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Old 02-06-2022, 09:18 PM   #31 (permalink)
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Quote:
Angles: here You see...

As You might see here...
???

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Old 02-08-2022, 02:11 PM   #32 (permalink)
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Obviously i forgot to link the image:



I am currently cleaning up the ribs. The lower most one will serve as the reference. The shape of upper two will need to be corrected. These end up in ~15 angles. The topmost rib is the one with the 22 angle. That one will problably need to renewed: the distance to the end enlarged again in order to obtain a smaller angle, and the tip lowered by roughly 2-3 cm so that the plane will be horizontal or even pointing slightly downward. That alone for optical reasons, but will it also improve the aerodynamics as long as the top rib is also the top of the box?



I also consider to make the box narrower by 2-4 mm at thejoint with the body of the velomobile. Again - initially it has been narrower by 8-10mm on each side - here the 1st version before the tests - that one turned out to be too narrow for the movement of the back wheel :-(

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Old 02-08-2022, 03:05 PM   #33 (permalink)
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Looking at #17, I wonder if the flexure is side-to-side or twisting.

The two possibilities I see are truncating the shell at the axle line and letting the wheel protrude, or adding skirts to the arm that would both stiffen it and clean things up around the derailleur.

I also wonder if adding a countermass ahead of the pivot point would act as a harmonic damper and affect the ride. ....but that's another matter.

edit:
It's hard to decide. If you take a tangent further forward, add a scoop at the top, pivot the entire tailbox, and use a 4-bar linkage to counteract the wheel, then you might get the best effect. It would need additional clearance for wheel hop, but weight at the back would be on a long lever arm.
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Old 02-08-2022, 03:25 PM   #34 (permalink)
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Quote:
Originally Posted by freebeard View Post
Looking at #17, I wonder if the flexure is side-to-side or twisting.
It seems to be mostly twisting.

Quote:
The two possibilities I see are truncating the shell at the axle line and letting the wheel protrude,
Which is what i did and now would like to improve. Learning more on some details ist the main intention of this thread.

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or adding skirts to the arm that would both stiffen it and clean things up around the derailleur.
The arms have already been stiffened, but not against torsion. I'm going to renew the during the year.

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I also wonder if adding a countermass ahead of the pivot point would act as a harmonic damper and affect the ride. ....but that's another matter.
No need for any effort - despite the stiffness issues it rides pretty well. Body stiffness is in general a big topic with most of the old velomobiles, and it pretty difficult to improve it without adding too much weight.
You actually need to compensate by removing mass wherever possible (there are some fairly easy possibilities: pedals, back wheel, back suspension strut have already been done, remaining: seat and a little bit of work on the front suspension is still in the pipeline.)
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Old 02-08-2022, 05:18 PM   #35 (permalink)
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Quote:
It seems to be mostly twisting...
The arms have already been stiffened, but not against torsion. I'm going to renew the during the year.
No picture so far shows any attachment point above the swing arm pivot. Is there an upper connection or is it all in torsion at the pivot?
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Old 02-08-2022, 07:36 PM   #36 (permalink)
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There is all torsion at the pivot.

BTW: construction like that can well made to be stable. Simplest approach: thickening the arms.
Then: use CFK.

Like here - latest successor of my bike , the Evo-R which is one of the really light, stiff and fast machines:


And here my 1st test with wood (spruce). Noticeable improvement, but torsion remains. Which tells me how large the effect of torion in the arms really is.


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Old 02-08-2022, 08:59 PM   #37 (permalink)
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That concave sill narrows the body to no avail. The axle is held in the middle instead of the outer ends.
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Old 02-21-2022, 07:18 PM   #38 (permalink)
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Closing the back with stripes of Paulownia wood

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Old 02-26-2022, 09:02 PM   #39 (permalink)
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Finally the tail mounted to the velomobile



here the parts of the tail i consider most problematic, especially the central area:

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Old 02-26-2022, 09:40 PM   #40 (permalink)
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Thanks. I was wondering today how you're doing.

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