Re: Genesis results

[ianpegram]

Hi All
 
Have just received my wind tunnel results from Southampton University, and  
no big suprises;
The basic shape is stable at all speeds up to 100+mph and there is a very  
small amount of negative lift at speed.
 
When we had finished the tests we ran the tunnel at increasingly  faster
speeds, and the bike stood up well. We were way over 100+ when we sucked  a panel
out of the ceiling and had to call a halt to the testing.......
 
As they have a full size tunnel, with rolling road, it has been suggested  
that the best way to find the very best shape for an FF would be to make up a  
full size tube ladder chassis complete with front and rear wheels (then you can
 lengthen ot shorten it, as well.) suspend it from the ceiling, and just have
 bolt on front and rear panels, to test the wind flow effects.
 
Sadly they can't replicate the sort of airflow you get on the M3 on a busy  
day, unless we all go and stand in the tunnel and move about..........only  
joking.
 
Off to give a presentation to Transport for London on Wednesday about  
Genesis, and Southampton Uni next week, to talk to their grant finding people  and
chief aero's guy, who knows.
 
Ride safe
 
Ian (P)
 
Remember the First Rule of Acquisition: Find someone else's money, and  spend
it.........
 
 


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[Arthur Middleton home]

>Have just received my wind tunnel results from Southampton University, and
>no big suprises;
>The basic shape is stable at all speeds up to 100+mph and there is a very
>small amount of negative lift at speed.
>
>When we had finished the tests we ran the tunnel at increasingly  faster
>speeds, and the bike stood up well. We were way over 100+ when we sucked  a panel
>out of the ceiling and had to call a halt to the testing.......
>
>As they have a full size tunnel, with rolling road, it has been suggested
>that the best way to find the very best shape for an FF would be to make up a
>full size tube ladder chassis complete with front and rear wheels (then you can
> lengthen ot shorten it, as well.) suspend it from the ceiling, and just have
> bolt on front and rear panels, to test the wind flow effects.
>
>Sadly they can't replicate the sort of airflow you get on the M3 on a busy
>day, unless we all go and stand in the tunnel and move about..........only
>joking.
>
>Off to give a presentation to Transport for London on Wednesday about
>Genesis, and Southampton Uni next week, to talk to their grant finding people  and
>chief aero's guy, who knows.
>
>Ride safe
>
>Ian (P)

Well done. Now that sounds like a worthwhile test.

If one was to get CAD modelled forms CNC machined in something cheap like expanded
polystyrene, and fitted to a dummy chassis (or hollowed out to fit a real chassis), maybe
we could test our fairings before the time consuming bit of making finished fairings.

How much does wind tunnel time cost? I presume this was grant aided?

Arthur.




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[Julian Bond]

ianpegram@... Mon, 15 May 2006 12:37:07
>Sadly they can't replicate the sort of airflow you get on the M3 on a busy
>day, unless we all go and stand in the tunnel and move about..........only
>joking.

Can't you get a truck in there and move it about? ;-)

Doors at an angle on a track that can be rapidly moved from one end to
the other. So you could simulate narrow blasts of air moving down the
body shell?

--
Julian Bond  E&MSN: julian_bond at voidstar.com  M: [phone]
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[Arthur Middleton home]

>>Have just received my wind tunnel results from Southampton University, and
>>no big suprises;
>>The basic shape is stable at all speeds up to 100+mph and there is a very
>>small amount of negative lift at speed.
>>
>>When we had finished the tests we ran the tunnel at increasingly  faster
>>speeds, and the bike stood up well. We were way over 100+ when we sucked  a panel
>>out of the ceiling and had to call a halt to the testing.......
snip
>>Ian (P)

I forgot to ask, what was the drag coefficient? CDa, and cross section area?

Arthur.



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[Royce Creasey]

Julian Bond wrote:

>ianpegram@... Mon, 15 May 2006 12:37:07
>  
>
>>Sadly they can't replicate the sort of airflow you get on the M3 on a busy
>>day, unless we all go and stand in the tunnel and move about..........only
>>joking.
>>    
>>
>
>Can't you get a truck in there and move it about? ;-)
>
>Doors at an angle on a track that can be rapidly moved from one end to
>the other. So you could simulate narrow blasts of air moving down the
>body shell?
>
>  
>

No, it's really difficult to do major turbulence in a real tunnel, you
have to simulate total changes in wind direction - like driving past
trucks in a sidewwind - big energy involved.  Actually cheaper to do
turbulence in sim on  a big computer.  Tunnels are actually obsolecent.

And extremely expensive, you've done well to blag the time.  Did you get
a CD figure?

Royce


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[ianpegram]

Hi
 
Tunnel test time runs out at about £2K per day, which includes the staff  and
sorting out the mounting (if not too complicated). They were suggesting a  
full size frame mock up, with the wheels rolling  in contact with the  rolling
road, to give more accurate results.
 
