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Victor Ragusila
recumbent enthusiast

Canada
352 Posts

Posted - 05/26/2012 :  09:31:58  Show Profile  Reply with Quote
Hello Everyone

I raised the issue of the NoCom chain stays being aerodynamic devices to shield the rider. I am opening this can of worms in a separate thread at the good advice of Sean.

So the rules say that :

"The vehicle construction shall be such that its shape does not overtly direct airflow around the rider's body, nor attempt to reattach the airflow behind the rider by use of tail fairing devices. The only exception being the use of an aerodynamic shaped helmet. The vehicle can incorporate aerodynamic
fairings to make its structure and components more aerodynamic. Allowed fairings are: rotating wheel covers and splitter plates."

Now my question is two-fold:
1) first, are the chaistays able to re-attach the flow? I do not have a NoCom unfortunately. A tuff test on the chaistays would indicate whether the airflow is attached (all the tuffs are nicely pointing backwards) or detached (the tuffs are randomly moving along). The M1 Lowracer that Mike rides has even bigger chainstays, and it would be interesting to see whether that one has any attached flow.

2) If the flow IS attached, are the chainstays legal? I see an argument possible for each possition:
ProChainstays: They are a necessary bike structure, not an extra tail fairing that is there to only improve aero. Their big cross-section is necessary for structure stiffness.

AntiChainstays: They could be much narrower and have the same structural properties, yet they are shaped that way to improve the aero behind the rider, specifically to fair the torso.

I am curious if anyone is able to do a tuff test. I can try to set one up at Kenosha or next year Michigan, if anyone wants to volunteer their M1 or NoCom. The tuffs are easy, we would need someone with a decent camera riding besides the NoCom at low level to film it.

I do not raise this thread to bring anyone's records down. I want to understand the aerodynamics behind these bikes, as well as the rules regarding each class of competition.

Victor

Edit: Reading my original entry in the thread about Aure's record attempt, I realize that I was implying that there is a double standard in the technical specs. This was NOT my intention, and I do apologize that i sounded that way. I do not think it is anyone's intention to have a double standard. I was not clear on the rules, and I realize that there is a lot of interpretation that needs to be done.

Edited by - Victor Ragusila on 05/26/2012 09:39:32

warren
human power expert

USA
4902 Posts

Posted - 05/26/2012 :  12:51:38  Show Profile  Visit warren's Homepage  Reply with Quote
Hi Victor,

Being a current NoCom owner, and having built and ridden with several tailboxes, I can say that because the shoulders are significantly wider than the chainstays, the air in that area is turbulent. I have not performed a tuft test. Maybe it will show that the turbulence is all going in generally the same direction rather than a giant sucking hole. Maybe I will have time to tape some on before our next ride.

-Warren.

-Warren.
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Larry Lem
human power expert

South Sandwich Islands
2302 Posts

Posted - 05/26/2012 :  13:22:51  Show Profile  Reply with Quote
Whether the tufts remain attached or not, do the chainstays help reduce aerodynamic drag and therefore act as a mini-tailfairing (whether very effective or barely effective).
One would have to do a coastdown or other type of power/speed/drag test of a bike with "normal" stays, and then the same bike with material added to mimic the shape of the NoCom stays. Or of JM's bikes.


Larry Lem
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randy
recumbent guru

721 Posts

Posted - 05/26/2012 :  14:16:55  Show Profile  Reply with Quote
I don't think it matters, the seat angle is too steep. Those stays are penny-wise pound-foolish (when considering unfaired hour-record bike design).
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Speedbiker
human power expert

USA
2467 Posts

Posted - 05/26/2012 :  14:47:27  Show Profile  Reply with Quote
Woo hoo, my kind of thread! As a self certified aerodynamic engineer of the first order, here is what I think. Real aero engineers please try and shoot me down. Firstly, most of the people spouting this idea are keyboard jockeys on another forum. I generally agree with the previous posters. It is EXTREMELY unlikely the stays on a NoCom or M1 increase speed. For that to work not only would a large amount of airflow have to reattach, but it would have to do so over a large enough area to improve pressure recovery. That is why a Razz Fazz TF worked. It is also why many well crafted TFs help speed very little. You have to reorganize a large amount of turbulent air. A pair of stays riding in the turbulent air behind your shoulders isn't likely to help. Then, why are the bikes so fast? I believe it is due to the streamlining of airflow between and around components. Especially the cranks, seat, and wheels. I am not a believer that splitter theory exists anywhere but in windtunnel experiements. What most people think is splitting is actually streamlining. But, if splitter theory does exist, you should outlaw large back wheels(then only my bike and the Gritters will be legal.
End of disertation. Opposing views encouraged(along with proof).

