86.65mph

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Stradageek
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86.65mph

Postby Stradageek » 21 Sep 2015, 1:09pm


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[XAP]Bob
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Re: 86.65mph

Postby [XAP]Bob » 21 Sep 2015, 4:24pm

Awesome...
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
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Brucey
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Re: 86.65mph

Postby Brucey » 21 Sep 2015, 5:17pm

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Nice design; big wheels, reasonably efficient transmission, good aero packaging. Making the machine with a removable fairing means that in competition, one rider can throw it down the road and you can be up and running again without great delay. It also means that all kinds of shakedown work can be done without the fairing; this means there is no need to build a 'mule chassis' to trial the systems etc; it can all be done on the final chassis.

If I am critical I'd say that the machine width is greater than it needs to be near the front, mainly because the front wheel clearance for steering means the cranks are further apart than they might otherwise be. This has knock-ons for the pressure gradients at the front of the machine as does the external spaceframe at the rear. In a crosswind the flow is maybe going to detach a bit sooner than it might otherwise. In still air with a perfectly clean fairing neither thing is going to be a real issue.

86.65mph? That is a high bar. Congrats to the aerovelo team.... I note that VeloxV didn't perform that well, I think they have maybe lost sight of the fundamentals with the design they made for this year. Liverpool Uni's Arion1 did OK, (75.03mph is a new UK record!) I wonder what they will do for next year?
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Now all we need is something as slippery as that for nipping down the shops in.... :wink:

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[XAP]Bob
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Re: 86.65mph

Postby [XAP]Bob » 21 Sep 2015, 8:49pm

They all seem to have camera stalks now - a couple of years ago they had air intakes at the front, to feed cool, oxygenated, air to the driver - but now they don't - I'd have thought that the nose cone would have been the place for the camera, rather than yet another aero drag device.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

Brucey
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Re: 86.65mph

Postby Brucey » 21 Sep 2015, 9:50pm

when Delft first did it they said the pod gave them +0.5% drag vs a perfect shell, but that they couldn't make a window that was good enough, aerodynamically speaking, so the pod was a better idea overall. I wonder if they were really trying, or if the stated requirement for a 3D curve over the window was really strictly necessary after all.

I think the camera position is such that you get a view from high up that includes the machine, so you can see exactly where you are pointed; I think such a view might suit the 'video game generation' rather well. Having the camera at the front stagnation point of the machine wouldn't give such a good view, I'd have said.

The runs are done over a flying 200m, so for that purpose, cooling is something you need after the run, not 'during' in the same way as in longer events.

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[XAP]Bob
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Re: 86.65mph

Postby [XAP]Bob » 21 Sep 2015, 9:54pm

Takes a little while to get to that 200m though - although maybe the vents were in an hour record version?

Given the effort they went to on the wheels it just seemed odd to make a little stalk, although the keyword there is little - it's probably not a huge contributor
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

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RickH
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Re: 86.65mph

Postby RickH » 23 Sep 2015, 4:06pm

Just as well he didn't exceed 88 mph! :D


Geoff.D
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Re: 86.65mph

Postby Geoff.D » 24 Sep 2015, 8:44pm

Brucey wrote:I think the camera position is such that you get a view from high up that includes the machine, so you can see exactly where you are pointed;


This rings true with me.

I'm thinking of a recent discussion about how a bike stays upright ( viewtopic.php?f=1&t=100023 ). It was clear that at this sort of speed an upright bike with "normal" steering geometry would stay upright by itself. But this machine may have different characteristics. It's possible that being able to see the machine's attitude relative to the ground may help the rider (driver?) to balance it if needed, (as well as/through steering).

They may be minute inputs from the rider, but may be crucial.

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Re: 86.65mph

Postby Brucey » 24 Sep 2015, 9:00pm

in conditions where there is no peripheral vision input, I guess you need every visual cue that you can get.

I note that at 86mph, if you are two degrees off line, you will be moving sideways on the road at nearly 1.5m/s. This means that you can be somewhere near the middle of the road, and two or three seconds later you can be off the road and having an accident.

None of these machines steer very well, often for multiple reasons. This year's Velox, VeloxV, was crashed at high speed and rolled over four times, and the Arion1 machine didn't ever look like it was going in a straight line either, I am told.

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pjclinch
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Re: 86.65mph

Postby pjclinch » 25 Sep 2015, 8:54am

Geoff.D wrote:I'm thinking of a recent discussion about how a bike stays upright ( viewtopic.php?f=1&t=100023 ). It was clear that at this sort of speed an upright bike with "normal" steering geometry would stay upright by itself. But this machine may have different characteristics. It's possible that being able to see the machine's attitude relative to the ground may help the rider (driver?) to balance it if needed, (as well as/through steering).

They may be minute inputs from the rider, but may be crucial.


A few years back Rob English was piloting the Kingcycle Mango going for the record. IIRC it was remarkably small and had very little trail and was reportedly something of a beast to keep upright...



I imagine that may have had some feed in to subsequent designs from all parties!

Pete.
Often seen riding a bike around Dundee...

Brucey
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Re: 86.65mph

Postby Brucey » 25 Sep 2015, 9:07pm

you can see why having an abrasion-resistant shell is a good idea!

I think this year VeloxV crashed and rolled over four times or something; potentially very nasty.

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bobc
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Re: 86.65mph

Postby bobc » 25 Sep 2015, 11:50pm

I'm assuming this is battle mountain again. IIRC it's a 5 mile run up to the 200m measured flying "speed trap", so actually plenty of time to get hot & tired...
86.65mph is astonishing isn't it. I believe the course is slightly downhill (the "speed record" rulebook seems to have been written to describe this place) and they don't have to average opposite direction runs like the car records, even so it really can't be easy balancing things like that at those speeds - especially when you're not striving your heart out!

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[XAP]Bob
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Re: 86.65mph

Postby [XAP]Bob » 26 Sep 2015, 7:06am

Someone went on a long tour of the US with a GPS to find the road after the rules were made. There is a very small gradient,
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

Brucey
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Re: 86.65mph

Postby Brucey » 30 Sep 2015, 10:05pm

bobc wrote:I'm assuming this is battle mountain again. IIRC it's a 5 mile run up to the 200m measured flying "speed trap", so actually plenty of time to get hot & tired...
86.65mph is astonishing isn't it. I believe the course is slightly downhill (the "speed record" rulebook seems to have been written to describe this place) and they don't have to average opposite direction runs like the car records, even so it really can't be easy balancing things like that at those speeds - especially when you're not striving your heart out!


I think they have both 2.5 and 5mile courses. I also think it is non-trivial getting the timing of the effort right; I suspect that the idea is to sprint (fully anaerobic effort, maybe ~ 1kW) for the last few hundred metres, having wound up to as high a speed as possible using aerobic capacity (about half that, I guess). A record breaking run could average ~50mph in which case five miles is going to take about six minutes or so. I think this is more than long enough to get into a complete state but not long enough that you are going to overheat too badly; on the rollers it takes me ten minutes @ several hundred watts before I break sweat much.

I also think it is worth noting that the kinetic energy is considerable (as is evident in a crash). If you had a bike that weighed about 20kg and got it up to 20mph, that'd be hard work. But that is one sixteenth of the KE of the thing when you are doing 80mph, and of course the drag is going up all the time the faster you go, so the surplus thrust available to generate more speed becomes smaller and smaller the faster you go. The last few mph must be an agonising effort.

I think the Arion1 team have posted some videos of their runs/prangs etc too. Not seen them yet.

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notme2
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Re: 86.65mph

Postby notme2 » 1 Oct 2015, 8:07am