You could use anything for the experimental bodywork, including  polystyrene.
as long as you can attach it firmly enough. To make best use of the  tunnel,
you would need at least 4 different styles, and possibly a number of  
appendages. If developing a full size 'open' style vehicle you would need a  replica
rider as well, I suppose.
 
This sort of thing could be done with an advanced computer programme, which  
can sit and go through all the variables until it refines the best shape, but  
the best shape in electrons is not always the one that works on the road.
 
To test for side winds you may have to lift the vehicle clear of the  
floor......
 
Cd was  0.35 with the doors on, and 0.45 with the doors off.  Which sounds a
bit high to me, but was saved by a small frontal area. Could do  
better..........
 
Ride safe
 
Ian (P)


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[Arthur Middleton home]

snip
>Cd was  0.35 with the doors on, and 0.45 with the doors off.  Which sounds a
>bit high to me, but was saved by a small frontal area. Could do
>better..........
>
>Ride safe
>
>Ian (P)

What was the Clever prototype drag coefficient? Somewhere around the same, I think, and
you have significantly lower frontal area. To me that sounds OK. I expect Roy's nArrow
Streets to have significantly higher drag than Genesis with 2 front unfaired wheels and a
larger frontal area.

Arthur.




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[Roy Gardiner]

--- In feet_forward@..., "Arthur Middleton" <artmidd@...>
wrote:

> ...I expect Roy's nArrow Streets to have significantly higher drag
> than Genesis with 2 front unfaired wheels

Who said the front wheels are unfaired?

> and a larger frontal area.

No it hasn't Arthur, about the same I would say.

Roy







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[ianpegram]

I think in the real world, it is the ability to close the gap behind the  
rider, that's just as important as the shape of the front of the vehicle, given  
all that we know about streamlining, airflow, boundary layer control,  
turbulence and drag etc
 
Again this could be something to optimise in a wind tunnel, or computer  
programme, and at the level required, I suspect both would be equally  expensive.
 
Ride safe
 
Ian (P)


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[Royce Creasey]

ianpegram@... wrote:

>I think in the real world, it is the ability to close the gap behind the  
>rider, that's just as important as the shape of the front of the vehicle, given  
>all that we know about streamlining, airflow, boundary layer control,  
>turbulence and drag etc
>
>Again this could be something to optimise in a wind tunnel, or computer  
>programme, and at the level required, I suspect both would be equally  expensive.
>
>Ride safe
>
>Ian (P)
>
>  
>

Yup.  It's just big companies like Honad, the ones that can afford to
spend time in a tunnel, that don't understand that the tail is critical
- or maybe their engineers do, but the marketing department hasn't
"evolved" an understanding of that yet.

For normal, innovative type, people the planetary wind tunnel awaits,
it's an innovative idea, you drive the vehicle through some air, rather
than pumping air over the vehicle.  This allows all sorts of other
development to be done too.  We know this works, almost everyone who's
built an FF is ahead of Honad in development terms. And BMW.

Bit surprised you didn't get better than CDa of 3.5, that's prety much
what the computer said 002 made.   Could be the front wheel assembly?
What fuel consumption do you get compared to a standard burger?

Royce




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[Arthur Middleton home]

>--- In feet_forward@..., "Arthur Middleton" <artmidd@...>
>wrote:
>
>> ...I expect Roy's nArrow Streets to have significantly higher drag
>> than Genesis with 2 front unfaired wheels
>
>Who said the front wheels are unfaired?
>
>> and a larger frontal area.
>
>No it hasn't Arthur, about the same I would say.
>
>Roy

Are they fully covered? Is the frontal area of the fairings around the wheels included in
the frontal area calculation? Is the form drag from the outboard faired wheels accounted
for? Is the extra wheel aerodynamic drag accounted for? Is the parallelogram tilt linkage
faired?

One major drag contributor for motorbikes and bicycles is the front wheel. Mileage
marathon vehicles go to great lengths to cover the wheels down to the ground. The tilting
front wheels of STVs, and nArrow Streets, is going to have at least the lower half
uncovered so they can tilt and keep the brake discs cool. Two half covered wheels will
contribute more drag than one half covered wheel.

I ask to get an idea as to what can be expected from different formats of vehicle. If we
are interested in economy, we can just drive a little slower and put up with poorer
aerodynamic efficiency.

Note I didn't say the wheels weren't unfaired, just that "with unfaired wheels, etc."

Arthur.




