Lotus E21 construction report part 9

Chassis finishing off

As reported in the last post, the chassis was in the paint process over the last few days. This car is the first one, where I created a really planed paint process. There were four steps:

  • 1st Step, paint preparation: Sanding every single surface of the car and especially cutting edges up to 1500 sand paper. After sanding, all sponsor labels were added as quick as possible to avoid damage or whitening. Quick clean of the main surfaces to get rid of big dust particles or similar contamination.
  • 2nd Step, prime coat: Tape all surfaces that need no highly polished surfaces (means monocoque inside, chassis sides behind side pod intake). Applying first coat of clear lacquer immediately after finishing with the first step. Applying 9 layers at all. Waiting at least half an hour between applying next layer.
  • 3rd Step, main coat: Add all missing non highly polished surfaces to the chassis (monocoque underside, front bulkhead, radiator ducts,…). Applying additional five coats of clear lacquer and drying it on a radiator. Waiting at least one hour between every single coat.
  • 4th Step, subsequent improvement: Inspect painted surfaces and apply another few spray dots to faces where no polished finish yet.

And the result of this process is astonishing! I never got such a nice surface quality and highly polished finish of the car. I will apply this process from now on at every car with probably a few improvements.

After the paint process it’s obviousely very critical to work on the car (avoiding surface containment). When I’m working on a specific area on the car, I have to cover the surrounding surfaces with some tape stripes. What I also detected during working on the car shortly before the paint process is, that the monocoque is fucking extremely stiff and rigid. I was hardly struggling to get the holes for mirror assembly and nose pins done. With a hammer and a scriber and nail I was working for several minutes to get this four holes onto the car. That means, that the implementation of my thoughts about how to get the chassis stiffer and not significantely heavier has taken full effect. I guess I was never so satisfied with a chassis as I am at the mo. Although there could be some minor improvements, but that can wait till the next car.

During the paint process, which contains a lot of waiting (which I partly bridged by drinking beer), I also started the manufacturing of the engine. The manufacturing of the engine block is one of the most annoying parts of the car. Machined metal parts, the most time consuming work in paper modelling. It’s a pain in the ass!


The chassis shortly before the paint process. All surfaces were treated to 1500 sand paper. Few sponsor logos and rear mirrors missing.


Within the paint process. Immediately after applying the lacquer, the car always looks perfect, but after drying you’re back in reality… It takes an awful lot amount of time to get a proper paint job done.


Prime coat: Nine layers of lacquer results in this milky look. But the surface is already wonderfull. All edges are beatuifully blended and smooth. After this, I had to wait for 24 hrs plus, to rework the car before applying the final main coat.


One part of the car rework was f.e. the fit of the rad ducts. As you can see, I taped off the surrounding surfaces to avoid contamination of the nice surface.


This is also the first car, where I really planed a fastening system for the whole bodywork panels. And I hope it will work. It’s kind of the same system as it’s on real F1 cars. Here you can see the fit of one fastener…


“Machining” the holes for the nose pins. I would say, in combination of glue and my treatment of the paper, this components are much harder than some plastics or woods…


First pic after finishing the 3rd paint step.


Finished chassis with (non painted) heatshield.


Current state of the car with half finished radiators and in production progress being engine block.


Front bulkhead.

Here are just some pictures to show you the incredible surface finish of the car:


The Kimi logo is the only one I did by hand. There was no suitable Kimi logo available on the net.


I think in this pic, you can clearly see the really incredible finish of the chassis. Hopefully all parts of the car will get like this.


Lotus! It would be interessting to know, if I already caught Lotus’ attention with my work as it was at the RB7 and the Audi R18 TDI.


The thing I was most worried about were the side pods. Especially this extension (with the burn on it) which are housing the side impact structures. But with my now developed paint process, it got awsome…

Best wishes,



About paulsf1

My name is Paul Bischof. I’m a student in mechanical engineering at the Technical University of Graz in Austria, expected finishing in February 2016. Since I was eight years old, I am building model planes out of paperboard. Since 2004 I scratch (that means building without an assembling set) Formula 1 and sportscars in 1:10th scale. The average time I need for such a car is around 400 to 700 hours within 4 to 8 months. One car has around 3500 up to 5000 single components. On this blog, you can take a look on my work and later, after my studies, hopefully you can see me in Formula 1.

2 responses to “Lotus E21 construction report part 9”

  1. AkiyamaWataru says :

    Extremely nice work! Can you give some insight how you baked your carbon…. i mean your paper/cardboard?


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