Thom Ollinger
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W Hilgenberg
recumbent enthusiast

USA
285 Posts

Posted - 05/27/2012 :  08:44:38  Show Profile  Reply with Quote
Concerning splitter technolofy, I've been doing a bit of reading lately and have come up with this;

http://www.sciencedirect.com/science/article/pii/016761059290520K

Unfortunately it isn't the full text (I have a copy of this at my school library)but as you can read in the synopsis below the splitter doesn't really do that much when considering all of the vortex shedding off of the rider and frame components of a double diamond frame. When compared to a recumbent, I believe that the conclusion is still true considering that you have your feet ahead of the front wheel and the rest of your body in front of the rear wheel.

With regards to the stays providing some aerodynamic improvement, I would imagine that they probably don't reattach the flow from the rider (there is a slim possibility of that though. . .) they do most likely aid a little in the pressure recovery. Not much but a little. But I don't have any proof of that and we should to a tuft test.

Lastly, sorry for being a bit AR but it is tuft not tuff Victor.
http://dictionary.reference.com/browse/tuft
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W Hilgenberg
recumbent enthusiast

USA
285 Posts

Posted - 05/27/2012 :  08:46:51  Show Profile  Reply with Quote
Although, I would assume that a tuff test could be rather interesting. . .

http://dictionary.reference.com/browse/tuff?s=t&ld=1030

Don't think gluing on tuffs would help much with figuring out what the flow is up to.
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Larry Lem
human power expert

South Sandwich Islands
2302 Posts

Posted - 05/27/2012 :  09:42:40  Show Profile  Reply with Quote
Hey, it's tuft. What did they teach you at that silly college? (alumni of same college...)

http://dictionary.reference.com/browse/tuft
1.a bunch or cluster of small, usually soft and flexible parts, as feathers or hairs, attached or fixed closely together at the base and loose at the upper ends.
2.a cluster of short, fluffy threads, used to decorate cloth, as for a bedspread, robe, bath mat, or window curtain.
3.a cluster of cut threads, used as a decorative finish attached to the tying or holding threads of mattresses, quilts, upholstery, etc.
4.a covered or finished button designed for similar use.
5.a cluster of short-stalked flowers, leaves, etc., growing from a common point.

http://dictionary.reference.com/browse/tuff?s=t
a fragmental rock consisting of the smaller kinds of volcanic detritus, as ash or cinder, usually more or less stratified.

Larry Lem

Edited by - Larry Lem on 05/27/2012 09:43:03
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Upright Mike
human power expert

USA
3463 Posts

Posted - 05/27/2012 :  10:30:31  Show Profile  Visit Upright Mike's Homepage  Reply with Quote
For me, the proof is in the results...
On my Challenge lowracer with a high seat-back and likely higher turbulence, my best for one hour was about 25.5 mph (41 kph).
On my Morciglio M1 lowracer with lower body position, wider stays perhaps fairing in my back better, my best is 27.7 mph (44.6 kph)
These results were on the same 6 mile loop course (Stony Creek) that I've ridden hundreds of times.

The only time I felt slow, was when my seat pad fell inside the chainstays. This created a pocket for air to be scooped up inside the chainstays. So air can enter the chainstays. John might argue with me that it can not, but his shoulders and everyone's are different. I need to add some more padding to fill in my gap behind the shoulders and seat pad.

John wants everyone to know that when he builds them a M1 lowracer, he will leave the chainstays "uncut" or with extra forward material. Then if the person picks up a bike from him, he will carefully cut the chainstays back to line up with their shoulders best.

I feel that my BEST speed comes from when my shoulders are raised a bit above the chainstays, rather than aligned within them. I think it does reattach the flow better. Last year my bottom bracket was moved back forcing me to sit up more and ride with my shoulders above the chainstays.

I was going approximately 1 to 1.5 mph faster last year with cruising speeds approaching 28 mph. Now for the first half of this season, I've been "stuck" at about 26 mph max cruising speed. This is what I did last weekend at Waterford. I don't know what it is, as I've felt that I've trained just as hard as last year, and should be in the same shape. I don't know if I need to move my bottom bracket back again which will increase my frontal area, raise my shoulders etc.



