CANAMSA - T70 spyder inspired scratchbuild in SA

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CANAMSA - T70 spyder inspired scratchbuild in SA

Postby FredWB » Sun Jan 13, 2008 11:49 am

Hi All

I am a 44 year old mechanical engineer and motor sport enthusiast in Port Elizabeth, South Africa and have been lurking on this site for a while, and have been encouraged by Johan to post some details of my project.

I am building up a self designed space frame two seater mid engine sports car from scratch. I will use it on the road for fun and possibly do some track racing, in our "classic" class out here. When I started my project (in early 2004) I did not have a particular body in mind, I just wanted to build a car. But you see some home built unique body cars that just don't look great, and I didn't want to do all this work (building a car) and not have it look good. So I decided to follow a car that is accepted as looking good to everyone, that is, the Lola T70 spyder.

So far I have a prototype chassis complete, all the running gear figured out, and had the engine running in the proto chassis. I posted some pictures below of what the (very rough) mock up chassis looked like, with several of the tube joints not properly made, some tube sizes still to be decided, and the joints only partially welded.

I am using a Rover engine and Audi AAZ 016 trans. I designed and made the exhausts, adaptor/mounting plate and flywheel, amongst other bits. The riveted on 1.6 mm ally side boxes more than doubled the chassis torsional rigidity from 2700 ftlb/Deg to 5700 ftlb/Deg. The chassis mass is 96 kg.

Once I have a body, I am going to build the car up to running the engine condition in the proto frame, then finally build the real frame and swap all the bits over. I do intend to simplify the front and rear of the frame once I have finalized the suspension. I will do this once I have the WOW (width over wheels) dimension correct, and for that I need the body. I am determined to get the body mounted and all the bits like radiator etc mounted as well as the suspension sorted out so I can design and make all the required brackets, front and rear subframes etc before making the REAL chassis. I also have had some ideas in the meantime on how to improve and simplify the chassis, so will have an opportunity to do this then.

I am doing it this way as I really don't want to rework or compromise anything in order to get something to fit once I (finally) build up the car for real. I want to have everything in an optimum place to avoid having any of those "You know, if I'd just put that chassis rail (or whatever) 30 mm further out/in/along, I could have got this part in easier, and that part would have looked/worked better" moments once I stand back and look at the almost complete car.

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and this is me. The cheesy grin is because I had just started the motor for the first time.


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FredWB
 
Posts: 33
Joined: Sun Jan 13, 2008 11:46 am

Postby FredWB » Sun Jan 13, 2008 11:59 am

With regard to body work, I am currently busy with construction of a body pattern, in order to make moulds and bodywork.

I started by purchasing a 1:18 scale model of a Lola T70 Spyder and made up a 3 axis measuring jig in order to measure it, on a 5 mm x 5 mm grid. A friend of mine then used this data and some reference photo's to draw the body surface in Inventor. All the CAD work (which took a hell of a lot of hours) was done as a favor.

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FredWB
 
Posts: 33
Joined: Sun Jan 13, 2008 11:46 am

Postby FredWB » Sun Jan 13, 2008 12:02 pm

That data was then used to produce many flat body sections and some longitudinal stringers on a CNC router from 8 mm plywood sheet. The parts were drawn with slots so that they would clip together and self align.

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FredWB
 
Posts: 33
Joined: Sun Jan 13, 2008 11:46 am

Postby FredWB » Sun Jan 13, 2008 12:09 pm

The ribs and stringers were assembled on a base board, with the aid of longitudinal "skewers" that were planned straight and to size to fit holes cut into stations

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FredWB
 
Posts: 33
Joined: Sun Jan 13, 2008 11:46 am

Postby FredWB » Sun Jan 13, 2008 12:14 pm

In order to form the surface polyurethane foam blocks were cut, glued into the spaces and sanded to shape.

