Do Aerodynamics Matter on 250/300 Ninja Racebikes?

[csmith12]

You race MotoSeries Timm? Cool, I will be seeing you next season for a couple races at least. I am pretty sure Todd will not say anything about the rinofender lol.

[tgold]

Yeah, Motoseries is the most local for me and I'm pretty much done chasing championships in a series like WERA. I was all on board with doing a full blown 250 superbike to compete with the 300s, but I think the most I'll do now is the aero stuff and use the Supersport Tuning Secrets of the Stars. It'll be a challenge to resist hitting the little bike with a lightness stick though.

[greenaero]

Sorry about the delay in jumping into this discussion, I've been traveling a lot lately. Improved aerodynamics provide benefits at all speeds but as others have noted, the benefit increases by the cube as speed increases. However I can say that even at typical street traffic speeds reduced air dag makes a significant difference ( at least in fuel economy) . That same imporvement in efficiency should convert to increased speed and acceleration on the racetrack. I would suggest checking your rulebook for what is allowed and make changes accordingly. If allowed longer wingdscreens, longer side panels, enclosed wheels , and an aero tail wouls all be effective. Look at the streamlined GP roadracing motos( 1940's I think ) before they were banned by the FIM. The banning was alleged for safety reasons ( side wind sensitivity) but more likely it was due to pressure from the other moto manufacturers who were getting their butts kicked by the streamliners.

[Motofool]

Originally Posted by tgold

......... When you want to win, you look at details because they make a difference. Aerodynamic details absolutely can make a difference.

This clever design converts part of the aerodynamic drag created when traveling at 180 mph (take-off) or 560 mph (cruising) into a lifting force of over 660,000 lb (300 tons):

Link to original page on YouTube.

[csmith12]

^^^^ yep

Check the pic below; novice pace (45ish mph), yet a very clear defining line where the air IS moving and NOT moving. What is funny is, the concave shape of the vortex is the same size and shape as the r6 fairing. It literally sweeps the air away and down away from the leg.

[tgold]

I remember reading an article about Erik Buell back in the day. He realized that air expands as it passes through the radiator, so on one of his bikes he carefully routed the ducting to and from the radiator in such a way that the net effect was that it actually produced a small amount of thrust. How's that for attention to detail?

[choneofakind]

Originally Posted by tgold

He realized that air expands as it passes through the radiator, so on one of his bikes he carefully routed the ducting to and from the radiator in such a way that the net effect was that it actually produced a small amount of thrust.

I'd be interested in seeing the article and explanation if you find it. A quick google search doesn't net me much.

[tgold]

Originally Posted by choneofakind

I'd be interested in seeing the article and explanation if you find it. A quick google search doesn't net me much.

I doubt if it ever made it to digital format. We're talking 25 or 30 years ago.

[allanoue]

Originally Posted by tgold

I doubt if it ever made it to digital format. We're talking 25 or 30 years ago.

Smacks of a free energy machine :-/

[choneofakind]

Huh. I have some doubts about the effectiveness since that's a case where modern CFD would be very helpful for taking everything into account with heat transfer, property changes, boundary layer changes, etc.

It's an awesome thought and shows how attentive he is to small things! I'd gander that it's a case of 6 one way or half a dozen the other, kinda like the awesome inverted single brake rotor vs typical dual standard rotors. Know what I mean?

[choneofakind]

Originally Posted by allanoue

Smacks of a free energy machine :-/

Nah, airflow and pressure changes do cool things.

For example, an Aero bicycle wheel with toroidal cross section has the ability to produce negative drag under certain angles of attack with the headwind. That's right, negative drag. aka, thrust. It's a thing.

I'd believe it, but I'd want to see it first and have it explained to me.

[tgold]

Originally Posted by choneofakind

I'd be interested in seeing the article and explanation if you find it. A quick google search doesn't net me much.

Page 208 and 209 of this link (you may have to google Kevin Cameron Buell Barton):

https://books.google.com/books?id=1r...Barton&f=false

The wording is slightly ambiguous as to whether Eriks design actually produced thrust, but give me a break... I was recalling from reading the original article in Cycle Magazine back in 1985.

