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warren
human power expert

USA
6351 Posts

Posted - 02/23/2018 :  08:01:32  Show Profile  Visit warren's Homepage  Reply with Quote
I may have missed this but why is there so much space between the seat back and the rear wheel? Storage? Batteries? Dog seat? Taller riders?

Also you are adding some triangulation to those rear stays, right? Those butt welds will fail eventually.
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Matthew Martin
New Member

USA
56 Posts

Posted - 02/23/2018 :  16:02:10  Show Profile  Reply with Quote
The reason that there is so much space is mostly for storage. As I stated long ago I need it to fit my skateboard and book bag, and to do this I had to make the shape of the body longer. I figured that I might as well move the wheel farther back the help with wind stability. The wheel farther back will also allow for larger riders.




Thank you for pointing that out!. I currently can't do anything to triangulate, as I need to get more tubing, so I am open to suggestion, however this is my current solution.


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warren
human power expert

USA
6351 Posts

Posted - 02/25/2018 :  09:13:19  Show Profile  Visit warren's Homepage  Reply with Quote
That should work fine and also provide some passive suspension.
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carolina
recumbent guru

USA
942 Posts

Posted - 02/25/2018 :  09:35:11  Show Profile  Visit carolina's Homepage  Reply with Quote
Can u show frt & rear seat mount. I have used 2 choices. Then one on my lowracer (df / quest velo hardware), and in my velomobiel (WAW/ & Quest hardware). My favorite seat hardware is DF. Df and quest use lightest seat on earth because of their hardware that holds seat. Your building a velomobiel per definition. I have studied velomobiels for 4 years daily. Study Daniel fenn for weight savings.

Some definitions:
go back to definition of velomobile: it provides aerodynamic advantage, weather protection, human powered. (Even though i think a trike with a shell is a trike with a shell). The modern unibody can be your second build.
-
velosRus.com

Edited by - carolina on 02/25/2018 09:40:22
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alevand
human power expert

USA
3309 Posts

Posted - 02/25/2018 :  19:13:49  Show Profile  Visit alevand's Homepage  Reply with Quote
Watch for interferences in the chain line and frame.

C:
Tony Levand
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Matthew Martin
New Member

USA
56 Posts

Posted - 02/25/2018 :  20:33:06  Show Profile  Reply with Quote
Here are pics of the front mount and rear mount.





The pictures on the previous page shows how the seat it mounted. I am not concerned about weight right now, rather I just want to get a moving bike. I will work on weight later.

And Alevand, I am using chain management pulleys to keep the chain below the frame rather than across the frame.
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Matthew Martin
New Member

USA
56 Posts

Posted - 03/02/2018 :  20:32:33  Show Profile  Reply with Quote
I rolled down the driveway!

I got the linkage set up using conduit, which I de-galvanized using muriatic acid. This is only a temporary solution and will upgrade later, but should work even when I put the cranks on. I have to order 2 more idlers for the chain management.
The steering tube is simply 2 washers and a bolt though them. This creates a lot of slop. I have bearings which can be pressed in however I cant find the proper 15mm bolt to fit the bore on the bearing anywhere online.



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alevand
human power expert

USA
3309 Posts

Posted - 03/04/2018 :  08:06:11  Show Profile  Visit alevand's Homepage  Reply with Quote
That's progress. Steering looks unrestricted. You'll need landing gear or a kickstand to get in and out of the fairing through the top, or a side door, you wont be able to stand up with the bars that far back. I have used the same ace hardware wheel barrow bearings for steering and tack them in the same way. I split the tube lengthwise and welded it back for a tight fit. I used 4130 tubing for the spindle instead of a solid 15 mm bolt, welded into a T, well more like and arrow head. If you angle the bars down, its more comfortable to ride. You might have some interference with the right brake and pivot, I like to push the brakes as far inboard as possible, so they don't contact the fairing. I have made a second stub just for the pivot. You can run the front brake cable along the linkage. I make the remote pivot a little further outboard than the fork end, as space is tight for turning in the fairing. I've always attached the pivot to the fork crown, because the front of the fairing was lower, you might have trouble seeing the road in front of the bike. Id recommend not using HCL for zinc removal, as a whiff of the fumes will destroy your sense of smell permanently (my experience, I cant smell a thing).

