Building fairings

I had a sinclair... :roll: But hay, they were real.

Dang, I wuz just in NYC yesterday! (family mission, no time for fun. )

I don't know for sure, but I mighta seen yer bikes in town during the eighties/nineties when I lived there. (I used to rollerblade in CP on the weekends )

I can say for sure that I have seen the dude with the confessional on his bike, but that is certainly not helping his aero.
 
Lowell said:
I'm interested to see how that fairing compares to the RRF. Can you tuck behind the bubble with the windscreen so close?

I rode in the rain for the first time since installing my fairing/screen and it's awesome. Barely any water got on my jacket, and mostly at stop lights. Once up to speed and tucked in at 50+mph, rain drops don't stand a chance.
Click to expand...


Hi Lowell,
You're right, I can't tuck behind the fairing, on either the RRF or the TD1F. That is something worth working on. Looking at the above examples, they tried to get the faring out in front of them. there must a "ying and yang" of keeping it close enough for the flow to stay "clean" yet far away enough to be able to tuck in.

It seems in sailing and biking, it's all been tried before (100 years ago), the information is just "lost in time". But then they didn't have pre-preg carbon fiber to use, so maybe there are a few new ideas out there yet.

I too, took a ride in which turn to rain the other day, The poor cardboard got wet, but keep me drier.

Small changes to the TD1 fairing's width has been resulting in interesting results. A little wider makes for faster mid range speeds, but lower top end speeds. So a little tweaking here and there for the different speeds will be needed. It looks what you'll need at 50-60 mph and what I'll need at 25-30 mph could be somewhat different.

It's been pretty windy here lately, so testing for soild numbers has to wait.
But riding 10-15 mph with a fairing into 15-20 mph with higher crosswind gusts has given me a feeling for the thing. I still don't like having much "side area" for the downwind trip though don't notice on the upwind leg. I think that having the fairing centered on the front fork (Front to back) helps the crosswind thing, but makes it harder to "tuck under" at higher speeds. Hmmmm?

Lowell, Keep those eyes Wide Open at those "eyepopping" speeds.

Later Kyle
 
TD1 Fairing pattern

Pretty Basic

Have at it :D

Kyle
 

Attachments

  • TDF1.pdf
    19.6 KB · Views: 137
Suspension?

One of the problems with adding suspension other than the price and complexity (which is managable) is the fact that it increases the problems you have with getting clearance between the front wheel and the fairing you might use.

If you raise the front end by 3" so that you can have suspension then the frontal area will increase by 3" times the width of the bike.

One thing that the motorcycle road racers do is raise the front and rear end at the same time and have the fairings match proportionaly and then when in a turn the suspension compresses (naturally) and it gets you closer to the ground your center of mass is lower, so the turning is okay. A high center of mass squashes low.

So it's a difficult question...

If you REALLY want to lower the frontal area then the front wheel needs to be practically rubbing against the frame and the head tube needs to be short enough so that you can lower your head down near your hands. On my current bike I get into such a tight little ball that the wind resistance seems to disappear. With an actual fairing it would be even better.

A lighter weight bike (than my current one) would also be able to go over the bumps pretty well if you allow your arms to "go with the flow". The biggest problem with a non-suspended bike is the seat... when you hit a bump at speed your arms have no problem, but the pounding you get from the seat is pretty uncomfortable. (and your legs have difficulty supporting you in a tuck)

:arrow: So that's why I'm thinking of suspending the seat alone... it's the "most needed" suspension...

:idea: Thoughts?
 
safe you raise some good questions/ideas.
I too, remember hitting the seat pretty hard on my road bike.
It would help alot with the bumps.
Are there any downsides to peddling a suspension seat?

There are inherent problems with any bike style you choose.

For total Areo reduction, one could start with a road frame, narrow high pressure tires, stay in a tuck, have a fairing and don't forget, suspending the seat too.
Good aero qualities, but for me, the rattling on a 50 mile ride on a stiff frame with hard tires is tiring.
It's a hard one to quantify, but I suspect that a suspension saves some of that abuse.

A 'Bent, would be a better start yet, but I nix that idea as I want to be able to look "that SUV owner in the eye".
But the comfort and aero dimensions look enticing.

