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- Thread starter D-Man
- Start date
docnjoj
1 GW
Um D-man
Which end of the bike is that?
otherDoc
Which end of the bike is that?
otherDoc
These look great, but how does one know that they actually got the right shape?
I've seen many fairings, but the only numbers I've ever seen were for full streamliners.
The only real discussion I've seen regarding results were from people working on front + tailbox.
I mean, does any old smooth bubble-ish shape work? I really don't know, I'm asking here.
Katou
I've seen many fairings, but the only numbers I've ever seen were for full streamliners.
The only real discussion I've seen regarding results were from people working on front + tailbox.
I mean, does any old smooth bubble-ish shape work? I really don't know, I'm asking here.
Katou
madact
100 W
katou said:
It's a windshield, the jury is out on whether it will be an (effective) aerodynamic aid... that said, it'll likely give you a bigger speed advantage in a time trial than shaving your legs :wink:
D-Man said:
All else aside, it looks very cool - don't recycle it just yet, I want to see the thing in action
Might I suggest a couple of vertical pieces of 1 inch aluminium angle (red), attached to the windshield (black) at the top and bottom (I'm thinking just leave a 'tab' at the top and bottom ends which is bent to match the contour, with a small bolt through the plastic), and mount the thing directly to the ends of the handles of the 'aero' bar (you may need to do something fancy at the ends of the aero bar to still get your hands onto it, of course...), with a triangular brace (blue), also 1 inch aluminium angle from the headstem to the bottom ends of the vertical parts. This should give you all the rigidity you can eat
Actually, looking at your pics again, the aero-bar ends might be a bit narrow... this scheme should work fine with the existing mounts, too, if the new vertical pieces attached to the ends of the existing steel rods, held against the flat bits with the nuts you already have on there. The trick with this is to hold it rigidly at four points so it can't 'warp' (without this, it will twist in much the same way as a picture frame).
madact
100 W
D-Man said:
Maybe just a couple of light-weight rods from the headstem to the lower corners would do the trick? I'd probably use carbon arrow shafts, but only 'cos I have a few damaged ones laying around
Just bodge something on to see if it kills the wobble, then re-implement it tidy-like if it works, I reckon...
That's some nice work D man.
Decent fairings seem to be far and few between when it comes to bicycles and e bikes and the few that I've seen and liked are either unavailable or, very expensive.
BTW, the "jiggling" you mention has always been a big problem on road racing motorcycles (especially with the 125cc and under classes). You may want to consider adding a "bit" of weight to certain areas of the fairing so as to help eliminate the "shaking" or resonance (as the case may be). Motorcycle designers have been using this method for years with handle bars and rear view mirrors with varying degrees of success.
Decent fairings seem to be far and few between when it comes to bicycles and e bikes and the few that I've seen and liked are either unavailable or, very expensive.
BTW, the "jiggling" you mention has always been a big problem on road racing motorcycles (especially with the 125cc and under classes). You may want to consider adding a "bit" of weight to certain areas of the fairing so as to help eliminate the "shaking" or resonance (as the case may be). Motorcycle designers have been using this method for years with handle bars and rear view mirrors with varying degrees of success.
madact
100 W
D-Man said:Thanks.I took it off.
Ah well, the end of an experiment
Never mind, more time to try tail cones, right?
Oh yeah. I might pull the fairing back out some day. I'll try your sketch next time. My design idea didn't work. Figures. I'll use this fairing to drill lots of holes in. If I get it right, I'll blow a new one. I still have some unblown plastic left.
sk8norcal
1 MW
how about just a really small fairing?
remember the profile water bottle from the 90's?
a new version..
http://www.facebook.com/note.php?note_id=64946217644
remember the profile water bottle from the 90's?
a new version..
http://www.facebook.com/note.php?note_id=64946217644
sk8norcal
1 MW
madact said:D-Man said:Thanks.
Ah well, the end of an experiment
Never mind, more time to try tail cones, right?
the tail cone would be challenge aesthetic-wise.. :|
i need to find a pic of my fiberglass one,
it was pretty sexy looking.. :wink:
another one... attached to the frame..
hmmmm....... :|
http://inhabitat.com/2009/08/20/bike-capsule-shields-cyclists-from-stormy-weather/
http://www.bike-wps.com/
mwkeefer
1 MW
I'm sorry but is the tail fairing for Prison Races?
Wow a shield on a Moulton (yea what miles rides), that looks awful familiar - fairly sure that is a scatter shield for a police Harley cruiser from the late 80s?
-Mike
Wow a shield on a Moulton (yea what miles rides), that looks awful familiar - fairly sure that is a scatter shield for a police Harley cruiser from the late 80s?
-Mike
sk8norcal
1 MW
^
am zzipper
http://www.zzipper.com/Products/prod_upright.php
am zzipper
http://www.zzipper.com/Products/prod_upright.php
sk8norcal said:how about just a really small fairing?
remember the profile water bottle from the 90's?
a new version..
http://www.facebook.com/note.php?note_id=64946217644
It wasn't that big. The pictures always make it look big. A couple final pictures as it fell on the carpet to its doom. Not even a test run yet.
sk8norcal
1 MW
i meant that small water bottle thing.. :wink:
too bad there was too much jiggling.. (that's part of the reason I removed mine too)
need more mounting mounts.. (with two, ur fairing needs to be small)
IMO, it looks good..
I ran a couple of wood rods crosswise from edge to edge for stiffness..
too bad there was too much jiggling.. (that's part of the reason I removed mine too)
need more mounting mounts.. (with two, ur fairing needs to be small)
IMO, it looks good..
I ran a couple of wood rods crosswise from edge to edge for stiffness..
madact
100 W
D-Man said:Ok. I have a another idea.Maybe it just needs one more mounting point. I've taken my scrap aluminum mistakes and made some braces. Maybe it will be better. Not bolted down yet. My nose will be pretty close to it though.
That looks like it will do a good job of taking out back-and-forth vibration, probably won't stop side-to-side wibble, but that might not be an issue...
On the subject of the aerodynamics, I found a pretty good animation of the half-cylinder case which is very similar to one of these windshields. The gif on the page is 4.4MB for those on dialup :wink: but well worth the download to get a better idea of the dynamics of what's going on. The periodic vortex shedding (the blue blobs in the animation) are a major source of drag for this kind of windshield, but more to the point, the major factor causing the vibration... IANA fluid dynamics expert, so I can't say what could be done to reduce this (if anything)...
http://www.ara.co.uk/content/2/159/caa-analysis.html (Image: http://www.ara.co.uk/Uploads/gfx/192.gif)
sk8norcal
1 MW
this one from IHPVA papers..
sk8norcal
1 MW
u need 1 hp 8)
here's a bigger one,
here's a bigger one,
