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Anatomy of Slippery Anne - Mark Atkinson - 26-05-2018
Posting questions about my recalcitrant BLIC Magneto has reminded me that I should be posting some updates on the cars progress.
As she stands, which is now on her correct 6" brake wheels, Slippery has functioning brakes and steering, her seats are in place and the floor is complete. The rear dampers still need to be contrived and the engine needs to go in mated to the nice close ratio box that Andy Bird built for her.
I have not yet covered the wood frame with Irish Linen, as I will have some work to do once all the chassis work is done.
I also need the radiator core, which is work in progress at a specialist who has the skills to make one angled at 45 degrees, but still has the tubes parallel to the chassis.
Taken when I had the whole car apart to paint her components and fit the floor and seats. have attempted to attach a few pictures, hopefully visible below. The Gremlins have gotten at my efforts, as the post draft which will not let me see what images I am posting, so if the pictures do show up I am sorry for no an annotations.
The seats and chassis pictures are self evident, I have also inserted a shot of the front brake lever I fitted along with the bushed central pivot intended to stop the cross shaft flexing forward under load.
You will also be able to see the front chassis swan neck and parallel rear springs.
I have included a picture which shows how the drivers right hip has to slot under the bodyworks frame.
Regards, Mark.
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A few more pictures, I will post some of the engine in a few days time.
Regards,
Mark.
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RE: Anatomy of Slippery Anne - steve davidson - 26-05-2018
That's some beautiful workmanship, can’t wait to see the final product
RE: Anatomy of Slippery Anne - Ian Williams - 26-05-2018
Superb Mark a credit to you!
RE: Anatomy of Slippery Anne - Ruairidh Dunford - 26-05-2018
I really like your car, very nice!
RE: Anatomy of Slippery Anne - Erich - 27-05-2018
Beautiful, Mark! Your workmanship is outstanding. What sort of specs will the engine have?
Erich in Seattle.
RE: Anatomy of Slippery Anne - Mark Atkinson - 28-05-2018
Thank you for your kind comments about the car, reading Dave's remarks about building his 'Cheapskate Special' have struck a cord with me. Similarly to Dave I have used materials collected over the decades. The boat tail is built from 40 year old Silver Spruce which was left over from building a aeroplane and some of the aluminium is also from that project.
These type of projects really do eat up that most precious thing, time, I started building Slippery Anne several years ago, as and when time allowed. I now wonder what I have built, despite having two seats and all the added weight of the extended chassis, the car is actually very light, Erick asked me what spec the engine is, well it has a 1924 crank case containing a 1 1/2" Phoenix crank, it has a compression ratio of 7.5 to 1. The Roots Supercharger has a swept volume of 33.46 cu.in and is driven directly from the engines timing gear, it breaths through a bronze 1 1/2" SU jetted to run on petrol. At present the Supercharger is driven by a 14 tooth gear giving a low level of boost, ultimately this could be dropped to 11 teeth effectively doubling the boost pressure. On the Dyno last week, with a faulty Magneto already causing ragged running, it produced 40 BHP at 4000 rpm, but due to the Mags issues it struggled to rev much beyond 5000 rpm by which point it was backfiring and missing terribly, sounding like a firecracker, but still managing to give over 50 bhp, but with no more revs to give. Once the Magneto is fixed I expect a good 7000+ rpm and between 60 - 70 bhp with a 13 tooth drive gear fitted.
Given the cars 19" wheels and 6" brakes, allied to its slender weight Slippery is starting to look a little intimidating, especially as my 16 year son old is eying it covetously. No brakes, no roll protection, no harness and the MSA requirement that Nomex suits be worn make for a slightly worried Dad.
From a positive perspective, the car has a very low centre of gravity, with the exception of her 2 gallon fuel tank, all the main mass is contained within the wheel base and even a tall drivers shoulder height is only a little above the top of the 19" wheels, so the dynamic qualities of the car should be excellent. I think we will limit her use to hill climbs and sprints.
Magneto issues permitting, I hope to take it off the Dyno and drop the engine into her in the next few days, I will post some pictures then.
Regards, Mark.
RE: Anatomy of Slippery Anne - Bob Culver - 28-05-2018
The splayed springs of a Seven are curious. On the stock cars between full bump and rebound must be a marked change in spacing. But it is curious that all the extra weight was incurred to obtain parallel on a racer.
Are the chassis channels derived from Sevens or folded up especially? Recent questions about welding etc suggested the question of how made originally. Hot rolled or cold folded? Mass heating was suggested for straightening but I dunno which would be most tolerant of.
With all that work, the prospect of spinnig the car out backwards would keep me awake at night!
RE: Anatomy of Slippery Anne - Tony Betts - 28-05-2018
Looking really nice mark,
How did the big bulg on the drivers side come out?
A bit worried you might be building it up in the kitchen though.
Tony.
RE: Anatomy of Slippery Anne - Mark Atkinson - 28-05-2018
(28-05-2018, 10:15 AM)Bob Culver Wrote: The splayed springs of a Seven are curious. On the stock cars between full bump and rebound must be a marked change in spacing. But it is curious that all the extra weight was incurred to obtain parallel on a racer.
Are the chassis channels derived from Sevens or folded up especially? Recent questions about welding etc suggested the question of how made originally. Hot rolled or cold folded? Mass heating was suggested for straightening but I dunno which would be most tolerant of.
With all that work, the prospect of spinnig the car out backwards would keep me awake at night!
Hello Bob,
I think the parallel springs came about for several reasons, both Gordon England and Austin using them at more or less the same time, Mrs JoJo having a very similar configuration to Slippery Anne.
I recently chatted with the driver of a Boulogne car, who conveyed to me a vivid impression of the towering and teetering high C of G.
I mentioned in my previous post that in Slippery the drivers shoulder is not much above the wheels, on a Boulogne car the divers elbow is higher, that back in the day they also employed a riding mechanic must only of exacerbated the phenomena.
On Slippery Anne, the masses are well managed, the front engine mountings are several inches behind the rear wheels trailing edge, the seat base is 7 1/2" below the top of the chassis and no heavy items sit high up in the car, but, to achieve this they had to move the springs outward to make room for the crew. I also expect that the longer wheel base provided increased directional stability for the straight line of the banking at Brooklands, which married to the improved cornering forces imbued by the lower G of G for the inner field bends must have made the weight issues of less concern. I will contribute a considerable proportion to the weight of the car, having my mass as low as possible will make a considerable contribution, however, I do rather wonder about the increased loads on tyres leading to other issues!
The chassis section housing the rear springs do not do very much, they locate the spring clamp onto a plate and provide some seat support and brake cable routing. They will confer some local strengthening between the rear cross members. I have not used chassis sections, these items where folded, as was the case for the front chassis extensions.
I am aware of the risks of damaging the car, especially the tail, suspecting that a key risk area will be in the paddock and assembly areas.
Regards,
Mark.
(28-05-2018, 10:29 AM)Tony Betts Wrote: Looking really nice mark,
How did the big bulg on the drivers side come out?
A bit worried you might be building it up in the kitchen though.
Tony.
Hello Tony,
The bulge is as you last saw it, because it is not on the critical path it keeps getting left on the shelf, but, I have good intentions to finish any day now!
It is not in my Kitchen, not yet anyway, but, the French windows in my garage are the result of a choice to make it as pleasant an environment as possible, with lots of natural light and you can see the cars from my house.
Regards, Mark.
RE: Anatomy of Slippery Anne - Timothy P - 30-05-2018
I think I've used the words before, but your updates are always truly awe inspiring.
Thank you once again for sharing your progress, it is always fascinating.