C:
Tony Levand

Edited by - alevand on 03/04/2018 08:12:42
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Matthew Martin
New Member

USA
56 Posts

Posted - 03/06/2018 :  17:51:58  Show Profile  Reply with Quote
by unrestricted do you mean no steering limiter? I do plan to implement one later on. Thanks for the advice... I use the muriatic acid with a respirator outside, and don't stick around as soon as I insert my piece.
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Matthew Martin
New Member

USA
56 Posts

Posted - 03/31/2018 :  12:59:14  Show Profile  Reply with Quote
Well I have done some more work and have made all the main components, like the BB clamp and handle bars. I could have had it ride able but decided to change the design (Shorter).
The BB clap with the Tiagra crankset



The handle bar


Cutting up the frame


New design

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Speedbiker
human power expert

USA
3835 Posts

Posted - 03/31/2018 :  22:44:40  Show Profile  Reply with Quote
Good job, Matthew. I love the shorter design. Keep up the great work.
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Matthew Martin
New Member

USA
56 Posts

Posted - 04/14/2018 :  19:39:19  Show Profile  Reply with Quote
A lot has happened since the last post...

About three weeks ago I started to work on the new design and I cut the frame and welded the new tube



All was good I the welded in the chain stays and dropouts


Then after some rides down the drive way I noticed quite a bit of flex.. I expected this as I had not added any triangulation yet, however what I did not know was that the flex was actualy tube failing.



After being extremely frustrated I got to work, I managed to salvage the chain stays and dropouts so that the new tube rest insite of the old tube like a jacket.



I then worked on adding some triagulation. I did this in a way that I do not like to do things, which is with out any plans. I simply took a few measurements and decided if it looked good or not.







The results came out great, the frame is stiff , but heavy
mind the chair in the back...I was fixing them for neighbors.









Now I am just working on the pulley mount!
I will re make the steering linkage later with some smaller tubing that is not conduit.

Edited by - Matthew Martin on 04/14/2018 20:39:37
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warren
human power expert

USA
6351 Posts

Posted - 04/15/2018 :  09:25:10  Show Profile  Visit warren's Homepage  Reply with Quote
That's much better! Is there any way you can bring the front wheel closer to the cranks without having your feet hit it?
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Matthew Martin
New Member

USA
56 Posts

Posted - 04/15/2018 :  12:48:59  Show Profile  Reply with Quote
I could right now, but I want the cranks to have room to slide up for taller riders, so when I grow I wont have to remake the frame.



the shapes represent the amount of space that a foot needs when pedaling. I don't want much heel overlap when the BB is in the farthest position.
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Matthew Martin
New Member

USA
56 Posts

Posted - 04/20/2018 :  21:06:45  Show Profile  Reply with Quote
Since the last post, it was suggested that I place another tube behind the seat. I worked through a couple of iterations before settling on this one.





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teubner
recumbent guru

803 Posts

Posted - 05/20/2018 :  01:00:11  Show Profile  Reply with Quote
Other than BM, I've been away from this forum for years, and landed on this thread by accident while searching for a Rotator Pursuit. I feel like I've been down some of the roads discussed here. Gave up on a streamlined 2-wheeler after getting blown over in a race.

Matthew, remember that it isn't trivial to make a compound curve that is optically clear. Your shell design should allow for a windshield formed from a simple curve of a flat piece.

My personal opinion is that you don't want a windshield on a daily commuter. It will get dirty in the parking lot and you won't have a good way to clear the dirt without scratching it. And I have been unable to keep a windshield from fogging, but I live in a much colder climate.