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[Arthur Middleton home]

>I think in the real world, it is the ability to close the gap behind the
>rider, that's just as important as the shape of the front of the vehicle, given
>all that we know about streamlining, airflow, boundary layer control,
>turbulence and drag etc
>
>Again this could be something to optimise in a wind tunnel, or computer
>programme, and at the level required, I suspect both would be equally  expensive.
>
>Ride safe
>
>Ian (P)

In the real world, motorbikes are really bad for drag, so it is easy to improve on them.
Cars can easily be much better, except for the frontal area. A drag coefficient as Genesis
has recorded I would class as a success. It would be interesting (and maybe very
productive for your project justification) to know what drag coefficient a standard
Burgman with rider has.

Since Royce says the computer predicted something similar for a Voyager, maybe the front
wheel has such a big effect, all we can really if we don't cover it up is fill in the
start of the wake with a tail, and minimise frontal area. I explain the good economy of
the GPZFF by the tail, and the nose fairing helping keep the flow not too wide for the
tail to help. Only helps the top half of the bike, of course.

Arthur.




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[ianpegram]

 


>For  normal, innovative type, people the planetary wind tunnel awaits,
it's an  innovative idea, you drive the vehicle through some air, rather
than  pumping air over the vehicle


I like the idea of the planetary wind tunnel...and to give them their due  
Southampton Uni felt it was the best way to have tested the project so  
far...They seem very down to earth about the whole thing, and not terribly  precious
about their tunnels abilities, very refreshing.
 
Genesis is still not as clean a shape as I would like, partly due to the  
design and vehicle profile, and partly due to having to rush to get the bike  
finished by the end of the funding deadline. At least we are getting something  
else useful out of that big flat radiator stuck at the front.......(very hot  
feet)
 
As for fuel consumption; I believe Paul has said thet he gets about 38mpg,  I
have been getting about 80mpg in pottle mode, and have pulled out one run of  
105mpg. I am now keen to get out and give it a run with the new bodywork, but
 still have lots of interior parts to make, as well as the air deflection
ramps  around the door apertures. (and another busted screen)
 
As for big companies, they will eventually morph their bikes into something  
more like ours, its just very frustrating that we are so far in front, and  
losing the lead all the time. Then they will claim it as some great innovation  
they have made.......
 
Ride safe
 
Ian (P)


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[Ian Kew]

At 10:40 16/05/2006, ianpegram@... said:
>As for fuel consumption; I believe Paul has said thet he gets about 38mpg,  I
>have been getting about 80mpg in pottle mode, and have pulled out one run of  
>105mpg.

38mpg from a Burgman? That sounds very low.  I'd expect most owners to average around 50mpg.

I'd have thought you need to both fill up and go for a reasonably long ride together to compare, perhaps swapping bikes several times en route.  Paul never seems to get very good consumption and that should average out the figures.

80mpg is damn good though.  Shows that just cleaning up the closing air can really make a difference to motorcycle fuel consumption - your frontal area has to be around the same as Burgman and a rider, if not slightly larger.


Ian

www.voyager03.co.uk

Look out, there's a monster coming.



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[Arthur Middleton home]

snip
>As for fuel consumption; I believe Paul has said thet he gets about 38mpg,  I
>have been getting about 80mpg in pottle mode, and have pulled out one run of
>105mpg.
snip
>Ian (P)

Comparing Blez riding with someone else, like me, for example, is pretty meaningless
unless he is riding both bikes. Also I would be very suspicious of a big change in fuel
economy like the jump to 105mpg on the one run unless driving style is very different
(i.e., much smaller throttle opening). It is easy to get these things wrong, especially
when your speedo suddenly changes to km from miles. 80mpg sounds plausible if driven
within legal speed limits.

Arthur.




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[bobwreford]

--- In feet_forward@..., ianpegram@... wrote:
>
>
> I think in the real world, it is the ability to close the gap
behind the  
> rider, that's just as important as the shape of the front of the
vehicle, given  
> all that we know about streamlining, airflow, boundary layer
control,  
> turbulence and drag etc
>  
> Again this could be something to optimise in a wind tunnel, or
computer  
> programme, and at the level required, I suspect both would be
equally  expensive.
>  

Well done Ian for doing it measurably!

Am I right in thinking that alterations to drag can be measured by a
sort of free wheeling rolling test in neutral (Ho! Ho!)

I had in mind putting my bike in neutral at say 60 mph and seeing
how much slower it was after 200 yards?

Then repeat the test immediately with different body panels.

I realise that to come to a standstill would give the rolling
resistance too great an impact on the test.





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[Arthur Middleton home]

snip
Bob wrote:

>Well done Ian for doing it measurably!
>
>Am I right in thinking that alterations to drag can be measured by a
>sort of free wheeling rolling test in neutral (Ho! Ho!)
>
>I had in mind putting my bike in neutral at say 60 mph and seeing
>how much slower it was after 200 yards?
>
>Then repeat the test immediately with different body panels.
>
>I realise that to come to a standstill would give the rolling
>resistance too great an impact on the test.