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FredWB
 
Posts: 33
Joined: Sun Jan 13, 2008 11:46 am

Postby FredWB » Sun Jan 13, 2008 12:17 pm

The rear air intake ducts "hip nostrils" have been one of the worst bits to get right, and one I have been working on a bit, leaving to do something else, and then going back to. We didn't get this area right in our computer model, so I had to go back to old fashioned first principles, shaping by eye from the model and photo references, and using wood and cardboard templates to get the left and right sides to match.

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FredWB
 
Posts: 33
Joined: Sun Jan 13, 2008 11:46 am

Postby FredWB » Sun Jan 13, 2008 12:20 pm

[By this stage, I started to run into a problem that some people had raised, in that the original model I scaled from may not be "correct".
Also I have still not yet personally seen a real (or replica) T70 spyder in the flesh and trying to get the proportions and some of the details more or less right from photographs has been driving me crazy, not helped by the fact that the model I started with, the various original mk1, mk 2 1960's cars in period (and now), the Heritage cars, the GD / RCR narrow shell replicas etc are all slightly different in certain areas to each other.

So what I have decided to do is take the bits that I liked best from each of these cars and will hopefully end up with something that I at least think looks good. For example, I made the nose radiator duct wide enough to suit the biggest radiator Summit list and kept the duct sides parallel as on the coupes, because I prefer the look over the tapered sides. Part of me wants some things on the body that are obviously not "correct" as proof of my intent to not attempt a perfect replica.

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FredWB
 
Posts: 33
Joined: Sun Jan 13, 2008 11:46 am

Postby FredWB » Sun Jan 13, 2008 12:22 pm

The biggest problem stemming from the accuracy of the scale models was the length of the tail of the body aft of the rear wheel arch. It's most apparent if you look backwards along in line with the top of the rear tyre. Once I saw it I couldn't to imagine how I missed it, and I have been looking at T70 pictures for literally years. I had built a perfect replica of the model, but it was just wrong! I decidede to shorten my plug behind the rear arch by about 90 mm

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FredWB
 
Posts: 33
Joined: Sun Jan 13, 2008 11:46 am

Postby FredWB » Sun Jan 13, 2008 12:23 pm

Before shortening

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After shortening

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FredWB
 
Posts: 33
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Postby FredWB » Sun Jan 13, 2008 12:27 pm

The rear transom panel turned into a real mission

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FredWB
 
Posts: 33
Joined: Sun Jan 13, 2008 11:46 am

Postby FredWB » Sun Jan 13, 2008 12:32 pm

I decided I wanted the want the wheel arch lips to look like this car.

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FredWB
 
Posts: 33
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Postby FredWB » Sun Jan 13, 2008 12:33 pm

WRT the screen, I have mocked up a windscreen template in hardboard in order to establish the angle of the windscreen recess.
I am hoping to use a flat piece of Lexan cut to shape with a single plane curve. I don't like the look of the original style screen, and the scuttle on my shape is much higher than the original originals. I say that as the heritage cars seem to be higher there also.

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FredWB
 
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Postby FredWB » Sun Jan 13, 2008 12:34 pm

Other reworks I had to do were to the contours along the top of the doors, into the top of the front wheel arches


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FredWB
 
Posts: 33
Joined: Sun Jan 13, 2008 11:46 am

Postby FredWB » Sun Jan 13, 2008 12:38 pm

Where I have deviated from the original routed stations, I have to make templates to check symmetry of the profile on the LH and RH sides. The filler you see is interior grade plaster filler (brand name "polyfiller") over the foam in areas where I am reworking and cutting into the foam between ribs, in order to see the finished shape ,


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FredWB
 
Posts: 33
Joined: Sun Jan 13, 2008 11:46 am

Postby FredWB » Sun Jan 13, 2008 12:39 pm

In order to keep the body as symmetrical and "square" as possible, I check everything back to a horizontal reference plane I have across the back of the cockpit. Have to be careful you don't loose the centerline on the pattern!


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FredWB
 
Posts: 33
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