Soapbox tech

Forum for discussing motorsport events & participation
Post Reply
User avatar
campbell
Posts: 17191
Joined: Sat Mar 25, 2006 12:42 pm
Location: West Lothian
Contact:

Soapbox tech

Post by campbell » Mon May 23, 2016 5:20 pm

Inspired by our own istoo, as he and I (and others?!) prepare for the inaugural Royal Deeside Speed Festival (RDSF).

No competitive secrecy here ... I think ;-)
http://www.rathmhor.com | Coaching, training, consultancy

User avatar
Dominic
Posts: 14411
Joined: Sat Mar 19, 2005 10:14 am
Location: Milton Of Campsie
Contact:

Re: Soapbox tech

Post by Dominic » Mon May 23, 2016 7:55 pm

What's the technical regulations?

I would think something aerodynamic would be advantageous. Low centre of gravity. Low rolling resistance, road bike wheels, pumped hard. I suspect that lightweight is not so essential, I am sure Robin will advise on that one.
http://www.dsaccountancy.com

1999 Lotus Elise Sport 135'99

User avatar
Stevoraith
Posts: 1068
Joined: Sat Oct 07, 2006 5:31 pm
Location: Kirkcaldy, Fife

Re: Soapbox tech

Post by Stevoraith » Mon May 23, 2016 8:31 pm

Yeah, I'd have thought if it's too lightweight it won't pick up speed. But if it's too heavy it won't change direction.

Best to make it as light as possible (without going overboard) with the ability to add ballast as required.
VX220 2.2 - Gone
BMW 335d Touring F31- Fastest car on the road
MINI Cooper 1.5- More fun than the BMW

User avatar
rawsco
Posts: 938
Joined: Wed Feb 11, 2015 2:23 pm
Location: Falkirk

Re: Soapbox tech

Post by rawsco » Mon May 23, 2016 9:36 pm

Copy Guy Martin, he went for the world record soap box hingy. Nudged 100 I think.. The more weight to frontal area the higher your terminal velocity so heavy and slippery. Guy filled his with full water bottles. however hussling the weight round the corners will be a problem. From memory this was guys undoing resulting in a substantial crash. bike wheels aren't really built for lateral loads (loads of -ve camber.) and stub axles (apart from Cannondale hubs for the lefty fork.)

Skinny tyres and high pressure worked better for speed for Guy but again buggered up corners. It's gonna be a trade off between top speed and cornering ability. Know your course I'd say and your physics!
Rawsco
2021 - Tesla M3LR
2019 - Exige 410

User avatar
Dominic
Posts: 14411
Joined: Sat Mar 19, 2005 10:14 am
Location: Milton Of Campsie
Contact:

Re: Soapbox tech

Post by Dominic » Mon May 23, 2016 10:01 pm

Don't forget, good aero is as much about how you depart the air as much as it is about how you enter it. Tear drop FTW
http://www.dsaccountancy.com

1999 Lotus Elise Sport 135'99

woody
Posts: 5624
Joined: Mon Dec 26, 2005 4:03 pm
Location: Southside Triangle

Re: Soapbox tech

Post by woody » Mon May 23, 2016 10:06 pm

Wheel chair wheels and ply... however read the regs ages ago and seem to remember wheels are restricted to 14".

User avatar
campbell
Posts: 17191
Joined: Sat Mar 25, 2006 12:42 pm
Location: West Lothian
Contact:

Re: Soapbox tech

Post by campbell » Tue May 24, 2016 7:56 am

Regs are pretty open.

Quite frankly if Team FMC make it to the start line with something that stops and turns, I'll be delighted :-)

Currently in pursuit of key parts. Blueprint drawn. Engineering help will soon be sought re bearings and axles so be ready guys.
http://www.rathmhor.com | Coaching, training, consultancy

User avatar
robin
Jedi Master
Posts: 10525
Joined: Mon Mar 27, 2006 1:39 pm

Re: Soapbox tech

Post by robin » Tue May 24, 2016 8:11 am

Image
I is in your loomz nibblin ur wirez
#bemoretut

User avatar
Fluoxetine
Posts: 1423
Joined: Thu Aug 17, 2006 5:57 pm
Location: Baile Átha Cliath / Abergloom

Re: Soapbox tech

Post by Fluoxetine » Tue May 24, 2016 8:39 am

Nah - More like this, shirley?! :P

Image

User avatar
alicrozier
Posts: 4368
Joined: Thu Sep 01, 2005 12:58 pm
Location: Aberdeen

Re: Soapbox tech

Post by alicrozier » Tue May 24, 2016 8:43 am

:withstupid
Is that tut and Scotty?
All characters appearing in this post are fictitious. Any resemblance to real persons, living or dead, is purely coincidental.
Any references to laptimes, speed or driving on the public highway are purely for dramatic effect.

User avatar
Ferg
Posts: 3936
Joined: Fri Sep 04, 2009 11:56 pm
Location: Auld Reekie

Re: Soapbox tech

Post by Ferg » Tue May 24, 2016 10:24 am

I'd been hoping to do this, but keep looking at whats required and not sure I can commit with work and space and other stuff going on..

I had all sorts of beautiful fag packet type designs but had an attack of realism and went looking for the quickest route to a working kart. The rack and pinion steering is the main issue for me. For the rear though have a look at this kart for simplicity.

Image

I was thinking similar to the above using two bmx forks facing rearwards with BMX wheels. Means the wheels are strong and the brakes are built in already. Didn't end up with a steering solution as I havn't found a suitable stub axle assembly yet.

:thumbsup

User avatar
Ferg
Posts: 3936
Joined: Fri Sep 04, 2009 11:56 pm
Location: Auld Reekie

Re: Soapbox tech

Post by Ferg » Tue May 24, 2016 10:31 am

Simple steering.

Image

istoo
Posts: 725
Joined: Sat Mar 29, 2014 8:52 pm

Re: Soapbox tech

Post by istoo » Tue May 24, 2016 10:51 am

There are relatively strict rules to stick to for size and footprint.
I will double check but fairly suire the regs stated no string or foot actuated steering.

but advantages are;
Low CoG
long, width is determined by the track we are racing down, so a longer narrow car will be faster (less drag) than a wide car if its just straight lines (think dragster) if its twisty will need some width.
Weight is your friend, heavier cart will accelerate quicker and have a greater terminal velocity than a lighter one in the same conditions. but see above comment on the track.
I have opted for BMW wheels on stub axle with semi slicks, agian dont know what cornering we are expected to do.
front wheel steering
rear wheel braking
Steering - sussed as per previous thread. I also found an old tractor mower which had some really simple pitman type setup, worth a scour of the local garden cente / tip / scrappy. The kids loved that by the way...


That all said and done. I am with Campbell, just making it would be an achievement!

Team 'Duct tape and hope'
S2 111s

User avatar
Sanjøy
Posts: 8808
Joined: Sun Oct 02, 2005 8:23 pm
Location: Edinburgh Hamptons

Re: Soapbox tech

Post by Sanjøy » Tue May 24, 2016 12:16 pm

Seriously nearly 24 hours and nobody has posted these?

Image

Image

Image
W213 All Terrain

istoo
Posts: 725
Joined: Sat Mar 29, 2014 8:52 pm

Re: Soapbox tech

Post by istoo » Tue May 24, 2016 12:50 pm

Sanjoy wrote:Seriously nearly 24 hours and nobody has posted these?

Image
cartie can go on a diet no fecking chance i am!
S2 111s

Post Reply