New car (dougal/dylan) build
Posted by bobc on Feb 2, 2012 in Uncategorized |
up to 2/2/12
design mostly complete
front steering/braking system made & assembled
monocoque 1/2 mould made & prepped
wheel mould made & prepped
trial vacuum bagging process successful
trial 3d printed fairing (courtesy of Siemens MC IC) in process
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GreenPower- The Comment TreeAnother new addition, this fine ‘Lilly Pilly’ or Comment Tree when in The Greenpower Centre, was kindly grown and donated to Greenpower by Architectural Plants, www.architecturalplants.com. The ingenious pot it is in has removable sides to allow the roots to be pruned – essential for long term survival of plants in pots, and therefore highly […]
- The Comment Tree
16 feb 2012
Had a full day on the car today, being 1/2 term, Emily, Siobhan, Beth and Lucy all weilding paintbrushes as we went for the biggy – vacuum bagging the bottom 1/2 of the monocoque. It took us about 5hrs altogether but we left it sucked down to 0.1bar with a big cutout for the speed controller and the crotch strap harness location all bonded in. That is a big piece of composite – over 2metres long – to make in one hit, and it will be hard to do the top half in a normal car club evening, even if we get everything (and I mean EVERYTHING) ready the week before. It takes 10 square metres of carbon weave to do each half of the monocoque – there’s a lot of money going into this build.!
The first wheel came off the mould last week and looks awesome; all the hubs will be glued in together when we’ve made all 5. The last 3 hubs are still at the water jet cutters; I’ll check on progress tomorrow. Rich now has the ally tube to make the rear hubs; I will pick up a length of ~22mm CDS round tube for the roll bar and back axle at the weekend.
Motor mount with chain adjustment and heatsink are all in one assembly – I just remembered it has to cope with sprocket changes (f24/f24+) as well as tensioning so I might have to extend the adjustment slot… Rich has given me a design which I’ve modified a little & will probably have to modify a little more before I get it lasered ;^)
21 feb 2012
Normal car club tuesday evening. Work on new car continues, plus more work to bring brian up to date…
Vacuum bagging: we made another wheel. The first wheel was built up with hole for valve access & kojak tyre. Looks sweet.
The bottom monocoque half was cleaned up. It is SO light, stiff and strong, just as we hoped. Beautiful job, absolutely mint.
Transmission sprockets had tooth counts checked; for 1/4″ chain motor sprockets are 15 and 18 teeth (f24 and f24+) and the wheel sprocket is 75 teeth. Going to 8mm chain, that means 80 tooth on the wheel and 16 or 19 on the motor. So we need 2 off each 16 and 19 tooth 8mm sprockets and a load of 8mm chain.
Water jet parts have a bit of delay, they are upgrading their machinery – probably early March. Good night’s work.
28 feb car club night
3 jobs tonight
1)make a wheel: The mould had been waxed so it was warmed and sprayed with PVA mould release. The rim had carbon fibre tape wrapped round it and the mould was painted with epoxy. 2 layers of carbon fibre weave were put down then the rim on top. epoxy/glass bubbles mix was used to fill the gaps then the structural foam core put in. 2 more layers of weave were placed over the top and then a layer of microperforated peel ply. Finally the “nappy” layer to soak up excess resin and the whole put in a bag ready for evacuation. Left with the vacuum pump running overnight. That’s the third wheel done now – 2 more for the full set + spare ;^)
2) Sort out Brian. The old gearbox bracket was removed and the motor moved to its new location. The drive wheel was taken off to be threaded for the freewheel with the 80 tooth 8mm chain sprocket on.
3) design the “paint job” for the new car. A set of views of the car in line drawing format were given to all the car club members to put down their interpretation of the martini racing colours. Lets hope we get some good ones back – I kicked off with an example that looks OKish & adds a bit of shape to the car but even I could do better & I’m sure some of the girls will.
