Buddfab vs. Nebulous 4:

[Rex Schimmer]

First I want to say a really big "Way to Go" to the Buddfab guys, 150 mph with only 50 cc's is really an acheviement!!!

But the real reason for this topic is a result of reading the Buddfab web site and a comment they made regarding setting the 100 cc class record. They mentioned that they exceeded the Nebulous Theroem 4 record for the class by 10 mph. Doing a couple of quick number that would mean they if both bikes have the same Area x CD number then the Buddfab engine made 28% more power than the Costello engine. Of course they do not have the same Area x CD number and my guess is that the Nebulous 4 probably has a smaller frontal area, so if we assume that they have equal horse power then the Buddfab bike has a 28% smaller Area X CD number and if the Buddfab bike has, as I think it does, a larger frontal area then its CD is much smaller than the Nebulous Theroem 4 bike.  These two bikes are trully great examples of two different aerodynamic design "schools". The Buddfab is a classic NACA derived shape ran a sufficinet ground clearance to allow air to flow beneath it without becoming turbulant and un attached, the Nebulous Theroem 4 is the "Costello" design school of a very small frontal area with a flat bottom running at a very small clearance with the ground.

I am not sure what the 100 cc engine was in the Nebulous Therom 4  when it set the record but I did watch it run 214 in August with a Honda 250 single and again doing some backward engineering and assuming that the 250 Honda was probably good for 45 hp then the 100 cc motor would probably be around 13-14 hps so maybe the answer is that their engine was not as powerfull as the Buddfab engine. I would certainly expect a Honda CRX100 two stroke to be able to put our 20-25 hps with out much problem.

Jack if you read this please "dilute" our ignorance regarding the power of your 100 cc engine if you have a good hp number. The reason I bring this all up is I am presently designing a small engine lakester and I am wondering if I should make it flat bottom, the Costello school of design, or round body with good ground clearance the "classic" design.

Your thoughts please.

Rex

[interested bystander]

Rex, your comments pique my interest in the small cc speed classes.

The two approaches are certainly oposite, Buddfab and Neb 4.

 I contend that CostellA has the more controllable platform, but BOTH Buddfab guys ride their machine and I don't think its fallen over yet. I'm thinking the two's CdAs about equal.

I do have a displacement answer on CostellA's 100cc record attempt motor- it was only an 80 (from him to me at WF 2004).

To mention the 50cc class, it's been published that the BLOWN Kreidler of the '60s made about 15 HP (145mph) and I think the Buddfab guys have talked 18.

Some of the Pocket Rocket Italians bikes in 50cc GP form CLAIM, unblown on 92 octane, 18HP.

Different approaches aside, both efforts impress. 

[RichFox]

I believe that it is correct Jack Costella was using an 80cc Honda motor. I was just down at Bud Fab looking at his very pretty bike. What I saw was an Aprilla and a tenesy tiny turbo charger. Have no idea what was in the bike for the run in question.

[Viking Biker]

Rich Rex, You may want to do a search for and read all the posts by Blue (Eric).

-Jason

[Dr Goggles]

I too am fascinated by the "petite" end of the landspeed pursuit and despite HWNSNBMH* and his assertion that any records other than the ultimate speed records are meaningless I am convinced that it is at this level that there is a great deal to be learnt. When the Budfab begins running bigger engines ( I gather that is the intent) there will be a wealth of info available that will be useful in drawing up even finer conclusions about Cd/traction/mass/power relationships .The basic comparison between the two shapes is interesting enough. The fact that Sam Wheeler's EzyHook is in the running against the other top liners is an indication that we still have a lot of room for aero design with given power levels.If it was just about power it wouldn't be anywhere near as interesting , 50cc going 150mph says to me that this game is way , way from over yet and everyone with an engine bigger than that has a job to get on with....as you were men.


He Whose Name Shall Not Be Mentioned Here

[willieworld]

7.H Streamliner
A Streamliner is a motorcycle designed so that it is not possible to see the complete rider in the normal riding position from either side or above. Wheelbase is unlimited and shall make a single track. Power shall be transmitted through the rear wheel only. Steering shall be done with the front wheel only.

The vehicle, unloaded, must be capable of being leaned at an angle of 20 deg. (minimum) from the vertical position without touching the ground, other than the tires, without prior contest board approval.

i think that ends it right there   that rule makes all of jack bike liners illeagle               willie buchta

[Seldom Seen Slim]

Well, there is a caveat in there -- "...without prior contest board approval."

I'm not going to fight the fight to get Jack's bike liner's allowed -- but that line leaves some room for discussion, doesn't it?

[willieworld]

my money says " that will never happen "   any takers--------------willie buchta

[Stainless1]

Nothing like a rule without scientific foundation to eliminate innovation... I guess Jack is still on the scta shit list 

[Stainless1]

I received this PM from another member, I thought we should all see it (without revealing the sender) as it adds to discussion.

Who said that no research was done? Is a motorcycle supposed to ride on the chassis instead of retractable skids. The thing has rolled three times because of the frame rails digging in.

First a motorcycle rides on its wheels, not on the skids or chassis, those parts only contact the ground until it can be righted onto its wheels and when you try to stop. 
Second, we may need everyone's help on this one, please name any motorcycle streamliner that has not crashed.  Sorry to bring this part up, but they all probably will if anyone can think of one that has not.  It is the nature of the beast.   

Why stifle innovation?  Are flat bottom cars next? 

[willieworld]

if research was ever done ( and i doubt it was done by any real experts ) it was never published so the rest of us ( chassis builders ) could build accordingly ---just some kneejerk rule changes- willie buchta

[John Noonan]

Bob,

I don't believe the Budfab liner has crashed?

[Anvil*]

For a given sized rider I believe the Buddfab layout has a better Cd. My little group has been examining pictures and sketching layouts for a couple of months now and with the desire to keep motorcycle wheels a Buddfab style layout was the only one that got all the bits to work well together. There may be a size break between the two designs however.

Things can change very quickly at higher horsepower and speed levels. A neutral shape is undesirable and added downforce with minimal additional drag become necessary. That additional horsepower has to hook up and ballast only gets you so far. No, this isn't an area where I have years of proven experience but there is a fair sampling of what worked with examples of brute horsepower and slick aerodynamic shapes (including some small riders). It's interesting to me because there is no single solution.

[1212FBGS]

willie
excuse me but i cant find in the rule book where the SCTA needs to publish there research to anyone..... hey dude ya might want to run spell check on your post.... i don't think i ever saw "illegal" spelled that way before... or perhaps your talkin about a sick bird?
Kent

[RichFox]

I have not heard Jack complain. last I heard he felt the rule was very fair.