Having said all that, you are impressive. Keep on...
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carolina
recumbent guru

USA
942 Posts

Posted - 07/22/2018 :  15:42:41  Show Profile  Visit carolina's Homepage  Reply with Quote
Give me some update matthew. To many hot chicks? Huh?

velosRus.com
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Matthew Martin
New Member

USA
56 Posts

Posted - 10/03/2018 :  19:14:38  Show Profile  Reply with Quote
HaHa I wish...
Well long story short, I simply took break earlier this year for exams and school related business and was planning to resume as soon as the summer began. Well I never picked it back up over the summer (physical work).

I believe this is a good thing. Though I have not made any progress (physically) in the past 5 months, I have made some considerations.
For starters, you guys were right, a faired bike is no good on the road. I also realized that I want a fast bike
What I was planning to do would not only give me a reasonably aerodynamic bike, but one that is not very rideable on the street and has low visibility
In addition, the CFD software that I was using before was extremely lacking in just about every aspect. I have since began using Simscale, which runs open foam simulations, and Paraveiw to analyze each iteration.
Essentially, I am starting over with some new goals
1
Build a Speed Bike. This will be a fast-impractical bike. Large turning radius, low to the ground and most likely short wheel base. This bike would be for closed courses.
2
I have since learned a lot more about aerodynamics. My new fairing will be based on a Naca 6 series aero foils to get a better pressure
3
The geometry that I am using is based off a 6ft2in-6ft3in individual (average proportions) based on Anthropometric data that I found online.
4
Uses mostly standard road bike parts (Standard cranks and group set). This was a challenge as most cranks have a q factor of 150 and a 170mm length. Also uses a 700 c rear wheel just because they are easier to find and more tires are available.
5
Uses a removable subframe. This is to enable me to replace it later with a better design or lighter materials. I also want to use square tubes instead of round ones.

Those were just some of the main goals for now. In previous posts I have explicitly stated that I want a road machine, and that I do. I plan to do this by eventually building a trike based off the fairing that I build. But that is later, and I will be focused on the bike right now
If/ When I get to the trike, it would probably be like Aerovelos Arbiter concept, but let me not get ahead of myself.
Though I have wasted precious time I think it may have been for the better. I apologize for not responding sooner. I wanted too but did not know how to explain, but now that I have a little something to show for, I think it will make sense.

Now my most recent iteration:

It has a Cda of .0215 @ 31.3m/s which is about 70mph
At 13.9 m/s (30 mph) it has a Cda of .0303
It has a very nice pressure distribution as well:


And lastly the new geometery:


I welcome critiques and criticism


Edited by - Matthew Martin on 10/04/2018 05:20:27
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Balor
recumbent guru

Russia
656 Posts

Posted - 10/04/2018 :  02:37:24  Show Profile  Reply with Quote
Why not Valkyrie instead? A leaning delta trike with tilt lock seems much easier, fast enough and yet practicable enough.
You don't have a budget of an entire team after all...
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Balor
recumbent guru

Russia
656 Posts

Posted - 10/04/2018 :  03:04:34  Show Profile  Reply with Quote
By the way, can you provide any pointers for setting up virtual wind tunnel using Simscale, and finding out total CdA and drag on your model in particular?
I've also been using a very 'lacking' CFD (FlowDesign) that seem to do a VERY poor job of modelling even relatively simple stuff like CdA value of deeply concave surfaces - I'm trying to analyse how much benefit I'll getting from a nose cone (front fairing only) and getting WAY unrealistic predictions (cutting drag by half at the very least)
I'm tried to validate those results using a 3D printed model in, ehehe, bathtub and found out that my fairing actually adds to drag instead, which makes me vary to continue.
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alevand
human power expert

USA
3309 Posts

Posted - 10/04/2018 :  07:28:24  Show Profile  Visit alevand's Homepage  Reply with Quote
Well its been a long time, welcome back Matthew.