Motor mounting clamps and fins are at the laser cutters. So are some steering yoke bearing holders: it will be running on deep groove ball bearings. The fins incorporate CAUC lettering… and why not!
6 march 2012 – car club night.
Busy night at the club tonight; we made another wheel for Dylan, Brian’s motor was bolted in its new position – the hub has been threaded 1.37x24tpi for the freewheel and an 80 tooth 8mm chain sprocket laser cut for it. The freewheel fouls the axle bearing grubscrews so they’ll have to be replaced with shorter ones. Various girls started actually designing the martini stripes for Dylan. The fancy fins and motor brackets are here and there was general approval of the CAUC lettering on the heatsink fins! Rich took the mould home to tart it up & move stuff about to make the monocoque top. Time to ring the water jet cutting place to see if they’ve been able to do the remaining 3 hubs.
March 13 – car club night
Final wheel done tonight. Considering that Brian will also need a sprocket change (f24/f24+) we realised the motor should be positioned so the sprocket could come off, and preferably with easy chain tension adjustment. So finally we thought we’d try the motor mount we made for Dylan on it. I need to get some socket cap M5s for the clamps. I had welded up the rollover bar assembly using scrap 20mm box from my brother’s shop (the main roll bar is 25.4mm thick wall CDS tubing – we’ll also use this for the back axle). 8mm chain and half the required sprockets are here.
March 27 car club night,
Spent most of the time getting Brian and Zebedee mobile again (after being laid up for the winter) and finally fixing the new motor clamp/ chain adjuster on to Brian – along with 8mm chain drive and freewheel.
On the new car, all the wheels are now made ready to have the hub parts glued in. The foam was bent for the monocoque top & various small foam pieces cut out in preparation for making the top half.
Two grand old ladies (now at college) Hannah Harding and Hannah Mullins called in & helped: lets hope we can find some new driving talent to compare with these two! Easter holidays now so we plan to have a couple of driver training days and hopefully we can spend a day making the monocoque top half.
April 17 car club night
The laser cutter have been busy over easter and we have most of the metal bits to go into the car. Everyone was most taken with the angle reinforcement which will support the rollbar/ harness shoulder straps/axle bearings. The rear hubs have been tig welded and the wheelhub parts machined.
All the foam core parts were finished on the monocoque top half, and necessary composite supplies ordered.
The roll bar bolt holes were fettled to bolt nicely to the reinforcement.
Zebedee had its dash reprogrammed to go back to proportional control (just leaving pulse/glide for very low power levels). This was tried in the playground and appeared to work like the design intention!
Brian was run with the new 8mm chain singlespeed transmission and seemed to work well.
The corporate challenge will be run in a couple of weeks so it’s likely that next week will be spent getting everything ready for that.
may 8th: car club night -
OK I missed a week – last week we got ready for the top half monocoque buildup and glued the hubs into a couple of wheels. This week we had a longer session (started early) and laid up the top half of the car. It took exactly as long as doing the bottom half (i.e. we’ve not gotten any better at the job). Longer in fact because we tried to reuse the old bag & it turned out to be full of holes and wouldn’t vac down below 0.6 bar. Now both halves are done we have to come up with a plan to glue them together!
Oh yeah – we had the season opener/corporate challenge since the last blog post. Silverstone had awful weather so all the electronics packed up & brian stopped altogether. So we didn’t do the 2nd race with zebedee because we were worried about the drivers freezing. Batteries looked OK though as far as I could tell. I tried to get somebody doing a discharge test at the school but the timer is not reliable – I’ll swap it for the other one & try again….
15th May – car club
I turned up late as I’d been away on business. The top half of the car was out of the mould and having a rebate routed to where it would join to the bottom half. Looking good for an epoxy glueing session in the near future! The remaining 3 ally hub mounts were sanded to provide a key for the epoxy to glue them to the wheels. We have some internal bulkheads and more seatbelt mounts to fit in the car monocoque halves before we can glue them together – Rich is the man, I’m sure he’ll have a plan by next week….