Vetter streamliner body kit

[PeterS]

Originally Posted by euromodder

These kind of humps were on race cars and late model open cockpit aircraft (like the Boeing F4B-4 / P-12E or P-26) back in the day - doubling as headrests, dinghy storage, or hiding the turnover pylon.

The round shape of a head / helmet is the issue here - round shapes at the rear cause extra drag and lead to buffeting (non-symmetric Coanda effects), and should really be avoided. (*)

You could try to cure the helmet - some helmets have aerodynamic features that make the air detach.
Or you could make the helmet into the forward part of a teardrop shaped hump - works best if it's made so that the helmet is usually directly against the fairing.


(*) Due to time constraints, one of the members once made a round (instead of teardrop) boattail for his trailer, and it caused instability to the point he removed it again.

That was what i was suggesting / asking about. So it sounds as if it may be worth incorporating.

[sendler]

Alan has added a truncated fairing behind his head. But this is where he has the license plate mounted so it has to be clear and open to the rear.
.
2013 Craig Vetter Fuel Economy Challenge, Vintage Days
.

[PeterS]

So it would seem Terry Hershner's Vetter Zero would be improved by the addition of a helmet fairing or just raising the height of the rear body ?

[Frank Lee]

I think it would have to be tested. It may have an effect on x-wind performance.

[PeterS]

It might be good to start with an abbreviated version like Alan's then . Fairing my helmet and reducing noise is a high priority.

[beatr911]

Craig Vetter also mounts his license plate, light behind the helmet. Between the helmet and plate is a concave foam pad that is formed to the shape of the helmet. He stated that in certain cross wind conditions placing his "bowling ball" head in the foam socket restored stability. He didn't mention wind noise reduction but it would certanly transfer the drag of rear of the helmet to the tail fairing making less strain on the riders neck.

[Frank Lee]

...making less strain on the riders neck.

Could be mighty bumpy though.

[beatr911]

Frank, I guess I didn't write that very clearly.

When the instability passes he moves his head forward to the normal position. I'm guessing the stability probably comes from adding the weight of the head to the upper portion of the bike. Kind of like a spinning ice skater exends arms to reduce spinning rpm. Well, maybe there is a better example but I can't think of it right now.

In normal riding, adding a passenger transfers the trailing edge drag to the passenger making the driver more comfortable. Same thing with adding a fairing behind the riders head on the single passenger bike.

[stiletto2]

Originally Posted by beatr911

Craig Vetter also mounts his license plate, light behind the helmet. Between the helmet and plate is a concave foam pad that is formed to the shape of the helmet. He stated that in certain cross wind conditions placing his "bowling ball" head in the foam socket restored stability. He didn't mention wind noise reduction but it would certanly transfer the drag of rear of the helmet to the tail fairing making less strain on the riders neck.

It'a about inertia and leverage. Leaning forward a little and not being "fixed" to the bike allows the bike to push over some in the wind. The riders upper body pivots at the waist approximately and the bike is allowed to rotate freely; or at least relatively so around that "unattached" mass.

Consider 2 weather vanes; 1 with weights close to the axis of rotation and the other with duplicate weights but mounted much further out from the center of rotation; so both vanes are of equal weight. The first one swings easily in the wind because of the mechanical advantage of leverage that the vane provides by having more of the mass closer to the pivot axis. The wind is not as effective at moving the other because it does not have as much of that mechanical advantage and has to overcome the inertia of the mass that is further away from the pivot axis. A body at rest tends to remain at rest; a body in motion tends to remain in motion unless or until acted upon by an outside source...... Elementary dear Watson, elementary.

[stiletto2]

Originally Posted by stiletto2

Consider 2 weather vanes; 1 with weights close to the axis of rotation and the other with duplicate weights but mounted much further out from the center of rotation; so both vanes are of equal weight.

Actually, for clarification, since weight is not being moved per se, it's more like one vane where the weight is sitting on top and allows the vane to freely swing independently of that weight and the other where the weight is firmly attached to and rotates with the vane. The wind is not as effective at moving the one with the weight firmly attached.