The suspension system itself is aero unfriendly. Just covering up the mid-frame of a "Y-frame" results in a 1 mph increase @ 25 mph.
But a Suspension bike with a fairing, gives a comfort level that keeps me on the bike longer and willing to ride more often.

I'd bet that you would get close to the results of your tucking into a tight little ball with a fairing without tucking.
You'd get the benefits of being in a ball, the whole time, while sitting more up right.

It seems a fairing is useful from 20 mph and up.
At the Speeds you and Lowell are going, I would think a fairing would go a long ways.

You are right, it is a difficult question, A complex one.
There are many conflicting and compounding components to design around.
The numbers from the 'bent guys' fairing research actually show a bigger increase from a "rear" fairing than a front one.
Basically controlling the "tip vortex" that wings experience.
Airlines save a bunch fuel with those little wing tips by reducing that vortex.

With your ability to build frames, it's going to be fun to watch your bike's evolution.
I can tell the 'wheels' are spinning on your next creation.
Can't what to see it, I assume that it will out of the "Box".

CAUTION: "Brain Fart"
How about a suspension seat with the ability to raise and lower the whole thing like the "spring raise/lower" seat posts that the mountain bikers' have?
Actually that would help me get down a bit lower, Hmmmm....

Later
Kyle
 
Kyle said:
Are there any downsides to peddling a suspension seat?
Click to expand...

I'm not considering sitting while pedaling... my bike would expect you to stand to pedal, mostly at slow speeds and up hills.

Kyle said:
Good aero qualities, but for me, the rattling on a 50 mile ride on a stiff frame with hard tires is tiring.
It's a hard one to quantify, but I suspect that a suspension saves some of that abuse.
Click to expand...

The seat will keep your back from taking a hit. My 3" tires also absorb a lot of energy, but my arms do get tired after a while. Ideally about 1" of really good suspension travel is all I would want or need... you don't need much.

Kyle said:
I'd bet that you would get close to the results of your tucking into a tight little ball with a fairing without tucking.
You'd get the benefits of being in a ball, the whole time, while sitting more up right.
Click to expand...

The best is being in a tuck and also having a fairing which is the plan for the future bike. I simply haven't built a fairing for my present one , but would love to have one.

Kyle said:
The numbers from the 'bent guys' fairing research actually show a bigger increase from a "rear" fairing than a front one.
Basically controlling the "tip vortex" that wings experience.
Airlines save a bunch fuel with those little wing tips by reducing that vortex.
Click to expand...

No doubt that the rear is important. The front mainly needs well shaped edges on the sides, the center area becomes a pressure area and as long as it's sealed the air produces a "virtual fairing" pressure zone that divides the wind. Aerodynamics is a complex topic, but frontal area is simple... it's harder to make something wide in front go fast..
 
safe: "the center area becomes a pressure area and as long as it's sealed the air produces a "virtual fairing" pressure zone that divides the wind."

Could you expand on the above idea? I think I get it.......???

safe: "frontal area is simple... it's harder to make something wide in front go fast.. "

You are right, it's hard to get away from "total frontal area" being a big factor. But it might not be as simple as we would like. When I flaired the TDF1 out 2" on each side (bigger overall frontal area) I had slower top end speeds, but higher mid-range speeds. What speeds you are designing for comes into play.

safe: "I simply haven't built a fairing for my present one , but would love to have one. "

Hey, cardboard and some tape will get you started. I see a few prototypes in your future. I'd been interested in what you come up with.

Later
Kyle
 
Kyle said:
...air produces a "virtual fairing" pressure zone that divides the wind."

Could you expand on the above idea? I think I get it.......???
Click to expand...

I remember people discussing the front fairings on motorcycles and apparently in the wind tunnels they realized that a flat plate surrounded by an aerodynamic rounded edge produces drag that is not that far from a fully aerodynamic shape. A "pocket" forms in the nose and it deflects the wind around and as long as the shapes on the sides are right you keep a streamlined flow. This leads into your next thought...

Kyle said:
I had slower top end speeds, but higher mid-range speeds. What speeds you are designing for comes into play.
Click to expand...

You probably were creating "eddy currents". That's a big factor on regular bikes when the rider is pedaling. Apparently the rotation of the legs produce this oscillation that really adds a lot to the drag. Some airfoils work without creating eddy currents up to a certain speed then they "go wild" and the drag goes way up. In a "perfect world" a fairing would best be built when you had access to a wind tunnel or some extremely complex computer simulation software. There is some free software out there to simulate aerodynamics, but you might spend a month getting good enough with the software to actually begin to see some results. I don't have enough time for that.... (it took me three months just to develop my spreadsheets for electric bikes!)
 
