Lotus E21 construction report part 18

End of “creative break”

Finishing rear wing and start of of internal duct design. Furthermore – finishing my Bachelor degree.

As my Facebook followers might have noticed, I had something like a creative break on building my Lotus. Main reason for this is to find on uni. As I was finishing my BSc degree in Mechanical Engineering and starting my Master studies, there was a lot of stuff to execute. I guess, now in the summer month, there should be much more progress on the car than during the past few month.

Two days ago, I restarted working on my E21. The last few bits I did on the car was assembling, painting and fitting the rear wing to the car.

After removing the existing side pod cooling ducts due to non-compatible size of themselves (a design error), I started to design new one with all the given circumstances. The left cooling duct houses the water and gearbox-oil radiator, the left one engine-oil and ERS radiator. I’m still not completely sure, where the hydraulics cooler sits. Probably at the top of the monocoque below the airbox. As you will see in the pictures below, it’s a tough challenge to achieve the extremely tight packaging, especially in the area around the exhaust system and the radiators.

The airbox is a bit more complex than the previous airboxes I’ve built so far, but the design process didn’t showed any big problems.

Next things on the to-do list are finishing these ducts, than design and build all the electronics sitting in the side pods (ECU, PCU,…) and the PDRS ductings. Now let’s take a look onto the car.

Rear Wing

Assembled rear wing, DRS and central stay are missing. To keep in mind, the fully assembled rear wing consists of 120 parts – actually not a lot if you compare it with the 100+ parts of a steering wheel. 😀

Car rear view

Car rear view with fitted rear wing.  The wing is mounted via a stay on each endplate onto the top floor surface and a central support, connected to the rear crash structure. Notice the nice monkey wing, which will support the PDRS second pipe later on.

Rear Wing fixing point floor

That’s the rh rear wing end plate fixing point. These points are mainly to balance the wing. Most of the load goes thru the central stay which you can see on the next pic.

Rear Wing central fixing point

The rear wing central fixing point is mounted on the rear crash (which is naturally very stiff). With the ban of the beam wings in 2014 (which is a bit of a weird regulation change in my opinion), the central support is replaced by a big stay, connecting the top of the gearbox with the main rw flap (you can see this an all current cars).

Rear Wing DRS

The rear wing flaps with DRS. Also notice the slats in the RWEP. That was a tough challenge to get them reasonably good looking. The wing is a bit dusty – I should clean the car.

Rear Wing strakes

RWEP with its remarkable mini strakes.

Cooling duct left

Lh side cooling duct for the water and gearbox-oil radiator. You can see how challenging it is to achieve such a tight packaging. The exhaust system lies just above the radiators.

Cooling duct right

Lh side cooling duct for the engine-oil and ERS radiators. The ERS radiator will be mounted on the lower end of the duct where you can see the small slot.


The airbox with its jig.


Airbox fitted to the car.

Car top view

Car top view


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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 18”

  1. Guy Fortabat says :

    You did a very nice job on this car !!!
    My grandson (5 years old) asked me to build a F1 car, and looking on google images, he immediatly pointed to the E21 in the middle of all cars.
    I have a question: I have turned around in so many sites, that I have all external details for this car.
    But for the inside, there is no way to have satisfactory pictures.
    May I have some help from you to know where I have to look at ?
    Thanks a lot for helping !
    Guy from Paris


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