Before I bought the M1 from John I made him a deal that I would consider buying it if I could beat my old time for 20K on this course with my Challenge. I CRUSHED my old record (27:40) by TWO MINUTES (25:40) the first time I rode John's bike, and it wasn't even setup right for me. I couldn't believe it. I had just nearly equaled the State Championship winning time by a Category 1-2 rider on an upright. I had rode about the same 27 minute time in the State championships the week before.
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Speedbiker
human power expert

USA
2467 Posts

Posted - 05/27/2012 :  11:21:13  Show Profile  Reply with Quote
Mike, your M1 is faster because it is a Ferrari and your Fujin is a 68 Camaro. I do not believe it is because flow is reattaching to your stays and improving pressure recovery so substantually that it increases your speed. It simply has much better body position and streamlining, as your picture shows. Years ago people wanted to say those little M5 tailboxes made them faster. I asked that anyvody who had one do coastdowns with and without to crudely prove decreased drag. As far as I know nobody ever proved that TF effective within measurable limits. And the M5 TF has a much better chance than fat stays begind your shoulders, no matter how slick they look. Drag reduction through improved pressure recover is VERY difficult. Remember Kammtail theory. It pretty much proves that decreased drag through improved pressure recover of super difficult. Basically, what's behind you is behind you. About the only way to reduce drag on a nonfaired recumbent is to minimize frontal area and turbulence(streamlining). Just ask Aure...
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mhelander
recumbent enthusiast

Finland
352 Posts

Posted - 05/27/2012 :  14:11:24  Show Profile  Reply with Quote
I've studied Mike's and others lowracer pictures in detail a lot prior to purchasing M5 lowracer, and after.

I really like JohnM design of handlebar to get hands out from flapping in sides. Also body is nicely reclined and legs when extended are in good horizontal position overall.

When riding any bent seriously frame construction and its stiffness should not be forgotten either. Especially if engine doesn't rev high and/or likes to use long cranks.

What I don't "buy" until really proofed, is frame fairing and putting rider as low to ground as in NoCom. Maybe it's my thinking of overall practicality and risks management.

You can see my results, although partially, tuning my M5 lowracer to enable as aero efficient riding position in my recent pictures. Today was 1st day to ride in summer clothes, and instantly was evident that this ride is faster than last summer. Engine will get high-rev treatment gradually and do that with relatively long cranks (172.5 for short-legged 180 cm rider).

Mike, your 41 km in hour is really good time. I've just broken my 41 kph in 10 km TT... is this hour record done in road or track ? All my stuff happens in road courses.

Cheers,
-Mika

MetaPhysic 700c @ 2011, M5 CrMo Lowracer @ 2010
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mhelander
recumbent enthusiast

Finland
352 Posts

Posted - 05/27/2012 :  14:16:03  Show Profile  Reply with Quote
And what I tried to say in previous, little long post, is that it's more about getting body position right, head & helmet and arms too. This has most potential to improve aero efficiency. Then comes height of BB and practicing to produce required power in that position.

Next is to improve wheels, like deep rim or disc to rear and deep rim and/or 3-spoke (or few radial spokes) or disc to front. And then to have race quality tires.

After all above is in order, might some benefits come from fairing the bike or having those chain stays this thread is subjecting.

Cheers,
-Mika

MetaPhysic 700c @ 2011, M5 CrMo Lowracer @ 2010
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Victor Ragusila
recumbent enthusiast

Canada
352 Posts

Posted - 05/27/2012 :  14:42:18  Show Profile  Reply with Quote
If the chainstays are able to re-attach even a big of the flow, it would be very beneficial, more so than aero wheels I believe. If anyone has a low racer without big chainstays, it would be neat to see if two pieces of carved foam around the chainstays would make or not a big improvement.
My guess is no, but that is just a guess.

Victor
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Speedbiker
human power expert

USA
2467 Posts

Posted - 05/27/2012 :  15:21:07  Show Profile  Reply with Quote
Yes Victor, if you were sitting more upright and your stays were shaped like a Razz Fazz tailfairing, they might help. Except when sailing in crosswinds, most every TF I have seen built gave only a very, very small increase in speed. And they have MUCH more area than two fat stays. And I have yet to see a tf make a noticeable improvement on a bike like a NoCom. Some nice ones have been made, so where are all the excited posts of big speed gains? I think most end up as exotic luggage boxes. So, I ask again, if a big, long, well crafted tailfairing doesn't speed you up measurably, what are fat stays going to do? Please, would someone believing fat stays speed you up explain how they do what something properly shaped and with 20 times the area can't?
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n/a
deleted

2373 Posts

Posted - 05/27/2012 :  19:44:40  Show Profile  Reply with Quote
Randy,
The stays on the NC provide upper torso support which locks the body in the seat and benefits power transfer. There is nothing more to it.

quote:
Originally posted by randy

I don't think it matters, the seat angle is too steep. Those stays are penny-wise pound-foolish (when considering unfaired hour-record bike design).

