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Lotus E21 construction report part 23

Cockpit electronics, suspension stuff, exhaust system, brake discs, internal aero and more.

This post sumarizes the work I’ve done over the past two month. A lot of small stuff like fuel fillers or electronic boxes, but also massive projects like front-and rear suspension and exhaust system.

The completion of the car is optimistically aimed to early spring, maybe March. Unfortunately it is too cold now, to do the paint jobs on the balcony. So the flat is a bit smelly from time to time. 😀

The to-do-list is pretty short now:

  • Belts
  • Cockpit padding
  • Brake calipers and cooling ducts
  • Wheels, wheel hubs, wheel nuts
  • PDRS
  • Internal aero
  • Engine cover
  • Rear light

Next to come are the brakes.


Exhaust system is done. The packaging is really thight and it will get interessting to wrap the engine cover around it.


Gearbox and clutch control unit on top of the gearbox housing. BTW. Lotus/Renault is one of the very few teams, which is still not using a carbon gearcase.


Cockpit internals are also done.


Fuel filler – top (red) one is the fuel valve, the bottom (red) one the venting.


Internal aero surface – this secures a clear and low drag tunnel for the cooling air.


Rear suspension


Front suspension – wishbone structure


Front suspension


Brake discs – each consisting from 19 parts


Lotus E21 construction report part 22

Brake fluid reservoirs, exhaust pipes, fire extinguisher, radiator pipes, beer and more…

Nice progress over the last days. There’s not a lot missing any more. Main sites are front suspension, brakes, brake ducts, wheels and engine cover.

When I come to the end of a car build, I usually create a to do list with all the stuff on which is left. On this list I rate all elements with

+ which means, it’s an easy, quick and nice, simple to build element

~ which means, it’s a pretty simple element, but takes it’s time and is not that nice to manufacture

– which means, it takes a lot of time to build the element

Front suspension, cockpit padding and engine cover are the last three minus elements (maybe also the rims).

The components and assemblies, I produced during the last few days are stuff like exhaust end pipes (with their helmholtz resonater – more on that in picture caption below), fire extinguisher, brake bias lever, dashboard, roll sensor, brake fluid reservoirs, pitot tube and some electronic stuff at the front end of the chassis.

Beside all this, I created a rim instruction. So the rim design is already done.

Unfortunately I lost the drive shafts during the summer… 😦 So light delay at the rear suspension build.

At the moment, the car is at about 4000 parts.


Front view of the steering wheel – it consists of 107 single parts and has a diameter of 27mm. For comparison, the RB7’s wheel has 73 parts and the R18TDI’s wheel (much bigger) has 109 parts.


Back view of the steering wheel with clutch and gear shift paddles. At the best sake, I can’t remember any more, what the top lever is. It seems, I got a little rusty… With the ruler beside, you can actually imagine the size of all these tiny elements.


A view into the chassis with removed seat and steering wheel. At the bottom, you can see the fire extinguisher, right handed the fire extinguisher switch as well as the ignition switch are mounted. At the left hand side, the brake bias lever is mounted.


Just the seat straps are missing – but it’s actually hard to find suitable straps with the right colours and fabric.


That are the raw exhaust pipes. They consist of a steel wire inside and a thick paper cover (many cylindrical layers). Before painting, the whole structure is covered with a thin layer of glue and sanded down to get a clean surface. The pipe which is sticked on the actual pipe is the helmholtz resonator. It simply provides a steady exhaust gas flow to get a nice blown floor. For an exact description of the effect, just google. It’s basically pretty simple.


The right hand exhaust pipe during the painting process. The left and the right pipes are a little different due to the different space conditions in the side pods (oil radiator right handed, water radiator left handed). The paint jig (beer crate and a steel wire) is a bit unorthodox, but it’s simple and it works. 🙂


The right hand exhaust pipe in the side pod. It’s not fixed yet, as the lacquer is still curing. But somehow in this position it will be later on. The packaging of these cars was already quite tight, but not really comparable to the current generation of hybridcars.


The left hand side pod without its exhaust pipe. But the feeding lines for the water radiator are fitted.


Something is going on at the front of the chassis. It’s fully packed with brake fluid reservoirs, some gauge instruments and some electronics. Clearly visible, the pitot tube (air speed) at the top and the roll sensor at the bottom.


That’s the roll sensor, nicely shaped.


To get an imagination on the size of all these  elements… Note also, there’s a 1 € Cent coin (diameter 16.25mm) lying on the chassis.


To do list


Rim instruction – all these parts are needed to produce a rim.

PaulsF1 at Red Bull Racing

Hi all,

as you may know, in 2012 Rob Marshall, Chief Designer of Red Bull Technology, respectively Red Bull Racing, offered me a student placement job at the Formula 1 team. In August 2013, I started this challenge as a composite design engineer. Designing parts all over the car (RB10), I gained a very lot of experience in race car design and the work in a F1 team. In October 2014, I returned to Uni (Graz University of Technology), to finish my master studies in mechanical engineering. Here is a short video clip, produced by ServusTV which was part of a documentation about Austrian engineers in motorsports.



2014 in review

The stats helper monkeys prepared a 2014 annual report for my blog.

A special year ends for me. The obvious highlight was working at Red Bull Technology, a lifetime dream got true! This experience ended up in our special vid which was produced by Siemens in cooperation with RBT. Click here to watch. In meantime I am back on uni finishing my studies in MechEng before returning to Formula 1.

In terms of building my paper cars, it was a bit more quiet than the years before. There was some progress on my Lotus, however I’m working now over 16 month on this car. The famous RB7 took me just 12 month. But there’s some light at the end of the tunnel: I expect to finish the E21 in summer.

Last but not least, my FB page has now more followers than my native village has inhabitants (that’s actually not that difficult, as we have just a bit less than 1300 inhabitants 😀 ).

Anyway, I want to greet all of my fans with this and wish you a happy new year and you’ll read from me in 2015.

Cheers, Paul!


Here’s an excerpt:

The Louvre Museum has 8.5 million visitors per year. This blog was viewed about 180,000 times in 2014. If it were an exhibit at the Louvre Museum, it would take about 8 days for that many people to see it.

Click here to see the complete report.

Paper Dreams – a Story by David Betteridge

Hi Chaps!

A bit belated, but finally this great video, which resulted from the great work of Video Director David Betteridge in cooperation with Siemens and Red Bull Racing, shows my rise from a simple model builder to a proper Formula 1 car designer.

I just want to say a huge thank you to all the people who supported me on my way into Formula 1. Enjoy!

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,


Lotus E21 construction report part 8

Chassis ready for Paint Shop

Just a short, but reasonable update. Chassis is now finished for 1st stage painting! During paint process I’ll start off with the engine.


Last minutes before the chassis goes to the paint shop!

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