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On 07/10/2019 at 2:00 PM, forteh said:

edit: on the winning team, one of the drivers commutes 400 miles a week on his recumbent bike, he was pushing 30-40 minutes sessions at a constant 90rpm cadence.  Once he was done bombing round the track all day long he then went and cycled 35km home in the dark :o:o:o

I've just spent ages planning the build then read this. Probably need to spend more time riding as that is likely where all the lap time is from :lol:

Do you have any pics of the finished thing? What did you do for a fairing in the end?

Got a load of parts on the way to start the build, MIGHT be ready for the first round but probably going to chill out and be ready for Round 2.

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Screen_Shot_2016-04-20_at_4.22.55_PM.0.0

Screenshot_20200109-163221_1.thumb.jpg.1236363efff1ac0bfef8b46851ca4c57.jpg

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That face :wub:

 

:lol:

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It's my best 'will some bits fall off or not when I get to ride the thing' face :lol:

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@monkeyseemonkeydo I can see you looking...... Do you know of any basic CFD software (preferably with inbuilt CAD) that's free and easy to use? Long shot I know, but I'm wondering if a different body shape to 'the norm' (most of the teams seem to share the same mould so all the cars look the same) might be beneficial...

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18 minutes ago, Adam@TartyBikes said:

@monkeyseemonkeydo I can see you looking...... Do you know of any basic CFD software (preferably with inbuilt CAD) that's free and easy to use? Long shot I know, but I'm wondering if a different body shape to 'the norm' (most of the teams seem to share the same mould so all the cars look the same) might be beneficial...

There is free 2D CFD software out there but I can't think of anything that would do 3D which is probably more what you're after. I'm sure you know what you're aiming for though- general 'slipperiness' is always good; if it looks right it's probably 80% there; minimising frontal area is important; enclose wheels as much as possible (interestingly the top solar challengers are now 4-wheel steer so that they can both minimise steer angles all round to reduce how much space there needs to be around each wheel (effectively halfing the required opening and wheel shroud width at the front while slightly increasing the rear end) and also deliberately crab the cars to minimise any drag induced by oncoming wind direction). You should also look into creating a simple disc shroud for each wheel as although they'll be in relatively still air the system will be more efficient if you reduce the rotational drag of the wheel by  hiding the spokes. Obviously for that one minimum weight is also important...

Edit: Actually, I've just checked and although I thought OpenFOAM was just a meshing program it looks like it offers a complete package which is worth checking out. You'd probably need to do the CAD elsewhere but once you have a model OpenFOAM might be worth looking at.

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Posted (edited)

On 02/01/2020 at 0:38 PM, Adam@TartyBikes said:

I've just spent ages planning the build then read this. Probably need to spend more time riding as that is likely where all the lap time is from :lol:

Do you have any pics of the finished thing? What did you do for a fairing in the end?

Got a load of parts on the way to start the build, MIGHT be ready for the first round but probably going to chill out and be ready for Round 2.

Fairing wise it was just a bit of plywood to make a boxy bikini fairing, zero aerodynamics :D
I don't think wheel shrouds are allowed although there was one guy doing the curby race solo in a fully enclosed car, he was essentially lying down in a kevlar slug.  Had to stop part way through to cut extra sight holes in it though because he couldn't see; trying to draught off him was virtually impossible with our breezeblock though!
 

edit: haven't actually got many photos of it finished, too busy trying to patch the bodywork together at 10pm the night before the race!  I'll see if I can find some more that others took.

 

IMG_20190916_094705.jpg

IMG_20190916_095929.jpg

 

edit2: some stolen from facebook!
71472787_10156694818711304_2412432690067275776_n.jpg.139e606f76acb27c906f164584e8dc5b.jpg

71566877_10156694813716304_5356237883592146944_o.thumb.jpg.9d2e77796a39d188df3e46e727739ece.jpg

it looks like hard work, mainly because it was, I'm really unfit these days and the beard was adding to the aerodynamics in it's own special way :D

72653538_10156694818886304_6932712252428517376_n.jpg

72561285_10156694814211304_3845386637898940416_o.jpg

I did do some draughting though!

Edited by forteh

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16 hours ago, monkeyseemonkeydo said:

Snip

That's ace, thanks Dave. I downloaded OpenFOAM last night but having no CAD model to put in there was a bit limiting :lol: I've decided I'm over-thinking it and going the 80% route of 'if it looks right' will do the job... great to know there is an option though, thanks again for the info!

 

Cheers for the pics Ed - that is definitely not an aero beard is it B) Are you going to have a crack at any other rounds this year?