You're probably getting flow separation early on. Tape some wool tufts to your bike and observe them as you ride.

http://www.autospeed.com/cms/A_3061/article.html

PDF version:
http://www.mitsubishi-motors.com/corporate/about_us/technology/review/e/2004.html

web version:
http://www.autospeed.com/cms/A_3059/article.html
 
Re pedaling on a suspension seat: I've had the chance to try an old fashioned sprung saddle and a telescoping seat post. Both had the same issue: At a certain RPM, a sort of feedback loop happens that's really annoying, so I found myself staying either above or below this frequency, but both would be fine for no sweat cruising... Found the saddle with springs worked better, as the telescopic seat post suffered from sticktion on smaller bumplets such as rolling over small rocks or cracks in the pavement. They also rob some power, kinda like a dual suspension bike, except that when you drop the hammer the bike really accelerates instead of looking cool bobbing up & down...

On topic content: It's guesswork to dial in seat height with so much mush in it, and I got the feeling they lend themselves better to a somewhat more upright/relaxed stance. So, as far as I can tell getting one of these would most likely hurt aero. Your mileage may vary.
 
RRF test Correction :oops:

I have a 408/4011 C-lyte hubmotor with 36-72v 20 amp controller that has a 3-way switch: 4011-off-408.
On the RRF test on 6th street hill I errored by having the control switched to 408 on the RRF run (30.3) and by having the control switched to 4011 on the "nake" run (24.6). This gave an incorrect result which to Knoxie just didn't smell right. Kudo's to Knoxie for giving it the Trademark "Knoxie's Smell Test". I apologize to Knoxie&all for not re-checking sooner. (Note to self: if someone smells shit, it might be time to check your shoes.) A rookie mistake not knowing there would be different amounts of drag from the same motor. So I stand corrected. The RRF speed increase is about 8%. The TD1F increases this to the 15%+ range.

Comparable roll tests I've done on Court St. hill shows the resistance of the hubmotor:
Switch to 4011 24.6 mph max
Switch to "Off" 27.8 mph max

So there can be a real drag from the hub motor on the 4011 setting at 20 mph +/-, on the 408 setting I imagine the same thing happens, just at a proportionately higher speeds(35 mph +/-). By turning the switch to "OFF" the drag largely goes away.

Again, My apologizies to Knoxie for not giving his comments more credence. It's good to have some one double check one's work.

The point is still valid: a Fairing can save considerable Watts.
But my forum etiquette was sub-par.

The numbers from 2nd round of fairing test.
The TD1 Fairing.

Starting at the SE corner of 10th & Court Streets with a small push off to get rolling, I rolled down to 4th with no pedaling, usually sitting up right. Wearing the same clothing and bike trim. The controller switched to "off". Using a Garmon GPS for speed. No Wind.

The Run down Court St. provides 4 gradually steeper sections follow by a flattening 5th section allowing for slowing before the 4-way stop sign.

It is a good course as it has allowed me to see the differences between the various fairing configurations at increasing "power" levels(slopes). And still have time to come to a safe stop.


Type
Regular Nake Bike (Bike) top speed 27.8 mid-way speed (mph) 20.5

(Bike) w/ mid-frame cover (Bike2) top speed (mph) 28.9 mid-way speed (mph) 21.6

(Bike2) w/ TD1 fairing top speed (mph)31.5 mid-way speed (mph) 22.5

(Bike2) w/ TD1 fairing w/ "ConeAss" top speed (mph)31.5


(Bike2) w/ TD1 fairing & tuck top speed (mph)32.3

(Bike2) w/ TD1 fairing & seat
lowered 4" and tuck top speed (mph)32.7

(Bike2) w/ TD1 fairing
modified w/ interior enclosed
seating upright top speed (mph)32.3 mid-way speed (mph) 26.5


(Bike2) w/ TD1 fairing modified
on 4th St. Hill rolling start top speed (mph)34.1



I took one run with the RRF on the Court Street course and it was in the middle of the speeds, as I remember it. (Sorry, it's back to work for ol' RRF.)

