Aerodynamic fairings - Found!!!

[beatr911]

I ran across this looking at motorcycle land speed stuff. I think it's new on the site, don't remember seeing this six months ago...

LANDSPEED, LAND SPEED RACING, SALT RACER, BONNEVILLE, EL MIRAGE, FAIRING, SEAT, FENDER, SCTA

[Bicycle Bob]

Those are Grand Prix style fairings. To get serious, you need to enclose the front wheel, as outlawed by the FIA in the early 50s when the new streamlined bikes were demolishing records. Vetter remarks on one Harley that ran at Bonneville, first unstreamlined, and then with a F1 style fairing. It got the bike from 100 MPH to 101.

[NeilBlanchard]

This is a fairly aerodynamic stock motorcycle:

[beatr911]

Take a closer look at the link. Along with the GP style fairings they have almost fully enclosed front wheel fairings.

Also these look to be smoother than most GP stylings with the deletion of vents and creases and a brief but existant continuation past the riders leg cut-out.

Vetters experimentation with the Helix hasn't come as far as expected. Using one of these enclosures (or a modified version) would allow experimentation with a wider array of bikes under the skin. Intuitively it seems that larger wheels and taller gearing than the Helix provides will allow the gains Vetter is expecting. I'm suggesting a GZ250 or the new retro-standard bike based on the GZ engine might be an improvement. These are 250cc singles with gearing that can be changed. Additionally, we need a good tuneable closed loop FI system and an overrun clutch on the rear sprocket for coasting.

[derangedhermit]

Airtech also makes at least one old-style "dustbin" fairing, just google "airtech dustbin" for pictures.

Somebody's gonna have to do some wind tunnel work on dustbin fairings in crosswinds before I will mess with them. The Airtech MV one sure looks nice, though.

Also, you guys might enjoy: Schultz Engineering - Electric Motorcycle Aerodynamics

Vetter's still designing fairings like he did 40 years ago, by eye and hand. I think aero engineering has passed by his way of working. But I do like his goal of wanting to make the result a practical ride, and an enjoyable one. I think he picked the right ergonomic position for his goals (feet forward, not head), but he probably would have been better off starting with something he could change the gearing on more easily. If that's a conflict with CVTs in general, I don't know.

My personal opinion on the hp needed differs from his. I think it's a matter of motorcycle safety to have acceleration that can at least keep up with most vehicles around you at low (0-50 mph) speed. 15 lbs all-up weight per hp would be good. For a 350 lb machine with 250 lbs of rider, gear, etc, that means 40 hp. To me 20 lbs/hp is kinda low, and that still means 30 hp - about twice what Vetter ballparks. If you agree with that, then 400cc-500cc is a good range to look in, and even a 650cc single or twin tuned for economy could be a very good choice.

[Christopher Jordan]

Originally Posted by Bicycle Bob

To get serious, you need to enclose the front wheel,.

Most of these are human power velomobiles, but consider a motorcycle inside!

Flickr: The velomobiles Pool

6 pages, I believe. Most of them have an enclosed front wheel.

[dcb]

Originally Posted by derangedhermit

To me 20 lbs/hp is kinda low, and that still means 30 hp - about twice what Vetter ballparks.

a 250 is overkill for keeping up with traffic, even with a tall ratio. I guarantee that speed and acceleration and weight has gotten far more bikers into trouble than out of it. Guarantee it!

Of course it is fun to have lots of power, but it makes the newbies go splat sooner and the experienced ones don't need it to stay out of trouble. The name of the game here is mpg, not misinformed safety school. Most folks looking in would wonder why ride a bike at all if safety is a concern. It just kills me when the safety crud gets brought up as an excuse to use an oversized bike, or any other road tank. It is completely bogus.

[derangedhermit]

Originally Posted by dcb

a 250 is overkill for keeping up with traffic, even with a tall ratio. I guarantee that speed and acceleration and weight has gotten far more bikers into trouble than out of it. Guarantee it!

Of course it is fun to have lots of power, but it makes the newbies go splat sooner and the experienced ones don't need it to stay out of trouble. The name of the game here is mpg, not misinformed safety school. Most folks looking in would wonder why ride a bike at all if safety is a concern. It just kills me when the safety crud gets brought up as an excuse to use an oversized bike, or any other road tank. It is completely bogus.

I agree with most of what you are saying, but you are mainly talking about something different than I am. I think the power available in an 600cc I4 sport bike, or worse, any "liter bike", is absurd and dangerous for legal street riding. They all make 120-150 hp, and weigh 400-500 lbs. Add a rider. So you get a 750 lb motorcycle making 150 hp, for a weight-to-power ratio of 5 lbs per hp. F-I-V-E. If that's what you are talking about, I agree.

The Honda Accord has a weight-to-power ratio of about 18, the Civic (base engine) about 20, and the Fit about 22 (higher is slower). I suggested 20 as a floor, and 15 as very good / preferred. No FIVEs anywhere.

Wanting a motorcycle to accelerate as well as a stock Civic is not bogus, it is not misinformed, and it is not an excuse for misbehavior.

[dcb]

I appreciate that you are operating on perception here, but I go all over the place with well more than 20:1 lbs/hp and wish I could lop off 1/4 of my displacement. I can blow the doors off a metro so it MUST be overpowered It does take getting familiar with your bike and avoiding marginal situations, nothing new there.

[gascort]

Are you talking about horsepower to the wheels or at the crank?
I think my escort has 88 hp to the wheels; 32 lbs/hp.
I'm sure you're talking about hp at the crank. Still...