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purplepeopledesign
recumbent guru

Canada
585 Posts

Posted - 05/27/2012 :  19:52:44  Show Profile  Reply with Quote
Maybe we're considering too few parameters at one time. For example, there is overall surface drag. Maybe the TF re-attaches the flow much better than large chainstays, but not enough to overcome its additional surface area while the fat stays re-attach enough flow to be effective without significantly adding to the overall volume.

:)ensen.

Those who claim to be making history are often the same ones repeating it.

Video of my trike
http://www.youtube.com/watch?v=MdSLRD_2vzc
Photos of my trike
http://www.flickr.com/photos/purplepeople/
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Speedbiker
human power expert

USA
2467 Posts

Posted - 05/27/2012 :  21:06:30  Show Profile  Reply with Quote
If you look at NoCom stays, like I did mine, you will see that they curve AWAY from any potential airflow. In fact, there is a big lip around the back of the seat. I find it quite surprising anyone could think the air might pull "a magic loogie" and hook around, somehow maintaining enough energy to reattach itself, then flow backward and achieve positive pressure recovery to reduce drag. And now we should consider the fantasically minute effect of wetted area? Alan said it best, the stays brace your shoulders. End of story.
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purplepeopledesign
recumbent guru

Canada
585 Posts

Posted - 05/27/2012 :  21:41:13  Show Profile  Reply with Quote
So... what you're saying is that a metal framed monster with a riding position and frontal area to match the NoCom should have the same top speed?

:)ensen.

Those who claim to be making history are often the same ones repeating it.

Video of my trike
http://www.youtube.com/watch?v=MdSLRD_2vzc
Photos of my trike
http://www.flickr.com/photos/purplepeople/
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Upright Mike
human power expert

USA
3463 Posts

Posted - 05/27/2012 :  21:46:18  Show Profile  Visit Upright Mike's Homepage  Reply with Quote
I agree with Thom that the chainstays aren't big enough to reattach flow. None of this is based on any actual testing though with tufts. I heard that the Razz-Fazz did work well though, even though it seems bigger than some people's shoulders. My uneducated theory (I had to retake my fluid dynamics course in kollege) is that if a tailbox such as the Razz-Fazz is slightly bigger than a person's turbulent shoulders than it "reaches out and smooths out the flow", otherwise the wake behind a person's shoulders is just being dragged over the surface of a smaller tailbox.

If I ever have time this summer or next, in between racing and getting a streamliner ready for Battle Mountain, I'd like to build some foam tailbox shapes and even a body skirt as I show below. I'll leave my legs out. I think this SuperStreet raceer might be worth a few more mph in speed.

My Morciglio M1 lowracer has allowed me to go speeds I hadn't thought possible on an unfaired bicycle.
Mika - both the 41 and 44.5 kph averages for one hour are on a 6 mile (9.67 km) loop course with about 128 feet (39 meters) climbing / descent per lap. This is where I ride and train often. http://www.mapmyride.com/routes/view/4881966

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Speedbiker
human power expert

USA
2467 Posts

Posted - 05/27/2012 :  22:46:07  Show Profile  Reply with Quote
No Jensen. Go back and read my earlier posts. The NoCom and M1 streamline the airflow around the frame, wheels, and especially under the seat. I ride that tube frame monster, and race results show it is quite close to a NoCom in performance. I often win the stock class coastdown at the Mich hpv event. Nonfaired speed is about streamlining and body position. Ask Aure. No splitters or fat stays there! But, great body position and streamlining.

Right Mike! The huge Razz Fazz tf showed us that the shape needs to reach out to airflow that still has enough energy to reattach. A very tricky proposition!
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mhelander
recumbent enthusiast

Finland
352 Posts

Posted - 05/28/2012 :  02:02:46  Show Profile  Reply with Quote
quote:
Originally posted by Speedbiker

I ride that tube frame monster, and race results show it is quite close to a NoCom in performance. I often win the stock class coastdown at the Mich hpv event. Nonfaired speed is about streamlining and body position. Ask Aure. No splitters or fat stays there! But, great body position and streamlining.


That's exactly what I thought it to be. And, actually, counting on it as owner/rider/racer of M5 CrMo lowracer...

Have'd plan to build tail fairing. Haven't yet had enough reason to proceed with. First order is to get all other optimization done and engine into appropriate condition.