I have taken the TD1F on 4-5 long trips though some strong gusty winds (10-20+ mph) and was glad to have it. Didn't get blown around too much, it was better on the downwind leg than the "RRF". Glided away from some road bikers on a downhill going 20mph+.
On the other hand at 13-14 mph, I'm just a bit slower.

Looking at the numbers, one could guess that it's working well in the 20's mph, by 30mph or so the air flow is starting to fail. Haven't tried strings yet to see what is going on.

The speed increase are 4% for just the mid-frame cover and 16% with the TD1F, with even higher increases in the mid 20's mph.
These gains seem modest until you discover the amount of watts they represent.("Your mileage may vary.")

I've been using the "trunk-space" in the TD1F for holding the on-board charging equipment, a lock, maybe a small pack, half-eaten burrito.....
Love having on-board charging, it rewarms the burrito.

Later
Kyle
 
Another pattern for your fun and pleasure.
Haven't had a chance to make this one up yet.

Kyle
 

Attachments

  • tdf2.pdf
    35.3 KB · Views: 161
ok i realise i've come in to this discussion a bit late but i've been reading your posts and think i've cracked it.

what we want is a cheap, transparent, thick plastic bubble shaped fairing.

a search on Ebay for things to "backwards engineer" revield this
http://cgi.ebay.co.uk/Tummy-Tub-in-...9QQihZ003QQcategoryZ20395QQrdZ1QQcmdZViewItem

a baby bath, cut in half, then bolted together at the flange area. putruding plastic cut off. this would provide excellent streamlining for a rider for a price of just £20. its transparent so it wont stick out like a sore thumb and you can see through it when tucked.

it could easily be fitted to the handle bars with 1" copper tub flattened at the ends and bolted.

i've ordered the bath and i cant wait to try it out.
 
monster said:
i've ordered the bath and i cant wait to try it out.
Click to expand...

Wow. I never would have guessed someone could top the weird-factor of the RRF..

But now we have the TTF.

Game-on. Even Charles Goodyear looked goofy in rubber outerwear, but then he discovered vulcanization and became rich. Nobody thought he was goofy after that. (Of course, Ross Perot is rich and looks goofy; so go figure.)

:D
 
i was just using the online power calculator thing and there is a 10mph difference between hands on tops and hands on drops.

i want that 10mph! :D

only thing is that curved "racing" handle bars have two hand positions and i would want to use them both. is it possible to fit two controlers to your crystalyte controler for this purpose? how would i connect them? in parallel?
 
Fun thread.
Somebody sometime/somewhere mentioned Lycra. Guess I mis-heard this, and bought Spandex. I'm building a "fairing" sort off... but actually an exo-frame. (exoskeleton?)... the shape looks like this:
a232_210.egg.jpg
`cept narrower at the top...
App.is a power-assist kick scoot, the worst aero on the planet. Ya have to imagine that egg w/a Crystalyte hub motor sticking 40% outta the bottom, and a slice down the side of the "egg" that folds out/down and locks, as platform w/lithium. Plus handle bars that then fold out and lock. Inside hollow, w/enough room for two bags of groceries plus newspaper and a six pack.

Anyway, the Spandex was NFG. It stretches in only one axis, and between the top/bottom "hard" bits of the "male" mold it "shrank" rather than provide a smooth continuum to be covered with glass and kevlar w/resin (poly, not epoxy). So, is Lycra better? Don't care! Bought unbleached (no-stretch) cotton, instead. Always looking to buy stuff that'll rot behind me. Will have to get back to you re bamboo strips+resin at some point.

Anyway, I am not interested in high speeds, but instead high speed *ambient* air... usually somewhere off the bow... errr, I mean, for lubbers, not straight from the front (aka sideways.)

I think this "aero" looks terrible:
sf40blu.jpg


tks

Lock
 
check out this fairing, for three kids an adult.... http://www.youtube.com/watch?v=5pPIVST2r_Q&mode=related&search=
 
i tried this today. i didn't see any speed increase.


maybe i'll try again in future but i felt the high dork factor and its off the bike for now.
 

Attachments

  • Dsc00183.jpg
    Dsc00183.jpg
    120.9 KB · Views: 2,137
The lower half is probably ok, but the upper section needs to sweep back like a sport bike windscreen.
 
You must log in or register to reply here.
Back
Top