Correct. You can correct for rolling resistance, but as it is quite high this is a
potential for significant errors. I think it would be a useful test if the same bike is
used each time. The rolling resistance of different bikes can be very different so it is
not as useful comparing between them. The HPV people use this technique.

Arthur.




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[Atholl Reid]

Hello all

Arthur wrote:
>>>
<snip>
The rolling resistance of different bikes can be very different so it is not
as useful comparing between them. The HPV people use this technique.
<<<
The bunch of HPV people that I ride with do "roll-down" tests on a fairly
regular basis on the same roads.

Many of the bikes and trikes are gradually modified - new tyres, wheels,
hubs, tailbox fairings ... those sorts of things - and the biggest
difference that I have seen is from no tailbox fitted to having a tailbox
fitted without any other changes to the bike.

One week - no tailbox.

A couple of weeks later - tailbox fitted.

While being quite non-scientific (no measurement of temperature, wind
direction/speed, tyre pressures - things like that), with the tailbox
fitted, the top speed reported was higher and the distance travelled
further.  I'm not claiming that the rolldowns are conducted in a scientific
manner.


There was a bit of a rush after the recent Commonwealth Games in Melbourne
to find out what was going to happen to all of the signs that had been made
- I'm sure that there will be lots of new tailboxes around soon.

Squidely pop

Atholl (Canberra Australia)


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[Royce Creasey]

'Roll down' testing was a respectable method of establishing all sorts
of stuff back in the Voyager development time (1988-90), we used to run
down from 70 to 60, in top gear, against a stopwatch.  This is where the
projected 002 Cda of 3.5 and a bunch of fuel consumption figures that
proved to be quite acurate came from. I was just the driver, someone
else operated the computer and understood the fuel map we got from
Reliant which was an important component.

We found that fitting a tail section provides the benifits you mention
as well, plus reduction in noise.  The current banana tail section was
particularly impressive in this respect.  FJ is not a styling
excercise!  Of course fitting a tail to a two-wheeler means it looks
completely different to a motorcycle
and means that Honad, BMW, Triumph, Yamaha and any other manu you care
to mention don't have the balls to try it - hence the dogs dinners like
the G-stryder and the DN01 and so on.

Actually it's not just Motorcycle manu's who are afraid of what people
will say (poor dears) In me F.1 days we developed an airbox, with Rolls
Royce, which was shaped to maximise flow but looked unlike the airboxes
that everyone else was runnings.  Gave another 400 rpm at the end of the
Goodwood straight in testing.  We took it to South America and South
Africa but never fitted it to the car 'cos Frank was afraid people would
laugh.  He's probably got over laughing by now I guess.  We never
worried about people laughing at us, we were too busy laughing at the
motorcycles we'd just stuffed.  I still am.

Royce
 
Atholl Reid wrote:

>Hello all
>
>Arthur wrote:
>  
>
><snip>
>The rolling resistance of different bikes can be very different so it is not
>as useful comparing between them. The HPV people use this technique.
><<<
>The bunch of HPV people that I ride with do "roll-down" tests on a fairly
>regular basis on the same roads.
>
>Many of the bikes and trikes are gradually modified - new tyres, wheels,
>hubs, tailbox fairings ... those sorts of things - and the biggest
>difference that I have seen is from no tailbox fitted to having a tailbox
>fitted without any other changes to the bike.
>
>One week - no tailbox.
>
>A couple of weeks later - tailbox fitted.
>
>While being quite non-scientific (no measurement of temperature, wind
>direction/speed, tyre pressures - things like that), with the tailbox
>fitted, the top speed reported was higher and the distance travelled
>further.  I'm not claiming that the rolldowns are conducted in a scientific
>manner.
>
>
>There was a bit of a rush after the recent Commonwealth Games in Melbourne
>to find out what was going to happen to all of the signs that had been made
>- I'm sure that there will be lots of new tailboxes around soon.
>
>Squidely pop
>
>Atholl (Canberra Australia)
>
>
>[Non-text portions of this message have been removed]
>
>
>
>
>
>Yahoo! Groups Links
>
>
>
>
>
>
>
>
>
>
>  
>

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[Arthur Middleton home]

snip
>There was a bit of a rush after the recent Commonwealth Games in Melbourne
>to find out what was going to happen to all of the signs that had been made
>- I'm sure that there will be lots of new tailboxes around soon.
>
>Squidely pop
>
>Atholl (Canberra Australia)

Corriboard is cheap anyway (as used in Genesis proto bodywork). I bought a few sheets to
make a skeleton for a model of a fairing recently. About 8 euro for 1220mm x 2440mm x 4mm
thick sheet. I think 3mm may be better for HPV tail box building, as 4mm is too rigid to
shape easily. I made the mould for the GPZFF tail head fairing from 3mm and 4mm
Corriboard. OK for prototyping; not great for finish quality.

Arthur.




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