[jkv45]

OK, I know we don't agree, but I feel most people are overstating the effects of aerodynamics on a Ninja 250/300 - at least in a sprint racing situation.

On a high speed track it's absolutely a factor. Anytime you are at WOT, and high speed, aerodynamics will make a difference. Land Speed Racing is where it's most important - you are at WOT and high speed most of the time.

To make a difference the aerodynamic improvements need to be significant. The Rynofender is significant. Removing mirrors and turn signals is significant. Adding a windscreen is significant. Sirref saw a substantial improvement in speed, and reduction in laptime, from adding a windscreen on a high speed track. Details do make a difference in racing, but if you are not running at the front you have bigger fish to fry.

Anytime you are cornering, braking, or not at WOT (maximum power), aerodynamic drag is not slowing you down. What percentage of time is that on a sprint track? To have a significant effect, you need to be at WOT and high speed - what percentage of time is that? Superior aerodynamics are only a substitute for superior power a small percentage of the time.

We don't really have any context for the question/answers. Are we talking about completely changing the shape of the cycle to improve aerodynamics or rounding some edges of the stock fairings?

I'm just saying don't expect to see any drop in laptimes from rounding some edges and reducing some gaps if you are road racing a Ninja 250/300.

Go ahead - let me have it...

[tgold]

Originally Posted by jkv45

OK, I know we don't agree, but I feel most people are overstating the effects of aerodynamics on a Ninja 250/300 - at least in a sprint racing situation.

On a high speed track it's absolutely a factor. Anytime you are at WOT, and high speed, aerodynamics will make a difference. Land Speed Racing is where it's most important - you are at WOT and high speed most of the time.

To make a difference the aerodynamic improvements need to be significant. The Rynofender is significant. Removing mirrors and turn signals is significant. Adding a windscreen is significant. Sirref saw a substantial improvement in speed, and reduction in laptime, from adding a windscreen on a high speed track. Details do make a difference in racing, but if you are not running at the front you have bigger fish to fry.

Anytime you are cornering, braking, or not at WOT (maximum power), aerodynamic drag is not slowing you down. What percentage of time is that on a sprint track? To have a significant effect, you need to be at WOT and high speed - what percentage of time is that? Superior aerodynamics are only a substitute for superior power a small percentage of the time.

We don't really have any context for the question/answers. Are we talking about completely changing the shape of the cycle to improve aerodynamics or rounding some edges of the stock fairings?

I'm just saying don't expect to see any drop in laptimes from rounding some edges and reducing some gaps if you are road racing a Ninja 250/300.

Go ahead - let me have it...

It all has to do with your frame of reference in what "significant" really is. Tenths and hundredths of a second do make a difference. Your assumption that only WOT matters is incorrect. Any time that you are on the throttle and it takes less power to move your bike, you will accelerate faster. That is an advantage. When I say reducing gaps, I don't just mean the gaps between panels, I also mean the gaps between the rider and the trailing edge of the fairing when you look at it from the side. Reducing gaps and smoothing edges costs very little, and (provided you don't crash) requires little in the way of maintenance, but every whack with a horsepower stick costs a lot more in terms of money and accelerated engine wear. Not to mention that the class I'm looking at racing in, you can do ZERO to the inside of the engine as far as modifications, but bodywork rules are pretty open. Why not go for an advantage if it's available?

One of the greatest obstacles that I have to overcome in my job every day is the perception by some that the way things are done now can't be "significantly" improved. The good part is that I have found time and again that there are little things that others say are insignificant and when they are improved, they make a huge difference because of the cumulative effect.

