does not get any easier. For myself, financial constraints are defeating me. So I have to choose between and 'old farts' meeting' and 'historic racing'. If I go to the 'old farts', the competition won't be there, but it would be cheaper. What is more important - proving my bike is good by burning the arses of the historic guys or simply riding around enjoying myself ?