[Cycle]

Originally Posted by ChazInMT

I can't put it in any other words....

If you add energy to the air by "Pumping it" the energy has to come from somewhere.

Yes, it comes from the engine exhaust... at highway speed, it'll be putting out about 567 liters of air per minute.

Originally Posted by ChazInMT

Your engine exhaust is a squirt gun against the Hoover Dam, the volume of air needed is HUGE to accomplish what you're asking. HUGE volume of air will need a substantial energy source.

The Coanda Effect nozzle multiplies the air flow, especially considering that we're pushing high pressure air from the front of the bike, heating it up in the engine compartment, then exhausting it into a lower-pressure area.

Dyson claims a 15x increase in airflow over what their hidden fan itself provides. At even 10x, I'd get 5671 liters of air per minute (not taking into account the fact that the air is hotter due to absorbing engine compartment heat, and the exhaust heat isn't factored in, either). That's about 200 CFM.

On a small aerodynamic bike, that'd go a long way toward filling the wake.

Originally Posted by ChazInMT

For the amount of time, energy and money as you would put into such a system, you could just design it into an aerodynamic shape from the get go and have an efficient vehicle.

Yeah, that'll be done, but while the entire bike is being built from the ground up, why not include those small areas of energy savings that make it that much more efficient? It's a project bike, the aim is to get as high a fuel efficiency as is possible.

Originally Posted by ChazInMT

Bottom line....It takes energy to move air, the object of the aerodynamic game is to move it as little as possible as we plow through it.

Think about how much power it takes for a fan to blow air across a room, it's moving maybe a few hundred cubic feet per minute at 15 MPH. What you want to do is asking for thousands of cubic feet at 60 MPH. But you know what, even if you could get unlimited free energy, this concept of "Filling the Vacuum" is doomed from the start because that's not the way it works.

Except that is the way it works. That's why the examples provided by others in this very thread work to reduce wake drag.

Originally Posted by ChazInMT

Follow with me.

You plow through the air.....It is only trying to get out of your way and get back to where it was before you came crashing through it. The car is moving, the air is stationary.

The more you move the air as you plow through it, the more energy it takes, just like a fan requires more power to move a larger volume of air at a higher speed.

So you're saying you're not only going to move a huge volume of air to plow through it, but you're also going move another huge volume of air to compensate. And you'll be more efficient.

Yes, because we're (at least partially) negating that low-pressure area at the back of the bike that's literally "dragging" on the body of the bike like an anchor, in addition to moving some of that high-pressure at the front of the bike that's literally "dragging" on the body... pressure and wake drag. The more you get rid of them, the more efficient you'll be.

Originally Posted by ChazInMT

Here's another thing you can do, explain how this would work on a boat?

Imagine, if you will, a Ski-Doo... except the jet is powered from otherwise wasted energy.

Originally Posted by ChazInMT

On a boat going through the water, you can't just pump a bunch of water into the wake to make it go away and make it more efficient, you would require as much energy or more to fill the wake as it takes to get the boat moving at speed to begin with. So how can 2 engines running at full power be more efficient?

It wouldn't be "2 engines running at full power"... you do realize that approximately 2/3rds of the energy in a gallon of gasoline are expelled as heat, rather than being used for propulsion?

Originally Posted by ChazInMT

I see you're probably talking about motor cycles here, so you're doomed from the start in aerodynamics due to the fact that you're shoving a big lumpy sack of potatoes through the air at high speed.

The aerodynamic complexity of a motorcycle would melt several supercomputers running in parallel trying to make mathematical sense of it if you could come up with the formulas to input in the first place.

You're making the assumption that the bike won't be designed to be aerodynamically efficient, just as you're making the assumption that the energy to pump that air into the wake isn't otherwise-wasted energy.