Let's say that my aerodynamic improvements have a (not inconceivable) net effect of .05 seconds per lap. A ten lap sprint race would mean a half second advantage over the entire race. At my home track, it's easy to have an average speed of 80 mph which equates to 117 feet per second. Divide that in half and at the end of a race, you get a 58 foot advantage over your result you would get if you had done nothing as far as improvements. The last race I was in, there were 4 tenths of a second covering first through third place. I was in first place. I was also the only one taking my hand off the clutch side bar on the straights. I'm not about to attribute that win to a simple aerodynamic advantage, but it made the job easier. Beside that, it's fun racing at 100 mph with one hand on the bars

[quarterliter]

Another thing to keep in mind is the fact that fairings have mass. Are aerodynamics worth the weight penalty of bodywork is another good question.

According to ninja250.org the fairings on the pregen weigh about 11 lbs. Depending on the track, I would imagine the 11 pound weight savings would be preferred over a higher potential top speed. Because those 11 pound savings will help in braking, cornering, acceleration...etc.
http://faq.ninja250.org/wiki/Reducin...n_a_track_bike

I am aware that race plastics are lighter, but in the case of a budget track bike, stripping the fairings off could make you go faster on the right track.
(complete sharkskinz bodywork for 250 is over $1000)

[tgold]

Originally Posted by quarterliter

Another thing to keep in mind is the fact that fairings have mass. Are aerodynamics worth the weight penalty of bodywork is another good question.

According to ninja250.org the fairings on the pregen weigh about 11 lbs. Depending on the track, I would imagine the 11 pound weight savings would be preferred over a higher potential top speed. Because those 11 pound savings will help in braking, cornering, acceleration...etc.
http://faq.ninja250.org/wiki/Reducin...n_a_track_bike

I am aware that race plastics are lighter, but in the case of a budget track bike, stripping the fairings off could make you go faster on the right track.
(complete sharkskinz bodywork for 250 is over $1000)

By all means, go ahead and ride naked if you like, and yes, the wrong fairing can make you go slower, but there are relatively easy ways to test your theory.

BTW, I rarely buy new bodywork. I buy a bike with bodywork already on it or I buy it used.

I stopped going to Cheesecake Factory about a year ago. The 35 pounds I lost will more than offset the 6 or 7 pounds of race glass on the bike

What I plan to do with the aeros on the 250 Ninja may fail. I don't know for sure. The only way to know for sure what the result will be is if I do nothing.

[Panda]

Originally Posted by choneofakind

I'd be interested in seeing the article and explanation if you find it. A quick google search doesn't net me much.

The WW2 era P-51 generated some thrust from the radiator via the meredith effect. Try googling that.

Tbh I'd be surprised you'd see any kind of net positive thrust or any meaningful thrust offset at the low speeds a bike travels.

[jkv45]

Originally Posted by tgold

It all has to do with your frame of reference in what "significant" really is. Tenths and hundredths of a second do make a difference. Your assumption that only WOT matters is incorrect. Any time that you are on the throttle and it takes less power to move your bike, you will accelerate faster. That is an advantage. When I say reducing gaps, I don't just mean the gaps between panels, I also mean the gaps between the rider and the trailing edge of the fairing when you look at it from the side. Reducing gaps and smoothing edges costs very little, and (provided you don't crash) requires little in the way of maintenance, but every whack with a horsepower stick costs a lot more in terms of money and accelerated engine wear. Not to mention that the class I'm looking at racing in, you can do ZERO to the inside of the engine as far as modifications, but bodywork rules are pretty open. Why not go for an advantage if it's available?

One of the greatest obstacles that I have to overcome in my job every day is the perception by some that the way things are done now can't be "significantly" improved. The good part is that I have found time and again that there are little things that others say are insignificant and when they are improved, they make a huge difference because of the cumulative effect.

Let's say that my aerodynamic improvements have a (not inconceivable) net effect of .05 seconds per lap. A ten lap sprint race would mean a half second advantage over the entire race. At my home track, it's easy to have an average speed of 80 mph which equates to 117 feet per second. Divide that in half and at the end of a race, you get a 58 foot advantage over your result you would get if you had done nothing as far as improvements. The last race I was in, there were 4 tenths of a second covering first through third place. I was in first place. I was also the only one taking my hand off the clutch side bar on the straights. I'm not about to attribute that win to a simple aerodynamic advantage, but it made the job easier. Beside that, it's fun racing at 100 mph with one hand on the bars

Let me put it another way - look for "significant" improvements elsewhere first. Tenths and hundredths don't make much of a difference if you are 1 second behind - are you battling for the win each time out?