Cheers,
-Mika

MetaPhysic 700c @ 2011, M5 CrMo Lowracer @ 2010
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mhelander
recumbent enthusiast

Finland
352 Posts

Posted - 05/28/2012 :  02:24:09  Show Profile  Reply with Quote
quote:
Originally posted by Upright Mike

Mika - both the 41 and 44.5 kph averages for one hour are on a 6 mile (9.67 km) loop course with about 128 feet (39 meters) climbing / descent per lap. This is where I ride and train often. http://www.mapmyride.com/routes/view/4881966



Looks really nice lap, and quite comparable profile to ones I used to race:
Ylikiiminki 10km TT (my best 13:18 @ mid-90's)
Alakylš 10 km TT (more open to winds, not so fast course)

We have that 5 & 10 km TT with U-turns but don't have that mapped in Strava yet. That course is quite shielded from gusty winds and no much elevation... I found being faster in rolling road course than more flattish one. And my speed seems to be on par both in lowracer and MetaPhysic. It would be very interesting to see NoCom or its kind of lower bent to perform in courses familiar to me.

I've done in that Ylikiiminki course 40+ kph over 37 km's... but not yet when riding bent. Most likely ever (since -90's there is five stoplights added to this course and likely no races without stoplights to be organized).

Cheers,
-Mika

MetaPhysic 700c @ 2011, M5 CrMo Lowracer @ 2010
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ckaudio
recumbent enthusiast

117 Posts

Posted - 06/02/2012 :  19:11:42  Show Profile  Reply with Quote
At Rite Aid tonight I found that they had a whole shelf of chia pets. I bought 7 of them and think that there should be enough of the seeds and sticky solution to cover the entire nocom frame. I am going to apply it tomorrow night and then water it for the next few days. Within a week I should be able to do the ultimate tuft testing!!!! I'll keep you guys posted. I thought about doing it to a more worthy vehicle...(the quest) but that chia crap is expensive... and I could easily purchase another rear tire instead.
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Speedbiker
human power expert

USA
2467 Posts

Posted - 06/02/2012 :  19:20:03  Show Profile  Reply with Quote
Turf testing!
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sean costin
human power supergeek

Lesotho
1978 Posts

Posted - 06/04/2012 :  21:20:59  Show Profile  Reply with Quote
The Nocom has a confluence of 3 elements, the head rest, seat back and stays which are efficiently webbed together in a concave triangular shape of one structure that was also efficient for creating the bonded areas necessary to combine the sections of the bike in the assembly process. The stays are as short as possible for this size of wheel. the seat is reasonably sized to the body and considerably smaller than my back. The neck rest is a properly sized to distribute the load to my neck.

I think in some pictures this area looks to people like a big blob that has more meat to it than it really has. I think this is mostly due to the way the head rest sweeps back very tightly to the rear wheel. The black of the carbon masks the curves somewhat. Here are some pictures I took a few years ago that might illustrate things better.

On the first picture, notice where the dropouts are in relation to everything else. The seat only exists a couple inches wider than the dropout width which are themselves very skinny. Most of the structure is within the width of the dropouts.

All of the parts are structurally necessary.

I would estimate that the horizontal area of the stays are about 2" below my shoulders in that area.

The head rest must be supported and the supports cleverly shroud the rear wheel. The head rest structure is necessary, no wider than other frame elements and could be considered a splitter. The structure is completely shrouded from view when the rider is viewed from the front.

Does it attempt to re-attach flow behind the rider. No.
Does it re-attach flow inadvertently? no. I have done tuft testing and found that against head rest support area, the airflow was upward. So was the area under the seat. The mid upper section of the stay was very turbulent as well as a tuft near the dropout. I had some video, but have not been able to find it. I'll see if I can do it next time I go to the velodrome with my I phone taped to my helmet.

Why is this a fast bike despite the relatively upright head position? I think it is due to reduction in drag from the rear wheel acting as a splitter and reducing the vortex street behind the rider. Flow does not become re-attached to anything. As we discussed and approved the WRRA rules, my thought was that one would need to build a structure that would bow outward from the body to re-attach flow.

I had planned on a more restrictive set of rules, but the consensus was to keep things as simple as possible. We may need to create definitions of the words used in the class description as some people seem to be interpreting their meanings differently than I believe we intended when we drafted the rules.

I have never voted to approve any of my own attempts on the Nocom.


Sean




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Runxner
recumbent enthusiast

USA
336 Posts

Posted - 06/05/2012 :  03:30:17  Show Profile  Reply with Quote
Didn't Alan chop the stays off his m1 and not see a speed differece?
http://recumbents.com/forums/topic.asp?TOPIC_ID=3693&whichpage=1&SearchTerms=wunderbike


Team Low-Life
Lowracer Test Pilot/Evangelist
Adelaide, Australia

Edited by - Runxner on 06/05/2012 03:30:42
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