Your latest idea is close to Warren's Barracuda (W), He's 6'-5", I think, or Seans's Swift bike. You might want to check out his projects pages, http://www.recumbents.com/wisil/whatsup.htm#top

Speed bikes usually tolerate some crank overlap with the front wheel, if you don't intend it for road use, as most of the steering is used only at starting, once you get rolling and pull up the landing gear only a few degrees is needed to get around traffic on the track.

Front wheel drive saves a pound of chain and allows for a lower seat height. A suspension is very nice to have on a SWB, but is trickier with FWD. With the long inseam, maybe consider a larger front wheel to reduce rolling resistance and improve ride. Velodromes and race tracks are not real smooth, some have jarring cracks in the pavement.

C:
Tony Levand
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Balor
recumbent guru

Russia
656 Posts

Posted - 10/04/2018 :  08:21:22  Show Profile  Reply with Quote
By the way, I've found a nice high-res picture of Valkyrie tilting assembly:



Still, it would not provide passive stability at all speeds and conditions, and should be considered as an elaborate 'landing gear' first and foremost. For it to provide suspension as well it would have to be made way more complex... that is why their 'practicable' goal is a tadpole after all.

By the way, as I understand from perusing the articles and my own experience with different bents, low lateral CP is extremely important for side wind stability... but what is more important is having CG as HIGH as possible (reverse of what you'll want on a trike).
The higher your CG relative to your CP, the less you need to lean into the wind (hence turning yourself into airfoil and generating lift that, once it overcomes your weight, will cause you to 'take flight'... good if you are an aeroplane, not really for a streamliner :)) and wider time window for balance corrections - which I think goes against conventional wisdom (maybe for a good reason, so take this with a pinch of salt).

It also gets you out of ground effect, but without wheel fairings of some sort (that add a LOT to your side area due to being nearly flat.. tri or better yet, two-spoke wheels might help) it would generate extra drag.
Those considerations are important even for an 'impracticable' streamliner, some race days might be windy I think.

Edited by - Balor on 10/04/2018 08:23:17
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warren
human power expert

USA
6351 Posts

Posted - 10/04/2018 :  11:13:19  Show Profile  Visit warren's Homepage  Reply with Quote
I have to agree with your logic Matthew. You will be much happier with a fast unfaired recumbent. IMO the dual 700C bent frame platform with a reasonably laid back seat seems to be the best compromise for speed and practicality. You can add a rigid tailbox/panniers to that to allow you to carry stuff.

Also your new fairing design looks very fast!
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Matthew Martin
New Member

USA
56 Posts

Posted - 10/04/2018 :  19:51:54  Show Profile  Reply with Quote
Oh, I am nowhere near 6ft, I just want the fairing to have extra clearance. The current model uses 170mm cranks, which are a challenge to work around, But I want to use as many readily available parts as possible, plus I already bought a new group set.
I dont want to have a Fwd set up as I like the simplicity of a Rwd setup, though it is less efficient and heavier. Plus once again I want to use as many readily available parts such as a rear road 700c wheel. I can always change later because of the extra space I have built into the design.

For now I will be designing the frame. I will use the geometry below and a 20in front wheel. x seam will be able to range from 95cm-115cm or more if more narrow cranks were used.
The subframes will probably mount on to 2 aluminium tubes first, then once I actually build the fairing, I can mount it in there, similar to how they prototyped the Velotilt.

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Balor
recumbent guru

Russia
656 Posts

Posted - 10/05/2018 :  04:45:42  Show Profile  Reply with Quote
You *really* want shorter cranks for aero. I don't think mine 140mm ones cost me much (if at all) power, but it makes making fairings of reasonable size MUCH easier. Better cockpict ergonomics as well, but it depends on what you have I guess.

There are sources of shortened crank if you want a good one (Sram Rival), but you can buy square taper BMX race cranks really cheaply and down to 120mm.
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