There are certainly areas inside the engine that "blueprinting" is allowed, and there are, according to some people here, large tolerances in engine production of the Ninja. Just doing a valve job (is that allowed?) will most likely yield improvement. Increasing usable power will give you improvements anytime you are at WOT.

Do you have ceramic bearings? Do you have numerous engines, some better suited for faster tracks and others better suited for slower tracks? Have you dyno tested them? Are you changing tires often? There are a ton of things that can be done to lower laptimes. Are you willing to drop another 10 pounds to go .05 seconds faster? Details.

As far as aerodynamics helping acceleration if you are not at WOT - just open the throttle more if you want more acceleration! You are setting the speed - and choosing less than the maximum available - it's not being held back by power or aerodynamics.

Look at weight reduction. That provides improvements a large part of the time (unlike aerodynamics). Reduced weight shows benefits in accelerating and braking, and the percentage of time you are doing either is substantial.

You haven't outlined your ideas on the major aero improvements you are considering. Maybe they will give you the .05 second improvement you want.

[Panda]

All I've learned from this thread is to keep my mouth closed when I'm trying to ride fast.

[csmith12]

Originally Posted by Panda

All I've learned from this thread is to keep my mouth closed when I'm trying to ride fast.

bwahahahahahhahaha

[Motofool]

Originally Posted by csmith12

^^^^ yep

Check the pic below; novice pace (45ish mph), yet a very clear defining line where the air IS moving and NOT moving. What is funny is, the concave shape of the vortex is the same size and shape as the r6 fairing. It literally sweeps the air away and down away from the leg.

Very interesting pic !!!
Many people don't know that, unlike liquids, hot air is much more viscous than cold air; hence, it produces more friction.

Originally Posted by Panda

The WW2 era P-51 generated some thrust from the radiator via the meredith effect........

Another thing that made the P-51 a racing machine was the shape of the airfoil of the wings.
That shape was developed to induce laminar flow (to avoid turbulence over the surfaces).

Please see:
https://en.wikipedia.org/wiki/North_...nd_development

The H-1 Racer, designed and built by Howard Hughes, is another example of attention to details that made a huge difference and became standard practice in the aviation industry.
Copied from
https://en.wikipedia.org/wiki/Hughes_H-1_Racer
"Streamlining was a paramount design criterion resulting in "one of the cleanest and most elegant aircraft designs ever built."
Many groundbreaking technologies were developed during the construction process, including individually machined flush rivets that left the aluminium skin of the aircraft completely smooth.
The H-1 also had retractable landing gear to further increase the speed of the aircraft, including a fully retractable hydraulically actuated tail skid."

Turbulence is bad because it consumes lots of energy: imagine many microscopic tornadoes, the energy to make those spin fast and change direction comes from your engine/fuel.

When the pressure of the explosions inside the combustion chamber is maximum, your engine is doing all it can to transform the thermal energy of the fuel into torque delivered to the rear wheel.
That torque is used to overcome inertia of bike+rider and/or friction from air and road, depending if accelerating or not.
Anything done to reduce both: mass (inertia) and friction, will be traduced in higher acceleration and maximum speed.

Hollow bolts have been very much used in racing: a few ounces here and there has made a difference for acceleration.
Saving weight without sacrificing strength has been the reason behind the introduction of expensive parts made of titanium and carbon fiber.

Many times @csmith12 has mentioned here the importance of keeping momentum while racing a 250.
That means that, as much as possible, you avoid slowing down (energy produced by your engine first and then wasted as heat via pads and discs) to recover that speed again (more energy produced by your engine just to accelerate your bike to the previous speed), fighting inertia and friction.

When the torque (which is forward force) that you have available is marginal (compared to higher c.c. bikes) and you want to ride fast, you have to be wise about how to use it.

[Somchai]

Some examples of aerodynamic, especially at 0:35 sec

Link to original page on YouTube.

