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Furloughed aerodynamicists - Battle Mountain bike
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russellbridge View Drop Down
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    Posted: 26 March 2020 at 7:58pm
I've been thinking about how BHPC might find some positives out of the current lockdown situation, and I'm wondering if there are any furloughed aerodynamicists out there seeking something meaty to occupy their minds?

If there is anyone looking for a challenge, how about getting some big brains (and CFD?) together to have a proper think about how Todd Reichert's 89mph may be significantly improved by a UK team with a decent athlete on board?

Geoff - how is the situation in vehicle design world at the moment - are people being furlonged? Does anyone else know anyone who might be interested?  Anyone know any BAE / Airbus / F1 staff or similar who might be interested?

I'm starting to read John D Anderson's 'Fundamentals of Aerodynamics', but these are baby steps for me...

Russ

For anyone interested, a couple of primers are:

Matt Weavers speed 101 website, now taken down but available through the Wayback Machine: https://web.archive.org/web/20070905182534/http://www.speed101.com/ 
Matt's essay which starts half way down this page is still ahead of most team's current thinking (starts half way down at The "Virtual Edge" - Technical Notes) https://web.archive.org/web/20130429112301/http://www.speed101.com/words.htm#WordsAmazingBicycle

Aerovelo's videos on YouTube: https://www.youtube.com/channel/UCaaBYl_LnxAecUOgfVTQHvg/videos  - this one in particular gives a good overview: https://www.youtube.com/watch?v=BC5KIFHd5Ao






Edited by AlanGoodman - 27 March 2020 at 9:26pm
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AlanGoodman View Drop Down
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Points: 8036 		Post Options Post Options   Thanks (0) Thanks(0)   Quote AlanGoodman Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2020 at 10:16pm
Graham Sparey Taylor may be worth a shout...

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Without active manipulation of boundary layer like boundary layer suction (that had stumped multi-billion corporations and the military) laminar boundary layer is NOT good because, as much as I understand, it will preclude pressure recovery because it will 'fly away' upon meeting adverse pressure gradient pretty much instantly and it will result in more drag.

It should be possible in theory to have a human-powered pump for that purpose, and some problems that made BRL unviable for planes (icing, for instance) are not a problem for a HPV in a desert.

Dust, bugs, most importantly, *vibrations* and shell 'swaying' due to pedalling will kill laminar flow anyway, however.

As far as I understand, Eta has 'laminar' part of shell on vibration isolators. It might be possible to have the shell inherntly vibration isolating/dampening by making it of dampening material, or a composite with dampening interlayers.

For best effect, you should have the shell completely isolated from the body using actuators to cancer out vibrations and bike motion. They would have to be human-powered as well however.
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I agree with Balor on this.
 
Just ignoring aerodynamic losses for the moment. I have noticed when riding my Bachetta on long rides (~100miles) with other road bikes that I was faster on downhill or smooth flat bits of road. I was probably slow on uphill because of weak power in the recumbent position (my area is very flat). But the interesting one was why I was *much* slower on flat rough road. My guess this is due to mechanical losses rocking the bike back and forth whereas the upright rider pivots on the pedals and the riders body is not rocked back and forth.
 
Now with a fairing on Balor is probably right that rocking causes aerodynamic losses to also increase. It certainly increases the mechanical losses in my experience. I also like Balor's experiment with jockey wheels as a way to reduce this rocking, and human powered mechanical activators could remove the losses caused by a bad road. Not sure how bad the track is in Battle Mountain. Russ would you say that vibration from a rough road was serious at Battle Mountain?
 
 
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Russ this is a great initiative. I would be keen to join in but my expertise is low and restricted to aerodynamic indicators at the moment. The Mrs has had good experience setting up a Language teaching resource using workspace. Maybe this would be something to use a collaborative website that supported the sharing of documents, videos etc. Also video conferencing using e.g. Zoom seems very popular right now during the current lockdown.
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Hi Brian, slightly off topic but could you tell me want size chainring you had on your EVO-K?

Thanks.
Roy
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Hi Roy,
 
This is what my records say:
single chain ring 70T plus hand shift 39T
 
I will double check on the actual machine tonight and confirm.
 
Regards
 
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Originally posted by atlas_shrugged atlas_shrugged wrote:

Hi Roy,
 
This is what my records say:
single chain ring 70T plus hand shift 39T
 
I will double check on the actual machine tonight and confirm.
 
Regards
 

Thanks Brian. That's brilliant. It ties up with my thoughts almost. I settled on a single 74t in my After 7. I figure as my strength comes back post stroke I can always fit a bigger one in the future as and when it is needed. Wink
All the best.
Roy
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You mean using a bogie?

I don't think that's quite viable for a streamliner.

It *is* a good suspension, but it does have limitations - it *halves* bump size, and don't have problem with bob/roll or need any damping, but very a good suspension or, better, yet, a powered vibration-cancelling setup can eliminate bumps almost completely.

A 'rocker bogie' setup like on a martian rover and one I'm seriously contemplating using will half the bumps once and than half them yet again... but that's like 4 extra wheels :)

Anyway, no suspension can deal with vibration (very low pressure and fat tires.... maybe) in full. Electromechanical setup can, theoretically and might help keeping flow laminar longer, but it *will* get tripped eventually unless you suck out the turbulent and low-speed low portion - that should allow you to keep it attached indefinitely, too.

But this stuff is hellishly complex.
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Originally posted by Balor Balor wrote:

But this stuff is hellishly complex.

That's why I think we need professional aerodynamicists and vehicle designers involved rather than amateurs/students who've only been doing it a year or two, and are guessing at concepts rather than coming from 1000's of hours of experience (not that new thinking cannot produce great results)

Can I ask what you do for a living Balor - you seem to know your stuff!

I think the red dots on the image below (of ETA) are foam for 'shell isolation', and I recall from speaking to Calvin that the front fork has an elastomer damper in the headtube, all for the purpose of isolating the shell from the road vibrations.

Ah, I don't seem to be able to upload images today - I'll see if I can link to it instead:

Nope, that's not working either - clicky link here hopefully: https://jnyyz.files.wordpress.com/2016/08/dsc09263.jpg?w=584


Edited by russellbridge - 28 March 2020 at 5:17pm
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