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7 minutes ago, Adam@TartyBikes said:

That's ace, thanks Dave. I downloaded OpenFOAM last night but having no CAD model to put in there was a bit limiting :lol: I've decided I'm over-thinking it and going the 80% route of 'if it looks right' will do the job... great to know there is an option though, thanks again for the info!

 

Cheers for the pics Ed - that is definitely not an aero beard is it B) Are you going to have a crack at any other rounds this year?

I don't know if I'm getting the wrong end of the stick here but Fusion 360 is a free design software program. It's pretty easy to use and there's tons of guides online how to use it. I'm sure you won't struggle to use it anyway.

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Cheers Anal, I'll have a look at that...

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I wouldn't bother with trying to model the aero, just make something that looks right, think torpedo and aerofoils and you won't go much wrong.  The winning car was a plain cigar shape made from a carbon front half and the back end was made from correx sheet and lycra to fill in the gaps.

The plan is theoretically to do some more rounds this year, not sure if timing will allow though, also need to make a number of mods to the car and time is rapidly running out to try to meet the first meet date.  Might get it ready for curby in september again :D

Edited by forteh
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2 hours ago, Adam@TartyBikes said:

'if it looks right'

That idea as far as aero was concerned was blown out of the water by that air dam vs. splitter vs. conventional bumper aero comparison you showed me for MX5s a while back :P  

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10 hours ago, Adam@TartyBikes said:

having no CAD model to put in there was a bit limiting :lol:

FreeCAD is another option for CAD software. I haven't tried it myself as we get Solidworks at work but I've read pretty good things about it :)

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Or just acquire a copy of solidworks and teach yourself, I can offer training at a reduced consultancy fee!

Hey, I helped Dann2947736393-040828 over the phone with his 3D modelling in solidworks so technically his first degree is all my fault :D

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I've been working in my room doing a paint job and installing parquet(to all the flat), quite happy with the result :)

 

Before:

IMG-20190702-210154-274.jpg

 

Now:

IMG-20200111-204853.jpg

IMG-20200111-193718.jpg

And got this today :w00t:

IMG-20200111-151339-543.jpg

Edited by Guillermo M.
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Dave, Ed, thanks! I have a copy of Unigraphics somewhere (think it uses the same engine as Solidworks?), however someone has beater me to it anyway, and saved me a load of work...

My theory was that a lot of the current cars in BPCC use the same rear design because they share the mould around the drivers / teams, and said mould had been made based around the convention for trikes, because obviously the rear is a lot narrower:

p1020110.jpg

Guy_martin_at_Shenington.jpg

(Yes that is Guy Martin having a crack at their 24hr race!)

However, with a 4 wheeler being much wider at the back, I wondered if rotating that tail design through 90 degrees would be better - and also a shitload easier to manufacture using the rudimenary techniques I have in mind :lol:

m%20new%20shape.jpg

m%20f%201.png

m%20w%201.png

m%20w%202.png

m%20f%203.png

This guy's simulation puts drag at an astonishing 6N at 15m/s! Obviously we're never going to get anywhere near that but at least it proves that changing the tail shape isn't a complete dud.

He also made a good point about having the height of the tail matching the line where air will split (under and over) at the nose, which made a lot of sense.

 

Edit: Bonus image of the kevlar slug Ed mentioned above :D

48712816222_dbbebb20de_b.jpg

I think he's onto something to be honest...

aero_1.jpg

solar-car-evolution.jpg

Cambridge Uni solar power car above, I doubt they will have waved a finger in the air when it came to designing the body shape :lol:

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Commuted home yesterday... needs a few small tweaks but no bits fell off! A bit more testing to do then ready for bodywork.

Much tougher to pedal than I expected - it's allll about the quads, I didn't realise how much MTB uses core, arms, and other leg muscles too!

IMAG1736.jpg

Ed, don't suppose you know what yours weighed?

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The fat end of 40kg I reckon :D
It was really energy sapping on the hill at curby!

The wingracers car (no. 1 plate and winners last season) was about 26kg :o

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There's a hill at Curby? :lol: Guess you don't feel it in a car!

Thanks for that, need to check weight but hoping to be near that 26kg...

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After the end of the straight about halfway round the bend it starts to climb, it's only a slight incline but after the first few laps you soon realised it was there when the speed dropped off :D

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Makes sense now you think about it! I can certainly see how hills are an issue with additional weight...

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Latest cabinet build from me, doesn't look like much but a fair bit of machine work went into it!

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Nice, love that joint!

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Rebated joints are just dead simple but when done in ply look so cool!

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Well, it works, and it drifts like every RWD car should :D

Weighs almost bang on 30kg like this.

Engine needs a lot of work if we're going to trouble the top boys!

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