[tgold]

Originally Posted by jkv45

Let me put it another way - look for "significant" improvements elsewhere first. Tenths and hundredths don't make much of a difference if you are 1 second behind - are you battling for the win each time out?

There are certainly areas inside the engine that "blueprinting" is allowed, and there are, according to some people here, large tolerances in engine production of the Ninja. Just doing a valve job (is that allowed?) will most likely yield improvement. Increasing usable power will give you improvements anytime you are at WOT.

Do you have ceramic bearings? Do you have numerous engines, some better suited for faster tracks and others better suited for slower tracks? Have you dyno tested them? Are you changing tires often? There are a ton of things that can be done to lower laptimes. Are you willing to drop another 10 pounds to go .05 seconds faster? Details.

As far as aerodynamics helping acceleration if you are not at WOT - just open the throttle more if you want more acceleration! You are setting the speed - and choosing less than the maximum available - it's not being held back by power or aerodynamics.

Look at weight reduction. That provides improvements a large part of the time (unlike aerodynamics). Reduced weight shows benefits in accelerating and braking, and the percentage of time you are doing either is substantial.

You haven't outlined your ideas on the major aero improvements you are considering. Maybe they will give you the .05 second improvement you want.

What gives you the idea (in anything that I have written) that I have not done or considered doing the "details" that you have mentioned? You want details? I'm thinking of increasing the flexibility in my neck so that I can tuck in better behind the windscreen, so yeah, I think about details.
I will answer a few of them though:
Yes, I am talking about battling for the win. If you are happy with running around in 10th place, then don't bother with what I'm talking about.

Sure, you can do maintenance type stuff but ceramic bearings are illegal in in the class I'm talking about.
Numerous engines??? What planet are you from? We are talking about racing 250 Ninjas for Pete's sake. If I had a budget that allowed for numerous engines, I wouldn't be racing a Ninjette.

The point of this thread is not about doing the obvious things that everybody else is doing. It is about an area that is largely overlooked and looking for a possible untapped advantage. So let's just leave talk about the obvious stuff to some other thread.
I've done this stuff long enough to realize that the people who win are the ones who are willing to do more than everyone else in order to win.

I have mentioned some of the things that I plan to do. As for major improvements, well I've thought long and hard about some of those things and I'm not about to give them away before I get a chance to use them to my advantage first. As I establish that they actually work I'll be glad to share them.

Your last sentence shows that you missed the point that I was making. I used a small amount of time like .05 sec to illustrate a point about its cumulative effect. I never said that it was my goal. I've illustrated several times how seemingly small time savings matter and this is why I'm looking at the subject that I brought up.

[jkv45]

Originally Posted by tgold

What gives you the idea (in anything that I have written) that I have not done or considered doing the "details" that you have mentioned? You want details? I'm thinking of increasing the flexibility in my neck so that I can tuck in better behind the windscreen, so yeah, I think about details.
I will answer a few of them though:
Yes, I am talking about battling for the win. If you are happy with running around in 10th place, then don't bother with what I'm talking about.

Sure, you can do maintenance type stuff but ceramic bearings are illegal in in the class I'm talking about.
Numerous engines??? What planet are you from? We are talking about racing 250 Ninjas for Pete's sake. If I had a budget that allowed for numerous engines, I wouldn't be racing a Ninjette.

The point of this thread is not about doing the obvious things that everybody else is doing. It is about an area that is largely overlooked and looking for a possible untapped advantage. So let's just leave talk about the obvious stuff to some other thread.
I've done this stuff long enough to realize that the people who win are the ones who are willing to do more than everyone else in order to win.

I have mentioned some of the things that I plan to do. As for major improvements, well I've thought long and hard about some of those things and I'm not about to give them away before I get a chance to use them to my advantage first.

Your last sentence shows that you missed the point that I was making. I used a small amount of time like .05 sec to illustrate a point about its cumulative effect. I never said that it was my goal. I've illustrated several times how seemingly small time savings matter and this is why I'm looking at the subject that I brought up.

You've never mentioned anything specific about what you have done (except shedding a few pounds) or want to do, and you just told us you won't.

Ninja 250 engines aren't exactly hard to find for cheap. We aren't talking FZR400s here. The 250 Ninja Land Speed racers that run a couple times a year have numerous engines, so it's not uncommon for a serious racer to have more than one. There are significant advantages available there.

I understand the cumulative effect of minor improvements, but a lot of that is theoretical. Knowing if you actually gained anything on-track, in traffic, is hard to judge at that level. When I told you I tested something by comparing laptimes you said the testing was flawed, so I don't know how you would confirm a .05 second decrease in laptime.

It would have helped if you had given us specifics of what aero mods you were planning to do and on what tracks you were running, but that would have given away your plan, so...

Go for it.

[tgold]

Originally Posted by jkv45

You've never mentioned anything specific about what you have done (except shedding a few pounds) or want to do, and you just told us you won't.

When I told you I tested something by comparing laptimes you said the testing was flawed, so I don't know how you would confirm a .05 second decrease in laptime.

It would have helped if you had given us specifics of what aero mods you were planning to do and on what tracks you were running, but that would have given away your plan, so...

Go for it.

Explained here:

Originally Posted by tgold

So you either test in a wind tunnel or you test on something like a long runway where you can set up a speed trap and accurately measure your entry and exit speed. Some people are actually willing to do that sort of thing.

Aerodynamics are not always intuitive. What is perceived to be aerodynamic often is not. However, there are some general rules that apply. Things like relatively sharp points and edges instead of rounded and smooth, gradually tapering trailing edges in stead of a sharp cutoff, small bodywork gaps instead of large ones.

Originally Posted by tgold

When I say reducing gaps, I don't just mean the gaps between panels, I also mean the gaps between the rider and the trailing edge of the fairing when you look at it from the side. Reducing gaps and smoothing edges costs very little, and (provided you don't crash) requires little in the way of maintenance, but every whack with a horsepower stick costs a lot more in terms of money and accelerated engine wear.

It's not that I'm not going to share anything. I already have shared some things, but you consider them minor. I don't. However there are other things that I think are more significant and I'll share them as I find proof of their effectiveness. I clarified my previous post to reflect that.

I've shared plenty of things before as I've proved their effectiveness on a racebike. An example: The ignition rotor and starter sprag assembly on an SV650 is fairly heavy and eventually it causes the end of the crankshaft to break off on racebikes. Many SV racers simply remove the magnets and then shave down as much of the ignition rotor as much as they can in order to reduce the weight of the assembly and thereby increase crankshaft life. The problem was that they now had a total loss ignition system that ran completely off the battery. I wanted to do that, but I was endurance racing my SV, so a total loss system wasn't a viable option. I looked at what was currently being done and I assessed the needs of the electrical system. Then I removed all six of the OEM magnets, machined the assembly differently and replaced the stock magnets with two small banks of high temperature resistant neodymium magnets. The result was an assembly that was lighter than other total-loss systems yet it retained charging capability.

Stock:

Modified:





I spent a lot of time researching it, documented it and shared all of the pertinent information for free. I'll do the same here as I establish that stuff actually works.

Let's have fun with this. I've done most of the other stuff before and I'd like to try to break some new ground. There are things to learn here about aerodynamics and they should be relatively cheap and effective.

[jkv45]

It's all good. I do understand your perspective and what you are looking to achieve.

I have no problem vigorously debating a subject - as long as there aren't insults or personal attacks - it's all just sharing different perspectives.

I've been on the skeptical side of this debate for the most part (I do believe that aerodynamic drag does exist...), but hopefully there may be something in my perspective that will benefit you or maybe somewhere in here there's a factor that you haven't considered.

Best of luck with your experimentation. Let us know where it leads you.

[csmith12]

[jkv45]

Do elaborate, Chris.

[csmith12]

Elaboration: Just for the laughs. I personally think you 2 guys are in 90% violent agreement and the other 10% from Timm is simply for shits and giggles. If anything becomes of it, COOL!